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 g/ml, 0.25 to 1 g/ml, 0.25 to 2 g/ml, and 0.25 to 0.5 g/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.

In vitro activity of chloramphenicol, florfenicol and enrofloxacin againstChlamydia pecorumisolated from koalas (Phascolarctos cinereus)

“…The C. pecorum susceptibility to enrofloxacin in this study was the same as that of C. pneumoniae isolated from western barred bandicoots (MIC 0.25–0.5 µg/mL); C. psittaci isolated from turkeys (MIC 0.25 µg/mL); and to the susceptibility of ruminant isolates of C. pecorum to other fluoroquinolones (ofloxacin MIC 0.25–0.5 µg/mL, ciprofloxacin MIC 0.25–1.0 µg/mL) . Additionally, C. pecorum susceptibility to chloramphenicol in vitro was similar to that of C. trachomatis isolated from humans (MIC 0.25–1.0 µg/mL; MIC 1.0 µg/mL; MIC 0.5–1.0 µg/mL), despite the lack of a standardised testing procedure for chlamydial susceptibility testing.…”

Evaluation of enrofloxacin use in koalas (Phascolarctos cinereus) via population pharmacokinetics andMonteCarlo simulation

“…The in vitro susceptibility of koala isolates of C. pecorum and C. pneumoniae to enrofloxacin has not been determined. However, the MIC and minimum bactericidal concentration of enrofloxacin against C. pneumoniae isolated from another Australian marsupial, the western barred bandicoot, were both 0.25–0.5 mg/L (Kumar et al ., ), and the enrofloxacin MIC against Chlamydia psittaci isolated from turkeys was 0.25 mg/L (Butaye et al ., ). As the in vitro susceptibility of C. pecorum to antibacterials is similar across chlamydial species (Kumamoto et al ., ; Pudjiatmoko et al ., ), 0.25 mg/L was selected as the target MIC for antichlamydial dosing calculations in this study.…”

Stability ofChlamydophila pneumoniaein a harsh environment without a requirement for acanthamoebae

“…However, the route of infection from C. pneumoniae in the soil environment to humans is not easy to explain. C. pneumoniae infection has occurred in amphibians, koalas and horses; nevertheless, direct human infection from such species is unlikely (23,24,(27)(28)(29)(45)(46)(47)(48). Moreover, Bourke et al have reported a high prevalence of antibodies to C. pneumoniae in farmers in the United Kingdom (52), strongly implying that transmission may occur via a contagious source of C. pneumoniae in the natural environment.…”

“…in vitro study has revealed that the survival of C. pneumoniae is increased in the presence of amoebae (22), although actual interaction in the field between C. pneumoniae and amoebae has not as yet been demonstrated. Other hosts that are naturally infected by C. pneumoniae include koalas, horses and free-ranging frogs, indicating that this bacterium is an important pathogen, infecting not only mammals but also amphibians, and that it may be widespread in natural environments (23)(24)(25)(26)(27)(28)(29). Other chlamydia, such as Parachlamydia acanthamoebae, which belongs to the order Chlamydiales, has been discovered to be the endosymbiont of acanthamoebae from the nasal mucosa of healthy volunteers, and to possess the ability to survive in natural environments (20,(30)(31)(32)(33).…”