Anaerobic Bacteria

Question 1

The Types of Anaerobic Bacteria

Answer 1

Obligate anaerobes(strict, can’t survive in 0.5% O2) e.g clostridium haemolyticum and novyi

Moderate obligate anaerobes( can survive but not replicate) e.g b.fragilis, f. Nucleatum, and some clostridia

Aerotolerant anaerobes(limited growth) e.g clostridium histolyticum

Facultative anaerobes( presence or absence of air, fermentation and oxidative phosphorylation) e.g Staph aureus and E.coli

Microaerophilic bacteria( minimal growth in anaerobic condition) e.g campylobacter jejuni

Question 2

Reasons for being anaerobic

Answer 2

Lack certain enzymes( superoxide dismutase & catalase)
Oxidation- reduction potential
Oxidative phosphorylation

Question 3

Classifications of Anaerobic bacteria

Answer 3

Gram neg bacilli e.g bacteroides spp, fusobacterium spp, prevotella spp, porphyromonas spp

Gram pos bacilli e.g clostridim spp, c.tetani, perfringes, botulinum, difficile, novyi

Gram pos cocci e.g peptococcus spp, peptostreptococcus spp

Gram neg cocci e.g veillonella spp

Question 4

Anaerobic bacteria are studied because & Found in the body as

Answer 4

They’re normal flora
Antimicrobial resistant
Diverse antibiotic therapy
Morbidity

Abscesses
Polymicrobial
Necrotizing infections

Question 5

High index of suspicion & How anaerobic bacteria establishes

Answer 5

Gas( crepitus)
Odour
No response after using antibiotics fir facultative anaerobes 
No growth in aerobic media
Sulfur granules
Necrotic tissue

Compromised vascular supply
Trauma with tissue destruction 
Normal flora displacement 
Breech in mucocutaneous barrier
Antecedent infections ( gullain barr syndrome)

Question 6

Characteristics of Bacteroides spp

Answer 6

Gram neg bacilli
Bile resistant and non pigmented
Infectious below the diaphragm
Virulence factors: capsular polysaccharides
Resistant to beta lactam antibiotics ( penicillins and cephalosporins)
Media: Bacteroids bile aesculin agar

Question 7

Characteristics of fusobacterium spp

Answer 7

Gram neg bacilli
Inhabits upper respiratory tract and GIT
Most common- f.nucleatum
Most virulent- f.necrophorum( pharyngotonsilitis)
Tropical ulcer- f.ulcerans

Occasionally in puerperal sepsis and septic abortion

Question 8

Characteristics of clostridium spp

Answer 8

Over 100 spp
Gram pos bacilli, spore forming
Catalase positive 
Ubiquitous in nature
Motile by flagella 
Disease due to elaboration of highly effective exotoxins 

4 types