GP anaerobes

anaerobic GPRs

* found in GI/GU tracts, oral cavity, skin
* differentiate by spore production

aerotolerant clos (histolytica, tertium, canis)

* pos: anaerobic spores


* neg: cat, aerobic spores

bacillus sp

* pos: cat, aerobic spores
* neg: anaerobic spores

GNRs

vanc R, colistin S

GPCs

vanc S, colistin R

clostridium spp

* large, GPR spore forming
* ubiquitous (soil)
* aerotolerant: histolyticum, tertium, carnis
* fluoro: c. diff, innocuum = chartreuse; ramosum = red
* exogenous infections: wounds, organism, toxin ingestion (except c.diff)
* antibiotics can prevent growth on artificial media

fluorescence

* wood’s lamp
* may need longer incubation or exposure to O2
* a. odontolyticus red
* veillonella brick red

c. perfringens diseases

* food poisoning
* gas gangrene (clos myonecrosis)

food poisoning - c. perfringens

* ingestion of spores from contam food = enterotoxin made in GI
* beef, poultry, gravies, dried/precooked foods
* large amts of food made (hospitals, cafeterias, events)
* watery diarrhea, adb cramps, 8-12 hrs, self resolving

clostridial myonecrosis - c. perfringens

* traumatic injury, entry of vegetative bacteria/spores in wound
* vascular damage = improper perfusion = lack of O2 = anaerobic
* sudden pain, skin pale = bronze = purple red
* bullae develop (black bubbles)
* tachy, fever, shock, organ failure, IV hemolysis, jaundice, renal failure, hypotension, liver necrosis

c. perfringens toxins

* alpha toxin: phospholipase C and sphingomyelinase
* theta (perfringolysin O): pore forming

morphology of c. perfringens

* boxcar GPR with rare subterminal spores
* double zone hemolysis (inner = theta) (outer = alpha)

presumptive ID - c. perfringens

* growth on anaBAP: large, irregular, double zone, boxcar, square rods; no indole
* additional:
* pos: gelatin, lecithinase, stormy litmus ferm, rvs CAMP
* neg: motility, urease, lipase, proteolysis litmus

which clostridium are lipase pos

c. botulinum, sporogenes, noyvi

litmus milk

* determine metabolic activity of microbes in milk (esp for clos)
* skim milk substrate, azolitmin pH (pink acid; blue alk)
* no change: no carb ferm
* alk: proteolysis of lactalbumin (pos)
* acid: ferm of lactose and/or dextrose (stormy - gas)
* clot formation: coag of casein
* clot dissolution: peptonization of milk protein

spore induction - heat method

* inoculate 2 tubes of starch broth and heat 1 for 10 min at 70C
* incubate both 37C anaerobic
* if growth in both = spores induced

spore induction - ethanol test

* mix week old TG broth with 95% EtOH
* sit at RT 30 min and sub to anaBAP (incubate anaerobically 48 hrs)
* growth = spores produced

tetanus - c. tetani

* spores enter tissue and vegetate, producing tetanospasmin
* four types: generalized, local, cephalic, neonatal

tetanospasmin

* 2nd most toxic sub
* carried thru to nerves, spinal cord, brain stem
* binds to neuronal receptors irreversibly, blocks signals to inhibit motor responses (GABA) = spastic paralysis

generalized tetanus

* trismus (lockjaw) + irritability, restlessness, sweating, tachy
* progresses with contraction of skeletal muscles + spasms
* stiff neck, opisthotonus, risus sardonicus, rigid abd, dysphagia, apnea, airway obstruction from muscle contraction

local tetanus

* rare; muscle tonicity/spasms isolated to one region of body
* progresses to generalized

cephalic tetanus

* in head/neck regions due to injury, progressing to generalized
* dysphagia, trismus, focal cranial neuropathies can misDx as stroke

neonatal tetanus

* failure in aseptic techniques in delivery/umbilical stump management
* cultural practices: ghee, juices, cow dung
* unclean hands/environment
* onset faster; begins with refusal to feed (trismus)

c. tetani morph

* GPR terminal spores; drumstick, tennis racket
* swarming on anaBAP

presumptive ID of c. tetani

* smoothly swarming, slow growing, swollen terminal spores, indole pos
* additional:
* pos: motility, gelatin
* neg: lecithinase, lipase, proteolysis, acid from lactose, urease
* V: indole

c. botulinum

* botulism: spores enter body thru wounds, ingestion, inhalation which vegetate in tissue and make exotoxin
* five types: infant, foodborne, wound, adult infectious, bioterrorism assoc

botulism toxin

* most potent toxin to man
* carried to nerves, spinal cord, brain stem
* moves across presynaptic nerve terminal membrane
* breaks down neuronal SNARE proteins that are supposed to release Ach to stimulate motor responses = flaccid paralysis

infant botulism - floppy baby syndrome

* ingestion of clostridial spores move to GI tract and germinate and produce toxin
* common form in US
* constipation, weakness, feeding difficulties, hypotonia, drooling, anorexia, irritability, weak cry, dyspnea

foodborne botulism

* ingestion of preformed toxin in contam food (canned goods)
* 2nd most common in US
* nausea, vomiting, adb pain, diarrhea, dry mouth, sore throat
* blurred vision, diplopia, nystagmus, dysphagia, muscle weakness, dyspnea

wound botulism

* bacteria/spores enter thru skin and tissue trauma
* same symptoms as foodborne w/o prodromal

adult infectious botulism

* arises from enteric colonization by the bacteria
* symptoms like infant form
* botex used for cosmetics and migraines

bioterrorism assoc botulism

* theoretical delivery of botulinum toxin via aerosol or food
* similar symptoms to generalized

morphology of c. botulinum

* GPR w subterminal or eccentric spores
* large, rough appearing on anaBAP

c. botulism lab dx

* based on symptomology (cx done by ref lab)
* sero or molecular methods
* phenotypically similar to c. sporogenes, but makes a neurotoxin
* ELISA, PCR, PGFE, GLS
* lipase pos (so is c. noyvi)
* dx from stool (organism or toxin)

c. diff

* no O&P after 3 days in hospital (CAP requirement)
* after taking antimicrobials (clindamycin, fluoroquinolones)
* advanced age and proton pump inhibitors also inc risk

c. diff toxins

* toxin A enterotoxin: causes inflammation leading to fluid secretion, mucosal injury
* toxin B cytotoxin: induces cellular apoptosis, necrosis

CDAD

* watery diarrhea hallmark, lower abd pain, fever, nausea, anorexia, leukocytosis
* pseudomembranous colitis: damage to colon leads to bloody stools, hypotension, bowel perforation, peritonitis
* toxic megacolon: diffuse ulcerations, nodules, superficial plaques

how to treat c. diff

* new superbug R to metronidazole
* oral vanc: not absorbed so it works, but expensive
* fecal transplant

c. diff morphology

* thin GPR with rare subterminal spores
* large, ground glass colony on ana BAP, horse stable odor
* chartreuse fluro
* grow on CCFA at 35C yellow colonies

c. diff presumptive ID

* large, flat, horse manure smell, chartreuse fluoro; thin rods rare spores; indole neg
* additional:
* pos: motility
* neg: lecithinase, lipase, proteolysis, gelatin, acid from lactose, urease

lab dx of c. diff

* do not perform cx
* old gold standard: cytotoxin neutralization test on human foreskin
* current: PCR and EIA

other clos species

* septicum: cecum cancer, medusa head
* sordelli: septic miscarriage
* tertium: aerotolerant, terminal spores

actinomycosis - actinomyces

* normal flora in oral cavity and GI tract; bacteria enter thru trauma sites
* form a mass in affected area, usually in mandible (misDx as cellulitis)
* bluish/red swelling progressing to abscess, fistulae, draining sinus tracts
* sulfur granules in yellow exudate

a. israelii

most common isolate, slow grower, molar teeth

a. odontolyticus

red pigment enhanced with air exposure

a. naeslundii

colonies produce tan pigment with prolonged incubation

a. visocosus

pos catalase

a. meyeri

small GPR, strict anaerobic (QA organism)

actinomyces ID

* branching GPR, stain from exudate, sulfur granules
* differentiation not done

bifidobacterium

* normal GI, vaginal, oral flora
* rare resp, UTIs, dental caries
* assoc w probiotics
* bifurcated ends, Y shaped GPR

eubacterium

rare infections (oral flora) teeth, human bite, polymicrobic vaginal infections

lactobacillus

* bacteremia, endocarditis, dental caries in IC
* normal vaginal flora
* some aerotolerant
* long thin GPR in chains
* cat neg
* vanc R

mobiluncus

* polymicrobial BV
* curved GPR (like vibrio)
* motile

proprionibacterium

* skin flora in sebaceous glands = common contam in skin and blood cx
* endocarditis, implanted prosthetic devices

presumptive ID - p. acnes

* small, opaque enamel white, circular colonies
* cat pos w 15%
* coryneform (diphtheroid like) spiders
* indole pos

anaerobic GPC

* normal mouth, URT, GI, female GU, skin flora
* opportunistic polymicrobial infections: skin, oral, brain, bacteremia, necrotizing pneumonia, septic abortion
* anaerococcus, finegoldia, peptoniphilus, peptococcus, peptostreptococcus

anaerococcus

* a. prevotii: urease neg
* a. tetradius: urease pos

f. magna

greater than 0.6um

peptoniphilus

* p. asaccharolyticus: nitrate neg, indole pos
* p. indolicus: nitrate pos, indole pos

peptococcus

black colonies rarely isolated in cx

peptostreptococcus

* anaerobius most common: SPS sensitive so not recovered in blood cx
* p. micros < 0.6um

staphylococcus saccharolyticus

anaerobe

v. parvula

nitrate pos