Macrolide resistance among invasive Streptococcus pneumoniae isolates

Bacteriological efficacy of 5-day therapy with telithromycin in acute maxillary sinusitis

Increasing resistance among the key pathogens responsible for community-acquired respiratory tract infections, namely Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis, has the potential to limit the effectiveness of the antibacterial agents available to treat these infections. Moreover, there are regional differences in the susceptibility patterns observed and, as treatment is usually empirical, choosing an effective treatment can be challenging. Telithromycin, the first ketolide to be approved for clinical use, offers an activity profile that covers the key respiratory pathogens including penicillin- and macrolide-resistant S. pneumoniae as well as beta-lactamase-producing H. influenzae and M. catarrhalis. In a pooled analysis of three large controlled clinical trials involving patients with acute maxillary sinusitis, the bacteriological efficacy of 5- or 10-day treatment with telithromycin and 10-day treatment with comparators was evaluated. Telithromycin administered as a once-daily 800 mg dose for 5 days achieved eradication rates of 91.8, 87.5 and 92.9% for S. pneumoniae, H. influenzae and M. catarrhalis, respectively. Bacteriological eradication of 8/10 and 12/14 isolates of S. pneumoniae resistant to penicillin and erythromycin, respectively, was also reported following 5-day treatment with telithromycin. The clinical efficacy of this regimen was equivalent to that of a 10-day regimen of telithromycin or standard 10-day courses of amoxicillin-clavulanic acid or cefuroxime axetil. Telithromycin 800mg given for 5 days was well tolerated, with the majority of adverse events being of mild or moderate intensity. These data suggest that telithromycin provides effective first-line therapy for use in patients with acute maxillary sinusitis in a short and convenient once-daily dosage regimen.

In-vitro susceptibility and molecular characterisation of macrolide resistance mechanisms among Streptococcus pneumonia isolates in The Netherlands: the DUEL 2 study

In total, 881 presumptive clinical isolates of Streptococcus pneumoniae collected from throughout The Netherlands were analysed to determine their mechanisms of macrolide resistance. Isolates were identified initially by participating laboratories using their own standard identification technique, followed by determination of MICs with Etests. Only 797 isolates were confirmed as pneumococci following bile-solubility tests, lytA PCR and 16S rRNA sequencing. Of these confirmed pneumococci, 59 (7.4%) isolates were macrolide-resistant. Analysis by PCR indicated that 34 (57.6%) isolates harboured only the erm(B) gene and 16 (27.1%) only the mef gene. Three (5.1%) isolates carried both erm(B) and mef, while six (10.2%) isolates were negative for both mechanisms. Of the six negative isolates, three had a mutation in the 23S rRNA gene, and three were negative for all mechanisms tested. No isolates with the erm(A) subclass erm(TR) gene were detected. Among the 19 mef-positive isolates, 14 (73.7%) carried the mef(A) gene, and only five (26.3%) carried the mef(E) gene. No linezolid cross-resistance or multiresistance (resistance to more than two classes of antibiotics) was observed.

Time-kill study of the activity of telithromycin against macrolide-resistant Streptococcus pneumoniae Isolates with 23S rRNA mutations and changes in ribosomal proteins L4 and L22

By use of a time-kill methodology, the antipneumococcal activity of telithromycin was determined against macrolide-resistant S. pneumoniae isolates having mutations in the 23S rRNA gene and changes in the ribosomal proteins L4 and L22. Telithromycin had MICs ranging between 0.03 and 0.25 microg/ml and was bactericidal against four of seven strains after 24 h at two times the MIC.

Predominance of 23S rRNA mutants among non-erm, non-mef macrolide-resistant clinical isolates of Streptococcus pneumoniae collected in the United States in 1999-2000

A total of 322 erythromycin-resistant pneumococci from TRUST 3 and TRUST 4 United States surveillance studies (1999-2000) were screened for 23S rRNA, L4, and L22 gene mutations. Nineteen isolates, two with mefA, had mutations at position 2058 or 2059 in 23S rRNA. Two had a 69GTG71-to-TPS substitution in L4; one of these also contained ermA.

Efficacy of Telithromycin in Community-Acquired Pneumonia Caused by Pneumococci with Reduced Susceptibility to Penicillin and/or Erythromycin

BACKGROUND

The efficacy of oral telithromycin was assessed in patients with community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae with reduced susceptibility to penicillin and/or erythromycin.

METHODS

Patients with CAP who had received telithromycin 800 mg once daily for 5 or 7-10 days (n = 2,289) in eight phase III clinical trials, or telithromycin 800 mg once daily for 7 days (n = 50) in a phase II study were included in this pooled analysis. Patients with S. pneumoniae as the cause of infection were identified, with particular focus on those infected with strains with reduced susceptibility to penicillin (intermediate, minimal inhibitory concentration (MIC) 0.12-1.0 mg/l; resistant, MIC >or=2.0 mg/l) and/or resistance to erythromycin (MIC >or=1.0 mg/l). Per-protocol clinical and bacteriological outcomes were assessed 7-14 days post-therapy in the phase III studies, and at 7-21 days post-therapy or at the end of therapy in the phase II study.

RESULTS

Of the 327 telithromycin-treated patients with S. pneumoniae infection, 61 (19%) were infected with strains with reduced susceptibility to penicillin and/or erythromycin. Clinical cure and bacterial eradication rates in these patients were 91.8% (56/61) and 93.4% (57/61), respectively. Corresponding clinical cure and bacterial eradication rates overall for all isolates of pneumococci were 94.5% (309/327) and 96.0% (314/327), respectively. All isolates with reduced susceptibility to penicillin and/or erythromycin were susceptible to telithromycin (MIC <or=1.0 mg/l).

CONCLUSION

These results indicate that telithromycin is an effective oral antibacterial for the treatment of CAP caused by pneumococci with reduced susceptibility to penicillin and/or erythromycin.

Erythromycin-nonsusceptible Streptococcus pneumoniae in children, 1999-2001

After increasing from 1995 to 1999, invasive erythromycin-nonsusceptible Streptococcus pneumoniae rates per 100,000 decreased 53.6% in children from Baltimore, Maryland (US), from 1999 to 2001, which was partially attributed to strains related to the mefE-carrying England¹⁴-9 clone. The decline in infection rates was likely due to the pneumococcal 7-valent conjugate vaccine.

A nationwide survey of physician office visits found that inappropriate antibiotic prescriptions were issued for bacterial respiratory tract infections in ambulatory patients

OBJECTIVE

Correlations between probabilities of resistance and the frequencies with which antibiotics were prescribed for treating bacterial respiratory infections were examined in a nationwide ambulatory population.

STUDY DESIGN AND SETTING

The data of a nationwide probability sample survey of visits to physician offices in the United States in 1999 were used to conduct this study of drug use. A clinical pharmacologist identified antibiotics prescribed during those visits using a large online database. The participating physicians diagnosed the bacterial respiratory infections. An infectious disease expert determined the probabilities of bacterial resistance from a nationwide antibiotic surveillance database.

RESULTS

Various bacterial respiratory infections were diagnosed during 6.5% of physician office visits in 1999. One or more antibiotics were prescribed during 51.0% of those visits. The probabilities of resistance to the most frequently prescribed antibiotics varied from 20% to 40% and showed a weak positive correlation with the frequencies of antibiotic prescriptions.

CONCLUSION

A significant number of inappropriate antibiotic prescriptions were issued for infections with a high probability of bacterial resistance to the prescribed antibiotics.

Resistance to macrolide, lincosamide, streptogramin, ketolide, and oxazolidinone antibiotics

Macrolides have enjoyed a resurgence as new derivatives and related compounds have come to market. These newer compounds have become important in the treatment of community-acquired pneumoniae and nontuberculosis-Mycobacterium diseases. In this review, the bacterial mechanisms of resistance to the macrolide, lincosamide, streptogramin, ketolide, and oxazolidinone antibiotics, the distribution of the various acquired genes that confer resistance, as well as mutations that have been identified in clinical and laboratory strains are examined.

The "minimizing antibiotic resistance in Colorado" project: impact of patient education in improving antibiotic use in private office practices

OBJECTIVE

To assess the marginal impact of patient education on antibiotic prescribing to children with pharyngitis and adults with acute bronchitis in private office practices.

DATA SOURCES/STUDY SETTING

Antibiotic prescription rates based on claims data from four managed care organizations in Colorado during baseline (winter 2000) and study (winter 2001) periods.

STUDY DESIGN

A nonrandomized controlled trial of a household and office-based patient educational intervention was performed. During both periods, Colorado physicians were mailed antibiotic prescribing profiles and practices guidelines as part of an ongoing quality improvement program. Intervention practices (n=7) were compared with local and distant control practices.

DATA COLLECTION/EXTRACTION METHODS

Office visits were extracted by managed care organizations using International Classification of Diseases-9-Clinical Modification codes for acute respiratory tract infections, and merged with pharmacy claims data based on visit and dispensing dates coinciding within 2 days.

PRINCIPAL FINDINGS

Adjusted antibiotic prescription rates during baseline and study periods increased from 38 to 39 percent for pediatric pharyngitis at the distant control practices, and decreased from 39 to 37 percent at the local control practices, and from 34 to 30 percent at the intervention practices (p=.18 compared with distant control practices). Adjusted antibiotic prescription rates decreased from 50 to 44 percent for adult bronchitis at the distant control practices, from 55 to 45 percent at the local control practices, and from 60 to 36 percent at the intervention practices (p<.002 and p=.006 compared with distant and local control practices, respectively).

CONCLUSIONS

In office practices, there appears to be little room for improvement in antibiotic prescription rates for children with pharyngitis. In contrast, patient education helps reduce antibiotic use for adults with acute bronchitis beyond that achieved by physician-directed efforts.

Incidence of macrolide resistance in Streptococcus pneumoniae after introduction of the pneumococcal conjugate vaccine: population-based assessment

BACKGROUND

The prevalence of macrolide resistance in Streptococcus pneumoniae has risen in recent years after the introduction of new macrolides and their increased use. We assessed emergence of macrolide-resistant invasive S pneumoniae disease in Atlanta, GA, USA, before and after the licensing, in February 2000, of the heptavalent pneumococcal conjugate vaccine for young children.

METHODS

Prospective population-based surveillance was used to obtain pneumococcal isolates and demographic data from patients with invasive pneumococcal disease. We calculated cumulative incidence rates for invasive pneumococcal disease for 1994-2002 using population estimates and census data from the US Census Bureau.

FINDINGS

The incidence of invasive pneumococcal disease in Atlanta fell from 30.2 per 100,000 population (mean annual incidence 1994-99) to 13.1 per 100,000 in 2002 (p<0.0001). Striking reductions were seen in children younger than 2 years (82% decrease) and in those 2-4 years (71% decrease), age-groups targeted to receive pneumococcal conjugate vaccine. Significant declines were also noted in adults aged 20-39 (54%), 40-64 (25%), and 65 years and older (39%). Macrolide resistance in invasive S pneumoniae disease in Atlanta, after increasing steadily from 4.5 per 100,000 in 1994 to 9.3 per 100,000 in 1999, fell to 2.9 per 100,000 by 2002. Reductions in disease caused by mefE-mediated and erm-mediated macrolide-resistant isolates of conjugate-vaccine serotypes 6B, 9V, 19F, and 23F, and the vaccine-associated serotype 6A were also recorded.

INTERPRETATION

Vaccines can be a powerful strategy for reducing antibiotic resistance in a community.

Provider and practice characteristics associated with antibiotic use in children with presumed viral respiratory tract infections

OBJECTIVE

Although overuse of antibiotics in children has been well documented, relatively little information is known about provider and facility characteristics associated with this prescribing practice. This study was done to evaluate the differences in overuse of antibiotics among staff physicians and resident/interns (housestaff [HS]) who work in hospital-based outpatient clinics.

METHODS

This cross-sectional study involved patient encounters in outpatient departments that were included in the US National Hospital Ambulatory Medical Care Survey database from 1995 to 2000. Encounters with patients who were aged <18 years and had a primary diagnosis suggestive of viral respiratory tract infection were evaluated. Patients with comorbid conditions that might justify antibiotic use were excluded.

RESULTS

This study included 1952 patient encounters with a primary diagnosis suggestive of a viral infection and 33.2% of these patients receiving antibiotics. Overall, antibiotic use was significantly less among HS (19.5%) than staff physicians (36.4%; odds ratio [OR]: 0.44; 95% confidence interval [CI]: 0.33-0.59). This difference between HS (19.5%) and staff physicians (32.5%) persisted even within teaching hospitals (OR: 0.5; 95% CI: 0.4-0.7). Among staff physicians, antibiotic use was greater among those who work in nonteaching (39.6%) compared with teaching hospitals (32.5%; OR: 1.51; 95%: CI 1.15-1.98). Controlling for other patient and provider variables, antibiotic use occurred less among HS than among staff physicians in teaching hospitals (OR: 0.53; 95% CI: 0.38-0.75).

CONCLUSIONS

Antibiotic prescribing in the context of an outpatient visit for a diagnosis suggestive of a viral respiratory tract illness occurs more commonly among staff physicians than trainees and among staff physicians more commonly in nonteaching compared with teaching institutions.

Drug treatment of pneumococcal pneumonia in the elderly

Streptococcus pneumoniae has been recognised as a major cause of pneumonia since the time of Sir William Osler. Drug-resistant S. pneumoniae (DRSP), which have gradually become resistant to penicillins as well as more recently developed macrolides and fluoroquinolones, have emerged as a consequence of indiscriminate use of antibacterials coupled with the ability of the pneumococcus to adapt to a changing antibacterial milieu. Pneumococci use cell wall choline components to bind platelet-activating factor receptors, colonise mucosal surfaces and evade innate immune defenses. Numerous virulence factors that include hyaluronidase, neuraminidase, iron-binding proteins, pneumolysin and autolysin then facilitate cytolysis of host cells and allow tissue invasion and bloodstream dissemination. Changes in pneumococcal cell wall penicillin-binding proteins account for resistance to penicillins, mutations in the ermB gene cause high-level macrolide resistance and mutations in topoisomerase IV genes coupled with GyrA gene mutations alter DNA gyrase and lead to high-level fluoroquinolone resistance. Risk factors for lower respiratory tract infections in the elderly include age-associated changes in oral clearance, mucociliary clearance and immune function. Other risks for developing pneumonia include poor nutrition, hypoalbuminaemia, bedridden status, aspiration, recent viral infection, the presence of chronic organ dysfunction syndromes including parenchymal lung disease and recent antibacterial therapy. Although the incidence of infections caused by DRSP is rising, the effect of an increase in the prevalence of resistant pneumococci on mortality is not clear. When respiratory infections occur, rapid diagnosis and prompt, empirical administration of appropriate antibacterial therapy that ensures adequate coverage of DRSP is likely to increase the probability of a successful outcome when treating community-acquired pneumonia in elderly patients, particularly those with multiple risk factors for DRSP. A chest x-ray is recommended for all patients, but other testing such as obtaining a sputum Gram's smear is not necessary and should not prolong the time gap between clinical suspicion of pneumonia and antibacterial administration. The selection of antibacterials should be based upon local resistance patterns of suspected organisms and the bactericidal efficacy of the chosen drugs. If time-dependent agents are chosen and DRSP are possible pathogens, dosing should keep drug concentrations above the minimal inhibitory concentration that is effective for DRSP. Treatment guidelines and recent studies suggest that combination therapy with a beta-lactam and macrolide may be associated with a better outcome in hospitalised patients, and overuse of fluoroquinolones as a single agent may promote quinolone resistance. The ketolides represent a new class of macrolide-like antibacterials that are highly effective in vitro against macrolide- and azalide-resistant pneumococci. Pneumococcal vaccination with the currently available polysaccharide vaccine is thought to confer some preventive benefit (preventing invasive pneumococcal disease), but more effective vaccines, such as nonconjugate protein vaccines, need to be developed that provide broad protection against pneumococcal infection.

Empiric treatment of ambulatory community-acquired pneumonia: always include treatment for atypical agents

There are no data from proper studies to answer whether it is necessary to include antibiotics that are active against atypical pneumonia agents as part of the empiric therapy of CAP. Until such data are available, clinical judgment and severity of the pneumonic illness are the best guides to empiric antimicrobial therapy.

Nonresponses and treatment failures with conventional empiric regimens in patients with community-acquired pneumonia

Although most patients with suspected CAP respond to empiric therapy,a small number of patients do not respond in the expected fashion. Age and underlying comorbid conditions have a strong influence on the course of illness. Less common causes of treatment failures include overwhelming infection, antimicrobial resistance, and misdiagnosis. It is a common practice for empiric antimicrobial treatment of CAP to be initiated without microbiologic studies. Clinicians carefully should observe these patients for unusual or slow responses and should be ready to pursue a more extensive search for the cause of treatment failure.

Antimicrobial therapy of community-acquired pneumonia

Community-acquired pneumonia (CAP) is a common disorder that is potentially life-threatening, especially in older adults and patients with comorbid disease. Despite substantial progress in therapeutic options, CAP remains a primary cause of death from infectious disease in the United States. The mainstay of treatment for most patients is appropriate antimicrobial therapy This article reviews the principles for initial antimicrobial therapy, highlights some of the differences in approaches to antimicrobial drug selection in selected guidelines, and includes new recommendations for empiric and pathogen-directed therapy of CAP.

Effect of formulary policy decisions on antimicrobial drug utilization in British Columbia

BACKGROUND

Formularies are used routinely for management of drug expenditures yet evaluations of their impact remain rare. The objective of this study was to analyse the impact of addition or deletion of antimicrobials from the provincial formulary on drug utilization.

METHODS

We obtained data from the British Columbia PharmaNet database on all outpatient oral antimicrobial prescriptions from 1996 to 2000 and converted them to their defined daily dose (DDD) equivalents according to the ATC system. Trends in utilization associated with a changing formulary status of new antimicrobial agents were analysed. Maximum likelihood estimation was used to determine the rate of increase in utilization resulting from addition to the formulary. Models were adjusted for seasonal and temporal trends as well as serial correlation.

RESULTS

During this time period, clarithromycin was on formulary, later delisted, and then relisted again. Valaciclovir and famciclovir were also added to the formulary. During the time clarithromycin was off the formulary, the rate of change in its monthly consumption was 0.0061 DDD/1000 population/day; following its relisting, the rate of change increased by 818% to 0.0560 DDD/1000 population/day (P=0.002). After the listing of valaciclovir on the formulary, the rate of change in its monthly consumption increased 57% from a baseline of 0.0014 to 0.0022 DDD/1000 population/day (P=0.07). A similar effect was seen with the addition of famciclovir to the formulary whereby the rate of change in monthly consumption increased from 0.0008 (before addition to the formulary) to 0.0018 (after addition to the formulary) (P </= 0.001).

CONCLUSIONS

Listing of antimicrobials on provincial or countrywide formularies is followed temporally with increased utilization. However, before governmental agencies can institute reference-based pricing or co-payment programmes, the effect of such a programme on the emergence of antimicrobial resistance and on patient outcomes needs further study.

Use of Macrolides and Tetracyclines for Chronic Inflammatory Diseases

OBJECTIVE:

To review the efficacy of macrolides and tetracyclines in several chronic inflammatory conditions.

DATA SOURCES:

Searches of MEDLINE (1966–March 2004) and an extensive bibliography search were undertaken. Key terms included acne, blepharitis, cardiovascular disease, cystic fibrosis, periodontitis, rosacea, and rheumatoid arthritis.

STUDY SELECTION AND DATA EXTRACTION:

Data were obtained primarily from randomized placebo-controlled trials upon which key recommendations are based.

DATA SYNTHESIS:

Antibiotics are often prescribed for months or even years for treatment of chronic inflammatory conditions such as acne, blepharitis, cardiovascular disease, cystic fibrosis, periodontitis, rosacea, and rheumatoid arthritis. Randomized controlled trials have shown that azithromycin is useful in the management of cystic fibrosis and the tetracyclines are beneficial in the management of rheumatoid arthritis, acne, blepharitis, and periodontitis. Several large, randomized controlled trials have failed to show any benefit of macrolides in the secondary prevention of cardiovascular disease. No randomized placebo-controlled clinical trials have been performed to assess the efficacy of macrolides or tetracyclines in patients with rosacea.

CONCLUSIONS:

The use of tetracyclines and macrolides for rosacea is based primarily on anecdotal reports or open-label trials. Limited clinical trials support the use of tetracyclines or macrolides in acne, blepharitis, periodontitis, rheumatoid arthritis, and cystic fibrosis. Trials to date do not support the use of antibiotics for secondary prevention of cardiovascular disease.

Antibiotic prescribing rates in the US ambulatory care setting for patients diagnosed with influenza, 1997-2001

To document the rate and cost of antibiotic prescribing for patients diagnosed only with influenza during US ambulatory care visits. Federal survey data for 1997-2001 were used to estimate outpatient trends for all patients and healthy people age 5-49 years. Cost estimates were based on Medicare payments and Red Book average wholesale prices in 2003. Antibiotic prescribing for influenza is widespread; 38% of visits led to an antibiotic prescription of which one-third were for broad spectrum antibiotics. Inappropriate antibiotics cost dollar 18.5 million annually and may contribute to resistance. Increased vaccination rates and viral testing could reduce these trends.

Community-Based Surveillance in the United States of Macrolide-Resistant Pediatric Pharyngeal Group A Streptococci during 3 Respiratory Disease Seasons

BACKGROUND

In 2001, a total of 48% of pharyngeal group A streptococci (GAS) from Pittsburgh children were macrolide resistant. We assessed macrolide resistance, resistance genes, and emm types among GAS in the United States.

METHODS

In prospective, multicenter, community-based surveillance of pharyngeal GAS recovered from children 3-18 years old during 3 respiratory seasons (the 2000-2001 season, the 2001-2002 season, and the 2002-2003 season), GAS were tested for macrolide resistance and underwent emm gene sequencing. Macrolide-resistant GAS were tested for resistance to clindamycin, and resistance genes were determined.

RESULTS

Erythromycin resistance was observed in 4.4% of isolates from the 2000-2001 season, 4.3% from the 2001-2002 season, and 3.8% from the 2002-2003 season (P=.80). Clindamycin resistance was found in 1.04% of isolates; annual rates of clindamycin resistance were stable (P=.75). The predominant resistance genotype each year was mef A (65%-76.9%; overall, 70.3%). Resistant isolates included strains representing 8-11 different emm types each year. Heterogeneity of emm subtypes, resistance genes, and clindamycin resistance was evident among resistant isolates within some emm types. Geographic variability in resistance rates was present each year.

CONCLUSIONS

The macrolide resistance rate among pharyngeal GAS was <5% and was stable over the 3 seasons. However, rates varied among sites each year. There was no evidence of spread of a specific resistant clone, increasing clindamycin resistance, or escalation in median erythromycin MICs.

Pathogens resistant to antimicrobial agents: epidemiology, molecular mechanisms, and clinical management

Resistance to antimicrobial drugs is increasing at an alarming rate among both gram-positive and gram-negative bacteria. Traditionally, bacteria resistant to multiple antimicrobial agents have been restricted to the nosocomial environment. A disturbing trend has been the recent emergence and spread of resistant pathogens and resistance traits in nursing homes, the community, as well as in hospitals. This article reviews the epidemiology, molecular mechanisms of resistance, and treatment options for pathogens resistant to antimicrobial drugs.

Trends of penicillin and erythromycin resistance among invasive Streptococcus pneumoniae in Europe

OBJECTIVES

To forecast trends in resistance to penicillin and erythromycin among Streptococcus pneumoniae in Europe.

METHODS

Since 1999, the European Antimicrobial Resistance Surveillance System (EARSS) has collected routine antimicrobial susceptibility test results of S. pneumoniae. To observe and predict changes of reduced susceptibility over time, we used a multinomial logistic regression model.

RESULTS

Large variations in penicillin and erythromycin non-susceptibility were observed between countries, and reduced susceptibility to erythromycin (17%) has become more frequent than reduced susceptibility to penicillin (10%) in Europe overall. An overall decrease in single penicillin non-susceptibility, but an increase in dual non-susceptibility was observed, indicating a shift of single penicillin to combined non-susceptibility with erythromycin. By 2006, the proportion of single erythromycin and dual non-susceptibility could increase to as much as 20.4% and 8.9%, respectively.

CONCLUSIONS

Our results indicate that appropriately dosed beta-lactams for empirical therapy are still the treatment of choice, and that macrolides should be used with prudence.

Patterns of health care resource utilization after macrolide treatment failure: Results from a large, population-based cohort with acute sinusitis, acute bronchitis, and community-acquired pneumonia

BACKGROUND

Macrolide antibiotics are used as first-line therapy for the treatment of respiratory tract infections. The recent emergence of macrolide-resistant pathogens is a major concern.

OBJECTIVE

This study quantifies the frequency of macrolide treatment failure in respiratory infections and examines its impact on health care use.

METHODS

Patients with respiratory infections treated with macrolides in outpatient clinics from January to December 2002 were identified from a health insurance claims database. Macrolide treatment failure was defined as the receipt of a second antibiotic, different from the first, within 4 weeks after the initial macrolide. The end points were numbers of hospitalizations and emergency department and office visits within 1 month after the initial macrolide. We examined diagnostic codes on claim forms for posttreatment hospitalizations and visits to identify those most likely to be related to treatment failure as opposed to other causes. Utilization data were analyzed by Poisson regression to control for confounding variables.

RESULTS

The patients were divided into acute sinusitis (n = 111,135), acute bronchitis (n = 157,360), and community-acquired pneumonia (n = 36,212). Of these respective groups, 11,285 (10.2%), 15,498 (9.9%), and 4144 (11.4%) received a second antibiotic within 4 weeks. This subgroup with macrolide treatment failure was older, included more women, and had used more medical care before the index visit compared with patients with treatment success. After adjustment for age, sex, and previous health care use, patients experiencing treatment failure were more likely to be admitted to the hospital or to use emergency department or outpatient care after the index visit. This association was strongest for admissions and visits pertaining to the care of respiratory infections.

CONCLUSIONS

By our definition, about 10% of patients with respiratory infections who were treated with macrolide antibiotics experienced treatment failure within 4 weeks. Macrolide treatment failure was associated with increased health care utilization.

Immunomodulatory effects of macrolides: implications for practicing clinicians

Macrolides are regarded as the drugs of choice for the treatment of diffuse panbronchiolitis (DPB) due to their favorable effects on patient outcomes. These drugs decrease sputum production, thereby improving pulmonary function. Moreover, these effects are independent of dosing with respect to clarithromycin, erythromycin, and roxithromycin. The marked success of macrolides in this disease is a direct effect of impeding the inflammatory cascade. With their abilities to reduce the secretion of proinflammatory cytokines, ameliorate the infiltration of inflammatory cells into the airways, and reduce mucus secretion, macrolides are able to improve pulmonary function and quality of life in patients with chronic inflammatory diseases of the airways. Although prolonged use of macrolides raises concerns of increased adverse effects, data do not support such occurrences. With respect to concerns of resistance, it should be noted that in Japan, where macrolides are part of the treatment for DPB, these agents continue to be used effectively as antimicrobial agents. Therefore, the potential benefits of the immunomodulatory effects of macrolides in other conditions such as cystic fibrosis, chronic sinusitis, asthma, and chronic bronchitis are under investigation.

Increased use of second-generation macrolide antibiotics for children in nine health plans in the United States

BACKGROUND

Widespread use of broad-spectrum antibiotics contributes to increasing rates of bacterial resistance to antibiotics. Second-generation macrolides have become popular for use among children because of their broad spectrum and favorable dosing and side-effect profiles, although experts do not generally recommend them for use as initial treatment of infections among younger children.

OBJECTIVE

To assess trends in second-generation macrolide use from 1996 to 2000 among children treated as outpatients in 9 US health plans, including associated diagnoses and use as initial treatment.

METHODS

We sampled claims data for 25000 children, 3 months to <18 years of age, who were enrolled between September 1, 1995, and August 31, 2000, in each of 9 US health plans. Medications dispensed were linked with ambulatory visit claims to assign diagnoses. Dispensings without another antibiotic dispensing recorded in the previous 42 days were analyzed as initial treatment of a new illness episode. We analyzed trends in prescribing overall, for initial therapy, and, within specific diagnoses, for differences among health plans.

RESULTS

From 1995-1996 to 1999-2000, although overall antibiotic use decreased from 1.15 to 0.91 dispensings per person-year, second-generation macrolide use increased from 0.022 to 0.063 dispensings per person-year. Use as a proportion of all antibiotic dispensings increased from 1.9% to 6.9%, and use as initial therapy increased from 1.4% to 6%. For children <6 years of age, second-generation macrolide use as initial therapy increased from 0.9% to 5.0% for otitis media and from 5.2% to 24.0% for pneumonia. There was a wide range of prescribing rates among health plans during the last year of the study, from 0.006 to 0.135 dispensings per person-year.

CONCLUSIONS

Despite recent trends toward decreased antibiotic use among children, the use of second-generation macrolides among children has increased dramatically, even among younger children, for whom use for initial treatment of illness is not recommended. Large differences in prescribing rates exist among health plans. Continued efforts to promote the use of narrower-spectrum agents when appropriate are needed.

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'.

Fluoroquinolone and other antimicrobial resistance in invasive pneumococci, Hong Kong, 1995-2001

Fluoroquinolone resistance among invasive pneumococci in Hong Kong was high and a result of clonal expansion and spread.

We determined the susceptibilities of 265 invasive isolates of pneumococci obtained during 1995 to 2001 in Hong Kong to 11 antimicrobial agents and their serotypes. Overall, 62.6% isolates were susceptible to penicillin, 20% were intermediately resistant, and 17.4% were resistant. The overall prevalence of levofloxacin resistance (MIC >8 µg/mL) was 3.8% but increased to 15.2% among the penicillin-resistant isolates. All levofloxacin-resistant isolates were clonally related; had reduced susceptibility to penicillin, cefotaxime, and clarithromycin; and were derived from adults >50 years of age. Of the penicillin-nonsusceptible pneumococci, 90% from children <5 years of age and 54.8% from persons of all ages were of serotypes that are included in the 7-valent pneumococcal conjugate vaccine; 93.5% from children <5 years of age and 93% from persons of all ages were of serotypes that are included in the 23-valent polysaccharide vaccine.

Increase of resistance to macrolides in invasive Streptococcus pneumoniae in Spain (2000-2001)

This study examined the antimicrobial resistance of 1,278 invasive Streptococcus pneumoniae isolates from 41 Spanish laboratories participating in the European Antimicrobial Resistance Surveillance System (EARSS) during 2000 and 2001. Twenty-nine laboratories participated during both years and provided 950 of the isolates. Each laboratory used its own susceptibility testing methods. External quality assessment was performed annually by each participating laboratory. Significant increases in penicillin and erythromycin resistance were observed between 2000 and 2001. This increase was particularly noticeable in isolates from the laboratories participating during both years and in isolates from children and elderly patients.

In vitro antimicrobial susceptibilities of Streptococcus pneumoniae clinical isolates obtained in Canada in 2002

Empirical treatment is best guided by current surveillance of local resistance patterns. The goal of this study is to characterize the prevalence of antimicrobial nonsusceptibility within pneumococcal isolates from Canada. The Canadian Bacterial Surveillance Network is comprised of laboratories from across Canada. Laboratories collected a defined number of consecutive clinical and all sterile site isolates of S. pneumoniae in 2002. In vitro susceptibility testing was performed by broth microdilution with NCCLS guidelines. Rates of nonsusceptibility were compared to previously published reports from the same network. A total of 2,539 isolates were tested. Penicillin nonsusceptibility increased to 15% (8.5% intermediate, 6.5% resistant) compared to 12.4% in 2000 (P < or = 0.025, chi(2)). Only 32 (1.3%) isolates had an amoxicillin MIC of > or = 4 microg/ml and only 2 of 32 cerebrospinal fluid isolates had an intermediate susceptibility to ceftriaxone by meningeal interpretive criteria (MIC = 1 microg/ml). A total of 354 (13.9%) isolates were macrolide nonsusceptible (46.3% MLS(B), 56.7% M phenotype), increasing from 11.4% in 2000 (P < or = 0.0075, chi(2)). Only 13 (<1%) isolates had a telithromycin MIC of >1 microg/ml. Ciprofloxacin nonsusceptibility (defined as an MIC of > or = 4 microg/ml) increased to 2.7% compared to 1.4% in 2000 (P < or = 0.0025, chi(2)) and was primarily found in persons > or =18 years old (98.5%). Nonsusceptibility to penicillin, macrolides, and fluoroquinolones is increasing in Canada. Nonsusceptibility to amoxicillin and ceftriaxone remains uncommon. Newer antimicrobials such as telithromycin and respiratory fluoroquinolones have excellent in vitro activity.

Decrease in antibiotic use among children in the 1990s: not all antibiotics, not all children

BACKGROUND

Decreases in antibiotic use were widely reported in the 1990s. This study was undertaken to determine trends in the use of antibiotics from fiscal year (FY) 1995 (April 1995 to March 1996) to FY 2001 in a complete population of Manitoba children.

METHODS

Using Manitoba's health care databases, we determined annual population-based rates of antibiotic prescription among children by antibiotic class (narrow-spectrum and broader-spectrum antibiotics), age group, physician diagnosis (e.g., otitis media or bronchitis) and neighbourhood income in urban areas (derived from the 1996 census). Antibiotic prescription rates were generated within a generalized linear model framework with general estimating equations, and differences between FY 2001 and FY 1995 were tested. Differences in antibiotic use over time were compared across antibiotic classes, age groups, diagnoses and income neighbourhoods.

RESULTS

The overall antibiotic prescription rate decreased by almost one-third, from 1.2 prescriptions per child in FY 1995 to 0.9 prescriptions in FY 2001. Total antibiotic use declined for all respiratory tract infections; decreases were greatest for the sulfonamides (decrease to less than one-third the FY 1995 rate) and narrow-spectrum macrolides (decrease to less than half the FY 1995 rate). In contrast, the FY 2001 rate for broader-spectrum macrolides was as much as 12.5 times the FY 1995 rate. Otitis media accounted for one-quarter of the use of the latter agents. Preschool children and low-income children received the greatest number of antibiotic prescriptions. Declines in antibiotic prescriptions were of a lesser magnitude for low-income children (for whom rates in FY 2001 were four-fifths the rates in FY 1995) than for higher-income children (for whom rates in FY 2001 were about two-thirds the rates in FY 1995).

INTERPRETATION

Overall, antibiotic use declined over the late 1990s in this population of Canadian children, but the increasing use of broader-spectrum macrolides and higher rates of antibiotic use among preschool and low-income children may have implications for antibiotic resistance.

Review of treatment guidelines for community-acquired pneumonia

Community-acquired pneumonia (CAP) is a costly disease that is associated with significant morbidity and mortality. The growing prevalence of this disease has resulted in various advances in diagnosis and treatment. The most common pathogens of CAP include Streptococcus pneumoniae, Haemophilus influenzae, and atypical pathogens; however, the underlying pathogen often is unknown. Treatment of CAP has evolved because of changing etiologic patterns and increasing antimicrobial resistance among common respiratory pathogens. Among the groups that have established treatment guidelines for CAP are the American Thoracic Society (ATS), the Infectious Diseases Society of America (IDSA), and the Centers for Disease Control and Prevention (CDC). These guidelines establish risk factors associated with drug resistance or infection with specific pathogens. In addition, each guideline provides unique recommendations that are similar in some ways, yet different in others. By understanding the various risk factors for drug resistance and the treatment options endorsed by these guidelines, physicians can treat patients with the most appropriate antimicrobial available.

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.

Streptococcus pneumoniae: epidemiology and patterns of resistance

Streptococcus pneumoniae is a leading cause of bacterial pneumonia, meningitis, otitis media, and sinusitis; it results in significant morbidity and mortality in patients with pneumonia and meningitis. The pneumococcus is a common colonizing bacterium in the respiratory tract; it is especially common in the respiratory tracts of children, where it is frequently exposed to antimicrobial agents. This exposure can lead to resistance. Penicillin nonsusceptibility is found in nearly 40% of strains causing disease in adults, although often these cases are treatable with appropriate dosing regimens of many oral and parenteral beta-lactam agents. In the United States resistance to macrolides is widespread--averaging approximately 28%--but geographically variable, ranging from 23% in the northwest to 30% in the northeast. Resistance to tetracyclines and trimethoprim-sulfamethoxazole are reported in approximately 20% and 35% of isolates, respectively, and resistance to multiple classes of agents is increasingly common. Amoxicillin, amoxicillin-clavulanate, respiratory fluoroquinolones, and clindamycin are currently the most effective agents for treatment of respiratory tract infections caused by S pneumoniae, with >90% of isolates in the United States being susceptible. Vancomycin is the only agent against which resistance has not emerged. Patient groups that are at increased risk for developing resistant pneumococcal infections have been identified and include patients with malignancies, human immunodeficiency virus infection, and sickle-cell disease. Judicious use of antimicrobials is the key to preventing the emergence of further resistance, particularly as few new classes of agents are likely to become available for clinical use in the short term.

Developing community-specific recommendations for first-line treatment of acute otitis media: is high-dose amoxicillin necessary?

OBJECTIVES

National recommendations are to use high-dose amoxicillin (80-90 mg/kg per day) to treat uncomplicated acute otitis media (AOM) in children who are at high risk for infection with nonsusceptible Streptococcus pneumoniae (NSSP). However, high-dose treatment may not be necessary if the local prevalence of NSSP is low. The objective of this study was to estimate the local prevalence of NSSP in children with acute upper respiratory illnesses and to develop community-specific recommendations for first-line empiric treatment of AOM.

METHODS

We conducted a cross-sectional prevalence study in the offices of 7 community pediatricians in St Louis, Missouri. S pneumoniae was isolated from nasopharyngeal swabs collected from children who were younger than 7 years and had AOM, nonspecific upper respiratory infection, cough, acute sinusitis, or pharyngitis. Children were excluded from the study when they had received an antibiotic in the previous 4-week period. Parents and providers completed a brief questionnaire to assess risk factors for carriage of NSSP. On the basis of National Clinical Chemistry Laboratory Standards, isolates with a penicillin minimum inhibitory concentration > or =0.12 microg/mL were considered to be nonsusceptible to penicillin (NSSP), and isolates with a penicillin minimum inhibitory concentration >2 microg/mL were categorized as nonsusceptible to standard-dose amoxicillin (35-45 mg/kg per day; NSSP-A).

RESULTS

S pneumoniae was isolated from the nasopharynx of 85 (40%) of 212 study patients (95% confidence interval [CI]: 33%-47%); 41 (48%) of 85 isolates were NSSP (95% CI: 37%-59%), and 6 (7%) were NSSP-A (95% CI: 1.5%-13%). Among the 212 study patients, the prevalence of NSSP was 19% (95% CI: 14%-25%), and the prevalence of NSSP-A was 3% (95% CI: 0.6%-5%). Carriage of NSSP was increased in child care attendees compared with nonattendees (29% vs 14%; odds ratio: 2.6; 95% CI: 1.3-5.2).

CONCLUSIONS

In our community, although the prevalence of NSSP among isolates of S pneumoniae identified from the nasopharynx of symptomatic children is high (48%), the probability of NSSP-A infection among symptomatic children is <5%. Our data support a recommendation to treat most children who have uncomplicated AOM with standard-dose amoxicillin. Children who attend child care or have recently received an antibiotic may require treatment with high-dose amoxicillin. Other communities may benefit from a similar assessment of the prevalence of NSSP and NSSP-A.

Therapeutic implications of macrolide resistance in pneumococcal community-acquired lower respiratory tract infections

Macrolide anti-bacterials are widely used for the empirical treatment of lower respiratory tract infections (RTIs) due to their activity against Streptococcus pneumoniae and other common respiratory pathogens and good safety/tolerability profile. However, the prevalence of macrolide resistance, particularly pneumococcal macrolide resistance, is increasing all around the world. The mechanisms underlying macrolide resistance include efflux pump, methylase activity and, less commonly, ribosomal mutation, which produce differing levels of resistance. Growth in macrolide resistance has been linked to the increased use of these agents, and several risk factors for the development of resistance have been identified. There are emerging data to suggest that in vitro macrolide resistance may increase the likelihood of treatment failure in patients with lower RTIs. However, at present, treatment failure is rare and randomised; intervention-based trials investigating the impact of anti-bacterial resistance on clinical outcomes are lacking. Strategies to promote appropriate use of macrolides and other anti-bacterials are needed, both to maximise therapeutic impact and to minimise the development of resistance. Furthermore, there is a need for alternative anti-bacterial agents which have high efficacy against respiratory pathogens (including resistant strains) and a low potential to induce resistance.

Evolution of amoxicillin/clavulanate in the treatment of adults with acute bacterial rhinosinusitis and community-acquired pneumonia in response to antimicrobial-resistance patterns

Current treatment guidelines for community-acquired respiratory tract infections no longer depend solely on the characteristics of the patient and the clinical syndrome, but on those of the offending pathogen, including presence and level of antimicrobial resistance. The most common respiratory tract pathogens known to cause acute bacterial rhinosinusitis (ABRS) and community-acquired pneumonia (CAP) include Streptococcus pneumoniae and Haemophilus influenzae. The prevalence of antimicrobial resistance, especially b-lactum and macrolide resistance, among S pneumoniae and H influenzae has increased dramatically during the past 2 decades, diminishing the activity of many older antimicrobials against resistant organisms. A pharmacokinetically enhanced formulation of amoxicillin/clavulanate has been developed to fulfill the need for an oral b-lactam antimicrobial that achieves a greater time that the serum drug concentration exceeds the minimum inhibitory concentration (T > MIC) of antimicrobials against pathogens than conventional formulations to improve activity against S pneumoniae with reduced susceptibility to penicillin. The b-lactamase inhibitor clavulanate allows for coverage of b-lactamase-producing pathogens, such as H influenzae and M catarrhalis. This article reviews the rationale for, and evolution of, oral amoxicillin clavulanate for ABRS and CAP

Clinical relevance of antimicrobial resistance in the management of pneumococcal community-acquired pneumonia

Streptococcus pneumoniae remains the most common bacterial cause of community-acquired pneumonia, and these infections are associated with significant morbidity and mortality worldwide. A major concern is the increasing incidence of antibiotic resistance among pneumococcal isolates, which, in the case of certain of the antibiotic classes, has been associated with treatment failure. Yet despite multiple reports of infections with penicillin-resistant pneumococcal isolates, no cases of bacteriologic failure have been documented with the use of penicillin or ampicillin in the treatment of pneumonia caused by penicillin-resistant pneumococci. Current prevalence and levels of penicillin resistance among pneumococal isolates in most areas of the world do not indicate a need for substantial treatment changes with regard to the use of the penicillins. For infections with penicillin-sensitive strains, penicillin or an aminopenicillin in a standard dosage will still be effective for treatment. In the cases of strains with intermediate resistance, beta-lactam agents are still considered appropriate treatment, although higher dosages are recommended. Infections with isolates of high-level penicillin resistance should be treated with alternative agents such as the third-generation cephalosporins or the new antipneumococcal fluoroquinolones. In the case of the cephalosporins, pharmacodynamic/pharmacokinetic parameters help predict which of those agents are likely to be successful, and the less active agents should not be used. Debate continues in the literature with regard to the impact of macrolide resistance on the outcome of pneumococcal pneumonia, with some investigators providing evidence of an "in vivo-in vitro paradox," referring to discordance between reported in vitro resistance and clinical success of macrolides/azalide in vivo. However, several cases of macrolide/azalide treatment failure have been documented, and many clinicians recommend that these agents not be used on their own in areas with a high prevalence and levels of macrolide/azalide resistance. However, evidence is emerging to show beneficial effects on outcome with combination therapy, especially that of a beta-lactam agent and a macrolide given together to sicker, hospitalized patients with pneumococcal pneumonia. In an attempt to prevent the emergence of resistance, it has been recommended by some that the new fluoroquinolones not be used routinely as first-line agents in the treatment of community-acquired pneumonia; instead, they say, these agents should be reserved for patients who are allergic to the commonly used beta-lactam agents, for infections known to be or suspected of being caused by highly resistant strains, and for patients in whom initial therapy has failed.

Azithromycin compared with beta-lactam antibiotic treatment failures in pneumococcal infections of children

OBJECTIVE

To determine whether treatment failures occurred more commonly with azithromycin than with beta-lactam antibiotics in children who developed invasive pneumococcal disease within 30 days of receiving prior antimicrobial therapy.

METHODS

Retrospective review of medical records of children evaluated at Texas Children's Hospital between 1996 and 2002 who had received antimicrobials (azithromycin or a beta-lactam antibiotic) and developed invasive pneumococcal disease within 30 days. Treatment failure was defined as invasive pneumococcal infection that occurred while taking antimicrobials or within 3 days of stopping azithromycin treatment or 1 day of stopping beta-lactam treatment. Penicillin and azithromycin susceptibilities were determined and categorized according to National Committee for Clinical Laboratory Standards guidelines.

RESULTS

We identified 21 and 33 children with similar demographic features who had developed invasive pneumococcal disease within 1 month of receiving azithromycin or a beta-lactam antibiotic, respectively. Eleven (52%) children in the azithromycin group and 11 (33%) in the beta-lactam group met the definition for treatment failures (P = 0.34). Eight treatment failures while receiving azithromycin were caused by pneumococci with the macrolide-resistant (M) phenotype, 2 with the macrolide-, lincosamide- and streptogramin B-resistant (MLSB) phenotype and 1 by a macrolide-susceptible organism. In the beta-lactam group 7 had a penicillin-resistant isolate, 3 had an intermediately susceptible isolate and 1 had a susceptible isolate.

CONCLUSIONS

Our study suggests that treatment failures among patients who developed invasive disease within 30 days of receiving an antimicrobial occur as frequently in patients who receive beta-lactam antibiotics as in those who receive azithromycin. Furthermore macrolide resistant organisms are not more likely to be recovered after a macrolide treatment failure than a penicillin-nonsusceptible isolate being recovered after a beta-lactam treatment failure (P = 1.0).

Guidelines for Empiric Antimicrobial Prescribing in Community-Acquired Pneumonia

Empiric antimicrobial prescribing for community-acquired pneumonia remains a challenge, despite the availability of treatment guidelines. A number of key differences exist between North American and European guidelines, mainly in the outpatient setting. The North American approach is to use initial antimicrobial therapy, which provides coverage for Streptococcus pneumoniae plus atypical pathogens. Europeans tend to focus on providing pneumococcal coverage with less emphasis on covering for an atypical pathogen. Ambulatory patients without comorbidity are more likely to receive macrolide therapy in North America, whereas in Europe these patients would probably receive a beta-lactam agent. Major issues that are fundamental to this difference include the importance of providing therapy for atypical pathogens and the clinical significance of macrolide-resistant S pneumoniae. Prospective data are required to evaluate which of these two approaches offers clinical superiority.

Trends in Antimicrobial Drug Development: Implications for the Future

The need for new antimicrobial agents is greater than ever because of the emergence of multidrug resistance in common pathogens, the rapid emergence of new infections, and the potential for use of multidrug-resistant agents in bioweapons. Paradoxically, some pharmaceutical companies have indicated that they are curtailing anti-infective research programs. We evaluated the United States Food and Drug Administration (FDA) databases of approved drugs and the research and development programs of the world's largest pharmaceutical and biotechnology companies to document trends in the development of new antimicrobial agents. FDA approval of new antibacterial agents decreased by 56% over the past 20 years (1998-2002 vs. 1983-1987). Projecting future development, new antibacterial agents constitute 6 of 506 drugs disclosed in the developmental programs of the largest pharmaceutical and biotechnology companies. Despite the critical need for new antimicrobial agents, the development of these agents is declining. Solutions encouraging and facilitating the development of new antimicrobial agents are needed.

Drug‐Resistant Pneumococcal Pneumonia: Clinical Relevance and Related Factors

A multicenter study of 638 cases of community-acquired pneumonia due to Streptococcus pneumoniae (SP-CAP) was performed to assess current levels of resistance. Of the pneumococcal strains, 35.7% had an minimum inhibitory concentration (MIC) of penicillin of > or =0.12 microg/mL (3 isolates had an MIC of 4 microg/mL), 23.8% had an MIC of erythromycin of 128 microg/mL, and 22.2% were multidrug resistant. Logistic regression determined that chronic pulmonary disease (odds ratio [OR], 1.44], human immunodeficiency virus infection (OR, 1.98), clinically suspected aspiration (OR, 2.12), and previous hospital admission (OR, 1.69) were related to decreased susceptibility to penicillin, and previous admission (OR, 1.89) and an MIC of penicillin of MIC > or =0.12 microg/mL (OR, 15.85) were related to erythromycin resistance (MIC, > or =1 microg/mL). The overall mortality rate was 14.4%. Disseminated intravascular coagulation, empyema, and bacteremia were significantly more frequent among patients with penicillin-susceptible SP-CAP. Among isolates with MICs of penicillin of > or =0.12 microg/mL, serotype 19 was predominant and was associated with a higher mortality rate. In summary, the rate of resistance to beta -lactams and macrolides among S. pneumoniae that cause CAP remains high, but such resistance does not result in increased morbidity.