Wu Qian, Shi Jing, Huang Juan, Gan Delu, Zhang Lijun, Li Pu
Department of Laboratory Medicine, The Second Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
Department of Clinical Laboratory, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
Infect Drug Resist. 2023 Sep 27;16:6395-6404. doi: 10.2147/IDR.S427836. eCollection 2023.
() is a common pathogen in bloodstream infections (BSI), and the production of extended-spectrum beta-lactamases (ESBLs) is its main mechanism of resistance. However, the impact of different ESBL genotypes of on the resistance to Cefepime (FEP) remains unclear.
A total of 2356 cases of BSI patients were collected. The experimental group included 188 ESBL-positive strains that were resistant to FEP but sensitive to ceftazidime (CAZ). Antibiotic usage and resistance rates were evaluated through antimicrobial susceptibility testing and antibiotic usage records. The ESBL genotypes were identified, and the minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) of FEP were determined.
In ESBL-positive , three ESBL genotypes were identified: 188 strains of CTX-M, 130 strains of TEM-1, and 26 strains of OXA-10. Among them, 124 strains carried both CTX-M-9 and TEM-1 genotypes, 22 strains carried two CTX-M genotypes (CTX-M-1 and CTX-M-2), 20 strains carried both CTX-M-9 and OXA-10, and 6 strains carried three genotypes (CTX-M-9, CTX-TEM-1, and OXA-10). The MIC50, MIC90, MPC50, and MPC90 of the 188 ESBL-positive were 64, 256, 128, and 528, respectively. The MIC values ranged from 32 to 256, while the MPC values ranged from 64 to 528. The MIC50, MIC90, MPC50, and MPC90 of the 40 ESBL-negative were 0.5, 1, 64, and 128, respectively; the MIC values ranged from 0.25 to 4, while the MPC values ranged from 32 to 256, respectively.
ESBL-positive induces an increase in the MIC value of FEP, leading to an increase in FEP resistance. The inoculation effect also causes a significant increase in the MPC value of FEP, especially the increase in selection index value, indicating selective enrichment and amplification of drug-resistant mutants, resulting in clinical treatment failure.
（某病原体）是血流感染（BSI）中的常见病原体，产超广谱β-内酰胺酶（ESBLs）是其主要耐药机制。然而，该病原体不同ESBL基因型对头孢吡肟（FEP）耐药性的影响尚不清楚。
共收集2356例BSI患者。实验组包括188株对FEP耐药但对头孢他啶（CAZ）敏感的ESBL阳性（该病原体）菌株。通过抗菌药物敏感性试验和抗生素使用记录评估抗生素使用情况和耐药率。鉴定ESBL基因型，测定FEP的最低抑菌浓度（MIC）和突变预防浓度（MPC）。
在ESBL阳性（该病原体）中，鉴定出三种ESBL基因型：188株CTX-M型、130株TEM-1型和26株OXA-10型。其中，124株同时携带CTX-M-9和TEM-1基因型，22株携带两种CTX-M基因型（CTX-M-1和CTX-M-2），20株同时携带CTX-M-9和OXA-10，6株携带三种基因型（CTX-M-9、CTX-TEM-1和OXA-10）。188株ESBL阳性（该病原体）的MIC50、MIC90、MPC50和MPC90分别为64、256、128和528。MIC值范围为32至256，而MPC值范围为64至528。40株ESBL阴性（该病原体）的MIC50、MIC90、MPC50和MPC90分别为0.5、1、64和128；MIC值范围为0.25至4，而MPC值范围分别为32至256。
ESBL阳性（该病原体）导致FEP的MIC值升高，从而导致FEP耐药性增加。接种效应还导致FEP的MPC值显著增加，尤其是选择指数值的增加，表明耐药突变体的选择性富集和扩增，导致临床治疗失败。
