The application of information technology to regional,national, and global surveillance of antimicrobial resistance

Establishing local, national, and global surveillance networks for monitoring the dissemination of antimicrobial resistance and detecting the emergence of new resistance mechanisms has been recommended by the American Society for Microbiology Task Force on Antibiotic Resistance and other national organizations. While the need to develop and deploy surveillance strategies cannot be argued, the design and implementation of effective regional, national, and global surveillance networks is a daunting task with geographic, participatory, logistic, and funding challenges. Using information technology to capture, combine, collate, and analyze daily clinical microbiology laboratory data would seem to be a far more robust and logical approach to surveillance than traditional centralized studies that generally focus on only a few bacterial species or on isolates from a single body site. Information technology allows long-term, continuous tracking of antimicrobial resistance trends among large numbers of isolates over a broad range of species, and across entire regions or countries. The rationale for wanting to use networks of clinical laboratories for surveillance is obvious: susceptibility data are generated every day by thousands of laboratories located around the world, and most of these laboratories perform antimicrobial susceptibility testing on the bacterial species that pose the greatest public health problems. By virtue of information technology, large volumes of data can readily be managed and stored to allow timely and thorough analysis on institutional, regional, national, and global levels.     

Pathogen occurrence and antimicrobial resistance trends among urinary tract infection isolates in the Asia-Western Pacific Region: report from the SENTRY Antimicrobial Surveillance Program, 1998-1999

Worldwide surveillance of antimicrobial resistance among urinary tract pathogens is useful to determine important trends and geographical variation for common Gram-positive and -negative species. The most common causative uropathogens often have intrinsic or acquired resistance mechanisms which include ESBL production among enteric bacilli, multi-drug resistant staphylococci and non-fermentative Gram-negative bacilli such as Pseudomonas aeruginosa and Acinetobacter spp. and vancomycin-resistant Enterococcus spp. This study evaluates pathogen frequency and the resistance rates among urinary tract infection (UTI) pathogens in 14 medical centres in the Asia-Pacific region between 1998 and 1999. The isolates were referred to a central monitor for reference NCCLS broth microdilution testing, identification confirmation and patient demographic analysis. Over 50% of the 958 pathogens were Escherichia coli and Klebsiella spp. followed by P. aeruginosa, Enterococcus spp. and Enterobacter spp. Susceptibility for the three enteric bacilli was high for carbapenems (100%), 'fourth-generation' cephalosporins (cefepime 94.9-98.6%) and amikacin (> or = 93.0%). Beta-lactamase inhibitor compounds were more active against E. coli (piperacillin/tazobactam; > 90% susceptible) than the other two enteric species and all other tested agents had a narrower spectra of activity. The rank order of anti-pseudomonal agents was amikacin (91.5% susceptible)> imipenem > piperacillin/tazobactam > tobramycin > ceftazidime and cefepime (77.4 and 76.4% susceptible, respectively). Susceptibility to quinolones for the P. aeruginosa isolates was only 63.2-67.0%. Only one vancomycin-intermediate Enterococcus spp. (van C phenotype) was detected among the 103 strains tested. Newer fluoroquinolones (gatifloxacin; MIC(50), mg/l) were more potent against enterococci than ciprofloxacin (MIC(50), 2 mg/l) and high-level resistance to aminoglycosides was common (41.7%). The data presented are compared to studies of similar design from other areas which are part of the SENTRY surveillance network.     

Antibiotic resistance - is resistance detected by surveillance relevant to predicting resistance in the clinical setting?

Local, regional, national and global surveillance initiatives have several important functions, which include identifying shifts in antibiotic resistance, detecting the emergence of new resistance mechanisms and monitoring the impact of changes made to empiric prescribing, infection control and public health guidelines. Although the need for surveillance is indubitable and its use in the treatment of individual patients important, it cannot unequivocally predict outcomes in patients with infections. Treatment regimens for individual patients with suspected or demonstrated infections should be developed following consideration of symptoms, laboratory findings and relevant medical history, and in the context of appropriate local and widespread antibiotic resistance trends.     

Trends in linezolid susceptibility patterns: report from the 2002-2003 worldwide Zyvox Annual Appraisal of Potency and Spectrum (ZAAPS) Program

Linezolid is an important oxazolidinone antimicrobial for the treatment of infections caused by Gram-positive cocci, especially vancomycin-resistant enterococci and oxacillin-resistant Staphylococcus aureus (ORSA). Since its introduction, however, ribosomal mutations have been detected that produce resistance; thus, longitudinal surveillance remains necessary to monitor for emerging resistance in all geographic areas of oxazolidinone use. The 2003 Zyvox Annual Appraisal of Potency and Spectrum (ZAAPS) Program compared linezolid minimum inhibitory concentration (MIC) results with 13-15 comparator antimicrobial agents (8089 isolates) and also with results from an earlier surveillance period (2002). Sampling institutions in the United States of America (USA), Canada, Europe (seven nations), South America (three nations) and the Asia-Pacific (three nations) referred 200 Gram-positive cocci to the central laboratory for MIC processing and identification confirmation. Linezolid resistance (MIC > or = 8 mg/L) was established by alternative susceptibility testing methods as well as by ribosomal target characterisation. Concurrent drug use data were collected. Linezolid activity against the six major organism groups did not vary between years or geographic areas. In contrast, penicillin resistance increased 2% in Streptococcus pneumoniae; macrolide resistance was stable among beta-haemolytic streptococci (19-21%), but increased in S. pneumoniae (+2%); ORSA rates increased 4%; and vancomycin resistance in enterococci was present, but varied markedly by region. Non-clonal linezolid-resistant isolates were detected, each having the same G2576U 23S rRNA target mutation. Furthermore, the first linezolid-resistant, non-USA isolate (S. aureus in Greece) was observed, apparently related to linezolid use. In 2003, near complete activity for linezolid against Gram-positive isolates was again documented (99.93% susceptible) in the ZAAPS Program. Rare linezolid-resistant isolates were identified among enterococci, limited to USA strains. Limited correlations of linezolid resistance to drug use continues, with an average consumption rate of 0.63DDD/100 patient days (a 50% increase since 2002), and indicates the important role of hospital hygiene practice in preventing the dissemination of oxazolidinone resistances, should they be detected.     

The utility of hospital antibiograms as tools for guiding empiric therapy and tracking resistance. Insights from the Society of Infectious Diseases Pharmacists

Hospital antibiograms are commonly used to help guide empiric antimicrobial treatment and are an important component of detecting and monitoring trends in antimicrobial resistance. To serve these purposes, antibiograms must be constructed using standardized methods that allow inter- and intrahospital comparisons. Antibiograms that include surveillance cultures and duplicate bacterial isolates can overestimate rates of resistance. In 2002, the National Committee for Clinical Laboratory Standards (now known as the Clinical and Laboratory Standards Institute [CLSI]) published standards for constructing antibiograms. According to national surveys, many of the recommended elements of the CLSI document have not been fully adopted. In lieu of full compliance with CLSI standards, it is necessary that the methods used to construct antibiograms are clearly delineated. Antibiograms have several limitations, such as their inability to track emergence of resistance during therapy. The antibiogram can serve as a valuable tool in guiding antimicrobial therapy, but other patient factors, such as previous infection history and antibiotic use, also need to be considered. Additional data are needed for specialized applications of resistance analyses.     

Susceptibility to fluoroquinolones among commonly isolated Gram-negative bacilli in 2000: TRUST and TSN data for the United States. Tracking Resistance in the United States Today. The Surveillance Network

From January to May 2000, as part of the Tracking Resistance in the United States Today (TRUST) surveillance initiative, clinical isolates of Enterobacteriaceae (n=2519) and non-fermentative Gram-negatives (n=580) were prospectively collected from 26 hospital laboratories across the United States. Isolates were tested for susceptibility to three fluoroquinolones (ciprofloxacin, levofloxacin, gatifloxacin) and seven other agents. In addition, data for the same period were collected from The Surveillance Network (TSN) Database-USA, an electronic surveillance network that receives data from more than 200 laboratories in the US. Both surveillance methods produced similar results. Against isolates of Enterobacteriaceae, imipenem was the most active agent, followed by the fluoroquinolones; > or = 86.7% of isolates of all species of Enterobacteriaceae except Providencia spp. were susceptible to fluoroquinolones by TRUST and TSN surveillance. TRUST identified differences in susceptibility to the three fluoroquinolones of > or = 2% for Citrobacter spp., Enterobacter cloacae, Proteus mirabilis and Serratia marcescens. Isolates of P. mirabilis were considerably more susceptible to levofloxacin (94.0%) than to ciprofloxacin (87.7%) and gatifloxacin (87.7%). Other results from TRUST included Pseudomonas aeruginosa being slightly more susceptible to ciprofloxacin (73.5%) and levofloxacin (73.0%) than gatifloxacin (71.0%). Imipenem was the only compound with significant activity (95.1% susceptible, TRUST; 87.4% susceptible, TSN) against Acinetobacter baumannii, but it was inactive against Stenotrophomonas maltophilia. S. maltophilia isolates were more susceptible to levofloxacin and gatifloxacin (77.7-79.8%) than ciprofloxacin (29.7-33.0%). Against 513 urinary isolates of Escherichia coli in TRUST, levofloxacin, gatifloxacin and ciprofloxacin were equipotent. Age and gender had no clear effect on the activity of levofloxacin, ciprofloxacin or gatifloxacin. Similar results for all three fluoroquinolones were seen in outpatients and inpatients. TRUST and TSN data indicated that resistance rates had not changed appreciably for any compound studied since a similar study conducted in 1999. TRUST centralized in vitro and electronic (TSN) surveillance methods provided an effective strategy for monitoring trends in resistance.     

瑞典应对抗生素耐药性问题的国家治理经验及对我国的启示

目的 简述瑞典抗生素耐药性应对战略的机构设置、分工协作模式、应对措施,为我国抗生素耐药治理提供建议。方法 检索并梳理国内外关于瑞典抗生素耐药性应对战略文献。结果 瑞典抗生素耐药性应对战略包括：从国家和地方层面开展工作,建立抗生素使用监测体系,监测细菌耐药性趋势,设定抗生素处方量上限,预防医院感染,减少动物用抗生素,增加公众抗生素耐药性知识。结论 我国可以借鉴瑞典抗生素耐药性应对战略经验, 设立专门管理机构负责抗生素耐药治理工作;建立全国性监测网络;管理畜牧业抗生素使用;通过宣传教育规范公众及专业人员用药行为。     

Surveillance of susceptibility of clinical isolates to panipenem between 2000 and 2003

For the post-marketing surveillance of panipenem/betamipron (PAPM/BP, Carbenin), MICs of injectable beta-lactam antibacterials including PAPM against clinical isolates from 15 medical institutions all over Japan are measured yearly and the incidence rates of resistance in various species are also evaluated. In the first surveillance from June 2000 to March 2001, 1,356 isolates of 28 species were tested, 1,221 isolates of the same 28 species were tested in the second surveillance from April 2001 to March 2002, and 1,403 isolates of the same 28 species were tested in the third surveillance from April 2002 to March 2003. No remarkable changes in the activity of PAPM were observed in these surveillances spanning three years. The activity of PAPM in this study was comparable to that in the studies conducted before Carbenin was launched. This result suggests that PAPM still maintains potent activity. In these surveillances spanning three years, the incidence rates of resistance in various species were as follows (2000.6-2001.3 --> 2001.4-2002.3 --> 2002.4-2003.3): methicillin-resistant Staphylococcus aureus (39.3% --> 43.9% --> 47.3%), penicillin-intermediate Streptococcus pneumoniae (48.9% --> 44.2% --> 25.7%), penicillin-resistant S. pneumoniae (PRSP, 13.8% --> 26.3% --> 43.2%), extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (0.9% --> 0% --> 1.4%), ESBL-producing Klebsiella pneumoniae (3.4% --> 1.3% --> 3.1%), beta-lactamase-producing Haemophilus influenzae (19.2% --> 8.9% --> 42.9%), beta-lactamase-negative ampicillin-resistant H. influenzae (BLNAR, 22.1% --> 30.7% --> 33.0%), and metallo-beta-lactamase-producing Pseudomonas aeruginosa (1.0% --> 4.4% --> 1.0%). PAPM showed the most potent activity among tested drugs against PRSP, whose incidence rate increased notably. BLNAR, whose incidence rates also increased, exhibited low susceptibility to all tested drugs and metallo-beta-lactamase-producing P. aeruginosa also exhibited high resistance. The findings of this surveillance indicate that it is necessary to pay careful attention to the trends of resistant bacteria such as PRSP, BLNAR, and metallo-beta-lactamase producing strains.     

Non-invasive erythromycin-resistant pneumococcal isolates are more often non-susceptible to more antimicrobial agents than invasive isolates

Multiresistant Streptococcus pneumoniae infections are of great concern as treatment failures may occur with commonly used treatment regimens using β-lactams and macrolides. The proportion of non-susceptible S. pneumoniae differs from country to country. In Denmark, the proportion of invasive penicillin- or erythromycin-non-susceptible isolates is still low. The aim of this study was to characterise and compare invasive and non-invasive penicillin-non-susceptible and erythromycin-resistant pneumococcal isolates from the same geographic area and the same time period with respect to serotype and antibiotic susceptibility profile. We aimed to identify which serotypes were multiresistant among Danish isolates and to confirm or reject whether there was a difference in serotype distribution and resistance profiles between invasive and non-invasive isolates. We observed that non-invasive penicillin-non-susceptible pneumococci had higher serotype diversity than invasive isolates. This was not the case for erythromycin-resistant pneumococci. The dominant serotypes among non-susceptible invasive isolates were serotypes 9V and 14, whereas the dominant serotypes among non-susceptible non-invasive isolates were serotypes 19F, 14, 9V, 6B and non-typeable (NT). Non-invasive isolates were also more likely to be resistant to three or more antimicrobial agents than invasive isolates, however isolates being multiresistant were often co-resistant to the same antimicrobial agents.     

Pandrug-resistant Gram-negative bacteria: the dawn of the post-antibiotic era?

The evolving problem of antimicrobial resistance in Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae has led to the emergence of clinical isolates susceptible to only one class of antimicrobial agents and eventually to pandrug-resistant (PDR) isolates, i.e. resistant to all available antibiotics. We reviewed the available evidence from laboratory and clinical studies that reported on polymyxin-resistant and/or PDR P. aeruginosa, A. baumannii or K. pneumoniae clinical isolates. Eleven laboratory studies reported on isolates with resistance to polymyxins, three of which (including two surveillance studies) also included data regarding PDR isolates. In addition, two clinical studies (from Central and Southern Europe) reported on the clinical characteristics and outcomes of patients infected with PDR isolates. These data suggest that polymyxin-resistant or PDR P. aeruginosa, A. baumannii and K. pneumoniae clinical isolates are currently relatively rare. However, they have important global public health implications because of the therapeutic problems they pose. The fears for the dawn of a post-antibiotic era appear to be justified, at least for these three Gram-negative bacteria. We must increase our efforts to preserve the activity of available antibiotics, or at least expand as much as possible the period of their use, whilst intense research efforts should be focused on the development and introduction into clinical practice of new antimicrobial agents.     

Stabilization of penicillin resistance among Streptococcus pneumoniae isolated in Eastern Tennessee

Penicillin resistance among Eastern Tennessee isolates of Streptococcus pneumoniae has been increasing since the early 1990s. To maintain active surveillance of the prevalence of penicillin resistance among pneumococci isolated at our institution, antibiotic susceptibility testing was performed for 95 consecutive isolates and results were compared with those of strains examined 2 years earlier. The prevalence of penicillin resistance among local pneumococcal isolates may have stabilized in recent years.     

Prevalence and antimicrobial susceptibility patterns among gastroenteritis-causing pathogens recovered in Europe and Latin America and Salmonella isolates recovered from bloodstream infections in North America and Latin America: report from the SENTRY Antimicrobial Surveillance Program (2003)

Gastroenteritis-causing pathogens are the second leading cause of morbidity and mortality worldwide. Complicating the clinical diarrhoea syndrome is the emergence of antimicrobial resistance among the responsible bacterial pathogens. The reported increases in fluoroquinolone resistance in Salmonella, Shigella and Campylobacter have been extremely worrisome considering the primary role of ciprofloxacin as a treatment. In this study, 1479 bacterial isolates from gastroenteritis infections were collected in Europe and Latin America, which included Salmonella spp. (834; 56%), Shigella spp. (311; 21%), Campylobacter spp. (182; 12%) and Aeromonas spp. (72; 5%). The fluoroquinolones displayed the greatest activity against these pathogens, with only three non-Campylobacter spp. strains being non-susceptible using current Clinical and Laboratory Standards Institute (CLSI) breakpoint criteria. Whilst ciprofloxacin resistance in European and Latin American Salmonella was only 0.2% and 0.0%, respectively, a total of 16.2% and 12.9% of isolates were resistant to nalidixic acid, indicating possible first-step gyrA mutations. Among confirmed extended-spectrum beta-lactamase-producing Salmonella strains, CTX-M genes were detected in 15 originating from Russia. Erythromycin and azithromycin were the most potent agents tested against Campylobacter spp. (values of minimum inhibitory concentration for 90% of the organisms, 0.5 mg/L and 0.12 mg/L, respectively), with erythromycin displaying the highest susceptibility (91.1%). Salmonella isolates from bloodstream infections displayed antibiograms that were nearly identical to strains causing gastroenteritis. Considering the role that antimicrobial therapy plays in the management of moderate to severe bacterial gastroenteritis, global surveillance and local/national public health programmes can provide critical data illuminating the dissemination of resistance and guidance for empirical therapy.     

The use of cephalosporins for gonorrhea: the impending problem of resistance

Gonorrhea remains an important clinical and public health problem throughout the world. Gonococcal infections have historically been diagnosed by Gram stain and culture but are increasingly diagnosed through nucleic acid tests, thereby eliminating the opportunity for antimicrobial susceptibility testing. Gonococcal infections are typically treated with single-dose therapy with an agent found to cure > 95% of cases. Unfortunately, the gonococcus has repeatedly developed resistance to antimicrobials including sulfonamides, penicillin, tetracyclines and fluoroquinolones. This has now left third-generation cephalosporins as the lone class of antimicrobials recommended as first-line therapy for gonorrhea in some regions. However, resistance to oral third-generation cephalosporins has emerged and spread in Asia, Australia and elsewhere. The mechanism of this resistance seems to be associated with a mosaic penicillin binding protein (penA) in addition to other chromosomal mutations previously found to confer resistance to β-lactam antimicrobials (ponA, mtrR, penB, pilQ). Few good options exist or are in development for treating cephalosporin-resistant isolates, as most have had multidrug resistance. Preventing the spread of resistant isolates will depend on ambitious antimicrobial management programs, strengthening and expanding surveillance networks, and through effective sexually transmitted disease control and prevention.     

Surveillance of susceptibility of clinical isolates to cefpodoxime between 2000 and 2003

For the post-marketing surveillance of cefpodoxime proxetil (CPDX-PR, Banan), MICs of oral cephem antibacterials including CPDX against clinical isolates from 15 medical institutions all over Japan are measured yearly and the incidence rates of resistance in various species are also evaluated. In the first surveillance from June 2000 to March 2001, 1,091 isolates of 22 species were tested, 993 isolates of the same 22 species were tested in the second surveillance from April 2001 to March 2002, and 1,115 isolates of the same 22 species were tested in the third surveillance from April 2002 to March 2003. No remarkable changes in the activity of CPDX were observed against most of the species in these surveillances spanning three years and in comparison with that in the studies conducted before Banan was launched. In the study, CPDX as well as other cephem antibacterials showed a gradual decrease in activity against all the strains of Streptococcus pneumoniae and Haemophilus influenzae in proportion to the increase in the incidence rates of penicillin-resistant S. pneumoniae (PRSP) and beta-lactamase-negative ampicillin-resistant H. influenzae (BLNAR). A small percentage of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, which are high-resistant strains, were isolated. The findings of this surveillance indicate that it is necessary to pay careful attention to the trends of resistant bacteria such as PRSP, BLNAR, and ESBL-producing strains.     

Impact of travel on international spread of antimicrobial resistance

Antimicrobial resistance, an escalating problem worldwide, affects a broad range of human diseases. Excessive and inappropriate drug usage is the key driver for the emergence of resistant organisms. Travel, trade and mass migration form an important mode for their spread. The use of molecular biology provides the means of understanding the genesis and spread of the genes for drug resistance. Antimicrobial use in veterinary practice as food additives causes selection of resistant zoonotic pathogens that may spread to humans. Comprehensive surveillance systems should be designed and implemented at local and national levels and a national resistance surveillance database operationalized. There is also need for better regulation of the use of antibiotics and education of the medical fraternity, veterinarians and the public in the appropriate use of antimicrobials.     

Linezolid update: Stable in vitro activity following more than a decade of clinical use and summary of associated resistance mechanisms

Linezolid, approved for clinical use since 2000, has become an important addition to the anti-Gram-positive infection armamentarium. This oxazolidinone drug has in vitro and in vivo activity against essentially all Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). The in vitro activity of linezolid was well documented prior to its clinical application, and several ongoing surveillance studies demonstrated consistent and potent results during the subsequent years of clinical use. Emergence of resistance has been limited and associated with invasive procedures, deep organ involvement, presence of foreign material and mainly prolonged therapy. Non-susceptible organisms usually demonstrate alterations in the 23S rRNA target, which remain the main resistance mechanism observed in enterococci; although a few reports have described the detection of cfr-mediated resistance in Enterococcus faecalis. S. aureus isolates non-susceptible to linezolid remain rare in large surveillance studies. Most isolates harbour 23S rRNA mutations; however, cfr-carrying MRSA isolates have been observed in the United States and elsewhere. It is still uncertain whether the occurrences of such isolates are becoming more prevalent. Coagulase-negative isolates (CoNS) resistant to linezolid were uncommon following clinical approval. Surveillance data have indicated that CoNS isolates, mainly Staphylococcus epidermidis, currently account for the majority of Gram-positive organisms displaying elevated MIC results to linezolid. In addition, these isolates frequently demonstrate complex and numerous resistance mechanisms, such as alterations in the ribosomal proteins L3 and/or L4 and/or presence of cfr and/or modifications in 23S rRNA. The knowledge acquired during the past decades on this initially used oxazolidinone has been utilized for developing new candidate agents, such as tedizolid and radezolid, and as linezolid patents soon begin to expire, generic brands will certainly become available. These events will likely establish a new chapter for this successful class of antimicrobial agents.     

New approaches to the prevention and treatment of severe S. aureus infections

Staphylococcus aureus is a virulent pathogen that is currently a major cause of community-acquired infections, as well as infections in hospitalized patients. Morbidity and mortality due to S. aureus infections, such as sepsis, osteomyelitis, septic arthritis and infective endocarditis, remain high despite the use of newer antibiotics. Of major concern, methicillin resistance in S. aureus isolates has increased dramatically worldwide, especially among nosocomial isolates; this phenotype may be associated with resistance to other antistaphylococcal compounds, including vancomycin. This increase in prevalence of multiantibiotic resistance in S. aureus is a major public health concern. Currently, there is an intense focus on the development of novel vaccines for the prevention of S. aureus infections in high-risk populations and on new antimicrobial classes for the therapy of established S. aureus infections.     

Evolution of penicillin and erythromycin co-resistance in Streptococcus pneumoniae in Spain

The temporal dynamics of penicillin and erythromycin co-resistance in Streptococcus pneumoniae based on two extensive multicentre Spanish surveillance SAUCE studies (1996-1997 and 1998-1999) is presented. Erythromycin resistance among penicillin non-susceptible isolates seems to have reached a limit as evidenced by a null increase between the two surveys, whereas it is growing among penicillin-susceptible pneumococci.     

多重耐药临床菌株中整合子结构的检测与分析

目的研究广州暨南大学附属第一医院2004年部分临床菌株样本的整合子及其基因盒的分布特性。方法多重PCR检测与细菌耐药关系密切的1、2、3类整合酶基因,进一步对阳性样本可变区的基因盒序列鉴定分析。结果随机抽取109株临床菌株,整合酶阳性检出率为97.2%(106/109),其中1类整合酶阳性菌100株(91.7%),2类整合酶阳性菌1株(0.92%),此外有5株(4.6%)同时检出1、2类整合酶,没有检测到3类整合酶;基因盒鉴定结果显示,插入基因盒以dfrA(甲氧苄氨嘧啶耐药相关)和aadA(氨基糖苷类耐药相关)基因家族为主,也在少数菌株中发现了aacA4、cmlA1、catB3以及sat1基因盒。其中又以dfrA12、orfF和aadA2组合最为常见,耐药基因盒PCR扩增片段为1913bp(64.6%);此外,还发现了同时存在两种整合子结构的菌株。结论整合子普遍存在于临床菌株中,可通过基因水平转移在不同菌属间传播,提示各医药单位必须加强耐药监测及合理选择抗菌药物,以减少多重耐药细菌的发生和发展。     

Fluoroquinolone resistance in the hospital versus outpatient setting

The Lomefloxacin International Surveillance Trial (LIST) is an in vitro testing program specifically designed to assess the antimicrobial activity of lomefloxacin against a wide range of clinical isolates from hospitals, clinics, and laboratories worldwide. Lomefloxacin was used as a representative quinolone to assess susceptibility patterns of fresh clinical isolates for new fluoroquinolones. Between June 1989 and December 1990, hospitals and clinics in France contributed zone-diameter data (5 mug disk) on approximately 45 000 clinical isolates. Data were collected by a processing center in the USA and were analyzed to identify susceptibility patterns by region and by country in addition to identifying trends in high-grade fluoroquinolone resistance. This analysis showed that an unusual and widespread pattern of fluoroquinolone resistance was observed for isolates tested at tertiary-care centers in France. In order to assess whether high levels of fluoroquinolone usage in these centers might be responsible for this level of resistance, a group of six French Community Clinics was added to the testing program in 1990. From May 1990 until April 1991, these clinics contributed data on almost 4500 strains to the testing program. In most cases, there was little or no difference between susceptibility patterns obtained in French Community Clinics and University Hospitals. The only statistically significant difference noted was for Staphylococcus aureus: only 70% of French University Hospital strains were susceptible to lomefloxacin compared with 92% of Community Clinic strains (p<0.05). This result is in agreement with other studies of new fluoroquinolones carried out in the USA and worldwide. Many of the fluoroquinolone-resistant strains of Staphylococcus aureus were also resistant to methicillin and other anti-bacterial drugs.