Anaerobes

Question 1

Describe synergy between aerobes and anaerobes

Answer 1

Aerobes colonize and utilize oxygen, producing anaerobic conditions for aerobes to colonize

Question 2

List some clinical findings that suggest that anaerobes are present

Answer 2

1. syndrome recognition
2. failure to respond to antibiotics that don’t cover anaerobes
3. sterile pus- positive gram stain but negative culture

Question 3

Describe principles of treatment of anaerobic infections

Answer 3

1. source control, debridement
2. antibiotics
3. active or passive immunity for toxin mediated disease

Question 4

List antibiotics that are generally rated “A+” for anaerobes

Answer 4

metronidazole
carbapenems
beta lactamase inhibitor combinations
tigercycline
moxifloxacin

Question 5

Describe the use of clindamycin in anaerobic infections

Answer 5

A+ above the diaphragm

C below the diaphragm

Question 6

Describe the use of vancomycin and penicillin in anaerobic infections

Answer 6

good for gram positive only

Question 7

Describe the use of cefoxitin in anaerobic infections

Answer 7

moderate activity

Question 8

Describe mechanisms by which anaerobes cause disease

Answer 8

• mucosal barrier disruption
• devitalized tissue

predisposing infections: malignancy, occlusion, vascular disease, diabetes, trauma, immune compromise, foreign bodies, antibiotics that select out anaerobes

Question 9

Differentiate Bacteriodes fragilis from other Bacteroides

Answer 9

Bacteroides fragilis: most commonly isolated anaerobe, found in abscess, increasing drug resistance through beta lactamases

Other Bacteroides: mouth and GU tract

Question 10

Describe the appearance, location, and pathogenicity of Fusobacterium

Answer 10

Fusobacterium necrophorum- long thin rods, mouth and gingival flora, active endotoxin

Question 11

Describe the appearance, location, and pathogenicity of Peptostreptococcus

Answer 11

Secondary to B fragilis in frequency of recovery from clinical isolates, found in mouth, GI, GU tracts, nearly always found with mixed flora

Question 12

List aerobes and anaerobes that are oral cavity flora

Answer 12

aerobes: streptococci, lactobacilli, staphylococci, cornyebacteria
anaerobes: bacteroides, fusobacterium, prevotella, peptostreptococcus, porphyromonas

Question 13

Poor ____ is a risk factor for increased concentrations of anaerobes in the oral cavity

Answer 13

dentition

gingival crevices, tonsillar and tongue crypts, dental plaques

Question 14

List foci of spread of dental ifnection

Answer 14

vestibular abscess–> buccal space, palatal abscess, sublingual space, submandibular space, maxillary sinus

Question 15

___________ is a mixed infection of the submandibular space

Answer 15

Ludwig’s angina

Question 16

_________ is an infection with Fusobacterium necrophorum that leads to jugular vein thrombosis and septic emboli

Answer 16

Lemierre’s syndrome

Question 17

List lab findings that indicate presence of anaerobic infection (ex to distinguish from malignancy)

Answer 17

Many PMNs
no squamous epithelial cells in sputum sample (marker of good sample)
Many GPC, GNR, GPR

Question 18

List factors that lead to anaerobic lung infections

Answer 18

Oral anaerobes mixed with aerobes (Prevotella, Fusobacterium, Peptostreptococci, Bacteroides)
Poor dentition, gingival disease
Commonly misdiagnosed as malignancy or TB

Question 19

List signs of anaerobic lung disease

Answer 19

constitutional symptoms- weight loss, anorexia, night sweats

fetid sputum

Question 20

List treatment for anaerobic lung infections

Answer 20

Weeks-months of antibiotics

Question 21

Define and describe empyema

Answer 21

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

Question 22

In the _____, anaerobes outnumber aerobes 1000:1

Answer 22

colon

Question 23

List two major types of intra-abdominal anaerobic infections

Answer 23

Peritonitis (perforated viscus)

Abscess (intraperitoneal or visceral)

Question 24

List steps for management of intra-abdominal abscess

Answer 24

Drainage- percutaneous catheter, surgical

Antibiotics

Question 25

The terminal spore of ____________ is extremely hardy and found in soil or animal intestinal tracts

Answer 25

Clostridium tetani

Question 26

How does the tetanus syndrome develop

Answer 26

- spores enter via wound - incubation average 8 days - proliferate under low O2 conditions - produces toxin which disseminates through blood and lymphatics

Question 27

_____ 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.

Answer 27

Tetanus Retrograde Inhibitory

Question 28

Generalized tetanus proceeds in a ___ pattern, causing trismus, neck stiffness, problems swallowing, abdominal muscle rigidity, and spasms

Answer 28

Descending

Question 29

List complications of tetanus

Answer 29

``` Laryngospasms Fractures Autonomic hyperactivity Pulmonary embolism Aspiration pneumonia ```

Question 30

Describe components of treatment for tetanus

Answer 30

Muscle relaxants, HTIG, antibiotics, wound debridement

Question 31

List some features of "tetanus prone" wounds

Answer 31

Older, stellate configuration, deeper, crush/ burn/ frostbite, contaminated, devitalized tissue present

Question 32

The ___ toxin prevents release of acetylcholine and causes weakness in the motor system and dysfunction in the autonomic systme

Answer 32

Clostridia botulinum

Question 33

The ____ spore is a subterminal spore that is heat stable and found in soil and marine environments

Answer 33

Closdridium botulinum

Question 34

List mechanisms of infection for the different types of botulism

Answer 34

- foodborne: ingest preformed toxins from canned foods, fish, fruits - infant: ingest spores in honey or soil - wound: spores germinate in wound - inhalational: toxin (bioterrorism)

Question 35

Describe clinical features of botulism

Answer 35

- acute bilateral cranial nerve dysfunction - descending motor weakness - patient is alert and afebrile

Question 36

Describe treatment for botulism

Answer 36

Trivalent antitoxin available from CDC Wound debridement Antibiotics

Question 37

List soft tissue infections caused by clostridia species

Answer 37

Gas gangrene, clostridium perfringens Treat with early and aggressive surgical debridement, penicillin, clindamycin

Question 38

Clostridium ____ produces spores that can germinate under favorable environmental conditions and produce exotoxins A and B to cause mucosal damage and diarrheal illness

Answer 38

difficile --> pseudomembranous colitis

Question 39

_______ is the most common cause of unexplained leukocytosis in hospitalized patients

Answer 39

C diff

Question 40

Clostridium _____ causes food poisoning by producing a toxin in vivo (NOT pre-formed); vomiting is rare

Answer 40

Perfringens