MIcro solo 9

Anaerobes general characteristics

Strict or obligate anaerobes do not grow in the presence of oxygen, aerotolerant anaerobes are capable of growth in the presence of oxygen, but grow better in anaerobic conditions, certain specimens should be rejected bc of overgrowth of normal anaerobic flora, gas mixture to maintain anaerobic conditions in the hood uses 5% CO2, 10% hydrogen, 85% nitrogen

Habitat and mode of transmission of anaerobes

most anaerobes that cause infections are also apart of our normal flora, endogenous anaerobes: soil and environmental inhabitants, exogeneous anaerobes: not considered normal human flora, ingestion of preformed toxins: Botulism (Clostridial), person to person spread: health care associated spread of Clostridiodes difficile

Anaerobic media

Anaerobic blood agar (ANA BAP), Lakes kanamucin vancomycin (LKV): Prevotella and Bacteroides species, Thioglycollate broth, Chocolate media: Growth on CAP: Aerobe, no growth: anaerobe

Anaerobic identification disks

Kanamycin, Colistin, Vancomycin: gram positive organisms are susceptible and gram negative are resistant, Bile, Nitrate and SPS (gram-positive), spot tests are then used to further identify: Indole and catalase

Spectrum of disease anaerobic gram-negative rods

most commonly encountered in anaerobic infections, infections are often polymicrobial, hallmark of most infections is the production of foul odor, Bacteriodes fragilis group typically infects below the diaphragm, other gram neg rods typically involved in head, neck, and pleuropulmonary infections

Bacteroides fragilis group identification

some can resemble a safety pin, Kanamycin resistant, Vancomycin resistant, colistin resistant, bile positive, indole negative

Bacteroides species, not fragilis identification

Kanamycin resistant, Vancomycin resistant, Colistin resistant, bile positive, catalase negative, indole positive

Prevotella species identification

LKV can show a black pigment depending on the species, Kanamycin resistant, Vancomycin resistant, colistin variable, bile negative, catalase negative, indole variable

Porphyromonas identification

Kanamycin resistant, Vancomycin susceptable, Colistin resistant, Bile negative, Catalase negative, Indole positive

Fusobacterium nucleatum identification

rods with sharply pointed edges, Bread crumb-like, greening of agar on exposure to air, Kanamycin susceptible, Vancomycin resistant, Colistin susceptible, Bile negative, Indole positive, catalase negative

Fusobacterium necrophorum

gram neg with tapered ends, greens the agar on exposure to air, Kanamycin susceptable, Vancomycin resistant, Colistin susceptible, Bile positive, indole positive, catalase negative, Lemierres syndrome - upper respiratory, neck jaw - peritonsillar abscess

Spectrum of disease for Anaerobic gram pos cocci

most often found mixed with other anaerobic and facultative anaerobic bacteria in cutaneous, respiratory, oral or female pelvic infections

Finegoldia magna identification

resembles Staphylococci (gram pos cocci in pairs or clusters), Kanamycin susceptible, Vancomycin susceptible, Colistin resistant, SPS resistant, Nitrate negative

Parvimonas micra identification

Kanamycin susceptible, Vancomycin susceptible, colistin resistant, SPS susceptible, nitrate negative

Peptostreptococcus anaerobius identification

Kanamycin resistant, Vancomycin susceptible, colistin resistant, SPS susceptible nitrate negative

Veilonella species identification

main anaerobic gran neg cocci or diplococci, Kanamycin susceptible, vancomycin resistant, colistin susceptible, bile negative, nitrate positive, indole negative, catalase variable

Clostridium perfrigens virulence factors and spectrum of disease

Alpha toxin, Gas gangrene (myonecrosis) and necrotizing fasciitis

Clostridium perfringens identification

Boxcar shape, exhibit double-zone hemolysis, Kanamycin susceptible, vancomycin susceptible, colistin resistant, indole negative, catalase negative, gelatin positive, Lecithinase positive, lipase negative, Esculin variable, nitrate varibale

Clostridium botulinum virulence factors and spectrum of disease

produces an extremely potent neurotoxin (BoNT), foodborne botulism and infant botulism

Costridium botulinum identification

resembles a tennis racket, gelatinase positive, lecithinase negative, lipase positive, indole negative, esculin positive, nitrate negative

Clostridium tentani virulence factors and spectrum of disease

produces tetanospasmin (TeNT): neurotoxic exotoxin that disrupts nerve impulses to muscles, Tetanus also known as lockjaw

Clostridium tetani identification

resembles drumsticks, gelatinase positive, lecithinase negative, lipase negative, indole variable, esculin negative, nitrate negative

Clostridioides difficile virulence factors and spectrum of disease

produces toxin A (enterotoxin) and toxin B (cytotoxin), organism requires diminished normal gut flora by the various antimicrobial agents to become established in the gut of hospitalized patients, once established elaboration of one or more toxin results in antibiotic-associated diarrhea or potentially life-threatening inflammation of the colon, inflamed bowel is overlaid with pseduomembrane debris the disease is referred to as pseudomembranous colitis, only strains that produce toxin A or B or both cause infections

Clostridoides diffucile identification

produces a horse-stable or barnyard odor, gelatinase positive, lecithinase negative, lipase negative, indole negative, esculin positive, ntirate negative

Actinomyces species virulence factors

infections usually require disruption of the protective mucosal surface of the oral cavity

Actinomyces species identification

Dipth-like (gram pos, branching, beaded, thin filamentous rods), presence of purulent exudate of sulfur granules when crushed to reveal the dipth-like rods is diagnostic

Actionmyces isrealii

Diphth-like, colonies are white opaque and may resemble a molar tooth

Propionbacterium acnes

called anaerobic dipthriods (gram pos, pleomorphic, dipth-like rod), young colonies are small and white to gray and become larger and more yellowish tan with age, Kanamycin susceptible, vancomycin susceptible, colistin resistant, indole positive, catalase positive, nitrate positive

Bifidobacterium species identification

bifurcated ends that resemble dog bones, Kanamycin susceptible, vancomycin susceptible, colistin resistant, indole variable, catalase negative, nitrate negative

Eggrethella lenta identification

Kanamucin susceptible, Vancomycin susceptible, colistin resistant, indole negative, catalase negative, nitrate positive

Antimicrobial susceptibility testing for anaerobic organisms

susceptibilies also take 48 hours to interpret, Bacteroides species are intrinsically resistant to penicillin

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