Guidelines for Empiric Antimicrobial Prescribing in Community-Acquired Pneumonia

Outpatient management of community-acquired pneumonia

PURPOSE OF REVIEW

The first guidelines on community-acquired pneumonia (CAP) were published in 1993, but since then many of the challenges regarding the outpatient management of CAP persist. These include the difficulty in establishing the initial clinical diagnosis, its risk stratification, which will dictate the place of treatment, the empirical choice of antibiotics, the relative scarcity of novel antibiotics and the importance of knowing local microbiological susceptibility patterns.

RECENT FINDINGS

New molecular biology methods have changed the etiologic perspective of CAP, especially the contribution of virus. Lung ultrasound and biomarkers might aid diagnosis and severity stratification in the outpatient setting. Antibiotic resistance is a growing problem that reinforces the importance of novel antibiotics. And finally, prevention and the use of anti-pneumococcal vaccine are instrumental in reducing the burden of disease.

SUMMARY

Most of CAP cases are managed in the community; however, most research comes from hospitalized severe patients. New and awaited advances might contribute to aid diagnosis, cause and assessment of patients with CAP in the community. This knowledge might prove decisive in the execution of stewardship programmes that maintain current antibiotics, safeguard future ones and reinforce prevention.

Macrolide therapy for community-acquired pneumonia due to atypical pathogens: outcome assessment at an early time point

BACKGROUND

Therapy directed against atypical pathogens in patients with community-acquired pneumonia (CAP) is often recommended. This post-hoc analysis evaluated the effect of addition of a macrolide to ceftaroline fosamil or ceftriaxone treatment in atypical CAP.

METHODS

Two phase 3, double-blind, comparative safety and efficacy studies of ceftaroline fosamil vs. ceftriaxone, FOCUS 1 and FOCUS 2, enrolled adults with CAP. Only FOCUS 1 included 24-h adjunctive clarithromycin therapy for all patients on day 1. Day 4 and test-of-cure (TOC) outcomes were compared for adjunctive vs. no adjunctive therapy.

RESULTS

Of 1240 enrolled patients, 130 patients with CAP due to atypical pathogens alone were included (FOCUS 1, n = 64; FOCUS 2, n = 66). Among patients infected with Mycoplasma pneumoniae and/or Chlamydophila pneumoniae alone, a higher clinical response rate was observed with clarithromycin plus ceftaroline fosamil or ceftriaxone compared with treatment without additional clarithromycin at day 4 [38/49 (77.6%; FOCUS 1) vs. 24/43 (55.8%; FOCUS 2)], but not at the TOC assessment [42/49 (85.7%; FOCUS 1) vs. 41/43 (95.3%; FOCUS 2)]. In patients infected with Legionella pneumophila alone, a higher clinical response rate with adjunctive clarithromycin therapy was observed at the TOC assessment alone [12/12 (100%; FOCUS 1) vs. 14/19 (73.7%; FOCUS 2)]. The unadjusted odds ratio of a favourable clinical response at day 4 with adjunctive clarithromycin vs. no adjunctive clarithromycin was 2.4 (95% confidence interval 1.1-5.1; P = 0.0299) for all pathogens combined.

CONCLUSIONS

These results suggest that empirical antibiotic therapy against atypical pathogens may improve early clinical response rate. This hypothesis is best evaluated in a prospective trial.

Management of community-acquired pneumonia in an Australian regional hospital

OBJECTIVE

Current management of hospitalised patients with community-acquired pneumonia (CAP) in an Australian regional hospital in accordance with the recommended guidelines is unknown. The prescription rate of inappropriate antibiotic therapy was measured and analysed.

DESIGN

A retrospective audit, December 2012 to November 2013.

SETTING

Regional Australian hospital in North East Victoria.

INTERVENTIONS

Interventions were the average of inpatient and intensive care unit length of stay, time to first antibiotic and to first chest X-ray, days of intravenous antibiotics, and extra intravenous therapy; proportion of intensive care unit admissions, average time to first antibiotic administration, patients with failed outpatient management of CAP, initial microbiological investigations, positive investigations, predominant microbiology, antibiotic choice, and concordance with guidelines; proportion of justifiable deviation from guidelines, ratio of patients switched to oral therapy appropriately, complications during therapy, clinical failure, inpatient mortality, mortality at 30 days, mortality at 6 months, and readmission with CAP in 30 days and in 3 months.

MAIN OUTCOME MEASURES

To improve the rates of concordance with guidelines by following a specified method to rate severity of CAP, to clearly document reasons for non-concordance with guidelines, and to rationalise investigations.

RESULTS

To improve antibiotic stewardship in the management of CAP.

CONCLUSION

In an Australian regional hospital, ceftriaxone and azithromycin were the predominant combination used at 56%, demonstrating that mild CAP was frequently overtreated. Mild CAP was eight times more likely to be treated as severe CAP (odds ratio = 8.2 (95% confidence interval, 1.7-40.3) P < 0.009). There is a need for a simple yet effective strategy to be introduced to rationalise treatment and investigation of CAP in this setting.

Necrotizing pneumonia and septic shock: suspecting CA-MRSA in patients presenting to Canadian emergency departments

We report a case of fatal necrotizing pneumonia and sepsis caused by community-associated methicillin-resistantStaphylococcus aureus(CA-MRSA) in an otherwise well, 48-year-old Canadian man with type 2 diabetes mellitus who had travelled to Texas. Despite therapy that included intravenous antibiotics, intravenous immune globulin and other supportive measures, the patient succumbed to his illness. Recently, CA-MRSA pneumonia has been reported in several countries. The virulence of this organism may in part be related to its ability to produce toxins, such as Panton-Valentine leukocidin. As rates of CA-MRSA increase worldwide, physicians should be aware of the potential for MRSA to cause life-threatening infections in patients presenting to Canadian emergency departments (EDs). Necrotizing pneumonia caused by MRSA must be considered in the differential diagnosis of acute, severe respiratory illness. Early recognition of this syndrome in the ED may help physicians initiate appropriate antibiotic therapy in a timely manner.

Adherence with national guidelines in hospitalized patients with community-acquired pneumonia: results from the CAPO study in Venezuela

INTRODUCTION

The Community-Acquired Pneumonia Organization (CAPO) is an international observational study in 130 hospitals, with a total of 31 countries, to assess the current management of hospitalized patients with community-acquired pneumonia (CAP). 2 Using the centralized database of CAPO was decided to conduct this study with the aim of evaluate the level of adherence with national guidelines in Venezuela, to define in which areas an intervention may be necessary to improve the quality of care of hospitalized patients with CAP.

METHODS

In this observational retrospective study quality indicators were used to evaluate the management of hospitalized patients with CAP in 8 Venezuelan's centers. The care of the patients was evaluated in the areas of: hospitalization, oxygen therapy, empiric antibiotic therapy, switch therapy, etiological studies, blood cultures indication, and prevention. The compliance was rated as good (>90%), intermediate (60% to 90%), or low (<60%).

RESULTS

A total of 454 patients with CAP were enrolled. The empiric treatment administered within 8 hours of the patient arrival to the hospital was good (96%), but the rest of the indicators showed a low level of adherence (<60%).

CONCLUSION

We can say that there are many areas in the management of CAP in Venezuela that are not performed according to the national guidelines of SOVETHORAX.1 In any quality improvement process the first step is to evaluate the difference between what is recommended and what is done in clinical practice. While this study meets this first step, the challenge for the future is to implement the processes necessary to improve the management of CAP in Venezuela.

Antimicrobial resistance trends among community-acquired respiratory tract pathogens in Greece, 2009-2012

The aim of the present study was to determine the antimicrobial resistance trends of respiratory tract pathogens isolated from patients with community-acquired respiratory tract infections (CARTIs) in Crete, Greece, over a 4-year period (2009-2012). A total of 588 community-acquired respiratory pathogens were isolated during the study period. Streptococcus pneumoniae was the most common organism responsible for 44.4% of CARTIs, followed by Haemophilus influenzae (44.2%) and Moraxella catarrhalis (11.4%). Among S. pneumoniae, the prevalence of isolates with intermediate- and high-level resistance to penicillin was 27.2% and 12.3%, respectively. Macrolide resistance slightly decreased from 29.4% over the period 2009-2010 to 28.8% over the period 2011-2012. Multiresistance was observed among 56 (54.4%) penicillin nonsusceptible isolates. A nonsignificant increase in resistance of H. influenzae isolates was noted for β -lactams, cotrimoxazole, and tetracycline. Among the 67 M. catarrhalis tested, 32 produced beta-lactamase and were resistant to ampicillin. Macrolide resistance decreased over the study period. All isolates were susceptible to amoxicillin + clavulanic acid, chloramphenicol, rifampicin, and the fluoroquinolones. Although a decreasing trend in the prevalence of resistance of the three most common pathogens involved in CARTIs was noted, continuous surveillance of antimicrobial susceptibility at the local and national level remains important, in order to guide appropriate empirical antimicrobial therapy.

Extended release amoxicillin/clavulanate: optimizing a product for respiratory infections based on pharmacodynamic principles

Acute bacterial respiratory tract infections cause a great deal of human morbidity and mortality. Treatment guidelines for these infections include macrolides, doxycycline, beta-lactams and beta-lactam/beta-lactamase inhibitor combinations such as amoxicillin/clavulanic acid to provide coverage for the common respiratory pathogens, including penicillin and macrolide nonsusceptible Streptococcus pneumoniae, as well as beta-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis. In response to recent guidelines recommending higher dose amoxicillin to extend coverage to a higher percentage of S. pneumoniae, a new formulation of amoxicillin/clavulanic acid was developed. This formulation includes a higher amoxicillin dose, with part of the amoxicillin dose being in an extended release formulation, without increasing the clavulanate dose, for twice-daily oral treatment of these infections. Clinical studies of community-acquired pneumonia and acute rhinosinusitis have shown that the new formulation is well tolerated and highly efficacious, with clinical outcomes equivalent to comparators.

Hospital-based strategies to reduce antibiotic resistance: are they valid in the community setting?

Antimicrobial resistance is an increasing problem worldwide in both the hospital and community settings. Various approaches have been proposed and tested mainly in the hospital environment to reduce this problem; however, few of these have been examined from the perspective of applicability to reversing community-based resistance. It is clear that, in addition to specific antibiotic usage campaigns, a major educational initiative for both prescribers and patients alike is required for the full societal impact of growing antibiotic resistance to be appreciated. This inexorable increase is occurring in the face of a dearth of new antibiotics for community use and even fewer for treating resistant nosocomial gram-negative species. The possible strategies and consequences are discussed.

Does empiric therapy for atypical pathogens improve outcomes for patients with CAP?

The present controversy regarding the need to cover atypical pathogens in the empiric therapy of community-acquired pneumonia is related to several issues, including the relevance of terminology, imprecise diagnostic methods, and perceived contradictory results of published evidence. Studies evaluating the time to clinical recovery and the use of earlier endpoints for evaluation suggest that appropriate therapy provides a benefit if an atypical pathogen is a pathogen. Because recent surveillance studies suggest these pathogens are common and until there is the availability of accurate, cost-effective, and easily interpreted laboratory tests to provide the etiologic diagnosis at the time of point of care, empiric therapy of atypical pathogens is supported.

Randomized, double-blind, multicenter phase 2 study comparing the efficacy and safety of oral solithromycin (CEM-101) to those of oral levofloxacin in the treatment of patients with community-acquired bacterial pneumonia

Solithromycin, a new macrolide, and the first fluoroketolide in clinical development, with activity against macrolide-resistant bacteria, was tested in 132 patients with moderate to moderately severe community-acquired bacterial pneumonia (CABP) in a multicenter, double-blind, randomized phase 2 study. Patients were enrolled and randomized (1:1) to either 800 mg solithromycin orally (PO) on day 1, followed by 400 mg PO daily on days 2 to 5, or 750 mg levofloxacin PO daily on days 1 to 5. Efficacy outcome rates of clinical success at the test-of-cure visit 4 to 11 days after the last dose of study drug were comparable in the intent-to-treat (ITT) (84.6% for solithromycin versus 86.6% for levofloxacin) and microbiological-intent-to-treat (micro-ITT) (77.8% for solithromycin versus 71.4% for levofloxacin) populations. Early response success rates at day 3, defined as improvement in at least two cardinal symptoms of pneumonia, were also comparable (72.3% for solithromycin versus 71.6% for levofloxacin). More patients treated with levofloxacin than with solithromycin experienced treatment-emergent adverse events (TEAEs) during the study (45.6% versus 29.7%). The majority of TEAEs were mild or moderate gastrointestinal symptoms and included nausea (1.6% for solithromycin; 10.3% for levofloxacin), diarrhea (7.8% for solithromycin; 5.9% for levofloxacin), and vomiting (0% for solithromycin; 4.4% for levofloxacin). Six patients, all of whom received levofloxacin, discontinued the study drug due to an adverse event. Solithromycin demonstrated comparable efficacy and favorable safety relative to levofloxacin. These findings support a phase 3 study of solithromycin for the treatment of CABP. (This study has been registered at ClinicalTrials.gov under registration no. NCT01168713.).

Tigecycline versus levofloxacin in hospitalized patients with community-acquired pneumonia: an analysis of risk factors

INTRODUCTION

This study was conducted to evaluate the efficacy of tigecycline (TGC) versus levofloxacin (LEV) in hospitalized patients with community-acquired pneumonia (CAP) using pooled data and to perform exploratory analyses of risk factors associated with poor outcome.

MATERIALS AND METHODOLOGY

Pooled analyses of 2 phase 3 studies in patients randomized to intravenous (IV) TGC (100 mg, then 50 mg q12h) or IV LEV (500 mg q24h or q12h). Clinical responses at test of cure visit for the clinically evaluable (CE) and clinical modified intention to treat populations were assessed for patients with risk factors including aged ≥65 years, prior antibiotic failure, bacteremia, multilobar disease, chronic obstructive pulmonary disease, alcohol abuse, altered mental status, hypoxemia, renal insufficiency, diabetes mellitus, white blood cell count >30 x 10(9)/L or <4 x 10(9)/L, CURB-65 score ≥2, Fine score category of III to V and at least 2 clinical instability criteria on physical examination.

RESULTS

In the CE population of 574 patients, overall cure rates were similar: TGC (253/282, 89.7%); LEV (252/292, 86.3%). For all but one risk factor, cure rates for TGC were similar to or higher than those for LEV. For individual risk factors, the greatest difference between treatment groups was observed in patients with diabetes mellitus (difference of 22.9 for TGC versus LEV; 95% confidence interval, 4.8 - 39.9).

CONCLUSIONS

TGC achieved cure rates similar to those of LEV in hospitalized patients with CAP. For patients with risk factors, TGC provided generally favorable clinical outcomes.

High-dose levofloxacin in community-acquired pneumonia: a randomized, open-label study

BACKGROUND

The conventional treatment for community-acquired pneumonia (CAP) involves combination therapy consisting of a β-lactam penicillin or a cephalosporin with a macrolide. Alternatively, high-dose levofloxacin treatment has been used as single-agent therapy for treating CAP, covering atypical pathogens.

OBJECTIVE

This study compared the clinical efficacy and safety of high-dose levofloxacin with combined ceftriaxone and azithromycin for the treatment of CAP.

PATIENTS AND METHODS

This phase IV, prospective, randomized, open-label trial enrolled patients admitted to a tertiary referral hospital for CAP treatment from 2010 to 2011. Hospital admission was decided based on clinical judgement and the pneumonia severity index. Forty subjects were enrolled and assigned to two treatment arms using a random numbers table. The 20 subjects in the experimental group were given levofloxacin 750 mg intravenously once daily, followed by the same dose of oral levofloxacin at discharge when clinically improved and the 20 subjects in the control group were given ceftriaxone 2.0 g intravenously once daily plus oral azithromycin 500 mg for 3 consecutive days, followed by oral cefpodoxime 200 mg per day at discharge after clinical improvement. The primary outcome was the clinical success rate. Secondary outcomes were the microbiological success rate and adverse events during the study.

RESULTS

Of the 40 subjects enrolled, 36 completed the study: 17 in the experimental group and 19 in the control group. The groups did not differ in terms of demographic factors or clinical findings at baseline. The clinical success rate (cured + improved) was 94% in the experimental (levofloxacin) group and 84% in the control group (p > 0.05). The microbiological success rate and overall adverse events were also similar in both groups.

CONCLUSION

Single-agent, high-dose levofloxacin treatment exhibited excellent clinical and microbiological efficacy with a safety profile comparable to that of ceftriaxone plus azithromycin therapy. Large-scale clinical trials are required to verify these results.

CLINICAL TRIAL REGISTRATION

WHO International Clinical Trials Registry: KCT0000374; Daiichi-Sankyo Korea study code: T11-13-V1.

High-dose levofloxacin in community-acquired pneumonia: a randomized, open-label study

BACKGROUND

The conventional treatment for community-acquired pneumonia (CAP) involves combination therapy consisting of a β-lactam penicillin or a cephalosporin with a macrolide. Alternatively, high-dose levofloxacin treatment has been used as single-agent therapy for treating CAP, covering atypical pathogens.

OBJECTIVE

This study compared the clinical efficacy and safety of high-dose levofloxacin with combined ceftriaxone and azithromycin for the treatment of CAP.

PATIENTS AND METHODS

This phase IV, prospective, randomized, open-label trial enrolled patients admitted to a tertiary referral hospital for CAP treatment from 2010 to 2011. Hospital admission was decided based on clinical judgement and the pneumonia severity index. Forty subjects were enrolled and assigned to two treatment arms using a random numbers table. The 20 subjects in the experimental group were given levofloxacin 750 mg intravenously once daily, followed by the same dose of oral levofloxacin at discharge when clinically improved and the 20 subjects in the control group were given ceftriaxone 2.0 g intravenously once daily plus oral azithromycin 500 mg for 3 consecutive days, followed by oral cefpodoxime 200 mg per day at discharge after clinical improvement. The primary outcome was the clinical success rate. Secondary outcomes were the microbiological success rate and adverse events during the study.

RESULTS

Of the 40 subjects enrolled, 36 completed the study: 17 in the experimental group and 19 in the control group. The groups did not differ in terms of demographic factors or clinical findings at baseline. The clinical success rate (cured + improved) was 94% in the experimental (levofloxacin) group and 84% in the control group (p > 0.05). The microbiological success rate and overall adverse events were also similar in both groups.

CONCLUSION

Single-agent, high-dose levofloxacin treatment exhibited excellent clinical and microbiological efficacy with a safety profile comparable to that of ceftriaxone plus azithromycin therapy. Large-scale clinical trials are required to verify these results.

CLINICAL TRIAL REGISTRATION

WHO International Clinical Trials Registry: KCT0000374; Daiichi-Sankyo Korea study code: T11-13-V1.

Cethromycin versus clarithromycin for community-acquired pneumonia: comparative efficacy and safety outcomes from two double-blinded, randomized, parallel-group, multicenter, multinational noninferiority studies

Community-acquired pneumonia (CAP) continues to be a major health challenge in the United States and globally. Factors such as overprescribing of antibiotics and noncompliance with dosing regimens have added to the growing antibacterial resistance problem. In addition, several agents available for the treatment of CAP have been associated with serious side effects. Cethromycin is a new ketolide antibiotic that may provide prescribing physicians with an additional agent to supplement a continually limited armamentarium. Two global phase III noninferiority studies (CL05-001 and CL06-001) to evaluate cethromycin safety and efficacy were designed and conducted in patients with mild to moderate CAP. Study CL05-001 demonstrated an 83.1% clinical cure rate in the cethromycin group compared with 81.1% in the clarithromycin group (95% confidence interval [CI], -4.8%, +8.9%) in the intent to treat (ITT) population and a 94.0% cethromycin clinical cure rate compared with a 93.8% clarithromycin cure rate (95% CI, -4.5%, +5.1%) in the per protocol clinical (PPc) population. Study CL06-001 achieved an 82.9% cethromycin clinical cure rate in the ITT population compared with an 88.5% clarithromycin cure rate (95% CI, -11.9%, +0.6%), whereas the clinical cure rate in the PPc population was 91.5% in cethromycin group compared with 95.9% in clarithromycin group (95% CI, -9.1%, +0.3%). Both studies met the primary endpoints for clinical cure rate based on predefined, sliding-scale noninferiority design. Therefore, in comparison with clarithromycin, these two noninferiority studies demonstrated the efficacy and safety of cethromycin, with encouraging findings of efficacy in subjects with Streptococcus pneumoniae bacteremia. No clinically significant adverse events were observed during the studies. Cethromycin may be a potential oral therapy for the outpatient treatment of CAP.

Cumulative clinical experience from over a decade of use of levofloxacin in community-acquired pneumonia: critical appraisal and role in therapy

Levofloxacin is the synthetic L-isomer of the racemic fluoroquinolone, ofloxacin. It interferes with critical processes in the bacterial cell such as DNA replication, transcription, repair, and recombination by inhibiting bacterial topoisomerases. Levofloxacin has broad spectrum activity against several causative bacterial pathogens of community-acquired pneumonia (CAP). Oral levofloxacin is rapidly absorbed and is bioequivalent to the intravenous formulation such that patients can be conveniently transitioned between these formulations when moving from the inpatient to the outpatient setting. Furthermore, levofloxacin demonstrates excellent safety, and has good tissue penetration maintaining adequate concentrations at the site of infection. The efficacy and tolerability of levofloxacin 500 mg once daily for 10 days in patients with CAP are well established. Furthermore, a high-dose (750 mg) and short-course (5 days) of once-daily levofloxacin has been approved for use in the US in the treatment of CAP, acute bacterial sinusitis, acute pyelonephritis, and complicated urinary tract infections. The high-dose, short-course levofloxacin regimen maximizes its concentration-dependent antibacterial activity, decreases the potential for drug resistance, and has better patient compliance.

Levofloxacin in the treatment of community-acquired pneumonia

Levofloxacin is a fluoroquinolone that has a broad spectrum of activity against several causative bacterial pathogens of community-acquired pneumonia (CAP). The efficacy and tolerability of levofloxacin 500 mg once daily for 10 days in patients with CAP are well established. Furthermore, a high-dose (750 mg), short-course (5 days) of once-daily levofloxacin has been approved for use in the USA in the treatment of CAP, acute bacterial sinusitis, acute pyelonephritis and complicated urinary tract infections. Levofloxacin can be used as a monotherapy in patients with CAP, however, levofloxacin combination therapy with anti-pseudomonal beta-lactam (or aminoglycoside) should be considered if Pseudomonas aeruginosa is the causative pathogen of the respiratory infection. The high-dose, short-course levofloxacin regimen maximizes its concentration-dependent antibacterial activity, decreases the potential for drug resistance and has better patient compliance. Oral levofloxacin is rapidly absorbed and is bioequivalent to the intravenous formulation and the patients can switch between these formulations, which results in more options with respect to the therapeutic regimens. Furthermore, levofloxacin is generally well tolerated, has good tissue penetration and adequate concentrations can be maintained at the site of infections.

[Community-acquired pneumonia: a 7-years descriptive study. Usefulness of the IDSA/ATS 2007 in the assessment of ICU admission]

OBJECTIVE

To describe the clinical characteristics and outcomes of patients with community-acquired pneumonia (CAP) admitted to the Intensive Care Unit (ICU). To evaluate new ATS/IDSA criteria to identify patients with CAP who required admission to ICU.

DESIGN

Retrospective analysis of prospective collected data in a 7-year period (2000-2007).

SETTING

Medical-surgical ICU with 16 beds.

PATIENTS

All patients with severe CAP admitted to the ICU (n=147). PRIMARY ENDPOINTS: Clinical and microbiological characteristics. Prognostic factors. Comparison of patients admitted in the ICU and ATS/IDSA criteria (group 1: > or = 1 major criterion, group 2: > or = 3 minor criteria and group 3: no criterion).

INTERVENTION

None.

RESULTS

Admission to the ICU is required for patients with acute respiratory failure (60.5%) and with septic shock (28.5%). A total of 71.4%, had an identifiable microbial etiology, S. pneumoniae being the most frequently isolated. Mean time to antibiotic therapy was 4.3+/-4.2h, this being adequate in 97.1%. ICU global mortality rate was 32%. Prognostic factors associated with higher mortality were acute renal failure (OR:4.7), mechanical ventilation (OR:3.4), non-identifiable etiology (OR:4.2) and non-S. pneumonia etiology (OR:3.5). Sixty-eight percent of the patients were included in the first group of the ATS/IDSA criteria and 21% in the second group.

CONCLUSIONS

CAP mortality is still high despite early antibiotic therapy, especially in those patients with a non-S. pneumonia etiology or who require mechanical ventilation. Almost 90% of the ICU admissions were identified by the new criteria from ATS/IDSA.

Efficacy and safety of tigecycline versus levofloxacin for community-acquired pneumonia

BACKGROUND

Tigecycline, an expanded broad-spectrum glycylcycline, exhibits in vitro activity against many common pathogens associated with community-acquired pneumonia (CAP), as well as penetration into lung tissues that suggests effectiveness in hospitalized CAP patients. The aim of the present study was to compare the efficacy and safety of intravenous (IV) tigecycline with IV levofloxacin in hospitalized adults with CAP.

METHODS

In this prospective, double-blind, non-inferiority phase 3 trial, eligible patients with a clinical diagnosis of CAP supported by radiographic evidence were stratified by Fine Pneumonia Severity Index and randomized to tigecycline or levofloxacin for 7-14 days of therapy. Co-primary efficacy endpoints were clinical response in the clinically evaluable (CE) and clinical modified intent-to-treat (c-mITT) populations at test-of-cure (Day 10-21 post-therapy).

RESULTS

Of the 428 patients who received at least one dose of study drug, 79% had CAP of mild-moderate severity according to their Fine score. Clinical cure rates for the CE population were 88.9% for tigecycline and 85.3% for levofloxacin. Corresponding c-mITT population rates were 83.7% and 81.5%, respectively. Eradication rates for Streptococcus pneumoniae were 92% for tigecycline and 89% for levofloxacin. Nausea, vomiting, and diarrhoea were the most frequently reported adverse events. Rates of premature discontinuation of study drug or study withdrawal because of any adverse event were similar for both study drugs.

CONCLUSION

These findings suggest that IV tigecycline is non-inferior to IV levofloxacin and is generally well-tolerated in the treatment of hospitalized adults with CAP.

TRIAL REGISTRATION

NCT00081575.

What can we learn from the time course of untreated and partially treated community-onset Streptococcus pneumoniae pneumonia? A clinical perspective on superiority and noninferiority trial designs for mild community-acquired pneumonia

There are no well-designed placebo-controlled clinical trials in the recent era that precisely define the magnitude of the drug effect of antimicrobial therapy for mild community-acquired pneumonia (CAP). However, there is evidence that ineffective therapies, selected on the basis of the ratio of 24-h area under the concentration curve to minimum inhibitory concentration, associated with a discordant (nonsusceptible in vitro) specific agent (or no therapy) for mild CAP due to Streptococcus pneumoniae are associated with increased risk of progression to serious CAP. The relatively high rate of clinical success associated with appropriate antimicrobial treatment of mild CAP renders a standard outcome measure of clinical success an unlikely way to differentiate new agents. However, there may be an advantage in composite outcome assessments for mild CAP. Composite-outcomes end points that include time to resolution of morbidity, the use of patient reported-outcomes instruments, and biomarkers are recommended for future studies. Because the composite rate of success in recent randomized clinical trials exceeds 90%, it would seem that a noninferiority margin of 10% is reasonable for trials for mild CAP.

Integrated results of 2 phase 3 studies comparing tigecycline and levofloxacin in community-acquired pneumonia

Tigecycline (TGC), a glycylcycline, has expanded activity against Gram-positive and Gram-negative, anaerobic, and atypical bacteria. Two phase 3 studies were conducted. Hospitalized patients with community-acquired pneumonia (CAP) were randomized to intravenous (IV) TGC (100 mg followed by 50 mg bid) or IV levofloxacin (LEV) (500 mg bid). In 1 study, patients could be switched to oral LEV after at least 3 days intravenously. The coprimary efficacy end points were as follows: clinical response in clinically evaluable (CE) and clinical modified intent-to-treat (c-mITT) populations at test-of-cure (TOC). The secondary end points were as follows: microbiologic efficacy and susceptibility to TGC for CAP bacteria. Safety evaluations were included. Eight hundred ninety-one were patients screened: 846 mITT (TGC 424, LEV 422), 574 CE (TGC 282, LEV 292). Most patients had Fine Pneumonia Severity Index II to IV (80.7% TGC, 74.4% LEV, mITT). At TOC (CE), TGC cured 253/282 patients (89.7%) and LEV cured 252/292 patients (86.3%); the absolute difference of TGC-LEV was 3.4% (95% confidence interval [CI], -2.2 to 9.1, noninferior [P < 0.001]). In c-mITT, TGC cured 319/394 patients (81.0%) and LEV cured 321/403 patients (79.7%); the absolute difference of TGC-LEV was 1.3% (95% CI -4.5 to 7.1, noninferior [P < 0.001]). The drug-related adverse events (AEs) of nausea (20.8% TGC versus 6.6% LEV) and vomiting (13.2% TGC versus 3.3% LEV) were significantly higher in TGC; elevated alanine aminotransferase (2.8% TGC versus 7.3% LEV) and aspartate aminotransferase (2.6% TGC versus 6.9% LEV) were significantly higher in LEV. Discontinuations for AEs were low (TGC, 26 patients [6.1%]; LEV, 34 patients [8.1%]). TGC appeared safe and achieved cure rates similar to LEV in hospitalized patients with CAP.

Efficacy of short-course antibiotic regimens for community-acquired pneumonia: a meta-analysis

PURPOSE

There is little consensus on the most appropriate duration of antibiotic treatment for community-acquired pneumonia. The goal of this study is to systematically review randomized controlled trials comparing short-course and extended-course antibiotic regimens for community-acquired pneumonia.

METHODS

We searched MEDLINE, Embase, and CENTRAL, and reviewed reference lists from 1980 through June 2006. Studies were included if they were randomized controlled trials that compared short-course (7 days or less) versus extended-course (>7 days) antibiotic monotherapy for community-acquired pneumonia in adults. The primary outcome measure was failure to achieve clinical improvement.

RESULTS

We found 15 randomized controlled trials matching our inclusion and exclusion criteria comprising 2796 total subjects. Short-course regimens primarily studied the use of azithromycin (n=10), but trials examining beta-lactams (n=2), fluoroquinolones (n=2), and ketolides (n=1) were found as well. Of the extended-course regimens, 3 studies utilized the same antibiotic, whereas 9 involved an antibiotic of the same class. Overall, there was no difference in the risk of clinical failure between the short-course and extended-course regimens (0.89, 95% confidence interval [CI], 0.78-1.02). In addition, there were no differences in the risk of mortality (0.81, 95% CI, 0.46-1.43) or bacteriologic eradication (1.11, 95% CI, 0.76-1.62). In subgroup analyses, there was a trend toward favorable clinical efficacy for the short-course regimens in all antibiotic classes (range of relative risk, 0.88-0.94).

CONCLUSIONS

The available studies suggest that adults with mild to moderate community-acquired pneumonia can be safely and effectively treated with an antibiotic regimen of 7 days or less. Reduction in patient exposure to antibiotics may limit the increasing rates of antimicrobial drug resistance, decrease cost, and improve patient adherence and tolerability.

Antibiotic treatment of community acquired pneumonia varies widely across Germany

Community Acquired Pneumonia (CAP) is a frequent and potentially fatal infectious disease which, in the majority of cases, needs an antibiotic intervention.

OBJECTIVES

Aim was to evaluate antibiotic treatment patterns regarding all types of mono- and combination-therapy throughout the local clinical centres (LCCs) represented in the German competence network CAPNETZ (=Community Acquired Pneumonia Network) and to identify clinical indicators for regional differences.

METHODS

We analysed outpatients and inpatients recruited between March 2003 and April 2005. Patient and treatment details were registered online using standardised data entry forms. A logistic regression model was issued for the 4 most frequently applied antibiotics, adjusting for potentially relevant confounders.

RESULTS

The study sample consisted of 3221 patients at the age of 18 to 102 years. Overall, aminopenicillins plus betalactamase inhibitor (20.4%), fluoroquinolone (17.0%), macrolides combined with cephalosporins third generation (10.6%) and cephalosporins third generation (8.9%) were most frequently prescribed. After control for potential confounders, significant treatment differences remained between study sites. Regional variability of antibiotic CAP-treatment could not be attributed to a number of clinical or sociodemographic factors.

CONCLUSIONS

The presented treatment variability ranges within given guidelines, but indicates the need for an ongoing implementation of evidence-based guidelines in order to avoid potential negative clinical or economic consequences.

Activity of garenoxacin, an investigational des-F(6)-quinolone, tested against pathogens from community-acquired respiratory tract infections, including those with elevated or resistant-level fluoroquinolone MIC values

Garenoxacin, a novel des-F(6)-quinolone, was tested against 40423 pathogenic isolates associated with community-acquired respiratory tract infections (CA-RTIs). The strains included Streptococcus pneumoniae (18887), Haemophilus influenzae (15555), and Moraxella catarrhalis (5981), each isolated from a significant infection monitored by the SENTRY Antimicrobial Surveillance Program (1999-2005; North America, Latin America, and Europe). All tests were performed by reference broth microdilution methods for garenoxacin and 19 comparison agents. The garenoxacin MIC(90) and percentage (%) of strains inhibited at < or =1 microg/mL (proposed susceptible breakpoint) were S. pneumoniae (0.06 microg/mL, >99.9% susceptible), H. influenzae (< or =0.03 microg/mL, >99.9%), and M. catarrhalis (< or =0.03 microg/mL, 100.0%). The garenoxacin potency versus the pneumococci was 16- to 32-fold greater than levofloxacin or ciprofloxacin and 2-fold superior to moxifloxacin (MIC(90), 0.12 microg/mL). Resistances to other classes of antimicrobials did not adversely influence garenoxacin MIC results. Ciprofloxacin- or levofloxacin-resistant (MIC, > or =4 microg/mL) S. pneumoniae had higher garenoxacin MIC(90) values (1 microg/mL), but 90.6% to 97.5% of strains remained susceptible. Strains of all 3 monitored pathogens with mutations in the quinolone resistance determining region (QRDR) had higher garenoxacin MIC results, with > or =3 to 4 QRDR mutations required to elevate garenoxacin MIC values to > or =2 microg/mL. In conclusion, garenoxacin possesses a potent activity against pneumococci, H. influenzae, and M. catarrhalis strains worldwide, at a level significantly greater than the available tested agents in the fluoroquinolone class (ciprofloxacin, levofloxacin, and moxifloxacin). Only 13 and 4 isolates (0.07% and 0.03%) of S. pneumoniae and H. influenzae, respectively, had a garenoxacin MIC at > or =2 microg/mL, thus, making this new "respiratory antipneumococcal" quinolone an attractive candidate for the therapy of contemporary CA-RTI (bronchitis, pneumonia, and sinusitis).

Garenoxacin activity against isolates form patients hospitalized with community-acquired pneumonia and multidrug-resistant Streptococcus pneumoniae

Community-acquired pneumonia (CAP) continues to cause significant morbidity worldwide, and the principal bacterial pathogens (Streptococcus pneumoniae and Haemophilus influenzae) have acquired numerous resistance mechanisms over the last few decades. CAP treatment guidelines have suggested the use of broader spectrum agents, such as antipneumococcal fluoroquinolones as the therapy for at-risk patient population. In this report, we studied 3087 CAP isolates from the SENTRY Antimicrobial Surveillance Program (1999-2005) worldwide and all respiratory tract infection (RTI) isolate population of pneumococci (14665 strains) grouped by antibiogram patterns against a new des-F(6)-quinolone, garenoxacin. Results indicated that garenoxacin was highly active against CAP isolates of S. pneumoniae (MIC(90), 0.06 microg/mL) and H. influenzae (MIC(90), < or =0.03 microg/mL). This garenoxacin potency was 8- to 32-fold greater than gatifloxacin, levofloxacin, and ciprofloxacin against the pneumococci and >99.9% of strains were inhibited at < or =1 microg/mL (proposed susceptible breakpoint). Garenoxacin MIC values were not affected by resistances among S. pneumoniae strains to penicillin or erythromycin; however, coresistances were high among the beta-lactams (penicillins and cephalosporins), macrolides, tetracyclines, and trimethoprim/sulfamethoxazole. Analysis of S. pneumoniae isolates with various antimicrobial resistance patterns to 6 drug classes demonstrated that garenoxacin was active against >99.9% (MIC, < or =1 microg/mL) of strains, and the most resistant pneumococci (6-drug resistance, 1051 strains or 7.2% of all isolates) were completely susceptible (100.0% at < or =1 microg/mL) to garenoxacin (MIC(90), 0.06 microg/mL). These results illustrate the high activity of garenoxacin against contemporary CAP isolates and especially against multidrug-resistant (MDR) S. pneumoniae that have created therapeutic dilemmas for all RTI presentations. Garenoxacin appears to be a welcome addition to the CAP treatment options, particularly for the emerging MDR pneumococci strains.

Clinical and bacteriological outcomes in hospitalised patients with community-acquired pneumonia treated with azithromycin plus ceftriaxone, or ceftriaxone plus clarithromycin or erythromycin: a prospective, randomised, multicentre study

This study compared patients with moderate-to-severe community-acquired pneumonia (CAP) requiring hospitalisation, who received initial therapy with either intravenous ceftriaxone plus intravenous azithromycin, followed by step-down to oral azithromycin (n = 135), with patients who received intravenous ceftriaxone combined with either intravenous clarithromycin or erythromycin, followed by step-down to either oral clarithromycin or erythromycin (n = 143). Clinical and bacteriological outcomes were evaluated at the end of therapy (EOT; day 12-16) or at the end of study (EOS; day 28-35). At baseline, mean APACHE II scores were 13.3 and 12.6, respectively, with >50% of patients classified as Fine Pneumonia Severity Index (PSI) category IV or V. Clinical success rates (cure or improvement) in the modified intent-to-treat (MITT) population at EOT were 84.3% in the ceftriaxone/azithromycin group and 82.7% in the ceftriaxone/clarithromycin or erythromycin group. At EOS, MITT success rates (cure only) were 81.7% and 75.0%, respectively. Equivalent success rates in the clinically evaluable population were 83% and 87%, respectively, at EOT, and 79% and 78%, respectively, at EOS. MITT bacteriological eradication rates were 73.2% and 67.4%, respectively, at EOT, and 68.3% vs. 60.9%, respectively, at EOS. Mean length of hospital stay (LOS) was 10.7 and 12.6 days, and the mean duration of therapy was 9.5 and 10.5 days, respectively. The incidence of infusion-related adverse events was 16.3% and 25.2% (p 0.04), respectively. An intravenous-to-oral regimen of ceftriaxone/azithromycin was at least equivalent in efficacy and safety to the comparator regimen and appeared to be a suitable treatment option for hospitalised patients with CAP.

Clinical implications of macrolide resistance in community-acquired respiratory tract infections

Laboratory surveillance data suggest that macrolide resistance among Streptococcus pneumoniae has increased dramatically over the past 15 years. This review examines the specifics of macrolide resistance and the clinical relevance of in vitro susceptibility testing in light of the pharmacokinetics and pharmacodynamics of azithromycin and clarithromycin. These drugs concentrate extensively within respiratory tissue and have other positive characteristics not reflected by in vitro susceptibility testing. In general, clarithromycin is the most potent macrolide and the one most likely to maintain clinical efficacy against the low-level resistance associated with most macrolide-resistant pneumococci in the USA. These findings suggest that susceptibility data may underestimate clinical utility and that clarithromycin still has a place in the empiric treatment of respiratory infections.

Clinical impact of antibiotic resistance in respiratory tract infections

Streptococcus pneumoniae is the most common causative pathogen of community-acquired respiratory tract infections. In vitro evidence indicates that S. pneumoniae is increasingly resistant to commonly prescribed antimicrobial agents including the macrolides. The clinical relevance of resistance, however, has not been clearly established. This article reviews the risk factors influencing selection of resistant pneumococci, discusses endpoints used to assess the impact of resistance on clinical outcome, and proposes strategies to minimise the impact of resistance. Evidence demonstrating treatment failures due to macrolide-resistant S. pneumoniae is also reviewed. Increasing rates of resistance among S. pneumoniae present numerous clinical challenges, and require carefully selected treatment strategies to preserve antibacterial efficacy. Antibiotics with a low propensity for stimulating resistance should be chosen wherever possible.

Recent findings from multinational resistance surveys: are we ‘PROTEKTed’ from resistance?

Continual monitoring of antimicrobial resistance rates is essential. Several large surveillance programmes have been established, including the international, longitudinal, multi-centre study PROTEKT (Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin). Initiated in 1999, PROTEKT monitors the antibacterial susceptibility of common respiratory tract pathogens. This article reviews the findings from PROTEKT to date and anticipates future trends in antimicrobial resistance. Data from PROTEKT indicate that resistance patterns for Streptococcus pneumoniae and Haemophilus influenzae are changing, with an increasing prevalence of multi-drug resistant genotypes. Resistance to the ketolide telithromycin is very rare, with rates of S. pneumoniae susceptibility remaining >99%. The in vitro activity of telithromycin remains at a high level irrespective of pathogen genotype or phenotype.

Amoxicillin is effective against penicillin-resistant Streptococcus pneumoniae strains in a mouse pneumonia model simulating human pharmacokinetics

High-dose oral amoxicillin (3 g/day) is the recommended empirical outpatient treatment of community-acquired pneumonia (CAP) in many European guidelines. To investigate the clinical efficacy of this treatment in CAP caused by Streptococcus pneumoniae strains with MICs of amoxicillin > or =2 microg/ml, we used a lethal bacteremic pneumonia model in leukopenic female Swiss mice with induced renal failure to replicate amoxicillin kinetics in humans given 1 g/8 h orally. Amoxicillin (15 mg/kg of body weight/8 h subcutaneously) was given for 3 days. We used four S. pneumoniae strains with differing amoxicillin susceptibility and tolerance profiles. Rapid bacterial killing occurred with an amoxicillin-susceptible nontolerant strain: after 4 h, blood cultures were negative and lung homogenate counts under the 2 log(10) CFU/ml detection threshold (6.5 log(10) CFU/ml in controls, P < 0.01). With an amoxicillin-intermediate nontolerant strain, significant pulmonary bacterial clearance was observed after 24 h (4.3 versus 7.9 log(10) CFU/ml, P < 0.01), and counts were undetectable 12 h after treatment completion. With an amoxicillin-intermediate tolerant strain, 24-h bacterial clearance was similar (5.4 versus 8.3 log(10) CFU/ml, P < 0.05), but 12 h after treatment completion, lung homogenates contained 3.3 log(10) CFU/ml. Similar results were obtained with an amoxicillin-resistant and -tolerant strain. Day 10 survival rates were usually similar across strains. Amoxicillin with pharmacokinetics simulating 1 g/8 h orally in humans is bactericidal in mice with pneumonia due to S. pneumoniae for which MICs were 2 to 4 microg/ml. The killing rate depends not only on resistance but also on tolerance of the S. pneumoniae strains.

Antibiothérapie des pneumonies aiguës communautaires à Streptococcus pneumoniae : impact clinique de la résistance bactérienne

The emergence of Streptococcus pneumoniae strains with reduced susceptibility to beta-lactams and with multiple drug resistance has not led to major changes in recommendations for antibiotic therapy in patients with acute community-acquired pneumococcal pneumonia. Numerous factors explain the limited clinical impact of this major microbiological change. The frequency of intermediate strains is high but the frequency of resistant strains to beta-lactams is very low. There is a complex relation between the acquisition of resistance to beta-lactams and the decreased virulence of S. pneumoniae strains. The only finding in studies of humanized experimental animal models of lethal bacteremic pneumonia caused by resistance and tolerant strains was a slowing in the kinetics of beta-lactams bactericidal activity, especially for amoxicillin. Taken together, this preclinical data shows that microbiological resistance of pneumococci to beta-lactams has very little influence on a possible failure of recommanded treatment regimens for pneumococcal pneumonia. The high rate of multiple drug resistance, particularly among beta-lactam resistant strains, rules out the probabilistic use of macrolides. Conversely, fluoroquinolone (FQ) resistance remains low, inferior to 3%, and the same is true for ketolides (<1%). Only a global strategy of patient management in the use of these new drugs could ensure their long-term activity. The high mortality rate of hospitalized S. pneumoniae pneumonia will only be improved with a better understanding of the complex host-bacteria interactions.

Drug-resistant pneumococcal pneumonia: clinical relevance and approach to management

Community-acquired pneumonia is the most common infectious disease that causes death, with Streptococcus pneumoniae remaining the leading causative pathogen. The worldwide incidence of infections caused by pneumococci resistant to penicillin, macrolides, and other antimicrobial agents has increased at an alarming rate during the past 2 decades. Yet, these agents are still used as first-line empirical therapy in the outpatient setting. There are several reasons for this, including the infrequency of making a pathogen-specific diagnosis, the failure of studies to demonstrate the relevance of resistance, and the infrequency with which clinicians recognize clinical failures. Despite this, there is mounting evidence that supports the practice of using high doses of some antimicrobial agents, a more active antimicrobial agent within a class, or switching to another class of antimicrobial agents when a patient is identified as being at an increased risk of infection with a resistant pneumococcus. There is now information that will allow the physician to identify not only the patient at risk for infection with a resistant pneumococcus but also the antimicrobial class and, in some cases, the agent within the class to which the organism is more likely to be resistant. This will allow clinicians to better define optimal therapy for patients with community-acquired pneumonia.

Macrolide resistance in bacteremic pneumococcal disease: implications for patient management

BACKGROUND

Despite pneumococcal antibiotic resistance rates in excess of 25%, macrolides remain first-line agents for the treatment of community-acquired pneumonia.

METHODS

Prospective, population-based surveillance was conducted to identify cases of pneumococcal bacteremia in Toronto and Peel, Canada, between 2000 and 2004. "Macrolide failures" were defined as cases of bacteremia occurring during outpatient treatment with macrolide antibiotics or within 2 days after treatment. Macrolide susceptibility was determined according to Clinical Laboratory Standards Institute guidelines; common macrolide resistance mechanisms were determined by genotyping.

RESULTS

During the 5 years of surveillance, there were 1696 episodes of pneumococcal bacteremia (8.5 cases/100,000 population/year), of which 60 (3.5%) were failures of outpatient macrolide therapy. Resistant isolates were more common among cases of bacteremia after failure of macrolide therapy (37 [64%] of 58 cases) than among cases of bacteremia after failure of nonmacrolide antibiotics (16 [22%] of 74 cases; P<.001) or cases of bacteremia that occurred without prior antibiotic therapy (193 [12%] of 1569 cases; P<.001). Macrolide failures were significantly more common among cases of pneumococcal bacteremia with isolates exhibiting an erythromycin MIC of 1 microg/mL than among isolates exhibiting MICs < or = 0.25 microg/mL (3 [38%] of 8 cases vs. 21 [1.5%] of 1394 cases of bacteremia; P<.001). Increases in the MIC to 1 microg/mL were not associated with further increases in the likelihood of macrolide failure. Low-level resistance conferred by mefA and high-level resistance conferred by ermB were equally overrepresented among macrolide failures.

CONCLUSIONS

Macrolide resistance contributes to an increased risk of macrolide failure, irrespective of the underlying resistance mechanism or of the degree of elevation in erythromycin MIC.

Comparing gatifloxacin and clarithromycin in pneumonia symptom resolution and process of care

In looking for outcome differences beyond rates of cure, we prospectively compared the symptom resolution, side effects, and processes of care between the use of clarithromycin and gatifloxacin for the treatment of radiographically confirmed community-acquired pneumonia. We conducted a multicenter, randomized, open-label study comparing gatifloxacin monotherapy to clarithromycin alone or combined with ceftriaxone for patients with multiple risk factors. We measured the return to usual activities and symptoms over seven interviews ending 42 days after randomization. Admission and hospital discharge decision support were provided to treating physicians. We enrolled 266 patients over the age of 18 years between September 2000 and June 2003. The groups were similar in age and gender, with a mean age of 53.5+/-19.4 years, and were 54% female. Patient severity as determined by the number of risk factors and the Pneumonia Severity Index was similar between groups; 95% of the patients were low risk. A total of 91% of patients completed at least five of seven symptom interviews. In the clarithromycin study arm, 64% received concomitant therapy with ceftriaxone. We found no significant difference in return to usual activities, pneumonia-specific symptom scores, and 12-item short-form health survey scores. Individual symptom scores were similar except for bad taste and injection site soreness, which were higher in clarithromycin patients. The rates of hospital admission and length of stay were similar. The cost of antibiotic was higher in the clarithromycin group: $257 versus $110 for gatifloxacin. We found that gatifloxacin monotherapy is similar to clarithromycin given with or without ceftriaxone for the treatment of community-acquired pneumonia, except that antibiotic cost, bad taste, and injection site soreness favor the use of gatifloxacin.

Community-acquired pneumonia in Shanghai, China: microbial etiology and implications for empirical therapy in a prospective study of 389 patients

The aim of this multicenter study was to identify the causative pathogens of community-acquired pneumonia (CAP) in Shanghai, China, and to determine their susceptibility to antimicrobial agents. Pathogens obtained from 389 patients with documented CAP during 2001-2003 were identified by multiple diagnostic tools that included bacterial culture, polymerase chain reaction (PCR), and specific immunological assays. Susceptibility of the bacterial isolates was tested by the broth microdilution method. A specific pathogen was identified in 39.8% (155/389) of the patients: Haemophilus influenzae (n=80), Klebsiella spp. (n=15), Streptococcus pneumoniae (n=12), Staphylococcus aureus (n=6), Moraxella catarrhalis (n=1), other gram-negative organisms (n=9), and atypical pathogens that comprised Mycoplasma pneumoniae (n=42), Chlamydia pneumoniae (n=17), and Legionella pneumophila (n=2). Most H. influenzae isolates were susceptible to ampicillin (88.3%), and all were susceptible to macrolides. Of the S. pneumoniae isolates, 75% (9/12) were susceptible to penicillin, while 25% (3/12) were intermediately susceptible. H. influenzae and atypical pathogens are among the most important pathogens of CAP. Ampicillin, cephalosporins, and the newer fluoroquinolones can be used as empirical therapy for CAP in the Shanghai area. The efficacy of monotherapy with newer macrolides for CAP caused by S. pneumoniae requires further evaluation.

Optimal pharmacological therapy for community-acquired pneumonia: the role of dual antibacterial therapy

The optimal pharmacological therapy of community-acquired pneumonia (CAP) is one of the most ardently debated issues in medicine. Presently, most guidelines recommend either a fluoroquinolone alone or dual therapy with a third-generation cephalosporin plus a macrolide in patients hospitalised with CAP, but few provide clinicians with specific considerations for selecting from these agents. Despite a similar spectrum of activity and favourable resistance patterns (for fluoroquinolones and third-generation cephalosporins) against CAP pathogens, there is emerging evidence that dual therapy may be superior to monotherapy in certain populations.In patients with non-severe CAP, the evidence supports the use of either monotherapy or dual therapy in most patients; however, patients with severe CAP or bacteraemic pneumococcal CAP experience improved survival when treated with dual therapy. It is unclear from this evidence if any specific combination of agents is the most effective, but the combination of a third-generation cephalosporin plus a macrolide is the most extensively studied. Dual therapy was superior to monotherapy irrespective of the susceptibility of the aetiological pathogen, thus insufficient antimicrobial spectrum does not explain the disparity. The most likely explanation for improved outcomes with dual therapy is the combined effect of optimised antimicrobial spectrum (including atypicals), decreased impact of resistance to a single agent and the immunomodulatory effects of macrolides. Increasing resistance in patients with non-severe CAP warrants the consideration of dual therapy and perhaps a reappraisal of agents usually reserved for second-line therapy, including doxycycline, in these populations as well. In light of the available evidence, dual therapy should be strongly considered in all patients with severe CAP, especially when complicated by pneumococcal bacteraemia.

Bacteremic pneumococcal pneumonia associated with macrolide failure

Despite rising rates of macrolide resistance to Streptococcus pneumoniae, the current guidelines for outpatient treatment of community-acquired pneumonia include a macrolide as initial empiric therapy. There have only been a few previously documented cases of macrolide treatment failure in community-acquired pneumonia and there is controversy as to whether macrolide resistance in S. pneumoniae is clinically important. Reported here are two cases of community-acquired pneumonia caused by S. pneumoniae, one of which was fatal, that failed to respond to clarithromycin.

Clinical implications and treatment of multiresistant Streptococcus pneumoniae pneumonia

Streptococcus pneumoniae is the leading bacterial cause of community-acquired respiratory tract infections. Prior to the 1970s this pathogen was uniformly susceptible to penicillin and most other antimicrobials. However, since the 1990s there has been a significant increase in drug-resistant Streptococcus pneumoniae (DRSP) due, in large part, to increased use of antimicrobials. The clinical significance of this resistance is not definitely established, but appears to be most relevant to specific MICs for specific antimicrobials. Certain beta-lactams (amoxicillin, cefotaxime, ceftriaxone), the respiratory fluoroquinolones, and telithromycin are among several agents that remain effective against DRSP. Continued surveillance studies, appropriate antimicrobial usage campaigns, stratification of patients based on known risk factors for resistance, and vaccination programmes are needed to appropriately manage DRSP and limit its spread.

Empiric management of community‐acquired pneumonia in Australian emergency departments

OBJECTIVE

To describe empiric community-acquired pneumonia (CAP) management in Australian hospital emergency departments (EDs) and evaluate this against national guidelines, including use of the pneumonia severity index and antibiotic selection.

DESIGN

A multicentre, cross-sectional, retrospective audit, April 2003 to February 2005.

SETTING

37 Australian hospitals: 22 principal referral hospitals, six large major city hospitals, four large regional hospitals, four medium hospitals and one private hospital.

PARTICIPANTS

Adult patients with a diagnosis of CAP made in the ED. Data on 20 consecutive CAP ED presentations were collected in participating hospitals.

OUTCOME MEASURES

Documented use of the pneumonia severity index, initial antibiotic therapy prescribed in the ED, average length of stay, inpatient mortality, and concordance with national guidelines.

RESULTS

691 CAP presentations were included. Pneumonia severity index use was documented in 5% of cases. Antibiotic therapy covering common bacterial causes of CAP was prescribed in 67% of presentations, although overall concordance with national guidelines was 18%. Antibiotic prescribing was discordant due to inadequate empiric antimicrobial cover, allergy status (including contraindication to penicillin), inappropriate route of administration and/or inappropriate antibiotic choice according to recommendations. There was no significant difference between concordant and discordant antibiotic prescribing episodes in average length of stay (5.0 v 5.7 days; P = 0.22) or inpatient mortality (1.6% v 4.1%; chi2 = 1.82; P = 0.18).

CONCLUSIONS

Antibiotic therapy for CAP prescribed in Australian EDs varied. Concordance with national CAP guidelines was generally low. Targeted interventions are required to improve concordance.

Antibiotic susceptibility and serotype distribution in Streptococcus pneumoniae circulating in Italy: results of the SEMPRE surveillance study (2000-2002)

During 2000-2002, 20 clinical microbiology centres collected 1623 Streptococcus pneumoniae isolates. Susceptibility to penicillin, amoxicillin, amoxicillin/clavulanic acid, cefaclor, cefuroxime, cefotaxime, clarithromycin, ciprofloxacin, levofloxacin, rifampicin and teicoplanin was determined locally by the Etest and/or by the microdilution method by three co-ordinating centres. Total resistance to penicillin increased from 15.2% to 16.1% and macrolide resistance increased from 37.9% to 43.7%. Overall, the most effective drugs (>99% susceptible strains) were amoxicillin, amoxicillin/clavulanic acid, levofloxacin and rifampicin. The most frequent serotypes were: 23F (15.8%), 3 (10.8%) 14 (9.1%), 19F (9.1%), 6B (7.2%), 19A (6.9%) and 6A (4.8%). In conclusion, penicillin and macrolide resistance is increasing in Italy, whilst fluoroquinolone currently remains active. The most common serotypes circulating are included in the heptavalent conjugate vaccine, with the exception of type 3.

Quinolones in 2005: an update

Quinolones are one of the largest classes of antimicrobial agents used worldwide. This review considers the quinolones that are available currently and used widely in Europe (norfoxacin, ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin) within their historical perspective, while trying to position them in the context of recent and possible future advances based on an understanding of: (1) their chemical structures and how these impact on activity and toxicity; (2) resistance mechanisms (mutations in target genes, efflux pumps); (3) their pharmacodynamic properties (AUC/MIC and Cmax/MIC ratios; mutant prevention concentration and mutant selection window); and (4) epidemiological considerations (risk of emergence of resistance, clonal spread). Their main indications are examined in relation to their advantages and drawbacks. Overall, it is concluded that these important agents should be used in an educated fashion, based on a careful balance between their ease of use and efficacy vs. the risk of emerging resistance and toxicity. However, there is now substantial evidence to support use of the most potent drug at the appropriate dose whenever this is required.