Dissemination and diversity of metallo-β-lactamases in Latin America: report from the SENTRY Antimicrobial Surveillance Program

Molecular evolution of metallo-beta-lactamase-producing Pseudomonas aeruginosa in a nosocomial setting of high-level endemicity

An outbreak of multidrug-resistant Pseudomonas aeruginosa strains producing VIM-type metallo-beta-lactamases (MBLs) has occurred in an Italian hospital since 2000 (C. Lagatolla, E. A. Tonin, C. Monti-Bragadin, L. Dolzani, F. Gombac, C. Bearzi, E. Edalucci, F. Gionechetti, and G. M. Rossolini, Emerg. Infect. Dis. 10:535-538, 2004). In this work, using molecular methods, we characterized 128 carbapenem-resistant isolates (including 98 VIM-positive isolates) collected from that hospital from 2000 to 2002 to investigate the dynamics of the dissemination of MBL producers in the clinical setting. Genotyping by random amplification of polymorphic DNA and pulsed-field gel electrophoresis showed that most VIM-positive isolates belonged to two different clonal lineages, producing either a VIM-1- or a VIM-2-like MBL, whose ancestors were detected for the first time in the hospital in 1999, suggesting that clonal expansion played a predominant role in the dissemination of these isolates. The 86 clonally related isolates carrying a blaVIM-1-like gene on an In70-like integron were clearly related to a VIM-1-positive P. aeruginosa clone circulating in various Italian hospitals since the late 1990s. VIM-negative P. aeruginosa strains related to the VIM-1-positive clone were detected during the same period, suggesting that the latter strain was derived from a clonal lineage already circulating in the hospital. In the VIM-2-like positive clone, the MBL gene was carried by an unusual class 1 integron, named In71, lacking the 3' conserved sequence region typical of sul1-associated integrons. A different class 1 integron with an original structure carrying a blaVIM-2 determinant, named In74, was detected in a sporadic isolate. A retrospective investigation did not reveal the presence of strains related to any of the VIM-producing isolates earlier than 1997.

Characterization of an epidemic carbapenem-resistant Pseudomonas aeruginosa producing SPM-1 metallo-beta-lactamase in a hospital located in Rio de Janeiro, Brazil

Metallo-beta-lactamase production is emerging worldwide as an important mechanism of carbapenem resistance among nonfermentative Gram-negative isolates, and this mechanism is becoming frequently observed in Brazil. This study documents the occurrence and characteristics of an epidemic SPM-1-producing Pseudomonas aeruginosa strain in a teaching hospital located in Rio de Janeiro City, Brazil. The bla (SPM-1) gene and a class 1 integron were detected in 13 isolates, representing 20% of the 65 imipenem-resistant P. aeruginosa isolates obtained from January, 2000, to August, 2001. DNA sequencing revealed that this integron carries three gene cassettes that confer resistance to antimicrobials, aacA4, bla (OXA-56), and aadA7, and an orf1 encoding a putative transposase. All 13 SPM-producing P. aeruginosa isolates had closely related pulsed-field gel electrophoresis (PFGE) profiles, designated as clonal group A, suggesting nosocomial spread of the strain. This clonal group was the same as that observed in other SPM-1-producing P. aeruginosa isolates from distinct Brazilian states. The dissemination of this clone throughout Brazil could not be explained by transfer of infected patients and/or sharing of common health-care staff. It is likely that the spread of these strains occurred indirectly via the community.

What Infection Control Interventions Should Be Undertaken to Control Multidrug-Resistant Gram-Negative Bacteria?

Multidrug-resistant gram-negative bacteria are an emerging problem. The present article addresses 2 relevant questions: (1) should active surveillance be performed to identify patients colonized with multidrug-resistant gram-negative bacteria, and (2) should contact isolation precautions be taken with patients colonized or infected with multidrug-resistant gram-negative bacteria? Data and variables that are needed to scientifically answer these questions are reviewed, as are existing data on Pseudomonas aeruginosa, Enterobacteriaceae (Escherichia coli and Klebsiella species in particular), and Acinetobacter baumannii.

Activity of meropenem and comparators against Pseudomonas aeruginosa and Acinetobacter spp. isolated in the MYSTIC Program, 2002-2004

This study examines the susceptibilities of meropenem and other broad-spectrum antimicrobials tested against bacterial isolates collected from hospitalized patients during 2002-2004 from worldwide medical centers participating in the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program. The in vitro activity of meropenem and 5 comparator antimicrobial agents was assessed against Pseudomonas aeruginosa and Acinetobacter spp. Generally, the susceptibility of Australasian and North American isolates was higher than that of the European and South American isolates. The rank order of activity of the antimicrobial agents tested against a worldwide collection of P. aeruginosa was piperacillin/tazobactam (77.7% susceptible) > meropenem (75.4%) > ceftazidime (70.0%) > imipenem (69.7%) > gentamicin (66.1%) > ciprofloxacin (62.0%). Against a worldwide collection of Acinetobacter spp. meropenem (76.1% susceptible) was the most active compound followed by imipenem (74.7%) > gentamicin (51.9%) > ciprofloxacin (40.5%) > piperacillin/tazobactam (39.8%) > ceftazidime (38.1%). The carbapenems appear to be a valuable option for the treatment of serious nosocomial infections caused by P. aeruginosa or Acinetobacter spp. over a broad geographical region.

An overview of the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program: 1997-2004

This overview provides a summary of the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program over an 8-year period from 1997 to 2004. The evolution of the MYSTIC Program is described, as well as its design compared with other surveillance programs. In addition, the global MYSTIC Program data, published to date, are summarized, and the empiric use of carbapenems, their current indications, and meropenem usage versus resistance was discussed. From 1997 to 2004, 120 medical centers that were actively prescribing meropenem in 32 countries worldwide participated in the program. The MYSTIC Program results demonstrate the sustained potency and continued effectiveness of meropenem globally against clinically relevant Gram-negative and Gram-positive pathogens including extended spectrum beta-lactamase- and AmpC beta-lactamase-producing organisms, which may also display resistance to the fluoroquinolones and/or aminoglycosides. Furthermore, in centers actively prescribing meropenem, resistance to meropenem is not increasing despite greater resistance among the comparator antimicrobial agents. Thus, antipseudomonal carbapenems such as meropenem and imipenem remain an effective treatment option.

Prévalence des souches d'Acinetobacter baumannii et de Pseudomonas aeruginosa résistantes à l'imipénème par production de métallo-β-lactamases

Metallo-beta-lactamases (MBL) are enzymes produced by Gram-negative bacilli such as Pseudomonas aeruginosa and Acinetobacter baumannii. These enzymes make these isolates resistant to imipenem.

AIM

The aim of this study was to determine the prevalence of this resistance mechanism in Pseudomonas aeruginosa and Acinetobacter baumannii strains identified in the bacteriology laboratory of the Rabat Ibn Sina teaching hospital, Morocco.

MATERIALS AND METHOD

Screening for MBL was systematic in all resistant strains and/or strains with decreased sensitivity to imipenem, according to Dongeun Yong et al.'s method, using a sterilized solution of EDTA 0.5 M pH 8.

RESULTS

Eighty-five bacterial strains (48 P. aeruginosa and 37 A. baumannii) were identified 23% (11) and 57% (21) of which were respectively resistant to the imipenem. The prevalence of MbetaL producing strains was 27% for P. aeruginosa and 38% for A. baumannii.

CONCLUSION

These results show that the frequency of these strains is increases in our hospital and that their emergence represents a serious therapeutic and epidemiological problem. This means that we need to implement the supervision of hospital microbial environment and strictly apply hygiene measures.

Dissemination of IMP-1 metallo- beta -lactamase-producing Acinetobacter species in a Brazilian teaching hospital

OBJECTIVE

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

DESIGN

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

SETTING

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

METHODS

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 bla(IMP), bla(VIM), and bla(SPM), followed by gene sequencing. Genetic similarity among the carbapenem-resistant strains was evaluated by automated ribotyping.

RESULTS

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 bla(IMP-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 bla(VIM) or bla(SPM) 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.

CONCLUSIONS

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.

First detection of metallo-beta-lactamase VIM-2 in Pseudomonas aeruginosa isolates from Colombia

Carbapenem resistance rates in Pseudomonas aeruginosa isolates in Colombia, as in many South American countries, are high for reasons that remain unclear. From our nationwide network, we describe the first detection of the metallo-beta-lactamase VIM-2 in clinical isolates of P. aeruginosa from multiple cities within Colombia. Metallo-beta-lactamases were not detected in the two centers with the highest imipenem resistance rates. Clonality was noted in five of the eight centers with strains meeting the criteria for molecular typing. The high carbapenem resistance in P. aeruginosa in Colombia may be attributable to a combination of factors, including the presence of metallo-beta-lactamases and nosocomial transmission.

Genetic and enzymatic properties of metallo-beta-lactamase VIM-5 from a clinical isolate of Enterobacter cloacae

A VIM-5-producing Enterobacter cloacae isolate (EDV/1) was identified in a collection of clinical strains stored before 2002. The gene, bla(VIM-5), was located on a 2,712-bp BamHI-HindIII fragment of a 23-kbp (approximately) nonconjugative plasmid (pEDV5) in a class 1 integron as a single gene cassette.

Regional occurrence of plasmid-mediated carbapenem-hydrolyzing oxacillinase OXA-58 in Acinetobacter spp. in Europe

The spread of the plasmid-mediated carbapenem-hydrolyzing oxacillinase OXA-58 was detected in Acinetobacter sp. clinical isolates from southern Europe, the Balkans, and central Turkey. It may contribute significantly to the emergence of carbapenem resistance in Acinetobacter spp., at least in this part of the world.

First nosocomial outbreak of Pseudomonas aeruginosa producing an integron-borne metallo-beta-lactamase (VIM-2) in the United States

Carbapenemases are rare in the United States. This is the first report of a United States nosocomial outbreak of pan-resistant Pseudomonas aeruginosa infections due to an integron-borne metallo-beta-lactamase, VIM-2. This emergence of carbapenemases on mobile genetic elements in the United States warrants surveillance.

Emerging Metallo‐β‐Lactamase–Mediated Resistances: A Summary Report from the Worldwide SENTRY Antimicrobial Surveillance Program

The rates of occurrence of metallo-beta-lactamase-mediated resistances in Pseudomonas aeruginosa, Acinetobacter species, and Serratia marcescens, among other gram-negative bacilli, have escalated since 2000, severely limiting treatment options in Asia, Europe, and Latin America to non-beta-lactam antimicrobial classes. Clinical isolates harboring metallo-beta-lactamases have also recently been reported in western Canada and in Texas, signaling the need for development of accurate diagnostic tests by clinical laboratories to detect their presence and for new, and more potent, antimicrobial agents.