clinically important bacteria

clinical classification of bacteria

mainly belong to Enterobacteriaceae family & are non-fastidious, facultative anaerobes with fermentative metabolism, oxidase negative, bile tolerant, & if motile then have peritrichous flagella
obligate anaerobes:
- bacteroidaceae (non-sporing)
- bacteroides (mixed acid f. glucose)
- fusobacterium (butyric acid mainly f. glucose)
- leptotrichia (lactic acid mainly f. glucose)
facultative anaerobes:
- oxidase negative:
  - enterobacteriaceae (ferm., non-fastidious)
    - Escherichia (acid f.lactose)
    - Edwardsiella
    - Citrobacter (acid f.lactose)
    - Salmonella (ONPG neg, urea neg; mannitol→gas)
    - Shigella (ONPG neg, urea neg; mannitol→no gas)
    - Klebsiella (acid f. lactose)
    - Enterobacter (acid f. lactose)
    - Serratia
    - Proteus (ONPG neg. urea pos.)
    - Providencia
    - Yersinia including bubonic plague and Yersiniosis (ONPG pos.)
    - Erwinia
    - actinobacillus (ferm., pleomorphic fastidious)
- oxidase positive:
  - fermentative:
    - Vibrio
    - Aeromonas
    - Pasteurella
    - Plesiomonas
oxidative
- Flavobacterium (variably fac.anaer.)
obligate aerobes:
- Pseudomonas (oxidase +ve, not ferment.)
- Xanthomonas
- Alcaligenes (oxidase +ve, alkali producing)
fastidious
- Legionella (Legionaire's disease)

facultative anaerobes
- Haemophilus (fastid.,)
obligate aerobes
- Brucella (fastid. needs vitamins)
- Bordetella (complex media with nicotinic acid)
- Francisella (highly fastid.)

obligate aerobes
- Neisseria (bean-shaped diplococci, fastid., oxidase +ve)
  - N. gonorrhoeae (gonococcus)
  - N. meningitidis (meningococcus)
- Acinetobacter
- Moraxella (oxidase +ve)
- Branhamella (oxidase +ve)
anaerobes
- Veillonella (oxidase neg., fastid.)
intracellular
- Rickettsia
- Coxsiella
- Chlamydia

sporing:
- Bacilli (aerobic)
- Bacillus anthracis (anthrax)
- Clostridium (anaerobic with variable O2 tolerance)
  - see also tetanus, Clostridium difficile
non-sporing:
- Lactobacilli
- Listeria
- Erysipelothrix
coryneform & filamentous:
- Corynebacterium
- Propionibacterium
- Actinomyces
- Nocardia
mycobacteria (not really Gram +ve)
- tuberculosis (TB)
Streptomyces

catalase +ve
- Micrococcaceae
- staphylococcus (fermentative)
  - Staph. aureus
- Micrococcus (oxidative)
catalase -ve
- Streptococcaceae (fac. anaerobes, pairs or chains)
- streptococcus / streptococcal infections
  - Str. pyogenes
  - Str. pneumoniae pneumococcus
- Enterococcus including VRE Enterococcus faecalis formerly known as Str. faecalis
- Peptococcaceae (oblig. anaerobes)
- Peptococcus (no chains usually)
- Peptostreptococcus (pairs or chains)
- Parvimonas infections

Mycoplasmataceae
- Mycoplasma (need sterols, most fac.anaer.)
- Acholeplasma (do not need sterols)
- Ureaplasma (hydrolyse urea, need urea & sterols)
L forms of Classical bacteria (require hypertonicity)
- NB. induced by antibiotics/lysozyme/Ab-C/osmotic/etc.
- Need phase contrast or Giemsa stain;
- stable L-forms (wholly cell wall defic. abn. form)
  - not able to revert;
- unstable L forms (partly defic. cell wall abn. form)
  - revert to normal form of bacteria if inducing factor withdrawn;

Include:
- pyogenic cocci - S.aureus; Str.pyogenes/pneumoniae; N.mening./gono.
- Gram-ve rods - E.coli; Proteus; Ps.aerug.; Bacteroides;