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Dissemination of IMP-1 Metallo-β-Lactamase–Producing Acinetobacter Species in a Brazilian Teaching Hospital

  • Maria C. B. Tognim (a1) (a2), Ana C. Gales (a1), Andréia P. Penteado (a1), Suzane Silbert (a1) and Hélio S. Sader (a1) (a2)...



To evaluate the emergence and dissemination of metallo-β-lactamase (MBL)–producing Acinetobacter species.


All carbapenem-resistant Acinetobacter strains (1 strain per patient) collected during the period 1993–2001 were evaluated.


A Brazilian tertiary care teaching hospital (Hospital São Paulo, São Paulo).


Seventy-three strains of carbapenem-resistant Acinetobacter species were recovered from the organism bank of the hospital. All isolates were tested for antimicrobial susceptibility by broth microdilution methods, and the production of MBL was initially assessed by phenotypic tests (MBL Etest strip and a disk approximation test). The MBL enzymes were identified by polymerase chain reaction using primers for blaIMP’, blaVIM’, and blaSPM’ followed by gene sequencing. Genetic similarity among the carbapenem-resistant strains was evaluated by automated ribotyping.


Only colistin and ampicillin-sulbactam showed reasonable in vitro activity against carbapenem-resistant isolates (97% and 74% of isolates susceptible, respectively). More than half of the isolates (55%) had a positive MBL phenotypic test result and a positive polymerase chain reaction result for blaIMP_1 The proportion of IMP-1–producing Acinetobacter isolates among carbapenem-resistant strains increased from 0% in the 1993-1997 period to 29% in 1998 and 100% in the 1999-2001 period. No carbapenem-resistant Acinetobacter isolates that harbored blaVIM or blaSPM were detected. Molecular typing results revealed 20 ribogroups among carbapenem-resistant isolates. During the study period of 1994-2001, we identified 2 major ribogroups, 52-1 (MBL-negative and MBL-positive strains) and 60-7 (MBL-positive strains), that had a coefficient of similarity of 0.85 or higher.


Our results indicate that IMP-1–producing strains of Acinetobacter emerged in our institution in 1998. Since then, production of this MBL was detected not only in the major ribogroups of carbapenem-resistant Acinetobacter species but also among isolates that belonged to 17 distinct ribogroups, indicating that this important mechanism of antimicrobial resistance was disseminated among distinct clones.


Corresponding author

JMI Laboratories, 345 Beaver Kreek Centre, Suite A, North Liberty, Iowa 52317 (


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1.Quale, J, Bratu, S, Landman, D, et al. Molecular epidemiology and mechanisms of carbapenem resistance in Acinetobacter baumannii endemic in New York City. Clin Infect Dis 2003; 37:214220.
2.Smolyakov, R, Borer, A, Riesenberg, K, et al. Nosocomial multi-drug resistant Acinetobacter baumannii bloodstream infection: risk factors and outcome with ampicillin-sulbactam treatment. J Hosp Infect 2003; 54:3238.
3.Livermore, DM. The impact of carbapenemases on antimicrobial development and therapy. Curr Opin Investig Drugs 2002; 3:218224.
4.Toleman, MA, Simm, AM, Murphy, TA, et al. Molecular characterization of SPM-1, a novel metallo-beta-lactamase isolated in Latin America: report from the SENTRY antimicrobial surveillance programme. J Antimicrob Chemother 2002; 50:673679.
5.Castanheira, M, Toleman, MA, Jones, RN, Schimitz, F-J, Walsh, TR. Molecular characterization of a β-lactamase gene, bla GIM-1 a new subclass of metallo-β-lactamase: report from the SENTRY Antimicrobial Surveillance Program. Antimicrob Agents Chemother 2004; 48:46544661.
6.Gales, AC, Tognim, MC, Reis, AO, et al. Emergence of an IMP-like metalloenzyme in an Acinetobacter baumannii clinical strain from a Brazilian teaching hospital. Diagn Microbiol Infect Dis 2003; 45:7779.
7.National Committee for Clinical Laboratory Standards (NCCLS). Performance Standards for Antimicrobial Disk Susceptibility Tests: Approved Standard M2-A8. 8th ed. Wayne, PA: National Committee for Clinical Laboratory Standards; 2003.
8.National Committee for Clinical Laboratory Standards (NCCLS). Approved Standard M7-A6: Methods for Dilution Antimicrobial Susceptibility Test for Bacteria That Grow Aerobically. 6th ed. Wayne, PA: National Committee for Clinical Laboratory Standards; 2003.
9.National Committee for Clinical Laboratory Standards (NCCLS). Performance Standards for Antimicrobial Susceptibility Testing, 15th Information Supplement M100-S15. Wayne, PA: National Committee for Clinical Laboratory Standards; 2003.
10.Walsh, TR, Bolmstrom, A, Qwarnstrom, A, Gales, AC. Evaluation of a new Etest for detecting metallo-beta-lactamases in routine clinical testing. J Clin Microbiol 2002; 40:27552759.
11.Hollis, RJ, Bruce, JL, Fritschel, SJ, et al. Comparative evaluation of an automated ribotyping instrument versus pulsed-field gel electrophoresis for epidemiological investigation of clinical isolates of bacteria. Diagn Microbiol Infect Dis 1999; 34:263268.
12.Levin, AS, Barone, AA, Penco, J, et al. Intravenous Colistin as therapy for nosocomial infections caused by multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii. Clin Infect Dis 1999; 28:10081011.
13.Sader, S, Castanheira, M, Mendes, RE, Toleman, M, Walsh, TR, Jones, RN. Dissemination and diversity of metallo-β-lactamases in Latin America: report from the SENTRY Antimicrobial Surveillance Program. Int J Antimicrob Agents 2005; 25:5761.


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