Arvin Shajeie, Mehrnaz Rad, Mahdi Askari, Kamran Sharifi, Gholamreza Hashemi Tabar,
Volume 17, Issue 5 (9-2023)
Abstract
Background: Colistin is the most significant last-line antibiotic for the treatment of multidrug-resistant infections caused by Gram-negative bacteria, especially the Enterobacteriaceae family. The emergence and rapid spread of the plasmid-mediated resistance gene, mcr-1 (mobilized colistin resistance), in some isolates of Escherichia coli in recent years provoked public health concerns since it has been shown that mcr-1 with other resistance genes, such as ESBLs (extended-spectrum beta-lactamases) and carbapenemases, could be carried on a single plasmid concurrently. The excessive consumption of colistin, particularly in the livestock industry, and the transmission of these resistant bacteria from livestock to humans may potentially increase the risk of the spread of resistance in humans. Therefore, this study aimed to detect the prevalence of mcr and carbapenem resistance genes among neonatal calves in Mashhad, Razavi Khorasan Province, Iran.
Methods: In the current study, 200 fecal samples from healthy and diarrheic neonatal calves (≤35 days old) were collected in Mashhad (190 E. coli strains were isolated). Antibiotic susceptibility to ceftazidime, cefepime, cefixime, meropenem, colistin, and ciprofloxacin was examined. The double-disk diffusion method (ceftazidime + ceftazidime/clavulanic acid) was performed on Mueller-Hinton agar (MHA) media to phenotypically distinguish the ESBL producers. Afterward, the Multiplex polymerase chain reaction (PCR) method was used to detect colistin resistance genes (mcr-1, mcr-2, mcr-3, mcr-4, and mcr5), NDM-1 (New Delhi metallo-beta-lactamase 1), and OXA-48 as carbapenemases.
Results: The results of the resistance rate to antibiotics were cefepime, ceftazidime, cefixime, meropenem, and colistin. Based on the findings, 33.7% were phenotypically ESBL producers, 4.21% harbored mcr-1, and no NDM-1 or OXA-48 was detected. Among the mcr-1-positive isolates, 5 strains showed the ESBL phenotype.
Conclusion: The results highlight the need for continued monitoring of antibiotic resistance in livestock and the potential for transmission to humans. The findings also underscore the importance of responsible antibiotic use in both human and animal health to mitigate the spread of antibiotic resistance.
Zaid Faris Hasan , Umut Safiye Şay Coşkun,
Volume 18, Issue 4 (7-2024)
Abstract
Background: Acinetobacter baumannii (A. baumannii) has emerged as the predominant etiological agent responsible for bloodstream infections among hospitalized patients. The objective of this study was to evaluate antibiotic resistance in A. baumannii isolates identified from blood cultures.
Methods: A retrospective cohort evaluation was conducted on 117 A. baumannii isolates obtained from blood cultures collected between 2018 and 2019 at the Microbiology Laboratory of Tokat Gaziosmanpaşa University Hospital (Türkiye). The blood culture samples were incubated using the BACT-ALERT 3D system (bioMérieux, Durham, NC, USA). Microorganism identification and antibiotic susceptibility testing were performed using the VITEK 2 (bioMérieux, France) automated system.
Results: Of the 117 samples, 59.8% were obtained from males and 40.2% from females. A total of 90.6% of blood culture samples were collected from the intensive care unit, and 88.9% of isolates were identified as multidrug-resistant (MDR). The highest resistance was observed against meropenem (99.1%), while the lowest resistance was noted for colistin (17.1%) and tigecycline (27.3%). Resistance to amikacin was 74.4%, while resistance levels to gentamicin, tobramycin, cefoxitin, and cefotaxime were within the range of 80–90%. Resistance to imipenem, amoxicillin/clavulanic acid, ampicillin/sulbactam, ceftazidime, cefepime, ciprofloxacin, levofloxacin, meropenem, and ertapenem exceeded 90%.
Conclusion: The increasing number of MDR A. baumannii isolates poses a significant threat to all hospitalized patients. However, colistin and tigecycline remain preferable options for the treatment of MDR A. baumannii infections. Considering the increasing prevalence of MDR A. baumannii isolates, periodic analysis of epidemiological data in healthcare centers is important for managing resistance to colistin and tigecycline.
