Nosocomial outbreak by imipenem-resistant metallo-beta-lactamase-producing Pseudomonas aeruginosa in an adult intensive care unit in a Brazilian teaching hospital.
OBJECTIVE
To describe an outbreak of imipenem-resistant metallo-beta-lactamase-producing Pseudomonas aeruginosa, enzyme type bla, by horizontal transmission in patients admitted to a mixed adult ICU.


METHODS
A case-control study was carried out, including 47 patients (cases) and 122 patients (control) admitted to the mixed ICU of a university hospital in Minas Gerais, Brazil from November 2003 to July 2005. The infection site, risk factors, mortality, antibiotic susceptibility, metallo-beta-lactamase (MBL) production, enzyme type, and clonal diversity were analyzed.


RESULTS
A temporal/spatial relationship was detected in most patients (94%), overall mortality was 55.3%, and pneumonia was the predominant infection (85%). The majority of isolates (95%) were resistant to imipenem and other antibiotics, except for polymyxin, and showed MBL production (76.7%). Only bla SPM-1 (33%) was identified in the 15 specimens analyzed. In addition, 4 clones were identified, with a predominance of clone A (61.5%) and B (23.1%). On multivariate analysis, advanced age, mechanical ventilation, tracheostomy, and previous imipenem use were significant risk factors for imipenem-resistant P. aeruginosa infection.


CONCLUSIONS
Clonal dissemination of MBL-producing P. aeruginosa strains with a spatial/temporal relationship disclosed problems in the practice of hospital infection control, low adherence to hand hygiene, and empirical antibiotic use.
Cezário
Renata Cristina
RC
Area Immunology, Parasitology and Microbiology at Universidade Federal de Uberlândia, Uberlândia-Minas Gerais, Brazil. cezariorenata@yahoo.com
Duarte De Morais
Lea
L
Ferreira
Joseane Cristina
JC
Costa-Pinto
Rogério M
RM
da Costa Darini
Ana Lúcia
AL
Gontijo-Filho
Paulo P
PP
D001938:Brazil; D016022:Case-Control Studies; D003428:Cross Infection / Q000453:epidemiology*; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011552:Pseudomonas Infections / Q000453:epidemiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology*; D001618:beta-Lactamases / Q000096:biosynthesis*
D015378:Imipenem; D001618:beta-Lactamases