Molecular epidemiology and risk factors of bloodstream infections caused by extended-spectrum beta-lactamase-producing Klebsiella pneumoniae A case-control study.
OBJECTIVE
To study the prevalence, risk factors, outcome, and molecular epidemiology in patients with bacteremia caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae (Kp) (cases), in comparison with patients with bacteremia caused by a susceptible Kp (controls).


METHODS
This was a retrospective case-control study including all episodes of Kp bacteremia for the period 1993 to 2002 at a referral hospital for adults in Mexico. ESBL production was tested for by E-test. All isolates were typed by pulsed field gel electrophoresis (PFGE). A subset of isolates underwent plasmid analysis, conjugal transfer of cefotaxime resistance to Escherichia coli J53-2, isoelectric focusing bioassay, colony-blot hybridization, PCR, and sequencing.


RESULTS
Of the 121 patients with bacteremia due to Kp included in the study, 17 (14.0%) had an ESBL-Kp isolate (cases). Multivariate analysis identified prior use of cephalosporins (OR 7.6, 95% CI 1.1-53.5; p=0.039) and stay in the intensive care unit (ICU; OR 5.6, 95% CI 1.1-27.9; p=0.033) as significant risk factors. No differences were observed in hospital stay or mortality after the event. Multi-drug resistance was more frequent in ESBL-Kp. There was no clonal predominance. A distinct beta-lactamase profile was identified, which included a combination of TEM-1 (pI 5.4) and SHV-5 (pI 8.2) in 13/17 ESBL-Kp isolates. Cefotaxime resistance was transferred by conjugation in 14/17 isolates with a >120-kb plasmid encoding ESBL.


CONCLUSIONS
The prevalence of ESBL-Kp was found to be lower than that previously reported in Latin America. ESBL-Kp bacteremia was not associated with a worse clinical outcome. We were able to identify a plasmid-mediated horizontal dissemination over the 10-year period.
School of Medicine, University of Guanajuato, Leon, Guanajuato, Mexico.
Juan L
JL
Mosqueda-Gómez
Aldo
A
Montaño-Loza
Ana L
AL
Rolón
Carlos
C
Cervantes
J Miriam
JM
Bobadilla-del-Valle
Jesús
J
Silva-Sánchez
Ulises
U
Garza-Ramos
Angelina
A
Villasís-Keever
Arturo
A
Galindo-Fraga
Guillermo M Ruiz
GM
Palacios
Alfredo
A
Ponce-de-León
José
J
Sifuentes-Osornio
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017720:Molecular Epidemiology; D015995:Prevalence; D012307:Risk Factors; D055815:Young Adult; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D000900:Anti-Bacterial Agents; C117193:beta-lactamase SHV-5; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1