Coincidental outbreak of methicillin-resistant Staphylococcus aureus in a hematopoietic stem cell transplantation unit.
BACKGROUND
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common nosocomial pathogens among hospital-acquired infections, and immunocompromised patients are highly susceptive to infection. The molecular typing of isolated strains is a common method for tracing an outbreak of MRSA, but experience with this approach is still limited in the hematopoietic stem cell transplantation (HSCT) ward.


METHODS
We experienced 6 cases of MRSA infection/colonization in our 26-bed HSCT ward during a 4-week period. This unusual outbreak strongly suggested that the same MRSA strain was involved despite strict isolation and aseptic patient care. Clarification of the transmission pattern was critical, and we applied pulsed-field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) assays for evaluation.


CONCLUSIONS
In four of the six cases, the pattern of bands examined by PFGE and AFLP analyses supported the idea that direct person-to-person transmission was very unlikely and the outbreak was coincidental. This experience highlights the clinical value of molecular typing methods for the clinical epidemiological assessment of MRSA outbreak.
Imataki
Osamu
O
Hematopoietic Stem Cell Transplantation Unit, National Cancer Center Hospital, Tokyo, Japan.
Makimoto
Atsushi
A
Kato
Shingo
S
Bannai
Takahiro
T
Numa
Naomi
N
Nukui
Yoko
Y
Morisawa
Yuji
Y
Ishida
Toshihiko
T
Kami
Masahiro
M
Fukuda
Takahiro
T
Mori
Shin-ichiro
S
Tanosaki
Ryuji
R
Takaue
Yoichi
Y
D000328:Adult; D002173:Cancer Care Facilities / Q000592:standards; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation / Q000592:standards; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D012150:Polymorphism, Restriction Fragment Length; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*