Treatment of severe pneumonia in hospitalized patients: results of a multicenter, randomized, double-blind trial comparing intravenous ciprofloxacin with imipenem-cilastatin. The Severe Pneumonia Study Group

Healthcare-associated pneumonia: principles and emerging concepts on management

Healthcare-associated pneumonia (HCAP) is a relatively new entity that includes pneumonia occurring in healthcare settings other than acute-care hospitals. Many patients with HCAP are at greater risk for colonization and infection with multi-drug resistant (MDR) bacteria such as Pseudomonas aeruginosa, Gram-negative bacilli-producing extended-spectrum beta-lactamases and methicillin-resistant Staphylococcus aureus. Infections with these MDR pathogens require different empiric antibiotic therapy. To avoid initiation of inappropriate antibiotic therapy that may result in poorer patient outcomes, new principles for HCAP management were outlined in the 2005 American Thoracic Society and Infectious Diseases Society of America guidelines. These guidelines were suggested for patients assessed in acute-care hospitals and clinics, and may not be applicable for all patients with suspected HCAP in nursing homes and other long-term care settings. This review article addresses HCAP management strategies in both clinical settings.

The role of carbapenems in the treatment of severe nosocomial respiratory tract infections

The prevalence of antibiotic-resistant bacteria continues to increase, particularly in patients in the intensive care unit with nosocomial pneumonia. The intention of this review is to provide an overview of severe nosocomial pneumonia, carbapenems and the problem of bacterial resistance to antimicrobial agents. Attention was focused on the efficacy, safety and pharmacodynamics of imipenem, meropenem, ertapenem and doripenem. Issues on the impact of appropriate empiric antibiotic therapy for nosocomial pneumonia patients considered at risk for resistant pathogens are discussed. Critical decision making regarding the use of carbapenems for treating severe nosocomial pneumonia requires careful consideration of the four Ds of optimal antimicrobial therapy: right Drug, right Dose, De-escalated to pathogen-directed therapy and right Duration of therapy.

Carbapenems: a potent class of antibiotics

The purpose of this review is to assess the relative strengths and weaknesses of individual members of the carbapenem class of antibiotics. Clinical trials and review articles were identified from a Medline search (1979 - July 2006), in addition to, reference citations from identified publications, abstracts from the Interscience Conferences on Antimicrobial Agents and Chemotherapy and the 12th International Congress on Infectious Disease, and package inserts. Articles in English were reviewed, with emphasis on those containing efficacy or safety data. Carbapenems bind to critical penicillin-binding proteins, disrupting the growth and structural integrity of bacterial cell walls. They provide enhanced anaerobic and Gram-negative coverage as compared with other beta-lactams and their stability against extended-spectrum beta-lactamases (ESBLs) makes them an effective treatment option. The most common adverse effects are infusion-site complications and gastrointestinal distress. Ertapenem has limited efficacy against non-fermenting, Gram-negative bacteria, restricting its use to community-acquired infections. Imipenem is slightly more effective against Gram-positive organisms and meropenem slightly more effective against Gram-negative organisms. However, both have broad-spectrum activity, including non-fermenting, Gram-negative bacteria. Among non-fermenting, Gram-negatives, resistance to imipenem in particular is increasing. Doripenem is in late-stage clinical development and combines the broad-spectrum coverage of imipenem and meropenem, and more potent activity against Pseudomonas aeruginosa. Due to the increasing challenges represented by ESBLs and multi-drug resistant organisms, the carbapenems are assuming a greater role in the treatment of serious infections. Imipenem and meropenem are presently available and have been shown to be effective against nosocomial infections. Doripenem is an investigational carbapenem that has completed Phase III clinical trials and that has the potential to improve on this efficacy and minimize the emergence of resistance to the carbapenem class.

Empiric antibiotic therapy for suspected ventilator-associated pneumonia: a systematic review and meta-analysis of randomized trials

OBJECTIVE

To compare specific antibiotic regimens, and monotherapy vs. combination therapy, for the empirical treatment of ventilator-associated pneumonia (VAP).

DESIGN

Meta-analysis.

DATA SOURCE

Medline, Embase, Cochrane register of controlled trials, study authors, and review articles.

STUDY SELECTION

We included randomized controlled trials that evaluated empirical parenteral antibiotic regimens for adult patients with clinically suspected VAP.

DATA SELECTION

Two independent review groups searched the literature, extracted data, and evaluated trial quality. The primary outcome was all-cause mortality; secondary outcomes included treatment failure. Relative risks were pooled using a random effects model.

RESULTS

We identified 41 trials randomizing 7,015 patients and comparing 29 unique regimens. Methodological quality was low, reflecting low rates of complete follow-up (43.9%), use of a double-blinded interventional strategy (14.6%), and randomization concealment (48.6%). Overall mortality was 20.3%; treatment failure occurred in 37.4% of patients who could be evaluated microbiologically. No mortality differences were observed between any of the regimens compared. Only one of three pooled comparisons yielded a significant difference for treatment failure: The combination of ceftazidime/aminoglycoside was inferior to meropenem (two trials, relative risk 0.70, 95% confidence interval 0.53-0.93). Rates of mortality and treatment failure for monotherapy compared with combination therapy were similar (11 trials, relative risk for mortality of monotherapy 0.94, confidence interval 0.76-1.16; and relative risk of treatment failure for monotherapy 0.88, confidence interval 0.72-1.07).

CONCLUSIONS

Monotherapy is not inferior to combination therapy in the empirical treatment of VAP. Available data neither identify a superior empirical regimen nor conclusively conclude that available regimens result in equivalent outcomes. Larger and more rigorous trials evaluating the choice of, and even need for, empirical therapy for VAP are needed.

Empiric antibiotic coverage of atypical pathogens for community acquired pneumonia in hospitalized adults

BACKGROUND

Community acquired pneumonia (CAP) is caused by various pathogens, traditionally divided to 'typical' and 'atypical'. Initial antibiotic treatment of CAP is usually empirical, customarily covering both typical and atypical pathogens. To date, no sufficient evidence exists to support this broad coverage, while limiting coverage is bound to reduce toxicity, resistance and expense.

OBJECTIVES

To assess the efficacy and need of adding antibiotic coverage for atypical pathogens in hospitalized patients with CAP, in terms of mortality and successful treatment.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 1) which includes the Acute Respiratory Infection Group's specialized register; MEDLINE (January 1966 to March 2007); and EMBASE (January 1980 to January 2007).

SELECTION CRITERIA

Randomized trials of adult patients hospitalized due to CAP, comparing antibiotic regimens with atypical antibiotic coverage to a regimen without atypical antibiotic coverage.

DATA COLLECTION AND ANALYSIS

Two review authors independently appraised the quality of each trial and extracted the data from included trials. Relative risks (RR) with 95% confidence intervals (CI) were estimated, assuming an intention-to-treat (ITT) basis for the outcome measures.

MAIN RESULTS

Twenty five trials were included, encompassing 5244 randomized patients. There was no difference in mortality between the atypical arm and the non-atypical arm (RR 1.15; 95% CI 0.85 to 1.56). The atypical arm showed an insignificant trend toward clinical success and a significant advantage to bacteriological eradication, which disappeared when evaluating methodologically high-quality studies alone. Clinical success for the atypical arm was significantly higher for Legionella pneumophilae (L. pneumophilae) and non-significantly lower for pneumococcal pneumonia. There was no significant difference between the groups in the frequency of (total) adverse events, or those requiring discontinuation of treatment. However, gastrointestinal events were more common in the non-atypical arm (RR 0.73, 95% CI 0.54 to 0.99). All but two included trials compared a single atypical antibiotic to a beta-lactam, while no trials assessing the addition of an atypical antibiotic to a beta-lactam were identified.

AUTHORS' CONCLUSIONS

No benefit of survival or clinical efficacy was shown to empirical atypical coverage in hospitalized patients with CAP. This conclusion relates mostly to the comparison of quinolone monotherapy to beta-lactams (BL) or cephalosporins. Further trials, comparing BL or cephalosporins therapy to BL or cephalosporins combined with a macrolide in this population, using mortality as its primary outcome, should be performed.

Ventilator-associated pneumonia: impact of organisms on clinical resolution and medical resources utilization

BACKGROUND

Clinical resolution of ventilator-associated pneumonia (VAP) determines the duration of treatment and mechanical ventilation. The aim of this study was to evaluate the influence of organisms and their susceptibility to treatment on outcomes.

METHODS

Prospective observational study in three teaching ICUs. Sixty episodes of VAP with appropriate therapy (Haemophilus influenzae, 15 episodes; methicillin-sensitive Staphylococcus aureus [MSSA], 15 episodes; Pseudomonas aeruginosa, 15 episodes; and methicillin-resistant S aureus [MRSA], 15 episodes), and 30 episodes with initial inappropriate therapy, all due to P aeruginosa, were compared. The main outcome measures were clinical resolution variables and, in survivors, length of mechanical ventilation after VAP onset.

RESULTS

A significant delay in the resolution of hypoxemia was observed in VAP episodes due to MRSA and P aeruginosa with inappropriate antibiotic therapy (IAT) (median time to resolution, 10 and 8 days, respectively) when compared with the remaining pathogens (median time to resolution, 2 days). A multiple regression model, adjusted for disease severity, confirmed the delayed clinical resolution for MRSA and P aeruginosa with IAT. Similar associations were documented for defervescence. Among survivors, the median duration of mechanical ventilation after VAP onset was significantly longer for MRSA (17 days) and P aeruginosa IAT (11 days) when compared with episodes due to H influenzae or MSSA (6 days). Multiple regression analysis, adjusted for disease severity, confirmed that MRSA required significantly (R(2) = 0.132; p < 0.01) longer respiratory support than other organisms.

CONCLUSIONS

When treated promptly, the resolution of VAP due to MSSA, H influenzae, and P aeruginosa was comparable. The resolution of MRSA VAP, regardless of the appropriateness of initial antibiotic therapy, was associated with longer respiratory support.

Use of aerosolized aminoglycosides in the treatment of Gram-negative ventilator-associated pneumonia

BACKGROUND AND PURPOSE

Ventilator-associated pneumonia (VAP) in the surgical intensive care unit (ICU) is associated with substantial morbidity and mortality. Affected patients are at higher risk for infection with multi-drug-resistant (MDR) pathogens, often necessitating therapeutic regimens of two parenteral antibiotics. Aerosolized antibiotics achieve high alveolar concentrations and have been reported anecdotally to have value in the treatment of VAP. This study examined the role of aerosolized aminoglycosides in the treatment of VAP in surgical ICU patients.

METHODS

We reviewed retrospectively the medical records of 22 patients who received aerosolized aminoglycosides in conjunction with parenteral antibiotics for VAP in the surgical ICU. Sixteen patients received inhaled tobramycin, and six received inhaled amikacin. Demographic information and data on the length of stay (LOS), mortality rate, days of antibiotic therapy, days of mechanical ventilation, and recurrence of VAP were collected. Results of bronchoscopic and sputum cultures were reviewed to identify bacterial pathogens and antimicrobial susceptibilities.

RESULTS

The average duration of mechanical ventilation was 31 +/- 12 days, the mean ICU LOS was 41 +/- 13 days, and the mean hospital LOS was 71 +/- 25 days. There were three deaths. The average duration of mechanical ventilation after initiation of aerosolized antibiotics was 4.3 days. Seven patients (40%) developed recurrent pneumonia with the same pathogen, but only one had a change in antibiotic susceptibility pattern. There were no renal or pulmonary complications of aminoglycoside treatment.

CONCLUSIONS

Ventilator-associated pneumonia in critically ill patients is associated with substantial morbidity, longer ICU stays, and prolonged mechanical ventilation. Along with systemic therapy, aerosolized aminoglycosides are valuable adjuncts in select patients with minimal risk of antibiotic resistance.

Pseudomonas aeruginosa infections in the Intensive Care Unit: can the adequacy of empirical beta-lactam antibiotic therapy be improved?

Inadequate empirical antibiotic therapy for serious Pseudomonas aeruginosa infections has been linked to increased mortality. We performed a retrospective cohort study of consecutive patients with ventilator-associated pneumonia, bacteraemia or other sterile-site infections caused by P. aeruginosa occurring during Intensive Care Unit admissions. One hundred and fifty-eight episodes of serious infection with P. aeruginosa occurred in 140 patients. Empirical antibiotic therapy was microbiologically adequate in 67% of episodes of infection. Patients with P. aeruginosa isolates resistant to piperacillin/tazobactam or cefepime were more likely to have received these antibiotics in the month prior to the P. aeruginosa infection or to have had a Gram-negative bacillus resistant to these antibiotics isolated in the month prior to the P. aeruginosa infection. From these data, we have developed simple algorithms for empirical antibiotic choice in seriously ill patients with suspected P. aeruginosa infections based on prior antibiotic exposure and prior isolation of antibiotic-resistant organisms. Application of these algorithms would have improved the adequacy of empirical antibiotic therapy from 67% to 80-84%. Routine empirical addition of amikacin to the beta-lactam would have increased the adequacy of the antibiotics to 96%. We conclude that knowledge of the prior receipt of beta-lactam antibiotics with activity against P. aeruginosa and the isolation of Gram-negative bacilli resistant to such antibiotics in the recent past can readily increase the adequacy of empirical antibiotic therapy for suspected P. aeruginosa infections.

Evaluation of the performance of a modified Acute Physiology and Chronic Health Evaluation (APACHE II) scoring system for critically ill patients in emergency departments in Hong Kong

INTRODUCTION

Numerous prognostic predictive models have been developed for critically ill patients, many of which are primarily designed for use in intensive care units. The objective of this study was to evaluate the accuracy of a modified Acute Physiology and Chronic Health Evaluation (APACHE II) scoring system in predicting the mortality for critically ill patients managed in emergency department (ED) resuscitation rooms in Hong Kong.

METHOD

A multi-centre, prospective study was conducted for patients managed in the resuscitation rooms of the EDs of four major hospitals, including one university teaching hospital. The primary outcome measure was 14 day all-cause mortality and the secondary outcome measure was the length of stay in hospital.

RESULTS

Of 867 patients recruited between 4 and 30 April 2004, 106 (12.2%) patients died. The modified APACHE II score was found to be significantly higher in non-survivors compared to survivors (mean+/-S.D.: 21.2+/-7.7 versus 14.4+/-7.1, p<0.001). The area under the curve for modified APACHE II in predicting mortality was 0.743 (95% CI, 0.696-0.790).

CONCLUSION

The modified APACHE II score is only a moderate predictor of mortality for critically ill patients managed in the resuscitation rooms of EDs in Hong Kong. A more ED specific scoring method is required.

De-escalation therapy in ventilator-associated pneumonia

PURPOSE OF REVIEW

To describe the use of a 'de-escalation' strategy to deliver appropriate empiric therapy for ventilator-associated pneumonia, without the overuse of antibiotics.

RECENT FINDINGS

Initial empiric therapy can be appropriate in 80-90% of ventilator-associated pneumonia patients, if it is selected on the basis of local microbiologic data or individual patient surveillance cultures. Following initial empiric therapy, de-escalation means using microbiologic and clinical data to change from an initial broad-spectrum, multidrug empiric therapy regimen to a therapy with fewer antibiotics and agents of narrower spectrum. In spite of early success with this approach there is an opportunity to de-escalate more often, particularly in patients with negative pretherapy cultures, and in those whose cultures show multidrug-resistant organisms, including Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. In addition, it is possible to reduce the total duration of therapy, particularly when the initial therapy is accurate. When de-escalation has been employed, it has led to less antibiotic usage, shorter durations of therapy, fewer episodes of secondary pneumonia and reduced mortality, without increasing the frequency of antibiotic resistance.

SUMMARY

De-escalation is a promising strategy for optimizing the responsible use of antibiotics while allowing the delivery of prompt and appropriate empiric therapy of ventilator-associated pneumonia.

Aerosolised antibacterials for the prevention and treatment of hospital-acquired pneumonia

Aerosolised administration of antibacterials remains theoretically attractive for the prevention and treatment of hospital-acquired pneumonia (HAP) because of the ability to generate high drug concentrations at the site of infection. There is renewed interest in this area because of the shortcomings of current therapies and increasing multidrug resistance in Gram-negative organisms. Clinical trials of aerosolised or endotracheally administered antibacterials for HAP prevention have generally been positive; however, early trials were hampered by the development of resistance related to indiscriminate use. More recent trials have shown efficacy at HAP prevention without adverse effects on microflora as a result of more limited usage. However, prophylactic aerosolised antibacterials still need to be studied in large randomised trials before they could enter widespread use. The treatment of HAP with aerosolised antibacterials has mostly been reported in case series without control groups. Both early reports with aminoglycosides and the more recent use of colistin have reported very good response rates; even with organisms such as Pseudomonas aeruginosa and Acinetobacter baumannii. Aerosolised antibacterials were almost always added to intravenous therapy. On the basis of these reports, the current HAP guidelines allow the addition of aerosolised antibacterials in selected patients with multidrug-resistant organisms. This seems to be a reasonable recommendation until large trials are performed. Overall, toxicity was relatively low in the publications reviewed. Aerosolised drug administration in mechanically ventilated patients requires attention to a number of factors in order to maximise drug deposition in the lung.

[Assessment of patients with poor resolution of HAP]

Emphasis in VAP management is now shifting to the effectiveness of antibiotic therapy and its effect on subsequent mortality. As many as 62% of patients with VAP meet a set of objective criteria for failure to respond. The predominant microorganisms associated with failure of therapy are Pseudomonas aeruginosa and methicillin-resistant S. aureus (MRSA). Multiple causes of failure to respond in VAP exist: compromised host immunity, occult antibiotic resistance, inadequate antibiotic dosing, and concomitant or subsequent superinfections. The diagnosis of antibiotic failure and distinguishing failure from superinfection or noninfectious mimics is difficult because clinical criteria alone are inadequate. Microbiologic response is accurate only if quantitative cultures are used. Biochemical markers may be more accurate than clinical but still don't discriminate between causes. The appropriate diagnostic strategy and treatment algorithms have not been fully addressed and more research is clearly needed.

Impact of ceftazidime restriction on gram-negative bacterial resistance in an intensive care unit

The present study included three periods: (1) a 12-month pre-restriction and control period in 2001; (2) a 12-month restriction period with reduced ceftazidime prescribing in favor of piperacillin-tazobactam (2002); (3) and a 24 month post-restriction period (2003-2004). Note that, for results, P represents the difference between 2002 and 2001; P', the difference between 2003 and 2001; and P'', the difference between 2004 and 2001. No changes in hygiene practices were observed during these three periods. The purpose of this study was to assess the effect of reducing ceftazidime use in an intensive care unit (ICU) upon Gram-negative bacterial resistance, particularly as regards Pseudomonas aeruginosa. During the three periods of the study, patients were similar concerning age, Simplified Acute Physiology Score (SAPSII), the site of nosocomial infection, and the requirements for mechanical ventilation (75% in 2001, 76% in 2002, 74% in 2003, and 85% in 2004). The most commonly isolated pathogens were P. aeruginosa, Acinetobacter baumannii, and Enterobacteriaceae. The use of ceftazidime decreased significantly from 12.6% in 2001 to 9% in 2002, to 3% in 2003 (P' = 0.0009), and 2.6% in 2004 (P'' = 0.0001) in favor of piperacillin-tazobactam (0% 2001 to 3.7% in 2003; P' = 0.002; and 5% in 2004; P'' = 0.0001). Simultaneously, we observed a significant decrease in isolates of P. aeruginosa resistant to piperacillin-tazobactam (P = 0.03; P' = 0.004; P'' = 0.009), and those resistant to imipenem in 2003 (P' = 0.008). We also noted a significant decrease in A. baumannii isolates resistant to ceftazidime (P' = 0.01; P'' = 0.0004) and those resistant to imipenem in both 2002 and 2004 (P = 0.03; P'' = 0.04), and a considerable decrease in isolates of Klebsiella pneumoniae producing expanded spectrum betalactamase (ESBL) in 2003 and 2004 (P' = 0.04; P'' = 6.10(-5)). In contrast, we noted an increase in penicillinase-producing isolates of K. pneumoniae, from 6% in 2001 to 16% in 2002 (p = 0.01), 20% in 2003 (P' = 0.001), and 32% in 2004 (P'' = 10(-6)). We concluded that restriction of ceftazidime use was demonstrated to be efficient in reducing antimicrobial resistance, especially to K. pneumoniae ESBL.

Parenteral and Inhaled Colistin for Treatment of Ventilator-Associated Pneumonia

The spectrum of available therapeutic options has become drastically narrowed in recent years, particularly for nosocomial multidrug-resistant gram-negative pathogens. This therapeutic void has created a resurgence of interest in colistin. In 5 published series since 1999, clinical response rates for pneumonia due to Pseudomonas aeruginosa or Acinetobacter baumannii treated with intravenous colistin have ranged from 25% to 62%, despite high severity of illness at baseline. De novo nephrotoxicity was observed in 8%-36% of patients, despite close attention to both appropriate dosing and duration of treatment. Neurotoxicity, which was commonly described in the old colistin era, has been exceedingly rare in recent experience. Aerosolized therapy as an adjunct to systemic treatment appears promising, but the current published data are much too limited to allow determination of the incremental benefit of the addition of aerosolized treatment to systemic treatment. Colistin is a reasonably safe last-line therapeutic alternative for pneumonia due to multi- or panresistant P. aeruginosa or A. baumannii.

The Epidemiological Profile of Infections with Multidrug-Resistant Pseudomonas aeruginosa and Acinetobacter Species

Isolates of Pseudomonas aeruginosa or Acinetobacter species that are resistant to all, or almost all, commercially available antibiotics are now prevalent worldwide. Typically, these strains are recovered from patients in intensive care units who have ventilator-associated pneumonia. "Panresistant" strains can be defined as strains that are resistant to all beta -lactam and quinolone antibiotics recommended as empirical therapy for ventilator-associated pneumonia. These strains are well adapted to the hospital environment--molecular epidemiological studies have frequently revealed that only 1 or 2 clones caused outbreaks in intensive care units. However, panresistant strains may also be selected by antibiotic use. Given the lack of antibiotic options to treat infection with panresistant strains, enhanced surveillance for these organisms is necessary at unit-specific, institutional, and national levels.

Use of quantitative cultures and reduced duration of antibiotic regimens for patients with ventilator-associated pneumonia to decrease resistance in the intensive care unit

Ventilator-associated pneumonia is responsible for approximately half of the infections acquired in the intensive care unit and represents one of the principal reasons for the prescription of antibiotics in this setting. Invasive diagnostic methods, including bronchoalveolar lavage and/or protected specimen bronchial brushing, could improve the identification of patients with true bacterial pneumonia and facilitate decisions of whether to treat. These techniques also permit rapid optimization of the choice of antibiotics in patients with proven bacterial infection, once the results of respiratory tract cultures become available, based on the identity of the specific pathogens and their susceptibility to specific antibiotics, to avoid prolonged use of a broader spectrum of antibiotic therapy than is justified by the available information. Because unnecessary prolongation of antibiotic therapy for patients with true bacterial infection may lead to the selection of multidrug-resistant microorganisms without improving clinical outcome, efforts to reduce the duration of therapy for nosocomial infections are also warranted. An 8-day regimen can probably be standard for patients with ventilator-associated pneumonia. Possible exceptions to this recommendation include immunosuppressed patients, patients who are bacteremic or whose initial antibiotic therapy was not appropriate for the causative microorganism(s), and patients whose infection is with very difficult-to-treat microorganisms and show no improvement in clinical signs of infection.

Risk factors of superinfection following imipenem/cilastatin therapy in hospitalised patients with acute exacerbations of severe chronic obstructive pulmonary disease

Imipenem is often used in treatment of acute exacerbations of severe chronic obstructive pulmonary disease (COPD). Superinfection following imipenem therapy is a common cause of treatment failure and high economic burden. This study is aimed to explore any clinical factors which determine the risk of superinfection after imipenem treatment in acute exacerbations of severe COPD. A prospective observational study was conducted in a 5-bed respiratory intensive care unit of a Chinese University hospital. Fifty-one patients with acute exacerbations of severe COPD who were hospitalised and treated with imipenem for more than 3 days were enrolled during 1.5 year. The associations between the risk of superinfection and potential factors were analysed by logistic regression. Forty-seven out of 51 patients (92.2%) had their symptoms and signs improved at the end of imipenem treatment. Superinfections were developed in 12 patients, and the superinfection rate was as high as 30.8% (12 out of 39 patients with definite bacteriologic responses). The frequent superinfecting organisms were Stenotrophomonas maltophilia and Pseudomonas aeruginosa. Among a wide range of potential risk factors, we found that lower blood pH, previous cephalosporines treatment and longer period of imipenem treatment are independently associated with a higher risk of superinfection. The risk of superinfection following imipenem treatment in hospitalised patients with acute exacerbations of COPD was high. Lower blood pH, previous cephalosporines treatment and longer period of imipenem treatment all increased the risk of superinfection.

Levofloxacin in the treatment of ventilator-associated pneumonia

The use of levofloxacin in critically ill patients has progressively increased since commercial marketing of the drug in 1999, despite the fact that few studies have been designed to assess the use of levofloxacin in this population. Pharmacological characteristics, broad spectrum of activity, and tolerability account for the high interest in the drug for the treatment of different infectious diseases, including ventilator-associated pneumonia (VAP), and the recommendation of levofloxacin in guidelines developed by a number of scientific societies. According to pharmacokinetic-pharmacodynamic data, it seems reasonable to assume that an increase in activity follows from a larger dose, so that 500 mg/12 h is adequate in patients with VAP. In critically ill patients with VAP, levofloxacin monotherapy is indicated for empirical treatment of patients with early onset pneumonia without risk factors for multiresistant pathogens, and in combination therapy for late onset VAP or for patients at risk for multiresistant pathogens. The use of levofloxacin in combination therapy is supported by multiple reasons, including: increased empirical coverage in infections with suspected intracellular pathogens; substitution for more toxic antimicrobial agents (e.g., aminoglycosides) in patients with renal dysfunction and in those at risk for renal insufficiency; and severity of systemic response to infection (septic shock) that justifies multiple treatment with better tolerated antibiotics. The availability of the oral formulation allows sequential therapy, switching from the intravenous route to the oral route. Levofloxacin is well tolerated by critically ill patients, with few adverse events of mild to moderate severity.

Risk of emergence of Pseudomonas aeruginosa resistance to β-lactam antibiotics in intensive care units

OBJECTIVE

The emergence of Pseudomonas aeruginosa resistance to antimicrobial drugs is frequent in intensive care units and may be correlated with the use of some specific drugs. The purpose of our study was to identify a relationship between the use of various beta-lactam antibiotics and the emergence of resistance and to characterize the mechanism of resistance involved.

DESIGN

We conducted an open prospective study over a 3-yr period by including all patients in whom P. aeruginosa had been isolated from one or more specimens: bronchial aspiration, blood cultures, catheters, and urinary cultures.

SETTING

General intensive care unit.

PATIENTS

One hundred and thirty-two intensive care unit patients.

INTERVENTIONS

The antibiotics studied were amoxiclav, piperacillin-tazobactam, cefotaxime, ceftazidime, cefepim, and imipenem. The mechanisms of resistance studied were production of penicillinase or cephalosporinase, nonenzymatic mechanisms, and loss of porin OprD2. Analysis was performed using Cox proportional-hazard regression with time-dependant variables.

MEASUREMENTS AND MAIN RESULTS

Forty-two strains became resistant, 30 to one antibiotic, nine to two, and three to three, leading to the study of 57 resistant strains. Imipenem (hazard ratio 7.8; 95% confidence interval, 3.4-18.1), piperacillin-tazobactam (hazard ratio 3.9; 95% confidence interval, 1.3-11.9), and cefotaxim (hazard ratio 9.3; 95% confidence interval, 2.9-30.2) were strongly linked to the emergence of resistance. The use of imipenem (p<.0001) was associated with the loss of porin OprD2. Thirty-six strains from nine patients, assayed by pulsed-field gel electrophoresis, showed that for any one patient, all the strains were genetically related.

CONCLUSIONS

Our results show that there is a high risk of the emergence of drug resistance during treatment with cefotaxime, imipenem, and piperacillin-tazobactam. This has to be taken into account in the therapeutic choice and in the patient's surveillance.

Pneumonia due to Pseudomonas aeruginosa: the levofloxacin clinical trials experience

Respiratory infections caused by Pseudomonas aeruginosa present significant treatment challenges, including that of overcoming intrinsic and adaptive resistance by these organisms. The fluoroquinolones may provide an effective option for treating these infections. In this analysis, we report on the efficacy of levofloxacin in the treatment of community-acquired pneumonia (CAP) and nosocomial pneumonia caused by P. aeruginosa using information from nine clinical studies supported by Johnson & Johnson Pharmaceutical Research and Development (Raritan, NJ) or Ortho-McNeil Pharmaceutical (Raritan, NJ). From these studies, a total of 36 patients were identified with pneumonia caused by P. aeruginosa and treated with levofloxacin (750 mg or 500 mg). For patients diagnosed with nosocomial pneumonia, levofloxacin treatment achieved a 64.7% (11/17) clinical success rate, compared with 41.2% (7/17) with comparator treatment (imipenem/cilastatin followed by ciprofloxacin) in the microbiologically evaluable population. Eradication rates were 58.8% with levofloxacin treatment vs. 29.4% with comparator (95% CI, -64.2 to 5.4). For levofloxacin-treated CAP patients with P. aeruginosa infections (n = 19), clinical success and microbiological eradication rates in the microbiologically evaluable population were 89.5% and 78.9%, respectively. Several limitations of this analysis exist including that this was a retrospective evaluation that pooled data from multiple studies with varying protocols, the number of patients included was limited, and the nosocomial pneumonia patients used adjunctive therapy with an antipseudomonal beta-lactam in most cases. Nonetheless, these findings suggest that levofloxacin may play a role in the treatment of these difficult respiratory infections.

Contrôle de la source et antibiothérapie des infections graves

Source control and antimicrobial therapy together are the keys of successful treatment of sever infections. Source control may be surgical, radiological nor medical. Whatever the cause, drainage is the main important point. Antimicrobial therapy has to be introduced early in the course of infection, must be adequate, essentially with a broad spectrum and prescribed at the right dosage. Combination of antimicrobial therapy is more justified by broadening spectrum than for obtaining synergy.

Levofloxacin for treatment of ventilator-associated pneumonia: a subgroup analysis from a randomized trial

Ventilator-associated pneumonia (VAP) remains a significant challenge in critical care. We conducted a secondary analysis of a multicenter, prospective, randomized trial comparing levofloxacin (750 mg iv q24h) with imipenem-cilastatin (500-1000 mg iv q6-8h) for treatment of nosocomial pneumonia and focused on the subgroup of patients with VAP. The study cohort included 222 patients, with half (111) of the patients assigned to each treatment group. The patients in both groups were similar with respect to age, severity of illness, and duration of mechanical ventilation before the onset of VAP. Among the intention-to-treat population, clinical success was achieved in 58.6% of patients receiving levofloxacin, compared with 63.1% of patients receiving imipenem-cilastatin (P=.49; 95% confidence interval for the difference, -8.77% to 17.79%). Microbiological success and 28-day mortality rates were also comparable. Multivariate analysis demonstrated that assignment to antibiotic treatment (i.e., levofloxacin vs. imipenem-cilastatin) was not predictive of outcomes, thus suggesting that the treatment regimens were equivalent. Both levofloxacin and imipenem-cilastatin regimens were well tolerated and had similar adverse event profiles.

Quinolones for treatment of nosocomial pneumonia: a meta-analysis

Although quinolones are often used to treat nosocomial pneumonia (NP), there have been few trials documenting their efficacy in treating NP. Given the growing use of quinolones and issues regarding resistance, we conducted a meta-analysis of all trials of quinolones for treatment of NP. We identified 5 randomized trials comparing quinolones with other agents used to treat NP. The studies varied in both quality and sample size and included a total of nearly 1200 subjects. Four of the 5 trials used ciprofloxacin, administered every 8 h, whereas the fifth used levofloxacin administered daily. In 3 trials, the comparator agent was imipenem-cilistatin, whereas, in 2 trials, ceftazadime was the comparator agent. The efficacy of quinolones and comparator antibiotics was similar, with a pooled odds ratio for clinical cure of 1.12 (95% confidence interval, 0.80-1.55). Neither microbiological eradication rates nor mortality rates varied on the basis of antimicrobial selection.

The Crisis of Resistance: Identifying Drug Exposures to Suppress Amplification of Resistant Mutant Subpopulations

Antibiotic resistance is seen in both the hospital and community settings. Approaches are required to minimize the increase in resistant strains, such as good antibiotic stewardship and the limiting of antibiotic use to appropriate circumstances. There are instances when drug dose and/or schedule can be used to minimize the probability that mutants will take over the bacterial population. Over the past several years, significant advances have been made in understanding the relationship between drug concentrations and amplification of resistant mutant subpopulations. In this review, we examine the use of preclinical models for facilitating this understanding. We also use mathematical techniques, including Monte Carlo simulation, to bridge between the identification of exposures to minimize resistance and the examination of candidate drug doses to achieve this end. Examples are provided for Pseudomonas aeruginosa, Streptococcus pneumoniae, Staphylococcus aureus, and Mycobacterium tuberculosis. In each instance, quinolone antimicrobials were examined. More investigations with other pathogens and drug classes are required.

Use of Broad-Spectrum Antimicrobials for the Treatment of Pneumonia in Seriously Ill Patients: Maximizing Clinical Outcomes and Minimizing Selection of Resistant Organisms

Among various risk factors for death among critically ill patients with serious infection, inappropriate antimicrobial therapy is an important factor that clinicians can modify directly. The presence of multidrug-resistant bacteria is the primary reason that patients with ventilator-associated pneumonia receive inappropriate antimicrobial therapy. Empirical antimicrobial therapy for ventilator-associated pneumonia should be initiated promptly and should have a broad spectrum that covers all potential antimicrobial-resistant pathogens. Delaying the start of therapy or modifying an inappropriate antimicrobial regimen does not improve outcome, probably because the change comes too late to redirect the course of illness. Timely empirical therapy with highly effective agents that are rapidly bactericidal could minimize the emergence of resistance. Broad-spectrum therapy should be streamlined (i.e., de-escalated), as appropriate, on the basis of microbiological data and clinical response. Switching to narrower-spectrum therapy that is directed by culture results may minimize the emergence of resistance. For some patients, clinical response will allow a shortening of the duration of antimicrobial therapy.

Neumonía por Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of the leading causes of Gram-negative nosocomial pneumonia. It is the most common cause of ventilator-associated pneumonia and carries the highest mortality among hospital-acquired infections. P. aeruginosa produces a large number of toxins and surface components that make it especially virulent compared with other microorganisms. These include pili, flagella, membrane bound lipopolysaccharide, and secreted products such as exotoxins A, S and U, elastase, alkaline protease, cytotoxins and phospholipases. The most common mechanism of infection in mechanically ventilated patients is through aspiration of upper respiratory tract secretions previously colonized in the process of routine nursing care or via contaminated hands of hospital personnel. Intravenous therapy with an antipseudomonal regimen should be started immediately when P. aeruginosa pneumonia is suspected or confirmed. Empiric therapy with drugs active against P. aeruginosa should be started, especially in patients who have received previous antibiotics or present late-onset pneumonia.

Treatment and control of severe infections caused by multiresistant Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of the leading causes of nosocomial infections. Severe infections, such as pneumonia or bacteraemia, are associated with high mortality rates and are often difficult to treat, as the repertoire of useful anti-pseudomonal agents is limited (some beta-lactams, fluoroquinolones and aminoglycosides, and the polymyxins as last-resort drugs); moreover, P. aeruginosa exhibits remarkable ability to acquire resistance to these agents. Acquired resistance arises by mutation or acquisition of exogenous resistance determinants and can be mediated by several mechanisms (degrading enzymes, reduced permeability, active efflux and target modification). Overall, resistance rates are on the increase, and may be different in different settings, so that surveillance of P. aeruginosa susceptibility is essential for the definition of empirical regimens. Multidrug resistance is frequent, and clinical isolates resistant to virtually all anti-pseudomonal agents are increasingly being reported. Monotherapy is usually recommended for uncomplicated urinary tract infections, while combination therapy is normally recommended for severe infections, such as bacteraemia and pneumonia, although, at least in some cases, the advantage of combination therapy remains a matter of debate. Antimicrobial use is a risk factor for P. aeruginosa resistance, especially with some agents (fluoroquinolones and carbapenems), and interventions based on antimicrobial rotation and restriction of certain agents can be useful to control the spread of resistance. Similar measures, together with the prudent use of antibiotics and compliance with infection control measures, are essential to preserve the efficacy of the currently available anti-pseudomonal agents, in view of the dearth, in the near future, of new options against multidrug-resistant P. aeruginosa strains.

Ventilator-associated pulmonary infection: the germ theory of disease remains viable

Pulmonary infection complicating mechanical ventilation is a major problem in critical care. The key issues surrounding care of patients suspected of having this disease are 1) appropriate diagnostic criteria; 2) when antibiotic therapy should be started; and 3) what constitutes adequate antibiotic therapy. Current data support use of quantitative cultures obtained by either bronchoscopic or blind catheter lavage or mini-brushing. Antibiotic therapy should be guided by duration of hospitalization prior to presumed infection and local predominating nosocomial organisms and their microbial resistance patterns. The key issue with timing of therapy now centers around early termination of therapy if quantitative cultures are negative.

Fluid shifts have no influence on ciprofloxacin pharmacokinetics in intensive care patients with intra-abdominal sepsis

This study aimed to investigate whether fluid shifts alter ciprofloxacin pharmacokinetics in critically ill patients over time. Patients > or = 18 years, with normal renal function, requiring intensive care treatment and parenteral antibiotics were enrolled. Group A (22 patients) included patients with documented intra-abdominal infections. Group B (18 patients) included patients with severe sepsis from other causes. All patients received intravenous ciprofloxacin 400 mg every 8 h infused over 60 min. Eight timed blood specimens were taken on days 0, 2 and 7. Ciprofloxacin plasma concentrations were determined using high performance liquid chromatography. There were no significant differences between the pharmacokinetics of the two groups or over time. Ciprofloxacin pharmacokinetics in critically ill patients do not change over time, and intra-abdominal sepsis does not alter ciprofloxacin pharmacokinetic parameters to a greater degree than sepsis from other causes in critically ill patients.

Importance of adequate initial antimicrobial therapy

BACKGROUND

It has become an article of faith that appropriate antibiotic therapy is needed for best outcomes during a serious infection. Despite this long-held view, there is some debate about the role of appropriate outcome in serious infections, in particular with nosocomial pneumonia. Therefore, more recent data on adequacy of antibiotic therapy and outcomes were reviewed.

METHODS

The medical literature from 1997 to 2004 was surveyed for articles that directly dealt with appropriate therapy. Search terms included 'appropriate and inappropriate antibiotic therapy', 'adequate antibiotic therapy', 'resistance and antibiotic failures' and 'delayed therapy'. The data were abstracted to obtain their essential findings.

RESULTS

In bacteremia, data are most persuasive that appropriate and timely therapy significantly influences outcomes. Areas where this may not be the case are studies where coagulase-negative staphylococci are isolated in large numbers or in studies where the incidence of appropriate therapy is high. One area where data are not conclusive concerns the treatment of enteric bacteria carrying extended spectrum betalactamases, where the only cephalosporin of concern is ceftazidime. There is not enough data to compare carbapenems with specific cephalosporins to conclude that these are the most appropriate agents. The studies in regard to nosocomial pneumonias are not as conclusive as those with bacteremias. There appears to be a subset of patients that do not respond to therapy or do not survive, which confounds studies of this population; however, most studies favor a role of appropriate therapy.

CONCLUSIONS

Appropriate antibiotic therapy has several dimensions. It improves outcomes in most serious diseases. Timing of administration and appropriateness, based on susceptibility, are the most important determinants, but dosing intervals and dose probably play similarly important roles in outcomes that have not been examined exhaustively in humans. Other aspects of appropriate therapy that deserve attention include a shift to more 'resistance'-proof antibiotics in empiric therapy, which may be accompanied by better outcomes.

Empiric antibiotic coverage of atypical pathogens for community acquired pneumonia in hospitalized adults

BACKGROUND

Community acquired pneumonia (CAP) is caused by various pathogens, traditionally divided to 'typical' and 'atypical'. Initial antibiotic treatment of CAP is usually empirical, customarily covering both typical and atypical pathogens. To date, no sufficient evidence exists to support this broad coverage, while limiting coverage is bound to reduce toxicity, resistance and expense.

OBJECTIVES

Assess the efficacy and need of adding antibiotic coverage for atypical pathogens in hospitalized patients with CAP, in terms of mortality and successful treatment.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2005) which includes the Acute Respiratory Infection Group's specialized register; MEDLINE (January 1966 to January Week 2 2005); and EMBASE (January 1980 to January Week 2 2005).

SELECTION CRITERIA

Randomized trials of adult patients hospitalized due to CAP, comparing antibiotic regimens with atypical antibiotic coverage to a regimen without atypical antibiotic coverage.

DATA COLLECTION AND ANALYSIS

Two reviewers independently appraised the quality of each trial and extracted the data from included trials. Relative risks (RR) with 95% confidence intervals (CI) were estimated, assuming an intention-to-treat (ITT) basis for the outcome measures.

MAIN RESULTS

Twenty four trials were included, encompassing 5015 randomized patients. There was no difference in mortality between the atypical arm and the non-atypical arm (RR 1.13; 95% CI 0.82 to 1.54). The atypical arm showed an insignificant trend toward clinical success and a significant advantage to bacteriological eradication, which disappeared when evaluating methodologically high-quality studies alone. Clinical success for the atypical arm was significantly higher for Legionella pneumophilae (L. pneumophilae) and non-significantly lower for pneumococcal pneumonia. There was no significant difference between the groups in the frequency of (total) adverse events, or those requiring discontinuation of treatment. However, gastrointestinal events were more common in the non-atypical arm (RR 0.73, 95% CI 0.54 to 0.99).

AUTHORS' CONCLUSIONS

No benefit of survival or clinical efficacy was shown to empirical atypical coverage in hospitalized patients with CAP. This conclusion relates mostly to the comparison of quinolone monotherapy to non-atypical monotherapy. Further trials, comparing beta-lactam (BL) or cephalosporin therapy to BL or cephalosporin combined with a macrolide in this population, using mortality as its primary outcome, should be performed.

Therapeutic advances of new fluoroquinolones

Fluoroquinolone antimicrobials have been available for over 10 years. Recent modifications to nuclear side-chains have enhanced both the antimicrobial and pharmacokinetic profiles of this class. Rapidly increasing antimicrobial resistance among community and hospital bacterial pathogens has diminished therapeutic options. Infections caused by such pathogens, including drug-resistant Streptococcus pneumoniae and multi-resistant Enterobacteriaceae are now treatable by few classes of antibacterials, one of these being the fluoroquinolones. Ciprofloxacin was one of the first effective agents available in both iv. and oral formulations for the treatment of Gram-negative infection, resistant to other antibiotics. More recent developments, such as sparfloxacin and grepafloxacin, are more effective in vitro against Gram-positive pathogens, although their safety profile may be less promising. Fluoroquinolones not yet in widespread clinical use, including trovafloxacin, clinafloxacin and moxifloxacin, hold considerable promise as community 'respiratory antimicrobials' and the results of clinical trials are awaited with anticipation. In this review, the three generations of fluoroquinolone development are examined and the relative antimicrobial, pharmacokinetic, clinical and safety profiles of available and developmental quinolones are compared.

Antimicrobial therapy for patients with severe sepsis and septic shock: an evidence-based review

OBJECTIVE

In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for antimicrobial therapy for patients with severe sepsis and septic shock that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and improve outcome in severe sepsis.

DESIGN

The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee.

METHODS

The modified Delphi methodology used for grading recommendations built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591.

CONCLUSION

Since the prompt institution of therapy that is active against the causative pathogen is one of the most important predictors of outcome, clinicians must establish a system for rapid administration of a rationally chosen drug or combination of drugs when sepsis or septic shock is suspected. The expanding number of antibacterial, antifungal, and antiviral agents available provides opportunities for effective empiric and specific therapy. However, to minimize the promotion of antimicrobial resistance and cost and to maximize efficacy, detailed knowledge of the likely pathogens and the properties of the available drugs is necessary for the intensivist.

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

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

Persistent BBB disruption may underlie alpha interferon-induced seizures

Generalized seizures during Interferon-alpha (IFN-alpha) therapy have been repeatedly described in about 1%-4% of patients. However, the mechanisms underlying IFN-alpha induced seizures are not known. We describe a patient who developed partial and secondary generalized seizures during IFN-alpha therapy while displaying a focal disruption of her blood-brain barrier (BBB) corresponding with pathological electroencephalography (EEG). To test our hypothesis that IFN-alpha induces seizure activity, we exposed rat somatosensory cortices to clinically relevant concentrations of IFN-alpha in the acute in-vitro slice preparation or in-vivo. While acute exposure did not induce epileptic activity, recordings from slices exposed to IFN-alpha in-vivo one week prior to recordings revealed pronounced epileptiform activity in > 80% of the slices. We propose that cortical exposure to IFN-alpha leads to the generation of an epileptic cortex, which explains the weeks of latency in patients from initial treatment to seizures, and stressing the importance of identifying possible BBB disruption among high-risk patients administered peripherally acting drugs.

Clinical effect of intravenous ciprofloxacin on hospital-acquired pneumonia

The effect of intravenous ciprofloxacin (CPFX) on hospital-acquired pneumonia was examined. The subjects were 32 patients with hospital-acquired pneumonia classified as being in group I, group II, and group III, based on The Japanese Respiratory Society Guidelines for management of hospital-acquired pneumonia. None of the patients had received antibiotic treatment for the pneumonia. CPFX 300 mg was intravenously infused twice daily for 3-14 days, and its clinical effect, bacterological effect, and side effects were examined. Intravenous CPEX was clinically effective in 21 of the 32 patients, with an efficacy rate of 65.6%. With regard to bacteriological efficacy, 4 of 5 strains of methicillin-sensitive Staphylococcus aureus, 2 of 3 strains of Klebsiella pneumoniae, 1 of 2 strains of Streptococcus pneumoniae, 1 of 2 strains of Streptococcus agalactiae, 1 of 2 strains of Pseudomonas aeruginosa, 1 of 2 strains of Serratia marcescens, and the 1 strain of Klebsiella oxytoca were eradicated, with an eradication rate of 42.3% (11 of 26 strains whose fate was confirmed eradicated). Abnormal laboratory findings (side effects) were observed in 11 of the 32 patients (34.4%), but all side effects were mild. Based on the above data, intravenous CPFX may be the drug which should be recommended as the first choice for hospital-acquired pneumonia.

Healthcare-associated pneumonia in adults: management principles to improve outcomes

Guidelines for Management of HAP were developed jointly by the ATS and IDSA in 2004. These guidelines were designed to improve patient outcomes and to decrease the emergence of MDR pathogens (see Fig. 1).Principles include early initiation of appropriate and adequate antibiotic therapy after cultures of blood and sputum are obtained. Quantitative distal airway sampling by bronchoscopy provides greater diagnostic specificity for VAP: in one randomized study, improved outcomes were noted, compared with clinical diagnosis with qualitative endotracheal aspirates. Higher doses of initial, empiric antibiotics also are recommended. Assessment of the patient's clinical response to empiric antibiotics should be correlated with microbiologic results to streamline, de-escalate, or stop unnecessary anti-biotic treatment. Duration of therapy for uncomplicated HAP should be limited to 7 days followed by close monitoring for relapse after cessation of antibiotics. The authors suggest that prevention strategies target modifiable short- and long-term risk factors. They also advocate the use of a multidisciplinary team that is dedicated to the treatment and prevention of HCAP and the basic principle of the modern Hippocratic Oath: "I will prevent disease whenever I can, for prevention is preferable to cure."

Cefepime versus imipenem-cilastatin for treatment of nosocomial pneumonia in intensive care unit patients: a multicenter, evaluator-blind, prospective, randomized study

In a randomized, evaluator-blind, multicenter trial, we compared cefepime (2 g three times a day) with imipenem-cilastatin (500 mg four times a day) for the treatment of nosocomial pneumonia in 281 intensive care unit patients from 13 centers in six European countries. Of 209 patients eligible for per-protocol analysis of efficacy, favorable clinical responses were achieved in 76 of 108 (70%) patients treated with cefepime and 75 of 101 (74%) patients treated with imipenem-cilastatin. The 95% confidence interval (CI) for the difference between these response rates (-16 to 8%) failed to exclude the predefined lower limit for noninferiority of -15%. In addition, therapy of pneumonia caused by an organism producing an extended-spectrum beta-lactamase (ESBL) failed in 4 of 13 patients in the cefepime group but in none of 10 patients in the imipenem group. However, the clinical efficacies of both treatments appeared to be similar in a secondary intent-to-treat analysis (95% CI for difference, -9 to 14%) and a multivariate analysis (95% CI for odds ratio, 0.47 to 1.75). Furthermore, the all-cause 30-day mortality rates were 28 of 108 (26%) patients in the cefepime group and 19 of 101 (19%) patients in the imipenem group (P = 0.25). Rates of documented or presumed microbiological eradication of the causative organism were similar with cefepime (61%) and imipenem-cilastatin (54%) (95% CI, -23 to 8%). Primary or secondary resistance of Pseudomonas aeruginosa was detected in 19% of the patients treated with cefepime and 44% of the patients treated with imipenem-cilastatin (P = 0.05). Adverse events were reported in 71 of 138 (51%) and 62 of 141 (44%) patients eligible for safety analysis in the cefepime and imipenem groups, respectively (P = 0.23). Although the primary end point for this study does not exclude the possibility that cefepime was inferior to imipenem, some secondary analyses showed that the two regimens had comparable clinical and microbiological efficacies. Cefepime appeared to be less active against organisms producing an ESBL, but primary and secondary resistance to imipenem was more common for P. aeruginosa. Selection of a single agent for therapy of nosocomial pneumonia should be guided by local resistance patterns.

"Collateral damage" from cephalosporin or quinolone antibiotic therapy

"Collateral damage" is a term used to refer to ecological adverse effects of antibiotic therapy; namely, the selection of drug-resistant organisms and the unwanted development of colonization or infection with multidrug-resistant organisms. The risk of such damage can be assessed for different antibiotic classes by a variety of epidemiologic studies. Cephalosporin use has been linked to subsequent infection with vancomycin-resistant enterococci, extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, beta-lactam-resistant Acinetobacter species, and Clostridium difficile. Quinolone use has been linked to infection with methicillin-resistant Staphylococcus aureus and with increasing quinolone resistance in gram-negative bacilli, such as Pseudomonas aeruginosa. Neither third-generation cephalosporins nor quinolones appear suitable for sustained use in hospitals as "workhorse" antibiotic therapy.