Potential Impact of Vancomycin Pulmonary Distribution on Treatment Outcomes in Patients with Methicillin-ResistantStaphylococcus aureusPneumonia

Vancomycin as the drug of choice for treatment of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia has been called into question on the basis of therapeutic failures. In patients with MRSA pneumonia, treatment failures are probably due to the complex interplay of variables affecting the host-antimicrobial-pathogen interrelationship. However, it has been suggested that decreased penetration of vancomycin into the lungs may contribute. This review explores physiochemical and physiologic variables that affect pulmonary penetration and describes methods used in quantifying pulmonary vancomycin concentrations. Most important, findings are evaluated in the clinical context of the chemotherapeutic options available for treatment of MRSA pneumonia. The possibility of increased serum vancomycin concentrations as a method to optimize current treatment outcomes is also explored.

Post-MRSA infection glomerulonephritis with marked Staphylococcus aureus cell envelope antigen deposition in glomeruli

A 48-year-old male developed massive proteinuria and renal dysfunction after pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA) infection. Examination of a renal biopsy specimen by light microscopy showed severe mesangiocapillary proliferative glomerulonephritis with fibrocellular crescents. Immunofluorescence microscopy showed weak linear staining for immunoglobulin G (IgG), while both the peripheral and mesangial lesions stained for IgA and C3. Immunostaining for a possible antigen related to post-MRSA infection glomerulonephritis, using monoclonal antibody S1D6, revealed marked deposition of S.aureus cell envelope antigen in the glomeruli. Electron-dense deposits were observed in both the subendothelial and the mesangial areas. Focal subendothelial widening accompanied with monocytes or foam cell infiltration was also seen. The findings reflect a typical post-MRSA infection glomerulonephritis caused by S.aureus cell envelope antigen.

Efficacy of telavancin (TD-6424), a rapidly bactericidal lipoglycopeptide with multiple mechanisms of action, in a murine model of pneumonia induced by methicillin-resistant Staphylococcus aureus

The efficacy of telavancin, a bactericidal lipoglycopeptide, was compared to that of vancomycin and linezolid against methicillin-resistant Staphylococcus aureus (MRSA) in a murine pneumonia model. Telavancin produced greater reductions in lung bacterial titer and mortality than did vancomycin and linezolid at human doses equivalent to those described by the area under the concentration-time curve. These results suggest the potential utility of telavancin for treatment of MRSA pneumonia.

Evaluation of Clinical Efficacy of Maeda’s Nomogram for Vancomycin Dosage Adjustment in Adult Japanese MRSA Pneumonia Patients

The clinical efficacy of Maeda's nomogram for vancomycin dosage adjustment was evaluated by comparison with a standard dosage regimen (package insert information: vancomycin dose reduced in elderly patients and patients with renal dysfunction, with Moellering's nomogram used for renal-dysfunction patients) in adult Japanese MRSA pneumonia patients. Using Maeda's nomogram, the vancomycin dose is fixed at 1,000 mg while the dosing interval is varied in accordance with individual creatinine clearance. Using a standard dosage regimen, 5 patients out of 27 (18.5%) achieved target plasma levels of vancomycin (25-40 microg/mL for peak and 5-15 microg/mL for trough) within 2-6 days. Using Maeda's nomogram, 38 patients out of 53 (71.7%) achieved target levels in that time. A higher clinical response (complete resolution of all signs and symptoms of MRSA infection) to vancomycin therapy was also obtained with Maeda's nomogram when evaluated approximately 2-weeks after discontinuation of vancomycin therapy (43.4% versus 18.5% for the standard regimen). In conclusion, the Maeda's nomogram regimen with a 1,000 mg vancomycin dose was shown to achieve target plasma levels of vancomycin at a higher rate and provide higher clinical efficacy in vancomycin therapy of MRSA pneumonia patients, as compared with the currently available standard dosage regimen.

[Staphylococcus aureus: role and impact in the treatment of nosocomial pneumonia]

INTRODUCTION

Staphylococcus aureus (SA) has acquired a leading role in nosocomial pneumonia in terms of both frequency and severity, and poses therapeutic problems, namely antibiotic resistance and difficulties in the management of anti-staphylococcal drugs.

STATE OF THE ART

Epidemiological data confirm that SA is implicated in almost a quarter nosocomial pneumonias, of which about a half are due to methicillin resistant SA (MRSA) in France. The pathophysiology of these infections most often involves inhalation following oropharyngeal carriage. In addition to the risk factors common to all nosocomial pneumonias there are the particular roles of head injury and coma, leading to an increased frequency of SA infection in neuro-surgical patients.

PERSPECTIVES

The non-specific clinical picture, the grave prognosis of these pneumonias and the ineffectiveness against MRSA of the antibiotics used in the treatment of Gram negative infections make empirical treatment difficult.

CONCLUSION

In addition to the antibiotics classically active against SA (notably methicillin for sensitive strains and glycopeptides for MRSA) new agents may allow improvement in the treatment of these patients, even if their place is not yet definitively established.

Antibiotic management of ventilator-associated pneumonia due to antibiotic-resistant gram-positive bacterial infection

Gram-positive cocci, in particular Staphylococcus aureus, account for as much as one-third of all cases of hospital-acquired pneumonia, and treatment has become increasingly complex as the proportion of resistant isolates has increased. Methicillin-resistant S. aureus is of particular concern because this pathogen is now associated with hospital-acquired, ventilator-associated, community-acquired, and healthcare-associated pneumonia. Antibiotic therapy for ventilator-associated pneumonia is challenging because it can be caused by multiple pathogens, which can be resistant to multiple drugs. This article reviews the epidemiology of ventilator-associated pneumonia and describes options for antibiotic treatment. Particular attention is paid to pneumonia due to methicillin-resistant S. aureus. Studies suggest that vancomycin, the traditional treatment for ventilator-associated pneumonia, may not be the best option for this type of pneumonia and that other antibiotics, such as linezolid and clindamycin, might be better choices. New antibiotics with activity against methicillin-resistant S. aureus are under investigation and may soon become available for clinical use. Studies are needed to define the optimal choice of antibiotic for pneumonias caused by this organism, and these choices will need to be balanced with the need to minimize the emergence of resistance.

Neumonía nosocomial causada por Staphylococcus aureus resistente a meticilina

Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly common cause of hospital acquired pneumonia (HAP) and the second most frequently isolated pathogen from patients who die from HAP. High-risk units for MRSA colonization such as intensive care (ICU's) are the most affected. Multiple risk factors for transmission of MRSA have been identified, including colonization pressure and severity of illness at ICU admission. On the other hand, the most important predisposing factor for MRSA infection is prolonged mechanical ventilation and/or previous antibiotic therapy. Controlling the spread of MRSA remains a major challenge for hospitals. Screening programs, together with contact precautions for cases with MRSA and judicious antimicrobial use are major factors for a successful control. Early appropriate initial therapy is of crucial importance and improves outcome. The standard therapy has been glycopeptides but, in spite of its in vitro activity, mortality in critically ill patients treated with glycopeptides has consistently been reported high, mainly due to their poor lung penetration. Linezolid shows better clinical cure and survival rates, but further studies are needed. As the treatment options for MRSA pneumonia are limited and inadequate, development of more effective drugs is mandatory.

Enfoque clínico del paciente con neumonía asociada a ventilación mecánica

Ventilator-associated pneumonia (VAP) is the most frequent infection in the intensive care unit. The importance of this entity lies not only in its high incidence but also in the significant mortality it produces. Therefore, a new episode of VAP should be clinically suspected when new or persistent radiological opacity, purulent respiratory secretions and other signs of sepsis (fever and leukocytosis) are present. In these patients, at the very least, tracheal aspirate samples with quantitative culture and direct staining should be immediately obtained, followed by prompt initiation of empirical broad-spectrum antibiotic therapy. The choice of initial antibiotic therapy should be patient-based, taking into account the risk factors associated especially with VAP caused by Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus, because of the high associated mortality. To evaluate resolution of VAP, we analyze various clinical variables (based mainly on resolution of fever and hypoxemia) and microbiologic information. Once the microorganism responsible for VAP has been isolated, antibiotic therapy can be adapted, based on de-escalation, to reduce the emergence of resistant bacteria. Recent studies suggest that shorter antibiotic regimens reduce the emergence of antibiotic-resistant pathogens, cost and adverse events.

Favorable outcome of pneumonia due to Panton–Valentine leukocidin-producing Staphylococcus aureus associated with hematogenous origin and absence of flu-like illness

Reported here is what is believed to be the first case of community-acquired pneumonia caused by a Panton-Valentine leukocidin-producing strain of Staphylococcus aureus in Spain. Although lung infections caused by S. aureus strains carrying this powerful leukocidin gene are associated with necrotizing pneumonia and high mortality, the previously healthy 28-year-old male reported here experienced a good clinical course and recovery. It is thought that the hematogenous origin of the infection, the patient's lack of any previous respiratory viral infection and prompt initiation of therapy may explain the satisfactory evolution in this case.

Hypertonic saline dextran after burn injury decreases inflammatory cytokine responses to subsequent pneumonia-related sepsis

The present study examined the hypothesis that hypertonic saline dextran (HSD), given after an initial insult, attenuates exaggerated inflammation that occurs with a second insult. Adult rats (n = 15 per group) were divided into groups 1 (sham burn), 2 [40% total body surface area burn + 4 ml/kg isotonic saline (IS) + 4 ml.kg(-1).% burn(-1) lactated Ringer solution (LR)], and 3 (burn + 4 ml/kg HSD + LR), all studied 24 h after burns. Groups 4 (sham burn), 5 (burn + IS + LR), and 6 (burns + HSD + LR) received intratracheal (IT) vehicle 7 days after burns; groups 7 (burn + IS + LR) and 8 (burn + HSD + LR) received IT Streptococcus pneumoniae (4 x 10(6) colony-forming units) 7 days after burn. Groups 4-8 were studied 8 days after burn and 24 h after IT septic challenge. When compared with sham burn, contractile defects occurred 24 h after burn in IS-treated but not HSD-treated burns. Cardiac inflammatory responses (pg/ml TNF-alpha) were evident with IS (170 +/- 10) but not HSD (45 +/- 5) treatment vs. sham treatment (80 +/- 15). Pneumonia-related sepsis 8 days after IS-treated burns (group 7) exacerbated TNF-alpha responses/contractile dysfunction vs. IS-treated burns in the absence of sepsis (P < 0.05). Sepsis that occurred after HSD-treated burns (group 8) had less myocyte TNF-alpha secretion/better contractile function than IS-treated burns given septic challenge (group 7, P < 0.05). We conclude that an initial burn injury exacerbates myocardial inflammation/dysfunction occurring with a second insult; giving HSD after the initial insult attenuates myocardial inflammation/dysfunction associated with a second hit, suggesting that HSD reduces postinjury risk for infectious complications.

Epidemiology, treatment, and outcomes of nosocomial bacteremic Staphylococcus aureus pneumonia

OBJECTIVE

To describe outcomes associated with nosocomial bacteremic Staphylococcus aureus pneumonia (NBSAP) and to determine whether delay in adequate antimicrobial treatment is a risk factor for negative clinical and microbiological outcomes.

DESIGN

Retrospective cohort analysis.

SETTING

This study was conducted at Detroit Receiving Hospital and University Health Center, which is a 279-bed, level 1 trauma center in Detroit, MI.

PATIENTS

All episodes of NBSAP identified from January 1, 1999, to April 30, 2004.

RESULTS

Of 206 patients identified over a 5-year period with positive blood and respiratory cultures for S aureus, 60 patients met strict clinical, radiographic, and microbiological criteria for NBSAP. The overall mean (+/- SD) characteristics include the following: age, 55.5 +/- 15.0 years; acute physiology and chronic health evaluation II score, 20 (range, 3 to 41); ICU at onset, 93.3%; mechanical ventilation, 83.3%; length of stay (LOS) prior to NBSAP, 9 days (range, 2 to 81 days); methicillin-resistant S aureus (MRSA) rate, 70%; and all-cause hospital and infection-related mortality (IRM), 55.5% and 40.0%, respectively. Overall, S aureus pneumonia developed late in the patient's hospital stay in ICU patients previously receiving mechanical ventilation and was associated with high crude mortality and IRM rates. No significant difference existed with respect to mortality or infection-related LOS between patients who had received early appropriate antibiotic therapy vs those who had received delayed appropriate antibiotic therapy at the onset of pneumonia or in patients with methicillin-sensitive S aureus pneumonia vs those with MRSA pneumonia.

CONCLUSION

IRM from NBSAP is high, and standard therapies evaluated at the time of this study resulted in poor clinical outcomes. Delayed therapy was not found to be a predictor of adverse outcomes; however, this lack of ability to detect a difference may be a product of small sample size. These findings suggest that newer agents with enhanced clinical activity in NBSAP are needed and that these should be evaluated in a real-world setting, where outcomes of the most ill patients can be assessed.

Is Methicillin Resistance Associated with a Worse Prognosis in Staphylococcus aureus Ventilator-Associated Pneumonia?

BACKGROUND

Excess mortality associated with methicillin resistance in patients with Staphylococcus aureus ventilator-associated pneumonia (SA-VAP), taking into account such confounders as treatment adequacy and time in the intensive care unit (ICU), have not been adequately estimated.

METHODS

One hundred thirty-four episodes of SA-VAP entered in the Outcomerea database were studied. Patients from whom methicillin-resistant S. aureus (MRSA) was recovered were compared with those from whom methicillin-susceptible S. aureus (MSSA) was recovered, stratified for duration of stay in the ICU at the time of VAP diagnosis and adjusted for confounders (severity at admission, characteristics at VAP diagnosis, and treatment adequacy).

RESULTS

Treatment was adequate within 24 h after VAP diagnosis for 86% of the 65 MSSA-infected patients and 77% of the 69 MRSA-infected patients (P = .2). Polymicrobial VAP was more commonly associated with MSSA than with MRSA (49.2% vs. 25.7%; P = .01). MRSA infection was associated with a lower prevalence of coma at hospital admission and a higher rate of use of central venous lines and fluoroquinolones during the first 48 h of the ICU stay. The rates of shock, recurrence, and superinfection were similar in both groups. The crude hospital mortality rate was higher for MRSA-infected patients than for MSSA-infected patients (59.4% vs. 40%; P = .024). This difference disappeared after controlling for time in the ICU before VAP and parameters imbalanced at ICU admission (odds ratio [OR], 1.23; 95% confidence interval [CI], 0.49-3.12; P = .7) and remained unchanged after further adjustments for initial treatment adequacy and polymicrobial VAP (OR, 0.98; 95% CI, 0.36-2.66).

CONCLUSIONS

Differences in patient characteristics, initial ICU treatment, and time in the ICU confounded estimates of excess death due to MRSA VAP. After careful adjustment, methicillin resistance did not affect ICU or hospital mortality rates.

Fatal Community-Associated Methicillin-Resistant Staphylococcus aureus Pneumonia in an Immunocompetent Young Adult

Severe pneumonia caused by community-associated methicillin-resistant Staphylococcus aureus (MRSA) was reported in children soon after this pathogen emerged in the United States in the 1990s. Genes for Panton Valentine leukocidin, which are present in the majority of community-associated MRSA, are thought to enhance the ability of S aureus to cause necrotizing pneumonia. Despite the rapid spread throughout the United States of community-associated MRSA and related skin and soft-tissue infections, reports of severe pneumonia in adults have been rare. We describe a case of a healthy young adult who initially was treated as an outpatient with levofloxacin for what appeared to be typical community-acquired pneumonia. He soon returned to the emergency department (ED) with rapidly fatal necrotizing pneumonia, associated with hemoptysis, leukopenia, and sepsis syndrome, that was caused by community-associated MRSA carrying genes for Panton Valentine leukocidin. This case highlights the typical features of this form of pneumonia and the need to consider MRSA when evaluating and treating severe pneumonia in the ED. It also raises the question of whether the incidence of this form of pneumonia might be increasing in communities with a high prevalence of community-associated MRSA and whether current pneumonia treatment guidelines should be modified.

New recommendations for vancomycin dosage for patients with MRSA pneumonia with various degrees of renal function impairment

New recommendations for vancomycin (VCM) dosages and dosing intervals for MRSA-infected pneumonia patients with various degrees of renal function impairment were established based on Japanese population pharmacokinetic parameters proposed by Yasuhara et al. in 1998. Based on individual creatinine clearance (CLcr), we proposed the optimum VCM dosages and dosing intervals so that the peak level of VCM (level at 1 h after the end of infusion) is maintained in the range of 25-40 microg/ml and the trough level is kept under 15 microg/ml. The recommended doses and intervals of VCM were as follows: 20 mg/kg every 12 h for CLcr of 80-100 ml/min, 18 mg/kg every 12 h for CLcr of 70 ml/min, 25 mg/kg every 24 h for CLcr of 50-60 ml/min, 22 mg/kg every 36 h for CLcr of 40 ml/min, and 18 mg/kg every 48 h for CLcr of 30 ml/min. Using the recorded pharmacokinetic parameters of VCM from eight patients with pneumonia who were admitted to Aoyama Second Hospital between November 1997 and January 2002, these recommendations were used in computer simulations for the eight patients, and the usefulness of these recommendations was confirmed.

Fatal sepsis and necrotizing pneumonia in a child due to community-acquired methicillin-resistant Staphylococcus aureus: case report and literature review

Pediatric deaths due to community-acquired methicillin-resistant Staphylococcus aureus are rare. We describe the case of 2-y-old boy with fever and cough followed by comatose state with deteriorated respiration; the boy died of severe sepsis and necrotizing pneumonia. The etiological agent was community-acquired methicillin-resistant Staphylococcus aureus, carrying a type IV staphylococcal mecA gene cassette and the Panton-Valentine Leukocidin gene.

Pneumonia caused by oxacillin-resistant Staphylococcus aureus treated with glycopeptides*

OBJECTIVE

To determine whether ventilator-associated pneumonia caused by oxacillin-resistant Staphylococcus aureus (VAP-ORSA) treated with glycopeptides is associated with an increased mortality rate.

DESIGN

Retrospective matched cohort study.

SETTING

Four intensive care units in teaching hospitals.

PATIENTS

Seventy-five patients were matched to 75 controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All adult intensive care unit patients with microbiologically documented VAP-ORSA were matched to intubated controls who did not develop VAP-ORSA, based on disease severity (Acute Physiology and Chronic Health Evaluation II score) at admission (+/-3 points), diagnostic category, and length of stay before pneumonia onset. Population characteristics and intensive care unit mortality rates of patients with VAP-ORSA and their controls without pneumonia were compared. Attributable mortality was determined by subtracting the crude mortality rate of controls from the crude mortality rate of VAP-ORSA patients. Thirty-six of the 75 matched VAP-ORSA patients died, representing a crude mortality rate of 48%, whereas 19 of the 75 controls died, a crude mortality rate of 25.3% (p < .01). Excess mortality was estimated to be 22.7% (95% confidence interval, 2.4-42.9%). Median length of intensive care unit stay in the surviving pairs was 33 days (interquartile range, 25-75%: 25-45 days) for VAP-ORSA patients and 21 days (interquartile range, 25-75%: 15-34.75 days) days for controls (p = .054).

CONCLUSIONS

Despite appropriate glycopeptide therapy, there is an increased attributable mortality for pneumonia by ORSA, after careful adjustment for disease severity and diagnostic category.

[Hematogenous sternal osteomyelitis and community acquired pneumonia in a methicillin-susceptible Staphilococcus aureus sepsis]

We report here a case of primary haematogenous osteomyelitis diagnosed in a young mild asthmatic male with immunocompetence. A hard job worked as trigger of the septic picture from a forunculosis lesion located on the abdominal wall. Meticilin-susceptible Staphylococcus aureus was isolated from blood cultures and from sternal aspiration liquid. Two months after clinical onset Ig G 4 elevation was achieved at the immunodeficiency screening. Stafilococycal lung CT images accompanied to the septic course. Intravenous cloxacilin and gentamycin treatment followed by oral rifampicin and levofloxacin achieved a total recovery.

Cost-effectiveness of linezolid versus vancomycin in mechanical ventilation-associated nosocomial pneumonia caused by methicillin-resistant staphylococcus aureus

Linezolid, an oxazolidinone-class antimicrobial agent, is a new drug; its use has frequently been questioned due to its high price. However, recent trials have demonstrated that the use of linezolid in mechanical ventilation-associated nosocomial pneumonia caused by methicillin-resistant Staphylococcus aureus (VAP-MRSA) may be justified due to its improved efficacy compared to vancomycin. Price and cost have different magnitudes, and clinical efficacy should always be considered in the decision-making process. Our objective was to determine whether linezolid treatment was more cost-effective than vancomycin for treating VAP-MRSA.

METHODOLOGY

Elaboration of an economic model from a metanalysis of previous clinical trials comparing both drugs, through a cost-effectiveness analysis. Costs of the treatments were calculated using Brazilian parameters and were compared to the results obtained in the metanalysis. In order to compare the results with real life conditions, costs were calculated for both name brand and for generic vancomycin.

RESULTS

The cost (May/2004) per unit (vial, ampoule or bag) was R$ 47.73 for the name-brand vancomycin, R$ 14.45 for generic vancomycin and R$ 214.04 for linezolid. Linezolid's efficacy in VAP-MRSA according to the metanalysis was 62.2% and vancomycin's efficacy was 21.2%. The total cost per cured patient was R$ 13,231.65 for the name-brand vancomycin, R$ 11,277.59 for generic vancomycin and R$ 7,764.72 for linezolid.

CONCLUSION

Despite the higher price per unit, linezolid was more cost-effective than vancomycin.

[Experimental study on the therapeutic effect of liposome-entrapped antibiotics in the treatment of destructive pneumonia]

The data on preparation of liposome-entrapped gentamicin sulfate and cefoperazone and their investigation on albino mice with staphylococcal destructive pneumonia are presented. Comparative study of the efficacy of gentamicin sulfate and cefoperazone in free and liposome-entrapped forms showed that immobilization of the antibiotics in phospholipid vesicles provided a 2-fold increase of their efficacy.

Emerging issues in the diagnosis and management of infections caused by multi-drug-resistant, gram-positive cocci

BACKGROUND

Rising rates of multi-drug-resistant, gram-positive cocci (e.g., methicillin-resistant Staphylococcus aureus [MRSA], vancomycin-resistant Enterococcus spp. [VRE]) have created treatment challenges for clinicians in both the hospital and community settings. These organisms have become especially problematic for hospitalized patients with pneumonia, complicated intra-abdominal infections, and skin and skin-structure infections (SSSIs).

METHODS

A review of the recent literature (1990 onwards) was undertaken in order to review the epidemiology, diagnostic issues, and clinical trial data of available and forthcoming therapies for the treatment of multi-drug resistant, gram-positive isolates, with an emphasis on selected MRSA infections (i.e., pneumonia, SSSI, diabetic foot infections, blood stream) and infections caused by VRE.

RESULTS

The rate of healthcare-associated MRSA in 2004 rose to an incidence of 59.5% in the United States compared with data from 1998-2002, making MRSA the predominant gram-positive etiology of S. aureus infections in hospitalized patients. Methicillin-resistant S. aureus has also emerged as an important pathogen in both the non-ICU and community settings. Similarly, 28.5% of all enterococcal isolates were identified as vancomycin-resistant in 2003 (a 12% increase). However, these rates may be underestimated, as detection methods for determining susceptibility have proved to be inadequate. Recognition that prior inadequate antibiotic therapy is common in patients with antibiotic-resistant bacteria, and is associated with higher mortality rates, emphasizes the importance of selecting appropriate empiric therapy. Currently available therapies for resistant gram-positive infections include quinupristin-dalfopristin, linezolid, and daptomycin, although each of these agents has limitations (e.g., daptomycin is not indicated for MRSA pneumonia due to inadequate lung tissue penetration and inactivation by surfactant). Three agents with broad-spectrum activity against gram-positive organisms that are at an advanced stage of testing include two new glycopeptides (oritavancin and dalbavancin), and a first-in-class glycylcycline (tigecycline). These agents have demonstrated efficacy in the treatment of SSSIs, including those caused by MRSA.

CONCLUSIONS

New antimicrobial agents are needed to combat the increasing prevalence of multi-drug-resistant, gram-positive pathogens such as MRSA. The emergence of resistance to available therapies such as vancomycin underscores this urgency.

[Guidelines for treatment of pneumonia in intensive care units]

Patients affected by pneumonia can be admitted in Intensive Care Units (ICUs) independently by the setting where the infection has been acquired (community, hospital, long-term care facilities); even more frequently pneumonia can develop in patients already hospitalized in ICU especially in those requiring mechanical ventilation for different reasons. Within the severe community acquired pneumonia requiring admission in ICU, the most frequently responsible micro-organisms are mainly represented by Streptococcus pneumoniae, but also by Legionella and Haemophilus. Pseudomonas aeruginona, anyway, cannot be excluded. The most recent Canadian and American guidelines for treatment of the above mentioned infections suggest the use of a combination therapy with beta-lactams (ceftriaxone, cefotaxime, ampicillin/sulbactam, piperacillin/tazobactam) and a new generation macrolide or respiratory fluoroquinolone. In case of allergy to beta-lactams, the association fluoroquinolone-clindamycin should be preferred. Whenever a Pseudomonas etiology is suspected because of the presence of risk factors such as COPD, cystic fibrosis, bronchiectasis, previous and/or frequent therapies with antibiotics and/or steroids, the same guidelines suggest the use of an anti-pseudomonas beta-lactam (such as piperacillin/tazobactam, carbapenems, cefepime) associated with an anti-pseudomonas fluoroquinolone (high doses ciprofloxacin). An anti-pseudomonas beta-lactam plus an aminoglycoside or aminoglicosyde plus fluoroquinolone can be an alternative. Early onset Hospital Acquired Pneumonia (HAP) and early onset Ventilator Associated Pneumonia (VAP) in patients without risk factors for multi-resistant etiological agents are generally sustained by S. pneumoniae, H. influenzae, methicillin-susceptible Staphylocccus aureus e Gram negative enteric rods. These infections can be treated with one of the following antibiotics: ceftriaxone or fluoroquinolones (moxifloxacin or ciprofloxacin or levofloxacin) or ampicillin/sulbactam or ertapenem. Late onset VAP and HAP in patients with risk factors for multi-resistant, by contrast, should be treated with a combination therapy: in case of defined or suspected P. aeruginosa, Klebsiella pneumoniae (ESbL+), Acinetobacter sp etiology, it is required the use of an anti-pseudomonas cephalosporin or an anti-pseudomonas carbapenem or b-lactam + beta-lactamase inhibitor associated with an anti-pseudomonas fluoroquinolone or an aminoglicoside. The possible presence of MRSA or Legionella pneumophila suggests the use of anti-Gram positive antibiotics such as glycopeptides or linezolid. These quidelines confirm the role of ciprofloxacin combined with beta-lactams whenever P. aeruginosa, Klebsiella pneumoniae (ESbL+), Acinetobacter sp. etiology is suspected.

Efficacy of Quinupristin-Dalfopristin against Methicillin-Resistant Staphylococcus aureus and Vancomycin-Insensitive S. aureus in a Model of Hematogenous Pulmonary Infection

BACKGROUND

Quinupristin-dalfopristin (Q-D) is a mixture of quinupristin and dalfopristin, which are semisynthetic antibiotics of streptogramin groups B and A, respectively.

METHODS

We compared the effect of Q-D to that of vancomycin (VCM) in murine models of hematogenous pulmonary infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and VCM-insensitive S. aureus (VISA).

RESULTS

Treatment with Q-D resulted in a significant decrease in the number of viable bacteria in the lungs of mice in an MRSA infection model [Q-D 100 mg/kg, Q-D 10 mg/kg, VCM and control (mean +/- SEM): 2.99 +/- 0.44, 6.38 +/- 0.32, 5.75 +/- 0.43 and 8.40 +/- 0.14 log10 CFU/lung, respectively]. Compared with VCM, high-dose Q-D significantly reduced the number of bacteria detected in the VISA hematogenous infection model [Q-D 100 mg/kg, Q-D 10 mg/kg, VCM and control (mean +/- SEM): 5.17 +/- 0.52, 7.03 +/- 0.11, 7.10 +/- 0.49 and 7.18 +/- 0.36 log10 CFU/lung, respectively]. Histopathological examination confirmed the effect of Q-D.

CONCLUSION

Our results suggest that Q-D is potent and effective in the treatment of MRSA and VISA hematogenous pulmonary infections.

Impact of Methicillin Resistance on Outcome ofStaphylococcus aureusVentilator-associated Pneumonia

The impact of methicillin resistance on morbidity and mortality of patients suffering from severe Staphylococcus aureus infections remains highly controversial. We analyzed a retrospective cohort of 97 patients with methicillin-susceptible and 74 patients with methicillin-resistant Staphylococcus aureus ventilator-associated pneumonia (VAP). Initial empiric antibiotic therapy was appropriate for every patient. Patients with methicillin-resistant Staphylococcus aureus VAP were older, had higher disease-severity scores, and had been on mechanical ventilation longer at onset of VAP. Factors associated with 28-day mortality retained by multivariate logistic regression analysis were: age (odds ratio [OR] = 1.05, 95% confidence interval [CI], 1.02-1.08, p = 0.001) and Day 1 organ dysfunctions or infection (ODIN) score (OR = 1.90, 95% CI, 1.31-2.78, p = 0.001), but not methicillin resistance (OR = 1.72, 95% CI, 0.73-4.05, p = 0.22). The percentages of infection relapse or superinfection did not differ significantly between the two patient groups. In conclusion, after controlling for clinical and physiologic heterogeneity between groups, methicillin resistance did not significantly affect 28-day mortality of patients with Staphylococcus aureus VAP receiving appropriate antibiotics.

[Effect of adenosine on activity of transcription factor NF-kappa B and cytokines in myocardial tissue of experimental rats with pneumonia]

OBJECTIVE

Recent studies have shown that cytokines TNF-alpha and IL-6 play important roles in myocardial injury or dysfunction. Transcription nuclear factor (NF-kappa B) have been implicated in the regulation of a variety of cytokines in response to cellular defense. The authors observed the activity of NF-kappa B and cytokines TNF-alpha, IL-6 mRNA expression in myocardium to further investigate the mechanism of myocardial injury caused by infectious pneumonia. The therapeutic effect of exogenous adenosine was also studied by observing the influence on NF-kappa B and cytokines.

METHODS

Thirty rats were divided into three experimental groups at random, each group had 10 rats. The model of pneumonia was induced by the injection of Staphylococcus aureus into the trachea of rats. Adenosine-treated rats were given daily slow intravenous injection of adenosine at a dose of 150 microg/kg.min for 3 days from the second day. All rats were killed on the fifth day. Myocardial tissues were preserved in liquid nitrogen for examination. Pathological examination of myocardium was done and TNF-alpha and IL-6 mRNA expression was detected by reverse transcription polymerase chain reaction (RT-PCR). NF-kappa B activity was measured by electrophoretic mobility shift assay (EMSA).

RESULTS

(1) The myocardium in pneumonia group showed significant pathological lesion when compared with control group (P < 0.01). The pathological lesion of myocardium in adenosine-treated group significantly decreased when compared to pneumonia group (P < 0.05). (2) Significant increase of TNF-alpha and IL-6 mRNA expression was observed in myocardium of pneumonic rats when compared with control group (2.27 +/- 0.27 vs. 1.05 +/- 0.16; 1.89 +/- 0.31 vs. 1.12 +/- 0.25: P < 0.01, respectively). NF-kappa B activity of myocardium in pneumonia group was significantly higher than that in control group (13,033 +/- 1286 vs. 383 +/- 15: P < 0.01). (3) TNF-alpha and IL-6 mRNA expression was significantly decreased in adenosine-treated group when compared with pneumonia group (1.25 +/- 0.18 vs. 2.27; 1.31 +/- 0.25 vs. 1.89 +/- 0.31, P < 0.01, respectively). Comparing to that in pneumonia group, NF-kappa B activity of myocardium in adenosine-treated group was significantly decreased (4 487 +/- 562 vs. 13033 +/- 1286, P < 0.01), but it was still significantly higher than that in control group (4487 +/- 562 vs.383 +/- 15, P < 0.01).

CONCLUSIONS

Increased activity of NF-kappa B and subsequent upregulation of TNF-alpha and IL-6 mRNA expression probably play a pivotal role in the mechanism of myocardial injury in rats with pneumonia. Exogenous adenosine can inhibit inflammatory change by lowering NF-kappa B activity and subsequent down-regulation of TNF-alpha and IL-6 expression. Our findings provide novel therapeutic evidence of adenosine in myocardial injury induced by pneumonia in clinic.

Relationship between Fluoroquinolone Area under the Curve:Minimum Inhibitory Concentration Ratio and the Probability of Eradication of the Infecting Pathogen, in Patients with Nosocomial Pneumonia

Our objective was to prospectively determine the factors influencing the probability of a good microbiological or clinical outcome in patients with nosocomial pneumonia treated with a fluoroquinolone. Levofloxacin was administered as an infusion of 500 mg/h for 1.5 h (total dose, 750 mg). For patients with Pseudomonas aeruginosa or methicillin-resistant Staphylococcus aureus, a second drug was added (ceftazidime or piperacillin/tazobactam for P. aeruginosa and vancomycin for methicillin-resistant S. aureus). Population pharmacokinetic studies of 58 patients demonstrated that this population handled the drug differently from populations of volunteers. Multivariate logistic regression analysis (n=47 patients) demonstrated that only the age of the patient and the achievement of an area under the curve: minimum inhibitory concentration ratio of > or =87 had a significant effect on eradication of the pathogen (P<.001). Achieving the breakpoint made the patient 4 times more likely to achieve eradication. The effect was greatest in patients > or =67 years old.

Linezolid for treatment of ventilator-associated pneumonia: A cost-effective alternative to vancomycin*

OBJECTIVES

To determine the incremental cost-effectiveness of linezolid compared with vancomycin for treatment of ventilator-associated pneumonia due to Staphylococcus aureus.

DESIGN

Decision model analysis of the cost and efficacy of linezolid vs. vancomycin for treatment of ventilator-associated pneumonia. The primary outcome was the incremental cost-effectiveness of linezolid in terms of cost per added quality-adjusted life-year gained. Other outcomes were the marginal costs per hospital survivor and per year of life saved generated by using linezolid. Model estimates were derived from prospective trials of linezolid for ventilator-associated pneumonia and from other studies describing the costs and outcomes for ventilator-associated pneumonia.

SETTING AND PATIENTS

Hypothetical cohort of 1,000 patients diagnosed with ventilator-associated pneumonia.

INTERVENTIONS

In the model, patients received either linezolid or vancomycin.

MEASUREMENTS AND MAIN RESULTS

The incremental cost-effectiveness of linezolid was calculated as the additional quality-adjusted life-years resulting from therapy with linezolid divided by the sum of the incremental costs arising because of use of linezolid (e.g., higher direct costs for linezolid, costs per in-hospital care of survivors, and posthospitalization costs). Despite its higher cost, linezolid was cost-effective for treatment of ventilator-associated pneumonia. The cost per quality-adjusted life-year equals approximately 30,000 dollars. The model was moderately sensitive to the estimated efficacy of linezolid over vancomycin. Nonetheless, even with all inputs simultaneously skewed against, linezolid remains a cost-effective option (cost per quality-adjusted life-year approximately 100,000 dollars). Based on Monte Carlo simulation, the results of our analysis are robust across a range of model inputs and assumptions (95% confidence interval for cost per quality-adjusted life-year ranges from 23,637 dollars to 42,785 dollars).

CONCLUSIONS

Linezolid is a cost-effective alternative to vancomycin for the treatment of ventilator-associated pneumonia.

[Staphylococcal pneumonia]

In January to December 2000, a total of 15 (8.8%) patients with staphylococcal community-acquired pneumonia (CAP), 13 (27.7%) patients with staphyloccocal nosocomial pneumonia (NP) that occurred at general units (GU), and 9 (50%) patients with GU that occurred under artificial ventilation (AV) at intensive care units (ICU) were followed up. Meticillin-resistant S. aureus strains were isolated in 6.7, 38.5, and 55.6% of cases, respectively. As compared with pneumococcal CAP, staphyloccocal CAP were more frequently characterized by the severe course of the disease (46.7% versus 15.4%), bilateral lesion (33.3% versus 5.1%), and the presence of complications (66.7% versus 30.8%). Staphyloccocal NP that had occurred at GU, as compared to that at ICU also showed the severe course of the disease (46.2% versus 2.9%), bilateral lesion (30.7% versus 0%), and developed complications (75% versus 25%). Staphylococcal NP developed under AV at ICU had no specific features as compared with NP of another etiology. Oxacillin and first-second-generation cephalosporins remain to be the drugs of choice when meticillin-sensitive S. aureus strains are isolated; lincomycin and erythromycin being alternative agents against these strains. Glycopeptides are the drugs of choice when meticillin-resistant S. aureus strains are isolated, its alernatives are linesolide or rifampicin. High mortality rates due to staphylococcal pneumonia are preserved. These are 7.1% in CAP, 7.7 and 66.7 in staphylococcal NP occurring at GU and under AV at ICU, respectively.

Linezolid vs vancomycin: analysis of two double-blind studies of patients with methicillin-resistant Staphylococcus aureus nosocomial pneumonia

OBJECTIVE

To assess the effect of baseline variables, including treatment, on outcome in patients with nosocomial pneumonia due to methicillin-resistant Staphylococcus aureus (MRSA).

DESIGN

Retrospective analysis of data from two prospective, randomized, double-blind studies.

SETTING

Multinational study with 134 sites.

PATIENTS

A total of 1,019 patients with suspected Gram-positive nosocomial pneumonia, including 339 patients with documented S aureus pneumonia (S aureus subset) and 160 patients with documented MRSA pneumonia (MRSA subset).

INTERVENTIONS

Linezolid, 600 mg, or vancomycin, 1 g, q12h for 7 to 21 days, each with aztreonam.

MEASUREMENTS AND RESULTS

Outcome was measured by survival and clinical cure rates (assessed 12 to 28 days after the end of therapy). Logistic regression analysis was used to determine the effect of treatment and other baseline variables on outcome. Kaplan-Meier survival rates for linezolid vs vancomycin were 80.0% (60 of 75 patients) vs 63.5% (54 of 85 patients) for the MRSA subset (p = 0.03). Logistic regression analysis confirmed that the survival difference favoring linezolid remained significant after adjusting for baseline variables (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.0 to 4.8; p = 0.05). Other baseline variables associated with significantly higher survival rates in MRSA pneumonia were serum creatinine levels less than or equal to two times the upper limit of normal and absence of cardiac comorbidities. Clinical cure rates for linezolid vs vancomycin (excluding indeterminate or missing outcomes) were 59.0% (36 of 61 patients) vs 35.5% (22 of 62 patients) for the MRSA subset (p < 0.01). Logistic regression analysis confirmed that the difference favoring linezolid remained significant after adjusting for baseline variables (OR, 3.3; 95% CI, 1.3 to 8.3; p = 0.01). Other baseline variables associated with significantly higher clinical cure rates in MRSA pneumonia were single-lobe pneumonia, absence of ventilator-associated pneumonia, and absence of oncologic and renal comorbidities.

CONCLUSIONS

In this retrospective analysis, initial therapy with linezolid was associated with significantly better survival and clinical cure rates than was vancomycin in patients with nosocomial pneumonia due to MRSA.

Delayed recovery associated with persistent serum concentrations after clozapine overdose

Experience with managing overdoses of the atypical antipsychotic agent, clozapine, has been limited. A 20-year-old woman, who presented 6 h after ingesting 3500 mg of clozapine, had an unexpectedly prolonged duration of tachycardia and somnolence. Successful recovery followed management with supportive measures for several days in the intensive care unit. However, the duration of symptoms greatly exceeded that predicted by the published 12-h half-life of clozapine and was associated with an unexplained persistence of serum clozapine concentrations. Recovery with normalization of autonomic function occurred only after serum clozapine began to decline again after a 4-day plateau, as revealed by serum monitoring. Similar observations have been reported in two other cases. In overdose, clozapine may not behave as predicted by its published pharmacokinetics. Persistent serum drug concentrations may prolong the period of intensive care, suggesting that aggressive measures to remove clozapine from the gut at the time of overdose may be warranted.

[The impact of antibiotic use on hospital-acquired pneumonia: data of etiology tests]

AIM OF THE STUDY

To investigate most common pathogens isolated from the hospital-acquired pneumonia patients bronchoalveolar lavage fluid in Kaunas University of Medicine Hospital according to the previous antibiotic use and to estimate pathogens antibacterial susceptibility.

MATERIALS AND METHODS

Results of 87 hospital-acquired pneumonia patients bronchoalveolar lavage fluid quantitative cultures were analyzed. Microorganisms isolated in clinically significant amount were considered as the etiological agents and included into analysis. Susceptibility was tested using the standard methods. Previously untreated patients were considered if the antibacterials were not administered at all or were used less than for 24 hours.

RESULTS

H. influenzae isolation in significant amount rates were higher in previously untreated patients group comparing to previously treated (29.2%. (n=14) and 5.1% (n=2), respectively, p<0.05). Non-fermenters (P. aeruginosa and Acinetobacter spp.) isolation rates were higher in those previously treated comparing to untreated patients - (31.0% (n=13) and 4.2% (n=2), respectively, p<0.05). All H. influenzae strains were susceptible to ampicillin and cefuroxime. 22.2-44.4% of P. aeruginosa strains were resistant to ceftazidime, amikacin and ciprofloxacin. Estimated Acinetobacter spp. resistance to ciprofloxacin and gentamycin was 83.3% and to ampicillin/sulbactam - 16.7%. All methicillin-susceptible S.aureus were also susceptible to gentamycin and fucidin and methicillin resistant to rifampicin and vancomycin.

CONCLUSIONS

Previous antibiotic treatment has an impact on pneumonia etiology testing. H. influenzae strains are more common isolated hospital-acquired pneumonia etiologic agents in previously untreated patients. The low antibacterial resistance was found enabling the use of aminopenicillins for treatment if H. influenzae infection suggested. The use of antibacterials increases non-fermenters isolation rates and combined antipseudomonal treatment is reasonable in these patients.

Staphylococcus aureus bacteremic pneumonia: differences between community and nosocomial acquisition

OBJECTIVE

The aim of the study was to ascertain the clinical and epidemiologic characteristics of patients with nosocomial or community-acquired Staphylococcus aureus bacteremic pneumonia.

METHODS

A prospective study of 134 cases diagnosed between January 1990 and December 1995 was performed.

RESULTS

Fifty cases involved primary bacteremic pneumonias, of which 80% were nosocomial (the majority, 72%, in intensive care unit patients, of whom 57% were post-surgery). Of the 84 cases of secondary pneumonia, 36 were non-intravenous drug users (78% nosocomial, of whom 43% were in the intensive care unit), and 48 cases were intravenous drug users (98% community-acquired).

CONCLUSIONS

Nosocomial S. aureus bacteremic pneumonia was especially frequent in intensive care unit patients (68.1%), and community-acquired pneumonia in intravenous drug users (72.3%). In non-intravenous drug users, clinical outcome and mortality were similar for nosocomial and community-acquired pneumonia.

Clinical failure of vancomycin treatment of Staphylococcus aureus infection in a tertiary care hospital in southern Brazil

We describe a case of clinical failure of vancomycin treatment of Staphylococcus aureus infection and the laboratory characteristics of the organism in a tertiary referral university hospital in southern Brazil. An 11-month-old male patient presented with pneumonia and S. aureus was isolated from his respiratory tract. Initial treatment with oxacillin and gentamicin was ineffective. Vancomycin was added to the regimen as the patient worsened, but after the 30(th) day of vancomycin treatment S. aureus was isolated from the blood. This isolate had a minimum inhibitory concentration (MIC) for vancomycin of 4 mg/mL. After pre-incubation with vancomycin the isolate displayed an increase in the expression of vancomycin resistance and colonies grew in the presence of up to 12 mg/mL vancomycin. Based on these results, and considering that the patient had not responded to vancomycin, the isolate was considered to be S. aureus heteroresistant to vancomycin (SAHV). The SAHV proved to be similar, based on DNA macrorestriction analysis, to methicillin resistant S. aureus (MRSA) isolates from other patients in the hospital who had responded to vancomycin treatment. Our findings underline the need to improve methods in the clinical laboratory to detect the emergence of S. aureus clinically resistant to vancomycin. The fact that the isolate emerged in the blood 30 days after vancomycin treatment was initiated suggests that the organism was originally an MRSA that had acquired the ability to circumvent the mechanism of action of vancomycin.

Toxic shock syndrome in a horse with Staphylococcus aureus pneumonia

A 3-year-old Thoroughbred gelding was examined because of clinical signs of pneumonia and shock. Mucous membrane petechiation and ventral edema were observed and considered to be a result of vasculitis. Epidermal necrosis developed on the distal portions of the limbs. The horse had a persistent high fever that was unresponsive to nonsteroidal anti-inflammatory treatment, and Staphylococcus aureus was isolated from a nasal swab specimen and 2 transtracheal wash fluid samples. Antimicrobial, anti-inflammatory, and supportive treatment resulted in clinical improvement. However, resolution of the pulmonary infection required long-term (42 days) antimicrobial administration. Staphylococcus aureus strains isolated from this horse were positive for the toxic shock syndrome toxin-1 gene and were shown to produce toxic shock syndrome toxin-1, the causative factor in toxic shock syndrome in humans. The horse's clinical signs were attributed to toxic shock syndrome secondary to pulmonary S. aureus infection.

Levofloxacin compared with imipenem/cilastatin followed by ciprofloxacin in adult patients with nosocomial pneumonia: a multicenter, prospective, randomized, open-label study

BACKGROUND

Therapy of nosocomial pneumonia is usually empiric and includes > or = 1 broad-spectrum antimicrobial agent. When considering the use of fluoroquinolones in these difficult-to-treat infections--in which drug delivery to the site of infection may be impaired or organisms with higher minimum inhibitory concentrations may be present--an agent should be chosen whose pharmacodynamics ensure maximal drug exposure. Use of the 750-mg dose of levofloxacin should enhance therapeutic benefit in patients with nosocomial pneumonia.

OBJECTIVE

The goal of this study was to compare the efficacy and safety of levofloxacin 750 mg and imipenem/cilastatin followed by ciprofloxacin in adult patients with nosocomial pneumonia.

METHODS

This was a multicenter, prospective, randomized, open-label trial conducted in North America. Patients were randomly assigned to 1 of 2 treatment arms: levofloxacin 750 mg QD given i.v. and then orally for 7 to 15 days or imipenem/cilastatin 500 mg to 1 g i.v. every 6 to 8 hours, followed by oral ciprofloxacin 750 mg every 12 hours for 7 to 15 days. Adjunctive antibacterial therapy was mandatory in patients with documented or suspected Pseudomonas aeruginosa or methicillin-resistant Staphylococcus aureus infection. The primary predefined outcome measure was the clinical response (cure, improvement, failure, or unable to evaluate) in microbiologically evaluable patients 3 to 15 days after the end of therapy.

RESULTS

The study enrolled 438 adult patients (315 men, 123 women; mean [SD] age, 55.7 [20.04] years). Two hundred twenty patients received levofloxacin, and 218 received the comparator regimen. Demographic and baseline clinical characteristics were similar in the intent-to-treat and clinically evaluable populations. In patients evaluable for microbiologic efficacy, clinical success (cure or improvement) was achieved in 58.1% (54/93) of patients who received levofloxacin, compared with 60.6% (57/94) of patients who received the comparator regimen (95% CI, -12.0 to 17.2). Similar clinical results were seen in patients evaluable for clinical efficacy and in the intent-to-treat population. In the 187 patients evaluable for microbiologic efficacy, eradication was achieved in 66.7% (62/93) of patients receiving levofloxacin and 60.6% (57/94) of patients receiving the comparator regimen (95% CI, -20.3 to 8.3).

CONCLUSION

In this study, levofloxacin was at least as effective and was as well tolerated as imipenem/cilastatin followed by ciprofloxacin in adult patients with nosocomial pneumonia, as demonstrated by comparable clinical and microbiologic success rates.

[Efficacy and safety of cefoperazone/sulbactam in the treatment of children with mucoviscidosis during exacerbation of the bronchopulmonary process]

The use of cefoperazone/sulbactam in combination with amikacin in the treatment of 20 patients with mucoviscidosis and exacerbation of bronchopulmonary pathological process resulted in marked positive dynamics of the clinical and functional indices of the lungs state. The bacteriological effect with respect to the main pathogens in the cases of mucoviscidosis was strain-dependent: eradication of 10 (83.4%) out of 12 Staphylococcus aureus strains and only 3 (15.8%) out of 19 Pseudomonas aeruginosa strains. The most frequent adverse reaction was diarrhea (5 children) successfully corrigated by loperamide. Discontinuation of the drug use was required in 3 patients because of macrohematuria (1 child) and allergic eruption.