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Microbiology > Exam 3 > Flashcards

Exam 3 Flashcards

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1
Q

Anaerobes

A
  • infections are close to mucosal surface
  • foul odor
  • produce large quantities of gas
  • black color or brick-red fluorescence
  • anaerobic infections are usually polymicrobial
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2
Q

G+ spore-forming rods

A

Clostridium genus

catalase negative (unlike bacillus)

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3
Q

C. perfringens

A
  • boxcar shaped
  • double zone of beta hemolysis
  • Type A: ingestion of toxin that causes diarrhea and cramps
  • Type C: bloody diarrhea with necrotic inflammation of the small intestine (can be fatal)
  • can cause myonecrosis aka gas gangrene
  • most common isolate in blood cultures
  • Egg yolk agar: opaque zone around colony (lecithinase)
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4
Q

C. botulinum

A
  • from canned foods
  • causes flaccid paralysis
  • botulism
  • ingestion of preformed botulin toxin, babies eating honey, wounds
  • Toxin A is used for Botox
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5
Q

C. tetani

A
  • heavy swarming with terminal spores
  • neurtotoxin inhibits nuerotransmitters
  • tetanus
  • spastic/rigid paralysis
  • TDaP vaccine
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6
Q

C. difficile

A
  • most common isolate in antibiotic-associated diarrhea
  • can cause colitis
  • develops because normal flora is destroyed by antimicrobials
  • nosocomial
  • test for toxin production
  • CCFA is selective: yellow round glass colonies
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7
Q

G+ non-spore forming rods

A

Actinomyces
Bifidobacterium
Propionibacterium (P. acnes is a frequent contaminent in blood cultures)

-all three can cause actinomycosis which is when sinus tracts erupt to the surface and drain pus that contains sulfur granules

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8
Q

G- anaerobic bacilli

A

Bacteroides (most common)
Prevotella
Porphyromonas
Fusobacterium

G- anaerobic cocci (veillonella)

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9
Q

Bacteroides fragilis

A
  • # 1 NF bacteria in human colon
  • # 1 causative agent in peritonitis and intra-abdominal abcesses

B. ureolyticus may pit agar

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10
Q

Prevotella melaninogneica

A
  • # 1 bacteria of gingiva (also in vagina)

- turns to a brown-black color over 2-3 weeks

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11
Q

Porphyromonas

A
  • normal flora of the mouth & GU tract

- head/neck infections

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12
Q

Fusobacterium

A
  • oral flora, also in GI, GU, and URT
  • sores, foot ulcers, etc
  • Lemierre’s disease- can cause clots in jugular vein
  • both species fluoresces chartreuse
  • resistant to vancomycin
  • F. nucleatum- long/thin with pointed ends. lipase negative.
  • F. necrophorum- has rounded ends. lipase positive.
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13
Q

Anaerobic cocci

A

Peptostreptococcus

  • brain abscesses, meningitis, pneumonia, and gingivitis
  • SPS test: Peptostreptococcus is sensitive & Peptoniphilus is resistant
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14
Q

Anaerobic testing

A
  • best cultures are tissue biopsy or needle aspiration
  • rapid processing due to drying out and exposure to O2
  • PRAS media to isolate since most anaerobic infections are polymicrobial
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15
Q

Anaerobic chambers

A
  • H2 (5-10%)
  • CO2 (5-10%)
  • N2 (80-90%)
  • palladium coated alumina pellets remove any residual O2
  • dessicant absorbs excess water
  • indicator: blue or pink when O2 present
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16
Q

KVLB agar

A

eliminates most Gram negative via kanamycin & most Gram positive via vanco

Kanamycin: sensitivity indicated Bacteroides (except B. fragilis) or Fuso & Veillonella

Vancomycin: sensitivity indicates G+ bacillus or Porphyromonas

Prevotella & B. fragillis are resistant to V & K (black color)

Colistin disc (not on agar): sensitivity indicates same as kanamycin plus Prevotella

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17
Q

BBE agar

A
  • bile

- B. fragilis group

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18
Q

Fluorescence

A
  • Porphyromonas & Prevotella: brick-red
  • Fusobacterium & C. dif: chartreuse
  • Veillonella: red
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19
Q

Spot indole test

A
  • blue-green = positive

- P. acnes is the only one

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20
Q

Spirochetes

A
  • helical shaped
  • unicellular motile bacteria
  • usually treat with doxy or tetracycline
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21
Q

Leptospira

A
  • tightly coiled
  • L. interrogans causes Leptospirosis (Swineherd’s disease)
  • severe systematic disease = Weil’s disease
  • zoonotic disease, excreted in urine
  • Fletcher’s agar
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22
Q

Borrelia

A
  • loosely coiled
  • anthropod borne (Ixodes tick)
  • Kelly medium
  • microaerophillic
  • requires fatty acids for growth
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23
Q

B. recurrentis

A
  • relapsing fever
  • can be seen in PB
  • death of spirochetes can cause sudden endotoxin release (Jarisch-Herxheimer rxn = flu-like symptoms)
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24
Q

B. burgdorferi

A
  • Lyme’s disease
  • Stage 1: bulls-eye rash
  • Stage 2: arthritis, meningitis, lesions
  • Stage 3: chronic lesions, neurological symptoms, permanent disability
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25
Q

Treponema pallidum

A
  • Syphillis

- can cross placenta (all treponemals can)

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26
Q

T. pallidium: pertenue

A
  • Yaws
  • nonvenereal
  • lesions on face
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27
Q

T. pallidum: endemicum

A
  • Endemic syphillis (bejei)
  • contact with contaminated eating utensils
  • resembles Yaws
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28
Q

T. pallidum: carateum

A
  • Pinta

- ulcerative/papulo lesions that depigment skin

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29
Q

Syphillis

A
  • gay male sex
  • Primary: chancre at infection site (penis or vagina/cervix)
  • contains spirochetes that can be seen in dark field microscopy
  • Secondary: widespread macular rash (syphilitic roseola) on palms/soles of feet and condylomata kata (most gray-white plagues with spirochetes)
  • Latent: pt is asymptomatic but still infectious
  • Tertiary (late): late complications such as CNA issues
  • Congenital- intrauterine that causes facial abnormalities such as Hutchinson’s teeth
30
Q

Chlamydia

A
  • obligate intracellular parasites

- two forms: elementary body (infectious phase) and reticulate body (replicate/non-infectious phase)

31
Q

C. trachomatis

A
  • most common bacterial STD in the US
  • males: urethral discharge, urethritis, conjunctivitis, prostatitis, etc.
  • females: cervicitis, PID, conjunctivitis, discharge, can cause infertility
  • often asymptomatic**
  • other infections: neonatal (Reiter syndrome, passed through birth canal), Lymphogranuloma Venereum (bubo formation, genital/anal papule), Trachoma (blindness..#1 cause of avoidable blindness)
  • humans only reservoir
  • to dx, mucosa scraping (1st morning urine/vaginal swabs are best)
32
Q

C. pneumoniae

A
  • TWAR
  • via respiratory droplets
  • endotoxin
  • life cycle promotes infection
  • survive in macrophages
  • cause recurrent or persistant infections
33
Q

C. psittaci

A
  • bird chlamydia
  • parrot fever
  • pneumonia in humans
  • via respiratory droplets
34
Q

Rickettsiae

A
  • obligate intracellular bacteria
  • transmission through ticks
  • Spotted fever & Typhus group
35
Q

Spotted Fever Group

A
  • R. rickettsii: Rocky Mt Spotted Fever
  • ticks: D. variabilis & D. andersoni
  • flu-like symptoms with rash on ankles/wrist- NOT FACE
  • R. konorii: Boutonneuse Fever aka Mediterranean spotted fever
  • reservoirs are ticks and dogs
  • rash on palms/soles of feet/body/face
  • Taches noires: black spots at primary site of infection
36
Q

Typhus group

A
  • R. typhi: endemic typhus aka murine typhus
  • oriental rat/cat flea
  • flea poops on skin and scratching infects the bite
  • R. prowazekii: epidemic louse-borne tyhpus aka Brill-Zinsser disease
  • human louse/squirrel flea/louse
  • rash all over-including face
37
Q

Rickettsialpox

A
  • R. akari
  • reservoir is house mouse
  • vector is mouse mite
  • papules form at bite and progresses to a pustule
  • rash everywhere except for palms/soles
38
Q

Scrub Typhus

A
  • causative agent is Orientia tsutsugamushi
  • vector- chigger
  • reservoir is rat
  • tache noire at site of inoculation
  • rash IS NOT on face, soles, palms
39
Q

Anaplasmataceae family

A
  • Ehrlichia: dogs infected with brown dog ticks
  • asymptomatic in humans
  • can form morulae in cells (in WBC)
  • Lone star tick
40
Q

Coxiella

A
  • C. burnetti
  • Query fever
  • livestock are reservoirs
  • bioterrorism agent
41
Q

Mycoplasma

A
  • smallest free-living organisms in nature
  • do not possess cell walls so cannot Gram stain and extremely sensitive to drying
  • resistant to cell wall antibiotics (PCN)
  • slow growing, fastidious (need cholesterol & fatty acids)
  • dacron swab or freeze @ -70 degrees C
  • spread via close contact (aerosols)
  • look like fried eggs on agar
42
Q

M. pneumoniae

A

bronchitis/pharyngitis

  • walking pneumonia (atypical pneumonia- usually asymptomatic)
  • adheres to oropharynx cells
  • isolation always indicates pathogenicity
  • typically not cultured- uses serology
  • rx = erythromycin or Z-pak
43
Q

M. hominis

A
  • urogenital
  • requires arginine
  • normal flora-opportunistic pathogen
  • rx = clindamycin
44
Q

ureaplasma

A
  • urogenital infections
  • meningitis of newborns
  • urethritis in men
  • requires urea
  • rx = erythromycin
45
Q

ID of Mycoplasma

A
  • on A8 agar: look for fried egg appearance for M. hominis & irregular shaped colonies for ureaplasma
  • in liquid media- look for pH change which will turn pink
46
Q

Mycobacteria

A
  • non-motile
  • non-spore forming
  • cell wall has high lipid content (mycolic acid) so its resistant to Gram stain
  • aerobic
  • requires complex media
  • divided into two groups: M. tb complex (both are catalase neg and inhibited by NAP) & nonTb mycobacteria (NTMs) and then M. leprae is by itself
47
Q

M. bovis

A
  • MTB complex
  • primary in cattle
  • transmission via ingestion of contaminated milk or airborne
  • inhibited by T2H and pyrazinamidase (differentiate from M. TB)
  • niacin neg
  • doesnt reduce nitrate
48
Q

M. tuberculosis

A
  • MTB complex
  • primary TB
  • transmitted via airborne droplet
  • bacteria gets phagocytsed and can still multiply (+PPD test)
  • reactivation can occur in advanced age, immunocompromised, and malnutrition pts (night chills common symptom)
  • slow grower: raised dry rough appearance
  • cord factor
  • optimal growth: 35-37 degrees
  • only non-pigment producer that is positive niacin accumulation and reduces nitrate
  • positive pyrazinamidase
  • converts to nicotinic acid (yellow color)
  • treatment: 9 course regimen of isoniazid & rifampin
49
Q

Miliary tb

A

spread of bacteria from lungs to bloodstream (M. tb)

50
Q

M. avium/M. intracellulare

A
  • most common NTM causing tb in the US
  • pulmonary disease that resembles TB
  • slow growing
  • associated with HIV/AIDS pts
  • growth in T2H media

M. avium subsp. paraTB: Johne’s disease- chronic diarrhea in livestock

51
Q

M. kansasii

A
  • 2nd most common cause of NTM lung disease in US
  • slow grower
  • photochromogenic
  • reduces nitrate**
  • produces pyrazinamidase
52
Q

Photoreactivitiy

A

photochromogens: carotene pigment upon exposure to light
scotochromogens: pale yellow to orange color in dark or light
nonchromogenic: buff of lack of color

53
Q

M. genavense

A
  • AIDS pts

- enteritis, genital, and soft tissue infections

54
Q

M. haemophilum

A
  • immunocompromised pts
  • not pulmonary
  • lymphadenitis and nodules (cutaneous)
55
Q

M. malmoenese

A

chronic pulmonary disease and cervical lymphadenitis

56
Q

M. marinum

A

-cutaneous infections due to contain with salt water or inadequate chlorinated water
aka swimming pool granuloma
-positive pyrazinamidase

57
Q

M. scrofulaceum

A
  • cervical lymphadenitis in children
  • scotochromogen
  • positive urease (differentiates from M. gordonae)
58
Q

M. simulae

A
  • pulmonary disease in pts with preexisting lung conditions
  • parts of Texas
  • photochromogenic and produces niacin
59
Q

M. szulgai

A
  • pulmonary disease similar to TB

- photochromic

60
Q

M. ulcerans

A
  • nodule that develops into ulcers

- nonchromogenic buff colonies

61
Q

M. xenopi

A
  • recovered from hot and cold water temp birds and taps
  • can grow at 42 degrees
  • pulmonary
  • scotochromic
62
Q

M. gordonae

A
  • found in tap water and soil aka tap water bacillus**
  • found in clinical specimens but not pathogen
  • scotochromogen
63
Q

Rapid growing species (more than 7 days)

A
  • M. chelonae: M. abscesses group
  • opportunistic infections
  • cutaneous
  • only rapid grower to be be negative for iron uptake
  • more drug resistance than others in this group
    • 3-day arylsulfatase test and will grow on MAC
  • doesnt reduce nitrate
64
Q

M. leprae

A
  • Hansen’s disease (leprosy)
  • two types
  • tuberculoid-skin lesions and nerve involvement but spontaneous recovery and
  • lepromateous- skin lesions and progressive nerve damange that can lead to deformities and can be fatal
  • person to person transmission
  • armadillo,mouse feet
65
Q

specimen collection

A

early morning respiratory specimen on 3 consecutive days (only 2/3 need to be positive for confirmatory)

66
Q

digestion/decontamination

A
  • digestion: liquefy the sample so the bacteria can absorb nutrients in media
    decontamination: allow the chemical agent to kill non-mycobacterial organisms (mycobacteria survive due to high lipid cellular walls)
  • samples collected aseptically do not require this (CSF, pleural fluid, joint fluid)
  • agents: NAOH & acetyl-cysteine
67
Q

Staining

A

acid fast stain (Ziehl-Neelsen)

  1. carbofuchsin while heating
  2. acid alcohol (decolorized)
  3. methylene blue (counter stain)

blue background with red organism**

kinyoun stain is the same except without heat

68
Q

Medias

A

Lowenstein-Jensen media
American Thoracic Society media
Middlebrook media

all contain malachite green which suppresses the growth of G+ organisms

69
Q

BACTEC system

A

culturing system of mycobacteria

amount of labeled CO2 is detected and interpreted as a growth index

70
Q

MGIT

A

same principle as BACTEC but measures O2 consumption via fluorescence

Microbiology (26 decks)

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