Table 1_Identification of antimicrobial resistant bacteria isolated from Hyalomma excavatum and Hyalomma dromedarii infesting camels in Aljouf region, Saudi Arabia.docx

Ticks and tick-borne pathogens are expanding their geographic ranges to novel suitable habitats. Together with the World Health Organization (WHO) and the United Nations (UN), Saudi Arabia’s government has joined efforts to prevent the development of tick-associated pathogens. Here, we investigated the prevalence and diversity of antimicrobial-resistant (AMR) bacteria in ticks parasitizing camels in Al-Jouf province. A total of 60 ticks were sampled and identified as Hyalomma excavatum (n = 41) and Hyalomma dromedarii (n = 19), infesting 11 camels. Altogether 70 bacterial isolates were isolated and subjected to Gram staining, followed by identification using the Vitek 2 compact system. Bacterial isolates consisted of 23 different bacterial species. 68.6% (n = 48) of the total isolates were identified as Gram-positive bacteria, comprising 14 different species, while 31.4% (n = 22) of the total isolates were Gram-negative bacteria, comprising 9 different species. Each collected tick was found positive for at least one bacterial species, however, 9 out of the 70 ticks were found to carry 2 or 3 bacterial species. Antimicrobial susceptibility testings showed that the isolated bacteria exhibited resistance to several clinical antimicrobial agents. The antimicrobial susceptibility profile of Gram-positive bacteria showed that 100% (n = 30) were resistant to benzylpenicillin; 93.3% (n = 28) were resistant to and oxacillin; 56.7% (n = 17) were resistant to clindamycin; 53.3% (n = 16) were resistant to vancomycin; 43.3% (n = 13) were resistant to rifampicin; 40% (n = 12) were resistant to erythromycin and trimethoprim/sulfamethoxazole; 30% (n = 9) were resistant to teicoplanin; 3.3% (n = 1) was resistant to tetracycline. All Gram-positive bacteria were 100% susceptible to linezolid, gentamicin, tobramycin, levofloxacin, moxifloxacin, and tigecycline. Susceptibility testing for Gram-negative bacteria revealed, 75% (n = 12) were resistant to cefoxitin, whereas 68.75% (n = 11) were resistant to ampicillin. 62.5% (n = 10) of the Gram-negative bacteria were resistant to ceftazidime. In addition, 50% (n = 8) were resistant to cephalothin, ceftriaxone, and trimethoprim/sulfamethoxazole; 43.75% (n = 7) were resistant to cefepime; 31.25% (n = 5) were resistant to amoxicillin/clavulanic acid; 6.25% (n = 1) was resistant to nitrofurantoin. However, all Gram-negative bacteria were susceptible to other antimicrobials including piperacillin/ tazobactam, imipenem, meropenem, amikacin, gentamicin, ciprofloxacin and tigecycline. The current study sheds light on the AMR burden in ticks infesting camels in Al-Jouf province.

蜱虫及其携带的蜱传病原体正向着全新适宜栖息地扩张地理分布范围。与世界卫生组织（World Health Organization, WHO）及联合国（United Nations, UN）协同，沙特阿拉伯政府已加入防控蜱相关病原体滋生的行动行列。本研究针对焦夫省（Al-Jouf province）寄生在骆驼体内的蜱虫所携带的抗菌药物耐药性（antimicrobial-resistant, AMR）细菌的流行率与多样性展开调查。共计采集60只蜱虫，经鉴定为挖掘璃眼蜱（Hyalomma excavatum，n=41）与骆驼璃眼蜱（Hyalomma dromedarii，n=19），它们寄生于11头骆驼。总计分离得到70株细菌分离株，先进行革兰氏染色，随后采用Vitek 2 compact系统完成菌种鉴定。分离得到的细菌涵盖23个不同菌种：其中68.6%（n=48）为革兰氏阳性菌，包含14个不同物种；剩余31.4%（n=22）为革兰氏阴性菌，包含9个不同物种。每一枚采集到的蜱虫均检出至少一种细菌，然而70株分离株中有9株携带2或3种细菌。抗菌药物敏感性试验结果显示，分离菌株对多种临床常用抗菌药物呈现耐药性。革兰氏阳性菌的药敏谱特征为：100%（n=30）对苄青霉素（benzylpenicillin）耐药；93.3%（n=28）对苯唑西林（oxacillin）耐药；56.7%（n=17）对克林霉素（clindamycin）耐药；53.3%（n=16）对万古霉素（vancomycin）耐药；43.3%（n=13）对利福平（rifampicin）耐药；40%（n=12）对红霉素（erythromycin）与甲氧苄啶/磺胺甲噁唑（trimethoprim/sulfamethoxazole）耐药；30%（n=9）对替考拉宁（teicoplanin）耐药；仅3.3%（n=1）对四环素（tetracycline）耐药。所有革兰氏阳性菌均对利奈唑胺（linezolid）、庆大霉素（gentamicin）、妥布霉素（tobramycin）、左氧氟沙星（levofloxacin）、莫西沙星（moxifloxacin）以及替加环素（tigecycline）100%敏感。革兰氏阴性菌的药敏试验结果显示：75%（n=12）对头孢西丁（cefoxitin）耐药；68.75%（n=11）对氨苄西林（ampicillin）耐药；62.5%（n=10）对头孢他啶（ceftazidime）耐药；另有50%（n=8）对头孢噻吩（cephalothin）、头孢曲松（ceftriaxone）以及甲氧苄啶/磺胺甲噁唑耐药；43.75%（n=7）对头孢吡肟（cefepime）耐药；31.25%（n=5）对阿莫西林/克拉维酸（amoxicillin/clavulanic acid）耐药；仅6.25%（n=1）对呋喃妥因（nitrofurantoin）耐药。不过所有革兰氏阴性菌均对哌拉西林/他唑巴坦（piperacillin/tazobactam）、亚胺培南（imipenem）、美罗培南（meropenem）、阿米卡星（amikacin）、庆大霉素、环丙沙星（ciprofloxacin）以及替加环素等其余抗菌药物保持敏感。本研究阐明了焦夫省寄生骆驼的蜱虫所携带的抗菌药物耐药性细菌的流行负担现状。