Anaerobes Flashcards
Describe synergy between aerobes and anaerobes
Aerobes colonize and utilize oxygen, producing anaerobic conditions for aerobes to colonize
List some clinical findings that suggest that anaerobes are present
- syndrome recognition
- failure to respond to antibiotics that don’t cover anaerobes
- sterile pus- positive gram stain but negative culture
Describe principles of treatment of anaerobic infections
- source control, debridement
- antibiotics
- active or passive immunity for toxin mediated disease
List antibiotics that are generally rated “A+” for anaerobes
metronidazole carbapenems beta lactamase inhibitor combinations tigercycline moxifloxacin
Describe the use of clindamycin in anaerobic infections
A+ above the diaphragm
C below the diaphragm
Describe the use of vancomycin and penicillin in anaerobic infections
good for gram positive only
Describe the use of cefoxitin in anaerobic infections
moderate activity
Describe mechanisms by which anaerobes cause disease
- mucosal barrier disruption
- devitalized tissue
predisposing infections: malignancy, occlusion, vascular disease, diabetes, trauma, immune compromise, foreign bodies, antibiotics that select out anaerobes
Differentiate Bacteriodes fragilis from other Bacteroides
Bacteroides fragilis: most commonly isolated anaerobe, found in abscess, increasing drug resistance through beta lactamases
Other Bacteroides: mouth and GU tract
Describe the appearance, location, and pathogenicity of Fusobacterium
Fusobacterium necrophorum- long thin rods, mouth and gingival flora, active endotoxin
Describe the appearance, location, and pathogenicity of Peptostreptococcus
Secondary to B fragilis in frequency of recovery from clinical isolates, found in mouth, GI, GU tracts, nearly always found with mixed flora
List aerobes and anaerobes that are oral cavity flora
aerobes: streptococci, lactobacilli, staphylococci, cornyebacteria
anaerobes: bacteroides, fusobacterium, prevotella, peptostreptococcus, porphyromonas
Poor ____ is a risk factor for increased concentrations of anaerobes in the oral cavity
dentition
gingival crevices, tonsillar and tongue crypts, dental plaques
List foci of spread of dental ifnection
vestibular abscess–> buccal space, palatal abscess, sublingual space, submandibular space, maxillary sinus
___________ is a mixed infection of the submandibular space
Ludwig’s angina
_________ is an infection with Fusobacterium necrophorum that leads to jugular vein thrombosis and septic emboli
Lemierre’s syndrome
List lab findings that indicate presence of anaerobic infection (ex to distinguish from malignancy)
Many PMNs
no squamous epithelial cells in sputum sample (marker of good sample)
Many GPC, GNR, GPR
List factors that lead to anaerobic lung infections
Oral anaerobes mixed with aerobes (Prevotella, Fusobacterium, Peptostreptococci, Bacteroides)
Poor dentition, gingival disease
Commonly misdiagnosed as malignancy or TB
List signs of anaerobic lung disease
constitutional symptoms- weight loss, anorexia, night sweats
fetid sputum
List treatment for anaerobic lung infections
Weeks-months of antibiotics
Define and describe empyema
Infection of pleural space
Pleural fluid will have low pH, low glucose, high LDH, and positive gram stain or culture
Treat with drainage, antibiotics, decortication if necessary
In the _____, anaerobes outnumber aerobes 1000:1
colon
List two major types of intra-abdominal anaerobic infections
Peritonitis (perforated viscus)
Abscess (intraperitoneal or visceral)
List steps for management of intra-abdominal abscess
Drainage- percutaneous catheter, surgical
Antibiotics
The terminal spore of ____________ is extremely hardy and found in soil or animal intestinal tracts
Clostridium tetani
How does the tetanus syndrome develop
- spores enter via wound
- incubation average 8 days
- proliferate under low O2 conditions
- produces toxin which disseminates through blood and lymphatics
_____ toxin enters the nervous system at presynaptic terminals of lower motor neurons, and is carried in a ______ direction to the CNS. It prevents neurotransmitter release from _____ cells.
Tetanus
Retrograde
Inhibitory
Generalized tetanus proceeds in a ___ pattern, causing trismus, neck stiffness, problems swallowing, abdominal muscle rigidity, and spasms
Descending
List complications of tetanus
Laryngospasms Fractures Autonomic hyperactivity Pulmonary embolism Aspiration pneumonia
Describe components of treatment for tetanus
Muscle relaxants, HTIG, antibiotics, wound debridement
List some features of “tetanus prone” wounds
Older, stellate configuration, deeper, crush/ burn/ frostbite, contaminated, devitalized tissue present
The ___ toxin prevents release of acetylcholine and causes weakness in the motor system and dysfunction in the autonomic systme
Clostridia botulinum
The ____ spore is a subterminal spore that is heat stable and found in soil and marine environments
Closdridium botulinum
List mechanisms of infection for the different types of botulism
- foodborne: ingest preformed toxins from canned foods, fish, fruits
- infant: ingest spores in honey or soil
- wound: spores germinate in wound
- inhalational: toxin (bioterrorism)
Describe clinical features of botulism
- acute bilateral cranial nerve dysfunction
- descending motor weakness
- patient is alert and afebrile
Describe treatment for botulism
Trivalent antitoxin available from CDC
Wound debridement
Antibiotics
List soft tissue infections caused by clostridia species
Gas gangrene, clostridium perfringens
Treat with early and aggressive surgical debridement, penicillin, clindamycin
Clostridium ____ produces spores that can germinate under favorable environmental conditions and produce exotoxins A and B to cause mucosal damage and diarrheal illness
difficile
–> pseudomembranous colitis
_______ is the most common cause of unexplained leukocytosis in hospitalized patients
C diff
Clostridium _____ causes food poisoning by producing a toxin in vivo (NOT pre-formed); vomiting is rare
Perfringens
