فهرست مطالب arvin shajeie

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.

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.

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.

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.

Q fever is a zoonotic disease caused by an obligate gram-negative intracellular pathogen called Coxiella burnetii. The aim of this study was to determine the seroprevalence of anti-C. burnetii antibodies in bulk tank milk (BTM) samples of dairy cattle in west and northwest of Iran.

Overall, 71 BTM samples (covering nearly 700 dairy cattle) were collected in autumn 2013. A commercial Q fever antibody ELISA Test Kit (Liebefeld-Bern, Switzerland) was used to identify the presence of antibodies against inactivated phase 1 and phase 2 C. burnetii antigens.

The results of ELISA test showed that 17 BTM samples (23.9%) were positive for the presence of anti-C. burnetii antibodies.

This study is the first to evaluate presence of anti-C. burnetii antibodies in BTM samples from dairy cattle herds in west and northwest of Iran. The high prevalence of this pathogen highlights the need for pasteurization of raw milk and raising awareness in consumers of dairy products in these regions.