The laboratory diagnosis of opportunistic infections caused by uncommon bacteria in Papua New Guinea.

Flavobacterium meningosepticum, Chromobacterium violaceum and Listeria monocytogenes are opportunistic pathogens of man and are occasional but important causes of infections in neonates, infants and adults in Papua New Guinea. Mortality is high. Flavobacterium meningosepticum should be suspected when a weak indole producing oxidase positive Gram-negative bacillus producing a discrete yellow non-diffusing pigment at room temperature and showing a resistant antibiotic sensitivity pattern is isolated from the blood and/or C.S.F. of a neonate. Chromobacterium violaceum can be presumptively identified if a Gram-negative bacillus producing an intense non-diffusing violet pigment is cultured, commonly in associated with multiple abscess formation in the host. The isolation of a slender Gram-positive bacillus from C.S.F. or blood which produces catalase and acetylmethylcarbinol is consistent with Listeria monocytogenes. This organism forms discretely beta haemolytic colonies on blood agar and attacks the carbohydrates salicin and trehalose.