Isolation,identification,and drug resistance testing of yak-derived microorganisms in Nagqu region
Liu Xiaojing
Qi Yan
La Zhen
Ren Kejing
Li Longjuan
An Yabin
Jin Meiluobu
Han Juanzhu
Abstract：This study aimed to analyze the bacterial carriage and drug resistance of yaks in the Nagqu region of Xizang,providing a reference for disease prevention and control in high-altitude yak farming.Bacteriological methods were used to isolate and purify bacteria from yak fecal samples collected in Nagqu.Identification was performed using microbial mass spectrometry,and drug resistance was determined by the micro-broth dilution method to preliminarily understand the characteristics of intestinal flora in yaks from high-altitude regions.The results showed that 10 strains of Escherichia coli,38 strains of Arthrobacter gandavensis,four strains of Acinetobacter calcoaceticus,one strain of Arthrobacter koreensis,two strains of Bacillus silvestris,and two strains of Enterococcus casseliflavus were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS).Drug susceptibility testing revealed that Escherichia coli exhibited high resistance to sulfonamide antibiotics,while it was sensitive to β-lactam antibiotics,aminoglycoside antibiotics,chloramphenicol antibiotics,tetracycline antibiotics,and polypeptide antibiotics,with a resistance rate of 0.Yak-derived Acinetobacter calcoaceticus showed high resistance to β-lactam antibiotics,chloramphenicol antibiotics(florfenicol),sulfonamide antibiotics,and polypeptide antibiotics(colistin).However,it was sensitive to aminoglycoside antibiotics,chloramphenicol antibiotics,and tetracycline antibiotics,with a resistance rate of 0.Arthrobacter strains exhibited low resistance rates.Gram-positive bacteria demonstrated severe antibiotic resistance,with resistance rates of 100%to penicillin,erythromycin,clindamycin,ceftiofur,cefoxitin,sulfisoxazole,vancomycin,tiamulin,tilmicosin,and linezolid.The resistance rate to amoxicillin/clavulanic acid and trimethoprim/sulfamethoxazole was 50%.These bacteria were sensitive to enrofloxacin,ofloxacin,oxacillin,tetracycline,florfenicol,and gentamicin,with a resistance rate of 0.The study indicates that yak-derived microorganisms are diverse,and the drug resistance data suggest an increased resistance of yak-derived Escherichia coli to sulfonamide antibiotics,which warrants attention.
Keywords：High-altitude regionYak-derivedBacterial drug resistanceMALDI-TOF MS
Publication Date：2025-11-15
Online Publishing Date：2025-12-16(First online date of this platform, not the publication date of the document)
Pages：7( 67-73 )