Background: Bacteria especially Gram-negative (GN) are worldwide critical public health trouble, owing to their high antibiotic resistance, along with a shortfall of new active antimicrobial agents. This led to reconsideration of Colistin, as a drug of last hope for these resistant infections. Colistin re-use has provoked the development of Colistin resistance. Mobile-Colistin-resistance (mcr) genes mediated by plasmid have been reported. Screening of these Colistin resistant isolates (CRIs) and their resistant genes will assist in exploring the cause and level of Colistin resistance in Egypt.
Objectives: Isolation and identification of the causative Gram-negative bacteria (GNB) from different infections in hospitals, determination of their antibiotic susceptibility pattern as well as Colistin susceptibility, and examination of the existence of mcr-1 to mcr-5 genes in acquired CRIs.
Methodology: Specimens were collected from 284 immunocompromised patients from urine, sputum, blood, and wound swaps. Isolation and identification of the causative isolates were made by different microbiological procedures. Antibiotic susceptibility pattern was made by the Kirby-Bauer method, while broth microdilution method was used to determine Colistin susceptibility. Lastly, mcr genes were detected in acquired CRIs using multiplex polymerase chain reaction (PCR).
Results: 270 GN isolates were isolated from 284 clinical specimens, Klebsiella pneumoniae was the highest frequent GN isolate with 147 (54.44%) isolates. The highest pattern of resistance was detected toward ceftazidime. Acquired CRIs was detected in 11 (4%) of the isolates, these isolates were identified as K. pneumoniae 8 (72.7%) isolates, and Pseudomonas aeruginosa 3 (27.3%) isolates. The mcr-2 gene was detected in 3 out of 11 (27.3%) CRIs. These isolates were P. aeruginosa (one isolate), and K. pneumoniae (2 isolates).
Conclusion: The prevalence of Colistin-resistance in our study still has minimum levels and has not spread to the public yet. Other resistant mechanisms are acquired to be investigated