Resistance surveillance of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis isolated in Asia and Europe, 1997-1998

The Association between Transformation Ability and Antimicrobial Resistant Potential in Haemophilus influenzae

The prevalence of quinolone low-susceptible Haemophilus influenzae has increased in Japan. Low quinolone susceptibility is caused by point mutations in target genes; however, it can also be caused by horizontal gene transfer via natural transformation. In this study, we examined whether this horizontal gene transfer could be associated with resistance to not only quinolones but also other antimicrobial agents. Horizontal transfer ability was quantified using the experimental transfer assay method for low quinolone susceptibility. Further, the association between horizontal transfer ability and resistance to β-lactams, the first-choice drugs for H. influenzae infection, was investigated. The transformation efficiency of 50 clinical isolates varied widely, ranging from 102 to 106 colony forming unit (CFU) of the colonies obtained by horizontal transfer assay. Efficiency was associated with β-lactam resistance caused by ftsI mutations, indicating that strains with high horizontal transfer ability acquired quinolone low-susceptibility as well as β-lactam resistance more easily. Strains with high transformation efficiency increased the transcript level of comA, suggesting that enhanced com operon was associated with a high DNA uptake ability. Overall, this study revealed that the transformation ability of H. influenzae was associated with multiple antimicrobial resistance. Increase in the number of strains with high horizontal transformation ability has raised concerns regarding the rapid spread of antimicrobial-resistant H. influenzae.

Establishing Statistical Equivalence of Data from Different Sampling Approaches for Assessment of Bacterial Phenotypic Antimicrobial Resistance

To assess phenotypic bacterial antimicrobial resistance (AMR) in different strata (e.g., host populations, environmental areas, manure, or sewage effluents) for epidemiological purposes, isolates of target bacteria can be obtained from a stratum using various sample types. Also, different sample processing methods can be applied. The MIC of each target antimicrobial drug for each isolate is measured. Statistical equivalence testing of the MIC data for the isolates allows evaluation of whether different sample types or sample processing methods yield equivalent estimates of the bacterial antimicrobial susceptibility in the stratum. We demonstrate this approach on the antimicrobial susceptibility estimates for (i) nontyphoidal Salmonella spp. from ground or trimmed meat versus cecal content samples of cattle in processing plants in 2013-2014 and (ii) nontyphoidal Salmonella spp. from urine, fecal, and blood human samples in 2015 (U.S. National Antimicrobial Resistance Monitoring System data). We found that the sample types for cattle yielded nonequivalent susceptibility estimates for several antimicrobial drug classes and thus may gauge distinct subpopulations of salmonellae. The quinolone and fluoroquinolone susceptibility estimates for nontyphoidal salmonellae from human blood are nonequivalent to those from urine or feces, conjecturally due to the fluoroquinolone (ciprofloxacin) use to treat infections caused by nontyphoidal salmonellae. We also demonstrate statistical equivalence testing for comparing sample processing methods for fecal samples (culturing one versus multiple aliquots per sample) to assess AMR in fecal Escherichia coli These methods yield equivalent results, except for tetracyclines. Importantly, statistical equivalence testing provides the MIC difference at which the data from two sample types or sample processing methods differ statistically. Data users (e.g., microbiologists and epidemiologists) may then interpret practical relevance of the difference.IMPORTANCE Bacterial antimicrobial resistance (AMR) needs to be assessed in different populations or strata for the purposes of surveillance and determination of the efficacy of interventions to halt AMR dissemination. To assess phenotypic antimicrobial susceptibility, isolates of target bacteria can be obtained from a stratum using different sample types or employing different sample processing methods in the laboratory. The MIC of each target antimicrobial drug for each of the isolates is measured, yielding the MIC distribution across the isolates from each sample type or sample processing method. We describe statistical equivalence testing for the MIC data for evaluating whether two sample types or sample processing methods yield equivalent estimates of the bacterial phenotypic antimicrobial susceptibility in the stratum. This includes estimating the MIC difference at which the data from the two approaches differ statistically. Data users (e.g., microbiologists, epidemiologists, and public health professionals) can then interpret whether that present difference is practically relevant.

Antibiotic Prescribing for Patients with Upper Respiratory Tract Infections by Emergency Physicians in a Singapore Tertiary Hospital

Objective

Despite the paucity of supporting evidence, the use of antibiotics in the management of upper respiratory tract infections (URTI) remains a persistent and worrying trend worldwide. This survey study set out to examine the antibiotic prescribing profile of emergency physicians for patients diagnosed with URTI at a local tertiary hospital.

Methods

Patients seeking treatment for URTI at the emergency department in the year 2001 were identified by their ICD-9 code. The electronic medical records of a random sample of these patients were reviewed. Patients with the following documented findings were excluded: (a) a duration of more than 7 days between disease onset and date of consultation, (b) prior antibiotic usage or medical consultation, (c) presentation of purulent sputum and/or purulent nasal discharge, and (d) existing medical conditions requiring antibiotic treatment/prophylaxis. Chi-square and multivariate analyses were performed to assess the association of patient-related factors with antibiotic prescribing.

Results

Of a random sample of 488 cases of URTI, inappropriate antibiotic prescribing was observed in 24% of cases (95% CI 20%, 28%). Significant associations were observed between antibiotic prescribing and month of consultation, patients' temperature and symptom of rhinorrhoea.

Conclusion

A substantial proportion of emergency department patients with URTI received antibiotics despite the lack of evidence supporting the drugs' effectiveness. Appropriate interventions to promote evidence-based prescribing amongst emergency physicians are required to reduce the extent of inappropriate antibiotic prescribing as well as to ensure the longevity of antibiotic effectiveness.

Clinical practice guideline (update): adult sinusitis

OBJECTIVE

This update of a 2007 guideline from the American Academy of Otolaryngology--Head and Neck Surgery Foundation provides evidence-based recommendations to manage adult rhinosinusitis, defined as symptomatic inflammation of the paranasal sinuses and nasal cavity. Changes from the prior guideline include a consumer added to the update group, evidence from 42 new systematic reviews, enhanced information on patient education and counseling, a new algorithm to clarify action statement relationships, expanded opportunities for watchful waiting (without antibiotic therapy) as initial therapy of acute bacterial rhinosinusitis (ABRS), and 3 new recommendations for managing chronic rhinosinusitis (CRS).

PURPOSE

The purpose of this multidisciplinary guideline is to identify quality improvement opportunities in managing adult rhinosinusitis and to create explicit and actionable recommendations to implement these opportunities in clinical practice. Specifically, the goals are to improve diagnostic accuracy for adult rhinosinusitis, promote appropriate use of ancillary tests to confirm diagnosis and guide management, and promote judicious use of systemic and topical therapy, which includes radiography, nasal endoscopy, computed tomography, and testing for allergy and immune function. Emphasis was also placed on identifying multiple chronic conditions that would modify management of rhinosinusitis, including asthma, cystic fibrosis, immunocompromised state, and ciliary dyskinesia.

ACTION STATEMENTS

The update group made strong recommendations that clinicians (1) should distinguish presumed ABRS from acute rhinosinusitis (ARS) caused by viral upper respiratory infections and noninfectious conditions and (2) should confirm a clinical diagnosis of CRS with objective documentation of sinonasal inflammation, which may be accomplished using anterior rhinoscopy, nasal endoscopy, or computed tomography. The update group made recommendations that clinicians (1) should either offer watchful waiting (without antibiotics) or prescribe initial antibiotic therapy for adults with uncomplicated ABRS; (2) should prescribe amoxicillin with or without clavulanate as first-line therapy for 5 to 10 days (if a decision is made to treat ABRS with an antibiotic); (3) should reassess the patient to confirm ABRS, exclude other causes of illness, and detect complications if the patient worsens or fails to improve with the initial management option by 7 days after diagnosis or worsens during the initial management; (4) should distinguish CRS and recurrent ARS from isolated episodes of ABRS and other causes of sinonasal symptoms; (5) should assess the patient with CRS or recurrent ARS for multiple chronic conditions that would modify management, such as asthma, cystic fibrosis, immunocompromised state, and ciliary dyskinesia; (6) should confirm the presence or absence of nasal polyps in a patient with CRS; and (7) should recommend saline nasal irrigation, topical intranasal corticosteroids, or both for symptom relief of CRS. The update group stated as options that clinicians may (1) recommend analgesics, topical intranasal steroids, and/or nasal saline irrigation for symptomatic relief of viral rhinosinusitis; (2) recommend analgesics, topical intranasal steroids, and/or nasal saline irrigation) for symptomatic relief of ABRS; and (3) obtain testing for allergy and immune function in evaluating a patient with CRS or recurrent ARS. The update group made recommendations that clinicians (1) should not obtain radiographic imaging for patients who meet diagnostic criteria for ARS, unless a complication or alternative diagnosis is suspected, and (2) should not prescribe topical or systemic antifungal therapy for patients with CRS.

Comparative Activity of Telithromycin Against Macrolide-Resistant Isolates ofStreptococcus pneumoniae:Results of Two Years of the PROTEKT Surveillance Study

The increase in resistance to macrolides has been linked with increasing use of these agents as empirical therapy for community-acquired respiratory tract infections (CARTIs). As part of the ongoing PROTEKT (Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin) surveillance program, over 7600 Streptococcus pneumoniae isolates were collected worldwide from 1999-2001 and evaluated for macrolide resistance. Globally, macrolide resistance was 31-33%, with considerable inter-country variation (<10-88%) and particularly high prevalence in the Far East (>71%). In Europe, France had the most resistant isolates (>53%). The highest rates of macrolide resistance were seen in 0-2 year olds. Co-resistance to clindamycin (64%) and all beta-lactams (14-79%) was seen among macrolide-resistant isolates, but >99% of these isolates were susceptible to telithromycin, vancomycin and linezolid. There was considerable variation in the prevalence of erm(B) (56-64%) and mef(A) (30-35%): erm(B) was prevalent in Europe and mef(A) in North America. Globally, 5-7% isolates carried both mechanisms (erm(B)+mef(A)); of these, 47-65% were from South Korea. These double resistance isolates were >90% resistant to the beta-lactams, except amoxicillin-clavulanate. Clindamycin was active against >98% mef(A) but poorly active against erm(B) and erm(B)+mef(A) isolates. Telithromycin, vancomycin and linezolid were highly active (>99.5%) across all three genotypes.

CONCLUSIONS

In vitro, telithromycin, vancomycin and linezolid are highly active against antibiotic-resistant strains of S. pneumoniae. Telithromycin may be a useful therapeutic alternative to macrolides for the treatment of CARTIs.

Clinical practice guideline for the diagnosis and management of acute bacterial sinusitis in children aged 1 to 18 years

OBJECTIVE

To update the American Academy of Pediatrics clinical practice guideline regarding the diagnosis and management of acute bacterial sinusitis in children and adolescents.

METHODS

Analysis of the medical literature published since the last version of the guideline (2001).

RESULTS

The diagnosis of acute bacterial sinusitis is made when a child with an acute upper respiratory tract infection (URI) presents with (1) persistent illness (nasal discharge [of any quality] or daytime cough or both lasting more than 10 days without improvement), (2) a worsening course (worsening or new onset of nasal discharge, daytime cough, or fever after initial improvement), or (3) severe onset (concurrent fever[temperature ≥39°C/102.2°F] and purulent nasal discharge for at least 3 consecutive days). Clinicians should not obtain imaging studies of any kind to distinguish acute bacterial sinusitis from viral URI, because they do not contribute to the diagnosis; however, a contrast-enhanced computed tomography scan of the paranasal sinuses should be obtained whenever a child is suspected of having orbital or central nervous system complications. The clinician should prescribe antibiotic therapy for acute bacterial sinusitis in children with severe onset or worsening course. The clinician should either prescribe antibiotic therapy or offer additional observation for 3 days to children with persistent illness. Amoxicillin with or without clavulanate is the firstline treatment of acute bacterial sinusitis. Clinicians should reassess initial management if there is either a caregiver report of worsening(progression of initial signs/symptoms or appearance of new signs/symptoms) or failure to improve within 72 hours of initial management.If the diagnosis of acute bacterial sinusitis is confirmed in a child with worsening symptoms or failure to improve, then clinicians may change the antibiotic therapy for the child initially managed with antibiotic or initiate antibiotic treatment of the child initially managed with observation.

CONCLUSIONS

Changes in this revision include the addition of a clinical presentation designated as “worsening course,” an option to treat immediately or observe children with persistent symptoms for 3 days before treating, and a review of evidence indicating that imaging is not necessary in children with uncomplicated acute bacterial sinusitis.

Serotype distribution and antimicrobial resistance of Streptococcus pneumoniae isolates causing invasive diseases from Shenzhen Children's Hospital

Objective

To provide guidance for clinical disease prevention and treatment, this study examined the epidemiology, antibiotic susceptibility, and serotype distribution of Streptococcus pneumoniae (S. pneumoniae) associated with invasive pneumococcal diseases (IPDs) among children less than 14 years of age in Shenzhen, China.

Materials and Methods

All the clinical strains were isolated from children less than 14 years old from January 2009 to August 2012. The serotypes and antibiotic resistance of strains of S. pneumoniae were determined using the capsular swelling method and the E-test.

Results

A total of 89 strains were isolated and 87 isolates were included. The five prevailing serotypes were 19F (28.7%), 14 (16.1%), 23F (11.5%), 19A (9.2%) and 6B (6.9%). The most common sequence types (ST) were ST271 (21.8%), ST876 (18.4%), ST320 (8.0%) and ST81 (6.9%) which were mainly related to 19F, 14, 19A and 23F, respectively. The potential coverage by 7-, 10-, and 13-valent pneumococcal conjugate vaccine were 77.0%, 77.0%, and 89.7%, respectively. Among the 87 isolates investigated, 11.5% were resistant to penicillin, and for meningitis isolates, the resistance rate was 100%. Multi-drug resistance (MDR) was exhibited by 49 (56.3%) isolates. Eighty-four isolates were resistance to erythromycin, among which, 56 (66.7%) carried the ermB gene alone and 28 (33.3%) expressed both the ermB and mefA/E genes.

Conclusions

The potential coverage of PCV13 is higher than PCV7 and PCV10 because high rates of serotypes 19A and 6A in Shenzhen. The clinical treatment of IPD needs a higher drug concentration of antibiotics. Continued surveillance of the antimicrobial susceptibility and serotypes distribution of IPD isolates may be necessary.

A Five-year Review on the Etiology and Antimicrobial Susceptibility Pattern of Otitis Media Pathogens in Jordanian Children

OBJECTIVE

This study aimed to identify the bacteriological agents of otitis media in Jordanian children and to assess the in vitro susceptibility of these isolates to commonly used antibiotics.

METHODS

Retrospective analysis of consecutive samples submitted for microbiological evaluation from outpatients children aged between 6 months and 15 years who were clinically diagnosed with otitis media and were treated at Princess Rahma Hospital in North Jordan between January 2005 and December 2009.

RESULTS

A total of 724 isolates were recovered from cultures obtained from 863 children patients giving an isolation rate of 83.8%. The male and female isolate ratio was (1.26:1.0). The most common bacterial species isolated were S. aureus (59.9%) followed by Streptococcus pneumoniae (22.4%), Pseudomonas (7.7%), E. coli (5.9%), Klebsiella spp. (3.1%) and Proteus spp. (0.9%). The most of S. aureus isolates were susceptible to vancomycin (94.0%) and gentamicin (87.3%). Streptococcus organisms were susceptible in highest percentage to amoxicillin-clavulanic acid (87.1%). Gram-negative isolates were highly susceptible to ciprofloxacin (83.5%) and gentamicin (79.8%). Among all isolates, vancomycin was the most effective antimicrobial agent with susceptibility rate of 83.9%, whereas cefixime showed the lowest susceptibility rate of 39.7%.

CONCLUSIONS

S. aureus isolates were the most frequent bacteria isolated from otitis media and were highly sensitive to vancomycin and gentamicin, while gram-negative isolates were more sensitive to ciprofloxacin and gentamicin.

Global fluoroquinolone resistance epidemiology and implictions for clinical use

This paper on the fluoroquinolone resistance epidemiology stratifies the data according to the different prescription patterns by either primary or tertiary caregivers and by indication. Global surveillance studies demonstrate that fluoroquinolone resistance rates increased in the past years in almost all bacterial species except S. pneumoniae and H. influenzae, causing community-acquired respiratory tract infections. However, 10 to 30% of these isolates harbored first-step mutations conferring low level fluoroquinolone resistance. Fluoroquinolone resistance increased in Enterobacteriaceae causing community acquired or healthcare associated urinary tract infections and intraabdominal infections, exceeding 50% in some parts of the world, particularly in Asia. One to two-thirds of Enterobacteriaceae producing extended spectrum β-lactamases were fluoroquinolone resistant too. Furthermore, fluoroquinolones select for methicillin resistance in Staphylococci. Neisseria gonorrhoeae acquired fluoroquinolone resistance rapidly; actual resistance rates are highly variable and can be as high as almost 100%, particularly in Asia, whereas resistance rates in Europe and North America range from <10% in rural areas to >30% in established sexual networks. In general, the continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some guidelines, for example, treatment of urinary tract, intra-abdominal, skin and skin structure infections, and traveller's diarrhea, or even precludes the use in indications like sexually transmitted diseases and enteric fever.

Comparison of Clarithromycin and Amoxicillin/Clavulanic Acid for Community-Acquired Pneumonia in an Era of Drug-Resistant Streptococcus pneumoniae

OBJECTIVE

To compare the safety and efficacy of clarithromycin and amoxicillin/clavulanic acid in patients with community-acquired pneumonia due to penicillin-resistant and/or macrolide-resistant Streptococcus pneumoniae, by selecting clinical investigators who practice in study populations from geographic areas in which a high incidence of resistant strains is reported by surveillance.

DESIGN AND SETTING

Prospective, randomised, investigator-blinded, multicentre study conducted in 45 sites in primary-care and referral centre settings.

PATIENTS AND INTERVENTIONS

327 ambulatory patients diagnosed with radio-graphically confirmed community-acquired pneumonia administered clarithromycin 500mg immediate-release or amoxicillin/clavulanic acid 875mg/125mg twice daily for 7 days.

MAIN OUTCOME MEASURES AND RESULTS

Similarly high clinical cure rates were observed among evaluable patients in both treatment groups at the test-of-cure visit (28-35 days post-treatment): 92% (114/124) for clarithromycin and 91% (117/129) for amoxicillin/clavulanic acid. Of 85 S. pneumoniae strains isolated pretreatment, four (5%) were classified as resistant to macrolides (one mefA, two ermB, and one ermB + mefA) and eight (9%) had reduced susceptibility to penicillin. The overall eradication rate for pathogens isolated from bacteriologically and clinically evaluable patients was 91% for clarithromycin and 93% for amoxicillin/clavulanic acid, and 89% and 92%, respectively, for S. pneumoniae strains. The rates of resolution and/or improvement in clinical signs and symptoms and radiological improvement were similar with clarithromycin to those with amoxicillin/clavulanic acid, as was overall incidence of adverse events.

CONCLUSION

A 7-day course of clarithromycin immediate-release was similar to amoxicillin/clavulanic acid based on high rates (>90%) of clinical cure, radiological improvement and pathogen eradication among ambulatory-care patients with community-acquired pneumonia. As the resistance rate at baseline was low, no conclusion could be made about clarithromycin's efficacy for infections caused by macrolide-resistant S. pneumoniae. Both treatments were well tolerated.

Serotype distribution and antibiotic resistance of 140 pneumococcal isolates from pediatric patients with upper respiratory infections in Beijing, 2010

In the present study, the serotype distribution and antibiotic resistance of S. pneumoniae from pediatric patients with upper respiratory infections in Beijing, 2010 were described. 140 pneumococcal isolates were obtained, and the prevailing five serotypes were 19F (18.6%), 23F (9.3%), 14 (9.3%), 15 (9.3%), and 6A (7.1%). The vaccine coverage of PCV7, PCV10, and PCV13 were 43.6%, 43.6%, and 60.0%, respectively. According to the CLSI 2010 criteria, 99.3% of the S. pneumoniae isolates were susceptible to penicillin. The resistance rates to erythromycin and azithromycin were 96.4% and 97.1%, respectively. Meanwhile, 64.3% (90/140) of all pneumococcal isolates were multidrug-resistant S. pneumoniae (MDRSP). PCV13 covered 68.9% (62/90) of MDRSP strains, whereas it was 47.8% (43/90) for PCV7. ErmB was the dominant macrolide-resistance gene, whereas 30.4% pneumococcal isolates expressed both ermB and mefA. No isolate expressed ermTR. The potential coverage of PCV13 is higher than PCV7 and PCV10 because high rates of serotypes 6A and 19A, and the conjugate vaccines could prevent the spread of MDRSP. S. pneumoniae is still sensitive to penicillin. The resistance rate of S. pneumoniae to macrolides is high and ermB is the dominant macrolide-resistance gene in China, so continued surveillance of the antimicrobial susceptibility of S. pneumoniae may be necessary.

Antibacterial susceptibility testing in the clinical laboratory

This article familiarizes the clinician with the principles of bacterial susceptibility testing and reporting to facilitate communication with the clinical microbiology laboratory. As resistance continues to emerge among a wide range of clinically relevant bacteria, the complexity of this communication increases. This updated version provides an overview of the important susceptibility concerns for most commonly isolated bacterial pathogens.

Treatment of bacterial meningitis: an overview of Cochrane systematic reviews

BACKGROUND

Acute bacterial meningitis (ABM) is a rapidly developing acute inflammation of leptomeninges and underlying subarachnoid cerebrospinal fluid (CSF). ABM is caused by bacteria and has a case fatality rate of 20-30%. Most prevalent causes of ABM are Neisseria meningitis, Streptococcus pneumoniae and Haemophilus influenzae. The aim of this paper is to summarize the main findings from Cochrane systematic reviews that have considered the evidence for treatments of ABM.

METHODS

We searched the Cochrane Library (issue 1, 2007) for relevant reviews using 'meningitis' as a search term. The titles of all the search results were examined to select reviews on treatment of ABM. The full text of each of the selected reviews was studied to summarize the evidence available in Cochrane systematic reviews.

RESULTS

We found three Cochrane reviews that focused specifically on the treatment of ABM, addressing empiric antibiotic therapy, fluid therapy and effects of adjuvant corticosteroids respectively. No statistically significant difference was found between third generation cephalosporins and conventional antibiotics in the combined endpoint of death or deafness (risk difference (RD) -1%, 95% CI -4% to +2%). However, culture positivity of CSF at 10-48 h was significantly higher in the conventional antibiotic group and diarrhoea was significantly more common in the cephalosporin group. When third generation cephalosporins are not available, ampicillin-chloramphenicol combination may be used as an alternative empiric treatment, however both resistance pattern as well as availability should be considered while prescribing empiric therapy of community acquired ABM. The fluid therapy review found too few studies to provide any robust conclusion. In settings with high mortality rates and where patients present late, use of intravenous maintenance fluids seems preferable to a restricted fluid intake. The efficacy of adjuvant corticosteroids varied between high- and low-income countries suggesting greater mortality reduction in high-income countries (RR 0.74, 95% CI 0.52-1.05) than in low-income countries (RR 0.87, 95% CI 0.72-1.05) and a beneficial effect on severe hearing loss in high-income countries (RR 0.32, 95% CI 0.18-0.57), whereas, sparse data in low-income countries (RR 1.04, 95% CI 0.66-1.63). A four-day regimen of dexamethasone should be given preferably before or with the first dose of antibiotics for cases of ABM from high-income countries.

CONCLUSION

In presence of sensitive organisms, third generation cephalosporins and conventional antibiotics lead to similar outcomes. More studies are needed to determine the antimicrobial resistance pattern against various antibiotics in rural and remote areas of developing as well as developed countries. To assess the effectiveness of either restricting or maintenance fluids in populations where patients present early and on death and disability when mortality rates are low, large trials should be conducted. More trials are needed to assess the use of adjuvant dexamethasone for ABM in low-income countries.

Causative agent distribution and antibiotic therapy assessment among adult patients with community acquired pneumonia in Chinese urban population

BACKGROUND

Knowledge of predominant microbial patterns in community-acquired pneumonia (CAP) constitutes the basis for initial decisions about empirical antimicrobial treatment, so a prospective study was performed during 2003-2004 among CAP of adult Chinese urban populations.

METHODS

Qualified patients were enrolled and screened for bacterial, atypical, and viral pathogens by sputum and/or blood culturing, and by antibody seroconversion test. Antibiotic treatment and patient outcome were also assessed.

RESULTS

Non-viral pathogens were found in 324/610 (53.1%) patients among whom M. pneumoniae was the most prevalent (126/610, 20.7%). Atypical pathogens were identified in 62/195 (31.8%) patients carrying bacterial pathogens. Respiratory viruses were identified in 35 (19%) of 184 randomly selected patients with adenovirus being the most common (16/184, 8.7%). The nonsusceptibility of S. pneumoniae to penicillin and azithromycin was 22.2% (Resistance (R): 3.2%, Intermediate (I): 19.0%) and 79.4% (R: 79.4%, I: 0%), respectively. Of patients (312) from whom causative pathogens were identified and antibiotic treatments were recorded, clinical cure rate with beta-lactam antibiotics alone and with combination of a beta-lactam plus a macrolide or with fluoroquinolones was 63.7% (79/124) and 67%(126/188), respectively. For patients having mixed M. pneumoniae and/or C. pneumoniae infections, a better cure rate was observed with regimens that are active against atypical pathogens (e.g. a beta-lactam plus a macrolide, or a fluoroquinolone) than with beta-lactam alone (75.8% vs. 42.9%, p = 0.045).

CONCLUSION

In Chinese adult CAP patients, M. pneumoniae was the most prevalent with mixed infections containing atypical pathogens being frequently observed. With S. pneumoniae, the prevalence of macrolide resistance was high and penicillin resistance low compared with data reported in other regions.

Otitis Media: A Review, with a Focus on Alternative Treatments

Otitis media (OM) is the accumulation of fluids in the middle ear, with or without symptoms of inflammation. The infection is caused by dysfunction or obstruction of the eustachian tube and is most commonly diagnosed in children under the age of two. The microbiology of OM differs, with Streptococcus pneumoniae, non-typeable Haemophilus influenzae and Moraxella catarrhalis the most commonly isolated pathogens. The emergence of penicillin-resistant Strep. pneumoniae, β-lactamase-producing strains, Haem. influenzae and Mor. catarrhalis is a major concern and health care costs associated with treatment are substantial, especially in cases of unresponsive treatment as a result of incorrect diagnosis. Alternative treatments such as vaccines and a nasal spray containing α-haemolytic streptococci with antimicrobial activity against OM pathogens, have been developed. The rationale behind such treatments is to induce an appropriate immune response against the pathogens and decrease bacterial colonisation in the nasopharynx. Another approach may be treatment with bacteriocins (natural antimicrobial peptides) or bacteriocin-like inhibitory substances (BLIS) produced by lactic acid bacteria. We have recently described an antibacterial peptide produced by Enterococcus mundtii ST4SA and have published on bacteriocins (enterocins) with antibacterial and antiviral activity. This review discusses the condition OM, summarises current methods used to treat the infection, and suggests alternative safe and natural treatments that need to be explored.

Antimicrobial susceptibility of respiratory tract pathogens in Japan during PROTEKT years 1-5 (1999-2004)

Susceptibility to a range of antimicrobial agents was determined among isolates of Streptococcus pneumoniae, Streptococcus pyogenes, and Haemophilus influenzae collected in 12 centers throughout Japan during years 1-5 (the respiratory seasons of 1999-2004) of the longitudinal Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin study. The most frequent source of isolates of S. pneumoniae was from patients with community-acquired pneumonia (CAP) (25.3%). Reduced susceptibility to penicillin or erythromycin resistance was common among S. pneumoniae isolates (30.9-44.5% and 77.2-81.9%, respectively). The macrolide MIC(50) for S. pneumoniae was >or=128 microg/ml (azithromycin and erythromycin) and >or=64 microg/ml (clarithromycin). The erm(B) genotype accounted for the most erythromycin-resistant isolates in each study year. H. influenzae isolates were most commonly derived from patients with CAP (26.2%). The proportion of H. influenzae isolates that were beta-lactamase positive ranged between 4.3% and 9.7%. The prevalence of beta-lactamase-negative ampicillin-resistant isolates increased from 0.4% to 2.6% between years 1 and 4 then to 19.7% in year 5. S. pyogenes isolates were highly susceptible to most antimicrobial agents except macrolides and tetracycline. Telithromycin was highly active against all three pathogens examined throughout the study.

Rapid identification of penicillin and macrolide resistance genes and simultaneous quantification of Streptococcus pneumoniae in purulent sputum samples by use of a novel real-time multiplex PCR assay

We evaluated a real-time quantitative PCR combined with a multiplex PCR assay for the quantification of Streptococcus pneumoniae and the simultaneous detection of drug-resistant genes by gel-based PCR, using purulent sputum samples. This assay correctly quantified S. pneumoniae and identified their penicillin and erythromycin susceptibilities directly from samples within 3 h.

Connection between trimethoprim-sulfamethoxazole use and resistance in Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis

The association between trimethoprim-sulfamethoxazole use and resistance among the major respiratory tract pathogens was investigated by comparing regional consumption of the drug to regional resistance in the following year in 21 central hospital districts in Finland. A total of 23,530 Streptococcus pneumoniae isolates, 28,320 Haemophilus influenzae isolates, and 14,138 Moraxella catarrhalis isolates were tested for trimethoprim-sulfamethoxazole susceptibility during the study period (1998-2004). Among the S. pneumoniae isolates, a statistically significant connection was found between regional consumption and resistance. No statistically significant connection was found between regional trimethoprim-sulfamethoxazole use and resistance among H. influenzae and M. catarrhalis isolates. According to our results, it seems that only in pneumococci can the development of trimethoprim-sulfamethoxazole resistance be influenced by restricting its use. However, trimethoprim-sulfamethoxazole remains an important antimicrobial agent because of its reasonable price. Hence, resistance to trimethoprim-sulfamethoxazole among these pathogens needs continuous monitoring.

Clinical practice guideline: adult sinusitis

OBJECTIVE

This guideline provides evidence-based recommendations on managing sinusitis, defined as symptomatic inflammation of the paranasal sinuses. Sinusitis affects 1 in 7 adults in the United States, resulting in about 31 million individuals diagnosed each year. Since sinusitis almost always involves the nasal cavity, the term rhinosinusitis is preferred. The guideline target patient is aged 18 years or older with uncomplicated rhinosinusitis, evaluated in any setting in which an adult with rhinosinusitis would be identified, monitored, or managed. This guideline is intended for all clinicians who are likely to diagnose and manage adults with sinusitis.

PURPOSE

The primary purpose of this guideline is to improve diagnostic accuracy for adult rhinosinusitis, reduce inappropriate antibiotic use, reduce inappropriate use of radiographic imaging, and promote appropriate use of ancillary tests that include nasal endoscopy, computed tomography, and testing for allergy and immune function. In creating this guideline the American Academy of Otolaryngology-Head and Neck Surgery Foundation selected a panel representing the fields of allergy, emergency medicine, family medicine, health insurance, immunology, infectious disease, internal medicine, medical informatics, nursing, otolaryngology-head and neck surgery, pulmonology, and radiology.

RESULTS

The panel made strong recommendations that 1) clinicians should distinguish presumed acute bacterial rhinosinusitis (ABRS) from acute rhinosinusitis caused by viral upper respiratory infections and noninfectious conditions, and a clinician should diagnose ABRS when (a) symptoms or signs of acute rhinosinusitis are present 10 days or more beyond the onset of upper respiratory symptoms, or (b) symptoms or signs of acute rhinosinusitis worsen within 10 days after an initial improvement (double worsening), and 2) the management of ABRS should include an assessment of pain, with analgesic treatment based on the severity of pain. The panel made a recommendation against radiographic imaging for patients who meet diagnostic criteria for acute rhinosinusitis, unless a complication or alternative diagnosis is suspected. The panel made recommendations that 1) if a decision is made to treat ABRS with an antibiotic agent, the clinician should prescribe amoxicillin as first-line therapy for most adults, 2) if the patient worsens or fails to improve with the initial management option by 7 days, the clinician should reassess the patient to confirm ABRS, exclude other causes of illness, and detect complications, 3) clinicians should distinguish chronic rhinosinusitis (CRS) and recurrent acute rhinosinusitis from isolated episodes of ABRS and other causes of sinonasal symptoms, 4) clinicians should assess the patient with CRS or recurrent acute rhinosinusitis for factors that modify management, such as allergic rhinitis, cystic fibrosis, immunocompromised state, ciliary dyskinesia, and anatomic variation, 5) the clinician should corroborate a diagnosis and/or investigate for underlying causes of CRS and recurrent acute rhinosinusitis, 6) the clinician should obtain computed tomography of the paranasal sinuses in diagnosing or evaluating a patient with CRS or recurrent acute rhinosinusitis, and 7) clinicians should educate/counsel patients with CRS or recurrent acute rhinosinusitis regarding control measures. The panel offered as options that 1) clinicians may prescribe symptomatic relief in managing viral rhinosinusitis, 2) clinicians may prescribe symptomatic relief in managing ABRS, 3) observation without use of antibiotics is an option for selected adults with uncomplicated ABRS who have mild illness (mild pain and temperature <38.3 degrees C or 101 degrees F) and assurance of follow-up, 4) the clinician may obtain nasal endoscopy in diagnosing or evaluating a patient with CRS or recurrent acute rhinosinusitis, and 5) the clinician may obtain testing for allergy and immune function in evaluating a patient with CRS or recurrent acute rhinosinusitis.

DISCLAIMER

This clinical practice guideline is not intended as a sole source of guidance for managing adults with rhinosinusitis. Rather, it is designed to assist clinicians by providing an evidence-based framework for decision-making strategies. It is not intended to replace clinical judgment or establish a protocol for all individuals with this condition, and may not provide the only appropriate approach to diagnosing and managing this problem.

Resistance of Haemophilus influenzae isolates in children under 5 years old with acute respiratory infections in China between 2000 and 2002

This prospective, three-centre study tested for antimicrobial susceptibility in 898 isolates of Haemophilus influenzae between 2000 and 2002 in Chinese children aged under 5 years with acute upper respiratory tract infection. The average incidence of beta-lactamase production was 12.0%. Overall, 88.0% of isolates were susceptible to ampicillin, 100.0% were susceptible to amoxicillin/clavulanic acid, ceftriaxone, cefuroxime and azithromycin, and 99.0% were susceptible to ciprofloxacin. Isolates from Beijing and Shanghai had a lower susceptibility to tetracycline (57.0% and 61.0%, respectively) compared with those from Guangzhou (81.0%), while trimethoprim/sulfamethoxazole susceptibilities in Shanghai (47.0%) and Guangzhou (54.0%) were significantly higher than in Beijing (35.0%). A total of 34.5% of all the isolates were susceptible to all eight of these antimicrobial agents and 12.8% were multi-drug resistant. Ampicillin resistance increased over the duration of the study. These findings show that beta-lactamase production and ampicillin resistance among isolates from Chinese children with upper respiratory tract infection are increasing, and highlight the strong correlation between ampicillin resistance and resistance to cefaclor, chloramphenicol and tetracycline in H. influenzae isolates.

Acute bacterial rhinosinusitis: a review of U.S. treatment guidelines

Acute bacterial rhinosinusitis (ABRS) is a common complication of viral upper respiratory tract infections and is associated with a significant socioeconomic burden. Guidelines for the diagnosis and management of ABRS have been produced in association with a number of societies in the United States; these guidelines aim to promote the rational selection of antibiotic therapy to optimize clinical outcomes while minimizing the potential for selection of antibiotic resistance. This article provides an overview of current U.S. guidelines for the treatment of ABRS, focusing on the impact of antibiotic resistance on treatment options.

In vitro antibacterial activity of beta-lactams and non-beta-lactams against Streptococcus pneumoniae isolates from Sydney, Australia

AIMS

This study was undertaken to determine the antimicrobial resistance patterns of strains of Streptococcus pneumoniae from Sydney, Australia, comparing penicillin-susceptible, -intermediate and -resistant isolates.

METHODS

Non-duplicate cultures of S. pneumoniae were collected from 1 January to 31 December 2002 in the three penicillin-susceptibility categories. Minimum inhibitory concentrations (MICs) of 19 antibacterial agents were determined by agar dilution based on the National Committee for Clinical Laboratory Standards (NCCLS) methodology. Overall for 2002, 687 non-duplicate isolates were obtained, of which 190 (28%) were intermediate or resistant to penicillin. From this set, 183 isolates were selected for study: 88 (48%) in the penicillin-susceptible group (MIC <or= 0.06 mg/L), 25 (14%) in the penicillin-intermediate group (MIC 0.125-1.0 mg/L) and 70 (38%) in the penicillin-resistant group (MIC >or= 2.0 mg/L).

RESULTS

Resistance to non-beta-lactams was more common in penicillin-intermediate or -resistant strains. Multidrug resistance (resistance to >or= 2 non-beta-lactams) was found in 3% of penicillin-susceptible, 52% of penicillin-intermediate and 87% of penicillin-resistant isolates. Erythromycin resistance was seen in 22% of the penicillin-susceptible strains but increased significantly to 60% and 89% in the penicillin-intermediate and resistant strains, respectively. Clindamycin, tetracycline and trimethoprim/sulfamethoxazole showed similar diminished activity in penicillin-intermediate and -resistant strains; 64, 84 and 91% of the penicillin-resistant isolates were resistant to clindamycin, tetracycline and to trimethoprim/sulfamethoxazole, respectively. Chloramphenicol resistance was comparatively low level except 19% of the penicillin-resistant strains were resistant. Ciprofloxacin MICs for 14 strains were raised (MICs 4-16 mg/L); three of these were penicillin-susceptible, one penicillin-intermediate and 10 penicillin-resistant. Only one isolate was resistant to moxifloxacin and to gatifloxacin. Resistance to rifampicin, vancomycin, oritavancin, or linezolid was not detected. Twenty-three isolates were intermediate and one resistant to quinupristin/dalfopristin - 22 of these were penicillin resistant.

CONCLUSIONS

Streptococcus pneumoniae isolates from Sydney are commonly resistant to beta-lactams and available non-beta-lactam agents, especially if they are penicillin non-susceptible. Resistance to moxifloxacin and gatifloxacin is still rare, but some isolates were non-susceptible to quinupristin/dalfopristin. It is important to continue to survey resistance patterns to recognise emerging resistances which affect the selection of empirical antimicrobials to treat infections with S. pneumoniae.

Antimicrobial susceptibility of respiratory tract pathogens in Japan during PROTEKT years 1-3 (1999-2002)

Data are presented on antimicrobial resistance among isolates of Streptococcus pneumoniae, Streptoco-ccus pyogenes, Haemophilus influenzae, and Moraxella catarrhalis collected in Japan during years 1-3 (1999-2002) of the Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin (PROTEKT) surveillance study. In addition to the standard panel of PROTEKT antimicrobial agents, eight other agents often used in Japan also were tested against these isolates. The majority (30%-55%) of S. pneumoniae and H. influenzae isolates were collected from patients with community-acquired pneumonia, whereas most (>70%) S. pyogenes isolates came from patients with tonsillitis/pharyngitis. Penicillin and macrolide resistance were high among isolates of S. pneumoniae, averaging 30.9%-44.5% and 77.2%-79.9%, respectively, across all centers over the 3 study years; the highest occurrences were reported among pediatric patients aged 0-2 years. The erm(B) genotype accounted for >50% of all erythromycin-resistant isolates each study year. S. pyogenes isolates were highly susceptible to most antimicrobial agents except the macrolides and tetracycline. beta-Lactamase production among H. influenzae isolates range was 8.5%-9.7% per annum. A total of 9 beta-lactamase-negative, ampicillin-resistant isolates were collected during the study. Almost all (>95%) M. catarrhalis isolates were beta-lactamase positive each year. Telithromycin was highly active against all pathogens examined in this study during all 3 years.

Demographic analysis of antimicrobial resistance among Streptococcus pneumoniae: worldwide results from PROTEKT 1999–2000

DESIGN

The influence of demographic factors upon antimicrobial resistance among 3362 isolates of Streptococcus pneumoniae from 25 countries was investigated, using univariate comparison and multivariate logistic regression.

RESULTS

Eleven countries had significantly higher rates (Odds ratios [OR]: 2.50-64.79) of penicillin and/or erythromycin resistance than the UK. After taking country effects into account, rates of penicillin resistance (OR 1.98) and erythromycin resistance (OR 1.89) were significantly higher among infants than adults. Fewer (OR 0.69) erythromycin-resistant isolates were collected from male than female patients. There was no difference in the incidence of penicillin or erythromycin resistance among inpatients or outpatients. Penicillin resistance was more prevalent among ear swabs than blood cultures (OR 2.07). Erm(B), the predominant macrolide resistance mechanism across all age groups, was particularly prevalent among bronchoalveolar lavage (69.1%) and sinus (68.8%) isolates. Isolates possessing both erm(B) and mef(A) were generally collected from South Korea and were most common among infants and children (10.3%) and ear samples (17.3%). Telithromycin susceptibility was >99.5%, irrespective of demography.

CONCLUSIONS

Although demography had a significant impact on antimicrobial resistance of pneumococci, telithromycin remained highly active across all demographic groups.

In vitro antibacterial activity of DX-619, a novel des-fluoro(6) quinolone

The in vitro activities of DX-619, des-fluoro(6) quinolone, against 1,208 clinical isolates were examined. DX-619 was particularly potent against staphylococci, including ciprofloxacin- and methicillin-resistant strains; the MIC at which 90% of the strains tested were inhibited was 0.5 microg/ml. In addition, DX-619 was also active against gram-negative bacteria.

Guide to selection of fluoroquinolones in patients with lower respiratory tract infections

Newer fluoroquinolones such as levofloxacin, moxifloxacin, gatifloxacin and gemifloxacin have several attributes that make them excellent choices for the therapy of lower respiratory tract infections. In particular, they have excellent intrinsic activity against Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and the atypical respiratory pathogens. Fluoroquinolones may be used as monotherapy to treat high-risk patients with acute exacerbation of chronic bronchitis, and for patients with community-acquired pneumonia requiring hospitalisation, but not admission to intensive care. Overall, the newer fluoroquinolones often achieve clinical cure rates in > or =90% of these patients. However, rates may be lower in hospital-acquired pneumonia, and this infection should be treated on the basis of anticipated organisms and evaluation of risk factors for specific pathogens such as Pseudomonas aeruginosa. In this setting, an antipseudomonal fluoroquinolone may be used in combination with an antipseudomonalbeta-lactam. Concerns are now being raised about the widespread use, and possibly misuse, of fluoroquinolones and the emergence of resistance among S. pneumoniae, Enterobacteriaceae and P. aeruginosa. A number of pharmacokinetic parameters such as the peak concentration of the antibacterial after a dose (C(max)), and the 24-hour area under the concentration-time curve (AUC24) and their relationship to pharmacodynamic parameters such as the minimum inhibitory and the mutant prevention concentrations (MIC and MPC, respectively) have been proposed to predict the effect of fluoroquinolones on bacterial killing and the emergence of resistance. Higher C(max)/MIC or AUC24/MIC and C(max)/MPC or AUC24/MPC ratios, either as a result of dose administration or the susceptibility of the organism, may lead to a better clinical outcome and decrease the emergence of resistance, respectively. Pharmacokinetic profiles that are optimised to target low-level resistant minor subpopulations of bacteria that often exist in infections may help preserve fluoroquinolones as a class. To this end, optimising the AUC24/MPC or C(max)/MPC ratios is important, particularly against S. pneumoniae, in the setting of lower respiratory tract infections. Agents such as moxifloxacin and gemifloxacin with high ratios against this organism are preferred, and agents such as ciprofloxacin with low ratios should be avoided. For agents such as levofloxacin and gatifloxacin, with intermediate ratios against S. pneumoniae, it may be worthwhile considering alternative dose administration strategies, such as using higher dosages, to eradicate low-level resistant variants. This must, of course, be balanced against the potential of toxicity. Innovative approaches to the use of fluoroquinolones are worth testing in further in vitro experiments as well as in clinical trials.

Appropriate Outpatient Macrolide Use in Community‐Acquired Pneumonia

PURPOSE

To review current guidelines concerning the outpatient management of community-acquired pneumonia (CAP), to discuss antibiotic resistance and its relation to outcomes, and to define the appropriate use of newer macrolides in CAP.

DATA SOURCES

Comprehensive review of the scientific literature, comparison of published clinical practice guidelines, and expert opinion.

CONCLUSIONS

Despite increasing knowledge regarding its etiology and pathogenesis, CAP remains the seventh leading cause of death in the United States. Although 80% of all patients with CAP are treated as outpatients, over 1 million hospital admissions due to CAP occur each year. From an employer perspective, total annual employer costs were fivefold greater for patients with pneumonia than for those who were not affected. Appropriate antimicrobial choices should lead to improved outcomes. Reports of increasing resistance of pathogens associated with CAP, increasing frequency of atypical pathogens, and the availability of an increasing number of antimicrobials have made treatment decisions more involved.

IMPLICATIONS FOR PRACTICE

In an effort to improve outcomes, several guidelines have been published recommending appropriate antimicrobial agents to treat CAP in different patient populations. All guidelines base treatment recommendations on the hospitalization status of the patient, and all agree that coverage of atypical pathogens as part of an initial empirical regimen is important. Comorbidity and modifying factors that may increase the risk of infection with resistant organisms also are taken into account. Controversy exists regarding the use of newer macrolides versus newer fluoroquinolones as initial empirical therapy. The applicability of the reported increasing resistance of common pneumonia pathogens to outcomes in regimens containing newer macrolides is a subject of debate. Defining appropriate antimicrobial use in different patient groups should help achieve better outcomes and allay the development of resistance.

High nasopharyngeal carriage of drug resistant Streptococcus pneumoniae and Haemophilus influenzae in North Indian schoolchildren

OBJECTIVES

To determine the carriage rate of Streptococcus pneumoniae and Haemophilus influenzae in healthy Indian schoolchildren. The prevalence of antibiotic resistant strains in the community may be used to assess the trends of antibiotic resistance in invasive strains. Prevalence of resistance to various antimicrobial drugs among S. pneumoniae and H. influenzae was estimated.

METHODS

Two thousand four hundred subjects, aged 5-10 years, were enrolled from 45 rural and 45 urban schools. A nasopharyngeal swab was collected from each child, after taking informed written consent. Swabs were processed to isolate S. pneumoniae and H. influenzae. All isolates were tested for resistance to chloramphenicol, erythromycin and co-trimoxazole. Streptococcus pneumoniae isolates were also tested against tetracycline and oxacillin while H. influenzae isolates were tested against ampicillin.

RESULTS

Nasopharyngeal carriage of S. pneumoniae and H. influenzae was high in healthy schoolchildren. Stratified analysis showed that nasal carriage of pneumococci in urban children was significantly lower than in rural children [46.8% vs. 53.2%, P<0.001]. Carriage rates of H. influenzae in male and female populations were significantly different (47.8% vs. 52.3%, P<0.04). Penicillin resistance in S. pneumoniae was found low (3.3%), but 22.9% of H. influenzae isolates were ampicillin resistant. Resistance to co-trimoxazole was very high in both S. pneumoniae (81.8%) and H. influenzae (67.3%).

CONCLUSION

There is high nasopharyngeal carriage of drug resistant S. pneumoniae and H. influenzae in schoolchildren of north India. Currently, in India, co-trimoxazole for 5 days is recommended for treatment of non-severe pneumonia and third generation cephalosporins are drug of choice for management of severe pneumococcal/H. influenzae diseases. We found high co-trimoxazole resistance and low penicillin resistance in pneumococcal isolates. This justifies empirical use of penicillin in management of invasive pneumococcal infections in India.

Role of beta-lactam agents in the treatment of community-acquired pneumonia

Community-acquired pneumonia (CAP) is a common illness associated with high rates of morbidity and mortality worldwide. The beta-lactam antibacterial agents have been the mainstay of therapy for CAP for over four decades and remain as first-line therapy. However, the impact of the substantial prevalence of resistance seen among the common respiratory pathogens, particularly penicillin and macrolide resistance among Streptococcus pneumoniae, is now an area for concern. CAP treatment guidelines often recommend the use of a macrolide or fluoroquinolone in conjunction with, or as an alternative to, beta-lactam agents, but whether this is necessary is uncertain. This review outlines the historical use of beta-lactam antibacterial agents in the treatment of CAP along with their ongoing therapeutic utility.

Update on treatment guidelines for acute bacterial sinusitis

Acute bacterial sinusitis (ABS) is a common complication of viral upper respiratory tract infections and represents a considerable social burden both in terms of diminished quality of life for the patient and the economic implications of decreased productivity and treatment costs. Several national health authorities have developed guidelines for the management of ABS, which aim to promote rational selection of anti-bacterial therapy to optimise clinical outcomes while minimising the potential for selection of anti-bacterial resistance as a result of inappropriate anti-bacterial usage. This article provides an overview of current guidelines, with particular focus on the clinical significance of variations in treatment recommendations and new treatment options, such as the ketolide telithromycin, which was recently added to a number of national treatment guidelines.

PROTEKT 1999–2000: a multicentre study of the antimicrobial susceptibility of respiratory tract pathogens in Japan

DESIGN

A six-centre study in Japan during the winter of 1999-2000 assessed the in vitro activity of >20 antimicrobial agents against the common respiratory pathogens Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, and Moraxella catarrhalis. The minimum inhibitory concentrations (MIC) of each antimicrobial was determined against these isolates using National Committee for Clinical Laboratory Standards (NCCLS) methodology.

RESULTS

Among S. pneumoniae isolates, 44.5% were penicillin resistant. The macrolide resistance rate was 77.9% with 90.5% of penicillin-resistant strains also being macrolide resistant. Resistance mechanisms in macrolide-resistant isolates were identified as mef(A) or erm(B) in 42.5% and 52.5%, respectively. Of the fluoroquinolone-resistant isolates (1.3%), most were also penicillin and macrolide resistant. All strains were inhibited by telithromycin at <or=1mg/L. Among S. pyogenes isolates, erythromycin resistance was 17.5% overall but showed considerable variation among the six centres. For H. influenzae, 8.5% produced beta-lactamase and a single beta-lactamase-negative, ampicillin-resistant isolate (0.36%) was obtained, and there was no fluoroquinolone resistance. All isolates were susceptible to telithromycin. Most antimicrobials showed good activity against M. catarrhalis, although 96.7% were beta-lactamase positive.

CONCLUSION

The prevalence of antimicrobial resistance to macrolides, penicillin and the fluoroquinolones among the common respiratory pathogens is high in Japan.

Global distribution of Streptococcus pneumoniae serotypes isolated from paediatric patients during 1999–2000 and the in vitro efficacy of telithromycin and comparators

Few data exist on the distribution of Streptococcus pneumoniae serotypes in many countries and in non-invasive disease overall. Here, data are presented from 772 paediatric isolates from children with community-acquired respiratory tract infections isolated from the PROTEKT global surveillance study during 1999–2000. Overall, 60.0 % of isolates were covered by the 7-valent pneumococcal vaccine formulation (PCV7), with greater coverage in the USA compared with Europe (69.6 vs 55.5 %, P = 0.014). Geographically dispersed clones of serogroups 3, 11 and 15 accounted for most of the isolates outside PCV7 coverage. Overall, macrolide, penicillin and cotrimoxazole non-susceptibility rates were high; however, all isolates were susceptible to telithromycin. Although only 7.4 % of isolates were resistant to amoxycillin/clavulanate, a higher prevalence of resistance was found in isolates from the USA and South Korea. This study shows the feasibility and importance of serotyping antibiotic surveillance study isolates and the potential of telithromycin as an important option for empiric therapy.

A review of clinical failures associated with macrolide-resistant Streptococcus pneumoniae

The emerging reports of clinical failures using macrolides and their associations with macrolide-resistant Streptococcus pneumoniae prompted us to review the literature describing these cases. Thirty-three cases reporting macrolide treatment failure during treatment of pneumococcal infections were available for review. The most prevalent diagnosis (24/27 or 88.8% of available diagnoses) was community-acquired pneumonia (CAP). Previous medical history included cardiopulmonary disease in eight (24.2%) and immunocompromised states in five (15.1%) patients. The majority, 31/33 (93.9%) of patients received oral macrolide treatment in an outpatient setting. S. pneumoniae was isolated from the blood in 26 (78.8%) of 33 patients, three (9.1%) patients had bacteria present in both blood and cerebrospinal fluid, two (6%) patients grew S. pneumoniae from blood and bronchial washings and two (6%) patients had positive sputum cultures. The MLS(B) phenotype was the most predominant phenotype present in 12 (63.2%) of 19 patients. After failing initial macrolide treatment, 26 (78.8%) of 33 patients received parenteral antibiotic treatment. Of 33 patients admitted to hospital, 29 (87.8%) had their outcome described as 'survived'.

Antibacterial susceptibility testing in the clinical laboratory

This article familiarizes the clinician with the principles of bacterial susceptibility testing and reporting to facilitate communication with the clinical microbiology laboratory. The emergence of resistance in nearly all commonly isolated bacterial organisms has highlighted the need for ongoing dialogue between the laboratory and those who use its services.

Activity of telithromycin and comparators against bacterial pathogens isolated from 1,336 patients with clinically diagnosed acute sinusitis

Background

Increasing antimicrobial resistance among the key pathogens responsible for community-acquired respiratory tract infections has the potential to limit the effectiveness of antibiotics available to treat these infections. Since there are regional differences in the susceptibility patterns observed and treatment is frequently empirical, the selection of antibiotic therapy may be challenging. PROTEKT, a global, longitudinal multicentre surveillance study, tracks the activity of telithromycin and comparator antibacterial agents against key respiratory tract pathogens.

Methods

In this analysis, we examine the prevalence of antibacterial resistance in 1,336 bacterial pathogens, isolated from adult and paediatric patients clinically diagnosed with acute bacterial sinusitis (ABS).

Results and discussion

In total, 58.0%, 66.1%, and 55.8% of S. pneumoniae isolates were susceptible to penicillin, cefuroxime, and clarithromycin respectively. Combined macrolide resistance and reduced susceptibility to penicillin was present in 200/640 (31.3 %) of S. pneumoniae isolates (128 isolates were resistant to penicillin [MIC >= 2 mg/L], 72 intermediate [MIC 0.12–1 mg/L]) while 99.5% and 95.5% of isolates were susceptible to telithromycin and amoxicillin-clavulanate, respectively. In total, 88.2%, 87.5%, 99.4%, 100%, and 100% of H. influenzae isolates were susceptible to ampicillin, clarithromycin, cefuroxime, telithromycin, and amoxicillin-clavulanate, respectively. In vitro, telithromycin demonstrated the highest activity against M. catarrhalis (MIC₅₀ = 0.06 mg/L, MIC₉₀ = 0.12 mg/L).

Conclusion

The high in vitro activity of against pathogens commonly isolated in ABS, together with a once daily dosing regimen and clinical efficacy with 5-day course of therapy, suggest that telithromycin may play a role in the empiric treatment of ABS.

Streptococcus pneumoniae and community-acquired pneumonia: a cause for concern

Community-acquired pneumonia (CAP) is the sixth most common cause of death in the United States and the leading cause of death from infectious diseases. It is associated with significant morbidity and mortality, and poses a major economic burden to the healthcare system. Streptococcus pneumoniae is the leading cause of CAP. Other common bacterial causes include Haemophilus influenzae as well as atypical bacteria (Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species). Increasing resistance to a variety of antimicrobial agents has been documented in S. pneumoniae and is common in H. influenzae as well. Successful empiric therapy is paramount to the management of CAP to avoid treatment failure and subsequent associated costs. Given that resistance is increasing among respiratory pathogens, and S. pneumoniae is the most common etiologic agent identified in CAP, strategies for antimicrobial therapy should be based on the likely causative pathogen, the presence of risk factors for infection with resistant bacteria, and local resistance patterns.

Antimicrobial susceptibility of respiratory Haemophilus influenzae strains isolated from pediatric respiratory tract infections

BACKGROUND

Haemophilus influenzae (H. influenzae) is the most frequent bacterial pathogen of respiratory tract infections in children. Detection of antimicrobial susceptibility of H. influenzae is necessary for institution of appropriate antibiotic treatments.

METHODS

A total of 281 strains of H. influenzae isolated from sputum samples of 281 pediatric patients with respiratory tract infections were recruited for study. Antibiotic susceptibility was determined by assessing minimum inhibitory concentrations (MIC) of antimicrobial agents. MIC were measured by utility of Agar dilution susceptibility test.

RESULTS

Of the total, 38 (13.5%) strains produced beta-lactamase (BLP), 56 (19.9%) strains were beta-lactamase non-producing, ampicillin resistant (BLNAR). The overall resistant proportion to ampicillin was 33.4%. The data indicated that sulbactam/ampicillin, cefotaxime, ceftriaxone and cefditoren are effective against BLP strains. In addition, a high prevalence of BLNAR H. influenzae strains was identified, with an overall isolation rate of 19.9%. Those strains mainly demonstrated intermediate level to ampicillin (ampicillin-MIC </= 3.13 micro g/mL for most of BLNAR strains). However, antimicrobial activities of cefotaxime, ceftriaxone and cefditoren against those strains were slightly diminished. Recovery rate of BLP strains was varied by years, peaking at 19.5%. In particular, a trend of yearly increase in frequency of BLNAR strains was observed.

CONCLUSION

Frequency of BLNAR strains causing respiratory infections has been dramatically increasing, which can diminish antibiotic activities of not only ampicillin but also of some cephems.

Clarithromycin in 2003: sustained efficacy and safety in an era of rising antibiotic resistance

Data from surveillance studies show increasing prevalence of respiratory pathogens resistant to commonly used antibiotics. Thus, a Medline search was conducted to identify studies of clarithromycin, especially those addressing macrolide resistance. Changing trends of in vitro susceptibility have not affected clinical efficacy with clarithromycin. Over the last 12 years, clarithromycin study results have shown consistent rates of clinical cure and bacteriological eradication, which are similar to those observed with comparator agents. The incidence of clarithromycin treatment failure in patients infected with Streptococcus pneumoniae is substantially less than that predicted by macrolide resistance rates from surveillance programmes. In summary, despite widespread use since its introduction, clarithromycin remains active both in vitro and in vivo against clinically relevant respiratory tract pathogens.

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.

Antibiotic selection pressure and resistance in Streptococcus pneumoniae and Streptococcus pyogenes

We correlated outpatient antibiotic use with prevalence of penicillin-nonsusceptible Streptococcus pneumoniae (PNSP), macrolide-resistant S. pneumoniae (MRSP), and macrolide-resistant S. pyogenes (MRGAS) in 20 countries. Total antibiotic use was correlated with PNSP (r = 0.75; p < 0.001), as was macrolide use with MRSP (r = 0.88; p < 0.001) and MRGAS (r = 0.71; p = 0.004). Streptococcal resistance is directly associated with antibiotic selection pressure on a national level.

Molecular epidemiology of multiresistant Streptococcus pneumoniae with both erm(B)- and mef(A)-mediated macrolide resistance

Of a total of 1043 macrolide-resistant Streptococcus pneumoniae isolates collected from 24 countries as part of PROTEKT 1999-2000, 71 isolates tested positive for both the mef(A) and erm(B) genes. Of 69 isolates subjected to further molecular investigations, all were resistant to tetracycline, 63 (91.3%) were resistant to penicillin, and 57 (82.6%) were resistant to trimethoprim-sulfamethoxazole. One isolate was also fluoroquinolone resistant, and another was resistant to quinupristin-dalfopristin. The ketolide telithromycin retained activity against all of the isolates. Of the 69 of these 71 isolates viable for further testing, 46 were from South Korea, 13 were from the United States, 8 came from Japan, and 1 each came from Mexico and Hungary. One major clonal complex (59 [85.5%] of 69 isolates) was identified by serotyping (with 85.5% of the isolates being 19A or 19F), pulsed-field gel electrophoresis, and multilocus sequence typing. The remaining isolates were less clonal in nature. Representative isolates were shown to carry the mobile genetic elements Tn1545 and mega, were negative for Tn1207.1, had tetracycline resistance mediated by tet(M), and contained the mef(E) variant of mef(A). All isolates were positive for mel, a homologue of the msr(A) efflux gene. These clones are obviously very efficient at global dissemination, and hence it will be very important to monitor their progress through continued surveillance. Telithromycin demonstrated high levels of activity (MIC for 90% of the strains tested, 0.5 micro g/ml; MIC range, 0.06 to 1 micro g/ml) against all isolates.

In vitro and in vivo antibacterial activities of DK-507k, a novel fluoroquinolone

The antibacterial activities of DK-507k, a novel quinolone, were compared with those of other quinolones: ciprofloxacin, gatifloxacin, levofloxacin, moxifloxacin, sitafloxacin, and garenoxacin (BMS284756). DK-507k was as active as sitafloxacin and was as active as or up to eightfold more active than gatifloxacin, moxifloxacin, and garenoxacin against Streptococcus pneumoniae, methicillin-susceptible and methicillin-resistant Staphylococcus aureus, and coagulase-negative staphylococci. DK-507k was as active as or 4-fold more active than garenoxacin and 2- to 16-fold more active than gatifloxacin and moxifloxacin against ciprofloxacin-resistant strains of S. pneumoniae, including clinical isolates and in vitro-selected mutants with known mutations. DK-507k inhibited all ciprofloxacin-resistant strains of S. pneumoniae at 1 microg/ml. A time-kill assay with S. pneumoniae showed that DK-507k was more bactericidal than gatifloxacin and moxifloxacin. The activities of DK-507k against most members of the family Enterobacteriaceae were comparable to those of ciprofloxacin and equal to or up to 32-fold higher than those of gatifloxacin, levofloxacin, moxifloxacin, and garenoxacin. DK-507k was fourfold less active than sitafloxacin and ciprofloxacin against Pseudomonas aeruginosa, while it was two to four times more potent than levofloxacin, gatifloxacin, moxifloxacin, and garenoxacin against P. aeruginosa. In vivo, intravenous treatment with DK-507k was more effective than that with gatifloxacin and moxifloxacin against systemic infections caused by S. aureus, S. pneumoniae, and P. aeruginosa in mice. In a mouse model of pneumonia due to penicillin-resistant S. pneumoniae, DK-507k administered subcutaneously showed dose-dependent efficacy and eliminated the bacteria from the lungs, whereas gatifloxacin and moxifloxacin had no significant efficacy. Oral treatment with DK-507k was slightly more effective than that with ciprofloxacin in a rat model of foreign body-associated urinary tract infection caused by a P. aeruginosa isolate for which the MIC of DK-507k was fourfold higher than that of ciprofloxacin. Oral administration of DK-507k to rats achieved higher peak concentrations in serum and higher concentrations in cumulative urine than those achieved with ciprofloxacin. These data indicate the potential advantages of DK-507k over other quinolones for the treatment of a wide range of community-acquired infections.

The activity of levofloxacin and other antimicrobials against clinical isolates of Streptococcus pneumoniae collected worldwide during 1999-2002

Streptococcus pneumoniae is the most important causative bacterial pathogen in respiratory infections. Globally, increasing levels of resistant strains highlight the need for continued surveillance programs to guide antibiotic choice. The current study compared susceptibility results of 4,788 strains of S. pneumoniae collected during 2001-2002 to susceptibility results from 3,884 strains collected from the same hospitals during 1999-2000. Participant centers were dispersed throughout five regions. By region, the prevalence of penicillin-resistant S. pneumoniae and percentage change from the previous 1999-2000 study was Mexico (26.0%, 12.5%), Brazil (7.9%; 5.5%), Asia (China, Hong Kong, South Korea, Thailand) (44.1%; 0.8%), Europe (France, Germany, Italy, Spain, UK) (11.1%; -0.6%) and South Africa (7.9; -1.8%). Multidrug-resistant (MDR) strains of S. pneumoniae were most frequently isolated from Asia (36.3%) compared with approximately 5% in the other four regions. Increases in the incidence of MDR isolates in Mexico (13.5%), Brazil (1.7%) and Asia (6.1%) were reported with no increases in MDR in South Africa and Europe. Levofloxacin resistance was rarely associated with MDR phenotypes. Levofloxacin maintained an MIC(90) of 1 microg/ml against the isolates collected from all five regions with no change during the study periods, despite differences in levofloxacin resistance rates between regions or nations (0%-3.2%). The prevalence of levofloxacin resistance (MIC > or =8 microg/ml) increased only slightly over the study period in Europe (0.3%-0.7%) and in Asia (3.0-3.2%), but little or no change was seen in Mexico (3.8%-0%) or Brazil or South Africa, where no levofloxacin resistant isolates were detected in either study period.

Fluoroquinolone AUIC break points and the link to bacterial killing rates. Part 1: In vitro and animal models

OBJECTIVE

To review in vitro and animal model studies with fluoroquinolones and the pharmacokinetic and pharmacodynamic relationships that are predictive of clinical and microbiologic outcomes and resistance. Data on fluoroquinolones are summarized and examine the premise that a single area under the inhibitory concentration-time curve (AUIC) target >125 may be used for all fluoroquinolones with concentration-dependent killing actions and against all target organisms.

DATA SOURCES

Primary articles were identified by MEDLINE search (1966-February 2002) and through secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All of the articles identified from the data sources were evaluated, and all information deemed relevant was included.

DATA SYNTHESIS

The fluoroquinolones exhibit concentration-dependent killing. This effect clearly depends on concentrations achieved, and outcomes depend on endpoints established by individual investigators. With AUIC values <60, the actions of fluoroquinolones are essentially bacteriostatic; any observed bacterial killing is the combined effect of low concentrations in relation to minimum inhibitory concentration and the action of host factors such as neutrophils and macrophages. AUIC values >100 but <250 yield bacterial killing at a slow rate, but usually by day 7 of treatment. AUICs >250 produce rapid killing, and bacterial eradication occurs within 24 hours. Disagreements regarding target endpoints are the expected consequences of comparing microbial and clinical outcomes across animal models, in vitro experiments, and humans when the endpoints are clearly not equivalent. Careful attention to time-related events, such as speed of bacterial killing, versus global endpoints, such as bacteriologic cure, allows optimal break points to be defined.

CONCLUSIONS

Evidence from in vitro and animal models favors the use of AUIC values >250 for rapid bactericidal action, regardless of whether the organism is gram-negative or gram-positive.

Macrolide resistance: an increasing concern for treatment failure in children

BACKGROUND

Antimicrobial treatment of pediatric respiratory tract infections has evolved during the past 30 years as a result of antimicrobial resistance. The focus of antimicrobial therapy in these conditions has shifted from penicillins to other agents because of the dramatic increase in antimicrobial resistance among common respiratory pathogens, including Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. It is important for clinicians to understand how resistance develops so that they can help prevent this phenomenon from occurring with other antimicrobials.

METHODS

This article reviews the published literature on resistance to macrolide antimicrobials among common pediatric respiratory tract pathogens and clinical and bacteriologic outcomes of infections with these pathogens.

RESULTS

Resistance among common pediatric respiratory tract pathogens to macrolides occurs through two main mechanisms, alteration of the target site and active efflux. Although resistance patterns vary by geographic region, the widespread use of macrolides has contributed to the emergence of both types of macrolide-resistant organisms. Conditions that favor the selection and proliferation of resistant strains include children with repeated, close contact who frequently receive antimicrobial treatment or prophylaxis, such as children who attend day care. Recent US surveillance data show that 20 to 30% of S. pneumoniae are resistant to macrolides, with approximately two-thirds of macrolide-resistant strains associated with an efflux mechanism and the remainder associated with a ribosomal methylase. Additionally, although less well-known, virtually all strains of H. influenzae have an intrinsic macrolide efflux pump. As resistance to macrolides has increased, clinical failures have resulted, and these agents are no longer considered appropriate for empiric first line antimicrobial therapy of acute otitis media and sinusitis unless patients are truly penicillin-allergic. Therefore, other antimicrobials are recommended for the empiric treatment of children with respiratory tract infections, including higher doses of amoxicillin and amoxicillin/clavulanate (90 mg/kg/day amoxicillin), cefuroxime axetil and intramuscular ceftriaxone.

CONCLUSIONS

As resistance to macrolides increases and clinical failures in children become more common with this class of antimicrobials, judicious use of antimicrobials is needed. This includes limiting antimicrobial use for viral infections and using the most effective agents when antimicrobials are clinically indicated, such as higher doses of amoxicillin and amoxicillin/clavulanate. Application of these principles may prevent proliferation and further development of resistance.