The problem of resistance to beta-lactam antibiotics, which is caused by ESBL and AmpC β-lactamases, is getting worse globally. Infections caused by bacterial isolates harboring these enzymes are difficult to treat with carbapenems being the sole effective treatment option for such infections. The objective of this study was to determine the frequency of ESBLs and AmpC-producing Gram-negative bacilli isolated from clinical specimens and to evaluate the sensitivity of cefepime-tazobactam combination against them. This is an observational cross-sectional study carried out on 100 Gram-negative bacilli at Theodor Bilharz Research Institute Hospital during the period from February 2015 to January 2016. ESBL production was screened by using the disc diffusion test followed by confirmation by the combined disc confirmatory test, the screening for AmpC production was conducted using the cefoxitin disc test, which was subsequently confirmed by the AmpC disc test. Isolates confirmed positive for ESBL and/ or AmpC production were investigated for their susceptibility to antibiotics. Among 100 Gram-negative bacilli, 44 isolates were confirmed as ESBL producers by the combined disc confirmatory test out of 56 isolates that tested positive for ESBL production through the disc diffusion test. The presence of AmpC production was assessed using the cefoxitin disc test, 32 isolates were screened to be AmpC producers, and the AmpC disc test confirmed AmpC production in 9 isolates of them. Using the Mast® D68C set, 32 isolates were ESBL producers, 3 were AmpC producers, and 4 isolates were ESBL/AmpC co-producers. The highest sensitivity was to cefepime-tazobactam (91.48%) followed by the carbapenems. Cefepime-tazobactam showed remarkable activity against ESBL and/or AmpC-producing Gram-negative bacilli and may be considered as a therapeutic alternative to carbapenems.

中文翻译：

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头孢吡肟-他唑巴坦组合对产生广谱β-内酰胺酶和/或AmpC β-内酰胺酶的革兰氏阴性杆菌的抗菌活性

由 ESBL 和 AmpC β-内酰胺酶引起的 β-内酰胺抗生素耐药性问题在全球范围内日益严重。由含有这些酶的细菌分离株引起的感染很难治疗，碳青霉烯类是此类感染的唯一有效治疗选择。本研究的目的是确定从临床标本中分离出的 ESBL 和产 AmpC 革兰氏阴性杆菌的频率，并评估头孢吡肟-他唑巴坦组合对它们的敏感性。这是 2015 年 2 月至 2016 年 1 月期间在 Theodor Bilharz 研究所医院对 100 种革兰氏阴性杆菌进行的观察性横断面研究。使用纸片扩散试验筛选 ESBL 产量，然后通过组合纸片确认法进行确认。测试中，使用头孢西丁纸片测试对 AmpC 产生进行筛选，随后通过 AmpC 纸片测试进行了证实。对确认 ESBL 和/或 AmpC 产生呈阳性的分离株进行了抗生素敏感性调查。在 100 株革兰氏阴性杆菌中，通过纸片扩散试验检测出 ESBL 产生阳性的 56 个分离株中，有 44 个分离株通过联合纸片确认试验被确认为 ESBL 产生菌。使用头孢西丁纸片测试评估 AmpC 产生的存在，筛选出 32 个分离株为 AmpC 产生者，AmpC 纸片测试证实其中 9 个分离株产生 AmpC。使用 Mast® D68C 组，32 个分离株是 ESBL 生产者，3 个是 AmpC 生产者，4 个分离株是 ESBL/AmpC 联合生产者。对头孢吡肟-他唑巴坦的敏感性最高（91.48%），其次是碳青霉烯类。头孢吡肟-他唑巴坦对产生 ESBL 和/或 AmpC 的革兰氏阴性杆菌表现出显着的活性，可被视为碳青霉烯类的治疗替代品。