Diversity of Molecular Mechanisms Conferring Carbapenem Resistance to Pseudomonas aeruginosa Isolates from Saudi Arabia.
Background. This study described various molecular and epidemiological characters determining antibiotic resistance patterns in Pseudomonas aeruginosa isolates. Methods. A total of 34 carbapenem-resistant P. aeruginosa clinical isolates were isolated from samples collected at a tertiary hospital in Riyadh, Saudi Arabia, from January to December 2011. Susceptibility testing, serotyping, molecular characterization of carbapenem resistance, and pulsed-field gel electrophoresis (PFGE) were performed. Results. All isolates were resistant to ceftazidime, and more than half were highly resistant (minimum inhibitory concentration (MIC) > 256 mg/L). Fifteen isolates had MIC values ≥64 mg/L for any of the carbapenems examined. Vietnamese extended-spectrum β-lactamase (VEB-1) (n = 16/34) and oxacillinase (OXA-10) (n = 14/34) were the most prevalent extended-spectrum β-lactamase and penicillinase, respectively. Verona imipenemase (VIM-1, VIM-2, VIM-4, VIM-11, and VIM-28) and imipenemase (IMP-7) variants were found in metallo-β-lactamase producers. A decrease in outer membrane porin gene (oprD) expression was seen in nine isolates, and an increase in efflux pump gene (MexAB) expression was detected in five isolates. Six serotypes (O:1, O:4, O:7, O:10, O:11, and O:15) were found among the 34 isolates. The predominant serotype was O:11 (16 isolates), followed by O:15 (nine isolates). PFGE analysis of the 34 carbapenem-resistant P. aeruginosa isolates revealed 14 different pulsotypes. Conclusions. These results revealed diverse mechanisms conferring carbapenem resistance to P. aeruginosa isolates from Saudi Arabia.
Pharmaceutics Department, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia; Microbiology and Immunology Department, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt.
Mohamed H
0000-0001-9868-0355
MH
Al-Agamy
Laboratoire de Bactériologie, Centre National de Référence de la Résistance aux Antibiotiques, Besançon, France; Unité des Agents Antimicrobiens, Institut Pasteur, Paris, France.
Katy
K
Jeannot
Microbiology and Immunology Department, Faculty of Pharmacy, Helwan University, Cairo, Egypt.
Taghrid S
TS
El-Mahdy
Microbiology and Immunology Department, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt; College of Pharmacy, Al Baha University, Al Baha, Saudi Arabia.
Hassan A
HA
Samaha
Pharmaceutics Department, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia; College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
Atef M
AM
Shibl
Laboratoire de Bactériologie, Centre National de Référence de la Résistance aux Antibiotiques, Besançon, France.
Patrick
P
Plésiat
Unité des Agents Antimicrobiens, Institut Pasteur, Paris, France.
Patrice
P
Courvalin