Risk factors associated with extended-spectrum β-lactamase-producing Enterobacteriaceae nosocomial bloodstream infections in a tertiary care hospital: a clinical and molecular analysis.
OBJECTIVE
To describe the risk factors and molecular epidemiology of nosocomial bloodstream infections caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in a tertiary care hospital.


METHODS
Patients with enterobacteria-positive blood cultures were included. ESBL expression in the isolates was detected using the combination disk method. Antimicrobial susceptibility testing was performed using the disk diffusion method. bla(SHV), bla(TEM), and bla(CTX-M) genes were identified in the isolated strains by PCR and sequencing. Klebsiella pneumoniae isolates were genotyped by PFGE.


RESULTS
Of the 90 isolates recovered, half were found to express ESBLs. Twenty-eight (62%) of these isolates were K. pneumoniae, 8 (18%) were Escherichia coli, 6 (13%) were Enterobacter cloacae, and 3 (7%) were Serratia marcescens. Multivariate logistic regression analysis showed that the only independent risk factor associated with infection by ESBL-producing strains was use of broad-spectrum cephalosporins. None of the isolates was resistant to imipenem. The bla(SHV5) gene was detected in 84% of isolates, followed by bla(CTX-M15) (27%), bla(SHV2) (9%), and bla(SHV12) (7%). PFGE identified six clones among the 28 ESBL-producing K. pneumoniae isolates.


CONCLUSIONS
ESBL-producing K. pneumoniae clones were detected throughout the hospital. Use of broad-spectrum cephalosporins is the most important risk factor associated with the proliferation of ESBL-producing strains.
Servicio de Infectología, Hospital Universitario Dr. José Eleuterio González, Monterrey, Mexico.
Sissy
S
Muro
Elvira
E
Garza-González
Adrian
A
Camacho-Ortiz
Gloria María
GM
González
Jorge Martín
JM
Llaca-Díaz
Francisco
F
Bosques
Félix
F
Rositas
D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis; D052978:Disk Diffusion Antimicrobial Tests; D016521:Electrophoresis, Gel, Pulsed-Field; D016972:Enterobacter cloacae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D005838:Genotype; D006761:Hospitals; D006801:Humans; D007223:Infant; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D012706:Serratia marcescens / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D063128:Tertiary Health Care; D055815:Young Adult; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics*
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004269:DNA, Bacterial; D001618:beta-Lactamases