Outbreak of carbapenem-resistant Pseudomonas aeruginosa producing SPM-1 metallo-{beta}-lactamase in a teaching hospital in southern Brazil.
OBJECTIVE
To describe the first nosocomial outbreak of Pseudomonas aeruginosa producing SPM-1 metallo-beta-lactamase (MBL) in southern Brazil.


METHODS
From January to October 2004, carbapenem-resistant P. aeruginosa (CRPA) were recovered from hospitalized patients. Mortality, site of infection/colonization, patient location and susceptibility profiles were analysed. A sample of CRPA was screened for MBL production, evaluated for the presence of bla(SPM-1), bla(IMP-1) and bla(VIM-2) genes by PCR and submitted for molecular typing by DNA macrorestriction.


RESULTS
A total of 135 CRPA (one isolate per patient) were recovered. Two major antibiotic susceptibility profiles comprised 63.7% of the isolates (susceptibility to polymyxin B and aztreonam, and susceptibility only to polymyxin B). Thirty-five CRPA were screened for MBL production (10 isolates from April, June and July, and 25 from September and October) and 27 (77.1%) proved to be positive for MBL production. Twenty-one of the 24 CRPA tested carried the bla(SPM-1) gene. The mortality of patients with CRPA was 48.1% and no variable was associated with death. Molecular typing revealed the presence of a clone with four related subtypes among the bla(SPM-1)-positive CRPA.


CONCLUSIONS
The prevalence of MBL production by CRPA is high and horizontal transmission is a major determinant for the spread of SPM-1 CRPA among patients in this institution. As infection control measures failed to control the spread of CRPA, continuous surveillance for MBL production is warranted.
Zavascki
Alexandre Prehn
AP
Infectious Diseases Service, Hospital São Lucas da Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil. apzavascki@terra.com.br
Gaspareto
Patrick Barcelos
PB
Martins
Andreza Francisco
AF
Gonçalves
Ana Lúcia
AL
Barth
Afonso Luís
AL
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001938:Brazil / Q000453:epidemiology; D015780:Carbapenems / Q000494:pharmacology*; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D004196:Disease Outbreaks; D018562:Disease Transmission, Infectious; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006784:Hospitals, Teaching; D006801:Humans; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D012150:Polymorphism, Restriction Fragment Length; D011552:Pseudomonas Infections / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality / Q000635:transmission; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D000900:Anti-Bacterial Agents; D015780:Carbapenems; D004269:DNA, Bacterial; C476155:beta-lactamase SPM-1, Pseudomonas aeruginosa; D001618:beta-Lactamases