改良头孢西丁平板试验检测大肠埃希菌和肺炎克雷伯菌质粒介导的AmpC酶

目的依据EDTA可渗透菌细胞内并促进β-内酰胺酶释放至外环境的原理,建立并评价检测大肠埃希菌和肺炎克雷伯菌质粒介导的AmpC酶的改良头孢西丁平板试验（MCAM）。方法于含有2、4、6、8μg/ml的头孢西丁平板上接种过夜培养的大肠埃希菌ATCC25922,然后用直径5mm的打孔器在琼脂表面均匀间隔打孔,于孔中分别加入0.5mol/LEDTA0、3、5、7、10μl（使孔中约含EDTA分别为0、450、750、1000、1500μg）,各孔加待检菌悬液（〉1011CFU/ml）25μl,35℃过夜培养。以孔周有细菌生长环为AmpCs阳性。以阴沟肠杆菌029M和大肠埃希菌ATCC25922作质控,用MCAM和酶粗提物三维试验（TDEM）同时检测临床分离的头孢西丁不敏感大肠埃希菌（14株）和肺炎克雷伯菌（13株）的AmpC酶,对两种方法进行比较。结果MCAM试验应用6μg/ml头孢西丁平板和750μgEDTA进行检测,其结果与TDEM试验完全一致。结论该方法操作简便、结果易于判读,在一块平板上可同时进行多株菌的检测,适于各级临床微生物实验室应用。     

Plazomicin: an intravenous aminoglycoside antibacterial for the treatment of complicated urinary tract infections

ABSTRACT

Introduction

Antimicrobial resistance continues to be a major public health concern due to the emergence and spread of multi-drug resistant (MDR) organisms, including extended spectrum ß-lactamase (ESBL) and carbapenemase producing Enterobacterales. Plazomicin is a novel aminoglycoside that demonstrates activity against MDR gram-negatives, including those producing ESBLs and most carbapenemases, and retains activity against aminoglycoside modifying enzymes as a result of structural modifications. The information discussed is meant to assist in identifying plazomicin’s place in therapy and to expand the clinician’s armamentarium.     

ICU患者发生产ESBLs革兰阴性杆菌 感染的危险因素分析及预测模型的建立

[摘要]　目的　探讨ICU患者发生产超广谱β-内酰胺酶（extended spectrum beta-lactamases, ESBLs）革兰阴性杆菌感染的危险因素,并构建相关预测模型。方法　选取2017年5月—2021年4月我院ICU发生大肠埃希菌或肺炎克雷伯菌感染的189例患者作为研究对象,收集患者的临床资料,使用单因素分析、LASSO回归和多因素Logistic回归分析ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的危险因素,并据此建立列线图预测模型。结果　急性生理与慢性健康评分≥16分、留置尿管时长≥7 d、抑酸剂使用时长≥3 d、第三代头孢菌素使用时长≥3 d、抗菌药物联用时长≥3 d和ICU住院时间≥15 d是ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的危险因素（P均＜0.05）。依此建立预测ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的列线图风险模型,模型验证结果显示C-index为0.795,校正曲线趋近于理想曲线,AUC为0.807（95%CI：0.775～0.839）,在2%～81%预测范围内,列线图净获益。结论　ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的危险因素包括APACHEⅡ评分≥16分、留置尿管时长≥7 d、抑酸剂使用时长≥3 d、第三代头孢菌素使用时长≥3 d、抗菌药物联用时长≥3 d和ICU住院时间≥15 d,据此构建的列线图模型能有效预测ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的风险概率,具有一定的临床价值。     

Ceftibuten-induced filamentation of extended spectrum beta lactamase (ESBL)-producing uropathogenic Escherichia coli alters host cell responses during an in vitro infection

Inadequate and delayed antibiotic treatment of extended spectrum beta-lactamase (ESBL)-producing isolates have been associated with increased mortality of affected patients. The purpose of this study was to compare the host response of human renal epithelial cells and polymorphonuclear leucocyte (PMN) cells when infected by ESBL-producing uropathogenic Escherichia coli (UPEC) isolates in the presence or absence of ineffective antibiotics.The renal epithelial cell line A498 and PMN cells were stimulated with ESBL-producing UPEC isolates in the presence or absence of three different antibiotics (trimetoprim, ceftibuten and ciprofloxacin). Host cell responses were evaluated as release of cytokines (IL-6, IL-8), reactive oxygen species (ROS), ATP and endotoxins. Bacterial morphology and PMN phagocytosis were evaluated by microscopy.In the presence of ceftibuten, 2 out of 3 examined ESBL-isolates changed their morphology into a filamentous form. The presence of ceftibuten enhanced IL-6, IL-8 and ROS-production from host cells, but only from cells stimulated by the filamentous isolates. The bacterial supernatant and not the filamentous bacteria per se was responsible for the increased release of IL-6, IL-8 and ROS. Increased endotoxin and ATP levels were found in the bacterial supernatants from filamentous isolates. Apyrase decreased IL-6 secretion from A498 cells and polymyxin B abolished the increased ROS-production from PMN cells. PMN were able to inhibit the bacterial growth of some ESBL-isolates in the presence of ceftibuten.In conclusion, antibiotic-induced filamentation of ESBL-producing UPEC isolates and the associated release of ATP and endotoxins can alter the host cell response in the urinary tract.