Clarithromycin-induced alterations in vaginal flora

GrgA as a potential target of selective antichlamydials

Chlamydia is a common pathogen that can causes serious complications in the reproductive system and eyes. Lack of vaccine and other effective prophylactic measures coupled with the largely asymptomatic nature and unrare clinical treatment failure calls for development of new antichlamydials, particularly selective antichlamydials without adverse effects on humans and the beneficial microbiota. We previously reported that benzal-N-acylhydrazones (BAH) can inhibit chlamydiae without detectable adverse effects on host cells and beneficial lactobacilli that dominate the human vaginal microbiota among reproductive-age women. However, the antichlamydial mechanism of BAH is not known. Whereas 4 single nucleotide polymorphisms (i.e., SNP1-4) were identified in a rare Chlamydia variant with a low level of BAH resistance, termed MCR, previous studies failed to establish a causal effect of any particular SNP(s). In the present work, we performed recombination to segregate the four SNPs. Susceptibility tests indicate that the R51G GrgA allele is both necessary and sufficient for the low level of BAH resistance. Thus, the Chlamydia-specific transcription factor GrgA either is a direct target of BAH or regulates BAH susceptibility. We further confirm an extremely low rate of BAH resistance in Chlamydia. Our findings warrant exploration of GrgA as a therapeutic and prophylactic target for chlamydial infections.

The presence of vaginal Lactobacillus species does not contribute to a measureable difference in amniotic fluid lactate levels collected from the vaginal tract of laboring women

INTRODUCTION

Amniotic fluid lactate research is based on the hypothesis that a relationship exists between fatigued uterine muscles and raised concentrations of the metabolite lactate, which is excreted into the amniotic fluid during labor. To assess potentially confounding effects of lactate-producing organisms on amniotic fluid lactate measurements, we aimed to determine if the presence of vaginal Lactobacillus species was associated with elevated levels of amniotic fluid lactate, measured from the vaginal tract of women in labor.

MATERIAL AND METHODS

Results from this study contribute to a large prospective longitudinal study of amniotic fluid lactate at a teaching hospital in Sydney, Australia. Amniotic fluid lactate measurement was assessed at the time of routine vaginal examination, after membranes had ruptured, using a hand-held lactate meter StatStripXPress (Nova Biomedical). Vaginal swab samples were collected at the time of the first amniotic fluid lactate measurement and stored for later detection and quantification of Lactobacillus species using a TaqMan real-time PCR assay. Swab sample and amniotic fluid lactate results were paired and analyzed.

RESULTS

The PCR assay detected Lactobacillus species in 48 of 388 (12%) vaginal swab specimens (8% positive, 4% low positive) collected from women in labor after membranes had ruptured. There was no significant difference in median and mean (respectively) amniotic fluid lactate levels with (8.35 mmol/L; 8.95 mmol/L) or without (8.5 mmol/L; 9.08 mmol/L) Lactobacillus species detected.

CONCLUSION

There was no association between the presence or level of vaginal Lactobacillus species and the measurement of amniotic fluid lactate collected from the vaginal tract of women during labor.

Bacteriophage and their potential roles in the human oral cavity

The human oral cavity provides the perfect portal of entry for viruses and bacteria in the environment to access new hosts. Hence, the oral cavity is one of the most densely populated habitats of the human body containing some 6 billion bacteria and potentially 35 times that many viruses. The role of these viral communities remains unclear; however, many are bacteriophage that may have active roles in shaping the ecology of oral bacterial communities. Other implications for the presence of such vast oral phage communities include accelerating the molecular diversity of their bacterial hosts as both host and phage mutate to gain evolutionary advantages. Additional roles include the acquisitions of new gene functions through lysogenic conversions that may provide selective advantages to host bacteria in response to antibiotics or other types of disturbances, and protection of the human host from invading pathogens by binding to and preventing pathogens from crossing oral mucosal barriers. Recent evidence suggests that phage may be more involved in periodontal diseases than were previously thought, as their compositions in the subgingival crevice in moderate to severe periodontitis are known to be significantly altered. However, it is unclear to what extent they contribute to dysbiosis or the transition of the microbial community into a state promoting oral disease. Bacteriophage communities are distinct in saliva compared to sub- and supragingival areas, suggesting that different oral biogeographic niches have unique phage ecology shaping their bacterial biota. In this review, we summarize what is known about phage communities in the oral cavity, the possible contributions of phage in shaping oral bacterial ecology, and the risks to public health oral phage may pose through their potential to spread antibiotic resistance gene functions to close contacts.

Identification of yeasts in public hospital primary care patients with or without clinical vaginitis

OBJECTIVE

Vaginal yeast infections are one of the most common female genital tract infections. Candida albicans is the most common infectious cause. Candida species other than C. albicans are being diagnosed with increasing frequency. The aim of the present study was to determine species of yeasts obtained from the vaginal fluid among public hospital primary care patients with or without clinical vaginitis and to evaluate the correlation of vaginal yeast colonisation with epidemiological and clinical features of applicants.

METHODS

Vaginal swabs from 622 women who underwent vaginal examination in a women's hospital were obtained. After isolation, identification tests were carried out on 106 yeast species. Epidemiological and clinical features of women with respect to these species were evaluated.

RESULTS

Of 106 yeasts isolated, 67 C. albicans, 10 C. glabrata, seven C. kefyr (pseudotropicalis), six C. tropicalis, five C. parapsilosis, five C. krusei, three Saccharomyces boulardii, one C. guillermondii, one S. cerevisiae and one Trichosporon species were identified as yeast subtypes. Of the women with C. albicans, C. glabrata, C. kefyr, C. tropicalis, C. krusei, 60, three, one, one, and one, respectively, had symptoms of vaginitis. Of women with C. albicans, C. glabrata, C. kefyr, C. tropicalis, C. parapsilosis, C. krusei, and the other species, 27, four, three, two, one, one, and one, respectively, had clinical findings of vaginitis.

CONCLUSION

Despite the heterogeneity of the present study group, the results support the use of vaginal culture as the most sensitive test for final diagnosis. However, a positive culture does not mean that the C. albicans is pathogenic, as it may be the normal commensal pathogen. Correlation of clinical and laboratory findings is important as it enables the administration of appropriate treatment without delay.