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, Assoc.prof.dr Umut Safiye Say Coskun,
Volume 18, Issue 4 (7-2024)
Abstract
Backgrounds: Acinetobacter baumannii (A. baumannii) has emerged as the predominant etiological agent responsible for bloodstream infections among hospitalized patients. The objective of this study is to evaluate antibiotic resistance to 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 2018-2019 at the Microbiology Laboratory of
Tokat Gaziosmanpaşa University Hospital (Türkiye). The blood culture samples were incubated using the BACT-ALERT 3D system (bioMerieux, Durham, NC, USA). Microorganism identification and antibiotic susceptibility testing were performed using the VITEK 2 (bioMérieux, France) automated system.
Results: A total of 117 samples, 59.8% were taken from male and 40.2% were female. A total of 90.6% of blood culture samples were obtained from the intensive care unit and 88.9% of isolates were identified as Multidrug-resistant (MDR). The highest resistance was seen in meropenem (99.1%). The lowest resistance was observed to colistin (17.1%) and tigecycline (27.3%). The resistance against amikacin was 74.4%, while gentamicin, tobramycin, cefoxitin, cefotaxime resistance levels were within the range of 80-90%. The resistance against imipenem, amoxicillin/clavulanic acid, ampicillin/sulbactam, ceftazidime, cefepime, ciprofloxacin, levofloxacin, meropenem, and ertapenem were over the 90%.
Conclusion: The increasing number of MDR A. baumannii isolates poses a threat to all hospitalized patients. However, colistin and tigecycline are still considered preferable in the treatment of MDR A. baumannii infections. Considering the increasing MDR A. baumannii isolates, periodic analysis of epidemiological data in health centers is important to keep colistin and tigecycline resistance under control.
