Factors associated with emergence of pristinamycin-resistant Staphylococcus aureus in a dermatology department: a case-control study.
BACKGROUND
Pristinamycin is used for the treatment of Staphylococcus aureus skin infection. Staphylococcus aureus pristinamycin resistance is usually low. The frequency of pristinamycin-resistant S. aureus (PRSA) increased in the Caen University Hospital dermatology department from 1% in 1998 to >11% in 1999-2002.


OBJECTIVE
This study aimed to identify the factors associated with PRSA acquisition.


METHODS
Incidences of PRSA and pristinamycin consumption were calculated for the dermatology department and for the rest of the hospital from 1997 to 2007. Individual factors of PRSA acquisition in the dermatology department from 2000 to 2001 were analysed in a retrospective case-control study including 23 cases of PRSA skin colonization or infection and 46 controls with pristinamycin-susceptible S. aureus. Clonal relatedness of isolates was analysed by pulsed-field gel electrophoresis and pristinamycin resistance genes were detected by polymerase chain reaction. Conditional logistic regression was performed to analyse the relationship between pristinamycin resistance and epidemiological and microbiological data.


RESULTS
PRSA frequency and pristinamycin consumption were significantly higher in the dermatology department than in other hospital departments. Two epidemic clones of two and six isolates were found for periods of 1 and 2 months, respectively. Thirteen of the 23 PRSA isolates (57%), including all isolates of the two epidemic clones, were found 48 h after the hospitalization or later. PRSA was associated with pristinamycin use during the previous year [odds ratio (OR) 5.60, 95% confidence interval (CI) 1.41-22.22], cumulative use of antibiotics exceeding 1 week during the previous year (OR 4.63, 95% CI 1.47-14.54) and methicillin resistance (OR 6.35, 95% CI 1.38-29.15).


CONCLUSIONS
Results suggest that antimicrobial selective pressure and microbial cross-transmission are involved in PRSA acquisition.
Verneuil
L
L
Service de Dermatologie, CHU Caen, F-14033 Caen, France. verneuil-l@chu-caen.fr
Marchand
C
C
Vidal
J S
JS
Ze Bekolo
R
R
Daurel
C
C
Lebouvier
G
G
Leroy
D
D
Leclercq
R
R
D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016022:Case-Control Studies; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005838:Genotype; D006801:Humans; D016015:Logistic Models; D008297:Male; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D025762:Pristinamycin / Q000627:therapeutic use*; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology*; D013207:Staphylococcal Skin Infections / Q000188:drug therapy / Q000453:epidemiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D025762:Pristinamycin