Repeat infections of chlamydia are very common and may represent a new infection, re-infection from an untreated partner or treatment failure. The aim of this cohort study is to estimate the proportion of women infected with chlamydia who experience failure after treatment with 1 gram azithromycin.
Methods
Women diagnosed with chlamydia were followed for 8 weeks post treatment with 1 gram azithromycin and provided weekly genital specimens for further assay. The primary outcome was the proportion of women classified as having treatment failure at least 4 weeks after recruitment. Comprehensive sexual behaviour data collection and the detection of Y chromosome DNA in vaginal swabs and genome sequencing were used to differentiate between chlamydia re-infection and treatment failure. Chlamydia culture and MIC was also undertaken.
Results
There were 305 women recruited with a response rate of 66%. A total of 36 women were diagnosed with repeat chlamydia infection during follow up (11.8%; 95% CI: 8.4%, 16.0%). The median time till repeat infection was 7 weeks, with 25% of repeat infections diagnosed within 5 weeks. The risk of repeat infection increased with increasing organism load of initial infection (OR = 1.6; 95% CI: 1.2, 2.8 for each additional log increase in load). Of the 36 women with repeat infection, 16 (44.4%; 95% CI: 27.9%, 61.9%) were classified as treatment failure with an overall risk of treatment failure of 5.2% (95% CI: 3.0%, 8.4%). There was no detectable shift in MIC between initial and repeat infections with MIC within reported antimicrobial susceptibility ranges.
Conclusion
Using a combination of advanced laboratory techniques and comprehensive sexual behaviour data, we estimate that about 1 in 20 women with chlamydia infection treated with 1 gram of azithromycin will fail treatment. Further laboratory investigation will determine whether there are any genomic characteristics of the infections associated with treatment failure in our cohort.
Chlamydia trachomatis infects the urogenital tract (UGT) and eyes. Anatomical tropism is correlated with variation in the major outer membrane protein encoded by ompA. Strains possessing the ocular ompA variants A, B, Ba and C are typically found within the phylogenetically coherent "classical ocular lineage". However, variants B, Ba and C have also been found within three distinct strains in Australia, all associated with ocular disease in children and outside the classical ocular lineage. CtGEM genotyping is a method for detecting and discriminating ocular strains and also the major phylogenetic lineages. The rationale was facilitation of surveillance to inform responses to C. trachomatis detection in UGT specimens from young children. CtGEM typing is based on high resolution melting analysis (HRMA) of two PCR amplified fragments with high combinatorial resolving power, as defined by computerised comparison of 65 whole genomes. One fragment is from the hypothetical gene defined by Jali-1891 in the C. trachomatis B_Jali20 genome, while the other is from ompA. Twenty combinatorial CtGEM types have been shown to exist, and these encompass unique genotypes for all known ocular strains, and also delineate the TI and T2 major phylogenetic lineages, identify LGV strains and provide additional resolution beyond this. CtGEM typing and Sanger sequencing were compared with 42 C. trachomatis positive clinical specimens, and there were no disjunctions. CtGEM typing is a highly efficient method designed and tested using large scale comparative genomics. It divides C. trachomatis into clinically and biologically meaningful groups, and may have broad application in surveillance.
The Australian northern quoll is an important predatory marsupial carnivore that is currently endangered due to inappropriate fire regimes, predation, and the spread of invasive cane toads. The microbiota of Australian marsupials has not been extensively studied, but is thought to play a role in their health. This study provides an initial characterization of the cloacal microbiota of the northern quoll, as well as other marsupials including possums and kangaroos which were opportunistically sampled. The northern quoll cloaca microbiota was dominated by Enterococcus and Lactobacillus and had a relatively high proportion of members of the Proteobacteria phylum, which has been observed in other carnivorous marsupials. The diversity and structure of the microbiota was not influenced by presence of Chlamydiales which are intracellular bacteria and potential pathogens. The microbiota of the other marsupials was quite varied, which may be related to their health status. Characterization of the northern quoll microbiota will help to better understand the biology of this endangered animal.
ABSTRACT Lactococcus lactis is a gram-positive bacterium that is widely used in the food industry and is therefore desirable as a candidate for the production and secretion of recombinant proteins. Previously, we generated a L. lactis strain that expressed and secreted the antimicrobial cell wall-lytic enzyme lysostaphin. To identify lactococcal gene products that affect the production of lysostaphin, we isolated and characterized mutants generated by random transposon mutagenesis that had altered lysostaphin activity. Out of 35,000 mutants screened, only one with no lysostaphin activity was identified, and it was found to contain an insertion in the lysostaphin expression cassette. Ten mutants with higher lysostaphin activity contained insertions in only four different genes, which encode an uncharacterized putative transmembrane protein (llmg_0609) (three mutants), an enzyme catalyzing the first step in peptidoglycan biosynthesis ( murA2 ) (five mutants), a putative regulator of peptidoglycan modification ( trmA ) (one mutant), and an uncharacterized enzyme possibly involved in ubiquinone biosynthesis (llmg_2148) (one mutant). These mutants were found to secrete larger amounts of lysostaphin than the control strain (MG1363[ lss ]), and the greatest increase in secretion was 9.8- to 16.1-fold, for the llmg_0609 mutants. The lysostaphin-oversecreting llmg_0609, murA2 , and trmA mutants were also found to secrete larger amounts of another cell wall-lytic enzyme (the Listeria monocytogenes bacteriophage endolysin Ply511) than the control strain, indicating that the phenotype is not limited to lysostaphin.
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