Bacteriology Flashcards
1
Q
Staphylococcus
A
- Gram positive cocci in clusters
- Protein A binds Fc-IgG, inhibiting complement activation and phygocytosis
- causes
- inflammatory disease: skin infection, organ abscesses, pneumonia, endocarditis, osteomyelitis
- Toxin mediatad disease: TOSS-1, scalded skin syndrome ( exfoliative toxin), rapid onset of food poisoning (enterotoxin)
- MRSA: serious nosocomial and community acquired infections. Resistant to methicillin d/t altered penicilin binding protein
- Toxins
- TSST: super antigen that binds MHC II and TCR leading to polycolonal T cell activation ( fever, vomiting, shock, end organ failure
- Food poisoning: ingestion of preformed toxins ( 2-6 hr incubation). Heat stable toxin is not destroyed by cooking
2
Q
Staphylococcus Epidermidis
A
- Gram positive, cocci, catalase positive, coagulase (-), novobiocin sensitive
- infects prostatic devices and intravenous catheters by producing an adherent biofilm
- component of normal skin flora
- contaminates blood culture
3
Q
Staphylococcus Saprophyticus
A
- Gram positive, Cocci, Catalase positive, Coagulase negative
- novobiocin resistant
- second most common cause of UTI in young women ( after E. coli)
4
Q
Streptococcus pneumoniae
A
- Gram positive, diplococci, catalase negative, alpha hemolytic
- Causes
- Meningitis
- Otiti media (children)
- Pneumonia
- sinusitis
- encapsulated (no virulence without capsule)
- IgA protease
*
5
Q
Viridans streptococci
A
- Gram positive, Cocci, catalase negative, alpha hemolysis
- no capsule, optochin resistant, bile insoluble
- normal flora of oropharynx and cause dental carries (S. mutans) and subcute bacterial endocarditis at damaged valves
6
Q
Streptococcus pyogenes
A
Gram positive, Cocci, Catalase negative, Beta hemolysis
- bacitracin sensitive
- Causes
- Pyogenic: pharyntitis, cellulitis, impetigo
- Toxigenic: scarlet fever, toxic shock syndrome, necrotizing faciitis
- Immunologic: rheumatic fever, acute glomerulonephritis
- Antibodies to M proteins enhance host defenses but can give rise to rheumatic fever
- JONES criteria
- joints
- carditis
- nodules
- erythema nodosum
- syndenham chorea
- impetigo more commonly preceeds glomerulonephitis than pharyngitis
- Scarlet fever: scarlet rash with sandpaper like texture, straberry tongue, circumoral pallor
7
Q
Streptococcus agalactiae
A
Group B strep
Gram positive, Cocci, chains, catalase (-), beta hemolytic
- Bacitracin resistant
- Colonizes vagina
- Causes ( mainly in babies)
- penumonia
- meningitis
- sepsis
- Produces CAMP factor which enlarges the area of hemolysis formed by S. aureus.
- Hippurate test positve
- screen pregnant women at 35-57 weeks: positive cultures requires intrapartum penicillin prophylaxis
8
Q
Enterococci
A
Gram positive, Cocci, catalase negative, no hemolysis, grown in 6.5% NaCl and bile
- E. faecalis and E. faecium
- normal colonic flora that are penicillin G resistant
- cause UTI, biliary tract infections, subacute endocarditis
- VRE: cause nosocomial infection
9
Q
Streptococcus bovis
A
Gram positive, cocci, catalase negative, grows in bile, does not grow in 6.5% NaCl
- colonizes the gut
- can cause bactermia and subacute endocarditis in colon cancer patients
- Bovis in the blood= cancer in the colon
10
Q
Corynebacterium dipthaeriae
A
- Diphtheria
- exotoxin encoded by beta prophage
- inhibits protein synthesis via ADP- ribosylation of EF-2
- Symptoms
- pseudomembranous pharyngitis
- lymphadenopathy
- myocarditis
- arrythmia
- Gram postive rod
- metachromatic (red and blue) granules
- Elek test for toxin
- black colonies on cystine tellurite agar
ABCDEFG
- ADP ribosylation
- Beta prophage
- Corynbacterium
- Diptheriae
- Elongation factor 2
- Granules
11
Q
Spore forming bacteria
A
- Bacillus anthracis (G+)
- Clostridium perfringens (G+)
- C. tetani (G+)
- B. cereus
- C. botulinum
- Coxiella burnetii
12
Q
Clostridium Tetani
A
G (+), spore-forming, obligate anaerobic bacilli
- Produces tetanospasmin
- exotoxin cause tetanus
- tetanus toxin are proteases that cleave releasing proteins for neurotransmitters
- Induces tetanic paralysis
- blocks glycine and GABA release from Renshaw cells in spinal cord
- causes spastic paralysis, trismus (lockjaw), risus sardonicus
13
Q
Clostridium Botulinum
A
G (+), spore-forming, obligate anaerobic bacilli
- Produces preformed, heat labile toxin that inhibits ACh receptor release at NMJ
- causes botulism
- Disease in adults: ingetion of preformed toxin
- Disease in babies: ingestion of spores ( floppy baby syndrome)
- causes flaccid paralysis
14
Q
Clostridium perfringens
A
G (+), spore-forming, obligate anaerobic bacilli
- produces alpha toxin (lecithinase) a phospholipase that causes myonecrosis and hemolysis
- gas gangrene
15
Q
Clostridium difficile
A
G (+), spore-forming, obligate anaerobic bacilli
- Toxin A
- enterotoxin
- binds to brush border of gut
- Toxin B
- cytotoxin
- cytoskeletal disruption via actin depolarization
- pseudomembranous colitis
- diarrhea
- often secondary to antibiotic use
- Diagnosed by detection of one or both toxins in stool
- Tx: metronidazole (Flagyl) or PO vancomycin
16
Q
Bacillus anthracis
A
- Gram positive, spore forming rod
- produces anthrax toxin
- polypeptide capsule (containing D-glutamate)
Cutaneous anthrax
- Boil like lesion–> ulcer with back eschar
- painless, necrotic
- uncommonly progresses to bacteremia and death
Pulmonary anthrax
- inhalation of spores
- flu like symptoms that rapidly progresses to fever, pulmonary hemorrhage, mediastinitis and shock
- woolsorter’s disease: inhalation of spores from contaminated wool
17
Q
Listeria monocytogenes
A
- Facultative intracellular microbe
- acquired by ingestion of unpasteurized dairy produces and deli meats via transplacental transmission or by vaginal transmission at birth
- “Rocket tails”: actin polymerization that allow them to move through cytoplasm and into cell membrane
- Gram positive, produces LPS
- Pregnant women: septicemia, spontaneous abortion
- granulomatosis infantiseptica, neonatal meningitis, meningitis in immunocompromised, mild gastroenteritis in healthy
- Tx: ampicillin in infants, immunocompromised and elderly for meningitis
18
Q
Actinomyces
A
- Gram positive anaerobic
- not acid fast
- normal oral flora
- causes oral/facial abscesses that drain through sinus tracts, forms yellow “sulfur granules”
- Tx: penicillin
19
Q
Norcadia
A
- Gram positive aerobe
- acid fast (weak)
- found in soil
- causes pulmonary infections in immunocompromised and cutaneous infection after trauma in immunocompromised
- Tx: sulfonamides
20
Q
Mycobacterium tuberculosis
A
- acid fast
- sxs: fever, night sweats, weight loss, hemoptysis
- cord factor in virulent strains inhibits macrophage maturation and induces release of TNF-z
- Sulfatides (surface glycolipids) inhibit phagolysosomal fusion
21
Q
Mycobacterium leprae
A
- acid fast bacillus
- infects skin and superficial nerves ( glove and stocking loss of sensation)
- reservoir in US: armadillos
Lepromatous
- diffusely over skin with leonine facies
- communicable
- low cell mediated immunity with humoral Th2 response
- Tx: Dapsone + rifampin+ clofazimine for 2-5 years
Tuberculoid
- limited to few hypoesthetic hairless skin plaques
- high cell mediated immunity with a TH1 type immune response
- Tx: dapson + rifampin for 6 mo
22
Q
A
23
Q
A
24
Q
Neisseria
A
- Gram negative
- diplococci
- ferment glucose and produce IgA proteases
- N. gonorrhoaea is often intracellular
25
Neisseria
Gonococci
* gram negative, diplococci
* no polysaccharide capsule
* no maltose fermentaiton
* no vaccine
* sexually transmitted
* causes
* gonorrhea
* septic arthritis
* neonatal conjunctivitis
* pelvic inflammatory disease (PID)
* Fitz-Hugh-Curtis syndrome
* Condoms prevent sexual transmission
* Erythromycin ointment prevents neonatal transmission
* Tx: ceftriaxone ( azithromycin or doxycycline) for possible chlamdia co-infection
26
Neisseria
Meningococci
* Gram negative, diplococci
* Polysaccharide capsule
* maltose fermentation
* vaccine
* respiratory and oral secretion transmission
* causes
* meningococcemia
* meningitis
* Waterhouse-Friderichsen syndrome
* Prophylaxis: Rifampin, ciprofloxicin, ceftriaxone
* Tx: Ceftriaxone or penicillin G
27
Haemophilus influenzae
* gram negative rod (coccobacillus)
* aerosol transmission
* produces IgA protease
* Culture on chocolate agar requires factors V (NAD+) and X (hematin) for growth
* causes
* epiglottitis
* meningitis
* otitis media
* pneumonia
* Tx:
* mucosal infections: amoxicillin +/- clavulanate
* meningitis: cetriaxone
* Prophylaxis: Rifampin
* Vaccine: type B capsule polysaccharide conjugated to diptheria toxoid (given between 2-18 mo)
28
Legionella pneumophilia
* gram negative rod
* silver stain
* grows on charcoal yeast extract culture with iron and cysteine
* detected by presence of antigen in urine
* aerosol tranmission from environmental water sources habitat ( air conditioning, hot water tanks)
* No person to person transmission
* Tx: macrolide or quinolone
Legionnaire's disease
* severe pneumonia, fever, GI and CNS symptoms
Pontiac Fever
* mild flu like symptoms
29
Pseudomonas aeruginosa
* **_Aer_**obic gram negative rod
* non-lactose fermenting, oxidase positive
* produces pyocyanin (blue-green pigment)
* grape-like odor
* water source
* produces endotoxin ( fever, shock) and exotoxin A ( inactivates EF-2)
* associated with
* wound and burn infections
* **P**neumonia (CF)
* **S**epsis
* **E**xternal otitis (Swimmer's ear)
* **U**TI
* **D**rug use
* Diabetic **o**steomyelitis
* hot tub folliculitis
Ecthyma gangrenosum
* rapidly progressive necrotic cutaneous lesions caused by pseudomonas bacteremia
* typically seen in immunocompromised pts
Tx: aminoglycoside + extended spectrum penicillin (piperacillin, cefepime, imipenem, meropenem)
30
E. Coli
Gram negative, Rod, Lactose fermenter (fast)
* Virulence factors
* fimbriae: Cystitis and pyelonephritis
* K capsule: pneuonia, neonatal meningitis
* LPS endotoxin: septic shock
31
E. coli:
EIEC
Microbe invades intestinal mucosa and causes necrosis and inflammation
* invasive
* dysentery
32
E. coli:
ETEC
produces heat labile and heat stable enterotoxins
* no inflammation or invasion
* Traveler's diarrhea (watery)
33
E. coli:
EPEC
* No toxin produced
* adheres to apical surface, flattens villi
* prevents absorption
* diarrhea in children (pediatrics)
34
E. coli:
EHEC
* 0157:H7
* dysentery
* Does not ferment sorbitol
* produces shiga like toxin that causes hemolytic-uremic syndrome ( anemia, thrombocytopenia, acute renal failure)
* microthrombi form on endothelium damaged by toxin--\> mechanical hemolysis (schistocytes formed)--\> decreased renal blood flow
* microthrombi consume platelets leading to thrombocytopenia
35
Klebsiella
* Gram negative, rods, lactose fermenter (fast)
* intestinal flora that causes lobar pneumonia in alcoholics and diabetics when **a**spirated
* very mucoid colonies caused by abundant polsaccharide capsules
* red "current jelly" sputum
* also a cause of nosocomial UTIs
* 4 As
* aspiration pneumonia
* abscesses in lung and liver
* Alcoholics
* diAbetics
36
Salmonella
* Gram negative, rod, lactose non-fermenter, oxidase negative
* Have flagella ( salmon swim)
* disseminated hematogenously
* have many animal reservoirs
* produce hydrogen sulfide
* antibiotics may prolong fecal excretion of organisms
* invades intestinal mucosa and causes a monocytic response
* cause bloody diarrhea
* does not ferment lactose
Salmonella typhi
* causes typhoid fever
* found only in humans
* rose spots on the abdomen, fever, headache, diarrhea
* can remain in gallbadder and cause a carrier state
37
Shigella
* Gram negative, Rods, lactose non-fermenter, oxidase negative
* no flagella
* cell to cell transmission ( no hematogenous spread)
* humans and primates are only reservoirs
* does not produce hydrogen sulfide
* antibiotics shorten duration of fecal excretion of organisms
* invades intestinal mucosa and causes PMN infiltration
* often causes bloody diarrhea
* does not ferment lactose
*
38
Campylobacter jejuni
* Gram negative, oxidase positive, comma shaped, grows at 42C
* major cause of bloody diarrhea ( esp children)
* Fecal-oral transmission through foods (poultry, meat, unpasturized milk
* common antecedent to Cuillain-Barre syndrome and reactive arthritis
39
Vibrio cholerae
* Gram negative, oxidase positive, comma shaped, grows in alkaline media
* profuse rice-water diarrhea via enterotoxin that permanently activates Gs ( incr. cAMP)
* Endemic to developing countries
* prompt oral rehydration is necessary
40
Yersinia enterocolitica
* usually transmitted from pet feces (puppies), contaminated milk or pork
* causes mesenteric adenitis that can mimic Crohns disease or appendicitis
41
Helicobacter pylori
* Gram negative, oxidase positive, comma shaped
* produces urease
* causes gastritis and peptic ulcer disease (duodenal)
* risk factor for peptic ulcer, gastic adenocarcinoma and lymphoma
* catase, oxidiase and urease positive
* urea breath test or fecal antigen test for diagnosis
* Tx: triple therapy
* proton pump inhibitor
* clarithromycin
* amoxicillin or metronidazole
42
Spirochete
spiral shaped bacteria with axia filaments
* **B**orrelia ( big, visualized using aniline dye) in light microscopy
* **L**eptospira
* **T**reponema ( dark field microscopy)
43
Leptospira interrogans
* spirochete
* found in water contaminated with animal urine
* causes leptospirosis (flu-like symptoms, jaundice, photophobia with conjunctival suffusion (erythema w/o exudate)
* prevalent among surfers and in tropics
Weil disease
* icterohemorrhagic leptospirosis
* severe form of jaundice and azotemia from liver and kidney dysfunction, fever, hemorrhage, and anemia
44
Borrelia burgdorferi
* Spirochetes
* transmitted by tick Ixodes
* natural reservoir in mouse
* common in northeast US
* Early Symptoms
* erythema chronicum migrans
* flu like symptoms
* +/- facial nerve palsy
* Later symptoms
* monoarthritis (large joints)
* migratory polyarthritis
* cardiac (AV nodal black)
* neurologic (encephalopathy, facial nerve palsy, polyneuropathy)
* Tx: doxycycline, ceftriaxone
45
Treponema pallidum
* Spirochete
* Primary Syphilis:
* localized disease presenting with painless chancre
* serologic testing: VDRL/RPR (non-specific)
* Confirm: FTA-ABS
* Secondary Syphilis:
* Disseminated disease with constitutional symptom, maculopapular rash (palms and soles), condylomata lata
* confirm with dark field microscopy
* Serologic testing: VDRL/RPR (non-specific), confirm diagnosis with specific test ( FTA-ABS)
* systemic
* Latent syphilis (+ serology w/o symptoms) follows
* Tertiary Syphillis
* Gummas ( chronic granulomas), aortitis (vasa vasorum destruction), neurosyphilis (tabes dorsalis)
* Argyll Robertson pupil
* signs: broad based ataxia, + Romberg, Charcot joint, stroke without HTN
* test spinal fluid with VDRL or RPR
* Congenital syphilis
* saber shins, saddle nose, CN VIII deafness, Hutchinson teeth, mulberry molars
* Prevention: treat mother early in pregnancy
46
47
Zoonotic bacteria:
Anaplasmosis
Ixodes ticks
| (live on deer and mice)
48
Zoonotic bacteria:
Bartonella
Cat scratch disease, bacillary angiomatosis
Cat scratch
49
Zoonotic bacteria:
Borrelia Burgdorferi
Lyme Disease
Ixodes ticks
(live on deer and mice)
50
Zoonotic bacteria:
Borrelia recurrentis
Relapsing fever
Louse
recurrent due to variable surface antigens
51
Zoonotic bacteria:
Brucella
Brucellosis/ undulant fever
Unpasteurized dairy
52
Zoonotic bacteria:
Campylobacter
* Bloody diarrhea
* puppies, livestock ( fecal-oral) ingestion of undercook meat
53
Zoonotic bacteria:
Chlamydophila psittaci
* Psittacosis
* parrots, other birds
54
Zoonotic bacteria:
Coxiella burnetiii
* Q fever
* aerosols of cattle/sheep amniotic fluid
55
Zoonotic bacteria:
Ehrilichia chaffeensis
Ehrlichinosis
* Lone star ticks
56
Zoonotic bacteria:
Francisella tularensis
* Tularemia
* Ticks, rabbits and deer fly
57
Zoonotic bacteria:
Leptospira
* Leptospirosis
* Animal urine
58
Zoonotic bacteria:
Mycobacterum leprae
* Leprosy
* Humans with lepromatous leprosy
* armadillo
59
Zoonotic bacteria:
Pasteurella multocida
* Cellulitis, osteomyelitis
* animal bite, cats, dogs
60
Zoonotic bacteria:
Rickettsia prowazekii
* Epidemic typhus
* Louse
61
Zoonotic bacteria:
Rickettsia rickettsii
* Rocky Mountain spotted fever
* Dermacentor ticks
62
Zoonotic bacteria:
Rickettsia typhi
* Endemic typhus
* Fleas
63
Zoonotic bacteria:
Yersnia pestis
* Plague
* Fleas (rats and prairie dog are reservoirs)
64
Gardnerella vaginalis
* pleomorphic, gram-variable rod that is involved in vaginosis
* presents as a gray vaginal discharge with a fishy smell
* non-painful
* associated with sexual activity, but not sexually transmitted
* Bacterial vaginosis is also characterized by overgrowth of certain anaerobic bacteria in vagina
* Clue cells: vaginal epithelial cells covered with Garnerella bacteria
* Tx: metronidazole or clindamycin
65
Rickettsia rickettsii
* Rocky mountain spotted fever
* vector is a tick
* South Atlantic states (North Carolina)
* Rash: starts at wrist and ankle and spreads to trunk, palms, soles
* Obligate intracellular organisms that need coA and NAD+ because they can't synthesize ATP
Triad: headache, fever, rash (vasculitis)
66
Richettsii typhi
* endemic (fleas): Typhus
* rash starts centrally and spread out sparring palms and soles
\* **R**ickettsii on the w**R**ists, **T**yphus on the **T**runk\*
67
Ehrilichiosis
* Erhlichia
* vector is a tick
* monocytes with morulae (berry like inclusions) in cytoplasm
68
Anaplasmosis
* Anaplasma
* vector is a tick
* Granulocytes with morulae in cytoplasm
69
Coxiella burnetii
Q fever
* No arthropod vector
* tick feces and cattle placenta release spores that are inhaled as aerosols
* presents as pneumonia
* no rash, no vector and causative organism can survive outside of its endospore form
70
Chlamydiae
* can't make their own ATP
* obligate intracellular organisms that cause mucosal infections
* 2 forms
* Elementary body (small dense)- infectious and enters cells via endocytosis
* Reticulate body replicates in cell by fission
* Chlamydia trachomatis
* reactive arthritis: Reiter syndrome
* follicular conjunctivitis
* nongonococcal urethritis
* PID
* C. pneumoniae and C. psittaci: atypical pneumonia (transmitted by aerosol)
* Lab diagnosis: cytoplasmic inclusions seen on Giemsa or fluorescent antibody smear
* Tx: azithromycin or doxycycline
71
Chlamydia Trachomatis
* Types A, B, C
* Chronic infection
* cause blindness due to follicular conjunctivitis in Africa
* Types D-K
* Urethritis/PID
* ectopic pregnancy
* neonatal pneumonia (staccato cough)
* neonatal conjunctivitis
* Types L1, L2, L3
* Lymphogranuloma venereum
* small, painless ulcers on genitals --\> swollen, painful inguinal lymph node that ulcerate (buboes)
* Tx: doxycycline
72
Mycoplasma pneumoniae
Classica cause of atypical "walking" pneumonia
* No cell wall, not seen on gram stain
* bacterial membrane contains sterols for stability
* frequent outbreaks in military recruits and prisons
* insidious onset, headache, nonproductive cough, patchy or diffuse interstital infiltrate
* High titer of cold agglutinins (igM) which can agglutinate or lyse RBCs
* Grown on Eaton agar
* Tx: macrolide, doxycyline or fluoroquinolone (penicillin inffective)
