Isolation and antimicrobial susceptibilities of Chlamydial isolates from Western barred bandicoots

Abstract

A range of species of Chlamydiales have previously been detected in a variety of Australian marsupials, including koalas and western barred bandicoots. Thirty-seven ocular, urogenital, or nasal swabs were obtained from 21 wild western barred bandicoots. Chlamydia culture and antibiotic susceptibility testing were performed for cycloheximide-treated HEp-2 cells in 96-well microtiter plates. Chlamydia spp. were isolated from 11 specimens from 9 (42.8%) bandicoots. All isolates were identified as Chlamydiales by conventional PCR with 16S and 23S rRNA gene primers specific to Chlamydiales and were confirmed to be Chlamydia pneumoniae by a C. pneumoniae-specific ompA-based real-time PCR assay and 16S rRNA and 23S rRNA gene signature sequence analyses. The MICs of azithromycin, doxycycline, ciprofloxacin, and enrofloxacin for 10 C. pneumoniae isolates from these bandicoots ranged from 0.015 to 1 microg/ml, 0.25 to 1 microg/ml, 0.25 to 2 microg/ml, and 0.25 to 0.5 microg/ml, respectively. The MICs at which 90% of isolates were inhibited and the minimal bactericidal concentrations were within the ranges reported previously for human isolates of C. pneumoniae.

FIG. 1.

Photomicrograph of a bandicoot C. pneumoniae isolate showing characteristic chlamydial inclusions in HEp-2 cell culture. Magnification, ×200.