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Microbiology- Unit Two
Anaerobic Infection (T Pierce)
43
Medical
Professional
10/08/2009

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Term
examples of obligate anaerobies
Definition
  • Bacteroides
  • Clostridia
Term
Mechanism of anaerobe discovery in culture and how it is preserved
Definition
  • dependent on specimen handling and culture techniques
    • exclude air from specimen
    • anaerobic transport media can be utilized
    • specimen should be promptly delivered to lab
    • special jar, chamber to culture where oxygen can be excluded
Term
Where would we find anaerobic bacteria in normal body flora
Definition
  • mucosal surfaces
    • oral cavity
    • GI tract (dominate in distal ileium and colon while aerobes found more in proximal GI tract)
    • upper resp. tract
    • femal GU tract
Term
medically important anaerobes in the flora
Definition
  • gram neg. rods- bacteriods, fusbacterium, prevotella
  • gram pos. rods- clostridia (spore forming), actinomyces (non spore forming)
  • gram pos. cocci- peptococcus, peptostreptococcus
  • gram neg. cocci- veillonella
Term
place in body with primarily aerobic flora
Definition
  • skin
  • eye
  • urethra
Term
predisposing conditions/clinical characteristics of anaerobic infections
Definition
  • secondary invaders from normal flora
  • predisposing conditions
    • tissue destruction- tumor, trauma, vascular insufficiency (all lead to tissue anoxia and low oxygen tension)
    • antecedent aerobic infection
  • complex polymicrobial
  • foul smell
  • gas in tissue
  • abscess formation
Term
cause of intraabdominal sepsis
Definition
secondary to breach in colon
Term
sources of intra-abdominal or pelvic infection
Definition
  • perforated appendix or diverticulum
  • perforated colon cancer
  • gunshot to abdomen
  • post-op infection
Term
pathophysiology of intraabdominal sepsis according to rat model and what can prevent the various stages from occuring
Definition
  1. breach in colon
  2. leads to fecal material being released into peritoneal cavity
    1. contains many anaerobic species
    2. usually Bacterioides fragilis and E coli
  3. two stages
    1. peritonitis stage- 40% mortality (dominated by E coli)
      • prevent death via antibiotics
    2. abscess stage after 7-14 days (dominated by B. fragilis)
      • must use antibiotics that will work against this bacteria to prevent abscess formation
Term
Ludwig's angina (cause, def., predisposing factors)
Definition
  • definition- infection in submandibular space (sublingual, submylohyoid)
  • predisposing factors
    • odontogenic infection
    • trauma
    • mandibular fracture
    • foreign bodies
    • neoplasm
  • causative agents
    • mixed oral aerobes, anaerobes
    • sometimes S. aureus
Term
Clinical features of Ludwig's angina
Definition
  • mouth pain
  • drooling
  • dysphagia
  • resp. distress
  • hot potato voice
  • edema on floor of mouth with swelling and displacement of tongue post. and sup.
  • woody tender swelling of suprahyoid region of the neck
Term
predisposing conditions of anaerobic pneumonia/ lung abscess
Definition
  • altered consciousness
    • alcoholism
    • general anesthesia
    • drug overdose
  • esophageal dysfunction
  • tonsillectomy/tooth extraction
Term
lung abscess clinical features and tx
Definition
  • present with cough, fever, coppious foul smelling sputum
  • chest X ray with cavitation with air/fluid level
  • sputum gram stain shows mixed gram negative and positive organisms
  • increased incidence of penicillin R
  • clindamycin most effect
Term
reliable diagnosis specimens in bacterial pulmonology infections
Definition
  • blood cultures
  • direct lung punctures
  • thoracotomy aspirates
  • empyema fluid
  • percutaneous transtracheal aspiration
  • bronchospcopy with protected brush
Term
etiology of lung abscess
Definition
  • mix of anaerobes and aerobes
  • shown that anaerboes were by far dominant
  • common aerobes- Strep. pneumonia, S. aureus, E coli
  • common anaerobes- Clostridium, Bacteriocides
Term
predisposing factors to brain abscess
Definition
  • otitis media
  • sinusitis
  • dental infection
  • pneumonia
  • abdominal/pelvic infection
  • endocarditis (S aureus, Strep.)
Term
etiology of brain abscess
Definition
  • primarly caused by oral flora
    • 85% anaerobe
      • gram positive cocci
      • Fusobacterium, Bacteroids
  • in setting of endocarditis- S aureus, Viridans Strep
Term
clinical presentation of brain abscess
Definition
  • subacute symptoms
  • fever, altered sensorium
  • focal neurologic defects
  • increase intracranial P, papilledema
Term
diagnosis of brain abscess
Definition
  • imaging via CT, MRI
  • aspiration and gram stain, culture
  • blood culture
  • CI: lumbar puncture due to risk of increased intracranial P
Term
examples of localized anaerobic soft tissue infections
Definition
  • DM, vascular ulcures
  • decubitus ulcers
  • human bites
  • hydradenitis suppurtiva
  • Meleney synergistic gangrene
Term
examples of diffuse infections in soft tissue caused by anaerobes
Definition
  • anaerobic cellulitis
  • necrotizing faciitis
  • synergistic necrotizing cellulitis
  • myonecrosis syndromes
Term
risk factors of DM soft tissue infection
Definition
  • neuropathy- loss of sensation
  • vasculopathy- impaired blood flow
  • immunopathy- impaired WBC function
Term
compare and contrast the two types of necrotizing fasciitis
Definition
  • mixed
    • rapid progression, substantial mortality
    • maybe subtle skin findings initially
    • pain out of proportion to clinical findings
  • group A strep
    • more rapid progress, higher mortality
    • may have no skin findings
    • even more painful
Term
Epidemiology, char, toxicology of clostridia
Definition
  • epidemiology- ubiquitous in soil, water, sewage (part of normal flora)
  • char- gram positive spore forming bacilli
  • produce multiple toxins
    • cytotoxins
    • enterotoxins
    • neurotoxins
Term
Clostrium perfringes (toxins, what it causes)
Definition
  • gas gangrene (Clostridial myonecrosis)
    • 12 toxins/enzymes
    • alpha toxin- via PLC, causes hemolysis (cytotoxic)
  • food poisoning
    • enterotoxin (heat labile toxin released during spore formation)
Term
clinical features of gas gangrene
Definition
  • clincial syndrome char. by severe pain and marked toxicity
  • patients alert with impending sense of doom
  • usually with antecedent trauma
Term
Gas gangrene dx
Definition
  • make dx clinically (never via microbiologic dx)
  • palpable if cause is C repitus
  • visualize via X ray, CT, MRI
  • Term
    causative agents of gas in tissues
    Definition
    • anaerobes- Bacteroids, Clostridia, anaerobic strept.
    • aerobes if high glucose
      • enterobacteriaciae
    Term
    danger signs of gas gangrene
    Definition
    • severe pain
    • severe systemic toxicity
    • hypoesthesia
    • ecchymoses or bullae
    • soft tissue gas
    • rapid extension
    Term
    Char., toxins of C. tetani
    Definition
    • char.- anaerobic spore forming rod
    • tetanospasmin- dimeric toxin
      • neurotoxin (produced during stationary phase of growth)
      • block inhibitory transmitter release at inhibitory synapse in spinal cord (ex: GABA, Gly)
    Term
    different types of tetanus and incubation period
    Definition
    • incubation- seven days usually (0-90 day range)
    • localized- muscle spasms localized to area of primary infection
    • generalized- lockjaw, persistent back spasm, autonomic dysfunction
    • neonatal- associated with infection of umbilical stump (mortality 90%)
    Term
    tx, px of tetanus
    Definition
    • wound debriment
    • antibiotics
    • passive immunization (tetanus IG)
    • active immunization (tetanus toxoid)
    Term
    C. botulinum (char, VF)
    Definition
    • characteristics- spores heat resistent, present in soil
    • VF- botulism toxin
      • type A, B, E
        • indiv. isolates prod. only one toxin
        • type E with aquatic animals
      • block ACh release at motor end plates leading to paralysis
    Term
    botulism (sources and what associated with)
    Definition
    • food born (preformed toxin)
      • associated with ingestion of home and commercially canned foods
    • infant toxin formed in vivo (MOST COMMON IN US)
      • associated with honey ingestion
    • wound toxin formed in vivo
      • associated with IV drug use
    Term
    foodborn botulusm (clinical symptoms, incubation period)
    Definition
    • anticholinergic effects- vomitting, dry mouth, dilated pupils
    • CN paralysis
    • descending flacid motor paralysis
    • incubation: 12-36 hrs
    Term
    tx botulism
    Definition
    • remove toxin (gastric lavage, wound debridment)
    • resp. support
    • polyvalent equine antitoxin
    Term
    Where are most of botulism cases in US? Why
    Definition
    • Alaska
    • traditional native foods ferment in conditions that favor spore forming bacteria
    Term
    C dificile (char, VF)
    Definition
    • Char- spore forming, gram positive anaerboic bacillus (asymp. in colonic floor of most people)
      • spores persist for months in envir.
    • VF- enterotoxin (A) and cytotoxin (B)
    Term
    C difile associated with what clinical syndrome
    Definition
    antibiotic associated diarrhea
    Term
    Antibiotic associated colitis (pathogenesis)
    Definition
    1. antibiotic therapy
    2. up to six weeks after, alter colonic microflora
    3. germination of C dificile spores
    4. release toxin A and B from spore forming coat
    5. colonic mucosal injury and inflammation
    Term
    clinical manifestations of C difficile associated colitis
    Definition
    • symp.
      • profuse watery diarrhea
      • abdominal pain
      • leukocytosis
      • fever
    • complication
      • dehydration
      • electrolyte disturbance
      • shock
      • toxic megacolon
      • reactive arthritis
    Term
    dx of C difficile associated diarrhea
    Definition
    • endoscopic appearance: pseudomembranes
    • fetal leukocytes in 50%
    • cytotoxic assay
    • ELISA for toxin A or B
    • NOT culture
    Term
    clinical management of C difficile associated colitis
    Definition
    • discontinue causative antibiotic
    • initiate effective antibiotic
      • metronidazole
      • oral vancomycin
      • rifaximin
      • toxin bindin resins
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