Bedenić Branka, Luxner Josefa, Zarfel Gernot, Grisold Andrea, Dobrić Mirela, Đuras-Cuculić Branka, Kasalo Mislav, Bratić Vesna, Dobretzberger Verena, Barišić Ivan
Biomedical Research Center-BIMIS, University of Zagreb, School of Medicine, Department for Clinical Microbiology and Infection Control and Prevention, University Hospital Centre Zagreb, 10000 Zagreb, Croatia.
Diagnostic and Research Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, 8010 Graz, Austria.
Antibiotics (Basel). 2025 Apr 30;14(5):462. doi: 10.3390/antibiotics14050462.
BACKGROUND/OBJECTIVES: is a frequent causative agent of urinary tract and wound infections in community and hospital settings. It develops resistance to expanded-spectrum cephalosporins (ESC) due to the production of extended-spectrum β-lactamases (ESBLs) or plasmid-mediated AmpC β-lactamases (p-AmpC). Here, we report the characteristics of ESBLs and p-AmpC β-lactamases encountered among hospital and community isolates of in two hospitals and the community settings in Zagreb, Croatia.
Antibiotic susceptibility testing was performed using disk-diffusion and broth dilution methods. The double-disk-synergy test (DDST) and inhibitor-based test with clavulanic and cloxacillin were applied to screen for ESBLs and p-AmpC, respectively. PCR investigated the nature of ESBL, carbapenemases, and fluoroquinolone resistance determinants. Selected strains were subjected to molecular analysis of resistance traits by the Inter-Array CarbaResist Kit and whole-genome sequencing (WGS).
In total, 39 isolates were analyzed. Twenty-two isolates phenotypically tested positive for p-AmpC and seventeen for ESBLs. AmpC-producing organisms exhibited uniform resistance to amoxicillin-clavulanate, ESC, ciprofloxacin, and sulphamethoxazole-trimethoprim, and uniform susceptibility to carbapenems and piperacillin-tazobactam and all harbored genes. ESBL-positive isolates demonstrated resistance to amoxicillin-clavulanate, cefuroxime, cefotaxime, ceftriaxone, and ciprofloxacin but variable susceptibility to cefepime and aminoglycosides. They possessed genes that belong to cluster 1 (n = 5) or 9 (n = 12), with CTX-M-14 and CTX-M-65 as the dominant allelic variants.
The study demonstrated the presence of CTX-M ESBL and CMY-16 p-AmpC among hospital and community-acquired isolates. AmpC-producing isolates showed uniform resistance patterns, whereas ESBL-positive strains had variable degrees of susceptibility/resistance to non-β-lactam antibiotics, resulting in more diverse susceptibility patterns. The study found an accumulation of various resistance determinants among hospital and outpatient isolates, mandating improvement in detecting β-lactamases during routine laboratory work.
背景/目的：在社区和医院环境中，是引起尿路感染和伤口感染的常见病原体。由于产生超广谱β-内酰胺酶（ESBLs）或质粒介导的AmpCβ-内酰胺酶（p-AmpC），它对广谱头孢菌素（ESC）产生耐药性。在此，我们报告了在克罗地亚萨格勒布的两家医院和社区环境中，医院和社区分离株中遇到的ESBLs和p-AmpCβ-内酰胺酶的特征。
采用纸片扩散法和肉汤稀释法进行药敏试验。分别应用双纸片协同试验（DDST）和含克拉维酸和氯唑西林的抑制剂试验筛选ESBLs和p-AmpC。PCR检测ESBL、碳青霉烯酶和氟喹诺酮耐药决定簇的性质。通过Inter-Array CarbaResist试剂盒和全基因组测序（WGS）对选定菌株进行耐药性状的分子分析。
共分析了39株分离株。22株分离株p-AmpC表型检测呈阳性，17株ESBLs表型检测呈阳性。产AmpC的菌株对阿莫西林-克拉维酸、ESC、环丙沙星和磺胺甲恶唑-甲氧苄啶表现出一致的耐药性，对碳青霉烯类、哌拉西林-他唑巴坦表现出一致的敏感性，且均携带基因。ESBL阳性分离株对阿莫西林-克拉维酸、头孢呋辛、头孢噻肟、头孢曲松和环丙沙星耐药，但对头孢吡肟和氨基糖苷类药物的敏感性各异。它们拥有属于第1簇（n = 5）或第9簇（n = 12）的基因，以CTX-M-14和CTX-M-65为主要等位基因变体。
该研究证明在医院和社区获得性分离株中存在CTX-M ESBL和CMY-16 p-AmpC。产AmpC的分离株表现出一致的耐药模式，而ESBL阳性菌株对非β-内酰胺类抗生素的敏感性/耐药性程度不同，导致药敏模式更加多样化。该研究发现医院和门诊分离株中存在多种耐药决定簇的积累，这就要求在常规实验室工作中改进β-内酰胺酶的检测方法。
