Nosocomial Outbreak of a Novel Extended-Spectrum β-Lactamase Salmonella enterica Serotype Isangi Among Surgical Patients.
OBJECTIVE Nosocomial outbreaks caused by Salmonella are rare. We describe the investigation and control of a cluster of novel extended-spectrum β-lactamase (ESBL) Salmonella enterica serotype Isangi in a hospital in southeastern Michigan. METHODS An epidemiologic investigation, including case-control study, assessment of infection control practices and environmental cultures, was performed to identify modes of transmission. Healthcare workers (HCWs) exposed to case patients were screened. Strain relatedness was determined using pulsed-field gel electrophoresis (PFGE); ESBL confirmation was conducted using real-time PCR. Control measures were implemented to prevent further transmission. RESULTS Between September 2 and October 22, 2015, 19 surgical patients, including 10 organ transplant recipients and 1 HCW, had positive S. Isangi cultures. Of these case patients and HCW, 13 had gastroenteritis, 2 had bacteremia, 1 had surgical-site infection, and 4 were asymptomatic. Pulsed-field gel electrophoresis (PFGE) showed 89.5% similarity among the isolates in these cases. Isolates with resistant-phenotypes possessed plasmid-mediated CTX-M15 ESBL. A total of 19 case patients were compared with 57 control participants. Case patients had significantly higher odds of exposure to an intraoperative transesophageal (TEE) probe (adjusted odds ratio 9.0; 95% confidence interval, 1.12-72.60; P=.02). Possible cross-transmission occurred in the HCW and 2 patients. Cultures of TEE probes and the environment were negative. The outbreak ended after removal of TEE probes, modification of reprocessing procedures, implementation of strict infection control practices, and enhanced environmental cleaning. CONCLUSIONS We report the first nosocomial ESBL S. Isangi outbreak in the United States. Multiple control measures were necessary to interrupt transmission of this gastrointestinal pathogen. Exposure to possibly contaminated TEE probes was associated with transmission. Periodic monitoring of reprocessing procedures of TEE probes may be required to ensure optimal disinfection. Infect Control Hosp Epidemiol 2016;37:954-961.
Department of Infectious Disease, Henry Ford Hospital, Detroit, Michigan.
Geehan
G
Suleyman
Department of Pathology, Henry Ford Hospital, Detroit, Michigan.
Robert
R
Tibbetts
Research Laboratory, Henry Ford Hospital, Detroit, Michigan.
Mary Beth
MB
Perri
Research Laboratory, Henry Ford Hospital, Detroit, Michigan.
Dora
D
Vager
Public Health Sciences, Henry Ford Hospital, Detroit, Michigan.
Yuan
Y
Xin
Department of Infectious Disease, Henry Ford Hospital, Detroit, Michigan.
Katherine
K
Reyes
Department of Pathology, Henry Ford Hospital, Detroit, Michigan.
Linoj
L
Samuel
Infection Control, Henry Ford Hospital, Detroit, Michigan.
Eman
E
Chami
Infection Control, Henry Ford Hospital, Detroit, Michigan.
Patricia
P
Starr
Infection Control, Henry Ford Hospital, Detroit, Michigan.
Jennifer
J
Pietsch
Department of Infectious Disease, Henry Ford Hospital, Detroit, Michigan.
Marcus J
MJ
Zervos
Department of Infectious Disease, Henry Ford Hospital, Detroit, Michigan.
George
G
Alangaden
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003428:Cross Infection / Q000453:epidemiology* / Q000517:prevention & control; D004196:Disease Outbreaks; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D008297:Male; D008824:Michigan / Q000453:epidemiology; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology*; D012480:Salmonella Infections / Q000453:epidemiology* / Q000517:prevention & control; D065288:Serogroup; D055815:Young Adult; D001618:beta-Lactamases / Q000302:isolation & purification*
D001618:beta-Lactamases