MECHANISMS OF RESISTANCE TO AMINOGLYCOSIDES AND FLUOROQUINOLONES IN Acinetobacter baumannii CLINICAL ISOLATES IN LGERIAN HOSPITALS

Abstract

The aim of the present study was to identify antibiotic resistance encoding genes in 71 multidrug resistant A. baumannii isolates. Antibiotic susceptibility testing was performed by the disk diffusion method as well as Etest method. Presence of antibiotic resistance genes that are involved in aminoglycoside and fluoroquinolone resistance were screened by PCR amplification and sequencing. The resistance rates were very high among the 71 A. baumannii for aminoglycosides (22 to 80%) and fluoroquinolones (>90%). Antibiotic resistance encoding genes detected were as follows : aph(3’)-VI (50.7 %), aadA (63.4%), ant(2’’)-I (14.1%), aac(3)-Ia (91.1%) and aac(6’)-Ib (4.2% ). Resistance to ciprofloxacin was due either to mutation Ser83Leu in gyrA (94.4%) or to double mutations Ser83Leu and Ser80Leu (or Ser84Leu ) in gyrA and parC (69.0%), respectively. In conclusion, we show that clinical isolates of A. baumannii recovered in Algerian hospitals present a high level of resistance to antimicrobial agents and harbor many kinds of antibiotic resistance encoding genes.