Practice guidelines for the management of community-acquired pneumonia in adults. Infectious Diseases Society of America

Epidemiology of clinically diagnosed community-acquired pneumonia in the primary care setting: results from the 1999-2000 respiratory surveillance program

To evaluate the prevalence of typical pathogens, level of resistance, and risk factors associated with community-acquired pneumonia (CAP) in the outpatient primary care setting and define current antibiotic treatment for office-based CAP, the Respiratory Surveillance Program (RESP) recruited 1,200 primary care clinics during the 1999-2000 respiratory infection season. Participating community-based physicians submitted sputum samples from patients presenting with a community-acquired respiratory infection including community-acquired pneumonia (CAP). All patients were aged > or =18 years. Patient demographics and risk factors were collected. Physicians express-mailed the specimens to a central laboratory for identification and susceptibility testing. All isolates were tested against a select panel of antimicrobial agents that are used to treat CAP. Patients with CAP were diagnosed by the treating physicians. Chest radiographs were not required as part of the study. A total of 610 specimens were submitted from patients with CAP. A smoking history or reported history of chronic obstructive pulmonary disease were present in >50% of those diagnosed with CAP. The most common pathogens were, in order of prevalence, Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis. During the study period, a variety of antibiotics were prescribed for the treatment of outpatient CAP. The top 3 prescribed antibiotics include levofloxacin (23%), clarithromycin (19%), and azithromycin (10%). Gatifloxacin, which was approved in December 1999 and therefore available for only part of the study, accounted for 4% of the prescriptions. Of S pneumoniae isolates, 8% demonstrated high-level resistance to penicillin (> or =2 microg/mL) and 33% were found resistant to macrolides and trimethoprim/sulfamethoxazole. All S pneumoniae isolates were sensitive to gatifloxacin, vancomycin, and levofloxacin. Other less common organisms isolated were staphylococci, streptococci, Enterobacteriaceae, Pseudomonas spp, and Acinetobacter spp. The choice of antibiotic to treat outpatient CAP varies from practice to practice and does not appear to be influenced by the patient's age, the patient's history of smoking, or comorbidity.

Gatifloxacin-associated acute hepatitis

Gatifloxacin, a fluoroquinolone with extended gram-positive activity, has become extensively used in both the community and hospital environments. Unfortunately, concerns have been raised about the use of certain fluoroquinolones because of adverse drug reactions. A 44-year-old woman developed acute hepatitis while receiving gatifloxacin for chronic sinusitis. After 5 days of receiving antibiotics, the patient developed nausea, lethargy, and abdominal pain, all of which progressed over the next few days. Liver function tests were elevated, with bilirubin peaking at 9.4 mg/dl. The patient also became jaundiced. A percutaneous liver biopsy showed acute hepatitis with eosinophilic infiltrates consistent with drug-induced hepatitis. All other drugs and disease processes were ruled out as likely causes of the patient's hepatitis. Clinicians should be alerted to the possibility that hepatitis may occur with gatifloxacin administration.

Community-acquired lower respiratory tract infections: etiology and treatment

The current therapy for community-acquired lower respiratory tract infections is often empiric, usually involving administration of a beta-lactam or macrolide. However, the increasing prevalence of antibiotic resistance in frequently isolated respiratory tract pathogens has complicated the antimicrobial selection process. This review will discuss the incidence of various respiratory pathogens, as well as update the clinician on the various antimicrobial alternatives available, with particular emphasis on the role of the newer fluoroquinolones in the treatment of acute exacerbations of chronic bronchitis and community-acquired pneumonia.

Assessment of a new test to detect Legionella urinary antigen for the diagnosis of Legionnaires' Disease

Given that the rate of mortality by Legionella pneumonia increases in incorrectly treated patients, rapid diagnosis and early antibiotic treatment are needed. We have assessed the performance of a new enzyme immunoassay (EIA) test (Bartels Inc. Trinity Biotech Company, Wicklow, Ireland) to detect Legionella pneumophila antigen in urine comparing it to Binax EIA (Binax, Portland, Maine). We also evaluated the capability of both EIAs to detect extracted soluble antigens of Legionella strains. Using nonconcentrated urine samples (NCU) the sensitivity of Bartels EIA was 74.1% (66/89) and the sensitivity of Binax EIA was 51.7% (46/89). The sensitivity of both EIA tests were 91.5% (54/59) using concentrated urine samples (CU). Specificity of both EIA tests was 100% in NCU and CU. Bartels EIA was able to detect all serogroup L. pneumophila antigens, achieving a higher sensitivity in the case of L. pneumophila serogroup 1 soluble antigen. The new EIA was found to be a useful test for the rapid diagnosis of Legionella pneumonia, being a better alternative to the Binax EIA if NCU is used.

Severe community-acquired pneumonia: current outcomes, epidemiology, etiology, and therapy

Severe community-acquired pneumonia is a clinical diagnosis with a significant impact on healthcare management around the world, with the highest morbidity and mortality of all of the forms of community-acquired pneumonia. Patients with severe pneumonia usually require intensive care unit management, including vasopressors or mechanical ventilation. Early clinical suspicion and prompt empiric antimicrobial therapies are mandatory in patients with severe pneumonia. A number of recent studies and guidelines addressing these issues have been published, and they will be reviewed in this article.

In vitro activity of ABT-773, telithromycin and eight other antimicrobials against erythromycin-resistant Streptococcus pneumoniae respiratory isolates of children

The activity of the ketolide ABT-773 against 180 erythromycin-resistant Streptococcus pneumoniae obtained from children was compared with telithromycin, azithromycin, clarithromyin, roxithromycin, clindamycin, penicillin, levofloxacin and gatifloxacin. Ketolide MICs were all < or =1 mg/l, with ABT-773 being the most potent of all drugs tested. MIC(90)s for macrolides and azithromycin in mefE+ isolates were 16-32 compared with >128 mg/l for ermB+ isolates. ABT-773 and telithromycin MIC(90)s for mefE+ isolates were 0.125 and 0.5, compared with 0.032 and 0.016 mg/l for ermB+ isolates and 0.5 and 1 mg/l, respectively, for isolates containing both genes. Clindamycin was active against mefE+ but not ermB+ isolates. 155 isolates were resistant to penicillin. All fluoroquinolone MICs were < 1 mg/l. Further studies of ketolides for treatment of paediatric S. pneumoniae infections are warranted.

Drugs in pregnancy. Respiratory disease

Respiratory illnesses are the commonest cause of patient visits to physicians. Although the common cold, sinusitis and bronchitis may be lacking in drama, they account for a substantial amount of morbidity among women of reproductive age and are frequently encountered by physicians caring for pregnant women. Present knowledge about the management of these common conditions and the safety of the medications often used to treat them are reviewed in this chapter. Asthma and community-acquired pneumonia are more serious respiratory illnesses that are also often encountered in pregnancy. Present evidence suggests that community-acquired pneumonia is best treated empirically, with additional investigation usually necessary only if there is a failure of initial treatment. The recognition of asthma as an inflammatory condition has led to a very specific approach to its management that can readily and safely be applied to the pregnant woman. Treatment of HIV and tuberculosis should not be withheld during pregnancy because of the life-threatening nature of these infections and the importance of preventing vertical transmission.

[Etiology of community-acquired pneumonia in ambulatory patients. Usefulness of a diagnostic investigation protocol using detection of Streptococcus pneumoniae and Legionella pneumophila antigens in urine samples]

BACKGROUND

To determine the etiology of community-acquired pneumonia (CAP) in ambulatory patients and to assess the efficiency of a diagnostic protocol by using tests to detect bacterial antigens in urine samples.

PATIENTS AND METHOD

One-year prospective study that included blood and sputum cultures, serologic studies, and detection of Legionella pneumophila and Streptococcus pneumoniae urinary antigens.

RESULTS

49 patients were recruited and an etiological diagnosis was attained in 34 (69%). Microorganisms most frequently isolated were S. pneumoniae (12 cases), Mycoplasma pneumoniae (7), Haemophilus influenzae (4), respiratory viruses (4) and Coxiella burnetii (3 cases).

CONCLUSIONS

By means of a non-invasive protocol with urinary antigen tests, a microbial etiology can be established in two thirds of patients with mild CAP. S. pneumoniae is the main cause of mild CAP.

Pneumonia in the elderly

Pneumonia is one of the commonest infections in elderly patients. The pathogens responsible for pneumonias in the elderly are the same as in younger adults. Because of associated cardiopulmonary disease and/or impaired host defenses, pneumonia in elderly patients is associated with increased mortality and morbidity compared to younger patients. The clinical importance of pneumonias in the elderly relates to age-dependent and pathologic changes in the immune system as well as the lungs. Pneumonias in the elderly may be classified, for clinical purposes, according to their location of acquisition, i.e. community-acquired pneumonias, nursing home-acquired pneumonias, or hospital-acquired pneumonias. The clinical presentation of pneumonias in the elderly may be difficult, due to pre-existing cardiopulmonary disease that mimics pneumonia. This review discusses the diagnostic and therapeutic approaches to elderly patients with pneumonia.

Guidelines for the management of community-acquired pneumonia. Current recommendations and antibiotic selection issues

Numerous guidelines for CAP have been developed, and although each is different, many principles are common to all recommendations. A guideline should focus on a wide range of issues surrounding the delivery of care, including advice about when to admit patients to the hospital or ICU; which antibiotic regimens to select for specific patient populations; which pathogens to target in empiric therapy; which diagnostic tests to order; how to assess the importance of specific causative pathogens, such as drug-resistant pneumococci, atypical pathogens, and gram-negative pathogens; how to evaluate the response to therapy and when to switch responding patients to oral therapy; and how to prevent CAP effectively through appropriate use of immunization against pneumococcus and influenza. Currently, many new antibiotic choices have emerged in the macrolide, quinolone, beta-lactam, ketolide, and oxazolidinone classes, and specific issues surrounding selection of these agents must be considered. All of the available data can be synthesized into a disease management guideline, and current therapy in the United States generally is consistent with existing recommendations. This consistency not only has led to more uniformity in patient care, but also has led to measurable benefits in patient outcomes, including reduced mortality for hospitalized patients with CAP. Guidelines not only are a useful tool for managing patients with CAP, but also they serve the purpose of defining current issues in patient care and stimulating the search for new tools and management approaches for this important clinical problem.

Evaluating quality indicators for patients with community-acquired pneumonia

BACKGROUND

Several organizations have published evidence-based quality indicators for community-acquired pneumonia (CAP). However, there is variability in the types of indicators presented between organizations and the level of supporting evidence for each of the indicators. A systematic review of the literature and relevant Internet Web sites was performed to identify quality indicators for CAP that have been proposed or recommended by organizations, and each of the indicators was then critically appraised, using a well-defined set of criteria.

METHODOLOGY

The MEDLINE, EMBASE, Best Evidence, and Cochrane Systematic Review databases and Internet Web sites were searched for articles and guidelines published between January 1980 and May 2001 to identify quality indicators for CAP and relevant evidence. Experts in the area of health services research were contacted to identify additional sources. A well-defined set of criteria was applied to evaluate each of the quality indicators.

RESULTS

The systematic review of the literature and Internet Web sites yielded 44 CAP-specific quality indicators. The critical appraisal of these indicators yielded 16 indicators that were supported by a study that identified an association between quality of care and the process of care or outcome measure, were applied to enough patients to be able to detect clinically meaningful differences, were clinically and/or economically relevant, were measurable in a clinical practice setting, and were precise in their specifications.

CONCLUSIONS

Many organizations recommend indicators for CAP. Indicators may serve as measures of clinical performance for clinicians and hospitals, may help in benchmarking, and may ultimately facilitate improvements in quality of care and cost reductions. However, CAP indicators often vary in their meaningfulness, scientific soundness, and interpretability of results. A set of five critical appraisal questions may assist in the evaluation of which quality indicators are most valid.

An emergency department-based randomized trial of nonbronchoscopic bronchoalveolar lavage for early pathogen identification in severe community-acquired pneumonia

STUDY OBJECTIVES

Many patients with community-acquired pneumonia are treated empirically without an aggressive search for causative pathogens, an approach adopted largely because of the costs and difficulties encountered during efforts to identify the causative organisms. Blood and sputum cultures are not sensitive, and the more invasive techniques of bronchoscopy and lung biopsy are generally time consuming and not cost-effective. The technique of nonbronchoscopic bronchoalveolar lavage (BAL) has been shown to accurately diagnose the causes of nosocomial pneumonia. The purpose of this study was to determine whether an emergency department-based BAL protocol would lead to more frequent isolation of pneumonia pathogens and result in more changes to tailored antibiotic therapy in comparison with standard care.

METHODS

We studied all adult patients admitted with a diagnosis of pneumonia who were tracheally intubated and who had obtainable familial consent in the ED of an urban county hospital from March 1998 to October 1999. Exclusions included antibiotic use within the past 5 days, pneumothorax, hemoptysis, or persistent hypoxia using 100% oxygen. Patients were randomized to standard care versus standard care plus BAL. Blood culture specimens were drawn from all patients before the initiation of antibiotics. All other diagnostic tests were ordered at the discretion of treating physicians. BAL fluid, sputum, and blood culture specimens were tracked, and patient antibiotic course was followed to assess any change in regimen.

RESULTS

Twenty-six of 64 patients evaluated for study participation met all eligibility criteria; 14 patients received standard care, and 12 patients received standard care plus BAL. Pneumonia pathogens were identified in 10 (83.3%) of 12 patients in the BAL group and in 4 (28.6%) of 14 patients in the standard care group (P =.007). Comparing BAL versus non-BAL groups, there was no significant difference in the likelihood of overall antibiotic regimen changes (P =.149), but there was a difference with regard to antibiotic changes made in patients with positive culture test results (P =.026). No major complications occurred with BAL catheterizations.

CONCLUSION

ED-based BAL catheterization allows for early identification of pathogens in severe community-acquired pneumonia, which leads to changes in antibiotic therapy.

Integrating fluoroquinolones into the hospital formulary

With the increasing availability of new agents, selection of fluoroquinolones for formulary inclusion can be difficult. Appropriate evaluation of the important characteristics (pharmacokinetic and pharmacodynamic properties, antimicrobial activity, efficacy, tolerability, cost) of these agents should allow selection of the most cost-effective ones. Evidence from in vitro studies and clinical trials indicates differences exist among fluoroquinolones, especially in terms of activity against gram-positive, aerobic organisms. For selected clinical situations, it may be important to choose an agent that is available in both intravenous and oral formulations. Comparative drug costs, as well as costs associated with potential clinical failure and adverse events, should be evaluated carefully. Dosage regimens should be considered, as shorter durations of therapy and less frequent dose administration may lead to reduced labor costs and increased patient compliance, thereby improving effectiveness and economic efficiency.

Efficacy and safety of oral and early-switch therapy for community-acquired pneumonia: a randomized controlled trial

PURPOSE

We sought to determine the safety, efficacy, and cost of oral therapy for patients with community-acquired pneumonia. In patients with nonsevere pneumonia, conventional (parenteral) treatment was compared with the oral route; in patients with severe pneumonia, conventional treatment was compared with early switch from parenteral to oral therapy.

SUBJECTS AND METHODS

We randomly assigned 85 hospitalized patients with nonsevere pneumonia to one of two groups: 41 received oral antimicrobials from admission, and 44 received parenteral antimicrobials until they had been afebrile for 72 hours before switching to oral treatment. We randomly assigned 103 patients with severe pneumonia who had initially been treated with parenteral antimicrobials to one of two groups: 48 were switched to oral therapy after 48 hours of treatment (early switch), and 55 received a full 10-day course of parenteral antibiotics.

RESULTS

Among patients with nonsevere pneumonia, there were no deaths in the oral treatment group, and one death (2%) in the parenteral treatment group (95% confidence interval [CI] for between-group [oral minus parenteral] difference: -7% to 2%, P = 0.3). The time to resolution of morbidity was < or =5 days in 34 (83%) patients in the oral treatment group and 39 (88%) patients in the parenteral treatment group (P = 0.5); there were treatment failures in 4 (10%) patients in the oral treatment group and 14 (32%) patients in the parenteral treatment group (P = 0.02). Among patients with severe pneumonia, there was one (2%) death in the early-switch group and no deaths in the full course of parenteral antibiotics groups (95% CI for between-group [early switch vs. full course] difference: -2% to 6%, P = 0.5). The time to resolution of morbidity was < or =5 days in 38 (79%) patients in the early-switch group and 41 (75%) in the full-course group (P = 0.3). There were 12 (25%) treatment failures in the early-switch group and 13 (24%) in the full-course group (P = 0.9). There were fewer adverse events in the oral and early-switch groups, primarily due to lower rates of infusion-related phlebitis. Significant cost savings, mainly due to a shorter hospitalization, occurred among patients with severe pneumonia in the early-switch group.

CONCLUSION

Inpatients with nonsevere community-acquired pneumonia can be effectively and safely treated with oral antimicrobials from the time of admission, whereas those with severe pneumonia can be treated with early-switch therapy.

Adherence to ATS guidelines for hospitalized patients with community-acquired pneumonia

OBJECTIVE

To compare outcomes of care and antibiotic utilization for community-acquired pneumonia (CAP) throughout a group of not-for-profit hospitals.

METHODS

A retrospective chart review of patients from community hospitals with a diagnosis of pneumonia at discharge admitted from December 1997 to May 1998. Data were collected based on American Thoracic Society (ATS) criteria.

RESULTS

Medical records of 330 patients were reviewed; mortality was 7%. Using ATS guidelines, 51 (15.5%) patients were not treated with recommended antimicrobial therapy. Of these patients, 14 had nonsevere cases of CAP and 37 cases were severe. Factors found to be associated with in-hospital mortality included nonadherence to ATS guidelines (OR 4.46; 95% CI 1.38 to 14.43), decreased urine output (OR 7.72; 95% CI 1.70 to 35.04), and increasing age (OR 1.06; 95% CI 1.01 to 1.12). Significant predictors of length of stay (LOS) included age, nonadherence to ATS criteria, suspected aspiration, discharge status, low pulse oximetry on admission, decreased urine output, use of vasopressor medications, and interstitial lung disease; More than 80% of patients had at least one culture performed, but only 27.5% of these cultures were positive. The most cpmmonly prescribed antibiotic was cefuroxime injection, representing 25% of the antibiotic orders.

CONCLUSIONS

Patients with CAP treated inconsistently with ATS guidelines had a 4.46-d higher risk of inpatient mortality and had significantly longer LOS.

Estudo de casos hospitalizados por pneumonia comunitária no período de um ano

Introdução: Apesar dos avanços obtidos nos métodos propedêuticos, cerca de 50% dos casos de pneumonia adquirida na comunidade não têm sua etiologia esclarecida, inclusive os hospitalizados. Apesar disso, a terapêutica adequada proporciona baixas taxas de mortalidade na maioria dos casos. Objetivos: Descrever a epidemiologia, formas de apresentação, o rendimento dos testes diagnósticos, a permanência hospitalar, a morbidade e mortalidade de 42 pacientes consecutivos, internados para tratamento de PAC. Métodos: Foram incluídos pacientes com quadro clínico compatível com PAC, opacidade radiológica pulmonar recente e com dois itens entre febre, tosse produtiva e leucocitose. A solicitação de exames complementares obedeceu à necessidade de cada caso. Resultados: Dos 42 pacientes, com idade de 64,7 ± 16,8 anos, 27 (64,3%) masculinos, 27 (64%) apresentavam co-morbidades. Dezessete (40,5%) estavam em uso de antibióticos à admissão. Pneumonia grave ocorreu em oito casos (19%); não houve diferença quanto à gravidade (p = 0,57) e permanência hospitalar (p = 0,25) entre os grupos > de 60 ou <= de 60 anos. A permanência hospitalar média foi de 14,3 ± 7,6 dias. Diagnóstico etiológico definitivo foi obtido em três casos: Legionella sp em dois, S. aureus em um caso. Em 31 (74%), manteve-se o antibiótico inicial; em 11 (26%) houve troca, seis (54,5%) devido à má resposta clínica e cinco (45,5%) devido ao resultado microbiológico. Hemoculturas foram feitas em 16 casos (38%), positivas em apenas um (6,3%). Nove amostras de escarro (9/22, 41%) foram validadas. Ocorreu um óbito (2,4%), por pneumonia grave, em um paciente com neoplasia. Conclusões: O diagnóstico etiológico em PAC, mesmo em internados, é obtido em uma minoria de casos, contribuindo para isso o uso concorrente de antibióticos. A terapêutica empírica adequada proporciona baixas taxas de mortalidade. Os testes diagnósticos devem ser empregados de maneira individualizada.

Rethinking recommendations for use of pneumococcal vaccines in adults

Streptococcus pneumoniae remains a major cause of disease worldwide; the emergence of antibiotic-resistant strains emphasizes the importance of disease prevention by use of vaccines. Recent studies have provided information that is useful for the evaluation of current vaccine recommendations. Recommendations target most people who are at high risk for invasive pneumococcal disease. However, higher risk has also been identified for African Americans and smokers, but these groups are not specifically targeted by current recommendations. The vaccine is effective against invasive disease in immunocompetent people, although studies in immunocompromised subjects have found few subgroups in which the vaccine appears to be effective. Questions with regard to optimal timing and indications for revaccination remain a challenge, because the duration of protection and effectiveness of revaccination remain unknown. New pneumococcal vaccines appear promising but will need to be tested against the performance of the polysaccharide vaccine. Improving delivery of the currently available pneumococcal polysaccharide vaccine to adults who will benefit should be a high priority.

Lack of pneumococcal antigenuria in infants immunized with heptavalent pneumococcal conjugate vaccine

The incidence and duration of pneumococcal antigenuria were determined in 21 infants who received the first dose of pneumococcal conjugate vaccine. Urine specimens collected from the study participants at 1, 3, 6 and 9 days after immunization did not reveal the presence of pneumococcal antigen.

Linezolid: a review of its use in the management of serious gram-positive infections

Linezolid is the first of a new class of antibacterial drugs, the oxazolidinones. It has inhibitory activity against a broad range of gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), glycopeptide-intermediate S. aureus (GISA), vancomycin-resistant enterococci (VRE) and penicillin-resistant Streptococcus pneumoniae. The drug also shows activity against certain anaerobes, including Clostridium perfringens, C. difficile, Peptostreptococcus spp. and Bacteroidesfragilis. In controlled phase III studies, linezolid was as effective as vancomycin in the treatment of patients with infections caused by methicillin-resistant staphylococci and also demonstrated efficacy against infections caused by VRE. Further phase III studies have demonstrated that linezolid is an effective treatment for patients with nosocomial pneumonia, for hospitalised patients with community-acquired pneumonia, and for patients with complicated skin or soft tissue infections (SSTIs). In these studies, linezolid was as effective as established treatments, including third-generation cephalosporins in patients with pneumonia, and oxacillin in patients with complicated SSTIs. Oral linezolid 400 or 600mg twice daily was as effective as clarithromycin 250mg twice daily or cefpodoxime proxetil 200mg twice daily in the treatment of patients with uncomplicated SSTIs or community-acquired pneumonia. Linezolid is a generally well tolerated drug. The most frequently reported adverse events in linezolid recipients were diarrhoea, headache, nausea and vomiting. Thrombocytopenia was also documented in a small proportion (about 2%) of patients treated with the drug.

CONCLUSIONS

Linezolid has good activity against gram-positive bacteria, particularly multidrug resistant strains of S. aureus (including GISA), Enterococcus faecium and E. faecalis (including VRE). In controlled clinical trials, linezolid was as effective as vancomycin in eradicating infections caused by methicillin-resistant Staphylococcus spp. and has demonstrated efficacy against infections caused by VRE. As the level of resistance to vancomycin increases among S. aureus and enterococci, linezolid is poised to play an important role in the management of serious gram-positive infections.

Rationale for treating community-acquired lower respiratory tract infections with amoxicillin/sulbactam combination through pharmacodynamic analysis in the setting of aminopenicillin-resistant organisms

In order to establish a rationale for treating community-acquired lower respiratory tract infections, we assess here the pharmacodynamics of amoxicillin/sulbactam, 500mg/500mg, a formulation marketed in Argentina since 1988 and currently available in 17 countries, against the major pathogens, in comparison with that of a novel formulation (875mg/125mg, see J Chemother 2000; 12: 223-227). In time-kill studies, both bactericidal and inhibitory activity were seen in the 1.5- and 6-h sera, obtained from 12 volunteers after a single oral dose, against both a penicillin-susceptible and an -intermediate Streptococcus pneumoniae strain, as well as against Moraxella catarrhalis and a beta-lactamase-negative Haemophilus influenzae strain. Only the 1.5-h sera proved bactericidal against a penicillin-resistant S. pneumoniae strain (MIC, 2 microg/ml) and a beta-lactamse-positive H. influenzae isolate. This study suggests that amoxicillin/sulbactam (500mg/500mg) is still a suitable option for treating community-acquired lower respiratory tract infections, allowing a b.i.d. dosing schedule. Caution should be taken with pneumonia caused by beta-lactamase-positive H. influenzae or penicillin-resistant (MIC > or =2 microg/ml) S. pneumoniae isolates. Either shorter dosing intervals (t.i.d.) or a higher amoxicillin content in the formulation (i.e. 875 mg) may be required in these situations.

Fluoroquinolone susceptibility, resistance, and pharmacodynamics versus clinical isolates of Streptococcus pneumoniae from Indiana

The in vitro activity and pharmacodynamics (AUC(0-24)/MIC) of levofloxacin, gatifloxacin, moxifloxacin, and gemifloxacin were evaluated against 307 clinical isolates of Streptococcus pneumoniae from Indianapolis, Indiana. Organisms were collected between January 1999 and April 2000, and MICs were determined by broth microdilution. Serum concentration-time profiles were simulated for the following oral regimens administered once daily: levofloxacin 500 mg and 750 mg; gatifloxacin 400 mg; moxifloxacin 400 mg; gemifloxacin 320 mg. Free 24 h area under the serum concentration-time curves (AUC(0-24)) were calculated, and the average AUC(0-24)/MIC was calculated for each regimen. Differences in AUC(0-24)/MIC among agents were determined by analysis of variance (Scheffe post-hoc test, p < 0.05). Overall, gemifloxacin was the most potent agent tested. Five (1.7%), 4 (1.3%), and 2 (0.7%) isolates were resistant to levofloxacin, gatifloxacin, and moxifloxacin, respectively. None of the isolates was resistant to gemifloxacin. Gemifloxacin AUC(0-24)/MIC was significantly greater than all other regimens (p < 0.0001), with the exception of moxifloxacin. However, the percent of isolates for which an AUC(0-24)/MIC >or= 30-50 can be achieved is similar for gemifloxacin, moxifloxacin, gatifloxacin, and levofloxacin 750 mg. Large comparative studies are needed to determine if the differences in AUC(0-24)/MIC among fluoroquinolones are clinically significant.

Empiric antibiotic therapy and mortality among medicare pneumonia inpatients in 10 western states : 1993, 1995, and 1997

STUDY OBJECTIVES

To examine the association of empiric inpatient antibiotic treatment of community-acquired pneumonia (CAP) with mortality, and whether this association varies from year to year.

DESIGN

Population-based, retrospective study adjusting for demographics, comorbidities, and clinical characteristics.

SETTING

Acute-care hospitals in 10 western states.

PATIENTS

A group of 10,069 Medicare beneficiaries aged > or = 65 years who were hospitalized with CAP during fiscal years 1993, 1995, and 1997.

MEASUREMENTS AND RESULTS

We examined the risk for mortality during the 30 days after admission to the hospital. The impact of specific antibiotic regimens varied greatly from year to year. In 1993, therapy with a macrolide plus a beta-lactam was associated with significantly lower mortality than therapy with either a beta-lactam alone (adjusted odds ratio [AOR], 0.42; 95% confidence interval [CI], 0.25 to 0.69) or other regimens that did not include a macrolide, beta-lactam, or fluoroquinolone (AOR, 0.35; 95% CI, 0.20 to 0.62). Those associations were not observed in 1995 or 1997. Lower mortality was associated with fluoroquinolone monotherapy compared with beta-lactam monotherapy in 1997 (AOR, 0.27; 95% CI, 0.07 to 0.96) and with macrolide monotherapy compared with other regimens in 1995 (AOR, 0.24; 95% CI, 0.06 to 0.93), but the number of patients who received these regimens was small.

CONCLUSIONS

The inclusion of a macrolide or a fluoroquinolone in initial empiric CAP treatment was associated with improved survival, but this association varied from year to year, perhaps as a result of a temporal variation in the incidence of atypical pathogen pneumonia. Improved testing and surveillance for atypical pathogen pneumonia are needed to guide empiric therapy.

Intravenous-to-oral transition therapy in community-acquired pneumonia: the INOVA Health System experience

Economic pressures on the delivery of health care have necessitated a focus on reducing costs and resource utilization while maintaining or improving the quality of care. A growing consensus holds that switching from intravenous to oral therapy is a cost-effective and clinically sound approach for a significantly large group of patients with community-acquired pneumonia (CAP). Drug utilization studies within the INOVA Health System revealed that levofloxacin is a cost-effective alternative to ciprofloxacin in infectious disease and that use of risk prediction criteria can reduce inappropriate hospitalizations for CAP, thereby reducing costs. In addition, the INOVA experience demonstrates that the strategy used to implement new antibiotic regimens such as switch-therapy regimens is an important factor in cost reduction: a therapeutic interchange mandate is more successful than standard educational techniques in changing treatment patterns.

Efficacy and safety of gemifloxacin 320 mg once-daily for 7 days in the treatment of adult lower respiratory tract infections

An open-label, non-comparative study assessed the clinical and bacteriological efficacy of gemifloxacin (320 mg, once-daily for 7 days) in lower respiratory tract infections (LRTI). Patients with acute exacerbation of chronic bronchitis (AECB, n=261) or community-acquired pneumonia (CAP, n=216) were enrolled into the study. Clinical success rates at follow-up (days 21-28) in the intent-to-treat (ITT) population were high, 83.1% in AECB patients (95% CI: 77.9, 87.4) and 82.9% in CAP patients (95% CI: 77.0, 87.5). High bacteriological success rates were achieved (bacteriological ITT population), 91.2% (52/57) in AECB patients (95% CI: 80.0, 96.7) and 77.9% (60/77) in CAP patients (95% CI: 66.8, 86.3). Gemifloxacin was well tolerated with a low incidence of adverse events. Gemifloxacin treatment resulted in high clinical and bacteriological success rates and is a well-tolerated therapy for the treatment of LRTIs.

Clinical policy for the management and risk stratification of community-acquired pneumonia in adults in the emergency department

This clinical policy represents an approach that emphasizes key clinical information to determine the severity of CAP. By using this approach, a determination of whether the patient can be treated as an outpatient or inpatient may be made. Recommendations about the utility of ancillary studies and the use of antibiotics are also given. As more of the questions are answered through controlled studies, an evidence-based approach to this problem will become increasingly important in improving the outcome of patients with CAP.

The use of fluoroquinolones as antiinfective transition-therapy agents in community-acquired pneumonia

The newer quinolone antibiotics, including levofloxacin, moxifloxacin, and gatifloxacin, offer coverage of the likely pathogens in community-acquired pneumonia (CAP) and have been shown to be safe and effective treatments for CAP. Two of these agents, levofloxacin and gatifloxacin, have pharmacokinetic and antibacterial properties that are similar in both oral and intravenous formulations. As such, they may be excellent candidates for transition therapy involving early switch from intravenous to oral therapy followed by early hospital discharge for patients with CAP

New directions in antiinfective therapy for community-acquired pneumonia in the emergency department

The emergency department is becoming an increasingly important setting for the management of community-acquired pneumonia (CAP). This trend reflects the shortened hospital stays and decreased mortality among elderly hospitalized patients resulting from rapid administration of antimicrobials. In addition, decisions about the site of care (inpatient vs outpatient) and antimicrobial therapy frequently are made in the emergency department. Recent research and subsequent clinical guidelines may help with these decisions. For example, recently issued guidelines, such as those of the Infectious Diseases Society of America and the American Thoracic Society, suggest that selection of antimicrobials for CAP (which is typically empiric) should be based on the potential pathogens and likelihood of antimicrobial resistance. Macrolides and tetracyclines are recommended in younger patients with mild-to-moderate disease. Patients with more severe disease and those at risk for drug-resistant pathogens should be treated with broad-spectrum therapy, such as a newer fluoroquinolone or a cephalosporin plus a macrolide. When hospitalization is required, early switch from intravenous to oral therapy, followed by early discharge, can be a highly successful strategy. Antimicrobials that are available in both intravenous and oral formulations, such as the newer fluoroquinolones (e.g., levofloxacin and gatifloxacin), can simplify switch therapy For outpatients, an initial long-acting parenteral dose of azithromycin, ceftriaxone, or levofloxacin followed by oral therapy is an effective protocol. In addition, use of a prediction rule to identify low-risk patients with CAP may help guide decisions about the need for hospital admission.

Management of parapneumonic pleural effusion

Parapneumonic pleural effusion is a common and potentially serious complication of pneumonia. The management of parapneumonic pleural effusion involves early diagnosis, adequate empiric antibiotic cover, and appropriate risk categorization. High-risk patients require safe and expedient drainage of the infected pleural space. The management options include thoracentesis, tube thoracostomy, adjunctive intrapleural fibrinolytic therapy, and surgical drainage. The methods of surgical drainage include thoracoscopy, thoracotomy, and decortication. The relative clinical efficacy of these treatment options has been studied in a small number of controlled clinical trials, the results of which have been systematically reviewed by expert panels. Based on the limited clinical evidence, expert reviewers were unable to recommend a best method of pleural drainage. However, the consensus is that an aggressive approach with early surgical drainage results in shorter hospital stays and may be more cost-effective than conservative management. This review discusses the clinical evidence and describes an aggressive sequential management strategy that combines intrapleural fibrinolysis with early surgical drainage.

Levofloxacin failure in a patient with pneumococcal pneumonia

OBJECTIVE

To report a case of levofloxacin failure in a patient with a penicillin-sensitive Streptococcus pneumoniae pneumonia.

CASE SUMMARY

A previously healthy, immunocompetent, 53-year-old white man presented with penicillin-sensitive S. pneumoniae pneumonia. The patient was empirically placed on levofloxacin monotherapy, which was continued due to a local penicillin shortage. When the patient failed to improve, further susceptibility testing was ordered. The organism was found to have a penicillin minimum inhibitory concentration (MIC) of 0.023 microgram/mL and a levofloxacin MIC of 6 micrograms/mL. Effective antimicrobial therapy was delayed, as clinicians did not anticipate fluoroquinolone resistance.

DISCUSSION

Newer fluoroquinolones such as levofloxacin have good activity against most S. pneumoniae isolates and are used for the treatment of pneumonia. Although resistance to these agents is rare, it has been reported. Current guidelines from the National Committee for Clinical Laboratory Standards do not recommend initial fluoroquinolone susceptibility testing.

CONCLUSIONS

As fluoroquinolone resistance may not be identified by susceptibility patterns to other antibiotics, early fluoroquinolone susceptibility testing and increased awareness of resistance may aid clinicians in their treatment of pneumococcal disease.

Cost-effectiveness of Gatifloxacin vs Ceftriaxone With a Macrolide for the Treatment of Community-Acquired Pneumonia

STUDY OBJECTIVE

To determine the cost-effectiveness of sequential IV to oral gatifloxacin therapy vs IV ceftriaxone with or without IV erythromycin to oral clarithromycin therapy to treat community-acquired pneumonia (CAP) patients requiring hospitalization.

PATIENTS

Two hundred eighty-three patients enrolled in a randomized, double-blind, clinical trial were eligible for inclusion in the cost-effectiveness analysis.

METHODS

Data collected included patient demographics, clinical and microbiological outcomes, length of stay (LOS), and antibiotic-related LOS (LOSAR). Costs evaluated include drug acquisition (level 1); plus costs of preparation, dispensing, and administration, treating adverse events, and clinical failures (level 2); plus hospital per diem costs (level 3). Robustness of economic findings was tested using sensitivity analyses.

RESULTS

Two hundred three patients were clinically and economically evaluable (98 receiving gatifloxacin and 105 receiving ceftriaxone). IV erythromycin was administered to 35 patients in the ceftriaxone-treated group. Oral conversion was achieved in 98% of patients in each group. Clinical cure and microbiological eradication rates did not differ statistically (98% and 97% with gatifloxacin vs 92% and 92% with ceftriaxone, respectively). Overall, neither geometric mean LOS nor LOSAR differed significantly (4.2 days and 4.1 days with gatifloxacin vs 4.9 days and 4.9 days with ceftriaxone, respectively). Treatment failures in the ceftriaxone group contributed to a mean incremental increase in LOSAR of 1.09 days and increased mean cost per patient. The geometric mean costs per patient (level 3) were $5,109 for gatifloxacin and $6,164 for ceftriaxone (p = 0.011). The cost-effectiveness ratios (mean cost per expected success) were $5,236:1 and $7,047:1 for gatifloxacin and ceftriaxone, respectively.

CONCLUSIONS

Gatifloxacin monotherapy for CAP patients requiring hospitalization is clinically effective and provides an economic advantage compared to the regimen of ceftriaxone with or without erythromycin IV with a switch to oral clarithromycin.

Anaerobic pleuropulmonary infection

Obligate anaerobes are the predominant constituents of normal oropharyngeal flora and produce pleuropulmonary infection in patients who are prone to aspirate. Obtaining material from these patients for culture from the site of infection that is uncontaminated by normal flora is problematic. In-vitro cultivation of obligate anaerobes requires rigorous anaerobic techniques and susceptibility testing of obligate anaerobes is not standardized in many clinical microbiology laboratories. Few clinical trials of drugs have been done in patients with laboratory documented or putative anaerobic pulmonary infection. For these reasons the diagnosis and therapy of anaerobic pulmonary infection are frequently empirical and guided by published studies of in-vitro activity against collected clinical isolates. Several new drugs that have in-vitro activity against obligate anaerobes have recently become available for empirical treatment of pneumonia.

Mycoplasma pneumoniae infections

Mycoplasma pneumoniae is a frequent cause of community-acquired respiratory infections in children and adults. Although the organism is felt to be the most frequent 'atypical' pathogen responsible for community-acquired pneumonia in adults, the prevalence of M. pneumoniae varies greatly from study to study, depending on the population and the diagnostic methods used. Recent studies have found the prevalence of M. pneumoniae in adults with pneumonia to range from 1.9 to over 30%. M. pneumoniae is also a frequent cause of outbreaks of respiratory disease in institutional settings. However, the diagnosis of M. pneumoniae infection is hampered by the lack of standardized, rapid, specific methods. This problem was illustrated by the results of an investigation of an outbreak of M. pneumoniae infection in a federal training facility. Accurate diagnosis required a combination of polymerase chain reaction and serology, as IgM antibodies were not present early in the course of the infection in many patients. Several papers evaluating various serological and polymerase chain reaction assays were published during the period of this review. An assessment of the actual performance of these tests was also hampered by the lack of standardized comparative methods. M. pneumoniae is susceptible in vitro to macrolides, tetracyclines and quinolone antibiotics; however, data are limited on the microbiological efficacy of these agents. Several pneumonia treatment studies were published during this period, practically all of them based the diagnosis of M. pneumoniae infection on serology; different methods and criteria were used in each study, and thus the microbiological efficacy could not be assessed. The Infectious Disease Society of America recently stated in their revised Practice Guidelines for the Management of Community-Acquired Pneumonia in Adults that, as there were no diagnostic tests available that reliably and rapidly detect M. pneumoniae, therapy must usually be empirical.

Pharmacokinetic and pharmacodynamic properties of antimicrobials in the therapy of respiratory tract infections

Antimicrobial pharmacodynamics examines the relationship between the pharmacokinetics of a drug over time and its treatment effect. Pharmacokinetic/pharmacodynamic parameters have been shown to be predictors of the antimicrobial activity of a variety of drugs. The pharmacodynamic parameter linked to efficacy has been demonstrated to vary for different antimicrobial classes. Within an antimicrobial class, the magnitude of the pharmacodynamic parameter predictive of efficacy has been shown to be similar, as long as free-drug levels in serum are considered. Treatment outcome predictions based upon parameter magnitudes have correlated well and have been useful for assessing the future course of both susceptible and resistant pathogens of the respiratory tract. This has been useful for the development of susceptibility breakpoints and antimicrobial treatment guidelines. Recent studies have begun to investigate the relationship between antimicrobial pharmacodynamics and the prevention of drug resistance.

An update on community-acquired pneumonia in adults

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality, despite effective therapies. Guidelines for CAP management vary widely in their approach. Resistance of S pneumoniae to penicillins and other antibiotics has prompted evaluation of the new fluoroquinolones.

Clinical experience in Germany of treating community-acquired respiratory infections with the new 8-methoxyfluoroquinolone, moxifloxacin

Moxifloxacin, a new 8-methoxyfluoroquinolone, was evaluated in a large community-based study involving 16,007 patients over a 9-month period. This study was designed as a large post-marketing observational study of the speed, efficacy and tolerability of moxifloxacin when used in clinical practice for the treatment of community-acquired bacterial pneumonia, or acute exacerbations of chronic bronchitis. Physicians and patients were specifically questioned about overall efficacy and safety as well as symptom relief. According to physicians' assessments 96.3% of patients were cured or improved after moxifloxacin treatment. Symptom relief ('feeling better') occurred in almost 70% of patients by day 3 and only 2.3% reported an adverse drug reaction. No individual adverse drug reaction was reported at a frequency above 1%. Among the 209 events considered as serious, only 34 were regarded as possibly or probably related to therapy. There were no moxifloxacin-related clinically relevant cases of phototoxicity, hepatotoxicity or cardiotoxicity. Overall, 92.1% of patients considered moxifloxacin to have been beneficial.

In vitro activity and pharmacodynamics of azithromycin and clarithromycin against Streptococcus pneumoniae based on serum and intrapulmonary pharmacokinetics

BACKGROUND

Multidrug-resistant strains of Streptococcus pneumoniae are increasingly common worldwide, but the clinical significance of their resistance to the macrolide antibiotics is controversial. Applying pharmacokinetic and pharmacodynamic principles can assist in the selection of appropriate antimicrobial therapy.

OBJECTIVES

The purpose of this study was to determine the in vitro activity of penicillin, azithromycin, clarithromycin, and clindamycin against clinical isolates of S. pneumoniae and to evaluate the pharmacodynamics of azithromycin and clarithromycin based on serum and epithelial lining fluid (ELF) concentrations.

METHODS

The minimum inhibitory concentrations (MICs) of penicillin, azithromycin, clarithromycin, and clindamycin were determined for 307 isolates of S. pneumoniae using broth microdilution. Using serum and ELF concentrations after standard dosing, we calculated the proportion of isolates against which it would be possible to obtain a ratio of azithromycin area under the curve to MIC > or =25 and clarithromycin concentrations that exceeded the MIC for > or =40% of the dosing interval.

RESULTS

Overall, 19.5%, 25.4%, 25.1%, and 7.2% of the 307 pneumococcal isolates were resistant to penicillin, azithromycin, clarithromycin, and clindamycin, respectively. However, 71.7% of penicillin-resistant strains were also resistant to azithromycin and clarithromycin. Based on serum concentrations, clarithromycin achieved its pharmacodynamic target in 76.9% of isolates, compared with 59.9% for azithromycin. Based on ELF concentrations, clarithromycin achieved its pharmacodynamic target in 93.5% of isolates, compared with 74.6% for azithromycin. Based on ELF concentrations, clarithromycin achieved its pharmacodynamic target in 86.7% of penicillin-resistant isolates, compared with 28.3% for azithromycin.

CONCLUSIONS

On the basis of serum and ELF concentrations, clarithromycin achieved pharmacodynamic targets against a greater proportion of S. pneumoniae isolates than did azithromycin. Clinical studies are needed to determine the efficacy of these agents against pneumococci that demonstrate in vitro resistance using current susceptibility breakpoints.

Evaluation of Binax NOW, an assay for the detection of pneumococcal antigen in urine samples, performed among pediatric patients

In our evaluation of a new assay for the detection of pneumococcal antigen in urine (Binax NOW; Binax), the test result was no more likely to be positive among 88 children with radiographically confirmed pneumonia than among 198 control subjects; however, it was significantly more likely to be positive among children who were nasopharyngeal carriers of pneumococci. This test is not likely to be useful for distinguishing children with pneumococcal pneumonia from those who are merely colonized.

Effectiveness of levofloxacin for adult community-acquired pneumonia caused by macrolide-resistant Streptococcus pneumoniae: integrated results from four open-label, multicenter, phase III clinical trials

BACKGROUND

The rate of macrolide resistance among Streptococcus pneumoniae clinical isolates is rising. Coresistance to several unrelated classes of antimicrobial agents is common and may limit the treatment options available for the management of infections caused by this pathogen. Although the fluoroquinolones appear to retain activity against macrolide-resistant pneumococci, limited clinical data exist to support their use in this setting.

OBJECTIVE

This study integrated data from 4 clinical trials to determine whether the fluoroquinolone levofloxacin is an effective therapeutic agent for community-acquired pneumonia (CAP) caused by macrolide-resistant S. pneumoniae.

METHODS

Across the 4 trials, 271 adult patients with CAP were diagnosed with infections caused by S. pneumoniae; these constituted the intent-to-treat population. Clinical isolates obtained from each patient at admission were tested using broth microdilution for in vitro sensitivity to the macrolide erythromycin (minimum inhibitory concentration breakpoints: susceptible, < or =0.25 microg/mL; intermediate, 0.5 microg/mL; resistant, > or =1.0 microg/mL). All patients received levofloxacin (500 mg once daily for 7-14 days) and were analyzed at a posttherapy visit (2-5 days after completion of therapy) for clinical and microbiologic outcomes; in 3 trials, patients were also examined at a poststudy visit (14-28 days after completion of treatment). Clinical and microbiologic outcomes were analyzed in patients infected with macrolide-resistant and macrolide-susceptible S. pneumoniae.

RESULTS

A total of 235 evaluable patients infected with S. pneumoniae were identified from the 4 trials. Twenty-seven (11.5%) patients were infected with isolates resistant to erythromycin, of whom 26 (96.3%) were clinical successes. By comparison, the clinical success rate in patients infected with erythromycin-susceptible isolates was 97.7%.

CONCLUSIONS

These results suggest that if future studies demonstrate the clinical relevance of macrolide resistance, levofloxacin may be a useful therapeutic option in patients with CAP caused by macrolide-resistant S. pneumoniae. However, caution may be warranted to prevent overprescription of levofloxacin and other fluoroquinolones, given the potential for the development of resistance in S. pneumoniae.