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74 Cards in this Set
- Front
- Back
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Anaerobes Defined |
*obligate won't grow in O2 *some are aerotolerant *lack Catalase & Superoxide dismutase!! (protects them from molecular O2 and free radicals) |
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Sources of Anaerobic Infection |
*clinical isolates originate from endogenous flora *Exogenous may be found in soil, water, or gain entry through ingestion or wound *Nosocomial transmission (C. difficile) *Ingestion of preformed toxins (Botulism) |
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Where anaerobe outnumber aerobes |
*oral cavity *GI tract *urogenital tract *can be in skin but don't outnumber aerobe |
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Factors Predisposing Patients to infection |
*trauma to mucous membranes *human/animal bites *Oral, GI, or UG surgery *exposure of open wounds to soil *vascular stasis *tissue necrosis *respiratory aspiration event |
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Indications of Anaerobic Involvement |
*Proximity of infection to a mucosal surface *Infection persists despite aminoglycoside therapy *presence of foul odor or gas *presence of sulfur granules *distinct morph. charac. in direct smear |
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Appropriate Specimen for anaerobic culture |
*sterile body fluids *needle-aspirated material (abscesses) *surgical specimens (deep tissue, bone) *suprapubic aspirates |
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Inappropriate Spec. for anaerobic culture |
*exudates & other material collected on swab from superficial wounds etc *vaginal, cervical, urethral swabs *respiratory spec. *stool or rectal swab (90% stool is anaerobe) *voided or catheterized urine |
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Specimen transport |
*rapidly, min. air exposure *needle aspirate (expel any air bubbles) *swabs (Use PRAS transport medium) *Tissue (use transport media, or empty sterile container) *Blood (unvented bottle) |
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Specimen Processing |
*Processed ASAP (ideally in anaerobic chamber) *prepare direct smear & inoculate media (SBA/ANA + K 30 ug disk) *add. selective plates can be added if indicated *use direct smear to assess spec. quality |
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Culture Incubation |
*anaerobic chamber *anaerobic jar w/ gas pack (O2 absorbed and CO2 generated, some gas packs req. palladium) *Indicator used to monitor for presence of O2 (methylene blue & resazurin)!!! |
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Id anaerobic isolates |
*examine plates at 24 and 48 hrs *foul odor *colony morph *compare growth to aerobic *subculture (aerotolerance test and ID discs) *fluorescence |
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Media for Anaerobes |
*Brucella blood agar (BRU)--vit. K, hemin *Bacteroides bile esculin (BBE) *Kanamycin-vancomycin laked blood *phenylethyl alcohol (PEA) *Egg yoke agar (EYA) *anaerobic broth (thioglycollate) |
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EYA Media Rxn!! |
*Lecithinase +: rxn occurs w/in agar *Lipase +: Rxn occurs on surface of agar |
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Anaerobic Broth Media |
*thioglycollate w/ vit. K and hemin *Chopped meat glucose (PRAS) *Cooked meat (enhance spore formation of clostridia) *not used routinely unless spec. is tissue or sterile body fluid |
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LKV |
*selective anaerobic media *used for selecting most GN anaerobes |
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Bacteroides Bile Esculin (BBE) |
*Selective media *useful for recovery of GN anaerobes that grow in presence of 20% bile *good for ID B. fragilis group |
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Special Potency antimicrobial discs !!! |
*Vancomycin (5 ug) *Kanamycin (1000 ug) *Colistin (10 ug) *bile |
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ID methods |
*special potency antimicrobial discs *nitrate *spot tests (Catalase, indole, motility) |
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Frequency of Isolation |
*Bacteroides is the most common anaerobe isolate |
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anaerobic GN Bacilli |
*Bacteroides spp *Prevotella spp *Porphyromonas *Fusobacterium |
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Bacteroides fragilis group Clin |
*infection from neck down |
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B. fragilis GS morph |
*pale staining short GNR w/ pleomorphism (like Haemophilius) |
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B. fragilis on SBA |
*white/grey, circular, convex,translucent to, nonhemolytic *foul odor |
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B. fragilis on BBE |
*some turn black due to esculin hydrolysis (growth at 48 hrs) |
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B. fragilis Group ID!! |
*indole/catalase V *Nitrate - *ID discs (K, V, CL resistant) |
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Bacteroides (camplyobacter) ureolyticus Clin sig |
*pulmonary *head/neck *intra-abdominal *urogenital *bone *soft tissue infections
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B. ureolyticus GS |
*small, slim, GNRs, variable length |
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B. ureolyticus SBA/ANA |
*pinpoint, convex, MAY PIT AGAR *No growth on BBE *urease + |
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B. ureolyticus ID |
*indole - *most cat - *nitrate + *ID Disc (K, CL, Bile sensitive; V resistant) *urease + |
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Prevotella & Porphyromonas spp Clin Sig |
*normal oral flora *infections usually involve head and neck *also lower resp. and urogenital tract |
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Prevotella & Porphyromonas GS |
*similar to bacteroides |
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Prevotella & Porphyromonas SBA |
*May produce protoporphyrin (gives colonies brown/black color after several days) *MAY FLUORESCE BRICK RED (helps differentiate btwn bacteroides which does not fluoresce) |
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Prevotella & Porphyromonas Similarities |
*tiny coccobacilli *no growth on BBE *may be brown/black *fluoresce brick red |
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prevotella & porphyromonas differences |
*Pre-V res; Por-V sensi *Pre grows on LKV *Por-indole + (only prevotella intermedia is +) |
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Fusobacterium nucleatum Clin sig |
*frequently involved in pleuropulmonary infections following an aspiration event *most common of the fusobacterium *norm flora of GI, geniturinary, Upper resp. |
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Fusobacterium nucleatum GS |
*Distinctly Fusiform |
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F. nucleatum colony morph |
*SBA: crumb like/speckled or smooth *No growth on BBE *Fluoresces Green! |
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F. nucleatum ID !! |
*Ind + *Cat/Nit - *ID Disc K sens V res CL sens **If its fusoform, indole +, grows anaerobic only and fluoresces green its this--if not its fuso spp) |
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F. necrophorum Clin Sig |
*serious soft tissue infection *GS: spherical areas w/in cells *fluoresce green |
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F. necrophorum ID |
*Ind/ Lipase + *cat/ nit - *id disc (V resis) |
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F. mortiferum Clin sig |
*normal gut flora *GS: coccoid to filamentous, spherical swellings *fluoresces green |
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F. mortiferum ID |
*BBE+ *ID disc (V resis) |
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Spore forming GPBacilli |
*Clostridium spp |
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Clostridium perfringens clin sig |
*most common clostridium isolated from clin spec *soil contaminant (GI colonlizer) *wound contaminant, cellulitis, food poisoning etc |
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C. perfringens myonecrosis |
*causes 80% of Gas gangrene |
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C. perfringen food poisoning |
*improperly cooked meat *spores survive initial cooking germinate and vegetative cells proliferate during cooling *toxin release after ingestion *relatively mild, resolves in 2-3 days |
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C. perfringens GS |
*Gram variable strait rods w/ blunt ends *"Box car" *central to subterminal spore |
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C. perfringens Morph |
*grey to greyish yellow, circular, glossy, dome shaped *DOUBLE ZONE B HEMOLYSIS *Lecithinase + on EYA |
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C. difficile Clin Sig |
*antibiotic associated diarrhea *Most freq. id cause of hospital acquired diarrhea *Can cause pseudomembranes adherent to the colon |
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C. difficile ID |
*GS: GPR, spore is subterminal *can be isolated on CCFA *toxin assay |
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C. septicum Clin Sig |
*Isolation from blood cultures assoc. w/ underlying disease process! -leukemia, lymphoma, carcinoma *other contributing conditions include diabetes mellitus |
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C. septicum SBA |
*swarms after only 24 hrs! |
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C. tetani Clin Sig |
*causes 'Lock jaw' *spores throughout *produces neurotoxin which causes muscle spasms, exhaustion, respiratory failur *tetanus occurs mostly in nonimmunized peeps |
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C. tetani ID |
*rarely isolated in clin spec. Dx based on symptoms and history *GPR *swollen terminal spore *flat, grey, matte surface, narrow band of hemolysis |
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C. botulinum Clin Sig. |
*botulism *extreme neurotoxin causes flaccid paralysis and death *other forms of botulism: -colonization -infant -wound |
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Diagnosis of botulism |
*made from isolation of organism from stool or detecting the toxin in serum, stool or food |
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Other clostridium spp |
*spore formation aids in classification *EYA may be useful |
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Nonspore forming GPR |
*actinomyces spp *Propionibacterium spp *mobiluncus spp |
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Actinomyces spp Clin Sig. |
*found in soil and on mucous membranes or humans and animals *opportunistic pathogens *Actinomyces israelii is the most common |
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Actinomycosis |
*chronic granulomatous lesion that becomes suppurative and forms abscesses and draining sinuses *Sulfur granules |
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Actinomyces israelii Gram Stain |
*Branching, filamentous GPR |
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Actinomyces spp ID |
*clinicians must indicate when they want to rule out actinomycosis *SBA: MOLAR TOOTH *facultative anaerobes (some strict)
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Propionibacterium spp Clin Sig |
*slow growing *normal skin flora, NP, oral cavity, GI and GU *freq. blood culture contaminant *rare cause of endocarditis, CNS shunt, and other infections |
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Propionibacterium acnes |
*pathogen in shoulder arthroplasty *associated w/ inflammatory process of acne
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Propionibacterium propionicum |
*can cause actinomycosis |
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Propionibacterium spp GS |
pleomorphic coryneform rods |
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Propionibacterium acnes ID |
*sm. white colony, smooth to rough *Catalase + (only one) *indole + (indole - would be propionibacterium spp) |
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Mobiluncus spp Clin Sig |
*Bacterial vaginosis *not practical to culture *Presumptive ID called from direct smear *Curved GVR's with tapered ends |
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Anaerobic Cocci |
1. Peptostreptococcus spp (GPC) 2. Veillonella spp (GNDC) |
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Peptostreptococcus spp Clin Sig |
*skin, urethral, and urogenital flora *often found in mixed infections (Cutaneous, respiratory, oral, or female pelvic) *Presumptive ID made based on gs and anaerobic growth
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Peptostreptococcus Plate and ID |
*GPC *tiny peaked colonies *P. anaerobius is SPS sensitive (found in blood culture) |
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Veillonella spp Clin Sig |
*normal in mouth, vagina, Upper respiratory and GI tract *May be found in mixed infections *head, neck, dental, and pulmonary infection; bite wounds |
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Veillonella spp GS and plate |
*tiny diplococci *slight brick red fluorescence (it fades quickly) |
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Veillonella spp ID |
*small on BRU *sm., tranlucent or opaque on BAP *no growth on BBE and LKV *Nitrate + (bacteroides is the only other +) |
