Classification of bacteria

Classification of bacteria

1. Gram Positive

   • Coccus
     • Catalase positive = Staphylococcus
       • Coagulase positive = S. aureus skin and soft tissue, endocarditis, toxin mediated disease. Mx flucloxacillin or erythromycin. MRSA Mx - vancomycin or linezolid
       • Coag neg - staph skin commencal. Prosthetic valve endocarditis. Mx - flucloxacillin or nitrofurantoin.
     • Catalase negative = Streptococcus
       • Non-haemolytic
         • Enterococcus spp GI and GU commensal. UTI, endocarditis. Mx - amoxicillin or vanc
       • Alpha-haemolytic
         • Strep pneumoniae Pharyngeal commencal, CAP, meningitis, vaccine avaliable. Mx - benzyl pen or amoxicillin.
         • Viridans strep Phryngeal commencals, native valve endocarditis. Mx - benzyl pen with gent
       • Beta haemolytic
         • Group A: Strep pyogenes Pharyngitis, nec fasciitis, rheumatic fever, scarlet fever. Mx penicillin, benzyl pen, amoxicillin
         • Group B: Strep agalactiae UTI, neonatal sepsis and meningitis. Mx- same as group A
   • Bacillus
     • Aerobic
       • Bacillus spp
         • B anthracis - anthrax, toxins (edema factor, protective entigen and lethal factor). Mx - ben pen or ciprofloxacin
         • B cerus - emetic food poisoning from rice. Self-limiting.
       • Corynebacterium diptheria some toxigenic, has vaccine. Mx - antitoxin, pen or erythromycin
       • Listeria - beta-haemolytic listeriosis (food poisoning), meningitis. Mx - amoxicillin and gent
     • Anaerobic
       • Clostridium
         • C difficile - Ab related diarrhoea, psudomembranous colitis. Mx metronidazole or vanc
         • C botulinum - food or IVDU borne botulism. Mx - anti=toxin, ben pen or metronidazole
         • C perfringens - food poisoning (self-limiting) gas gangrene Mx - ben pen or metronidazole
         • C tetani - tetanus. Mx - vaccine, metronidazole +- HTIG
       • Propionibacterium Skin commencal, acne. Mx - tetracyclines

2. Gram negative

   • Coccus = Neisseria
     • N Meningitidis 'meningococcus' meningitis and scepticaemia, notifiable disease. Mx - ben pen or ceftriaxone. Rifampicin to contacts +- vaccine
     • N gonorrhoea ' gnococcus' - STI, opthalmia neonatorum. High rates of resistance. Mx - depends on sensitivity pattern, pen and mox.
   • Coccobacillus
     • Haemophilus influenzae - polysaccharide capsule, meningitis and epiglottitis, Hib vaccine. Non-capsular strains cause ottitis media, sinusitis, COPD exacerbation. Mx co-amoxiclav or cefuroxime, amoxicillin for meningitis.
     • Bordetella pertussis - whooping cough, vaccine. Grow from nasal swabs on Bordet-Gengou agar. Mx - erythromycin
   • Bacillus
     • Glucose fermenters
       • Lactose fermentors
         • Escherichia coli - GU/GI commensal. Increasing ESBL, HUS caused by 0157, neonatal meningitis. Mx - co-amixiclav or trimethoprim.
         • Klebsiella pneumoniae - GI commensal, UTI and LRTI, amox resistant, increasing ESBL. Mx - co-amoxiclav or ciprofloxacin.
       • Non-lactose fermentor
         • Salmonella spp - food bourne, d+v, usually self-limiting. S. typhi and paratyphi cause bacteraemia. Mx - amox, trimethoprim or cipro.
     • Glucose non-fementers
       • Pseudomonas aeruginosa - HCAI, chronic colonisation in CF. Mx - ciprofloxacin or gent.
   • Spiral
     • Helicobacter pylori - strongly urease positive (C breath test), gastric ulcer disease and cancer. Mx - PPI, clarithromycin and amox or metronidazole
     • Campylobacter spp - food borne illness, bloody diarrhoea, usually self-limiting. Erythro or cipro if required
     • Vibro cholera - food/water borne, watery diarrhoea caused by cholera toxin. Mx - hydration and tetracycline