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,
