An outbreak of Serratia marcescens on the neonatal unit: a tale of two clones.
Serratia spp. are an important cause of hospital-acquired infections and outbreaks in high-risk settings. Twenty-one patients were infected or colonized over a nine-month period during 2001-2002 on a neonatal unit. Twenty-two isolates collected were examined for antibiotic susceptibility, beta-lactamase production and genotype. Random-amplified polymorphic DNA polymerase chain reaction and pulsed-field gel electrophoresis revealed that two clones were present. The first clone caused invasive clinical infection in four babies, and was subsequently replaced by a non-invasive clone that affected 14 babies. Phenotypically, the two strains also differed in their prodigiosin production; the first strain was non-pigmented whereas the second strain displayed pink-red pigmentation. Clinical features suggested a difference in their pathogenicity. No environmental source was found. The outbreak terminated following enhanced compliance with infection control measures and a change of antibiotic policy. Although S. marcescens continued to be isolated occasionally for another five months of follow-up, these were sporadic isolates with distinct molecular typing patterns.
David
M D
MD
Microbiology Department, City Hospital, Sandwell and West Birmingham Hospitals NHS Trust, UK. miruna.david@heartofengland.nhs.uk
Weller
T M A
TM
Lambert
P
P
Fraise
A P
AP
D002999:Clone Cells; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D017053:Infection Control / Q000379:methods*; D007363:Intensive Care Units, Neonatal; D019105:Random Amplified Polymorphic DNA Technique; D016868:Serratia Infections / Q000453:epidemiology*; D012706:Serratia marcescens / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D006113:United Kingdom / Q000453:epidemiology; D001618:beta-Lactamases / Q000096:biosynthesis
D001618:beta-Lactamases