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Molecular Epidemiologic Study of a Methicillin-resistant Staphylococcus aureus Outbreak at a Newborn Nursery and Neonatal Intensive Care Unit

  • Kang, Hyun Mi (Department of Pediatrics, College of Medicine, The Catholic University of Korea) ;
  • Park, Ki Cheol (Clinical Research Institute, Daejeon St. Mary's Hospital, College of Medicine, The Catholic University of Korea) ;
  • Lee, Kyung-Yil (Department of Pediatrics, College of Medicine, The Catholic University of Korea) ;
  • Park, Joonhong (Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea) ;
  • Park, Sun Hee (Division of Infectious Diseases, Department of Internal Medicine, College of Medicine, The Catholic University of Korea) ;
  • Lee, Dong-Gun (Division of Infectious Diseases, Department of Internal Medicine, College of Medicine, The Catholic University of Korea) ;
  • Kim, Jong-Hyun (Department of Pediatrics, College of Medicine, The Catholic University of Korea)
  • Received : 2019.07.03
  • Accepted : 2019.11.10
  • Published : 2019.12.25

Abstract

Purpose: This study aimed to investigate the molecular epidemiology of a methicillin-resistant Staphylococcus aureus (MRSA) outbreak at a newborn nursery and neonatal intensive care unit (NICU). Methods: During the outbreak, from August to September 2017, MRSA isolates collected from neonates and medical staff underwent genotyping and screened for virulence factors. Antibiotic susceptibilities were tested. Results: During the study period, 41 neonates were admitted at the nursery (n=27) and NICU (n=14). Of these, 7 had MRSA infections (skin infection [n=6] and sepsis [n=1]) and 4 were colonized with MRSA. Associated medical staff (n=32) were screened; three were nasal MRSA carriers. Staphylococcal chromosomal cassette mec (SCCmec) type II, sequence type (ST) 89, spa type t375 was found to be the skin infection outbreak causing strain, with multi-drug resistance including low-level mupirocin resistance. SCCmec type IVa, ST 72, and a novel spa type designated t17879, was the cause of MRSA sepsis. Many different types of MRSA were colonized on the neonates; however, SCCmec type IVa, ST 72, spa type t664 was colonized in both neonates and a NICU nurse. All MRSA isolates from colonized infants were positive for the Panton-Valentine leukocidin (PVL) toxin gene. Conclusions: The strain causing an outbreak of skin infections had multi-drug resistance. Also, MRSA colonized in the neonates were found to carry the PVL toxin gene. Because different strains are present during an outbreak, molecular epidemiologic studies are important to identify the outbreak strain and colonized strains which aid in effective control and prevention of future MRSA outbreaks.

목적: 본 연구에서는 신생아실과 신생아 중환자실에서 발생한 methicillin-resistant Staphylococcus aureus (MRSA) 유행에서 환자와 보균자에서 분리된 MRSA의 분자역학적 연관성을 조사하여 유행의 감염원과 전파경로를 파악하고자 하였다. 방법: MRSA 유행기간인 2017년 8월부터 9월까지 피부감염 및 패혈증 환자들과 보균자로부터 분리된 MRSA 균주를 대상으로 유전형 및 병원성 인자를 분석하고 항생제 감수성 결과를 수집하였다. 결과: 연구기간 동안 신생아실(n=27)과 신생아 중환자실(n=14)에 총 41명의 신생아들이 입원하였다. 그 중, 7명(피부감염[n=6], 패혈증[n=1])에서 MRSA 감염이 확진되었고, 보균자 4명이 발견되었다. 신생아와 접촉이 있는 의료진 32명 중 3명이 MRSA를 비강에 보균하였다. 피부감염 유행 원인 균주는 Staphylococcal chromosomal cassette mec (SCCmec) type II, sequence type (ST) 89, spa type t375였고, 뮤피로신 저농도 내성을 포함하여 항생제 다제내성을 보였다. 패혈증을 일으킨 균주는 SCCmec type IVa, ST 72, 새로운 spa type인 t17879였다. 신생아 4명에게 집락된 MRSA 균주들은 다양하였으나 SCCmec type IVa, ST 72, spa type t664가 의료진과 신생아 2명에서 공통적으로 분리되었다. Panton-Valentine leukocidin (PVL) toxin 유전자가 신생아에게 집락된 모든 균주에서 발견되었다. 결론: 피부감염 유행을 일으킨 MRSA 균주는 항생제 다제내성을 보이는 균주였다. 신생아 MRSA 보균자에게서 분리된 균주는 모두 PVL 독소 유전자를 보유하였다. 유행기간 동안 다양한 MRSA 균주가 신생아들에게서 분리되기 때문에, 효과적인 감염 관리 및 추가 환자발생의 차단을 위하여 분자역학조사를 통하여 원인균을 확인하고 전파경로를 파악하는 것이 중요하다.

Keywords

References

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