A guide to the treatment of lower respiratory tract infections

Intravenous/oral sequential therapy in patients hospitalised with community-acquired pneumonia: which patients, when and what agents?

Cost and pharmacoeconomic aspects are becoming more and more important in antibacterial therapy. Nevertheless, antibacterial therapy is curative and initial use of the right antibacterial with high activity and low resistance rates against the relevant pathogens can help to save costs. A new trend in antibacterial therapy is sequential therapy (intravenous/oral) in hospitalised patients with moderate to severe infections. Large studies comparing intravenous therapy with sequential therapy (intravenous/oral) have shown equivalence in clinical and bacteriological outcome. One main indication investigated is community-acquired pneumonia (CAP). CAP requires prompt and effective antibacterial treatment and conventional therapy for patients hospitalised with CAP has typically been parenteral antibacterial therapy for 7 to 10 days. However, clinical evidence shows that in most patients the objective and subjective indicators of infection are substantially improved within the first 2 to 3 days of treatment. Today a large number of clinical trials in patients with CAP have been undertaken and sequential therapy with appropriate antibacterials used in suitable patients has been proven as a treatment option. This demonstrates pharmacoeconomic benefits without compromising antibacterial efficacy. Recommended antibacterials for intravenous/oral sequential therapy in patients with CAP are second- and third- generation cephalosporins, aminopenicillins plus a beta-lactamase inhibitor, and new fluoroquinolones.

Achieving a safe and early discharge for patients with community-acquired pneumonia

The rationale for achieving an early discharge for patients with CAP is that reduced length of stay can result in lower costs. When hospital discharge is premature, however, use of resources after discharge from the hospital may increase. This situation could increase overall cost and worsen quality of care. The objective should be to achieve a safe and early discharge. Several studies have evaluated methods for achieving this goal. Key findings from these studies are as follows: When a patient achieves clinical stability (e.g., systolic blood pressure, > or = 90 mm Hg; heart rate, < or = 100 beats/min; respiratory rate, < or = 24 breaths/min; temperature, < or = 38.3 degrees C [101 degrees F]; oxygen saturation, > or = 90%; able to eat; and stable mental status) or fulfills appropriate criteria (see Table 2), the patient may be eligible for switch from parenteral to oral antibiotics and early discharge. For many patients, this switch or discharge may occur on day 3 of hospitalization. When a patient is switched from parenteral to oral antibiotics, in many cases there does not appear to be a demonstrable clinical benefit to in-hospital observation. Elimination of in-hospital observation for patients who do not have an obvious reason for continued hospitalization potentially could reduce length of stay by 1 day. Improving efficiency of care reduces length of stay. This reduction may be accomplished by implementing clinical pathways, identifying and correcting causes of medically unnecessary hospital days, initiating early discharge planning, enlisting the services of a discharge coordinator, and organizing outpatient parenteral antibiotic treatment programs. These strategies are effective in many but not all patients, and their application should be tempered with careful clinical judgment.

Clinical efficacy and antimicrobial pharmacodynamics

Changes in the susceptibility of bacterial pathogens and the availability of new antimicrobial drugs mean that physicians need to understand the underlying pharmacodynamics of each antimicrobial therapy. Antimicrobial pharmacodynamics determine clinical efficacy and should therefore be carefully considered when selecting appropriate antibiotic agents in the therapeutic setting.

Prescribing habits of general practitioners in choosing an empirical antibiotic regimen for lower respiratory tract infections in adults in Sicily

The survey was carried out, between September 1995 and May 1996, in order to describe the prescriptive behaviour among Sicilian general practitioners (GPs) in choosing an empirical antibiotic regimen for LRTIs in adult patients and begin an educational process which involves the same GPs in decisions regarding their prescriptions and in performing local guidelines. Each practitioner filled out a questionnaire for each therapeutic intervention which ended with an antibiotic prescription. The questionnaire also enquired into the patient's characteristics, diseases to be treated and drug prescription. Doctors were asked to give an opinion about the severity assessment of the infectious disease before choosing the antibiotic treatment, in order to evaluate the prescriptive behaviour of physicians related to the patient's symptoms. Of all Sicilian GPs approached, 76 physicians from 25 Sicilian towns, with a patient population of 96,630, agreed to participate. The GPs used 49 different molecules and six different associations of two antibiotics. The most frequently used antibacterial agents were cephalosporins (55.0%). Penicillins (11.7%), fluoroquinolones (11. 4%), macrolides (10.1%) and combinations of penicillins with beta-lactamase inhibitors (7.9%), together, represented 41.1% of the remaining antibiotic prescriptions. The choice of the route of administration was significantly influenced by age of the patients, by symptoms and signs of the disease and by the presence of concurrent diseases rather than by bacteria suspected of causing the disease. The rather marked variation in antibiotic prescribing pattern for LRTIs among Sicilian GPs reflects lack of availability or knowledge of any local or national guidelines about the management of these diseases.

Antibiotics in acute bronchitis: a meta-analysis

PURPOSE

Most patients with acute bronchitis who seek medical care are treated with antibiotics, although the effectiveness of this intervention is uncertain. We performed a meta-analysis of randomized, controlled trials to estimate the effectiveness of antibiotics in the treatment of acute bronchitis.

SUBJECTS AND METHODS

English-language studies published January 1966 to April 1998 were retrieved using MEDLINE, bibliographies, and consultation with experts. Only randomized trials that enrolled otherwise healthy patients with a diagnosis of acute bronchitis, used an antibiotic in the treatment group and a placebo in the control group, and provided sufficient data to calculate an effect size were included.

RESULTS

We identified eight randomized controlled trials that satisfied all inclusion criteria. These studies used one of three antibiotics (erythromycin, doxycycline, trimethoprim/sulfamethoxazole). The use of antibiotics decreased the duration of cough and sputum production by approximately one-half day (summary effect size 0.21; 95% CI, 0.05 to 0.36). For specific symptoms, there were nonsignificant trends favoring the use of antibiotics: a decrease of 0.4 days of purulent sputum (95% CI, -0.1 to 0.8), a decrease of 0.5 days of cough (95% CI, -0.1 to 1.1), and a decrease of 0.3 days lost from work (95% CI, -0.6 to 1.1).

CONCLUSION

This meta-analysis suggests a small benefit from the use of the antibiotics erythromycin, doxycycline, or trimethoprim/sulfamethoxazole in the treatment of acute bronchitis in otherwise healthy patients. As this small benefit must be weighed against the risk of side effects and the societal cost of increasing antibiotic resistance, we believe that the use of antibiotics is not justified in these patients.

Levofloxacin versus cefuroxime axetil in the treatment of acute exacerbation of chronic bronchitis: results of a randomized, double-blind study

A randomized, double-blind, double-dummy, three-arm parallel design, multicentre study was conducted among adult patients with acute exacerbation of chronic bronchitis (AECB) in order to compare the efficacy and safety of two different doses of levofloxacin with cefuroxime axetil. A total of 832 patients were randomized to receive oral levofloxacin (250 mg od or 500 mg od) or oral cefuroxime axetil (250 mg bd) for 7-10 days. The primary efficacy analysis was based on the clinical response in patients with bacteriologically confirmed AECB, determined 5-14 days after the end of therapy (per-protocol population). Of 839 patients enrolled (at 71 centres in 14 countries), seven were not treated, giving an intention-to-treat (ITT) population of 832. In total, 281 patients received levofloxacin 250 mg, 280 received levofloxacin 500 mg and 271 received cefuroxime axetil. The cure rates in the ITT population were: levofloxacin 250 mg, 70% (196/281); levofloxacin 500 mg, 70% (195/280); cefuroxime axetil, 61% (166/271); those in the per-protocol population were: 78% (121/156), 79% (108/137) and 66% (88/134), respectively. Both doses of levofloxacin were at least as effective as cefuroxime axetil and were active against the main pathogens of clinical relevance (Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis). All three treatment regimens were equally well tolerated. In conclusion, the results show that levofloxacin (250 mg and 500 mg) od is effective and well tolerated in the treatment of AECB in adult patients.

Trends in the antimicrobial susceptibility of bacterial respiratory tract pathogens--findings of the Alexander Project 1992-1996

The Alexander Project is an ongoing, multicenter surveillance study of the antimicrobial susceptibility of community-acquired lower respiratory tract bacterial pathogens with testing undertaken in a central laboratory. During the period 1992-1995, isolates were collected from geographically separate centers in countries of the EU and various states in the USA. In 1996, the project was extended to centers in Mexico, Brazil, Saudi Arabia, South Africa, Hong Kong and other European countries not previously included. Within Europe, France and Spain are established as centers with a high prevalence of both penicillin-intermediate (MIC 0.12-1 mg/l) and resistant (MIC > or = 2 mg/l) strains of Streptococcus pneumoniae, with combined resistance rates in excess of 40% in Toulouse and Barcelona in 1996. Combined rates of intermediate and resistant strains in excess of 10% were found in 1996, the first year of sampling, in Belgium, Switzerland, the Slovak Republic and Hungary. Penicillin resistance has evolved in the USA during the period of study, with rates for combined pneumococcal isolates increasing from 5.6% in 1992 to 16.4% in 1996. Of the new, non-European centers joining the project in 1996, Mexico (intermediate 31.4%, resistant 15.7%) and, in particular, Hong Kong (intermediate 9.1%, resistant 50%) are centers with a high prevalence of penicillin resistance. Macrolide resistance has increased generally among pneumococcal isolates examined during the study period, both in penicillin-susceptible and resistant isolates, and was evident in 16.5% of the 2160 isolates collected during 1996. In four centers (London, UK; Genoa, Italy; Pokfulum, Hong Kong; Leuven, Belgium), macrolide resistance rates exceeded those of combined penicillin-intermediate and resistant strains; in 12/19 centers (63.2%) macrolide resistance was more prevalent than penicillin resistance. In 1996, macrolide resistance was found in excess of 10% of isolates in Poland, Hungary, London, UK, combined USA isolates, the Slovak Republic, Barcelona, Spain, Genoa, Italy, Mexico, Toulouse, France and Pokfulum, Hong Kong. beta-lactamase production was the principal mechanism of resistance found among isolates of Haemophilus influenzae, with rates in 1996 of around 20% or more in France, Belgium and Spain, and in excess of 10% in the UK and the Czech Republic. In the same year in non-European centers, Mexico (25%), Saudi Arabia (27.9%), Hong Kong (37.1%) and the USA (30.4% of combined isolates) had a high prevalence of beta-lactamase production. Isolates of beta-lactamase-negative, ampicillin-resistant H. influenzae were generally very uncommon, with only Barcelona, Spain consistently associated with rates in excess of 1%. beta-lactamase production in Moraxella catarrhalis was observed in over 90% of isolates tested in 1996.

Basing empiric treatment choices for respiratory tract infection on the results of the Alexander Project

For respiratory tract infection (RTI), antibiotics should have proven clinical efficacy against the major pathogens involved-Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. As the pattern of resistance to antimicrobials changes, the clinical effectiveness of these agents should be reviewed. However, clinical trials are time consuming and costly, and alternative ways of predicting clinical efficacy using susceptibility data have been investigated. Pharmacodynamic breakpoints have been suggested as providing the link between susceptibility data and clinical effectiveness and this is supported by emerging clinical evidence. Thus, using the data collected in the Alexander Project, guidelines for the treatment of RTI can be developed which reflect the local resistance profile and maximize the chances of clinical success.

Efficacy and safety of high dose intravenous ciprofloxacin in the treatment of bacterial pneumonia. Italian Ciprofloxacin Study Group

One hundred and fifty three hospitalized patients were enrolled in an open, prospective, multi-center study on the efficacy and safety of intravenous ciprofloxacin (400 mg i.v., b.i.d.) for acute bacterial pneumonia: 93 (63%) patients were valid for efficacy out of 148 valid for intention-to-treat analysis. The most commonly isolated organisms from 93 valid-for-efficacy patients were Pseudomonas aeruginosa (17%), Haemophilus influenzae and parainfluenzae (17%), Streptococcus aureus (14%) and Streptococcus pneumoniae (11%). Cure was achieved in 89/93 (95.7%) valid-for-efficacy patients; effective eradications were obtained in 42 (45%) and presumed eradications in 48 (52%) of the 93 patients. Mild or moderate adverse events (AE) occurred in 13/153 (8.5%) patients assessable for safety; all but one AE were rapidly reversible and only one treatment-stop (0.65%) was decided. The treatment of acute bacterial pneumonias with high-dose parenteral ciprofloxacin appears to be efficacious and well tolerated.

Sequential switch therapy for lower respiratory tract infections: a European perspective

Traditionally, serious lower respiratory tract infections (LRTIs) are treated in hospital and with parenteral antibiotics. During the past decade, there has been an impetus to reduce the overall cost of antimicrobial therapy. The availability of new oral antibiotics with superior pharmacokinetics profiles and safety has enabled clinicians increasingly to consider their use in managing serious infections effectively. This article reviews the current published literature regarding the practice of switch therapy for LRTIs, examining the evidence for efficacy, safety, appropriate timing of the switch, the economic benefits, and the suitability of various antibiotics. There is an emphasis on comparing current European and US experience and examining key strategies in implementing such programs and means of assessing their impact.

Efficacy and safety of grepafloxacin 600 mg daily for 10 days in patients with community-acquired pneumonia

The efficacy and safety of grepafloxacin in treating patients with community-acquired pneumonia (CAP) was assessed in an open-label, noncomparative study. Patients (N = 273) received grepafloxacin 600 mg QD for 10 days. A total of 237 patients (87%) completed the study. In assessable patients, the clinical success rate at follow-up (4 to 6 weeks after the last dose) was 89% (211/238 patients). In microbiologically assessable patients, the eradication rate at follow-up was 95% (86/91 isolates). Grepafloxacin was highly effective in the treatment of bacterial CAP caused by Streptococcus pneumoniae (irrespective of penicillin susceptibility), Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis, and Staphylococcus aureus and in the therapy of atypical pneumonia caused by Mycoplasma pneumoniae and Legionella pneumophila. Grepafloxacin was well tolerated, with the most frequently reported drug-related adverse events being taste perversion and nausea. Grepafloxacin 600 mg QD for 10 days was highly effective and well tolerated in the treatment of patients with CAP.

Clarithromycin. A review of its efficacy in the treatment of respiratory tract infections in immunocompetent patients

Clarithromycin is a broad spectrum macrolide antibacterial agent active in vitro and effective in vivo against the major pathogens responsible for respiratory tract infections in immunocompetent patients. It is highly active in vitro against pathogens causing atypical pneumonia (Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella spp.) and has similar activity to other macrolides against Staphylococcus aureus. Streptococcus pyogenes, Moraxella catarrhalis and Streptococcus pneumoniae. Haemophilus influenzae is susceptible or intermediately susceptible to clarithromycin alone, but activity is enhanced when the parent drug and metabolite are combined in vitro. Absorption of clarithromycin is unaffected by food. More than half of an oral dose is systemically available as the parent drug and the active 14-hydroxy metabolite. Pharmacokinetics are nonlinear, with plasma concentrations increasing in more than proportion to the dosage. First-pass metabolism results in the rapid appearance of the active metabolite 14-hydroxy-clarithromycin in plasma. Clarithromycin and its active metabolite are found in greater concentrations in the tissues and fluids of the respiratory tract than in plasma. Dosage adjustments are required for patients with severe renal failure, but not for elderly patients or those with hepatic impairment. Drug interactions related to the cytochrome P450 system may occur with clarithromycin use. In addition to the standard immediate-release formulation for administration twice daily, a modified-release formulation of clarithromycin is now available for use once daily. In dosages of 500 to 1000 mg/day for 5 to 14 days, clarithromycin was as effective in the treatment of community-acquired upper and lower respiratory tract infections in hospital and community settings as beta-lactam agents (with or without a beta-lactamase inhibitor), cephalosporins and most other macrolides. Clarithromycin was similar in efficacy to azithromycin in comparative studies and is as effective as and better tolerated than erythromycin. Adverse events are primarily gastrointestinal in nature, but result in fewer withdrawals from therapy than are seen with erythromycin. Clarithromycin provides similar clinical and bacteriological efficacy to that seen with beta-lactam agents, cephalosporins and other macrolides. It offers a cost-saving alternative to intravenous erythromycin use in US hospitals and is available in both once-daily and twice-daily formulations. The spectrum of activity of clarithromycin against common and emerging respiratory tract pathogens may make it suitable for use in the community as empirical therapy of respiratory tract infections in both children and adults.

Cefuroxime axetil. A review of its antibacterial activity, pharmacokinetic properties and therapeutic efficacy

Cefuroxime axetil is an oral cephalosporin which is rapidly hydrolysed to the active parent compound, cefuroxime. Cefuroxime has a broad spectrum of in vitro antibacterial activity which encompasses methicillin-sensitive staphylococci and the common respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Moraxella (Branhamella) catarrhalis and group A beta-haemolytic streptococci. Cefuroxime has broad spectrum activity against the beta-lactamase positive respiratory pathogens H. influenzae and M. catarrhalis; it is also active against penicillin-susceptible and -intermediate strains of S. pneumoniae. In clinical trials, cefuroxime axetil (administered twice daily) has been evaluated in the treatment of upper and lower respiratory tract infections and has demonstrated similar efficacy to established antibacterial agents, including amoxicillin/clavulanic acid and cefaclor. Five days' treatment with cefuroxime axetil was recently shown to be as effective as 10 days' treatment with either cefuroxime axetil or amoxicillin/clavulanic acid in patients with acute otitis media or acute bronchitis. Cefuroxime axetil was at least as effective as phenoxymethylpenicillin (penicillin V) in the treatment of patients with group A beta-haemolytic streptococcal tonsillopharyngitis. A number of studies have evaluated the efficacy of cefuroxime axetil as the oral component of intravenous to oral sequential therapy in hospitalised patients with lower respiratory tract infection. In each study patients received parenteral cefuroxime for approximately 2 days followed by cefuroxime axetil for 5 to 10 days. In comparative studies, cefuroxime sequential therapy was as effective as amoxicillin/ clavulanic acid sequential therapy and full courses of parenteral cefuroxime, cefotiam or cefoperazone. Adults with urinary tract infections and skin infections were also effectively treated with cefuroxime axetil, as were adults and adolescents with early stage lyme disease. Cefuroxime axetil is associated with a low incidence of adverse events, with gastrointestinal disturbances being the most frequently observed. Thus, cefuroxime axetil is an effective and convenient treatment for a wide range of infections and may be considered a therapeutic option when empirical treatment of community-acquired infections is required. Moreover, given the promising results of several intravenous/oral sequential treatment studies, cefuroxime axetil may also become established as an oral component of sequential treatment regimens.

Sequential therapy in the hospital management of lower respiratory infections

Conventional treatment for patients hospitalized with lower respiratory infections, such as pneumonia or bronchitis, typically consists of parenteral antibiotic therapy for 7-10 days. The clinical evidence, however, shows that in most patients the objective and subjective indicators of infection are substantially improved within the first 2 days of treatment. Thus, many of these patients can be switched to oral antibiotics after 2-3 days of parenteral therapy, with no loss in efficacy of treatment and with substantial savings in terms of cost of care and length of hospital stay. beta-Lactam antibiotics are a frequent choice for the oral component following short-term intravenous therapy. The results of recent, large-scale comparative clinical trials support the usefulness of this treatment approach, known as sequential therapy.