Transmission of Methicillin-Resistant Staphylococcus aureus to a Microbiologist
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《新英格兰医药杂志》
To the Editor: Strains of methicillin-resistant Staphylococcus aureus that produce Panton–Valentine leukocidin and that are associated with soft-tissue infections and necrotizing pneumonia are emerging worldwide,1 most often as a source of community-acquired infections but also as a source of nosocomial infections.2,3,4 We report a case of infection with such a strain that occurred in a laboratory and that affected an experienced microbiologist in the absence of a prior skin lesion.
Acute paronychia on the left middle finger developed in a 37-year-old microbiologist seven days after he had worked with a strain of methicillin-resistant S. aureus that produced Panton–Valentine leukocidin. After surgical drainage, he was treated with local antiseptics (a daily finger bath of 5 percent povidone–iodine for two weeks). Because pus continued to be identified in the wound, a chlorhexidine finger bath twice a day and the use of wet chlorhexidine bandages were then recommended for one week. The infection did not improve, and a second surgical drainage was performed. Culture of the wound showed the presence of methicillin-resistant S. aureus. The isolate was resistant to oxacillin and kanamycin; was of intermediate susceptibility to fusidic acid; and was susceptible to tobramycin, rifampin, and the fluoroquinolones — as were the isolates of leukocidin-producing, methicillin-resistant S. aureus that were being studied at that time in the laboratory. Nasal swabs from the patient were positive for leukocidin-producing, methicillin-resistant S. aureus, whereas nasal swabs from all the other laboratory workers involved in the work on this strain and from family members of the infected microbiologist were negative.
The microbiologist was then treated with ciprofloxacin (1000 mg per day) and rifampin (25 mg per kilogram of body weight per day) for one month. Nasal decontamination with the use of mupirocin (Bactroban 2 percent) three times a day for one week and full-body–shower washing with 4 percent chlorhexidine gluconate (Hibiscrub) twice a day for two days were prescribed. Subsequent nasal swabs from the patient were negative for methicillin-resistant S. aureus.
Pulsed-field gel electrophoresis (Figure 1) revealed that the strain with which the microbiologist had been infected was genetically indistinguishable from one of the isolates with which he had been working before his infection. A series of genetic traits widespread in strains of methicillin-resistant S. aureus that produce Panton–Valentine leukocidin (the PVL gene, the lukE-lukD genes, the agr3 allele, and SCCmec type IV)1,5 were also identified in the isolated strain of methicillin-resistant S. aureus.
Figure 1. Pulsed-Field Gel Electrophoresis of Five Strains of Methicillin-Resistant Staphylococcus aureus That Produce Panton–Valentine Leukocidin.
Lane P shows the strain that infected the patient, a microbiologist. Lanes S1 through S4 show the strains with which the microbiologist was working before he was infected.
This report highlights the need for caution in handling methicillin-resistant S. aureus that produces Panton–Valentine leukocidin. Reports of community outbreaks of infections with these strains underscore the need for careful handling of all microbiologic specimens in order to avoid the risk of transmission and nosocomial outbreaks.
Patrice Nordmann, M.D., Ph.D.
Thierry Naas, Ph.D.
H?pital de Bicêtre
F-94275 Le Kremlin-Bicêtre, France
Acute paronychia on the left middle finger developed in a 37-year-old microbiologist seven days after he had worked with a strain of methicillin-resistant S. aureus that produced Panton–Valentine leukocidin. After surgical drainage, he was treated with local antiseptics (a daily finger bath of 5 percent povidone–iodine for two weeks). Because pus continued to be identified in the wound, a chlorhexidine finger bath twice a day and the use of wet chlorhexidine bandages were then recommended for one week. The infection did not improve, and a second surgical drainage was performed. Culture of the wound showed the presence of methicillin-resistant S. aureus. The isolate was resistant to oxacillin and kanamycin; was of intermediate susceptibility to fusidic acid; and was susceptible to tobramycin, rifampin, and the fluoroquinolones — as were the isolates of leukocidin-producing, methicillin-resistant S. aureus that were being studied at that time in the laboratory. Nasal swabs from the patient were positive for leukocidin-producing, methicillin-resistant S. aureus, whereas nasal swabs from all the other laboratory workers involved in the work on this strain and from family members of the infected microbiologist were negative.
The microbiologist was then treated with ciprofloxacin (1000 mg per day) and rifampin (25 mg per kilogram of body weight per day) for one month. Nasal decontamination with the use of mupirocin (Bactroban 2 percent) three times a day for one week and full-body–shower washing with 4 percent chlorhexidine gluconate (Hibiscrub) twice a day for two days were prescribed. Subsequent nasal swabs from the patient were negative for methicillin-resistant S. aureus.
Pulsed-field gel electrophoresis (Figure 1) revealed that the strain with which the microbiologist had been infected was genetically indistinguishable from one of the isolates with which he had been working before his infection. A series of genetic traits widespread in strains of methicillin-resistant S. aureus that produce Panton–Valentine leukocidin (the PVL gene, the lukE-lukD genes, the agr3 allele, and SCCmec type IV)1,5 were also identified in the isolated strain of methicillin-resistant S. aureus.
Figure 1. Pulsed-Field Gel Electrophoresis of Five Strains of Methicillin-Resistant Staphylococcus aureus That Produce Panton–Valentine Leukocidin.
Lane P shows the strain that infected the patient, a microbiologist. Lanes S1 through S4 show the strains with which the microbiologist was working before he was infected.
This report highlights the need for caution in handling methicillin-resistant S. aureus that produces Panton–Valentine leukocidin. Reports of community outbreaks of infections with these strains underscore the need for careful handling of all microbiologic specimens in order to avoid the risk of transmission and nosocomial outbreaks.
Patrice Nordmann, M.D., Ph.D.
Thierry Naas, Ph.D.
H?pital de Bicêtre
F-94275 Le Kremlin-Bicêtre, France