Susceptibilities to carbapenems and presence of cphA gene on food-borne Aeromonas

ABSTRACT The purpose of this study was to determine the susceptibilities of food-borne Aeromonas to carbapenems, as well as to investigate the presence of a metallo carbapenemase-encoding gene, named cphA. Minimum Inhibitory Concentration (MIC) was determined following NCCLS standards. All the tested microorganisms were susceptible to imipenem, meropenem and biapenem. However, a strong inoculum size effect on carbapenem MICs was observed for most of the strains. Six strains, out of seven, showed the presence of metallo--β−lactamases but cphA gene was detected in only two strains of A. veronii bv. sobria . Key words: metallocarbapenemase, cphA gene, food borne Aeromonas . * Author for correspondence INTRODUCTION Evolution of bacterial resistance to antibiotics in humans, animals and the environment is the result of the interaction between the exposure to antibiotics, selection of microorganisms carrying primordial genes of resistance, and transmission of resistance genes between bacteria. Selective effects occur in selective compartments, where particular antibiotic concentrations result in a differential growth rate of resistant bacterial variants (Baquero et al., 1998) This may happen even at very low antibiotic concentrations able to select low-level-resistant bacteria. Analysis of selective environment-related antibiotic-host-bacteria interactions is essential to understand the biology of antibiotic resistance. (Baquero et al., 1998) To anticipate emergence of resistance, it is necessary to better understand the genetics and biochemistry of resistance mechanisms and to develop methodologies to foresee their evolution at the individual or population level (Baquero et al., 1998). Most retrospective and prospective studies show that after the introduction of an antibiotic, the level of resistance increases both among pathogenic bacteria and in commensal bacteria (van den Bogaard and Stobberingh, 2000). Moreover, commensal bacteria constitute a reservoir of resistance genes for (potentially) pathogenic bacteria. Their level of resistance is considered to be a good indicator for selection pressure by antibiotic use and for resistance problems to be expected in pathogens. Aeromonas strains have been found to be able to produce up to three different β-lactamases

[1]  W. J. Warren,et al.  Population patterns and antimicrobial resistance of Aeromonas in urban playa lakes. , 2004, Canadian journal of microbiology.

[2]  J. Frère,et al.  Biochemical Characterization of the FEZ-1 Metallo-β-Lactamase of Legionella gormanii ATCC 33297T Produced in Escherichia coli , 2001, Antimicrobial Agents and Chemotherapy.

[3]  M. Thaller,et al.  Metallo-β-Lactamase Producers in Environmental Microbiota: New Molecular Class B Enzyme inJanthinobacterium lividum , 2001, Antimicrobial Agents and Chemotherapy.

[4]  E. Stobberingh,et al.  Epidemiology of resistance to antibiotics. Links between animals and humans. , 2000, International journal of antimicrobial agents.

[5]  F. Aarestrup Association between the consumption of antimicrobial agents in animal husbandry and the occurrence of resistant bacteria among food animals , 1999 .

[6]  Gianfranco Amicosante,et al.  Structure of In31, ablaIMP-Containing Pseudomonas aeruginosa Integron Phyletically Related to In5, Which Carries an Unusual Array of Gene Cassettes , 1999, Antimicrobial Agents and Chemotherapy.

[7]  F. Baquero,et al.  Antibiotic-selective environments. , 1998, Clinical infectious diseases : an official publication of the Infectious Diseases Society of America.

[8]  R. Levesque,et al.  Molecular Heterogeneity of the L-1 Metallo-β-Lactamase Family from Stenotrophomonas maltophilia , 1998, Antimicrobial Agents and Chemotherapy.

[9]  B. Berger-Bächi β-Lactam resistance* , 1997 .

[10]  G. Rossolini,et al.  Distribution of cphA or related carbapenemase-encoding genes and production of carbapenemase activity in members of the genus Aeromonas , 1995, Antimicrobial agents and chemotherapy.

[11]  A. MacGowan,et al.  A clinical isolate of Aeromonas sobria with three chromosomally mediated inducible beta-lactamases: a cephalosporinase, a penicillinase and a third enzyme, displaying carbapenemase activity. , 1995, The Journal of antimicrobial chemotherapy.

[12]  S. Amyes,et al.  Three beta-lactamases isolated fromAeromonas salmonicida, including a carbapenemase not detectable by conventional methods , 1994, European Journal of Clinical Microbiology and Infectious Diseases.

[13]  K. Morita,et al.  beta-Lactam resistance of motile Aeromonas isolates from clinical and environmental sources , 1994, Antimicrobial Agents and Chemotherapy.

[14]  F. Yoshimura,et al.  Molecular characterization of an enterobacterial metallo beta-lactamase found in a clinical isolate of Serratia marcescens that shows imipenem resistance , 1994, Antimicrobial Agents and Chemotherapy.

[15]  O. Massidda,et al.  High specificity of cphA-encoded metallo-beta-lactamase from Aeromonas hydrophila AE036 for carbapenems and its contribution to beta-lactam resistance , 1993, Antimicrobial Agents and Chemotherapy.

[16]  O. Massidda,et al.  The Aeromonas hydrophila cphA gene: molecular heterogeneity among class B metallo-beta-lactamases , 1991, Journal of bacteriology.

[17]  H. Bloom,et al.  Aeromonas hydrophila Diarrhea in a Long‐Term Care Setting , 1990, Journal of the American Geriatrics Society.

[18]  M. Anderson,et al.  A note on Aeromonas spp. from chickens as possible food-borne pathogens. , 1990, The Journal of applied bacteriology.

[19]  J. Bakken,et al.  Beta-lactam resistance in Aeromonas spp. caused by inducible beta-lactamases active against penicillins, cephalosporins, and carbapenems , 1988, Antimicrobial Agents and Chemotherapy.

[20]  G. Stelma,et al.  Recovery of Aeromonas hydrophila from Oysters Implicated in an Outbreak of Foodborne Illness. , 1986, Journal of food protection.

[21]  M. Hussain,et al.  Cloning and sequencing of the metallothioprotein beta-lactamase II gene of Bacillus cereus 569/H in Escherichia coli , 1985, Journal of bacteriology.

[22]  E. Bruck,et al.  National Committee for Clinical Laboratory Standards. , 1980, Pediatrics.

[23]  G. Rossolini,et al.  The Aeromonas metallo-beta-lactamases: genetics, enzymology, and contribution to drug resistance. , 1996, Microbial Drug Resistance.

[24]  K. Thomson,et al.  Meropenem: activity against resistant gram-negative bacteria and interactions with beta-lactamases. , 1989, The Journal of antimicrobial chemotherapy.