تأثير بعض المثبطات على الأنزيمات المعدنية المحلِلّة لِلبيتا لاكتَام والمشخصة جينياً لبكتريا الزائفة الزنجارية المعزولة من أخماج جروح الحروق

Effect of Some Inhibitors on Metallo Beta lactamase Genotypically Diagnosed of Pseudomonas aeruginosa Isolated from Burn Wound Infections

Serious burn injury causes damage and skin loss, which is considered as the first line of protector against microbial infections. The opportunistic bacteria including Pseudomonas aeruginosa can invade the body of patient through burn areas and infect it with different diseases that could lead to death.
This study aimed to isolate P. aeruginosa from hospitalized burn patients and test the effectiveness of some inhibitors to combat Metallo Beta-lactamases (MBLs) produce by Pseudomonas aeruginosa, which are responsible for their resistance to the antibiotics.
During the period from December 2021 to April 2022, a total of 249 swabs of burn patients have been collected. All isolates have been diagnosed by culturing on selective media (Cetrimide agar) and confirmed by polymerase chain reaction (PCR) using species specific 16s rDNA for Pseudomonas aeruginosa, 100/249 (40.16%) of swabs have been identified as P. aeruginosa
Antibiotics susceptibility test according to CLSI 2021 have been done to identify the multidrug resistance bacteria (MDR). The results showed 69/100 (69%) were MDR isolates. As a highest records, the response of 81/100 (81%) of isolates were sensitive to cefepime while 83/100 (83%) were resistant to Piperacillin, however this resistance reduced when using Piperacillin/tazobactam to 27/100 (27%).
The resistant patterns of MDR isolates to the antibiotics showed that the more frequently pattern were Piperacillin, Netilmicin, Gentamicin, Ciprofloxacin and Levofloxacin with repetition of 4/69 isolates (5.79%), and the number of isolates that resist to 5 antibiotics recorded the highest percentage of 17/69 (24.63%), while the lowest percentage of 1/69 (1.4%) goes to the isolates that resist to 12 antibiotics.
Metallo Beta-lactamase (MBLs) have been phenotypically detected by Combined Disc Synergy Test (CDST), and the results showed that 4/100 (4%) of isolates were positive with MBLs while 96/100 (96%) were negative.
The genotypic detection was carried out to investigate presence of the genes blaVIM, blaGIM, blaIMP, blaSIM, blaSPM, blaKPC, blaDIM and blaNDM that are encoded by Pseudomonas aeruginosa to produce MBLs enzymes. The results revealed that 68/100 (68%) of isolates have MBLs genes. The high prevalence gene was blaNDM gene with 38/100 (38%), and the lowest prevalence were blaSPM, and blaDIM genes with 7/100 (7%). The results of the other genes prevalence were 34/100 (34%) for blaIMP gene, 26/100 (26%) for blaGIM gene, 22/100 (22%) for blaVIM gene, 12/100 (12%) for blaSIM gene, and 11/100 (11%) for blaKPC gene. (It’s worth to mention that most isolates have more than one gene).
The antibiotics susceptibility test results for all isolates of all genes showed that the highest resistant was against piperacillin and the lower resistant for most of genes was against cefepime.
The results showed the coexistence of Metallo beta-lactamase genes in most of MDR isolates. The high association of genes was 6 genes in the same isolate that revealed resistance to 8 antibiotics.
The inhibitors effect on ability of Pseudomonas aeruginosa to produce MBLs enzymes was tested using three different inhibitors Allicin, Sultamicillin tosylate and Diallyl Trisulfide. These inhibitors have been tested individually and in synchronism with antibiotics on MDR and non-MDR isolates. The results showed no role for all 3 active ingredient of garlic, and haven’t inhibitory effects on MBL enzymes.