• Clinical and Experimental Pediatrics
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• v.46 no.1
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• pp.24-32
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• 2003

Purpose : Nosocomial infection with Staphylococcus aureus, especially methicillin resistant S. aureus, has become a serious concern in the neonatal intensive care unit. The aim of this study is to investigate the virulence factors, and the relationship between the antibiotic resistance and the associated genes of Staphylococcus aureus isolated from nasal cavity of neonates. Methods : Fifty one isolates of S. aureus were obtained from nasal swab taken in 28 neonates in the NICU and nursery of Pusan National University Hospital between February and May, 2001. They were tested in regard to antibiotic susceptibility, coagulase test and typing, plasmid DNA profile, as well as reactivity to enterotoxin A-E(sea, seb, sec, sed, see) genes and toxic shock syndrome toxin-1(tst) gene by polymerase chain reaction(PCR). Associated genes such as mecA, mecR1, mecI, and femA were also determined by PCR. The origin of MRSA strains was assessed using DNA fingerprinting by arbitrarily-primed polymerase chain reaction(AP-PCR). Results : Twenty three(45.1%) and six(11.8%) isolates were resistant to oxacillin and vancomycin respectively. Multidrug resistance to three or more of the antibiotics tested was observed in 51.0% of the isolates. Forty two isolates were coagulase positive and twenty two isolates had mecA gene. Sixteen isolates had both mecA and femA genes and had type I-III plasmids. 64.7% of isolates carried sec gene, and 80.4% carried tst gene. DNA fingerprinting by AP-PCR for 12 MRSA strains showed 10 distinct patterns, suggesting different origins. Conclusion : We confirmed that the prevalence of nasal carriage of S. aureus and the incidence of antimicrobial-resistant S. aureus, especially vancomycin resistance, is very high in neonates who were admitted in NICU and nursery. It is possible that these pathogens are responsible for serious nosocomial infections in neonates. The need for improved surveillance and continuous control of pathogens is emphasized.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.286-297
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• 2016

Clostridium perfringens is both a ubiquitous environmental bacterium and a major cause of human gastrointestinal disease, and C. perfringens food poisoning ranks among the most common gastrointestinal diseases in developed countries. 120 isolates of C. perfringens were obtained from food-poisoning outbreaks in 2013~2014, Gyeonggi-do. Using PCR, all 120 isolates were identified as C. perfringens type A. Of the tested isolates, 49 isolates carried the cpe gene, 71 isolates carried the cpb2 gene. The outbreak cases of cpb2 and cpe /cpb2 genes were 7 and 7, whereas the outbreak cases of cpe-gene were 2. The epidemiological relationship between C. perfringens isolates has previously been investigated chiefly by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The genetics relatedness of the isolates raged from 53.5-100% and 75 district PFGE type were observed. The PFGE results revealed a wide genetic diversity among the 64 cpb2 carrying isolates (except 7 isolates), while 46 cpe-carrying isolates (except 3 isolates) showed a high genetic similarity. The MLST analysis revealed that 14 cpe isolates (cpe-chromosomal isolates) belong to a distinct cluster that is significantly distant from all the other cpb2 isolates (cpe-plasmid carrying and cpe-negative isolates). The isolates carrying a cpb2 appear to be rarely related, and are more variable than chromosomal cpe isolates. The results suggest that the cpe-positive outbreak isolates showed close genetic relation, whereas the cpb2-positive isolates revealed a wide genetic diversity.

• Pediatric Infection and Vaccine
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• v.9 no.1
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• pp.79-84
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• 2002

Purpose : About 41% of obtained group A streptococci in the 1998 was reported as erythromycin-resistant streptococci in Seoul, Korea. The most common T serotype was T12, followed by T4 and T28. We'd like to monitor the serological changes and antibiotic sensitivity test of Streptococcus pyogenes obtained from the patients with pharyngotonsillitis and invasive diseases from 1999 through 2001. Also, it could be proposed to choose the proper antibiotic selection in the area where the rate of erythromycin-resistant streptococci is high. Methods : From Jan. 1999 to Oct. 2001, 208 isolates of group A streptococci were collected from inpatients and outpatients with pharyngotonsillitis, scarlet fever, and invasive infections in Seoul and Southern part of peninsula. All isolates were serotyped by T-agglutination, minimum inhibitory concentrations(MICs) which were determined by agar dilution methods, according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS). Results : The most common T serotype was T12(29.8%), followed by T1(23.1%), T4 (14.9%). T1 was prominent serotype compared with previous year. T serotyping, among 25 isolates obtained from the patients with scarlet fever in Southern part of peninsula mostly, was T12, T1, and T4 in order of frequency. All the isolates tested were susceptible to penicillin, cefprozil, vancomycin, ceftriaxone, and chloramphenicol. However, 23 isolates(14.2%) was resistant to erythromycin and 18 isolates(11.1%) was resistant to clarithromycin. Serotype T12 was found to be the most resistant serotype to erythromycin and/or clarithromycin. Conclusion : High rate of erythromycin-resistant streptococci which surveyed in 1998 were reduced to 14.2% in this study. We should have to further evaluate the reason of decreased resistant strains and consider the resistant strains of streptococci in choosing the antibiotics. There was no serological characteristics according to the types of disease entities. Between the serologic distributions in Seoul and the Southern part of peninsula area are same, we could presume that the serological typing of strains obtained over the country may be not different.