Comprehensive Microbial List Flashcards
1
Q
Yellow Fever
A
- mosquito vector (South America + Africa) flavivirus -coagulative necrosis of hepatocytes
- Presence of apoptotic (Councilman) bodies in liver biopsies.
- abrupt onset of fever, chills, headache, myalgias, nausea, and vomiting.
- 3-5 days, hepatic failure with jaundice, clotting factor deficiencies, and diffuse hemorrhages.
- “Black vomit” is classic feature of severe cases.
- High mortality rate
1
Q
Gonnorrhea (Neisseria Gonorrhoeae)
A
- P2P: sexually transmitted + perinatal transmission
- aerobic, bean-shaped, gram(-) diplococcus
- pili with IgA protease: attach to transitional epithelium of columnar/transitional epithelium of urogenital tract
- acute inflammtory response-abscecess
- Men: purulent urethral discharge, dysuria, orchitis, epididymitis (may cause infertility)
- Women: 50% asymptomatic, endocervicitis, vaginal discharge/bleeding, urethritis with dysuria, chronic salpingitis, pelvic inflammatory disease (infertility if tubes swell/blocked with pus), endometritis, Fitz-Hugh-Curtis Syndrome (healing fibrous attachement liver–parietal peritoneum)
1
Q
Clonorchiasis / Liver fluke (Clonorchis sinensis)
A
- Asia, Vietnam, Korea
- spread by ingesting inadequately cooked freshwater fish
- flat and transparent adult
- lethal due to complications: biliary obstruction, bacterial cholangitis, pancreatitis, cholangiocarcinoma
2
Q
Human Papillomavirus
A
- person to person contact (STD) -genital warts + cervical cancer (common manifestations)
- depressed cell-mediated immunity with spread of HPV lesions
- koilocytosis: large squamous cells with shrunken nuclei in large cytoplasmic vacuoles.
3
Q
Gerstmann-Straussler-Scheinker Syndrome
A
- rare transmissable spongiform encepalopathy
- dementia common feature
- some rare sporadic cases, usually familial
3
Q
Paracoccidioidomycosis (South American/Brazilian Blastomycosis)
A
- similar to coccidiodomycosis + blastomycosis
- chronic granulomatous infection starting with lung involvement–dissemination in immunocompromised to skin, oropharynx, adrenals, and macrophages of lymphatic system.
- central + south america
- usually acute, self-limited and mild disease
4
Q
Rubella (German Measels)
A
Epidemiology: Spreads by respiratory route. World wide locus. Not highly contagious (only 10-15% unvaccinated women remain susceptible into reproductive years). live attenuated viral vaccine prevents rubella.
Pathology: Infects repiratory epithelium and spreads to bloodstream and lymphatics. Rash results from immunologic response to virus and resolves in 3 days. Fetal infection occurs through placenta during viremic phase of maternal illness. Fetus remains persistently infected. Heart, brain, eyes most frequently affected in fetus.
Clinical Features: Febrile illness, rhinorrhea, conjunctivitis, postauricular lymphadenopathy. 30% infections asymptomatic. Fetus: pulmonary valvular stenosis, pulmonary artery hypoplasia, ventricular septal defects, and patent ductus arteriosus. Cataracts, glaucoma, and retinal defects. Microcephally and mental retardation
4
Q
Shigellosis (Shigella dysenteriae)
A
- aerobic, gram(-) rods
- SELF-LIMITED necrotizing infection -spread oral-fecal route (fecally contaminated food/water or surfaces)–areas of poor sanitation
- self-limiting disease (3-8 days) with watery diarrhea
- 300,000 annual cases in US diarrhea/dysenteric stools, abdominal pain, tenesmus, fecal urgency
- Produces Shiga exotoxin: inhibits protein synthesis and inhibits fluid absorption in colon)–affects distal colon and sometimes distal ileum–dysentery
- infected mucosa is edematous, inflamed, eroded with presence of pseudomembrane composed of neutrophils, fibrin, and necrotic epithelium (healing complete in 10-14 days)
5
Q
Meliodosis (Burkholderia pseudomallei)
A
- a pulmonary infection that can cause cavitary pneumonia with high fever, splenomegaly, hepatomegaly, septicemia, and shock–SEVERE
- flourishes in wet environments (Vietnam) and enters skin through lesions, burns, or wounds as well as aerosolized droplets
- incubation time months to years
- liver, spleen abscesses in 25% of infected
6
Q
Mucormycosis (Zygomycosis)
A
- Environmental fungi, cause severe necrotizing, invasive infections that begin in sinuses and lungs (spores are inhaled)
- Rhinocerebral: creates a black crust with friable/hemorrhagic underlying tissue - spreads to vessels and brain. Tx = surgery, amphotericin B, may be fatal
- Pulmonary: Usually fatal, looks like aspergillosis (sepsis and infarction)
- Subcutaneous zygomycosis: In the tropics, hard inflamm. mass on shoulder, trunk, buttock, thigh
7
Q
Mycetoma
A
8
Q
Sporotrichosis
A
- Rose Gardner’s disease
- chronic granulomatous skin infection with suppurative center
8
Q
African Trypanosomiasis (Trypanosoma brucei rhodesiense)
A
- Tetse fly
- Acute febrile progresses to life threatening meningoencephalitis-3 to 6 months
- Humans only reservoir of T. brucei
- evade immune system by altering glycoprotein antigen coat–genetically determined pattern (not mutation)
- Disruption of sleep, neurological problems.
- Fatal if untreated
8
Q
Paragonimiasis / Lung fluke (Paragonimus westermani)
A
- spread through ingestion of uncooked crab
- Korea, Philippines, Taiwan, China
- peripheral eosinophilia-distinguishing factor against TB + eggs in sputum or stools
- frequently misdiagnoses as tuberculosis
9
Q
Candida (albicans)
A
- Usually superficial (deep infections uncommon and life threatening)
- Endogenous flora, most common precipitating factor = antibiotic use. Yeast converts to invasive hyphae or pseudohyphae form.
- Limited to mucocutaneous sites:
- Thrush = oral cavity, fuzzy white coat on tongue (maceration predisposes)
- Vulvovaginitis = thick white discharge, itchy (antibiotics, preg., diabetes, steroids)
- Sepsis and disseminated candidiasis = usually deadly (catheter, IV, dialysis)
- Endocarditis = large vegetations (IV drug use)
- Other surfaces include esophagitis, paronychia (nailbeds), diaper rash and intertrigo (opposed skin surfaces)
10
Q
Pseudomonas aeruginosa
A
- Gram-negative, aerobic, coccobacillus bacterium
- highly antibiotic-resistant
- nosocomial pneumonia, wound infections, UTI, and sepsis
- proteoglycan coat protects against ciliary action, complement, and phagocytes
- elastase, alkaline protease, cytotoxin (exotoxin A)– ADP-ribosylate/inhibit EF-2 (like diptheria toxin) facilitate tissue invasion
- ECTHYMA GANGRENOSUM: disseminated infections causes these skin lesions
- AGRESSIVE: rapid sepsis progression (exotoxin + endotoxin production)–hemorrhagic necrosis + thrombosis
10
Q
Tuberculosis (Mycobacterium tuberculosis hominis, M. bovis)
A
- Spreads by aerosols from person to person, enters into the lungs
- Forms GHON COMPLEX lesions in lungs (area of infection + lymph nodes) - contains caseous granuloma (necrotizing center) / hilar lymphadenopathy,
- Most cases of primary TB are asymptomatic. In progressive cases (kids, immunocompromised, homeless) non specific symptoms (fever, night sweats, weight loss, fatigue).
- Secondary TB (reactivation or reinfection) - T-cells are already familiar with antigen and cause necrosis and cavities in lungs. Same as primary symptoms + hemoptysis. Disease may disseminate (miliary) and become fatal.
- Todays treatment - long term antibiotics.
11
Q
Lyme disease (Borrelia burgdorferi)
A
- Zoonotic spirochete, Transmitted by ticks, reservoir = mice, deer.
- Stage 1: erythema chronicum migrans (characteristic annular red lesions), fever, malaise
- Stage 2: muscle, heart, and nerve problems, including meningitis and facial nerve palsy
- Stage 3: more joint, skin, and nerve problems - mimics rheumatoid arthritis
- Late manifestations (years later): acrodermatits chronica atrophicans, patchy atrophy and sclerosis of skin
- Diagnosis usually established using antibody titers
11
Q
Rocky Mountain Spotted Fever
A
- Tick-borne, caused by Rickettsia rickettsii , Gram (-) coccobaccilus.
- obligate intracellular pathogen
- Serious, life-threatening illness.
- Early presentation is non-specific, febrile.
- 2-5 days after fever
- Maculopapular or petechial rash spreading from limbs toward trunk.: from infection of vascular smooth muscle and endothelium of large and small vessels
13
Q
Ascariasis (Ascaris lumbricoides)
A
- ingestion of food contaminated with eggs
- most common helminthic infection in humans
- usually ASYMPTOMATIC
- penetrate small intestine and travel to lungs
- can cause obstruction of pancreatic or biliary ducts-pancreatitis, suppurative cholangitis, and liver abscesses.
- Ascaris pneumonia (rare): larvae fill alveolar airspaces
14
Q
West Nile Virus (Flaviviridae)
A
- CSF with leukocytosis,CSF is clear with mild pleocytosis and elevated protein in CNS infection.
- meningoencephalitis (Medulla).
- Fever, Rash, lymphadenopathy, and polyarthropathy.
- not very infectious, but severe disease has moderate mortality
- most dangeous in elderly and immunocompromised
14
Q
Streptococcus Pyogenes (Group A)
A
-normal bacterial flora of skin and oropharynx
-pharyngitis (strep throat), cellulitis, myositis, pneumonia, puerperal sepsis.
-exotoxins plus cytotoxins.
-Rheumatic fever and glomerulonephritis–complications -
Scarlet Fever (red rash-erythrogenic toxin)
-erysipelas (erythematous swelling of skin)
-Impetigo (intraepidermal infection): spread direct contact in children
15
Q
Tetanus (Clostridium Tetani)
A
- obligate anaerobe, gram(+), spore forming
- causes ascending paralysis
- produces potent neurotoxin tetanospasmin (blocks release of inhibitory neuropeptides) that causes lock jaw, and respiratory spasm–death
- invades through contamination of open wounds
16
Q
Pinworm Infection (Enterobius vermicularis)
A
-
17
Q
Tularemia (Francisella tularensis)
A
- reservoir in rabbits and rodents infection from contact; vector is ticks, deerflies, and mosquitoes.
- metastatic infection–survives within macrophages (granulomatous reaction)
- Acute febrile disease, lymphatic distribution.
- Distribute to major organs via lymph => enlarge, hard nodes => granulomas (necrotizing, described as ‘palisading’)
- Ulceroglandular: pustular lesions (necrosis) with lymphadenopathy and acute febrile illness–significant mortality if untreated
- Occuloglandular = Spread from eye to parotid gland
18
Q
Lymphatic Filariasis/”Elephantiasis” (Wuchereria bancrofti)
A
- transmitted via mosquito bites
- inflammatory parasitic infection of lymphatic vessels: lymphangitis and sometimes lymphatic obstruction
- edema with thickening of the skin and underlying tissue-elephantiasis
- Often unilateral, involving scrotum/leg
- Occult filariasis (anti-filarial antibodies) produces tropical pulmonary eosinophilia–can lead to fatal pneumonia.
19
Q
Epstein-Barr Virus
A
- infectious mononucleosis: fever, malaise, pharyngitis, splenomegaly
- lymphadenopathy–spleen and lymph nodes (cervical)
- atypical lymphocytes
- heterophilic antibody–distinguishing lab test
20
Q
Ebola Virus (Filoviridae)
A
- Epidemiology: First emerged in Africa, Zaire and Sudan in 1976. Outbreaks caused by Ebola Zaire and Sudan strains primarily. Outbreaks occured in Gabon, Republic of Congo, and Uganda. Fatality rate 53 to 89%. January 2008–Ebola Bundibugyo strain emerged in Uganda. Fruit bats are reservoir for virus. Virus can be spread by bodily secretions, blood, and used needles.
- Pathology: widespread destructive tissue lesions–most damage of all viral hemorrhagic fever agents. Replicates in endothelial cells, mononuclear phagocytes, and hepatocytes. Necrosis is most severe in liver, kidneys, gonads, spleen, and lymph nodes. Hepatocellular necrosis + Kupffer cell hyperplasia, Councilman bodies, and microsteatosis seen in liver biopsies. Lungs hemorrhagic and petechial hemorrhages seen in skin, mucous membranes, and internal organs. Injury to microvasculature–increase vascular permeability leads to shock.
- Clinical Features: incubation time is 2 to 21 days. Initial symptoms headache, weakness, and fever, followed by diarrhea, nausea, and vomiting. Severe disease characterized by overt hemorrhage including bleeding from injection sites, petechia, GI bleeding, and gingival hemorrhage.
20
Q
Cholera (Vibrio cholerae)
A
- aerobic, curved, gram(-) rod
- spread from ingesting contaminated food/water; shellfish are natural reservoir–sporadic outbreaks
- epidemics in areas where human feces pollute water supply -cholera exotoxin: binds GM1 ganglioside in enterocyte cell membrane to enter cell and activated adenylyl cylase- increase cAMP and increase Na+/H20 secretion into intestinal lumen. -severe watery diarrhea with flecked mucus (rice water stools)–leads to fluid and electrolyte loss that leads to shock
- 50% mortality rate in untreated patients (lacking electrolyte and oral rehydration therapy +antibiotis)
- vaccine available (50% effectiveness)
20
Q
Syphilis (Treponema pallidum)
A
- Gram(-), highly motile. -granulomatous–taken up by macrophages
- Pyogenic STD with 3 characteristic stages
- Primary: Chancre (firm, painless) with luetic vasculitis, occasionally multiple lesions in immunecompromised.
- Secondary: (involves systemic spread) Maculopapular rash on palms and soles of the feet, follicular and numular syphilids, condylomata lata (white plaques on perineum region), obliterative endarteritis.
- Latent stage: Asymptomatic
- Tertiary (3-15 yrs after infection): Gumma: soft, tumor-like balls of inflammation which may vary considerably in size. NeuroSyphilis - meningitis, seizure, dementia + tabes doralis (peripheral nerve demyelination) Cardiovascular syphilis- aortitis => aneurism.
- Congenital syphilis can cause snuffles, saddle nose, saber shins, and Hutchinson teeth in newborn
21
Q
Yaws (Treponema pallidum pertenue)
A
- Found in tropics, skin-to-skin transmission
- Pyogenic: neutrophilic Raspberrry-like papilloma lesion.
- Diffuse skin lesions, ones on the sole of feet can cause “Crab Yaw” walking
- After a latent period, re-emerges as face and upper airway lesions
21
Q
Fascioliasis
A
- spread by eating contaminated vegetation (watercress) with cysts from sheep
- cysts liberate metacecariae that pass into peritoneal cavity–live in intrahepatic and extrahepatic bile ducts
- hepatic abscesses and granulomas
- induce hyperplasia of bile duct epithelium, portal and periductal fibrosis, and biliary obstruction
- Symptoms: eosinophilia, vomiting, acute gastric pain
- Fatal if untreated
- diagnosis: recovering eggs from stool or biliary tract
22
Q
Cystic hydatid disease / Echinococcosis (Echinococcus granulosus)
A
- endemic in sheep, goats, cattle, and sheep dogs
- humans contaminated by dogs: ingest tapeworm eggs spread by dog in human living spaces
- cestode has suckers and hooklets facilitating attachment
- larva penetrate gut wall, enter bloodstream, disseminate into deep organs
- form large (hydatid) cysts containing brood capsules and scolices
- cysts can compress intrahepatic bile ducts–obstructive jaundice
- Major complication: cyst rupture and seeing of adjacent tissues–proliferating cyst number and causing pain and fatal allergic reactions (anaphalactic shock)
24
Q
Psittacosis (Ornithosis) (Chlamydiae psittaci)
A
- Spread from Birds in tropics.
- Self-limited pneumonia,splenomegaly, rose-colored ‘Horders Spots
24
Q
Cryptosporidiosis (Cryptosporidium parvum)
A
- extracellular enteric infection
- diarrheal infection
- self-limiting, unless immunocompromised
- AIDS patients, etc, develop chronic infection with persistent chronic diarrhea that can lead to death
25
Q
Respiratory syncytial Virus (Paramyxoviridae)
A
- Epidemiology: Belongs to same family as influenza. Spreads rapidly from child to child in aerosols and secretions–daycare centers, hospitals and other areas with confined children.
- Pathology: Viral surface proteins interact with receptors on host respiratory epithelium-viral binding and fusion. Causes necrosis and sloughing off of bronchial, bronchiolar, and alveolar epithelium. Multinucleated syncytial cells seen.
- Clinical Features: Young children with RSV bronchiolitis or pneumonitis have wheezing, cough, and respiratory distress. Illness self-limited (1-2 weeks duration). older adults produces much more mild illness. 20-40% mortality among hospitalized children with congenital heart disease.
26
Q
Nocardia (Nocardiosis)
A
- respiration or cutaneous inoculation
- gram(+) aerobic filamentous
- May affect lungs, brain, skin or systemic dissemination
- Disease of immunocompromised.
- Pyogenic: Pulmonary abcesses w/ central necrosis.
- Fatal if untreated, long term antibiotics.
26
Q
Trichuriasis / Whipworm (Trichuris trichiura)
A
- ingested eggs in contaminated food, soil, drink
- Live in the Cecum or upper colon–children especially susceptible
- Invasion causes small erosions, focal active inflammation, loss of small amounts of blood
- Usually asymptomatic
- Heavy infestations causes cramping, abdominal pain, bloody diarrhea, weight loss and anemia
27
Q
Human Parvovirus B19
A
- Epidemiology: spreads person to person by respiratory route. Infection common and occurs in outbreaks, mostly among children.
- Pathology: gains entry to erythroid precursor cells via P erythrocyte antigen and produces certain cytopathic effects: enlarged nuclei with peripheral chromatin displacement and eosinophilic material nuclear inclusion bodies.
- Clinical Features: Mild exanthematous illness (rash) known as erythema infectiosum, accompanied by interruption of erythropoiesis (mostly asymptomatic). Potentially fatal anemia caused in hosts with chronic hemolytic anemia–transient aplastic crisis. Fetal infection leads to severe anemia, hydrops fetalis, and death in utero (10% of maternal infections).
27
Q
Yersinia pestis
A
- Gram-negative rod-shaped coccobacillus. It is a facultative anaerobe
- survive/proliferate inside macrophages (granulomatous + necrotizing)
- Produces plasminogen activator: hemorrhaging
- Bubonic plague: spread by fleas on rats-septic shock and bulbous enlargements of lymph nodes
- Septicemic plague: direct blood contamination (death quick-48 hours)
- Pneumonic plague: inhalation of airborne particles, endotoxic shock in 1-2 days after infection period which follows 2-5 day incubation -tetracyclin with streptomycin
28
Q
Clostridium Perfringens
A
- obligate anaerobe, spore forming, gram(+)
- bacterial benign, diarrheal food poisoning, necrotizing enteritis (enterotoxins-ulcerating ß-toxin), and gas gangrene
- GAS GANGRENE: myotoxin–alpha toxin (alpha lecithinase–phospholipase) that destroys cell membranes leading to severe hemolysis and muscle necrosis–SEVERE
30
Q
Dracunculiasis / Guinea worm (Dracunculus medinensis)
A
- infection of connective and subcutaneous tissues
- transmitted by drinking water contaminated with intermediate host, crustacean of genus Cyclops
- year incubation: symptoms: systemic allergic reaction, blisters that burst upon contact with water with female worm partially emerging
- dead worms provoke intense inflammatory response
31
Q
Coagulase negative Staphylococcus Epidermitis
A
- Gram(+) bacteria
- normal bacterial flora (skin, mucosal surfaces)
- not as serious as S. aureus infections
- low grade fever
- spread from contaminated medical and prosthetic devices. -nosocomial variants multidrug resistant. (use non-beta lactam antibiotics)
32
Q
Smallpox (Variola virus)
A
- Epidemiology: ancient disease. named after latin “varius” meaning “pimple/spot”. Common in Europe. Arrived in the new world by explorers and decimated native populations. Edward Jenner (1796) performed first vaccination by innoculating child with lymph from hand of milkmaid infected with cowpox. WHO began eradication campaign in 1967 leading to eradication in 1978 (Somalia last endemic cases). CDC and Russia still have virus stockpiled.
- Etiology: Spread between infected and susceptible hosts via droplets or aerosol of infected saliva. Virus highly stable and remains infective for long periods outside human host. Variola major (Asia and parts of Africa–prototypical) and Variola minor (Africa, South America, and Europe–minor systemic toxicity and lesions).
- Pathology: Skin vesicles of variola show reticular degeneration and areas of ballooning degeneration. Guarnieri bodies (eosinophilic, intracytoplasmic inclusion bodies) are seen, but not specific to smallpox (most poxviral infections). Vesicles also occur in palate, pharynx, trachea, and esophagus. Severe cases produce gastric and intestinal involvement, hepatitis, and interstitial nephritis.
- Clinical Features: Incubatin period: 12 days (7-17 days). Spreads to regional lymph nodes to produce viremia. Abrupt malaise, fever, vomiting, and headache manifest. Characteristic rash (face and forearms) follows in 2-3 days. After eruptions on lower extremities, rash spreads central during next week to trunk. Lesions: macules–>papules–>pustular vesicles–>scabs–>scars. Fatality rate is 30% in unvaccinated.
33
Q
Kuru
A
- prototypical prion disease
- neurodegenerative
- transmitted via ingestion (cannibalism of flesh)
35
Q
Noma / gangrenous stomatits / cancrum oris
A
- A disfiguring, smelly facial necrosis that destroys both soft tissue and bones of mouth and face
- Often targets malnourished kids in and immune compromised in the tropics
- Common bacteria: T. vincentii, B. fusiformis (fusospirochetal), Bacteroides, Corynebacterium
- Underlying bone may be revealed.
- Usually need antibiotics and reconstructive surgery
35
Q
Giardiasis (Giardia lamblia)
A
- aka “Beaver Fever” and “Backpacker’s Bug”
- usually self-limited, normally commensual protozoa
- Small Intestine, watery diarrhea.
- Symptoms of GI infection + bloating, excessive gas, and burping (often sulfurous)
- Malabsorption, structural and chemical changes to brush border.
- Watery diarrhea
- IgA deficiency?
36
Q
Pneumocystis jiroveci Pneumonia
A
- Inhaled, common in AIDS patients (probably latent endogenous infection), often fatal.
- Trophozoites (yeast-like) reproduce in alveolar type 1 cells and form cysts and rupture - alveoli fill with frothy eosinophillic material; diffuse lung inflitrate.
- Best seen with methenamine silver stains
38
Q
Histoplasmosis
A
- Histoplasma capsulatum.
- Primarily effects lung, typically SELF_LIMITED in HEALTHY.
- Intracellular, macrophages = > granulomatous, may resemble TB. => caseous necrosis + calcifications.
- Can dissemminate bone, spleen, liver, adrenal glands, mucocutaneous membranes–AIDS, immunocompromised–fatal,
40
Q
Varicella-Zoster
A
- chicken pox, skin vesicular eruptions
- latent in dorsal ganglion–shingles in older patients (herpes zoster)
- pain in single dermatome in shingles–localized painful vesicular eruption.
- neutrophil filled vesicles.
- fever, malaise, rash
40
Q
Coccidioidomycosis “Valley fever” “Desert Fever”
A
- “Valley fever” “Desert Fever”
- Coccidioides immitis or Coccidioides posadasii
- Endemic in certain parts of Arizona, California, Nevada, New Mexico, Texas, Utah.
- Flu-like, maculopapular rash,
- Begins with pulm infection, then disseminates, can cause meningitis in immunocompromised.
- Necrotizing, caseous granulomas, non calcifying.
40
Q
Chagas Disease (American Trypanosomiasis)
A
- Rural areas of Mexico, Central America, and South America;
- Flagellate protozoan, insect born zoonosis (kissing bug).
- Bite => Invasion of macrophages / nodular ‘chagoma’
- lesion => dissemination
- Acute illness may kill via myocarditis / encephalitis
- Chronic illness involes GI dysfunction and autonomic nerve degeneration and cardiac failure–years to decades
41
Q
Campylobacter jejuni
A
- microaerophilic, curved, gram(-) rod (similar to vibrios) self-limited
- spread through contaminated food/water + fecal-oral route
- most common cause of bacterial diarrhea in developed world–2 million annual cases in US -affects farm animals–huge economic losses
- causes superficial enterocolitis–terminal ileum and colon with focal necrosis of interstitial epithelium and acute inflammation -severe cases: ulcers and patchy inflammatory exudates (necrotic cells, fibrin, neutrophils)
- watery stools, gross blood containing stools
- associated with Guillain-Barre syndrome (autoimmune peripheral neuropathy)
41
Q
Taeniasis/Cysticercosis (Taenia solium)
A
- Taenia Solium = Brain Cysts
- Ingestion of Larvae (Meat) => Gut Tapeworm
- Pernicious anemia
- Mostly asymptomatic
- Humans shed eggs in fecal matter.
- Ingestion of Eggs (Fecal) => Disseminated Cysts to muscle and brain
- Eggs create a massive inflammatory response. “Swiss cheese brain”
42
Q
Malaria (Plasmodium sp: P. falciparum, P. vivax, P. ovale, P. malariae)
A
- Mosquito-born, hemolytic, febrile illness.
- obligate intracellular parasite-replicate, kill human cells
- Equitorial regions (tropics)
- P. falciparum tends to be worst.
- Human reservoire; gametocytes are in human blood and taken up by mosquito
- Reproduce sexually in mosquito = > sporozoites
- Trasmitting to human via bite; go to the liver and form merozoite, perform asexual division.
- Merozoites can invade/multiply within/destroy RBCs. => hemosiderin-laiden Macrophages seen.
- Hepatosplenomegaly
- clumped, infected erythrocytes block blood vessels–hemorrhages, obstruction–acute renal failure with renal blood vessels, intravsascular hemolysis leads to hemoglobinuric nephrosis (blackwater fever)
43
Q
Glanders
A
- Rare, granulomatous disease.
- Zoonotic; associated with horses.
- Burkholderia mallei aka pseudomonas mallei
- Transmission via cuts in the skin, via musoca, or inspiration.
- Nodular lesions in the lungs and ulceration of the mucous membranes in the upper respiratory tract
- Acute bacteremia => Almost always fatal. Generally a 50% mortality rate and very small minimum infectious dose.
45
Q
Scrub Typhus
A
- Orientia tsutsugamushi, a Gram-negative α-proteobacterium of Rickettsia family.
- Transmitted by Chigger (mites) bite, leaving a black eschar that helps with diagnosis.
- Endemic to parts of Russia, Korea and Japan.
- Can be fatal without treatment.
- Similar effects to those above.–obligate intracellular pathogen–infects endothelial cells
46
Q
Babesiosis
A
- Tick-born, malaria-like disease.
- Typically non fatal (self-limited) in healthy; but immuncompromised/splenectomy => complications
- Reproduce in red blood cells (hemolytic anemia), where they can be seen as cross-shaped inclusions (fourmerozoites asexually budding
- Seen in Europe and North America
47
Q
Salmonella Enterocolitis
A
- gram(-) rod, facultatively anaerobic
- SELF-LIMITED -spread by fecal-oral route, contaminated foodstuff
- proliferate and invade enterocytes in ileum and colon-acute inflamation and some superficial ulceration
- diarrhea (self-limited), nausea, vomiting, abdominal cramping, fever–food poisoning: takes 12-48 hours to manifest (no exotoxin production like S. aureus)
- antibiotics rarely improve clinical course
- major cause of childhood mortality in 3rd world countries (lack of oral rehydration therapy)
47
Q
Chlamydia pneumoniae
A
- Acute, self-limiting.
- P2P droplet spread.
- fever, sore throat, cough
47
Q
Visceral Larva Migrans / Toxocariasis (Toxocara canis & T. catis)
A
- ingestion of fecal contaminated food (from dogs/cats)
- hypereosinophilia, pneumonitis, hypergammaglobulinemia
- cheif symptom: loss of vision in one eye.
- usually Self-limited
49
Q
Onchocerciasis / “river blindness” (Onchocerca volvulus)
A
- Transmitted by fly bite.
- Onchocerca volvulus is the nematode, which carries a bacterial endosymbiont: Wolbachia pipientis, which causes a severe immune response that can cause blindness.
- inlammatory response causes damage to cornea, choroids, retina
51
Q
Toxoplasmosis (T. gondii)
A
- obligate intracellular pathogen
- mostly asymptomatic, problem for immunocompromised and fetus-necrotizing disease.
- Undercooked pig meats, cat litter, cats shed oocysts in their feces.
- Convert to tachyzoites inside intermeidate-host and replicate inside specialized vacuoles
- Immune response causes conversion to bradyzoites, which are associated with cyst formation, especially in CNS and muscle.
- Associated with developmental defects in fetus and neuropsychiatric disorders.
- Encephalitis produced in immunocompromised hosts
- Lymphadenopathy in immunocompetent hosts
52
Q
Granuloma Inguinale (Calymmatobacterium granulomatis)
A
- small, encapsulated, nonmotile, gram(-) bacillus
- Granuloma inguinale: chronic, superficial ulceration of genitalia and inguinal and perianal regions
- lesion is granulation tissue–macrophages, plasma cells, neutrophils and lymphhocytes
- Donovan bodies: interspersed macrophages containing bacteria
- genital elephantiasis: obstruction of lymphatics–thickening of skin and edema (NO BUENO)
53
Q
Endemic (Murine) Typhus
A
- Caused by Rickettsia Typhi
- Transmitted by flea; rodent pool.
- Similar phenotype to epidemic louse-bourne typhus, but less dangerous.
-Flea feces can be inhaled–pulmonary infection
54
Q
Monkeypox
A
- similar to smallpox, milder.
- fever, headache, lymphadenopathy, malaise, myalgia, back ache.
55
Q
Yersinia enterocolitica + pseudotuberculosis
A
- gram(-) coccobacillus, facultative anaerobes
- fecal-oral route and contaminated water + milk.
- painful diarrhea
- enerocolitica: contaminated meat; proliferates in ileum and invades mucosa–necrosis and ulceration of Peyer patches–fever, diarrhea (bloody), and abdominal pain (can be confused with appendicitis); rare septicemia
- 50% mortality rate in those persons
- pseudotuberculosis (Far East scarlet-like fever): contact with infected animals, penetrates ileal mucosa, localizes in ileal-cecal lymph nodes and causes abscesses and granulomas in lymph nodes, spleen, and liver–fever, diarrhea, and abdominal pain (appenicitis mimic)
57
Q
Bejel (endemic syphilis) (Treponema pallidum endemicum).
A
- gummas in skin, airways, bone
- transmission is mouth-to-mouth, breast-to-mouth, or utensil-to-mouth
- usually begins in childhood as a small mucous patch, often on the interior of the mouth, followed by the appearance of raised, eroding, Pyogenic lesions on the limbs and trunk. Periostitis (inflammation) of the leg bones is commonly seen, and gummas of the nose and soft palate develop in later stages.
- Mediterrenian/West Africa
59
Q
Parainfluenza Virus
A
-Epidemiology: Common in children under 3 years. Spread from person to person through respiratory aerosols and secretions. Highly contagious. Isolated from 10% of young children with acute respiratory tract illness.
-CROUP Pathology: Infect and kill ciliated respiratory epithelial cells and cause inflammatory response. Extends to lower respiratory tract in young children causing bronchiolitis and pneumonitis.
Clinical Features: Local edema of laryngotracheitis compresses upper airway to obstruct breathing and cause croup (laryngotracheobronchitis causing inspiratory stridor and barking cough). Causes fever, hoarseness, and cough. Symptoms mild in adults.
60
Q
Severe Acute Respiratory Syndrome (SARS)
A
- SARS-associated coronavirus (SARS-CoV) from bats.
- aerosol respiratory spread -alveolar damage (multinucleate cells without viral inclusions) -fever, headache, cough, dyspnea + some liver involvement (rare)
- higher fatality in elderly
61
Q
Cytomegalovirus
A
- infects lymphocytes and monocytes–Infectious Mononucleosis
- symptomatic in immune suppressed patients (as is EBV)
- encephalitis, pneumonitis, GI hemmorhage
62
Q
Atypical pneumonia (Mycoplasmal pneumoniae) = Walking pneumonia
A
- Light or non-productive cough.
- Non-lobar, very small localizations. “Patchy consolidation” often in lower lung.
- Caused by unexpected organisms (Not: Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis)
- Caused by atypical bacteria, viruses, fungi,
- smallest free-living prokaryotes
64
Q
Dermatophyte Infections
A
- obtain nutrients from keratin–common and benign
- Athlete’s foot or tinea pedis
- Ringworm of the body or tinea corpora
- Facial ringworm or tinea faciei
- Blackdot ringworm or tinea capitis
- Scalp ringworm or tinea capitis
- Ringworm of the hands or tinea manuum
- Ringworm of the nail, Onychomycosis, or tinea unguium
66
Q
Neisseria meningitides (Meningococcus)
A
- paired, bean-shaped, gram(-) cocci
- epidemic in crowded areas (military barracks)
- P2P spread: respiratory droplets
- confined to CNS or disseminated
- fulminant fever, stiff neck, headache
- meningococcal sepsis: fever, shock, mucocutaneous hemmorhages, diffuse vascular endothelium damage, petechiae, purpura
- Rare: vasculitis, thrombosis–Waterhous-Friderichsen Syndrome (adrenal hemorrhagic necrosis)
66
Q
Leptospirosis
A
- Transmission: Water w/ animal urine contacts breaks in the skin.
- Usually mild and self-limited, sever forms cause hepatic and renal failure
- Leptospiremic phase: 1-2 weeks of nonspecific fever, shaking chills, headache, myalgia that resolve on their own
- Immune phase / Weil disease: 3 days after the leptospiremic phase, symptoms return with vasculitis, hemorrhage, meningitis (CNS pleocytosis), liver and kidney failure, shock and death.
- Mortality of Weil disease is 5-30%
68
Q
Mumps
A
- Epidemiology: Present worldwide–disease of childhood. Highly contagious–infects 90% of exposed with 60-70% showing symptoms. Live attenuated viral vaccine prevents mumps.
- Pathology: Viral infection of respiratory epithelium–necrosis. Disseminates through blood and lymphatic systems to salivary and parotid glands, CNS, pancreas, and testes. 50% cases involve CNS. Epididymoorchitis (unilateral; no sterility) present in 30% males (swollen to three times normal size)–causing local infarctions. Swollen glands and ducts lined by necrotic epithelium and interstitium infiltrated by lymphocytes.
- Clinical Features: Fever and malaise followed by painful swelling of salivary glands, one or both of parotids. Symptomatic meningeal involvement manifests as headache, stiff neck, and vomiting. Prior to vaccination, mumps was leading cause of viral meningitis. Patients exhibit elevated serum amylase levels though sever pacreatitis is rare.
70
Q
Listeriosis (Listeria monocytogenes)
A
- reservoir: many species of mammals and birds–rare spread from animal to human
- spread: unpasteurized milk and dairy products
- evades intracellular + extracellular host responses: acidic phagosome activate listeriolysin O exotoxin–escape into cytoplasm and usurps cytoskeleton to form portrusions to dock with other cells (spread without staying in extracellular environmentz)
- Pregancy listeriosis: lead to abortion or premature delivery
- Septicemic listeriorsis: severe febrile illness in immunocompromised–shock and DIC: death without treatment (heavy duty antibiotic course needed)
- Self-limited in healthy host
71
Q
Bartonellosis (Bartonella bacilliformis)
A
- aka Carrion’s disease
- gram(-) pleomorphic bacteria
- vector: sandflies of Peru, Ecuador, Colombia
- Oroya fever: acute hemolytic anemia–untreated leads to 40% mortality rate
- verruga peruana: dermal eruptive phase–chronic skin condition that is self-limited and follows acute anemic phase
72
Q
Tropical Phagedenic Ulcer (Bacillus fusiformis and Treponema vincentii)
A
- a.k.a Tropical Foot, fusospirochetal infection
- Follows trauma (lesions) in the tropics, malnutrition is a factor.
- Painful leg legion with necrosis, sloughing of skin, and gray putrid exudate -May be complicated by tibial osteomyelitis and squamous cell carcinoma
- Deep wounds that persist for years, often need reconstructive surgery to fix
73
Q
Cryptococcosis (C. neoformans) - encapsulated
A
- Inhaled- natural reservoir is pigeon droppings
- Impaired cell-mediated immunity common (AIDS, hodkins disease, leukemia)
- CNS = site of primary infection–meningitis. Also causes progressive pulmonary disease
- Fatal without treatment
- Proteoglycan capsule is critical for virulence, - stains poorly with H&E - stains with mucicarmine
- India Ink stain of CNS infection
73
Q
Schistosomiasis (Schistosoma mansoni, S. japonicum, S. haematobium)
A
-Most important human helminthic infection, very disabling.
-Intense inflammatory response, damage to nearby tissue, usually Liver, GI, or bladder, where it causes granulomas and dysregulated growth (polyps in colon, sq cell carcinoma in bladder).
-Asexual reproduction in snail.
-Penetrates human skin as schistosomula.
-Lays eggs: These cause the inflammatory response.
Diagnosed based on eggs in feces.
-Generally self-limited
74
Q
Actinomyces (Actinomycosis)
A
- filamentous, anaerobic, Gram(+) commensual saprophytes present in oropharynx, GI tract, vagina–requires trauma to cause disease
- Cervicofacial: jaw injury or after dental surgery–leads to purulent abscesses in jaw. “lumpy jaw” -form sulfur granules made of Splendore-Hoeppli material (tangled masses of branching filaments in polysaccharide protein matrix)
- Sinus tracts that penetrate lobe to lobe in pulmonary infections
- progressive, slow growing (anaerobic), disease that is well controlled by antibiotics
- Fatal if untreated
76
Q
Mycobacterium avium-intracellulare Complex (MAI)
A
- Spreads by aerosols from infected water (or infected food, soil)
- Immunocompromised older people (⅓ of AIDS patients!). COPD predisposes.
- Begins in lungs - causes TB like pulmonary cavities and caseating granulomas (but slow progressing)-years to decades. Macrophages engulf (but dont kill) bugs, then spread throughout body
- Antibiotics may control but not cure.
77
Q
Rubeola (Measels)
A
- Spread via respiratory tract and secretions (person-person) -Necrosis of respiratory epithelium, with predominate lymphocytic infiltrate.
- Warthin-Finkeldey giant cells (up to 100 nuclei).
- fever, rhinorrhea, cough, and conjunctivitis. -Progresses to characteristic mucosal and skin lesions (Koplik spots) develope -Subacute sclerosing panencephalitis (SSPE) -more deadly in immunocompromised
79
Q
Chlamydiae trachomatis Infections
A
- most common STD
- Intracellular, cant make ATP -Elementary body attached to cell and becomes endocytosed
- Reticulate body becomes active inside cell, pirates the cell machinery.
- Genital and Neonatal Infections
- Serovars D through K -Asymptomatic in approx 60% women.
- Inflammation of GU tracts, exudate, PID
- Generally non lethal, can cause permanent damage to reproductive system.
- Lymphogranuloma Venereum
- Serovars 1 through 3
- Buboes or abscesses in the groin (inguinal) region where draining lymph nodes are located, progress to necrotizing lymphadenitis.
- Often seen with HIV.
- Trachoma
- Serovars A,B,C
- Leading cause of blindness in underdeveloped.
- Neonatal exposure from mom.
- Effects eyes: characteristic roughening of the inner surface of the eyelids. -Painful, Can lead to visual impairmnent.
80
Q
Atypical Mycobacteria
A
- Not common, may be inhaled, ingested, or inoculated
- M. kansasii - granulomatous disease similar to MAI in older people
- M. scrofulaceum - granulomatous, cervical lymphadenitis in young children
- M. marinum - granulomatous or pyogenic, localized skin lesions - from water (pools)
- M. chelonae or fortuitum - painless abscesses from trauma that ulcerate and then heal
81
Q
Q Fever
A
- Coxiella burnetii
- From animals–inhalation of aerosolized dropletts
-phagocytosed and proliferation inside macrophages.
- Typically a self-limited systemic infection, particularly lungs and liver.
- Granulomatous hepatomegaly.
82
Q
Haemophilus influenzae
A
- aerobic, pleomorphic, gram(-) coccobacillus, nonencapsulated, capsulated(Type B): most virulent
- P2P spread: respiratory droplets and secretions
- Normal flora of oropharynx -pyogenic infection, MENINGITIS (#1 cause in
- broncopneumonia, epiglottitis (obstruct airway), septic arthritis (bacteremic), facial cellulitis (bacteremic)
- vaccine: nearly eliminated infantile meningitis
83
Q
Brucellosis (Brucella)
A
- Facultative intracellular parasites causing chronic disease, which usually persists for life.
- four types: goats/sheep, cattle, swine, dogs
- enter through lungs, through skin, oropharynx
- produces UNDULANT FEVER (waxes and wanes)
- multiply in macrophages (lymph nodes, spleen, liver): multi-organ granulomas
- common complications: spondylitis of spine, meningitis, endocarditis–treat with tetracycline -usually self-limited. mortality
84
Q
Hookworms (Necator americanus, Ancylostoma duodenale)
A
- penetrate human epidermis on contact-enter venous circulation
- Duodenale = Asia / Mid East / Africa
- Americanus = Americas, Southeast Asia, Subsaharran africa.
- GI inflammation, iron deficiency anemia
- Most common cause of chronic anemia worldwide.
85
Q
Anthrax (Bacillus anthracis)
A
- Gram-positive, endospore-forming, rod-shaped bacterium
- spore form in dead animals/soil and reservoir in goats/sheep/cattle/dogs/pigs/horses
- spread through inhalation, breaks in skin, ingestion with germination in body
- Malignant pustule: Cutaneous form (most common) papule/ulcer–lymphadenitis can lead to septicemia. (without dissemination–self-limited no complications)
- Pulmonary: “woolsorter’s disease” respiratory failure and shock within 24-48 hours.
- Septicemic: DIC, exotoxin depresses respiratory center–antibiotics ineffective against exotoxin
- Gastrointestinal: rare, eating contaminated meat: stomach + bowel ulceration–death caused by fulminant diarrhea and massive ascites
86
Q
Amebiasis (Entamoeba histolytica
A
- Active form (trophozoite) in human and feces
- Cyst form is usually ingested from environment / fecal oral.
- Large Intestine, bleeding more likely.
- Invasive => May feature bloody / leukocytes in stool, metastisis = >Liver
- ameboma: complication, when amebae invade through intestinal wall-inflammatory thickening of bowel resembling colon cancer.
88
Q
Creutzfeldt-Jakob Disease
A
- sporadic, familial, iatrogenic (from pituitary of cadaveric victims)
- neurodegenerative -myoclonus, behavioral changes, dementia
- New Variant (vCJD): associated with mad cow
- genetic susceptibility (met-met at codon 129 of gene PRNP -fatal (no cure)
88
Q
Legionella pneumophilia
A
- small, aerobic bacillus, gram(-)
- respiratory spread: aerosols of infected sources, NOT CONTAGIOUS
- pneumoina: Legionaire’s Disease (life-threatening) and Pontiac fever (milder, self-limiting)
- proliferate inside resident macrophages (granulomatous)–macrophages show eccentric nuclei pushed aside by vacuoles containing L. pneumophila
- alveolar necrosis, fever, nonproductive cough followed by hypoxia leading to death.
- Silver grain stain, Urine antigen test for diagnosis
90
Q
Cat-Scratch Disease (Bartonella henselae)
A
- proteobacteria
- spread from cat scratches inoculated skin or contact with eye.
- Self-limited granulomatous and purulent lymphadenitis.
- Parinaud oculoglandular syndrome secondary to conjunctival infection
91
Q
Clostridium difficile
A
- obligate anaerobe, spore forming, gram(+)
- acute necrotizing infection of small bowel and colon responsible for antibiotic-associated diarrheas (clindamycin most responsible)
- Produces cytotoxins A + B
- opportunistic–resides in colon flora
- pseudomembranous colitis
92
Q
Leishmaniasis (Leishmania spp.)
A
- Via sandfly bite.
- proliferate in macrophages–amastigotes
- Tropic/Subtropic, overcrowding.
- Skin soars, may progress to disseminated disease, splenomegaly.
- kala azar=visceral leishmaniasis “black sickness”-viscera overwhelmed by build up of infected macrophages–disrupts organ architecture with sheets of parasitized macrophages.
- kala azar is fatal: Requires treatment if disseminated.
93
Q
Chromomycosis
A
- tropics and subtropics
- barefooted agricultural workers
94
Q
Trichinosis (Trichinella spiralis)
A
- Inadequatly cooked or encysted meat; PORK.
- Survives in human skeletal muscle, myositis (diaphragm, ocular muscles, tongue, intercostals, deltoids, gastrocnemius), calcifications
- Classic sign: periorbital edema, swelling around the eyes, which may be caused by vasculitis.
- Extreme eosinophilia (>50% of leukocytes)
- May have CNS or cardiac involvement
96
Q
Corynebacterium diphtheriae
A
- aerobic, gram(+) rod, pleomorphic
- P2P spread: respiratory droplets + oral secretions
- diphteria exotoxin
- thick, gray, leathery membranous lesions from respiratory epithelium (necrotic debris, fibrin, neutrophils,
- fever, sore throat, malaise -treated with antitoxin and antibiotics
- most in western world immunized
- peripheral nerve demyelination w/ neural involvement
97
Q
Streptococcus Pneumoniae (pneumococcus)
A
- Gram(+) cocci
- pneumonia, sinusitis, otitis media, meningitis
- normal flora in oropharynx (opportunist)
- infection follows cold or influenza
- insults such as smoking and alcohol
- capsule blocks opsonization by complement C3b (inhibits macrophages, antibody needed to kill) -Self limiting, Not severe
99
Q
Leprosy (Mycobacterium leprae)
A
-Spreads person to person through intimate contact - respiratory tract or open wounds
-Proliferates in areas of lower body temperature (hands and face)
-Infection occurs in 5% of exposed people and is either tuberculoid or lepromatous
Tuberculoid = Moderate: few lesions, dermal granulomas with sensory loss (not caseous). Reflects appropriate TH1 activation
Lepromatous = Severe: foamy macrophages act as incubators and form globi. Form diffuse, tumor like lesions of skin, eyes, testes, nerves, lymph nodes and spleen. Results from deficient TH1 activation.
100
Q
Pinta (Treponema carateum)
A
- spirochete, invade macrophages
- Skin-to-skin transmission
- Mexico, Central America
- Colored spots, scaly/flakey, disease limited to the skin; may leave behind areas of hyperpigmentation
101
Q
Herpes Simplex Virus 1 and 2
A
- HSV1: oral secretions
- HSV2: genital secretions
- painful ulcerating lesions on skin or mucous membranes
- Herpes encephalitis and hepatitis (rare HSV1)
- neonatal Herpes–serious complication of maternal genital herpes (high mortality)
- acyclovir effective
102
Q
Escherichia coli
A
- antigenically diverse, aerobic (facultatively anaerobic), gram(-) rod, most commensal and opportunistic
- synthesize vitamin K2, virulence after plasmid transfer
- 90% of all urinary tract infections -bladder mucosa infection–dysuria, pyuria (leukocytes in urine)
- Immunocompromised: Pneumonai, sepsis
- neonatal meningitis: colonizes vaginal canal
- Four strains:
- ENTEROTOXIGENIC: traveler’s diarrhea from contaminated water and food, self-limited (Africa, Latin America)–produce 3 enterotoxins–secretory dysfunction of small bowel (one similar to cholera-adenylyl cyclase, other acts on guanylyl cyclase)
- ENTEROPATHOGENIC: diarrheal illness in tropical regions among infants and children, spread from contaminated food and water, deforms microvilli of intestinal epithelial cells, fever + malaise
- ENTEROHEMORRHAGIC: bloody diarrhea, fever, cramping abdominal pain, hemolytic-uremic syndrome (anemia, acute kidney failure, thrombocytopenia), contaminated meat/milk, enterotoxin similar to Shigatoxin
- ENTEROINVASIVE: food-borne DYSENTERY, indistinguishable from shigella (similar toxin to shiga toxin)-self-limited, invades and destroys mucosal cells of ileum and colon. abdominal pain, fever, tenesmus (feeling of incomplete defecation), bloody diarrhea. week long illness
104
Q
Blastomycosis (Blastomyces dermatitidis)
A
- Very similar to coccidiomycosis, granulomatous, but also suppurative pulmonary dissease
- Endemic to Midwest, Mississippi river and Ohio river basins, and around the Great Lakes.
- Skin (>50%) and bones (>10%) are most common sites of extrapulmonary involvement.
- Usually self-limited (1/3 of patients)
105
Q
Rotavirus
A
- Epidemiology: spreads by oral-fecal route. Most common amongst children. siblings, parents, playmates, food, water, and surfaces face contamination. 6 months to 2 years is peak age of infection. (all infected by age 4). 100 deaths in young children in US. 1 million deaths worldwide.
- Pathology: confined to duodenum and jejunem, where there is shortening of intestinal villi and mild infiltrate of neutrophils and lymphocytes
- Clinical Features: Vomiting (2-3 days duration), fever, abdominal pain, and profuse watery diarrhea (5-8 days duration). Without fluid replacement, diarrhea can produce fatal dehydration in young children.
107
Q
Epidemic (Louse-Borne) Typhus
A
- Caused by Rickettsia prowazekii,
- Transmitted by lice, often during disasters, war, or in prisons; human pool.
- Obligate intracellular pathogen
- Early stage = Febrile
- Later = A rash begins on the chest (infects capillary endothelial cells) about five days after the fever appears, and spreads to the trunk and extremities.
108
Q
Influenza Type A, B, C
A
- Epidemeology: 10-40 million annual cases for 35,000 deaths. Highly contagious and epidemics spread world wide. Hemagluttinin (H) and Neuraminidase (N) designate serotype.
- Pathology: Necrosis and desquamination of ciliated respiratory tract epithelium–lymphocytic infiltrate. infection of lungs leads to necrosis and sloughing of alveolar lining cells.
- Clinical Features: Rapid onset of fever, chills, myalgia, headaches, weakness and nonproductive cough. Upper respiratory infection Deaths from both influenza and its complications. Vaccine 75% effective in preventing influenza.
109
Q
Relapsing Fever (Borrelia recurrentis)
A
- Epidemic fever disease from lice, caused by Borrelia recurrentis: high untreated mortality
- Endemic version is from ticks, many species
- General symptoms: fever, lethargy, arthralgia, headache, myalgia, petechiae -More specific symptoms: splenomegaly with miliary microabscesses, hemorhages, hepatomegaly because the spirochetes live in liver sinusoids → inflammation
- Sickness comes and goes abruptly in 1-2 week long waves, each time the duration is shorter and symptoms are milder.
- Spirochetes also change their antigenic coats in between each febrile period
- can be fatal
110
Q
Staphylococcus Aureus (coagulase positive)
A
- natural flora on skin–innoculation following injury
- leading cause of infective endocarditis -furuncles, carbuncles, scalded skin syndrome (desquamantion), osteomyelitis, bacterial arthritis
- Septicemia, TSS, food posioning,
- MRSA-antibiotic resistance plus virulence factors (toxins + proteolytic enzymes) encoded on plasmids.
112
Q
Strongyloidiasis / Threadworm (Strongyloides stercoralis)
A
- penetrate human epidermis
- most cases asymptomatic, lethal disseminated disease in immunocompromised persons.
- reproduce in human hosts-autoinfection (rhabditiform larvae become infective filariform within host’s intestine and repenetrate perianal skin–new parasitic cycle
- Immunocompromised: autoinfection greatly increased-penetrate intestinal walls and disseminate leading to ulceration, edema, and severe inflammation leading to sepsis from gram(-) bacteria-FATAL
113
Q
Chancroid (Haemophilus ducreyi)
A
- gram(-) bacillus, histology looks like school of fish
- P2P: sexually
- Chancroid: leading cause of genital ulcers in 3rd world countries (facilitate spread of HIV)
- opportunistic: enters through breaks in skin
- painful, unilateral, suppurative, inguinal lymphadenitis (bubo)
- erythromycin: effective treatment
114
Q
Adenovirus
A
- Pathology: necrotizing bronchitis and bronchiolitis, with sloughed epithelial cells and inflammatory infiiltrate (lymphocytic) fill damaged bronchioles. Interstitial pneumonia is characterized by areas of consolidation with extensive necrosis, hemorrhage, and mononuclear inflammatory infiltrate. Intracellular inclusions, smudge cells and Cowdry type A inclusions involve bronchiolar epithelial cells and alveolar lining cells.
- Clinical Features: necrotizing bronchitis and bronchiolitis. Adenovirus type 40 + 41 infect colonic and small intestinal epithelial cells–cause diarrhea in both immunocompetent and compromised victims. AIDS patients susceptible to Adenovirus type 35–urinary tract infections.
115
Q
Salmonella typhi
A
- P2P spread (chronic carriers commonly old women with gallstones or biliary scarring), and contaminated water/food–dairy and shellfish, oral-fecal route rarer
- granulomatous infection: proliferation inside infected macrophages
- Typhoid fever (SEVERE): degeneration of intestinal epithelium brush border (Peyer patch hypertrophy as well)–capillary thrombosis with ulcerated bowel tissue leading to infectious peritonitis; Systemic dissemination: focal granulomas in liver, spleen (typhoid nodules-macrophages with ingested bacteria,erythrocytes, dead lymphocytes)
- 10-14 day incubation period
- Signs: Bacteremia/invasion: daily increase in temperature (IL-1 + TNF), malaise, arthralgias, abdominal pain–Fastigium: fever/malaise increase–septicemia from release of endotoxin from dead bacteria and hepatomegaly and splenomegaly. Fever abates over weeks to months -10-20% mortality in untreated patients (complications including pneumonia)
- Typhoid antitoxin curative if given within 3 days of fever onset.
116
Q
Group B Streptococci
A
- Gram(+) cocci
- Neonatal Pneumonia, meningitis, and sepsis
- 30% infected infants die (1000’s infected yearly)
- Normal vaginal flora in 10-30% women
- spread to infant through birth canal
- Risk factor is low level of maternal IgG antibodies
117
Q
Bordetella Pertussis
A
- Gram(-) coccobacillus
- highly contagious, P2P: respiratory aerosols
- tracheobronchitis with necrosis of ciliated respiratory epithelium (acute inflamed response)
- Whooping cough: paroxysmal stage
- catarrhal stage: upp resp illness w/ low fever, runny nose, conjunctivitis, cough
- vaccine: unimmunized–50 million cases w/ 1 million deaths per year.
- secondary bacterial pneumonia–causes death
118
Q
Klebsiella (pneumoniae) + Enterobacter
A
- short, encapsulated, facultative anaerobic, gram(-) rods
- necrotizing lobar pneumonia with cavitations
- 10% of nosocomial infections: P2P spread
- patients with COPD, endotracheal tubes, catheters, and immunosuppressed.
- complication from influenza or other viral infections
- characteristic THICK MUCOID SPUTIM
- can lead to fulminating, deadly septicemia–requires aggressive antibiotic treatment
119
Q
Cutaneous Larva Migrans (“Creeping eruption”)
A
- spread through skin on contact (dogs and cats major source of of disease)
- severe, itching, inflammation
120
Q
Fatal familial insomnia
A
- inheirited, rare disorder
- progressive degree of insomnia to sleeplesness
- autonomic instability, motor system degeneration, spongiform changes (like CJD)
121
Q
Botulism (Clostridium Botulinum)
A
- neurotoxin present in improperly canned food (blocks acetylcholine release): Don’t feed newborns honey
- descending paralysis, blurred vision
- untreated: lethal
- antitoxin- 25% mortality
122
Q
Primary Amebic Meningoencephalitis
A
- Naegleria fowleri “Brain eating ameoba”: free-living, soil ameba
- Rare, but almost always rapidly fatal: fulminant disease-fever, nausea, vomiting, headache to deterioration of mental status in matter of hours.
- invades via nasal epithelium/olfactory bulbs.
- Swimming pools
- Neti-pots (for cleaning out your sinuses)
123
Q
Loiasis “African Eye Worm”
A
- Mango fly bite transmites loa loa (round worm), which travels to the conjunctiva, where it can be readily seen in patient.
- Does not cause blindness
- rarely lethal (sudden + diffuse cerebral ischemia)
- usually self limited with mild CNS involvement
124
Q
Aspergillosis
A
-spores (conidia) inhaled
-Allergic bronchopulmonary aspergillosis: restricted to
asthmatics, spores can germinate in airways and cause long-term antigen exposure → exacerbation and infiltrates
-Aspergilloma (fungus ball): Occur in old TB cavities. Cavity wall is collagenous connective tissue with lymphs and plasma cells. Usually left untreated if asymptomatic.
-Inasive Aspergillosis: Occurs when neutrophil count is low (steroids, leukemia). Produces lung and pleural infarcts, but often spreads to blood and causes disseminated infec tion and thrombosis. Usually fatal, antifungals may help.
