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)
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.
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.
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 me...
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.
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.
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문제 정의
The aim of this study was to investigate the molecular epidemiology of an MRSA outbreak at a nursery and NICU to identify the source of infection and understand the characteristics of the epidemic causing strain to prevent further transmission, prolonged carriage, and recolonization.
Identifying the outbreak strain as well as strains co-circulating in the intensive care unit and investigating their virulent characteristics through molecular epidemiologic studies broadens clinicians understanding about their clinical burden, and aids in controlling infections and transmission of strains that are possible threats to patients. This study showed the importance of eradicating not only the outbreak strain, but also decolonizing healthcare workers who could play a vital role in the transmission of MRSA with virulent potentials.
제안 방법
All patients with MRSA infections and MRSA colonizers underwent twice daily intranasal 2% mupirocin ointment (JW Pharmaceutical, Seoul, Korea) application for 7 days. Chlorhexidine bathing was not done due to controversies on its safety in use on neonates.
In this study, given that MLST did not provide a high enough discriminatory power to further distinguish between strains within the same MLST sequence types, spa typing was used. Spa typing was especially useful in determining the epidemiological relationship between the isolates from outborn neonate admitted for MRSA sepsis and the other MRSA colonized neonates, which were all SCCmec type IV, ST 72.
Healthcare workers are known to be possible sources or routes of MRSA transmission in hospital wards and intensive care units. In this study, through spa typing, it was possible to observe the significant role of healthcare workers on the spread of MRSA within the NICU, and how MRSA carriers who have constant contact with neonates can be a cause of prolonged MRSA transmission. During the outbreak, a nursery nurse was found to have MRSA nasal carriage early on after outbreak recognition.
,3) under the following PCR conditions: initial denaturation for 4 minutes at 94°C; 35 cycles of denaturation for 30 seconds at 94°C, annealing for 30 seconds at 53°C for the primers aroE, glpF, gmk, and pta, 57°C for the primers arcC, tpi, and ygiL, extension for 60 seconds at 72°C; and final extension for 4 minutes at 72°C. The sequences of each of the seven housekeeping genes were submitted to the MRSA database (https://pubmlst.org/saureus/) to designate a seven-integer number to identify the allelic profile for assigning the ST.
Therefore, the purpose of this study was to investigate an MRSA outbreak at a secondary referral university hospital's nursery and NICU to identify the source of infection and understand the characteristics of the epidemic causing strain to prevent further transmission, prolonged carriage, and recolonization.
To find the outbreak causing strain, MRSA isolates collected during the study period underwent genotyping. In this study, the skin infection causing outbreak strain was SCCmec type II, ST 89, t375.
Typing using MLST of the MRSA isolates was performed by amplification and sequencing of the internal fragments of the seven housekeeping genes (arcC, aroE, glpF, gmk, pta, tpi, and ygiL) using oligonucleotide primers as previously described by Enright et al.,3) under the following PCR conditions: initial denaturation for 4 minutes at 94°C; 35 cycles of denaturation for 30 seconds at 94°C, annealing for 30 seconds at 53°C for the primers aroE, glpF, gmk, and pta, 57°C for the primers arcC, tpi, and ygiL, extension for 60 seconds at 72°C; and final extension for 4 minutes at 72°C.
In 1-week intervals from the initial screening, a follow up culture was taken. When any of the sites were positive for MRSA, mupirocin oint application 3 times daily for 5 days was applied. The patients were also monitored for any symptoms or signs of MRSA infections, and upon discovery of any skin lesions or symptoms of sepsis, appropriate cultures from sites of infection were taken.
대상 데이터
This hospital has an average of about 150 normal and high-risk deliveries annually, and the nursery has 8 beds and NICU has 5 beds with one isolation room. A total of 11 nursing staff members are assigned to the nursery/NICU center. The nursery and NICU are separated into two isolated sections with glass walls and doors; and situated between the two sections is the nurses' station.
No new cases of MRSA infection or colonization occurred afterwards. A total of 41 patients in the nursery/NICU were screened, and 11 were positive for MRSA during the study period (Fig. 1).
An outbreak of MRSA occurred from August to September 2017, at a nursery and NICU center of a 670-bed secondary teaching and referral hospital in Korea (Fig. 1). This hospital has an average of about 150 normal and high-risk deliveries annually, and the nursery has 8 beds and NICU has 5 beds with one isolation room.
Therefore, the purpose of this study was to investigate an MRSA outbreak at a secondary referral university hospital's nursery and NICU to identify the source of infection and understand the characteristics of the epidemic causing strain to prevent further transmission, prolonged carriage, and recolonization. During the outbreak period, a total of 7 cases of MRSA infections occurred, 4 neonates were found to be colonizers, and 3 healthcare workers were found to be MRSA carriers.
During the outbreak which lasted for a span of 2 months, all patients admitted at the nursery/NICU were included as study participants. Upon admission during this period, all patients underwent initial nasal, axillary, and periumbilical MRSA skin swab cultures.
To find the source of MRSA, all 32 healthcare workers including nurses, staff physicians, residents, and interns working in the nursery/NICU and delivery room underwent MRSA initial screening by intranasal skin swab culture. Because X-ray technologists and NICU cleaning staff did not have direct contact with the patients, they were left out of the initial screening.
To use as a positive control, an MRSA isolate that had previously been identified and characterized as PFGE type USA 300, SCCmec type IVa, ST 8 was included in the study.
성능/효과
Of the total 9 MRSA isolates collected from neonates, SCCmec type IVa, ST 72 isolates (n=5) were resistant to penicillins, but susceptible to all other antibiotics. The outbreak causing SCCmec type II, ST 89, t375 strains (n=4) were multidrug resistant, showing resistance to antibiotics including penicillins, aminoglycosides, macrolides, clindamycin, and low-level resistance to mupirocin (minimum inhibitory concentration [MIC] 256 μg/mL) (Table 4).
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