Antimicrobial susceptibility patterns and ␤-lactam resistance mechanisms of 544 Haemophilus influenzae isolates through the nationwide Acute Respiratory Infections Surveillance (ARIS) network in Korea during 2005 and 2006 were determined. Resistance to ampicillin was 58.5%, followed by resistance to cefuroxime (23.3%), clarithromycin (18.7%), cefaclor (17.0%), amoxicillin-clavulanate (10.4%), and chloramphenicol (8.1%). Levofloxacin and cefotaxime were the most active agents tested in this study. ␤-Lactamase production (52.4%) was the main mechanism of ampicillin resistance, affecting 96.1% of TEM-1-type ␤-lactamase. According to their ␤-lactam resistance mechanisms, all isolates were classified into the following groups: ␤-lactamase-negative, ampicillin-sensitive (BLNAS) strains (n ‫؍‬ 224; 41.5%); ␤-lactamase-positive, ampicillin-resistant (BLPAR) strains (n ‫؍‬ 255; 47.2%); ␤-lactamase-negative, ampicillin-resistant (BLNAR) strains (n ‫؍‬ 33; 6.1%); and ␤-lactamase-positive, amoxicillin-clavulanate-resistant (BLPACR) strains (n ‫؍‬ 28; 5.2%). Among the BLNAR and BLPACR strains, there were various patterns of multiple-amino-acid substitutions in penicillin-binding protein 3. Particularly, among BLNAR, group III isolates, which had three simultaneous substitutions (Met377Ile, Ser385Thr, and Leu389Phe), were identified for the first time in Korea. Three group III strains displayed the highest MIC of cefotaxime (1 to 2 g/ml). The results indicate the importance of monitoring a changing situation pertaining to the increase and spread of BLNAR and BLPACR strains of H. influenzae for appropriate antibiotic therapy for patients with respiratory tract infections in Korea.

A longitudinal analysis was carried out of the colonization by four potential respiratory pathogens -Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus -in 165 healthy children (aged 3-7 years) attending three kindergartens and 417 healthy children (aged 7-10 years) attending an elementary school in Seoul, Korea, by four consecutive examinations over 1 year. The prevalence of nasal carriers of one or more of four bacteria was found to be higher in younger children (¡7 years) (mean 68.6 %) than that in older children (mean 46.8 %). The mean rates of nasal carriage of Strep. pneumoniae, H. influenzae, M. catarrhalis and Staph. aureus were 16.8, 18.9, 20.2 and 18.2 %, respectively. Colonization by Strep. pneumoniae, H. influenzae and M. catarrhalis was higher in pre-school children (28.6, 32.4 and 35.0 %, respectively) than in school children (12.2, 13.6 and 14.3 %, respectively). Carriage trends differed with age, with Strep. pneumoniae, H. influenzae and M. catarrhalis colonization decreasing with age but Staph. aureus colonization increasing. Positive associations of co-occurrence between Strep. pneumoniae, H. influenzae and M. catarrhalis were evident, with a significant negative association evident between Staph. aureus and the other three bacteria. A better understanding of the colonization and interaction of potential respiratory pathogens may be important for predicting changes in bacterial ecology and for designing control strategies that target bacterial colonization in upper respiratory tract infections.

We investigated changes in serotypes and antimicrobial susceptibilities among 386 isolates of invasive Streptococcus pneumoniae collected from numerous hospitals in Korea from 1996 to 2008. Serotypes 19F (9.8 %), 23F (8.3 %), 19A (7.8 %), 6A (7.5 %), 3 (7.3 %), 9V (6.5 %), 6B (6.2 %), 14 (4.9 %), 1 (3.9 %), 11A (3.9 %) and 4 (3.1 %) represented 69.2 % of all isolates. While the overall proportion of PCV7 serotypes was stable over time, we observed modest decreases in children ,5 years old and in adults ¢65 years old between 1996-1999 and 2007-2008. An increased prevalence of non-PCV7 serotypes in these age groups was primarily attributable to an increase in serotypes 3, 6A and 19A. Most invasive S. pneumoniae isolates showed high resistance rates to erythromycin (74.9 %), tetracycline (71.1 %) and clindamycin (61.7 %). Between 1996Between -2003Between and 2004Between -2008, non-susceptibility rates to cefotaxime and multi-drugs (three or more classes) in PCV7 serotypes showed a declining trend, while in non-PCV7 serotypes there was an increasing trend. Non-PCV7 serotypes 6A and 19A, which mostly exhibited multidrug-resistant phenotypes (69.0 % and 76.7 % respectively), increased between

Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and can cause nosocomial infections in immunocompromised patients. Recently the presence of NTM in public drinking water and hospital water distribution systems has been reported. Their ability to form biofilms and their resistance to chlorine both contribute to their survival and colonization in water distribution systems. Here we analyzed thirty-two hospital tap water samples that were collected from different locations in three hospitals so as to evaluate the prevalence of NTM species. The water samples were concentrated by membrane filtration and then eluted with sterilized water following sonication. Two-step direct PCR targeting the rpoB gene, restriction fragment length polymorphism (RFLP) using the MspI restriction enzyme, and sequence analysis were performed for identification of NTM to the species level. The sequences of each PCR product were analyzed using BLASTN. Seven samples (7/32, 21.9%) were positive for NTM as determined by nested-PCR. The PCR-RFLP results indicated five different patterns among the seven positive PCR samples. The water-born NTM were identified, including M. peregrinum, M. chelonae (2 cases), M. abscessus, M. gordonae (2 cases), and Mycobacterium sp. JLS. The direct two-step PCR-RFLP method targeting the rpoB gene was effective for the detection and the differentiation of NTM species from hospital tap water.