Nasilele Situmbeko J, Shawa Misheck, Kamboyi Harvey K, Phiri Bruno S J, Chambaro Herman, Lundu Tapiwa, Nundwe Mike, Lungu Angela, Moonga Ladslav, Kajihara Masahiro, Sawa Hirofumi, Suzuki Yasuhiko, Higashi Hideaki, Siame Amon, Mudenda Ntombi B, Hang'ombe Mudenda B, Muzandu Kaampwe
Biomedical Sciences Department, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia.
Hokudai Center for Zoonosis Control in Zambia, University of Zambia, Lusaka 10101, Zambia.
JAC Antimicrob Resist. 2025 Jul 22;7(4):dlaf125. doi: 10.1093/jacamr/dlaf125. eCollection 2025 Aug.
The inappropriate use of antimicrobials in poultry farming is associated with the emergence of antimicrobial-resistant Enterobacterales. This cross-sectional study aimed to identify various cefotaxime-resistant and β-lactamase-producing Enterobacterales and characterize their antimicrobial resistance profiles.
Pooled cloacal and meat samples collected from market-ready broiler chickens in Kitwe and Ndola districts of Zambia were screened for cefotaxime-resistant Enterobacterales. The samples were inoculated on MacConkey agar supplemented with 1 mg/L cefotaxime. The cefotaxime-resistant isolates were further subjected to antimicrobial susceptibility tests. Further, the isolated cefotaxime-resistant Enterobacterales were analysed for , , and genes using PCR and Sanger sequencing.
From a total of 114 pooled samples, 81 (71.1%) cefotaxime-resistant Gram-negative strains were isolated. These were dominated by (77.8%) followed by (6.2%), spp. (6.2%), (4.9%), (2.5%), spp. (1.2%) and (1.2%). Furthermore, 64.2% of the 81 isolates exhibited multidrug resistance with high resistance (>64%) to ampicillin, co-trimoxazole and tetracycline. The results also showed that 66.7% of the isolates harboured at least one of the four tested genes ( , , and ), with the commonest being (58%) and (45.7%).
The study revealed a high prevalence of cefotaxime-resistant Enterobacterales and multidrug resistance involving medically important antibiotics. Four genes ( , , and ) were identified. Our results highlight the need to strengthen antimicrobial stewardship programmes and optimize antimicrobial use in poultry farming.
家禽养殖中抗菌药物的不当使用与产超广谱β-内酰胺酶肠杆菌科细菌的出现有关。本横断面研究旨在鉴定各种对头孢噻肟耐药且产β-内酰胺酶的肠杆菌科细菌，并描述其抗菌药物耐药谱。
从赞比亚基特韦和恩多拉地区即将上市的肉鸡中收集泄殖腔和肉的混合样本，筛选对头孢噻肟耐药的肠杆菌科细菌。将样本接种在补充有1mg/L头孢噻肟的麦康凯琼脂上。对头孢噻肟耐药菌株进一步进行药敏试验。此外，使用聚合酶链反应（PCR）和桑格测序法分析分离出的对头孢噻肟耐药的肠杆菌科细菌的blaCTX-M、blaTEM、blaSHV和blaOXA基因。
在总共114份混合样本中，分离出81株（71.1%）对头孢噻肟耐药的革兰氏阴性菌株。其中以大肠埃希菌（77.8%）为主，其次是肺炎克雷伯菌（6.2%）、阴沟肠杆菌属（6.2%）、产气肠杆菌（4.9%）、弗劳地枸橼酸杆菌（2.5%）、粘质沙雷菌属（1.2%）和摩根氏菌属（1.2%）。此外，81株分离株中有64.2%表现出多重耐药性，对氨苄西林、复方新诺明和四环素的耐药率较高（>64%）。结果还显示，66.7%的分离株携带四个检测的bla基因（blaCTX-M、blaTEM、blaSHV和blaOXA）中的至少一个，最常见的是blaCTX-M（58%）和blaTEM（45.7%）。
该研究揭示了对头孢噻肟耐药的肠杆菌科细菌的高流行率以及涉及重要医学抗生素的多重耐药性。鉴定出了四个bla基因（blaCTX-M、blaTEM、blaSHV和blaOXA）。我们的结果强调了加强抗菌药物管理计划和优化家禽养殖中抗菌药物使用的必要性。
