Table of Contents
Community-acquired pneumonia
- Streptococcus pneumoniae
- Haemophilus influenzae (if not vaccinated)
- Atypicals
If immunocompromised (e.g. malnourished, alcoholic, diabetic, on long-term steroids), also: Staphylococcus aureus, coliforms, TB
If severely immunosuppressed (e.g. HIV with CD4 <200, transplant recipient), also: Pneumocystis carinii, Cryptococcus, CMV, Varicella zoster virus, influenza, fungal infections
Hospital-acquired pneumonia
- Staphylococcus aureus (including MRSA)
- Anaerobes
- Coliforms
- Pseudomonas
Colonising bacteria in chronic respiratory diseases (may or may not cause infections/exacerbations)
- Streptococcus pneumoniae
- Haemophilus influenzae
- Moraxella catarrhalis
- Staphylococcus aureus
- Pseudomonas
In cystic fibrosis, also: Burkholderia cepacia
Upper respiratory tract infections
- Streptococcus pneumoniae
- Streptococcus pyogenes
- Haemophilus influenzae
- Moraxella catarrhalis
Cavitating pneumonia
- Streptococcus pneumoniae
- Staphylococcus aureus
- Klebsiella
- TB
- Anaerobes
Intra-abdominal (including biliary)
Normal bowel flora:
- Anaerobes, e.g. Bacteroides
- Coliforms
- Enterococcus
Gastroenteritis/diarrhoea
→ ceftriaxone/ciprofloxacin/azithromycin
- Salmonella enteritidis
- Shigella
- Campylobacter
- Escherichia coli (enterotoxic)
Less common: Yersinia enterocolitica, Bacillus cereus, Staphylococcus aureus
If risk factors, also: Clostridium difficile, Vibrio cholerae, Salmonella typhi
If dysentery: Shigella, Vibrio cholerae, amoebiasis
Don’t forget viral, parasitic and non-infectious causes!
Skin/joints/bone
- Staphylococcus aureus
- Streptococcus pyogenes
For wound/ulcer infections or severe/necrotising cellulitis, also: anaerobes
For burns, also: anaerobes, Pseudomonas
For post-surgical wounds, also: Gram negative bacilli (e.g. E. coli, Klebsiella, Pseudomonas), Enterococci, MRSA, CONS
NB: wound-colonising bacteria (i.e. bacteria present in exudate without necessarily causing infection) include: coliforms, Enterococcus, anaerobes
Meningitis
- Neisseria meningitidis (meningococcal)
- Streptococcus pneumoniae (pneumococcal)
- Haemophilus influenzae (if not vaccinated)
- Listeria (if >65 years or immunocompromised)
If neonatal: group B Streptococcus, E. coli/coliforms, Listeria (rare)
Urine
- Escherichia coli
- Staphylococcus saprophyticus
- Non-E. Coli enterobacteriaceae (Klebsiella, Enterobacter, Proteus), Pseudomonas, Enterococci, Staphylococci (CONS/aureus)
Less common organisms (3) are associated with: catheters, hospitals, structural abnormalities and instrumentation
Infective endocarditis
- Viridans group Streptococci and other Streptococci (e.g. bovis)
- Enterococci
- Staphylococcus aureus and coagulase-negative Staphylococci (e.g. epidermidis)
- Coxiella burnetii
- HACEK organisms
Surgical prophylaxis
- Need to cover skin ± intra-abdominal organisms
Sepsis of unknown origin
- Need to cover skin, chest, urine, intra-abdominal organisms
