Bacteria Classification

Question 1

How are gram positive bacteria identified?

Answer 1

Stain purple

Question 2

Classification of GRAM positive (aerobic)

Answer 2

Coccii: chains (streptococti) - apha-haemolytic, beta-haemolytic, non-haemolytic
Clusters (staphylococci) - coagulate positive/negative

Bacilli: small - corynebacterium spp., listeria spp.
Large - bacillus spp.

Question 3

Classification of GRAM positive (anaerobic)

Answer 3

Cocci - anaerobic streptococci
Bacilli (grow in absence of oxygen) - clostridium spp.

Question 4

Staphylococci - coagulase positives

Answer 4

• clusters
• major human pathogen
• staphylococcus aureus: mssa+ mrsa
• Red, inflamed, warm to touch, pus
• penicillin resistant due to production of penicillinase

Question 5

Staphylococci-coagulase negative

Answer 5

• S. Epidermis
• form biofilms

Question 6

Streptococci

Answer 6

• Alpha-haemolytic (partial haemolysis) - turn blood agar green =pneumonia, meningitis, infective endocarditis
• beta-haemolytic (complete haemolysis) - turn blood agar clear = surface antigens A-G, ABFG clinically most important
• non haemolytic - no difference

Question 7

Bacilli - clostridiodes difficult

Answer 7

• Difficult to culture
• spread via spores
• asymptomatic gut carriage

Question 8

Gram negative

Answer 8

• Ghonneria
• tuberculosis
• can cause meningitis
• salmonella,
• campylobacter
• E. coli

Question 9

Miscellaneous

Answer 9

• leprosy
• syphilis
• Lyme disease spread by ticks