Hanley J Ho1, Cheng Yen Toh2, Brenda Ang3, Prabha Krishnan4, Raymond T P Lin5, My-Van La6, Angela Chow7. 1. Department of Clinical Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore. Electronic address: hanleyho@gmail.com. 2. Infection Control Unit, Tan Tock Seng Hospital, Singapore, Singapore. 3. Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore, Singapore. 4. Department of Laboratory Medicine, Tan Tock Seng Hospital, Singapore, Singapore. 5. National Public Health Laboratory, Ministry of Health, Singapore, Singapore; Department of Laboratory Medicine, National University Health System, Singapore, Singapore. 6. National Public Health Laboratory, Ministry of Health, Singapore, Singapore. 7. Department of Clinical Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore; Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.
Abstract
BACKGROUND: Autochthonous infections with New Delhi metallo-β-lactamase-1 (NDM-1)-producing Enterobacteriaceae have been reported in Singapore since 2011, but occurrences of nosocomial transmission have not. We report an outbreak of NDM-1-producing Enterobacter cloacae among adults admitted to an acute hospital's general ward. METHODS: On detecting the index case with a culture specimen positive for NDM-1-producing E cloacae, active case finding was conducted by screening all possible patient contacts. On-site ward assessment was performed, and electronic patient medical records were reviewed to conduct a case-control study to identify factors associated with colonization. RESULTS: Of 55 screened patient contacts, 3 further cases were detected, with isolates genetically related to the index case. None of these 4 cases was housed within the same cubicle. However, 3 were managed by the same medical team. Being managed by this team was positively associated with being a case (adjusted odds ratio = 15.64; 95% confidence interval, 0.91-270.27; P = .06) after adjusting for age, sex, Charlson comorbidity index score, and recent antibiotic use. CONCLUSION: Our report suggests nosocomial transmission of NDM-1-producing E cloacae occurred via health care staff. Improvements in infection control measures, especially pertaining to staff hand hygiene practices and ward staffing, are needed to reduce the spread of highly resistant pathogens, such as NDM-1-producing Enterobacteriaceae.
BACKGROUND: Autochthonous infections with New Delhi metallo-β-lactamase-1 (NDM-1)-producing Enterobacteriaceae have been reported in Singapore since 2011, but occurrences of nosocomial transmission have not. We report an outbreak of NDM-1-producing Enterobacter cloacae among adults admitted to an acute hospital's general ward. METHODS: On detecting the index case with a culture specimen positive for NDM-1-producing E cloacae, active case finding was conducted by screening all possible patient contacts. On-site ward assessment was performed, and electronic patient medical records were reviewed to conduct a case-control study to identify factors associated with colonization. RESULTS: Of 55 screened patient contacts, 3 further cases were detected, with isolates genetically related to the index case. None of these 4 cases was housed within the same cubicle. However, 3 were managed by the same medical team. Being managed by this team was positively associated with being a case (adjusted odds ratio = 15.64; 95% confidence interval, 0.91-270.27; P = .06) after adjusting for age, sex, Charlson comorbidity index score, and recent antibiotic use. CONCLUSION: Our report suggests nosocomial transmission of NDM-1-producing E cloacae occurred via health care staff. Improvements in infection control measures, especially pertaining to staff hand hygiene practices and ward staffing, are needed to reduce the spread of highly resistant pathogens, such as NDM-1-producing Enterobacteriaceae.