Time series analysis of reported cases of hand, foot, and mouth disease from 2010 to 2013 in Wuhan, China.

BACKGROUND: Hand, foot, and mouth disease (HFMD) is an infectious disease caused by a group of enteroviruses, including Coxsackievirus A16 (CVA16) and Enterovirus A71 (EV-A71). In recent decades, Asian countries have experienced frequent and widespread HFMD outbreaks, with deaths predominantly among children. In several Asian countries, epidemics usually peak in the late spring/early summer, with a second small peak in late autumn/early winter. We investigated the possible underlying association between the seasonality of HFMD epidemics and meteorological variables, which could improve our ability to predict HFMD epidemics. METHODS: We used a time series analysis composed of a spectral analysis based on the maximum entropy method (MEM) in the frequency domain and the nonlinear least squares method in the time domain. The time series analysis was applied to three kinds of monthly time series data collected in Wuhan, China, where high-quality surveillance data for HFMD have been collected: (i) reported cases of HFMD, (ii) reported cases of EV-A71 and CVA16 detected in HFMD patients, and (iii) meteorological variables. RESULTS: In the power spectral densities for HFMD and EV-A71, the dominant spectral lines were observed at frequency positions corresponding to 1-year and 6-month cycles. The optimum least squares fitting (LSF) curves calculated for the 1-year and 6-month cycles reproduced the bimodal cycles that were clearly observed in the HFMD and EV-A71 data. The peak months on the LSF curves for the HFMD data were consistent with those for the EV-A71 data. The risk of infection was relatively high at 10 °C ≤ t < 15 °C (t, temperature [°C]) and 15 °C ≤ t < 20 °C, and peaked at 20 °C ≤ t < 25 °C. CONCLUSION: In this study, the HFMD infections occurring in Wuhan showed two seasonal peaks, in summer (June) and winter (November or December). The results obtained with a time series analysis suggest that the bimodal seasonal peaks in HFMD epidemics are attributable to EV-A71 epidemics. Our results suggest that controlling the spread of EV-A71 infections when the temperature is approximately 20-25 °C should be considered to prevent HFMD infections in Wuhan, China.

Prevalence, genetic characteristics, and antimicrobial resistance of staphylococcal isolates from oral cavity and skin surface of healthy individuals in northern Japan.

BACKGROUND: Oral cavity is an ecological niche for colonization of staphylococci, which are a major bacterial species causing community-acquired infections in humans. In this study, prevalence, and characteristics of staphylococci in oral cavity and skin of healthy individuals were investigated in northern Japan. METHODS: Saliva from oral cavity and swab from skin surface of hand were collected and cultured on selective media. Species of the isolates were identified genetically, and ST was determined for S. aureus and S. argenteus. Genes associated with antimicrobial resistance were detected by PCR. RESULTS: Among 166 participants, a total of 75 S. aureus isolates were obtained from 61 individuals (37 %), and recovered more frequently in oral cavity (n = 48) than skin (n = 27). Among 23 STs identified in S. aureus isolates, ST8 (CC8), ST15 (CC15), and ST188 (CC1) were the most common (10 isolates each), with STs of CC1 being dominant (17 isolates). Methicillin-resistant S. aureus (MRSA) was isolated in the skin of two individuals and belonged to ST1 and ST6. Resistance to erythromycin and gentamicin associated with erm(A) and aac(6')-Ie-aph(2")-Ia, respectively, was more commonly found in ST5 and ST8 isolates. One S. argenteus isolate (ST2250, mecA-negative) was recovered from oral cavity of a participant (0.6 %). A total of 186 isolates of coagulase-negative staphylococci (CoNS) were recovered from 102 participants and identified into 14 species, with S. warneri being the most common (n = 52), followed by S. capitis (n = 42), S. saprophyticus (n = 20) and S. haemolyticus (n = 19). mecA was detected in S. saprophyticus, S. haemolyticus, and S. caprae, while arginine-catabolic mobile element (ACME) in only S. capitis and S. epidermidis. CONCLUSION: S. aureus was more prevalent in oral cavity than skin surface, belonging to three major STs, with CC1 being a dominant lineage. The prevalence of antimicrobial resistance was distinct depending on CoNS species.

Antimicrobial Resistance and Molecular Epidemiological Characteristics of Methicillin-Resistant and Susceptible Staphylococcal Isolates from Oral Cavity of Dental Patients and Staff in Northern Japan.

The acquisition of drug resistance and virulence by staphylococcal species colonizing humans is a growing public health concern. The present study was conducted to investigate the prevalence, antimicrobial resistance and genetic characteristics of Staphylococcus isolates from the oral cavity and skin (hand) of systemically healthy subjects with dental disease and dental staff in northern Japan. Among a total of 133 subjects (91 patients and 42 staff), 87 coagulase-positive Staphylococcus (83 S. aureus/4 S. argenteus) and 162 coagulase-negative Staphylococcus (CoNS) isolates were recovered from 59 (44.4%) and 95 (71.4%) subjects, respectively. Three oral isolates were methicillin-resistant S. aureus (MRSA) (3.6%, 3/83) that were genotyped as ST8-SCCmec-IVl, ST4775(CC1)-SCCmec-IVa and ST6562(CC8)-SCCmec-IVa. Remarkably, the ST6562 isolate harbored PVL genes on ΦSa2usa and type I ACME (arginine catabolic mobile element). Four methicillin-susceptible isolates were identified as S. argenteus belonging to ST1223 and ST2250, which harbored enterotoxin genes egc-2 and sey, respectively. Among the fourteen CoNS species identified, methicillin-resistant (MR) isolates were detected in five species (11 isolates, 13.3% of CoNS), with S. saprophyticus and S. haemolyticus being the most common. ACME was prevalent in only S. epidermidis and S. capitis. These findings indicated the potential distribution of USA300 clone-like MRSA, toxigenic S. argenteus and MR-CoNS in the oral cavity of dental patients.