Penicillin resistance in laboratory isolates of Streptococcus pneumoniae, in Western Australia, 1990-1994.

Increasing frequency of penicillin resistance in Streptococcus pneumoniae has been reported worldwide. We report on clinical isolates of penicillin-resistant pneumococci (PRP) in Western Australia (WA) from 1990-1994. A retrospective survey of laboratories performing susceptibility testing, or receiving isolates referred from rural areas found resistant on oxacillin disc screening, was undertaken. Four of 11 laboratories could provide data for the five year time period inclusive. Information was provided on susceptibility to penicillin, type of specimen, date of isolation and; age, sex and race of individuals with PRP. Penicillin resistance increased from 1.3% to 9.0% over the five year period. PRP were rarely invasive. Highest age specific rates per 100,000 were found in children < 5 years (19.4) and adults > or = 60 years (5.1). Aboriginal ethnicity was associated with resistance. The increasing frequency of PRP in WA indicates the need for surveillance systems for their detection.