肺炎克雷伯菌对β-内酰胺类抗生素耐药性主决定因素的研究

目的了解肺炎克雷伯菌对β-内酰胺类抗生素耐药性及耐药性特点,并探究其主决定因素。方法对临床送检的痰液、咽拭子、气管分泌物等做细菌培养,根据药敏试验结果分为敏感菌株、泛耐药菌株、多重耐药菌株3种菌株。分析菌株β-内酰胺酶活性以及细胞外膜通透性的变化。结果与敏感菌株组β-内酰胺酶活性(12±6)U/mg比较,泛耐药菌株组β-内酰胺酶活性(253±36)U/mg,多重耐药菌株组β-内酰胺酶活性均明显增多,差异显著,有统计学意义(P<0.05)。而泛耐药菌株组β-内酰胺酶活性表达最高;与敏感菌株组细胞外膜通透性比较,泛耐药菌株组细胞外膜通透性、多重耐药菌株组细胞外膜通透性具有明显的阻碍作用,差异显著,有统计学意义(P<0.05)。而泛耐药菌株组细胞外膜通透性阻碍作用最强。结论β-内酰胺酶活性和细胞外膜通透性是肺炎克雷伯菌对β-内酰胺类抗生素耐药性的主决定因素。     

体外诱导多黏菌素耐药肺炎克雷伯菌的适合度代价相关研究

目的 研究体外诱导多黏菌素耐药肺炎克雷伯菌的适合度代价，并分析耐药株的分子特性。方法 采用体外诱导方法将临床分离的3株多黏菌素敏感肺炎克雷伯菌诱导成多黏菌素耐药株；微量肉汤稀释法检测体外诱导耐药前后菌株对临床常用抗菌药物的最低抑菌浓度(minimal inhibititory concentration, MIC)；采用PCR方法检测多黏菌素耐药相关基因pmrA、pmrB、mgrB、phoP和phoQ，并对阳性片段进行测序比对分析；对诱导耐药菌株及其对应敏感菌株进行生长曲线分析、生物膜形成能力检测及体外竞争和抗血清试验，分析研究多黏菌素耐药肺炎克雷伯菌的适合度代价。结果 3株诱导耐药株中均检出pmrB(T157P)突变，在诱导株FK713R和FK729R携带的mgrB基因中分别检出ISkpn14和IS5like插入序列。诱导耐药株与敏感株相比，24h生长曲线未发现明显差异；生物膜形成能力检测结果发现诱导耐药株与敏感株生物膜形成能力无明显差异；3株菌获得多黏菌素耐药后均表现出一定程度的体外竞争缺陷，竞争指数(CI值)分别为0.01、0.54和5×10-4；3株诱导耐药菌中有2株(FK713R和FK729R)与其敏感菌相比出现抗血清作用增强现象。结论 肺炎克雷伯菌获得多黏菌素耐药后会出现一定的适合度改变，不同的耐药机制可能会引起不同的适合度表现。     

医护人员暴发肺炎衣原体肺炎12例临床特征分析

目的总结肺炎衣原体(CP)肺炎暴发流行的临床特征及治疗方法。方法收集2009-01-04—2009-03-01中国医科大学附属第四医院暴发流行的12例医护人员CP肺炎咽试纸标本,应用聚合酶联反应(PCR)检测DNA,使用微量免疫荧光技术检测CP的IgG和IgM抗体,同时对肺高分辨CT结果进行分析,并评价疗效。结果本组暴发流行的CP肺炎其病原学介于CP与鹦鹉热衣原体之间的一种变异的衣原体种,且更倾向于鹦鹉热衣原体。临床表现为乏力10例,周身酸痛10例,发热6例,咳嗽、咳少量白痰2例,心悸、气短2例,皮疹1例,稀水样便1例,12例均无咯血、胸痛、呼吸困难及精神症状,肺部体征均为阴性。所有患者肺部高分辨CT均有改变,表现为多发或单发以小叶为中心阴影和腺泡状结节影3例,病变可发生在两肺各个叶段,多以外、中带分布;以小叶分布的气腔实变和磨玻璃样阴影分别为4例和1例,伴有支气管血管束增厚3例;球形影1例;结节影与实变影混合存在3例。结论医护人员CP肺炎的暴发流行具有群体发病,早期高分辨CT检查更能真实地反映病变大小、多少和分布范围。对氟喹诺酮类联合大环内酯类药物治疗有效。诊断时应与严重急性呼吸综合征、禽流感、支原体肺炎等进行鉴别。     

Characterization of carbapenem resistance mechanisms in Klebsiella pneumoniae and in vitro synergy of the colistin–meropenem combination

Abstract

In this prospective study, consecutive isolates of Klebsiella pneumoniae were tested for different mechanisms of carbapenem resistance using the modified Hodge test (MHT), Rosco Neo-Sensitabs (ROSCO). Phenylalanine arginine beta-naphthylamide assay (PABN) inhibitor-based test was done on isolates in which the mechanism of resistance was not identifiable by the ROSCO. Among 105 selected isolates, carbapenemase production was noted in 100 (95%) by MHT and ROSCO showed 97 (92·4%) inhibition with dipicolinic acid signifying the production of MBL. PCR amplification was positive in 90 (86%) isolates for bla_NDM-1 and 46 (44%) isolates for bla_OXA-48. 54 (51%) isolates were positive for bla_CTX-M and all belonged to bla_CTX-M group 1. Isolates co produced bla_OXA-48 (31/105, 30%) and bla_CTX-M (40/105, 38%) in combination with the carbapenemase (bla_NDM-1) gene. Five colistin-resistant isolates were positive for bla_OXA-48. Eight isolates did not show inhibition with any of the inhibitor containing disks and found to be positive for bla_OXA-48. Isolates were tested for colistin-meropenem synergy and detection rate was higher by the checkerboard (48%) than E-test method (35%). Our study necessitates continuous surveillance to recognize the predominant machinery of resistance in a particular geographical region to formulate effective control measures.     

Antimicrobial Resistance in Gram-Negative Hospital Isolates: Results of the Turkish HITIT-2 Surveillance Study of 2007

Abstract

Resistance rates to amikacin, ciprofloxacin, ceftazidime, cefepime, imipenem, cefoperazone/sulbactam and piperacillin/tazobactam in Escherichia coli (n= 438)Klebsiella pneumoniae (n= 444)Pseudomonas aeruginosa (n= 210) and Acinetobacterbaumanni (n=200) were determined with e-test in a multicenter surveillance study (HITIT-2) in 2007. ESBL production in Escherichia coli and K. pneumoniae was investigated following the CLSI guidelines. Overall 42.0% of E.coli and 41.4% of K. pneumoniae were ESBL producers. In E. coli, resistance to imipenem was not observed, resistance to ciprofloxacin and amikacin was 58.0% and 5.5% respectively. In K. pneumoniae resistance to imipenem, ciprofloxacin and amikacin was 3.1%, 17.8% 12.4% respectively. In P. aeruginosa the lowest rate of resistance was observed with piperacillin/tazobactam (18.1%). A. baumanni isolates were highly resistant to all the antimicrobial agents, the lowest level of resistance was observed against cefoperazone/sulbactam (52.0%) followed by imipenem (55.5%). This study showed that resistance rates to antimicrobials are high in nosocomial isolates and show variations among the centers.     

Occurrence of Extended-Spectrum Betalactamases (ESBL) in Dutch Hospitals

Summary The prevalence of ESBL was determined among isolates of Escherichia coli (n = 571) and Klebsiella spp. (n = 196) collected during a 1-week study period in 8 university and 3 large regional laboratories all over the Netherlands. 18 isolates were positive for at least one of the screening tests used, i.e., VITEK-ESBL, E-test ESBL and MIC ratio of ceftazidime/ceftazidime-clavulanic acid, cefotaxime/cefotaxime-clavulanic acid. In 5 of these 18 putative ESBLs no betalactamase production was detectable. A TEM type was found in three E. coli and two Klebsiella spp. An SHV type was present in five Klebsiella spp. In one E. coli and one Klebsiella pneumoniae both enzymes were present. In one Klebsiella oxytoca neither of the two enzymes was present. Using PCR for both ESBL TEM and ESBL SHV, an SHV ESBL was found in one E. coli and four Klebsiella isolates. The mutations at position 238 and 240 were already described. In one E. coli isolate a TEM ESBL was found with three mutations, at position 21, 164 and 265. These mutations were already described in other ESBLs but not in this combination suggesting a new TEM ESBL. The overall prevalence of ESBL producing E. coli and Klebsiella spp. was less than 1% (6 out of 767). Received: December 14, 1998 · Accepted: September 19, 1999     

Streptococcus pneumoniae Peritonitis Postpartum

Summary A peritonitis cause by an ascending infection is a rare complication postpartum. A 37-year-old women presented with a secondary peritonitis due to Streptococcus pneumoniae. The patient had given birth to a healthy boy 4 weeks before and showed no symptoms of a bronchitis on admission. A operation was performed after the patient developed an acute abdomen, showing a diffuse peritonitis. High vaginal swabs and blood cultures taken on admission were positive for S. pneumoniae as well as the specimen taken during the operation. Thus we concluded that this was a case of an ascending infection. After antibiotic therapy with penicillin the patient could be discharged 8 days after the operation. Received: July 6, 1999 · Accepted: January 5, 2000