Antimicrobial resistance, virulence factors and genetic lineages of hospital-onset methicillin-resistant Staphylococcus aureus isolates detected in a hospital in Zaragoza.
BACKGROUND
MRSA population dynamics is undergoing significant changes, and for this reason it is important to know which clones are circulating in our nosocomial environment.


METHODS
A total of 118 MRSA isolates were collected from clinical samples from patients with previous hospital or healthcare contact (named as hospital-onset MRSA (HO-MRSA)) during a one year period. Susceptibility testing was performed by disk diffusion and microdilution. The presence of resistance genes and virulence factors were tested by PCR. All isolates were typed by SCCmec, spa and agr typing. PFGE and MLST were applied to a selection of them.


RESULTS
Eighty-three HO-MRSA isolates (70.3%) were resistant to any antibiotic included in the macrolide-lincosamide-streptogramin B group. Among these isolates, the M phenotype was the most frequent (73.5%). One hundred and seven of HO-MRSA isolates (90.7%) showed aminoglycoside resistance. The combination aac(6')-Ie-aph(2″)-Ia+ant(4')-Ia genes was the most frequent (22.4%). Tetracycline resistance rates in HO-MRSA isolates were low (3.4%), although a high level of mupirocin resistance was observed (25.4%). Most of the HO-MRSA isolates (approximately 90%) showed SCCmec type IVc and agr type II. Fifteen unrelated pulsotypes were identified. CC5 was the most prevalent (88.1%), followed by CC8 (5.9%), CC22 (2.5%), CC398 (2.5%) and CC1 (0.8%).


CONCLUSIONS
CC5/ST125/t067 lineage was the most frequent. This lineage was related to aminoglycoside resistance, and to a lesser extent, with macrolide resistance. The presence of international clones as EMRSA-15 (CC22/ST22), European clones as CC5/ST228, community clones related to CC1 or CC8 and livestock associated clones, as CC398, were observed in a low percentage.
Servicio de Microbiología, Hospital Clínico Universitario Lozano Blesa, San Juan Bosco s/n, Zaragoza, Spain.
María
M
González-Domínguez
Servicio de Microbiología, Hospital Clínico Universitario Lozano Blesa y Departamento de Microbiología, Facultad de Medicina, Universidad de Zaragoza, San Juan Bosco s/n, Zaragoza, Spain. Electronic address: cseral@unizar.es.
Cristina
C
Seral
Servicio de Microbiología y Unidad de Apoyo a la Investigación, Instituto de Investigación Biomédica de Vigo (IBIV), Complexo Hospitalario Universitario de Vigo (CHUVI), C/ Pizarro, 22, Vigo, Pontevedra, Spain.
Carmen
C
Potel
Unidad de Apoyo a la Investigación, Instituto de Investigación Biomédica de Vigo (IBIV), Complejo Hospitalario Universitario de Vigo (CHUVI), C/ Pizarro, 22, Vigo, Pontevedra, Spain.
Lucía
L
Constenla
Servicio de Microbiología, Hospital Clínico Universitario Lozano Blesa, San Juan Bosco s/n, Zaragoza, Spain.
Sonia
S
Algarate
Servicio de Microbiología, Hospital Clínico Universitario Lozano Blesa, San Juan Bosco s/n, Zaragoza, Spain.
M José
MJ
Gude
Servicio de Microbiología y Unidad de Apoyo a la Investigación, Instituto de Investigación Biomédica de Vigo (IBIV), Complexo Hospitalario Universitario de Vigo (CHUVI), C/ Pizarro, 22, Vigo, Pontevedra, Spain.
Maximiliano
M
Álvarez
Servicio de Microbiología, Hospital Clínico Universitario Lozano Blesa y Departamento de Microbiología, Facultad de Medicina, Universidad de Zaragoza, San Juan Bosco s/n, Zaragoza, Spain.
Francisco Javier
FJ
Castillo
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D002648:Child; D002675:Child, Preschool; D002999:Clone Cells; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D005260:Female; D005798:Genes, Bacterial; D006801:Humans; D007223:Infant; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D037521:Virulence Factors / Q000235:genetics; D055815:Young Adult
D000900:Anti-Bacterial Agents; D037521:Virulence Factors
Clonal lineages; Genes de resistencia; Hospital-onset; Líneas clonales; MRSA; Molecular typing; Origen hospitalario; Resistance genes; SARM; Tipado molecular