Is There an Ecological Relationship between Rates of Antibiotic Resistance of Species of the Genus Streptococcus?

The relationship between resistance to antibiotics on the part of Streptococcus pneumoniae and Streptococcus pyogenes was studied by comparing different prevalences of resistance among hospitals obtained from a recent microbiological surveillance of community-acquired respiratory tract infections. A high correlation for erythromycin resistance was found between S. pneumoniae isolates from lower respiratory tract infections and S. pyogenes isolates collected from pharyngeal swabs.     

High frequency of multiresistant respiratory tract pathogens at community level in South India

Objective: To describe the patterns of antibiotic susceptibility of outpatient strains of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in the district of Pondicherry in South India.
Methods: The antibiotic susceptibilities of 94 S. pneumoniae , 97 H. influenzae and 104 M. catarrhalis strains, collected from outpatients with respiratory tract infections, were determined by disk diffusion and Etest.
Results: Resistance or reduced susceptibility to trimethoprim-sulfamethoxazole was found in 67% of S. pneumoniae , 53% of H. influenzae and 24% of M. catarrhalis strains. Thirty-seven per cent of S. pneumoniae and 39% of H. influenzae strains were resistant or showed reduced susceptibility to tetracycline. Reduced susceptibility to penicillin was found in 6% of S. pneumoniae strains. Overall, 10% of S. pneumoniae and 38% of H. influenzae strains showed reduced susceptibility to ≥3 antibiotics. Comparisons between the antibiotic susceptibility patterns of the Indian strains and a corresponding collection of strains from Sweden indicate that the susceptibility of the native susceptible population is independent of geographic origin.
Conclusions: The findings indicate high consumption of tetracycline and trimethoprim-sulfamethoxazole in the area, which emphasizes the need for surveillance of the pattern of antibiotic susceptibility among respiratory tract pathogens at community level in developing countries and for the implementation of local guidelines for rational use of antibiotics.     

Limiting the spread of resistant pneumococci: biological and epidemiologic evidence for the effectiveness of alternative interventions

Streptococcus pneumoniae infections are a leading cause of respiratory illness in young children, the elderly, and persons with chronic medical conditions. The emergence of multidrug-resistant pneumococci has compromised the effectiveness of antibiotic therapy for pneumococcal infections. As antibiotic-resistant strains increase in prevalence, there is a need for interventions that minimize the spread of resistant pneumococci. In this review we provide a framework for understanding the spread of pneumococcal resistance and evaluate proposed interventions to reduce this spread. Pneumococci differ from many drug-resistant pathogens because asymptomatic carriers play a key role in transmission of resistant strains and the genes encoding resistance are spread primarily by transformation and conjugative transposons. Evidence suggests that modifications of treatment regimens that have proved effective at limiting resistance in other pathogens may not prevent the spread of pneumococcal resistance. In contrast, programs encouraging more judicious antibiotic use have been shown to be effective. Additionally, a newly developed conjugate pneumococcal vaccine holds great potential as an "antiresistance vaccine" that simultaneously reduces the burden of invasive disease and the prevalence of resistant strains. Several areas of future epidemiologic and laboratory research hold promise to contribute to the reduced spread of pneumococcal resistance.     

Epidemiological studies on drug resistance in Streptococcus pneumoniae in Hungary: an update for the 1990s

The aim of this study was to give an overview about the epidemiological features of pneumococcal resistance in Hungary in the 1990s, and to assess the clinical relevance of drug resistance in Streptococcus pneumoniae primarily in upper respiratory tract infections and the role of risk factors in the acquisition of resistant strains. In Hungary, resistance in S. pneumoniae decreased slightly in recent years, but is still highly prevalent (around 40% to penicillin) compared to the prevalence in western and northern neighboring countries. The prevalent serogroup among resistant strains is 19A, as it was several years ago. In 76 case histories studies, chronic underlying diseases associated with long hospitalization, episodes of earlier hospitalization, and antibiotic therapy were found more frequently if the patient was infected with a resistant strain than with a susceptible one, indicating that these factors promote the acquisition of drug-resistant S. pneumoniae. Resistant S. pneumoniae modified the course of infection by prolonging the duration of hospitalization, making more courses of antibiotics necessary, including parenteral drugs, as well as more invasive interventions such as myringotomy and sinus puncture. These data justify the clinical relevance of resistance, particularly in the upper respiratory tract infections.     

The prevalence of antibiotic resistance in bacterial respiratory pathogens from Norway is low

Objectives   To determine the degree of bacterial susceptibility to the most commonly used drugs for respiratory infections in Norway, and to find if bacterial resistance is emerging.
Methods   Clinical isolates of Streptococcus pneumoniae , Haemophilus influenzae and group A streptococci from respiratory tract specimens and from the eye were collected from different parts of Norway during two study periods. During the first period (1993–1994), three laboratories, covering 15% of the Norwegian population, participated. During the second study period in 1997, five laboratories, covering 27% of the population, collected respiratory isolates. In total, 494 isolates of S. pneumoniae , 696 isolates of H. influenzae and 694 isolates of group A streptococci were included in the study. The study population comprised children and adults attending hospital and general practice. Bacterial susceptibility was determined by the E test, and breakpoints were according to the National Committee for Clinical Laboratory Standards (NCCLS).
Results   The prevalence of bacterial resistance was low, and we observed no significant increase in bacterial resistance between the two study periods. In 1997, only 0.6% of pneumococci had decreased susceptibility to penicillin, 1.6% of group A streptococci were resistant to erythromycin, and 6.7% of all isolates of H. influenzae produced β -lactamase.
Conclusions   The prevalence of antibiotic resistance in respiratory pathogens in Norway is low.     

Epidemiology and sensitivity to antibiotics in paediatric respiratory infections over a 4-year period. Retrospective study of 460 H. influenzae,S. pneumoniae and M. catarrhalis strains

H. influenzae, S. pneumoniae and M. catarrhalis are the most common bacterial pathogens causing respiratory infections in children. Resistance to antibiotics may vary according to the geographical area. It is therefore important that the resistance pattern of such pathogens is determined by surveillance studies carried out both on a national scale and by individual laboratories. In this study, we determined retrospectively the prevalence of H. influenzae, S. pneumoniae and M. catarrhalis in upper respiratory tract infections involving subjects of paediatric age, with reference to the type of clinical sample (pharingeal swab and nasal swab), symptomatology and age group. Moreover, for the above micro-organisms the pattern of sensitivity to antibiotics was assessed. In the observation period (January 1996-December 1999), at the day hospital of the Paediatric Pneumology Division of the Gaslini Institute in Genova, in 476 patients between 0 and 15 years of age a total of 460 respiratory pathogens were isolated: 164 S. pneumoniae strains, 163 of H. influenzae (96 belonging to type B and 67 non-attributable to any type) and 133 of M. catarrhalis. As regards sensitivity to antibiotics, ceftriaxone and amoxycillin/clavulanic acid proved to be the most active molecules in all the studied strains.     

Antimicrobial susceptibility to levofloxacin and other antibacterial agents among common respiratory pathogens—a Brazilian perspective from the GLOBAL Surveillance Initiative 2001–2002

The GLOBAL (Global Landscape On Bactericidal Activity of Levofloxacin) Surveillance programme monitored antimicrobial susceptibility patterns of the key respiratory tract pathogens Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis collected in Brazil during 1997-1998, 1999-2000 and 2001-2002. Penicillin and azithromycin resistance among S. pneumoniae strains increased from 1997-1998, reaching 7.9% and 9.5%, respectively, in 2001-2002. Although decreasing by 4.9% since the previous study, trimethoprim-sulphamethoxazole resistance remained high at 33.7%. Concurrent resistance to penicillin, azithromycin and trimethoprim-sulphamethoxazole was seen in 2.9% of the S. pneumoniae isolates collected. Levofloxacin remained extremely active against S. pneumoniae, with 0.3% resistance reported in 1997-1998 and 0% resistance in 1999-2000 and 2001-2002. beta-Lactamase production in H. influenzae was > 10% in all three studies, with correspondingly high rates of ampicillin resistance. Trimethoprim-sulphamethoxazole was the least active agent tested against H. influenzae, with resistance rates of > 40% recorded in all three studies. All H. influenzae isolates were susceptible to cefuroxime, ceftriaxone, azithromycin and levofloxacin. Of the M. catarrhalis isolates, 98.0% in 1997-1998, 98.0% in 1999-2000 and 81.8% in 2001-2002 were beta-lactamase-positive. The continued high prevalence of antimicrobial resistance in Brazil underscores the importance of current surveillance initiatives. Levofloxacin, a fluoroquinolone prescribed widely for respiratory tract infections, continued to show potent activity against key respiratory pathogens.     

Prevalence of antibiotic resistance in <Emphasis Type="BoldItalic">Escherichia coli</Emphasis>: overview of geographical,temporal, and methodological variations

The increase in bacterial antibiotic resistance is of major concern worldwide, but pertinent epidemiologic studies have used strongly divergent approaches and are widely scattered in the literature. The aim of this study was to conduct a systematic review of studies reporting on the prevalence of antibiotic resistance in Escherichia coli in different parts of the world. Studies published from 1970 to 2006 on the prevalence of E. coli resistance were identified by a systematic Medline research and reviewed with respect to characteristics of the study design and study population, the method of resistance detection, and the prevalence of resistance. The prevalence of resistance to specific antibiotics was highly variable in different populations and in different countries and ranged from 0 to 100%. The prevalence of resistance reported in studies from Middle and South America, Spain, and Turkey was higher than that reported in the USA and Central Europe. Moreover, a tendency towards higher prevalence rates of resistance in recent years was observed. The findings indicate a need for regular monitoring of antimicrobial susceptibility rates in different human and animal populations by standardized sampling and measurement procedures. Such monitoring would help identify relevant factors that contribute to the spread of resistant pathogens and would support the prudent use of antibiotics.     

Introduction: Evolving needs in respiratory tract infections

Two issues that have become clinically relevant to the treatment of pneumonia over the past few years are the development of antibiotic resistance among respiratory pathogens and the increasing importance of the atypical respiratory pathogens— Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella spp.
Resistance has become an important issue in Streptococcus pneumoniae , methicillin-resistant Staphylococcus aureus and Gram-negative rods. The ways by which bacteria become resistant to antibiotics include production of antibiotic-modifying enzymes, reduced access to target sites, efflux of antibiotic, change in the bacterial target site and the bypassing of inhibited pathways. In Streptococcus pneumoniae that are penicillin resistant, the mechanism is through alteration of the target site for penicillins (penicillin-binding proteins) and this may also confer resistance to some cephalosporins. Multidrug resistance has also been reported in some strains of pneumococci. Of particular concern is resistance to macrolides mediated by the ermAM gene, which also confers resistance to lincosamides and streptogramin-B drugs. In Staphylococcus aureus , resistance to virtually all β-lactam drugs is mediated by acquisition of the mecA gene, which codes for the drug-resistant β-lactam target PBP2a.
Antimicrobials are now needed that have enhanced activity against aerobic Gram-negative rods, atypical respiratory pathogens and Gram-positive cocci.     

Is antimicrobial resistance also subject to globalization?

In recent years one of the more alarming aspects of clinical microbiology has been the dramatic increase in the incidence of resistance to antibacterial agents among pathogens causing nosocomial as well as community-acquired infections. There are profound geographic differences in the incidence of resistance among pathogens of the respiratory tract, only some of which can be explained by the local use of antibiotics. A high percentage of Moraxella catarrhalis strains produce β -lactamase and are thus resistant to many β -lactam antibiotics. In contrast, β -lactamase production among strains of Haemophilus influenzae rarely reaches more than 30% around the world. Methicillin-resistance in Staphylococcus aureus is a common and increasing problem in hospitals but its extent varies both locally and nationally. Resistance is usually associated with the local spread of resistant strains. High standards of hygiene in hospitals can prevent the spread of such strains but once established they can be difficult to eradicate. Although Streptococcus pyogenes remains highly susceptible to penicillins, even after many decades of their use, resistance to macrolides has occurred. This resistance can rise and fall. Although the increase of macrolide resistance in S. pyogenes can often be associated with an increase in the use of these drugs, this is not always so. In some cases it has been shown to be caused by the spread of one or more resistant clones. Eradication of these clones can reduce the level of resistance markedly. Resistance to both macrolides and penicillins among strains of Streptococcus pneumoniae is seen world-wide but is highly variable from country to country. Local habits of drug usage may play a part. In Italy, for example, there is preference for the use of parenteral third-generation cephalosporins for some severe infections and there is a corresponding low level of penicillin-resistance among pneumococci.     

Mucosal immunization against respiratory bacterial pathogens

Bacterial respiratory diseases remain a major cause of morbidity and mortality throughout the world. The young and the elderly are particularly susceptible to the pathogens that cause these diseases. Therapeutic approaches remain dependent upon antibiotics contributing to the persistent increases in antibiotic resistance. The main causes of respiratory disease discussed in this review are Mycobacterium tuberculosis, Corynebacterium diphtheriae, Bordatella pertussis, Streptococcus pneumoniae, non-typeable Haemophilus influenzae, Moraxella catarrhalis and Pseudomonas aeruginosa. All these organisms initiate disease at the mucosal surface of the respiratory tract and thus the efficacy of the host's response to infection needs to be optimal at this site. Vaccines available for diseases caused by many of these pathogens have limitations in accessibility or efficacy, highlighting the need for improvements in approaches and products. The most significant challenges in both therapy and prevention of disease induced by bacteria in the respiratory tract remain the development of non-injectable vaccines and delivery systems/immunization regimens that improve mucosal immunity.     

The changing epidemiology of severe infections in the ICU

Data on the epidemiology of severe infection in the intensive care unit (ICU) can be used to monitor the effect of preventive measures and changes in policy or procedures. The most common risk factors associated with ICU-acquired infection include length of stay, antibiotic usage, catheterization and use of other invasive devices. The most frequent infections encountered in ICU patients include lower respiratory tract infections (especially pneumonia) and bacteremia, in addition to urinary tract infections and wound infections. Streptococcus pneumoniae, Haemophilus influenzae , methicillin susceptible Staphylococcus aureus and Enterobacteriaceae are most often implicated in community-acquired and early onset ICU-acquired infections, whereas late onset infection is more likely to be caused by pathogens which are more refractory to treatment, such as Enterobacter spp., Serratia spp., Pseudomonas aeruginosa, Acinetobacter spp. and methicillin-resistant S. aureus (MRSA). The pathogen spectrum also varies according to the site of infection, with Gram-positive bacteria being most frequently isolated in bacteremia and wound infections, whereas Gram-negative bacteria are prevalent in late-onset pneumonia and urinary tract infections. The prevalence of Gram-positive pathogens in bacteremia has increased over the past 20 years, mainly because of the increased isolation of coagulase-negative staphylococci (CNS) and enterococci. This is most probably due to the selective pressure exerted by the use of broad-spectrum antibiotics, such as the third-generation cephalosporins and fluoroquinolones, which are generally more potent against Gram-negative than Gram-positive bacteria, and to the increased use of invasive devices.
The increasing isolation frequency of Gram-positive pathogens in severe ICU infections has resulted in greater usage of vancomycin, which may account for the rising incidence of vancomycin-resistant enterococci.     

Serogroup distribution and antimicrobial resistance of nasopharyngeal isolates of <Emphasis Type="Italic">Streptococcus pneumoniae</Emphasis> among Beijing children with upper respiratory infections (2000–2005)

The aims of this study were to estimate pneumococcal carriage rate, antimicrobial resistance and serogroup distribution of nasopharyngeal isolates of Streptococcus pneumoniae among children with acute upper respiratory infections (AURIs) aged 1 month to 5 years attending outpatient department of the Beijing Children's Hospital between 2000 and 2005. Susceptibilities to penicillin, amoxicillin-clavulanic acid, ceftriaxone, cefuroxime, cefaclor, erythromycin, tetracycline, sulfamethoxazole-trimethoprim and chloramphenicol were assessed using the E-test and disc diffusion. We also analyzed the correlation between antibiotic consumption and rates of resistance. The prevalence of penicillin-nonsusceptible pneumococci increased from 26% during 2000-2001 and 21% during 2002-2003 to 31.5% in 2004-2005. The percentage of S. pneumoniae resistant to cefaclor and cefuroxime increased from about 6% during 2000-2001 to about 23% during 2004-2005 (P<0.01). The frequency of resistance to erythromycin ranged from 87% to 94%. Tetracycline and co-trimoxazole resistance rates were greater than 80%. We conclude that resistance rates for most antibiotics are increasing, possibly due to misues of antibiotics in the hospital setting. However, chloramphenicol resistance was found to decrease, which correlated with the cessation of chloramphenicol administration in 1999. Pneumococcal strains (n=519) were analyzed by serogroup, and only 296 were found to be seven-valent pneumococcal conjugate vaccine-related serotype isolates. This serotype distribution is important for surveillance of the new conjugate vaccine.     

老干部保健病房感染病原菌分布及耐药性分析

目的分析2008-2011年老干部保健病房病原菌的分布特点及对临床常规抗菌药物的耐药特征,为临床合理用药提供参考。方法回顾性分析2008-2011年老干部保健病房分离出的342株病原菌,采用法国梅里埃公司生产的VITEK-2 Compact全自动微生物分析仪做鉴定和药敏试验。结果从2008年1月至2011年12月,共检出病原菌342株,其中革兰阴性杆菌248株,占72.5%;革兰阳性球菌51株,占14.9%;真菌43株,占12.57%;革兰阴性杆菌占病原菌的绝大多数;检出前5位的病原菌分别是大肠埃希菌、肺炎克雷伯菌、白色假丝酵母菌、铜绿假单胞菌、屎肠球菌。4年间革兰阴性杆菌对亚胺培南的敏感性最好,耐药率〈15.4%,其次是阿米卡星,耐药率〈18.9%,二者耐药率已出现了逐年上升的趋势;对氨苄西林的耐药率最高〉84.1%。糖肽类和恶唑烷酮类抗菌药物对革兰阳性球菌始终保持高敏感性。感染部位以泌尿系（41.5%）最常见,其次是下呼吸道（39.2%）。结论老干部保健病房常见病原菌均具有较高的耐药性,对多种抗菌药物耐药率呈逐年上升趋势;加强老年病房的细菌及耐药性监测,合理使用抗菌药物,预防耐药菌株的产生及扩散。     

下呼吸道感染病原菌分布及耐药性分析

目的 了解医院呼吸科下呼吸道感染的病原菌分布及耐药性情况。方法 收集呼吸科下呼吸道感染住院患者的痰标本,进行统计分析。结果 检测出革兰阴性菌占78.25%,前四位为肺炎克雷伯菌、铜绿假单胞菌、鲍曼不动杆菌、大肠埃希菌;真菌占13.49%,以白色念珠菌为主。革兰阳性菌占8.26%,以金黄色葡萄球菌为主;药敏试验显示,革兰阴性菌中,妥布霉素耐药率最低,其次是阿米卡星。结论 呼吸科细菌耐药现象严重,加强病原菌耐药性监测,合理使用抗菌药物。     

An international multicenter study of antimicrobial resistance and typing of hospital Staphylococcus aureus isolates from 21 laboratories in 19 countries or states

During 1996, 4065 consecutive Staphylococcus aureus strains from different patients were collected in 21 worldwide hospital laboratories. The strains, their resistance pattern, and hospital demographic data were forwarded to Statens Serum Institut where the strains were typed and data analyzed. Resistance patterns varied by region and resistance to other antibiotics than methicillin were mainly related to the occurrence of methicillin resistance, except for mupirocin, rifampicin, and fusidic acid. Methicillin-resistant S. aureus (MRSA) occurred with low levels in hospitals in Northern Europe (<1%), increasing levels in middle-European countries, United States, New Zealand, and Australia (6-22%), and very high levels in Southern European countries as well as in parts of the United States, Asia, and South Africa (28-63%). MRSA found in large hospitals were more resistant to other antibiotics than MRSA found in smaller hospitals serviced by the same laboratory. No difference in resistance levels was seen for methicillin-susceptible S. aureus (MSSA) isolated in large or small hospitals. Intensive Care Units had the highest level of MRSA. Strains from the lower respiratory tract showed the highest resistance levels and blood isolates the lowest. A dominating MRSA clone was found in hospitals with an MRSA frequency of more than 10%. Pulsed-field gel electrophoresis (PFGE) typing recognized several of these clones as international epidemic MRSA (E-MRSA). All MSSA isolates were phage typed (typeability 85.4%) and divided in seven major phage patterns. Isolates of all patterns were found in all hospitals except one, indicating that the MSSA seldom represented the spread of clones within the hospital. The comparison should evaluate the prevalence of community-acquired MRSA and identify internationally E-MRSA. The present study gives a snapshot of the MRSA situation, but it is important to build up a continuous national and international surveillance, because MRSA is a global socioeconomic problem. Global infection control procedures, including rational antibiotic use, should be agreed on. The accompanying paper will address the issue of antibiotic consumption and MRSA.