Investigating the prevalence of colistin resistance and the presence of mcr-۱, mcr-۲, mcr-۳ and pmra, pmrb genes in gram-negative bacteria isolated from respiratory samples of patients with covid-۱۹.

BACKGROUND AND OBJECTIVESVentilator-related pneumonia is one of the most important causes of death in intensive care units (Lahorepur, ۲۰۱۹). Patients with covid-۱۹ are at increased risk of secondary bacterial infections due to the use of invasive catheters and impaired host immunity. So that the death of cases that encountered bacterial co-infection with covid-۱۹ has been reported recently (Ponset-Megmont ۱ et al., ۲۰۲۰; Ferguson ۲ et al., ۲۰۲۰). Therefore, in this study, we investigated the prevalence of colistin resistance in gram-negative bacteria isolated from the trachea of patients with Covid-۱۹ using phenotypic and genotypic methods.MATERIALS AND METHODS۹۶ isolates of Gram-negative bacteria were isolated from the trachea samples of patients with Covid-۱۹ in Al-Zahra Hospital, Isfahan. Microbial sensitivity test for twelve different antibiotics was investigated by standard Kirby Baer method. Determining the minimum inhibitory concentration of colistin was checked by broth microdilution method and the presence of mcr-۱, mcr-۲, mcr-۳, pmra and pmrb genes was identified by PCR method and if it was positive, sequencing was done.RESULTS AND DISCUSSIONIn this study, the most isolates (۳۷.۵%) were isolated from the ICU department and the least isolates (۱۳.۹%) from the surgical department. The isolates included ۷۳% Acinetobacter baumannii, ۱۶.۲% Klebsiella pneumoniae, ۶.۷% Pseudomonas aeruginosa and ۴.۱% Escherichia coli. The highest resistance to ampicillin (۹۴.۶%) and the lowest resistance to gentamicin and ceftazidime with ۷۴.۳% frequency were observed. Based on the MIC results, the average MIC concentration of the antibiotic Cleistin was ۱۳.۷ μg/ml. The lowest level of resistance was observed at concentrations of ۳۲, ۶۴, and ۱۲۸ μg/ml (۱.۴% of isolates) and the highest level of resistance to the antibiotic colistin was observed at concentration of ۱ μg/ml (۲۳% of isolates). ۱۸.۹% (۱۴.۷۴) isolates had pmrAB resistance gene and no colistin resistance genes (mcr-۱, mcr-۲ and mcr-۳) were found in any of the isolates.CONCLUSIONIn this study, the level of resistance to colistin in gram-negative bacteria isolated from patients with covid-۱۹ was relatively high, and because colistin is the last treatment option for gram-negative bacteria, resistance to colistin is a serious problem all over the world. Therefore, it is very important to obtain information about colistin resistance and continuous monitoring to determine the frequency of different genes, because these data can be used to create appropriate guidelines regarding the special use of this antibiotic to prevent resistance to colistin.

کلیدواژه ها:

Covid-۱۹ ، Gram-negative bacteria ، Resistance to colistin ، mcr-۱ ، mcr-۲ ، mcr-۳ ، pmra and pmrb.