Anaerobes

anaerobes will not grow in the presence of ____.

oxygen

most clinically significant anaerobes are part of our ____ but infections occur when they gain access to sterile body sites as a result to disruption of anatomic barrier.

normal flora

some pathogenic anaerobes are environmental (soil) and are not considered normal flora. list 2 examples.

clostridium botulinum; clostridium tetani

suspect ____ if:

• polymicrobial results on gram stain-culture

• gas in pus/infected tissues

• foul odor (from gas) of pus/infected tissue

• necrotic tissue

• site of infection are where normal flora can be found (e.g., gut)

anaerobes

incidence of ____ of all genera as normal flora are in the upper respiratory tract and intestines.

anaerobes

which genus is normal flora of the skin?

cutibacterium

the following are acceptable for anaerobic ____ (source) cultures:

• thoracentesis (pleural) fluid

• transtracheal aspirate

• bronchial washings obtained with double lumen plugged catheter

• percutaneous (direct) lung aspirate/biopsy

respiratory

the following are acceptable for anaerobic ____ (source) cultures:

• bile

• peritoneal (ascites) fluid

abdominal

the following are acceptable for anaerobic ____ (source) cultures:

• suprapubic bladder aspirate

• uterine contents (use protected swab)

• biopsy of endometrial tissue (with curette)

genito/urinary

the following are acceptable for anaerobic ____ (source) cultures:

• tissue obtained at biopsy/autopsy

• material aspirated from abscesses

• decubitus ulcer (if collected from base of lesion post debridement of surface debris)

wounds

the following are acceptable for anaerobic ____ (source) cultures:

• blood

• bone marrow

circulatory

fluids from normally sterile sites such as joint, CSF, etc. are unacceptable for anaerobic culture. true or false?

false

which anaerobic media is described below:

• anaerobic blood agar

• enriched

• for general growth of all anaerobes

CDC

which anaerobic media is described below:

• selective and differential

• used to culture and ID bacteroides fragilis

bacteroides bile esculin (BBE) agar

which anaerobic media is described below:

• enriched and selective

• used to grow most anaerobes

• inhibits facultative anaerobic GNR (e.g., enterobacteriaceae)

phenylethyl alcohol (PEA) agar

which anaerobic media is described below:

• enriched and selective

• for isolation of slow growing anaerobes (e.g., prevotella, bacteroides)

• laked blood enhances pigment

kanamycin-vancomycin laked sheep blood (KVLB) blood

which anaerobic media is described below:

• selective

• inhibits gram negatives

• used to grow most gram positive

• anaerobes/facultative anaerobes

columbia-colistin-naladixic agar with 5% sheep blood

which anaerobic media is described below:

• differential

• used to detect clostridium enzymes:

  • lipase positive: blue-green sheen (mother of pearl) on top agar surface

  • lecithinase positive: opaque zone (fats)

egg yolk agar

which anaerobic media is described below:

• enrichment differential: when resazurin added

  • resazurin: pink presence of O2, colorless when reduced

• enhance growth of anaerobes

broths with reducing agents (thioglycolate, cooked/chopped meat)

for anaerobic jars, signs that it is working properly are that the methylene blue indicator will turn from blue to ____ as well as produce heat within a few minutes (top warm).

white

what bacteria is responsible for most anaerobic infections?

bacteroides fragilis

bacteroides fragilis is major normal flora of the ____.

colon

infections by bacteroides fragilis are often mixed with other anaerobes and facultative anaerobes. true or false?

true

which bacteria usually causes infection after gaining entry into normal sterile body sites:

• usually following surgery, trauma, disease

• foul odor is common

• “below the diaphragm” infections, mostly

bacteroides fragilis

what bacteria contains the following virulence factors:

• capsules, endotoxin, succinic acid (inhibits phagocytosis), various enzymes that mediate tissue damage

• most infections still require some breach of mucosal integrity to allow organisms to gain access to deeper tissue

bacteroides fragilis

bacteroides fragilis is resistant to all of the following EXCEPT:

• kanamycin

• vancomycin

• colistin

• penicillin

• rifampin

rifampin

which bacteria has the following characteristics:

• pleomorphic GNR with rounded ends and safety pin appearance (bipolar staining)

• grows on BBE

  • >1mm in diameter, brown → black, circular, raised, surrounded by a grey zone (esculin hydrolysis)

    • some strains hydrolyze bile esculin

bacteroides fragilis

what bacteria is associated with the following information:

• GNR

• normal flora of the upper respiratory and GI tracts

• asacchrolytic or weak fermenters; relatively bioinert

fusobacterium

which species of fusobacterium is associated with the following information:

• causes severe pulmonary infections

• more common

• gram stain: slender with pointy ends

• 3 colony types:

  • bread crumb like, white

  • speckled

  • smooth

• greening of agar with air, usually non-hemolytic, fluoresces chartreuse

fusobacterium nucleatum

which species of fusobacterium is associated with the following information:

• lung and liver abscesses, arthritis

• pediatric/adolescent pharyngitis

  • can progress to Lemierre syndrome (rare): formation of infected blood clots that can then circulate in blood, spreading infection

• causes more serious infections

• colony:

  • circular, ridged surface, translucent → opaque, green with exposure to air, some strains beta-hemolytic (small zone), fluoresces chartreuse

fusobacterium necrophorum

what bacteria is associated with the following information:

• pigmented, saccharolytic GNR

  • ANA blood agar: dark center with grey → brown edges; circular, convex, smooth, shiny

    • young colonies appear tan

    • older colonies brown → black (may take weeks to see this pigment)

  • fluoresces brick red

prevotella melaninogenica

what bacteria is associated with the following information:

• normal flora of the oropharynx, nose, GI and urogenital tracts

• can hydrolyze esculin (black on LKV)

• inhibited by 20% bile

• vitamin K in media enhances its growth

• in media is enriching for this organism

prevotella melaninogenica

what bacteria is associated with the following information:

• GNR

• asaccharolytic or weak fermenters

• normal flora of oropharynx, nose, and GI and urogenital tracts

• will not grow on KVLB agar (inhibited by vancomycin and bile)

• colony (ANA BA): dark brown-black

• brick red fluorescence under UV light

porphyromonas

most porphyromonas species display brick red fluorescence. which species does not (an exception)?

porphyromonas gingivalis

what bacteria is associated with the following:

• small, gram-negative cocci

  • can be clusters, pairs, short chains

• colony

  • small, almost transparent; greyish white, smooth, buttery; may show red fluorescence under UV light

veillonella

what bacterial genus is associated with the following:

• some species are normal flora of the GI tract (humans and animals)

• some species environmental (soil, water, dust)

• large GPR

  • may be coccoid or filamentous

• produce a variety of exotoxins

• spore forming

clostridium

which of the following choices is best described below:

• spores +

• anaerobic growth optimal

• catalase -

a. clostridia

b. bacillus

c. lactobacillus

clostridia

which of the following choices is best described below:

• spores +

• aerobic growth optimal

• catalase + (usually)

a. clostridia

b. bacillus

c. lactobacillus

bacillus

which of the following choices is best described below:

• never form spores

a. clostridia

b. bacillus

c. lactobacillus

lactobacillus

some clostridia rarely produce spore and may not survive the ethanol test. provide a species examples.

clostridium perfringes

what bacteria is associated with the following information:

• obligate anaerobe

• found in soil

• cause of tetanus

  • usually diagnosed clinically due to characteristic symptoms; generally not cultured

• colonies

  • swarming appearance

• GPR

  • “drumstick” or “tennis racket” (due to terminal spores)

clostridium tetani

for tetanus infections, bacteria must enter the wound deep enough so that is can live aerobically. true or false?

false

symptoms of tetanus are caused by a neurotoxin known as _____.

tetanospasmin

what condition involves blocking the relaxation pathway of muscles so that muscles continually spasm and contract?

tetanus

what term refers to muscles in the neck and jaw being affected early in the disease and prevents the mouth from opening caused by tetanus?

lockjaw

tetanus is not spread person to person. true or false?

true

tetanus is vaccine preventable (TDaP, Tdap, DT, Td (toxoid); however, about 1 million cases occur worldwide with about half being ____ in developing countries.

newborns

what bacteria causes botulism?

clostridium botulinum

what refers to a neurotoxin that binds to the synapse of nerve fibers; blocks nerve impulses (opposite of toxin C. tetani)?

botulism toxin

what toxin will result in acute (flaccid/limp) paralysis and death?

botulism toxin

what bacteria is associated with the following information:

• obligate anaerobe

• found in soil and dust and freshwater sediment

• can form spores when needed

clostridium botulinum

what bacteria on a gram stain depict oval/subterminal spores and resemble tennis rackets?

clostridium botulinum

which form of botulism is described below:

• ingest food with botulism toxin

• 15% cases in US (home-canning a risk)

foodborne

which form of botulism is described below:

• 20% cases in US

• cases associated with injection drug use; black tar heroin especially in CA; sharing needles

wound

which form of botulism is described below:

• consume spores: bacteria germinate in intestine and produce toxin

• 65% of cases in US (most common)

• can be rapidly fatal

infant

which form of botulism is described below:

• very rare

• same route as infant botulism

adult intestinal toxemia

which form of botulism is described below:

• accidental overdose of botulinum toxin

iatrogenic

botulism is not spread person to person. true or false?

true

what condition is associated with the following symptoms:

• blurred vision, slurred speech, difficulty swallowing, dry mouth, muscle weakness → flaccid paralysis → respiratory failure → death

botulism

which form of botulism is treated with anti-toxin (available through CDPH)?

infant

which form of botulism is treated with enemas or induced vomiting to try to remove contaminated food in the gut?

foodborne

which form of botulism is treated with surgical removal of toxin producing bacteria and followed up with antibiotics?

wound

what bacteria is found in the human intestinal tract, soil, and water and causes gas gangrene and food poisoning?

clostridium perfringes

what condition by clostridium perfringes is associated with the following:

• improperly stored/cook meat products

• due to exotoxin; not passed person to person

• antibiotic treatment is not recommended

food poisoning

what condition by clostridium perfringes is associated with the following:

• carbohydrate fermentation within a wound

• hydrogen gases are formed via fermentation

gas gangrene

what condition by clostridium perfringes is associated with the following:

• diabetic patient with poor circulation/vasculature (especially to feet) → not enough blood reach the tissue → tissue does not receive enough oxygen → ischemia

  • low oxygen environment → anaerobes

  • tissues that do not receive enough blood/oxygen die

gas gangrene

in addition to gas production through fermentation, what bacteria also produces exotoxins and enzymes to further interfere with blood supply → allow bacteria to spread?

clostridium perfringes

what bacteria is described below:

• gram stain: box car shaped rods

• colony (ANA BAP): double zone beta hemolysis

• reverse CAMP positive

• lecithinase positive

  • opaque on yolk agar

  • nagler test positive

    • one side anti-alpha toxin: no opaqueness around colony streak

    • one side not anti-alpha toxin: characteristic opaque around colony (lecithinase inhibited)

clostridium perfringes

for the reverse CAMP test, streptococcus agalactiae should be streaked with clostridium perfringes in a position where it will be _____ to the strep.

perpendicular

the CAMP factor made by streptococcus agalactiae interacts with which toxin of clostridium perfringes in the reverse CAMP test to create a synergistic hemolysis reaction?

alpha toxin

what bacteria refers to a toxin producing anaerobic gram positive rod?

clostridium difficile

what toxingenic strain of clostridium difficile refers to an enterotoxin?

toxin A

what toxingenic strain of clostridium difficile refers to an cytotoxin?

toxin B

what toxingenic strain of clostridium difficile is more potent and more likely to be associated wit severe and recurrent disease?

toxin B

what bacteria is associated with the following information:

• fecal-oral transmission: requires toxin-producing strain to enter your gut (infective dose can be as low as 10 spores)

• some people are colonized already and are asymptomatic

clostridium difficile

what bacteria is associated with antibiotic use (broad spectrum mostly) where most of our normal flora can be wiped out and may lead to colitis?

clostridium difficile

what bacteria is associated with the following complications:

• dehydration

• kidney failure

  • result of rapid dehydration

• toxin megacolon

  • intestine cannot expel gas and stool → becomes distended and ruptures → gut bugs in abdominal cavity

  • requires emergency surgery and can be fatal

• bowel perforation

  • due to extensive injury to intestine → peritonitis

• death

clostridium difficile

which bacteria can be treated with the following methods:

• fluid replacement

• more antibiotics:

  • most common: flagyl (metronidazole), vancomycin, fidaxomicin

• probiotics

  • replace normal gut flora

• surgery

  • removed diseased portion of intestine

• fecal microbiota transplant (FMT) / stool transplant

clostridium difficile

for the identification of clostridium difficile, EIA methods are fast, but ____ can be very low (miss true positives)?

sensitivity

for the identification of clostridium difficile, EIA methods test for both toxins A/B as well as the enzyme ____.

glutamate dehydrogenase (GDH)

for the identification of clostridium difficile, EIA methods do not differentiate between toxigenic and nontoxigenic strains. true or false?

true

NAAT/PCR methods for the identification of clostridium difficile have a very good _____ (true positives detected).

sensitivity

NAAT/PCR methods for clostridium difficile cannot pick up asymptomatic carriers. true or false?

false

formed stools are generally rejected for clostridium difficile as the _____ degrades at room temperature and may be undetectable within 2 hours (must be tested promptly or refrigerated).

toxin

on cycloserine-cefoxitin-fructose agar (CCFA) for clostridium difficile, colonies are ____ and have a ground glass appearance.

yellow

what media for clostridium difficile has the following characteristics:

• yellow, ground glass colonies

• smells like horse manure

• fluoresces chartreuse (yellow green) when exposed to UV light

CCFA

culture followed by strain testing for the toxin is considered to be a gold standard for the testing of which bacteria?

clostridium difficile

for clostridium difficile, toxin genes do not degrade at room temperature. true or false?

false

what bacteria is also referred to as propionibacterium?

cutibacterium

what bacteria is best described below:

• gram positive, pleomorphic diphtheroid-like rod

  • club-shaped palisades

  • “anaerobic diphtheroids”

  • non-spore forming

• normal flora of skin, mouth, GI tract

  • common contaminant (most common in blood cultures)

  • associated with inflammatory process in acne (“acne vulgaris”)

• opportunistic pathogen

  • post-op surgical site infections, endocarditis, device-related infections

cutibacterium

which species of cutibacterium is the 3rd most common cause of shunt infections (CNS infection)?

cutibacterium acnes

cutibacterium is catalase and indole ____.

positive

what bacteria is best associated with the following information:

• gram variable, small, thin, curved rods

  • non-spore forming

  • motile; catalase positive; indole negative

  • vancomycin susceptible

• organisms are found in the vagina

  • associated with bacterial vaginosis (BV), PID, abdominal infections

mobiluncus

what bacteria is best associated with the following information:

• gram positive diphtheroid/irregular

  • rods terminate in clubs or thick, bifurcated (forked) ends

  • “dog bones”

• mostly nonpathogenic normal oral and intestinal flora

  • most commonly found in mixed cultures of pelvis or abdomen

• used in yogurts/probiotics

bidifobacterium

what bacteria is best associated with the following information:

• mostly nonpathogenic normal oral and intestinal flora

  • have been implicated in abdominal infections and bacteremia

• gram positive pleomorphic rods-coccobacilli

  • pairs or short chains

eubacterium

which species of eubacterium is best described below:

• seagull shape, similar to campylobacter

  • found in oral cavity; periodontal disease

eubacterium alactolyticum

which species of eubacterium is best described below:

• beading, filaments, branching, similar to actinomyces

  • found in oral cavity; periodontal disease

eubacterium nodatum

which species of eubacterium is best described below:

• now known as eggerthella lenta

• small, straight rod with rounded ends

  • found in GI tract: colon infections, liver, anal abscesses, bacteremia

eubacterium lentum

what bacteria is described below:

• normal flora of mouth, upper respiratory tract, intestine

• catalase positive

• produces olive-green colonies that become black

• most often found with other anaerobic and facultative anaerobic bacteria

  • cutaneous, respiratory, oral, female pelvic infections

peptococcus

which species of peptostreptococcus is associated with the following:

• gram positive large coccobacillus, often in chains

• colony: medium, grey white, opaque,

  • sweet fetid odor

  • usually larger than other anaerobic cocci

  • inhibited by SPS

peptostreptococcus anaerobius