Extended-spectrum beta-lactamases (ESbLs): characterization, epidemiology and detection

Beta-lactamases of Enterobacteriaceae are the most important mechanism of resistance against beta-lactam drugs. Two types of beta-lactamases can confer resistance against 3rd generation cephalosporins. Chromosomally mediated beta-lactamases are inducible and are not inhibited by clavulanic acid. Resistance due to these enzymes is non-transferable. The 2nd type of enzyme is plasmid-mediated beta-lactamases, which are inhibited by clavulanic acid. These enzymes are more important clinically as these can be transferred between various species of Enterobacteriaceae. These enzymes are called extended-spectrum beta-lactamases (ESBLs). ESBL-producing Enterobacteriaceae have been responsible for numerous outbreaks of infection throughout the world and pose challenging infection control issues. Antibacterial choice is often complicated by multi-resistance. ESBLs can confer resistance against all beta-lactam drugs except carbapenems and cephamycins. Nursing home patients may be an important reservoir of ESBL-containing multiple antibiotic-resistant organisms. Use of broad-spectrum oral antibiotics and probably poor infection control practices may facilitate spread of this plasmid-mediated resistance. In addition to known populations at risk, ambulatory patients with chronic conditions represent another patient population that may harbor ESBL-producing organisms. Various methods can be used for detection of ESBLs in the laboratory. These tests include double disc diffusion test, Vitek ESBL test, E Tests, MIC Determination, genetic method, and isoelectric focusing (IEF).     

Extended-spectrum beta-lactamases in Taiwan: epidemiology, detection, treatment and infection control.

Extended-spectrum beta-lactamases (ESBLs) efficiently hydrolyze extended-spectrum beta-lactams such as cefotaxime, ceftriaxone, ceftazidime, and aztreonam. ESBLs are most often plasmid-mediated. In Taiwan, the prevalence of ESBLs in bacteria has risen, ranging from 8.5 to 29.8% in Klebsiella pneumoniae and 1.5 to 16.7% in Escherichia coli isolates. The most prevalent types of ESBLs are SHV-5, SHV-12, CTX-M-3, and CTX-M-14 in isolates of K. pneumoniae and E. coli, with differences between institutions. SHV-12 and CTX-M-3 have been reported as the most common ESBLs in isolates of Enterobacter cloacae and Serratia marcescens, respectively. Molecular epidemiology studies suggest that the ESBL-encoding genes have been disseminated either by proliferation of epidemic strains or by transfer of plasmids carrying the resistance traits. The current ESBL screen guidelines of the Clinical and Laboratory Standards Institute (formerly National Committee for Clinical Laboratory Standards) are issued for E. coli, Klebsiella spp., and Proteus mirabilis. Owing to the lack of standard methods, it remains difficult to assure the presence of ESBL in an isolate co-harboring an AmpC beta-lactamase, particularly in cases where the latter is produced in larger amounts than the former. Empirical therapy with piperacillin-tazobactam to replace third-generation cephalosporins may help to reduce the occurrence of ESBLs in an institution with a high prevalence of ESBL producers. Carbapenems remain the drugs of choice for serious infections caused by ESBL-producing organisms. To retard the selection for carbapenem-resistant bacteria, 7-alpha-methoxy beta-lactams or fourth-generation cephalosporins can be therapeutic alternatives for mild-to-moderate infections provided that the pharmacokinetic and pharmacodynamic target can be easily achieved.     

Aging in the 21st century

In this introductory article, a rapid overview is presented of the recent increase of life expectancy and its limitations mainly by unhealthy living habits: overeating, fast food, lack of exercise. The strong increase of obesity worldwide with its metabolic consequences might well limit or even decrease human life expectancy. The part of the population over 65 who have access to “anti-aging medicine” represents however another challenge to experimental and clinical gerontology, further discussed in later articles of this issue.     

Complement analysis in the 21st century

Complement analysis in the clinic is usually associated with the quantification of C3 and C4, measurement of C1-inhibitor and screening for complement activity. These analyses have been available in routine diagnostic laboratories for decades. In recent years, however, the field of complement analysis has expanded considerably, with the introduction of novel assays to detect complement activation products, and spreading still further towards genetic analysis to reveal the basis of complement deficiencies and identify mutations and polymorphisms associated with defined diseases such as atypical haemolytic uraemic syndrome and age related macular degeneration. Here we review the current status of complement analysis, including assays for the quantification of complement activity and complement activation products, together with genetic methods for the detection of deficiencies, mutations and polymorphisms. This is an area where significant developments have been made recently, paralleling the research advances into the role of complement in human disease. It is clear, however, that there is a need for consensus and standardisation of analytical methods. This will be a major challenge for the complement society in the future.     

A clinician in the 21st century

At the beginning of the 21st century, clinical practice faces new challenges associated with very fast scientific and technological advances. Societies have also changed and current conditions demand modernization of clinical practice. Now we acknowledge the need for a patient-centered medical practice. Novel technologies will also participate in this new social fabric. This is the new clinical practice of the 21st century.     

Clinical laboratory in the 21st century

Alvin Toffler has predicted that the "Third Wave" will be a society which be decentralized, diversified and customized, computer-dependent. Medical care and also clinical laboratory will be revolutionalized in a more or less similar direction to that predicted by him. Laboratory physicians and scientists should try to improve laboratory services, particularly establishment of adequate normal values, common expression of various laboratory results, introduction of medical decision making and recommended guideline for laboratory use in primary health care.     

Asthma treatment in the 21st century

Asthma treatment is evolving as we enter the 21st century. This review focuses on several different areas of asthma treatment now in evolution. These include: (1) the proper role of various asthma controllers--either already approved or under investigation--besides inhaled corticosteriods in asthma therapy; (2) the potential role for immune and cytokine modulation for asthma therapy; (3) the potential role for pharmacogenetics in asthma therapy; and (4) whether single-inhaler therapy with a combination of an inhaled corticosteriod and a long-acted beta-agonist could be used for both maintenance and rescue in patients with asthma.     

Complement analysis in the 21st century

Complement analysis in the clinic is usually associated with the quantification of C3 and C4, measurement of C1-inhibitor and screening for complement activity. These analyses have been available in routine diagnostic laboratories for decades. In recent years, however, the field of complement analysis has expanded considerably, with the introduction of novel assays to detect complement activation products, and spreading still further towards genetic analysis to reveal the basis of complement deficiencies and identify mutations and polymorphisms associated with defined diseases such as atypical haemolytic uraemic syndrome and age related macular degeneration. Here we review the current status of complement analysis, including assays for the quantification of complement activity and complement activation products, together with genetic methods for the detection of deficiencies, mutations and polymorphisms. This is an area where significant developments have been made recently, paralleling the research advances into the role of complement in human disease. It is clear, however, that there is a need for consensus and standardisation of analytical methods. This will be a major challenge for the complement society in the future.     

Hospital cleaning in the 21st century

More evidence is emerging on the importance of the clinical environment in encouraging hospital infection. This review considers the role of cleaning as an effective means to control infection. It describes the location of pathogen reservoirs and methods for evaluating hospitals’ cleanliness. Novel biocides, antimicrobial coatings and equipment are available, many of which have not been assessed against patient outcome. Cleaning practices should be tailored to clinical risk, given the wide-ranging surfaces, equipment and building design. There is confusion between nursing and domestic personnel over the allocation of cleaning responsibilities and neither may receive sufficient training and/or time to complete their duties. Since less labourious practices for dirt removal are always attractive, there is a danger that traditional cleaning methods are forgotten or ignored. Few studies have examined detergent-based regimens or modelled these against infection risk for different patient categories. Fear of infection encourages the use of powerful disinfectants for the elimination of real or imagined pathogens in hospitals. Not only do these agents offer false assurance against contamination, their disinfection potential cannot be achieved without the prior removal of organic soil. Detergent-based cleaning is cheaper than using disinfectants and much less toxic. Hospital cleaning in the 21st century deserves further investigation for routine and outbreak practices.