L7: Anaerobes & Peritonitis

Question 1

What is an example of a strict/obligate aerobe?

Answer 1

Pseudomonas aeruginosa

Question 2

What is an example of a facultative aerobe?

Answer 2

E. coli

Question 3

What is a microaerophilic organism? Give an example

Answer 3

grow poorly aerobically but distinctly better under 10% CO2 - e.g. Neisseria meningitidis

Question 4

What is an example of a strict/obligate anaerobe?

Answer 4

Bacteroides fragilis

Question 5

Which anaerobe(s) are present on the skin?

Answer 5

Propionibacterium acnes

Question 6

Which anaerobe(s) are present in the colon?

Answer 6

bacteroides spp.
clostridium spp.
prevotella spp.
peptostreptococcus spp.

Question 7

Which anaerobe(s) are present in the oral cavity + upper respiratory tract?

Answer 7

fusobacterium

peptostreptococcus spp.

Question 8

Which anaerobe(s) are present in the female genital tract?

Answer 8

lactobacillus spp.

Question 9

If someone was bitten by a dog, which anaerobe will most likely be present?

Answer 9

Capnocytophaga canimorsus

Question 10

What must be collected to make a diagnosis of an anaerobic infection?

Answer 10

1. Pus
2. Tissue Sample

both for culture

Question 11

What are host factors that may predispose a patient to anaerobic infections?

Answer 11

• impaired gag reflex + cough reflex
• trauma + tissue ischaemia
• gastrointestinal surgery
• amputation of lower limb in patient with peripheral vascular disease
• antibiotics

Question 12

Antibiotics alter the composition of the normal colonic flora, predisposing it to the overgrowth of…?

Answer 12

Clostridium difficile

Question 13

List some of the characteristics of the Clostridium spp.

Answer 13

• gram positive bacilli
• form spores
• produce exotoxin
• most are strict anaerobes

e.g. C. tetani, C. botulinum, C. difficile, C. perfringens

Question 14

What is the name of the toxin a/w Clostridium Tetani? What is its function/MOA?

Answer 14

Neurotoxin - Tetanospasmin

• blocks transmission at inhibitory synapse resulting in “inhibition of the inhibitory neurons”
• leads to sustained muscle contractions/spasms

Question 15

Briefly explain the pathogenesis of C. tetani

Answer 15

• skin trauma occurs (e.g. puncture wound, burns…)
• spores inroduced via skin trauma
• spores in wound germinate when there is a localized anaerobic environment
• they will then produce toxin

Question 16

Which organism was known to contaminate heroin?

Answer 16

Clostridium tetani

Question 17

What is the clinical presentation/symptoms of C. tetani?

Answer 17

muscle spasms - spontaneously or after minor stimuli
flexion of muscles e.g. arching of back
trismus - “lock jaw”
sardonic appearance

Question 18

What is another name for trismus?

Answer 18

Lock Jaw

Question 19

What pathogen is known for causing a sardonic appearance?

Answer 19

C. tetani

Question 20

What are some complication of a C. tetani infection?

Answer 20

laryngospasm
ANS dysfunction (labile BP, arrhythmias, sweating)

Question 21

What is the treatment/management plan for treating a patient with a C. tetani infection?

Answer 21

1. ABCs
2. Wound Debridement + Metronidazole
3. Tetanus Immunoglobulin
4. Manage Spasms
5. Avoid Touch, Light or Other Stimuli

Question 22

Which antibiotic is used when treating C. tetani?

Answer 22

Metronidazole

Question 23

What is the main prevention strategy for preventing a C. tetani infection?

Answer 23

Vaccination!

Toxoid Vaccine/Inactivated Tetanus Toxin Vaccine

Question 24

Why might a C. tetani booster immunization be required?

Answer 24

the vaccine may not provide protection after 10 years - so the patient will need a booster

Question 25

What is the name of the toxin a/w Clostridium Botulinum? What is its function/MOA?

Answer 25

"Botox" | - inhibits the release of ACh at NMJ resulting in weakness/acute flaccid paralysis

Question 26

How does foodborne botulism occur? (pathogenesis)

Answer 26

from poorly canned foods - foods that were not cooked thoroughly and then put in an anaerobic environment - spores germinate and toxin is produce - person ingests contaminated food - fast onset

Question 27

What is infant botulism? (pathogenesis)

Answer 27

- ingestion of spores that germinate in the GIT | - toxin then released in the GIT and absorbed

Question 28

What is the presentation/clinical features of botulism?

Answer 28

- symmetrical descending flaccid paralysis - bilateral cranial nerve palsies - double vision - difficulty swallowing - muscle weakness

Question 29

How does infant botulism appear?

Answer 29

- constipation - muscle weakness - lethargy - poor feeding - "floppy" baby

Question 30

What tests/investigation can be done to diagnose foodborne botulism?

Answer 30

detection of toxin in stool/vomitus

Question 31

What test/investigation can be done to diagnose infant botulism?

Answer 31

organism or toxin in stool

Question 32

What test/investigation can be done to diagnose wound botulism?

Answer 32

culture of organism from wound site

Question 33

What is the treatment/management for botulism?

Answer 33

1. ABCs 2. Antitoxin - Botulism Immunoglobulin 3. Wound Debridement + Metronidazole (only in wound botulism)

Question 34

C. difficile infections often occur in which population group?

Answer 34

in people who have had contact with healthcare or have been on antibiotics

Question 35

Antibiotics are known to knock out both good and bad bacteria in the gut - this can lead to a C. difficile infection. Which antibiotics have been most implicated with C. diff infections?

Answer 35

- Fluoroquinolones - Beta-Lactam Antibiotics (esp. ampicillin and 3rd generation cephalosporins) - Clindamycin

Question 36

What are some 3rd generation cephalosporins?

Answer 36

Cefotaxime, Ceftriaxone

Question 37

How may a C. diff infection be diagnosed?

Answer 37

PCR of stool for toxin gene (TCDB gene)

Question 38

What is the treatment/management plan for C. difficile infection?

Answer 38

1. Isolation + Contact Precautions 2. Review Antibiotics 3. Supportive Therapy 4. Antibiotics ( Oral Vancomycin OR Fidaxomicin)

Question 39

Which antibiotic is used to treat botulism?

Answer 39

Metronidazole

Question 40

Which antibiotics may be used to treat C. difficile infections?

Answer 40

Oral Vancomycin or Fidaxomicin

Question 41

What is clostridial myonecrosis another name for?

Answer 41

gas gangrene

Question 42

What toxin causes c. perfringens food poisoning?

Answer 42

C. perfingens enterotoxin

Question 43

What toxin causes c. perfringens gas gangrene?

Answer 43

Lecithinase toxin

Question 44

How can gas gangrene be diagnosed? What tests/investigations can be done?

Answer 44

- CT or XRAY (looking for gas in tissues) - Wound Swab or Blister Fluid for Culture - Blood Culture

Question 45

What is the treatment for gas gangrene?

Answer 45

- surgical debridement** | - high dose penicillin/clindamycin

Question 46

What is a risk factor for SBP?

Answer 46

cirrhosis of the liver (ascites)

Question 47

What organisms usually cause SBP?

Answer 47

Aerobic Bacteria (E. coli, K. pneumoniae, S. pneumoniae, GAS, enterococci)

Question 48

What organisms usually cause peritonitis complicating peritoneal dialysis?

Answer 48

Skin Flora - S. aureus, coag neg staph GI Flora - E. coli, pseudomonas

Question 49

What are the symptoms/clinical features of peritonitis complicating peritoneal dialysis?

Answer 49

- cloudy dialysis fluid | - white flecks, strands or clumps (fibrin) in the dialysis fluid

Question 50

What is the treatment of secondary peritonitis?

Answer 50

1. Empiric Antibiotics: Co-Amoxiclav/Piperacillin-Tazobactam + Gentamicin 2. Source Control: drainage of abscesses, appendicectomy, bowel resection, repair perforated ulcer etc.