High Rates of Aminoglycoside Methyltransferases Associated with Metallo-Beta-Lactamases in Multidrug-Resistant and Extensively Drug-Resistant Clinical Isolates from a Tertiary Care Hospital in Egypt.

BACKGROUND

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of are the leading cause of healthcare-associated infections worldwide.

OBJECTIVE

The aim was to identify the resistant phenotypes among and to characterize different aminoglycosides and carbapenem resistance genes as major mechanisms of resistance in these isolates, in Theodor Bilharz Research Institute (TBRI), a tertiary care hospital in Cairo, Egypt.

METHODS

During a period of 11 months, 42 clinical isolates were collected from the microbiology laboratory by routine culture. Antimicrobial sensitivity testing to the aminoglycosides gentamicin and amikacin, and other classes of antibiotics, was performed by a disk diffusion method. Isolates were tested for aminoglycoside resistance genes, , , , , , , and , and carbapenemase resistance genes , , and , using conventional PCR.

RESULTS

Thirty-three (78.5%) of the clinical isolates showed MDR and XDR phenotypes at 42.4% and 57.65%, respectively, and these were included in the study. Aminoglycoside resistance was found in 97%, whereas carbapenem resistance was found in 81% of the isolates phenotypically. Only 59.4% (19/26) of the aminoglycoside-resistant isolates harbored resistance genes; none of the amikacin-susceptible isolates harbored any of the tested aminoglycoside resistance genes. Aminoglycoside resistance genes , , , and were found at rates of 17/33 (51.5%), 3/33 (9%), 2/33 (6%), and 2/33 (6%), respectively, whereas , , and were not detected. Only 40.7% (11/27) of the carbapenem-resistant isolates harbored resistance genes. Carbapenem resistance genes, and , were found at rates of 7/33 (21.2%) and 6/33 (18.1%), respectively, and was not detected.

CONCLUSION

Rates of MDR and XDR and resistance to aminoglycosides and carbapenems in our setting are high. Methyltransferases and metallo-beta-lactamases are the main mechanisms of resistance to aminoglycosides and carbapenems, respectively. The presence of and in the strains confirms their rapid dissemination in the Egyptian environment.