en بهداشت Health تحقیقی Original article <strong><em>&nbsp;Background</em></strong><strong> <em>and</em> <em>objectives</em>: </strong><em>Acinetobacter</em> is a genus of opportunistic pathogens that are commonly found in the environment. Given the unique ability of these bacteria to survive in the hospital, they are considered as one of the main causes of hospital-acquired infections. The emergence of multidrug-resistant <em>Acinetobacter</em> spp., particularly <em>Acinetobacter baumannii</em> has become a major health threat worldwide. In this study, we investigate antibacterial effects of probiotic isolates from goat milk on clinical isolates of <em>A. baumannii</em>.<br> <strong><em>Methods</em></strong><strong>:</strong> In this study, 100 clinical specimens were taken from patients hospitalized in six hospitals in the Golestan Province, north of Iran. Following isolation and identification of <em>A. baumannii</em> strains, antibiotic resistance patterns of the isolates were investigated using the Kirby-Bauer method according to the Clinical and Laboratory Standards Institute (CLSI-2015) guidelines. Probiotic bacteria in goat milk were isolated and identified by culture in MRS and M17 media and carbohydrate fermentation tests. Antibacterial effects of the probiotic bacteria against resistant <em>A. baumannii</em> isolates were evaluated using the agar well diffusion method.<br> <strong><em>Results</em></strong><strong>:</strong> Overall, 55% of the isolates were identified as <em>A. baumannii</em>. The highest resistance rates were observed against tobramycin (76.3%), mezlocillin (74.5%) and cefotaxime (74.5%). Resistance to levofloxacin, tetracycline, imipenem and minocycline was detected in 72.7%, 72.7%, 70.9% and 29.1% of the isolates, respectively. The most common probiotic isolates were <em>Lactobacillus plantarum</em> and <em>Lactococcus piscium</em> (30% each). The highest and lowest effects were exerted by <em>Lactococcus lactis</em> (34.54%) and <em>Lactobacillus bulgaricus</em> (3.63%), respectively.<br> <strong><em>Conclusion</em></strong>: Our results demonstrate that the prevalence of drug-resistant <em>A. baumannii</em> strains is high in the hospitals. Given the promising antimicrobial effects of the isolated probiotic bacteria, goat milk can be recommended as an adjuvant therapy or an alternative to common antibiotics for improving treatment outcome of infections caused by drug-resistant <em>A. baumannii</em>.<br> &nbsp; Acinetobacter,Goat milk,Probiotic,Nosocomial infection 31 38 http://goums.ac.ir/jorjanijournal/browse.php?a_code=A-10-541-1&slc_lang=en&sid=1 Leila Fozouni lili_kia@yahoo.com 10031947532846005307 10031947532846005307 Yes Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Maryam Yaghoobpour mary_yp@yahoo.com 10031947532846005308 10031947532846005308 No Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Ania Ahani Azari ania_783@yahoo.com 10031947532846005309 10031947532846005309 No Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran