Detection of expanded-spectrum β-lactamases in Gram-negative bacteria in the 21st century

Emerging β-lactamase-producing-bacteria (ESBL, AmpC and carbapenemases) have become a serious problem in our community due to their startling spread worldwide and their ability to cause infections which are difficult to treat. Diagnosis of these β-lactamases is of clinical and epidemiological interest. Over the past 10 years, several methods have been developed aiming to rapidly detect these emerging enzymes, thus preventing their rapid spread. In this review, we describe the range of screening and detection methods (phenotypic, molecular and other) for detecting these β-lactamases but also whole genome sequencing as a tool for detecting the genes encoding these enzymes.     

Combination Therapy in Systemic Mycosis

Summary

One hundred eighty-four sputum specimens from the same number of patients with lower respiratory tract infections were examined to determine the bacterial count and the relationship between the microorganisms isolated and the presumptive pathology. The sputa were subdivided into three groups; “high probability”, “low probability”, and “contaminated sputa”, following the criteria of the microscopic readings: sputum with more than 25 white cells and low numbers of squamous epithelial cells represents true lower respiratory tract infections (high probability); those with fewer than 25 white cells represent non-bacterial infections or non-infected sputa (low probability) while sputa with more than 25 squamous cells per field represent contaminated specimens (contaminated sputa).

Statistical analysis was carried out to correlate these data. Haemophilus influenzae, Haemophilus parainfluenzae, Streptococcus pneumoniae, and Streptococcus pyogenes showed significant differences in the three groups considered.     

头孢哌酮/舒巴坦对ICU常见革兰阴性杆菌抗菌活性的研究

目的 了解头孢哌酮/舒巴坦对临床常见革兰阴性杆菌的抗菌活件,比较不同浓度的头孢哌酮/舒巴坦纸片药敏试验结果的差异.方法 分离自浙江大学医学院附属第二医院、浙江省人民医院、杭州市第三人民医院和杭州市中医院的临床常见381株革兰阴性杆菌用头孢哌酮/舒巴坦含量75/75(150)和头孢哌酮/舒巴坦含量75/30(105)的药敏纸片进行K-B法药敏试验,同时用标准的琼脂稀释法检测头孢哌酮/舒巴坦的最低抑菌浓度(MIC),并采用WHONET 5.4软什和SPSS统计软件对实验结果进行分析.结果 头孢哌酮/舒巴坦105浓度和150浓度纸片法检测大肠埃希菌、肺炎克雷伯菌、铜绿假单胞菌和鲍曼不动杆菌,两种浓度纸片的符合率分别为:26.3%,79.2%,83.7%和33%,用SPSS 10.0统计k-related samples检验,P＜0.05;105浓度纸片法和琼脂稀释法针对以上4种菌的比对符合率分别为77.8%,89.6%,70.9%和77%;150浓度纸片法和琼脂稀释法的比对符合率分别为:27.3%,79.2%,61.6%和30%,两种浓度纸片法和稀释法的误差率比较,150纸片的假敏感和假中介要高于105纸片.结论 105浓度纸片法的结果更接近于作为金标准的稀释法,而目前临床药敏实验使用的150浓度的纸片法提高了细菌的敏感性.     

Pseudomonas aeruginosa treatment and transmission reduction

Infections caused by Pseudomonas aeruginosa can be difficult to treat and require a coordinated approach for their management. This involves quickly controlling the source of infection, establishing a correct etiologic diagnosis and administering appropriate empiric antimicrobial therapy. Once antimicrobial therapy has been initiated and susceptibilities are available, therapy should be tailored with optimized antibiotic doses for an appropriate duration in order to sufficiently treat the infection and minimize resistance emergence.     

A simple,robust and rapid approach to detect carbapenemases in Gram-negative isolates by MALDI-TOF mass spectrometry: validation with triple quadripole tandem mass spectrometry,microarray and PCR

Carbapenemases should be accurately and rapidly detected, given their possible epidemiological spread and their impact on treatment options. Here, we developed a simple, easy and rapid matrix-assisted laser desorption ionization-time of flight (MALDI-TOF)-based assay to detect carbapenemases and compared this innovative test with four other diagnostic approaches on 47 clinical isolates. Tandem mass spectrometry (MS-MS) was also used to determine accurately the amount of antibiotic present in the supernatant after 1 h of incubation and both MALDI-TOF and MS-MS approaches exhibited a 100% sensitivity and a 100% specificity. By comparison, molecular genetic techniques (Check-MDR Carba PCR and Check-MDR CT103 microarray) showed a 90.5% sensitivity and a 100% specificity, as two strains of Aeromonas were not detected because their chromosomal carbapenemase is not targeted by probes used in both kits. Altogether, this innovative MALDI-TOF-based approach that uses a stable 10-μg disk of ertapenem was highly efficient in detecting carbapenemase, with a sensitivity higher than that of PCR and microarray.     

Genetics of Fungi Pathogenic for Man

Abstract

Great strides have been made in research on fungi pathogenic to man and animal during the last three decades, but little progress has been made in the genetics of these microorganisms. The principal reason for such a delay in genetic research is that mechanisms for genetic recombination were not known to exist in most of the pathogens.¹ It was not until the early part of the last decade that the parasexual cycle in Aspergillus fumigatus² and heterothallism in several ringworm fungi were discovered.^3-8 The reports of heterothallism in dermatophytes stimulated medical mycologists to search for the perfect state in systemic pathogens. Within the last 5 years, heterothallism has been discovered in Blastomyces dermatitidis, Histo-plasma capsulatum, and Geotrichum candidum.^9-11 Although for the last 10 years steady progress has been made employing these fungi as genetic tools, our knowledge of the genetics of human pathogenic fungi is fragmentary compared with what is known about the saprophytes and plant pathogens. This review is restricted to the results of recent genetic studies on true fungi pathogenic to man and animals. Although pathogenic fungi, by broad definition, might include those producing poisonous effects upon ingestion and those which cause disease only rarely and under special circumstances, this review is devoted only to those fungi generally recognized as pathogens for man. An understanding of the basic principles of mycology and genetics is assumed.     

CHARACTERIZATION AND ANTI-MICROBIAL SUSCEPTIBILITY OF GRAM-NEGATIVE BACTERIA ISOLATED FROM BLOODSTREAM INFECTIONS OF CANCER PATIENTS ON CHEMOTHERAPY IN PAKISTAN

Purpose: Bloodstream infection remains a major cause of morbidity and mortality in patients undergoing treatment for cancer. Severe infections due to Gram-negative bacilli & staphylococci are common in cancer patients. Altered gut flora because of frequent antibiotic administration and damage of epithelial surfaces contribute to the development of infection. To access the use of new potent antibiotics against bloodstream infection in cancer patients and to determine the cross resistance of Gram-negative bacterial strains. Materials and Methods: We studied the bacterial spectrum & antimicrobial susceptibility pattern of cephalosporins, fluoroquinolones, carbapenems and aminoglycosides against Gram-negative bacterial strains in cancer patients. The susceptibility was determined by broth dilution method according to National Committee for Clinical Laboratory Standards (NCCLS) now called Clinical Laboratory Standards Institute (CLSI) during study period (July 2006 to Jan 2007). Results: A total of 60 Gram-negative bacterial blood cultures were examined. Among these, Pseudomonas aeruginosa was the most common (38%). The Minimum Inhibitory Concentration at which 50% (MIC₅₀) and 90% (MIC₉₀) of Enterobacteriaceae and P. aeruginosa inhibited were found. Resistance in P.aeruginosa against cefepime, meropenem, ciprofloxacin, ceftriaxone, tobramycin, cefoperazone and imipenem was 60%, 13%, 80%, 67%, 40%, 90% and 10% respectively while for Enterobacteriaceae 80%, 20%, 88%, 72%, 20%, 90% and four per cent resistance was observed. Meropenem was found to be the most effective antimicrobial against Gram-negative bacteria. Conclusion: High resistance observed in this study warrants the needs of surveillance of resistant pattern of antimicrobial agents. Due to increased level of drug resistance, carbapenem would be a prudent choice in high- risk cases.     

单管多用快速鉴定培养基在临床微生物实验教学中的应用

目的:简化革兰阴性菌鉴定程序,缩短鉴定时间,便于学生掌握实验技能,提高教学质量。方法:将4株实验菌株分别接种于自己研制的尿素苯丙氨酸单管多用快速鉴定培养基与购买商品化的单管尿素、苯丙氨酸鉴定培养基做对比实验。结果:该课题所选择的两项试验,应用自制尿素苯丙氨酸单管多用快速鉴定培养基只需接种一管鉴定培养基内,35℃,培养3h,即可得到尿素苯丙氨酸试验结果;接种于购买商品化的单管尿素、苯丙氨酸鉴定培养基需接种两支不同鉴定培养基内35℃,培养24h,才能得到尿素苯丙氨酸试验结果。结论:自制尿素苯丙氨酸单管多用快速鉴定培养基,经两组鉴定培养基的对比实验,证明该培养基设计合理,4株实验菌鉴定准确率为100%,操作简单,培养鉴定时间明显缩短,结果易于判定,因此自制的尿素苯丙氨酸单管多用快速鉴定培养基非常适用于临床微生物实验教学。     

我院2005～2006年医院感染病原菌分布及其耐药性研究

目的:了解我院近2年医院感染病原菌的分布及其耐药性。方法:采用回顾性调查方法,对4653株病原菌进行统计分析。结果:真菌709株,占15.2%;革兰阳性(G+)球菌1078株,占23.2%;革兰阴性(G-)杆菌2866株,占61.6%。产超广谱β-内酰胺酶大肠杆菌和肺炎克雷伯菌2年平均检出率分别为36.5%、27.9%。G+球菌对青霉素、苯唑西林、头孢唑啉、阿莫西林/克拉维酸、红霉素、复方新诺明、环丙沙星的2年平均耐药率达84.5%;G-杆菌对氨苄西林2年平均耐药率达96.0%,对头孢噻肟、头孢吡肟、庆大霉素、复方新诺明、环丙沙星、氨曲南的2年平均耐药率达52.7%。结论:2年来,医院感染病原菌G-杆菌增加,G+球菌不变,真菌感染有逐年降低趋势。细菌耐药性不断增强,临床应加强对抗菌药物使用的干预。     

2004—2007年某医院1885株临床病原菌的分布与耐药分析

目的了解新乡市第一人民医院2004—2007年1885株临床常见病原菌分布及耐药情况。方法菌株鉴定采用复星公司FORTUNE.2000和珠海黑马生物工程有限公司全自动微生物鉴定系统,药敏试验用纸片扩散法（K-B法）。结果在1885株病原菌中革兰阴性杆菌60.3%,革兰阳性球菌35.7%,真菌4.0%。对革兰阴性杆菌耐药率较低的抗菌药物为亚胺培南、头胞他啶、阿米卡星、呋喃妥因等。某些常见抗菌药物,如头孢他啶、哌拉西林、左氧氟沙星、四环素等2004、2005、2006年耐药率逐年提高,2007年明显降低。对革兰阳性球菌耐药率较低的抗菌药物为万古霉素、亚胺培南、利福平等,青霉素、苯唑西林等2004、2005、2006年耐药率逐年提高,2007年明显降低。红霉素、阿奇霉素、复方新诺明、环丙沙星2006年已开始降低,亚胺培南、头孢唑林、克林霉素、利福平、四环素等有耐药率升高的趋势。结论开发抗菌药物、加强细菌的耐药性检测及强调抗菌药物的合理使用等,依然是今后抗感染界控制细菌耐药性蔓延的主要措施。