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Background/purpose: Staphylococcus aureus (S. aureus) causes diseases ranging from mild skin infections to invasive diseases. Carriage of S. aureus, including methicillin-resistant S. aureus (MRSA), is a significant risk factor for subsequent staphylococcal infection. Several studies discussed MRSA colonization in Taiwan, but mostly in northern Taiwan. This is the first study that estimates the prevalence of MRSA nasal colonization in healthy children and identifies the potential risk factors in central Taiwan., Methods: A total of 3144 healthy children aged 2-60 months who visited Taichung Veterans General Hospital (TCVGH) were screened for nasal S. aureus carriage from July 2005 to December 2010. Questionnaires included demographic information and potential risk factors for carriage of S. aureus were completed by parents/guardians., Results: Prevalence of MSSA and MRSA were 12.09% and 5.25%, respectively. The youngest group aged 2-6 months had the highest S. aureus carriage rate, and the carriage rate revealed a peak in summer. The nasal colonization of Streptococcus pneumoniae (S. pneumoniae) was a protective factor against S. aureus colonization. 85% of the MRSA colonizing isolates belonged to clonal complex 59/staphylococcal cassette chromosome type IV or V T , the local community clone in Taiwan., Conclusion: An increasing trend of MRSA nasal carriage rate in Taiwan had been brought forward, however, it was not observed in central Taiwan during the period of 2005-2010. We found a summer peak on both MRSA and MSSA carriages., (Copyright © 2018. Published by Elsevier B.V.)

Background: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have been increasingly reported worldwide and are associated with nasal colonization. In Taiwan, available data disclosed a similar trend. We conducted a study for the updated childhood nasal MRSA carriage., Methods: From July 2005 to December 2010, children aged between 2 months and 5 years who presented for a well-child health care visit to a medical center or from kindergarten/daycare center were invited and a nasal swab specimen was obtained for the detection of MRSA. All MRSA isolates were characterized., Results: A total of 3226 children were included and the rate of nasal MRSA carriage was 10.2%. Children aged 2-6 months and >3 years were significantly associated with MRSA carriage, while pneumococcus colonization (p = 0.033) and breastfeeding (p = 0.025) were negatively associated with MRSA carriage. Of the 330 MRSA isolates, a total of 13 pulsotypes with two major patterns (type C, 47.0% and D, 29%) were identified. Most MRSA isolates belonged to two major clones, characterized as sequence type 59 (ST59)/pulsotype C/staphylococcal cassette chromosome (SCCmec) IV/Panton-Valentine leukocidin (PVL)-negative (45.8%) and ST59/pulsotype D/SCCmec V T /PVL-positive (22.7%). Two new clones as ST 508/SCCmec IV (9.7%) and ST573/SCCmec IV (7.3%) emerged and increased markedly since 2007., Conclusion: Between 2005 and 2010, 10.2% of healthy children in northern Taiwan carried MRSA in anterior nares, with the highest carriage rate for infants aged 2-6 months. Two emerging clones, ST 508 and ST 573, were identified and the clinical significance needs further surveillance., (Copyright © 2017. Published by Elsevier B.V.)

Of 259 college students in northern Taiwan surveyed, nasal carriage rate of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) was 22.4% and 1.54%, respectively and no significant difference was found between athlete students and non-athlete students. Three of four MRSA isolates belonged to sequence type 59, the endemic community clone., (Copyright © 2017. Published by Elsevier B.V.)

Female sex hormones have been related to nasal Staphylococcus aureus carriage in healthy individuals; however, whether nasal staphylococcal carriage varies by menstrual cycle phase remains unknown.We sampled anterior nares of female healthcare workers twice per week for 6 consecutive menstrual cycles. We used mixed-effects Poisson regression models to determine whether intermittent carriage was associated with cycle phases in a given individual. We also performed recurrent event survival analysis to identify host factors linked to incident carriage status.Overall, we collected 754 nasal swabs over 89 consecutive person-cycles from 14 intermittent carriers. In 84 ovulation-defined menstrual cycles (715 swabs), the period prevalence of staphylococcal carriage was 58.7%, 63.1%, and 64.9% in the follicular, periovulatory, and luteal phases, respectively; these differences were not statistically significant after multivariable adjustment and correction for within-person correlation (adjusted relative risk [RR]-periovulatory 0.92, P: 0.30; luteal 1.00, P: 0.98).Using survival analysis, we identified several host factors that were associated with incident loss, gain of colonization, or both. For example, as compared to women aged 20 to 30 years, those aged 30 to 40 years were less likely to losing carriage (hazard ratio [HR]: 0.26, 95% confidence interval [CI]: 0.09, 0.80) but were as likely to regaining carriage (HR: 0.53, 95% CI: 0.21, 1.34). In comparison, being underweight (body mass index [BMI] <18.5) was significantly associated with a higher risk for regaining (HR: 1.95, 95% CI: 1.34, 1.51) and losing (HR: 1.57, 95% CI: 1.16, 2.12) colonization, indicating the alternating tendency for status changes. Personal hygiene behaviors, such as nostril cleansing habit and methods, differentially affected carriers' risk for losing or regaining staphylococcal colonization.Using an intensive sampling scheme, we found that nasal staphylococcal carriage could vary substantially over time in healthy carriers. Yet, such dynamic intraperson changes in carriage status did not depend on menstrual cycle phases but were associated with host age, BMI, and personal hygiene behavior.

Background: Most reported studies of methicillin-resistant Staphylococcus aureus (MRSA) carriage have represented 1 time point. To better understand dynamic changes of nasal MRSA carriage, we conducted this longitudinal study in Taiwan., Methods: We recruited 304 newborn babies and obtained samples from nares for detection of S. aureus within 3 days of life, and obtained further samples periodically up to 2 years of age. A total of 12 samplings were attempted to be obtained., Results: Totally, 273 subjects with ≥9 samples were included for analysis. One hundred and ten subjects (40%) harbored MRSA, on one or more occasions; of these 82 (75%) had ≥2 positive specimens and 84 (76%) had colonization ≤4 months of age. Fourteen infants (5.1%) carried MRSA within 3 days of life, the rate peaked at the age of 2 months (21%) and it was lowest (3.1%) at the age of 18 months. All but 4 first MRSA isolates from the colonized subjects carried either staphylococcal cassette chromosome (SCCmec) IV or V(T). Of 32 subjects with ≥4 MRSA isolates, all isolates from the same subject were genetically indistinguishable in 17 (53%) and genetically related in an additional 9 (28%). Five episodes of skin and soft tissue infections (SSTIs) were identified in 4 subjects., Conclusion: In Taiwan, during the first 2 years of life, two-fifths of the children ever harbored MRSA, whereas fewer than 2% of them had SSTIs. Three-fourths of the colonization occurred within the first 4 months and were persistent. More than half of the persistent colonizing isolates were genetically indistinguishable.

To determine the long-term carriage patterns, strain relatedness, and incidence of subsequent infections among methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) carriers, we screened 154 high school students for nasal carriage of S. aureus on 8 occasions over 11 months. Persistent carriage was defined as a positive culture on ≥7 occasions. Two consecutive isolates from the same subject comprised a pair, and strain relatedness was determined for each pair by molecular typing. Of 1,232 nasal swab cultures obtained on 8 occasions, 323 (26.2%) were positive for S. aureus. Forty-five isolates (3.7%) were MRSA and 278 isolates (22.6%) were MSSA from 12 and 63 subjects, respectively. Thirty-five (77.8%) MRSA isolates harbored a type IV or VT staphylococcal chromosomal cassette mec element. Among the 154 subjects, 52 (33.8%) were intermittent (1 to 6 positive swabs) carriers. Persistent carriage was identified in 23 (14.9%) subjects, and the incidence was not significantly different for MRSA and MSSA carriers (3/12 [25%] versus 20/63 [31.7%]; P=0.7449). The MRSA and MSSA isolates were composed of 33 and 215 strain pairs, respectively. Of them, an indistinguishable genotype was identified in 33 (100%) MRSA pairs and 173 (80.5%) MSSA pairs (P=0.0053). Five subjects developed cellulitis, and the incidence of this was higher for MRSA carriers (2/12 [16.7%]) than for MSSA carriers (1/63 [1.58%]; P=0.0632) and noncarriers (2/79 [2.56%]; P=0.0828). In conclusion, the long-term carriage patterns for MRSA and MSSA in healthy individuals were similar. MRSA carriers were more likely to carry a single strain, with a trend toward a higher chance of developing cellulitis than for MSSA carriers.

Background: The aim of the study was to investigate whether the 7-valent pneumococcal conjugate vaccine (PCV7) alters common risk factors of nasopharyngeal carriage by Streptococcus pneumoniae in children., Methods: From July 2005 through December 2010, we performed a cross-sectional study investigating risk factors associated with pneumococcal carriage in children. Parents of participating children completed questionnaires including whether or not the children received PCV7 vaccination., Results: Among 9705 children, 20.2% of them received at least 1 dose of the PCV7 vaccine. Multivariate logistic regression models identified older age, having 1 sibling in a family, history of acute otitis media and household exposure to smoking as independent risk factors for pneumococcal carriage in the unvaccinated group, but not associated with pneumococcal carriage in the vaccinated group. The number of siblings ≥2 in a family, history of upper respiratory tract infection and child-care attendance were strong factors associated with pneumococcal carriage in children, regardless of vaccination. In vaccinated group, breast-feeding was associated with increased nonvaccine type pneumococcal carriage, mainly in children with upper respiratory tract infection., Conclusions: PCV7 decreased the association between pneumococcal carriage and older age, 1 sibling in a family, history of acute otitis media and household exposure to smoking, but increased the association between pneumococcal carriage and breast-feeding.

Meticillin-resistant Staphylococcus aureus (MRSA) has been increasingly identified as the major cause of community-associated (CA) infections in previously healthy hosts since the late 1990s. CA-MRSA strains were recognised as a novel pathogen that is genetically different from healthcare-associated MRSA, and five major epidemic clones have been identified worldwide. In Taiwan, a significantly increasing rate of MRSA carriage and infection amongst healthy subjects was observed in the past decade. Up to 9.5% of healthy Taiwanese children carried MRSA in the nares and >50% of paediatric CA S. aureus infections were MRSA. The adult population was also affected, but this was relatively limited. The majority of CA-MRSA isolates in Taiwan belonged to the sequence type (ST) 59 lineage, defined by multilocus sequence typing, and were multiresistant to non-β-lactams. The clone of ST59 lineage can be further classified into at least two major clones by pulsed-field gel electrophoresis (PFGE) typing, staphylococcal chromosomal cassette mec (SCCmec) elements and Panton-Valentine leukocidin (PVL) genes. The clone characterised as ST59/PFGE type C/SCCmec IV/PVL-negative was prevalent amongst the colonising isolates, whereas ST59/PFGE type D/SCCmec V(T)/PVL-positive was prevalent amongst the clinical isolates. Evidence suggested that the ST59 CA-MRSA clone was not only circulating in Taiwan but also in other areas of the world. In this article, the current status of CA-MRSA in Taiwan was extensively reviewed. The information provided here is not only important for local public health but can also enhance a general understanding of the successful epidemic clones of CA-MRSA worldwide., (Copyright © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.)

Methicillin-resistant Staphylococcus aureus (MRSA) has been identified as a major cause of community-associated (CA) S. aureus infections in the past decade. The main reservoir in the community for MRSA and the factors contributing to its worldwide spread remain poorly defined. Between July 2005 and June 2008, a total of 6,057 healthy children 2 to 60 months of age were screened for carriage of S. aureus and Streptococcus pneumoniae in Taiwan. The prevalence and epidemiological factors influencing MRSA carriage were determined. MRSA strains were tested for antimicrobial susceptibility and underwent molecular characterization. The overall prevalences of MRSA and S. aureus carriage were 7.8% and 23.2%, respectively. A majority (88%) of MRSA isolates belonged to a common Asian-Pacific CA-MRSA lineage, multilocus sequence type 59, and were resistant to multiple non-beta-lactam antibiotics. The carriage rate of MRSA was higher among subjects 2 to 6 months old (P < 0.0001), residing in northern Taiwan (P = 0.0003), and enrolled later in the study (P < 0.0001). MRSA colonization was associated with the number of children in the family (adjusted odds ratio [aOR], 1.114; 95% confidence interval [CI], 1.002 to 1.240; P = 0.0463) and day care attendance (aOR, 1.530; 95% CI, 1.201 to 1.949; P = 0.0006). Breast feeding (P < 0.0001) and colonization with S. pneumoniae (P = 0.0170) were protective against MRSA colonization. We concluded that epidemic CA-MRSA strains increasingly colonized Taiwanese children between 2005 and 2008. The carriage rate varied significantly across different demographical features. Crowding was an independent environmental risk factor that might accelerate CA-MRSA transmission in the community.

From July 2005 to October 2006, a total of 3,046 children, of ages between 2 months and 5 years, presented for a well-child health care visit to one of three medical centers, which are located in the northern, central, and southern parts of Taiwan, and were surveyed for nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA). The overall prevalences of S. aureus and MRSA nasal carriage among the children were 23% and 7.3%, respectively (18% and 4.8% in the central region, 25% and 6.7% in the southern region, and 27% and 9.5% in the northern region). Of the 212 MRSA isolates (96%) available for analysis, a total of 10 pulsed-field gel electrophoresis (PFGE) patterns with two major patterns (C [61%] and D [28%]) were identified. One hundred forty-nine isolates (70%) contained type IV staphylococcal cassette chromosome mec (SCCmec) DNA, and 55 isolates (26%) contained SCCmec V(T). The presence of Panton-Valentine Leukocidin (PVL) genes was detected in 60 isolates (28%). Most MRSA isolates belonged to one of two major clones, characterized as sequence type 59 (ST59)/PFGE C/SCCmec IV/absence of PVL genes (59%) and ST59/PFGE D/SCCmec V(T)/presence of PVL genes (25%). We concluded that between 2005 and 2006, 7.3% of healthy Taiwanese children were colonized by MRSA in nares. MRSA harbored in healthy children indicates an accelerated spread in the community.

Nasal carriage of methicillin-resistant Staphylococcus aureus was detected in 18 (32%) of 57 children with community-acquired methicillin-resistant S. aureus infection and 30 (25%) of 121 household contacts. By genotyping comparison, 94% and 64% of the colonization isolates from the patients and the contacts, respectively, were indistinguishable from the clinical isolates.

A total of 427 subjects were surveyed for the carriage of Streptococcus pneumoniae before the introduction of pneumococcal conjugate vaccine in northern Taiwan. Positive results were identified in 27% of 94 children attending 6 classes in a child care center (CCC), 14% of 122 pupils attending 4 classes in 2 elementary schools, and 1.4% of 74 adolescents attending 3 classes in a junior middle school. None of 137 health care workers working in neonatal intensive care units of a university-affiliated hospital was colonized with S. pneumoniae. Three (12%) of 25 isolates from the children attending the CCC were susceptible to penicillin (MIC <0.1 microg/mL), whereas 8 (44%) of 18 isolates from the pupils and adolescents were susceptible (P = 0.0312). Of the 43 isolates, 11 serotypes were identified and serotypes/serogroups 6 (13 isolates), 23 (10 isolates), and 19 (7 isolates) were the 3 most common serotypes/serogroups. The genotypes of the 43 isolates were diverse, but it was not infrequently seen that several isolates from the subjects in a single class shared a common genotype. Conclusively, the carriage rate of S. pneumoniae is inversely correlated with the age of the subjects. The isolates from the children attending the CCC had a significantly higher penicillin-nonsusceptible rate than those from the pupils and adolescents. Transmission of the same clone in a single class may have frequently occurred.

In a nasal culture survey of school children, 5 (1.9%) of 262 school children and 18 (13%) of 137 health care workers (HCWs) were colonized with methicillin-resistant Staphylococcus aureus (MRSA). One common genotype accounted for most isolates from the school children and from the HCWs. Based on genotyping, MRSA strains circulating in the community in Taiwan were similar to the hospital strains.