National survey of molecular epidemiology of Staphylococcus aureus colonization in Belgian cystic fibrosis patients.
OBJECTIVE
Epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) is poorly defined in cystic fibrosis (CF) patients, and S. aureus detection may be hampered by the presence of small colony variants (SCVs). We conducted a multicentre survey to determine the prevalence of S. aureus and MRSA colonization in Belgian CF patients and characterize the phenotype and clonal distribution of their staphylococcal strains.


METHODS
S. aureus isolated from CF patients attending nine CF centres were collected. Oxacillin resistance was detected by oxacillin agar screen and mecA PCR. Antibiotic susceptibility was tested by microdilution. MRSA strains were genotyped by PFGE and SCCmec typing and compared with hospital-associated MRSA strains.


RESULTS
Laboratories used a diversity of sputum culture procedures, many of which appeared substandard. S. aureus was isolated from 275/627 (44%) CF patients (20% to 72% by centre). The prevalence of SCV colonization was 4%, but SCVs were almost exclusively recovered from patients in two centres performing an SCV search. Phenotypically, 14% of S. aureus isolates were oxacillin-resistant: 79% carried mecA and 19% were SCVs lacking mecA. The mean prevalence of 'true' MRSA colonization was 5% (0% to 17% by centre). By PFGE typing, 67% of CF-associated MRSA were related to five epidemic clones widespread in Belgian hospitals.


CONCLUSIONS
This first survey of S. aureus colonization in the Belgian CF population indicated a diversity in local prevalence rates and in proportion of oxacillin-resistant and SCV phenotypes, probably related to variation in bacteriological methods. These findings underscore the need for standard S. aureus detection methods and MRSA control policies in Belgian CF centres.
Vergison
A
A
Department of Pediatric Infectious Diseases, Hospital Epidemiology and Infection Control Unit, Université Libre de Bruxelles, Hôpital des Enfants Reine Fabiola, Brussels, Belgium. anne.vergison@ulb.ac.be
Denis
O
O
Deplano
A
A
Casimir
G
G
Claeys
G
G
DeBaets
F
F
DeBoeck
K
K
Douat
N
N
Franckx
H
H
Gigi
J
J
Ieven
M
M
Knoop
C
C
Lebeque
P
P
Lebrun
F
F
Malfroot
A
A
Paucquay
F
F
Pierard
D
D
Van Eldere
J
J
Struelens
M J
MJ
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001530:Belgium; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D007223:Infant; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017720:Molecular Epidemiology; D010068:Oxacillin / Q000494:pharmacology; D011446:Prospective Studies; D013183:Sputum / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents; D010068:Oxacillin