🦠 bacteria

Staphylococcus aureus

Gram positive cocci in clusters
facultatively anaerobic
catalase positive
coagulase positive
golden-yellow colonies (staphyloxanthin)

Staphylococcus epidermidis

Gram positive cocci in clusters
catalase positive
coagulase negative
resident skin flora
causes prosthesis-associated infections

Staphylococcus saprophyticus

Gram positive cocci in clusters
catalase positive
coagulase negative
cause acute cystitis in young women

Streptococcus
Enterococcus

Gram positive cocci in chains
aerobic, facultatively anaerobic

Peptostreptococcus
Peptococcus

Gram positive cocci in chains
anaerobic

Listeria monocytogenes

Gram positive bacilli
non-spore-forming
aerobic
foodborne, mother-to-baby transmission

Corynebacterium diphtheriae

Gram positive pleomorphic bacilli
non-spore-forming
aerobic
coryneform (characteristic swelling at end)
cause diphtheria

Corynebacterium striatum

Gram positive pleomorphic bacilli
commensal of skin & mucous membrane
opportunisitic pathogen

Bacillus anthracis

Gram positive bacilli
boxcar shaped
aerobic
single endospore
cause anthrax

Bacillus cereus

Gram positive bacilli
boxcar shaped
aerobic
single endospore
cause food poisoning, associated with indwelling catheters

Nocardia

Gram positive bacilli
beaded/branching appearance
partially acid-fast (mycolic acid)
causes suppurative granulomatous inflammation

Mycobacterium tuberculosis

Gram positive bacilli
aerobic

Clostridium tetani
Clostridium perfringens
Clostridium botulinum
Clostridium difficile

Gram positive bacilli
anaerobic
spore-forming

Neisseria gonorrhoeae

Gram negative diplococci
strictly aerobic
oxidase positive
Thayer-Martin agar
sexual transmission

Neisseria meningitidis

Gram negative diplococci
strictly aerobic
oxidase positive
capsule
transmission by droplet/mucosal contact
serogroups: A,B,C,X,Y,W-135

Enterobacteriaceae

Gram negative bacilli
facultatively anaerobic
glucose fermenter
oxidase negative
commensals in large bowel

Escherichia coli

[Enterobacteriaceae]
- diarrhoeal disease
- urinary tract infection, bacteriaemia, meningitis in neonates, peritonitis

Klebsiella pneumoniae

[Enterobacteriaceae]
- community-acquired pneumonia
- abscess formation
- intra-abdominal infections
- nosocomial infections

Salmonella enterica

[Enterobacteriaceae]
- gastroenteritis
- typhoidal slamonellae: Slamonella Typhi, Paratyphi A,B,C → systemic infection
- non-typhoidal salmonellae → disseminated/focal infections

Shigella dysenteriae
Shigella flexneri
Shigella boydii
Shigella sonnei

[Enterobacteriaceae]
- bacillary dysentery
- large intestinal inflammation
- Shiga toxin

Vibrio cholerae

curved Gram negative bacilli
oxidase positive
glucose fermenter
actively motile
cholera toxin → rice water stools

Pseudomonas aeruginosa

Gram negative bacilli
strictly aerobic
non-fermenter
oxidase positive
green pigment, fruity smell
hospital-acquired infections

Acinetobacter baumannii

Gram negative coccobacilli
strictly aerobic
non-fermenter
hospital infections, nosocomial infections

Haemophilus influenzae

Gram negative coccobacilli
strictly aerobic
non-fermenter
X factor: haemin; V factor: NAD, NADP
chocolate agar
polysaccharide capsule (type b children & infants)

Brucella melitensis
Brucella abortus
Brucella suis

Gram negative coccobacilli
zoonosis
acute & chronic infection

Bacteroides
Fusobacterium
Porphyromonas
Veillonella

Gram negative
strictly anaerobic
mixed infections, abscess formation
intra-abdominal, genital tract, head & neck infections

Mycoplasma
Ureaplasma

cell wall-deficient

Borrelia recurrentis

[Spirochete]
microaerophilic
relapsing fever

Borrelia burgdorferi

[Spirochete]
microaerophilic
Lyme disease

Leptospira interrogans

[Spirochete]
aerobic
zoonosis
Leptospirosis
infection through broken skin, mucous membranes, droplets, contact with animal

Treponema pallidum

[Spirochete]
non cultivable
syphilis (sexual transmission)
chronic infection
congenital infection

Rickettsia
Orientia
Coxiella
Chlamydia

obligate intracellular

Nutrient agar

supportive media

Blood agar

enrichment media
detects haemolysis
Streptococcus pneumoniae: alpha haemolysis

Chocolate agar

enrichment media
heating releases nutrients in blood → Haemophilus influenzae
Streptococcus pneumoniae: greenish discoloration

MacConkey agar

selective media, differential media
various enteric Gram negative bacilli
differentiates lactose fermenters & non-fermenters

Mannitol salt agar

selective media
Staphylococcus

Xylose-lysine deoxycholate (XDL) agar

selective media, differential media
Salmonella, Shigella

Thiosulphate citrate bile salts (TCBS) agar

selective media, differential media
Vibrio

Lowenstein-Jensen agar

selective media, egg-based media
Mycobacteria
malachite green to inhibit growth of other bacteria

Selenite-F broth

selective media
enrichment & selective for Salmonella

Thayer-Martin agar

selective media, enrichment media
Neisseria gonorrhoeae
additional nutrients to support growth, antimicrobials to suppress growth of normal flora

chromogenic media

distinguish different organisms by displaying color change
urine culture