Two Nosocomial Outbreaks of Sepsis Caused by Serratia marcescens, which Occurred in July 1999 and January 2002-Tokyo

Abstract

Two nosocomial outbreaks of sepsis caused by Serratia marcescens, which occurred in Tokyo were the following cases. CASE A: In July 1999, 10 inpatients admitted to the third floor ward of the General Hospital A, developed sudden onset of high fever, coagulation disorders (disseminated intravascular coagulation), and acute renal failure, of which 5 died. Twenty-one strains of Serratia marcescens were isolated from the inpatient's blood and urine, nurse fingers and environmental samples from floor and cooling tower. Serratia infection was strongly suspected as the cause of sepsis. These cases were defined as "inpatients who developed fever 38 degrees C or more during July 26 to 29 and from whom S. marcescens was isolated by blood culture". Ten isolates were detected from the blood. In order to investigate the background of S. marcescens isolation in the hospital and to compare molecular and biochemical characteristics of S. marcescens, cultures were attempted from samples of other inpatients and staffs and hospital environment. Those were classified into 9 groups by various different typings: biotyping with Api Rapid 20; susceptibility typing of antimicrobial agents tested; pulsed-field gel electrophoresis (PFGE) typing of SpeI- or Xba I-restricted chromosome. All 10 isolates causing sepsis were found to be in the same group. CASE B: In January 2002, 24 inpatients, admitted to Neurosurgical Hospital B, developed sudden onset of high fever, of which 7 died. S. marcescens was isolated from a towel, environmental samples and inpatients. These cases were defined as "inpatients who developed fever of 38.5 degrees C and S. marcescens isolated by blood culture". Twelve strains were isolated from the blood samples in 12 cases. In order to investigate the background of S. marcescens isolation in the hospital, cultures were attempted from other inpatient's urine and environmental samples from medical tape, Tshake and a towel. These isolates were classified into 3 groups by the previous typings; biotyping with Api Rapid 20; susceptibility typing of antimicrobial agents tested; and PFGE typing. All 12 isolates in 12 cases were found to be in the same group. These cases of 2 nosocomial outbreaks of sepsis were defined as "in-patient who developed high fever and S. marcescens isolated by blood culture". However in both cases transmission routes of Serratia infection remain unknown by field investigation.

Experimental confirmation of Serratia marcecsens contamination in multiple-dose vials of heparin-saline solution

“…2,4,9 Contamination of the HS of MDV by organisms such as S. marcescens can lead to life-threatening infections, although the risk of MDV contamination is low. 5,6,10,11 To prevent contamination, a disposable syringe for HS for heparin locks is available commercially, but it is much more expensive than the MDVs used for heparin stock solutions for heparin locks. If HS in MDVs is chosen, guidelines of the U.S. Centers for Disease Control and Prevention should be followed, considering the serious consequences of a BSI resulting from such contamination.…”

“…1 Subsequently, the contamination is spread to another vial via the syringe or directly to the HS prepared for heparin locks by repeated use of the contaminated HS. 1,5,6,12,11 Viable cells of isolate I2 carried over into the HS of the MDV when the septum was pierced with a syringe needle were detected at an MIS of 10 3 s cfu/ml for wet cell suspensions in HS or MHB, which is four orders of magnitude smaller than the MIS required under dry conditions (Table 1). Moreover, the viable cell number carried over into the internal lumen of the needle was much greater than that on the outside surface of the needle.…”

“…11 Detection of viable cells carried over into the HS by puncturing the MDV Isolate I2 was cultured in 5 ml of Müller-Hinton broth (MHB) at 36°C for 18 h. The culture was then centrifuged at 3000 g for 10 min and washed twice with an equal volume of HS without 1% BA, which was previously prepared by adding 1000 units of heparin (Wako Pure Chemicals, Tokyo, Japan) per milliliter of saline followed by filtration through a Millex-GV filter (Millipore, MA, USA). The cell suspension was next adjusted to an optical density at 600 nm (OD600) of 0.2 to 0.3 (approx.…”

“…12 In Japan, contamination of HS in MDVs by Serratia marcescens recently caused lifethreatening infection. 11 Such contamination has been experimentally investigated, but rarely for various isolates of S. marcescens. 1,3,6,8,12,13 Various MDVs of HS with or without a preservative such as 1% benzyl alcohol (BA) are commercially available.…”

“…[1][2][3][4][5][6][7][8][9] Nevertheless, serious hospital-acquired infection (HAI), presumably from bacterial contamination of MDVs, has been only sporadically reported. 6,8,10,11 The contamination of stock heparin-saline solution (HS) in MDVs is a risk factor for an outbreak of HAI-related bloodstream infection (BSI) caused by contamination after or during preparation of HS for heparin locks. 12 In Japan, contamination of HS in MDVs by Serratia marcescens recently caused lifethreatening infection.…”