Stenotrophomonas maltophilia healthcare-associated infections: identification of two main pathogenic genetic backgrounds.
BACKGROUND
Stenotrophomonas maltophilia is an opportunistic multi-drug-resistant bacterium responsible for healthcare-associated infections. Strategies for in-hospital infection control and management of carriers and environmental reservoirs remain controversial.


OBJECTIVE
To determine the population structure of S. maltophilia strains in hospitalized infected patients and to identify putative highly pathogenic subpopulations that require upgraded infection control measures.


METHODS
Eighty-three diverse human strains of various clinical origins from 18 geographically distant hospitals were characterized phenotypically and genotypically using a multi-locus sequence typing (MLST) approach.


RESULTS
Neither a predominant nor emerging sequence type (ST) was identified. Among the 80 typeable strains, only 29% corresponded to described STs, especially ST5 (N=6) and ST4/26/31 (N=2). The ST distribution and the phylogenic tree based on the concatenated MLST genes did not account for geographical, clinical origin or antimicrobial susceptibility clustering. A phylogenic tree that included 173 ST profiles from the MLST database and the 80 typeable strains confirmed the high genetic diversity of S. maltophilia, the previously reported genogroup organization and the predominance of genogroup 6, as it represented 41% (33/80) of the strains. Unexpectedly, genogroup 2 was the second most prevalent genogroup and included 16% (13/80) of the strains. These genogroups represented 57% (20/35) of the strains in respiratory patients and 75% (9/12) of the strains in patients with cystic fibrosis.


CONCLUSIONS
Beyond MLST, the over-representation of some genogroups among strains responsible for healthcare-associated infections was confirmed. Genogrouping affiliation is recommended to implement infection control measures selectively for the most pathogenic strains isolated from patient or environmental reservoirs.
Laboratory of Bacteriology, Department of Microbiology, University Hospital Henri Mondor, Créteil, France.
C
C
Corlouer
Department of Bacteriology, Archet 2 Hospital, Nice Academic Hospital, Nice, France.
B
B
Lamy
Laboratory of Bacteriology, Department of Microbiology, University Hospital Henri Mondor, Créteil, France; University Paris East Créteil, Créteil, France.
M
M
Desroches
Department of Microbiology, Marqués de Valdecilla University Hospital and IDIVAL Research Institute, Santander, Cantabria, Spain.
J
J
Ramos-Vivas
Laboratory of Bacteriology, Abderahman MAMI Pneumo-Phthisiology Hospital, Tunis, Tunisia.
E
E
Mehiri-Zghal
Laboratory of Bacteriology, Saint Nazaire Hospital, Saint Nazaire, France.
O
O
Lemenand
Laboratory of Bacteriology, Emile Muller Hospital, Mulhouse, France.
J-M
JM
Delarbre
Laboratory of Bacteriology, Department of Microbiology, University Hospital Henri Mondor, Créteil, France; University Paris East Créteil, Créteil, France. Electronic address: jean-winoc.decousser@hmn.aphp.fr.
J-W
JW
Decousser
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D005838:Genotype; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D010641:Phenotype; D020615:Stenotrophomonas maltophilia / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D055815:Young Adult
Genogroup; MLST; Nosocomial; Stenotrophomonas maltophilia