Bacterial diversity and prevalence of antibiotic resistance genes in the oral microbiome.

OBJECTIVES: This study aims to describe the oral microbiome diversity and prevalence of ARGs in periodontal health and disease. BACKGROUND: The human oral cavity harbors a complex microbial community known as the oral microbiome. These organisms are regularly exposed to selective pressures, such as the usage of antibiotics, which drive evolution and acquisition of antibiotic resistance genes (ARGs). Resistance among oral bacteria jeopardizes not only antibiotic therapy for oral infections, but also extra-oral infections caused by bacterial translocation. METHODS: We carried out a cross-sectional investigation. Saliva and subgingival plaque samples were collected during a clinical exam. 16S rRNA gene sequencing was performed to assess microbial diversity. Resistance genes were identified through PCR assays. RESULTS: Of the 110 participants, only 22.7% had healthy periodontium, while the majority was diagnosed with gingivitis (55.4%) and chronic periodontitis (21.8%). The composition of the oral microbiota differed from healthy and diseased samples, being Streptococcus spp. and Rothia spp. predominant in periodontal disease. Regarding ARGs, 80 (72.7%) samples were positive for at least one of genes screened, erm being the most frequent variant (58.2%), followed by blaTEM (16.4%), mecA (2.7%), pbp2b and aac(6 ') (1.8%). Neither genes coding resistance to carbapenems nor metronidazole were detected. CONCLUSIONS: Our findings indicate that there are no significant differences in terms of taxonomic enrichment between healthy and diseased oral microbiomes. However, samples retrieved from healthy patients had a more diverse microbial community, whereas diseased samples have lower taxonomic diversity. We have also identified clinically relevant ARGs, providing baseline information to guide antibiotic prescription in dentistry.

HCV genotype determination in monoinfected and HIV co-infected patients in Cuba.

With the aim to characterize the HCV genotype distribution in Cuba, sera were collected from two subgroups: HCV-monoinfected and HCV/HIV co-infected patients. A combination of reverse transcription-PCR using genotype-specific primers, restriction fragment length polymorphism and sequencing was used to determine the genotype of 84 samples. Seventy-nine (94%) showed single infections (10 [12%] were genotype 1a and 69 [82%] genotype 1b) and 5 (6%) samples corresponded to mixed infections (2 [2%] with genotypes 1a/3a and 1 sample [1%] each with 1b/3a, 1b/4a and 1a/1b/3a). HCV/HIV co-infected subjects had a higher frequency of mixed infections (p=0.08), infection with genotype 3a (p=0.18) and for the first time genotype 4a was found. There was no association of any demographic characteristics with any specific genotype although HCV/HIV co-infected patients showed a tendency to have mixed genotypes in those older than 45 years of age (p=0.11). Phylogenetic analysis showed that HCV isolates clustered with subtypes 1b (n=15, maximal genetic distance 2.51%) and 1a (n=2, maximal genetic distance 0.35%). This report presents the prevalence of HCV genotypes in monoinfected and HIV co-infected patients, mixed HCV infections in HCV/HIV co-infected men who have sex with men with high-risk sexual practices and for the first time identifies that the uncommon genotype 4a can be present in a patient co-infected with HIV.

Genotypic distribution of hepatitis B virus in the Czech Republic: a possible association with modes of transmission and clinical outcome.

OBJECTIVE: The relationship between hepatitis B virus (HBV) genotype with disease or treatment outcome is beginning to be characterized. However, the link between genotype and disease transmission route has not been closely examined. We addressed this question in high-risk populations in Prague, Czech Republic. DESIGN: Patients with HBV infection were consecutively recruited into the study at an outpatient clinic between June 2000 and March 2001. Their serum samples were analysed for HBV S gene segments by polymerase chain reaction (PCR) test. The amplified product sequences were compared to those of known HBV genotypes. Patients were evaluated for other virus co-infections, and parenteral and sexual exposure histories. RESULTS: Of 57 consecutively recruited patients with evidence of HBV infection, 45 (79%) had PCR-detectable S gene sequences. Only genotypes A (n = 33; 73%) and D (n = 12; 27%) were found. There was no difference in the development of chronic infection between the two genotypes. Of nine patients co-infected with TTV, all were infected with HBV genotype A. There was a trend towards an association between number of lifetime sex partners and genotype A but not genotype D. CONCLUSIONS: In Prague, the number of HBV genotypes appears to be limited compared to other northern European countries, suggesting that the virus has recently spread in the high-risk populations. While a large proportion of HBV infections occur in intravenous drug users, a subset of HBV genotype A may be transmitted by sexual contact. An HBV subtype may influence modes of transmission of HBV.