Bacteria Organisms

Staph Aureus +ve

Niche	Main Infections	Other
Nose	Skin/soft tissue, bacteraemia, bone/joint, endocarditis	50% of people carry in nose

Staph Epidermidis +ve

Niche	Main Infections	Other
Skin	Prosthetic device infection	Part of normal skin flora - opportunistic

Strep pyogenes (Group A Strep) +ve

Niche	Main Infections	Other
Pharynx	Scarlet fever, sore throat, necrotising fasciitis, puerpeal sepsis	Often associated with secondary immunological presentations

Strep pneumoniae +ve

Niche	Main Infections	Other
Pharynx	Pneumonia, meningitis	Commonest bact. cause of both

C. diff. +ve

Niche	Main Infections	Other
Colon	Pseudomembranous colitis	Usually as a result of antibiotic treatment. Opportunistic

E. coli -ve

Niche	Main Infections	Other
Colon	UTIs, intra-abdo infections, sepsis, HUS	Other species of ‘coliform’ e.g. Klebsiella pneumoniae, Enterobacter cloacae, cause similar infections. Bacillus

Pseudomonas aeruginosa -ve

Niche	Main Infections	Other
Water	VAP, bacteraemia	Opportunistic bacillus - green pigment

Neisseria meningitidis -ve

Niche	Main Infections	Other
Pharynx	Meningococcal sepsis, meningitis	Reduction since vaccine. Coccus

Neisseria gonorrhoeae -ve

Niche	Main Infections	Other
No colonisation	Gonorrhoea, Ophthalmia Neonatorum	Can rarely cause invasive infections (e.g. septic arthritis). Diplococci

Chlamydia trachomatis -ve

Niche	Main Infections	Other
No colonisation	Chlamydia	Commonest STI

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Haemophilus influenzae -ve

Niche	Main Infections	Other
Pharynx	RTIs, meningitis, epiglottitis, otitis media	Capsulated types (e.g. type b) cause meningitis and epiglottitis

Mycobacterium tuberculosis AFB

Niche	Main Infections	Other
No colonisation	TB	Don’t gram stain (AFB)