Genotypic profile of Streptococcus suis serotype 2 and clinical features of infection in humans, Thailand

To examine associations between clinical features of Streptococcus suis serotype 2 infections in humans in Thailand and genotypic profiles of isolates, we conducted a retrospective study during 2006–2008. Of 165 patients for whom bacterial cultures of blood, cerebrospinal fluid, or both were positive for S. suis serotype 2, the major multilocus sequence types (STs) found were ST1 (62.4%) and ST104 (25.5%); the latter is unique to Thailand. Clinical features were examined for 158 patients. Infections were sporadic; case-fatality rate for adults was 9.5%, primarily in northern Thailand. Disease incidence peaked during the rainy season. Disease was classified as meningitis (58.9%) or nonmeningitis (41.1%, and included sepsis [35.4%] and others [5.7%]). Although ST1 strains were significantly associated with the meningitis category (p<0.0001), ST104 strains were significantly associated with the nonmeningitis category (p<0.0001). The ST1 and ST104 strains are capable of causing sepsis, but only the ST1 strains commonly cause meningitis.

Impact of pandemic influenza (H1N1) virus-associated community-acquired pneumonia among adults in a tertiary hospital in Thailand

In July 2009, a pandemic influenza (H1N1) (pdm H1N1) virus epidemic emerged rapidly in Phitsanulok, Thailand. Adult cases of community-acquired pneumonia (CAP) were prospectively examined for pdm H1N1 virus infections by real-time PCR in a tertiary hospital in Phitsanulok from July to November 2009. Twenty-four cases of pdm H1N1 virus-associated CAP were confirmed, and their clinical features including bacterial infection, severity of disease, course of admission, treatment, and outcome were investigated. The median age of these cases was 39.5 years. Most cases appeared to be primary viral pneumonia, but only one case was positive for a urinary pneumococcal antigen. The median time from the onset of illness to admission was 4 days. All 24 patients received oseltamivir after admission. Twelve (50.0%) were defined as having severe CAP and 9 (37.5%) were diagnosed with acute respiratory distress syndrome (ARDS). During the study period, pdm H1N1 virus infections frequently caused severe CAP among young adults because of the delayed initiation of antiviral therapy. Of the 9 ARDS patients, 3 died of ventilator-associated pneumonia caused by multidrug-resistant Acinetobacter baumannii. Implementation of infection control targeting this pathogen is required in tertiary hospitals in Thailand.

Development of triplex SYBR green real-time PCR for detecting Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella spp. without extraction of DNA

Although Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella spp. are prevalent causes of community-acquired pneumonia, rapid and sensitive diagnosis is difficult. Real-time PCR provides rapid and sensitive diagnosis, however, DNA extraction is still required, which is time-consuming, costly and includes a risk of contamination. Therefore, we aimed to develop triplex real-time PCR without DNA extraction. AmpDirect(R) Plus which inhibits PCR inhibitors was used as the PCR buffer. Melting temperatures of the PCR products for the three bacteria were analyzed by SYBR green triplex real-time PCR and were found to be significantly different. Detection limits of bacteria cells diluted in nasopharyngeal aspirates (NPAs) were comparable with the detection limits of previously reported real-time PCR. Our PCR without DNA extraction and probe real-time PCR with DNA extraction showed identical results for the detection of the three bacteria from 38 respiratory specimens (sputum, endotracheal aspirates, and NPAs) collected from patients with pneumonia. No cross-reaction with other bacteria was observed. Our triplex real-time PCR successfully detected and differentiated the three bacteria. Although further field tests are required, our assay is a promising method for the rapid and cost-effective detection of the three bacteria.