Outbreak of Shewanella algae and Shewanella putrefaciens infections caused by a shared measuring cup in a general surgery unit in Korea.
OBJECTIVE
To control an outbreak of Shewanella algae and S. putrefaciens infections by identifying the risk factors for infection and transmission.


METHODS
Matched case-control study.


METHODS
A university-affiliated tertiary acute care hospital in Seoul, Republic of Korea, with approximately 1,600 beds.


METHODS
From June 20, 2003, to January 16, 2004, a total of 31 case patients with Shewanella colonization or infection and 62 control patients were enrolled in the study.


METHODS
Requirement to use single-use measuring cups and standard precautions (including hand washing before and after patient care and use of gloves).


RESULTS
S. algae or S. putrefaciens was isolated from blood, for 9 (29.0%) of 31 patients who acquired one of the organisms; from bile, for 8 (25.8%), and from ascitic fluid, for 8 (25.8%). The attack rate of this outbreak was 5.8% (31 patients infected or colonized, of 534 potentially exposed on ward A) and the pathogenicity of the two species together was 77.4% (24 patients infected, of 31 who acquired the pathogens). The estimated incubation period for Shewanella acquisition was 3-49 days. Using logistic analysis, we identified the following risk factors: presence of external drainage catheters in the hepatobiliary system (odds ratio [OR], 20; P < .001), presence of hepatobiliary disease (OR, 6.4; P < .001), admission to the emergency department of the hospital (OR, 2.9; P = .039), wound classification of "contaminated" or "dirty or infected" (OR, 16.5; P = .012), an American Society of Anesthesiologists score of 3 or higher (OR, 8.0; P = .006), duration of stay in ward A (OR, 1.1; P < .001), and, for women, an age of 60-69 years (OR, 13.3; P = .028). A Shewanella isolate was recovered from the surface of a shared measuring cup, and 12 isolates of S. algae showed the same pulsed-field gel electrophoresis pattern.


CONCLUSIONS
This Shewanella outbreak had a single-source origin and spread by contact transmission via a contaminated measuring cup. Shewanella species are emerging as potentially serious human pathogens in hospitals and could be included in hospital infection surveillance systems.
Oh
Hyang Soon
HS
Department of Infection Control Service, Seoul National University Hospital, Seoul, Republic of Korea .
Kum
Kyung Ah
KA
Kim
Eui-Chong
EC
Lee
Hoan-Jong
HJ
Choe
Kang Won
KW
Oh
Myoung Don
MD
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D004196:Disease Outbreaks; D004866:Equipment Contamination; D004865:Equipment and Supplies, Hospital; D005260:Female; D013502:General Surgery; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology / Q000209:etiology / Q000382:microbiology / Q000635:transmission; D006746:Hospital Bed Capacity, 500 and over; D006757:Hospital Units; D006801:Humans; D007723:Korea; D008297:Male; D008875:Middle Aged; D020592:Shewanella / Q000145:classification / Q000302:isolation & purification*; D020614:Shewanella putrefaciens / Q000302:isolation & purification*