Staphylococcal enterotoxin B toxic shock syndrome induced by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA)

We herein report a case of toxic shock syndrome (TSS) associated with the 2009 pandemic H1N1 (pH1N1) influenza virus and a community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection in a 16-year-old Vietnamese girl. Staphylococcal enterotoxin B (SEB) was detected in the patient's serum, and the level of anti-SEB antibodies was found to be elevated. A flow cytometric analysis showed evidence of activated SEB-reactive Vβ3+ and Vβ12+ T cells. These data suggest that the CA-MRSA-induced activation of SEB-reactive T cells may cause TSS in patients with pH1N1 virus infection. Moreover, this is the first report describing immunological confirmation of SEB contributing directly to TSS in a patient fulfilling the diagnostic criteria of TSS.

Health care-associated pneumonia (HCAP): empiric antibiotics targeting methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa predict optimal outcome

Inappropriate initial antimicrobial therapy (IIAT) has been associated with decreased survival in patients with health care-associated pneumonia (HCAP). We performed a study to determine whether empiric HCAP antibiotic regimens targeting methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa are associated with greater appropriate therapy. A retrospective cohort study of culture-positive HCAP over 6 years (January 2003-December 2008) was performed at Barnes-Jewish Hospital, a 1200-bed urban teaching hospital. We identified 757 consecutive patients with HCAP. IIAT was administered to 213 (28%) patients. The pathogens most frequently associated with IIAT included P. aeruginosa (n=60, 28%), MRSA (n=58, 27%), and Acinetobacter species (n=32, 15%).Multivariate logistic regression analysis demonstrated that empiric anti-pseudomonal antibiotics (adjusted odds ratio [AOR], 1.75; 95% confidence interval [CI], 1.34-2.29; p=0.036), empiric anti-MRSA antibiotics (AOR, 1.71; 95% CI, 1.36-2.14; p=0.018), infection with Streptococcus pneumoniae (AOR, 2.82; 95% CI, 2.03-3.91; p=0.002), absence of Acinetobacter species infection (AOR, 10.57; 95% CI, 7.29-15.33; p<0.001), absence of P. aeruginosa infection (AOR, 1.69; 95% CI, 1.36-2.05; p=0.014), and absence of Stenotrophomonas maltophilia infection (AOR, 20.43; 95% CI, 9.35-44.66; p<0.001) are independent predictors of appropriate therapy for HCAP. Our study suggests that initial therapy for HCAP should include antibiotics targeting MRSA and P. aeruginosa in order to provide appropriate initial therapy. However, the selection of individual antibiotic agents should be based on local patterns of infection and adjusted when microbiology results become available.

The difference in clinical presentations between healthcare-associated and community-acquired pneumonia in university-affiliated hospital in Korea

PURPOSE

Healthcare-associated pneumonia (HCAP) has been proposed as a new category of pneumonia. However, epidemiological studies for HCAP in South Korea are limited. This study aimed to reveal the differences between HCAP and community-acquired pneumonia (CAP), especially in elderly patients, in university-affiliated hospital in South Korea.

MATERIALS AND METHODS

We conducted a retrospective observational study of patients with HCAP and CAP (older than 60 years old) who were hospitalized between January 2007 and December 2008. We compared the baseline characteristics, comorbidities, severity, pathogen distribution, antibiotics, and clinical outcomes.

RESULTS

A total of 210 patients were evaluated, including 35 patients with HCAP (17%) and 175 with CAP (83%). The most common causative organism was Streptococcus pneumoniae in CAP (33.3%), whereas, Staphylococcus aureus was most common pathogen in HCAP (40.0%). Initial inappropriate antibiotics (6.3% vs. 22.9%; p < 0.005) and initial treatment failure (15.4% vs. 31.4%; p = 0.018) were more frequent in HCAP than CAP. However, mortality (11.4% vs. 5.7%; p = 0.369) was not different between the two groups.

CONCLUSION

The present study provides additional evidence that HCAP should be distinguished from CAP, even in elderly patients, in South Korea. Physicians should consider S. aureus and MDR pathogens in selecting initial empirical antibiotics of HCAP in South Korea.

Pneumatocele in an adult

We report a case of 25-year-old male who presented with high grade fever with cough and expectoration. Chest examination revealed amphoric breath sounds on the right interscapular region. Chest X ray revealed multiple air fluid levels with collapse lung at places. Staph pneumonia with pneumatoceles is common in children but uncommon to in adult population.

[MecA and pvl genes detection in Staphylococcus aureus strains isolated from lower respiratory tract infections]

Although community-acquired Staphylococcus aureus pneumonia with highly virulent Panton-Valentine leukocidin (PVL)-positive strains, a severe disease with significant lethality, is rare, especially in adult and adolescent patients, recent reports highlight that these infections are on the rise. On the other hand, methicillin-resistant S. aureus (MRSA) is one of the high-risk and potential multi-drug resistant microorganisms.

OBJECTIVES

The aim of this study was to investigate the prevalence of mecA and pvl genes in S. aureus strains isolated from lower respiratory tract infections and to assess the antibiotic resistance profile of these strains.

MATERIAL AND METHOD

The antibiotic susceptibility testing was performed by the disk diffusion method according to CLSI recommendations in 32 consecutive non-repeated S. aureus strains isolated from sputum specimens and endotracheal aspirates of hospitalized patients over the period from January 2005 to December 2009. Only 20 strains (2008-2009) were tested for the presence of mecA and pvl genes by real-time PCR and detection with specific fluorescence probes.

RESULTS

Of the 32 S. aureus isolates, 68.7% were MRSA. MRSA strains showed higher resistance rates to gentamicin, tetracycline, rifampicin, fluoroquinolones comparing to the methicillin susceptible ones. Only one strain produced pvl; it was isolated from a 7 year old child with lethal sepsis with pulmonary and meningeal secondary localisations.

CONCLUSIONS

Glicopeptides and linezolid are therapeutic options indicated in the treatment of staphylococcal pneumonia produced either by MRSA strains or pvl positive S. aureus strains.

[Comparison of teicoplanin and linezolid therapies in patients with methicillin-resistant Staphylococcus aureus pneumonia acquired from respiratory intensive care unit]

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the high-risk and potential multi-drug resistant microorganisms that leads to infection in intensive care unit (ICU). Although standard antibiotics used for its treatment are glycopeptides, linezolid is considered as an alternative treatment especially in hospital-acquired pneumonia (HAP). The aim of this retrospective study was to compare the results of linezolid and teicoplanin treatments in patients with MRSA isolated from their respiratory samples in ICU. In our respiratory ICU, 41 consecutive patients (28 males, mean age 66.0 ± 16.0 years) diagnosed as HAP due to MRSA were included in the study. Teicoplanin was used in 22 patients and linezolid treatment was given to 19 patients. In the linezolid group, mean age and Acute Physiology Assessment and Chronic Health Evaluation (APACHE) II score were found higher (68.9 ± 12.5 vs. 63.5 ± 18.5 and 25.7 ± 6.4 vs. 23.2 ± 4.9, respectively), and PaO2/FiO2 ratio was lower (176.4 ± 58.2 vs. 191.6 ± 91.3) however, the differences between the two groups were not statistically significant. There was no difference between the two groups in terms of hospitalization indications, co-morbid diseases, other baseline findings and risk factors for development of HAP caused by MRSA. Invasive mechanical ventilation was applied to 86.4% of the patients in teicoplanin group and 84.2% in linezolid group (p> 0.05). The rates of bacteremia were found as 22.7% and 31.6% in teicoplanin and linezolid groups, respectively (p>0.05). Bacteriological eradication was achieved in all patients given linezolid, whereas this rate was 72.7% in patients on teicoplanin therapy (p= 0.048). There was no difference with regards to durations of ICU and hospital stay between the two groups. The mortality rate was found lower in the linezolid group than the teicoplanin group (42.1% vs. 63.6%), however this difference was not found statistically important (p> 0.05). In conclusion; the present study demonstrated that better microbiological eradication was achieved by linezolid therapy in pneumonia caused by MRSA in ICU, however, the clinical efficacy and survival rates were similar to teicoplanin therapy.

[Necrotizing pneumonia by community-acquired, methicillin-resistant Staphylococcus aureus in Colombia]

The emergence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) as a cause of severe infections has been described in the recent years. In 2006, the first report of skin and soft tissue infection by CA-MRSA was published in Colombia. Herein, two additional cases of CA-MRSA are reported with a clinical course characterized by rapid progression, prolonged stay in the intensive care unit and complication of pneumonia with the onset of empyema. Both adult patients developed acute renal failure, and were treated with linezolide; the subsequent clinical response showed adequate treatment response. Molecular characterization of the isolates indicated the presence of the mecA gene carrying the cassette SCCmec type IV and the production of the toxin panton-valentine leukocidin.

Comparison of community-acquired pneumonia due to methicillin-resistant and methicillin-susceptible Staphylococcus aureus producing the Panton-Valentine leukocidin

OBJECTIVE

To investigate the clinical features and prognosis of patients with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) community-acquired pneumonia (CAP) producing the Panton-Valentine leukocidin (PVL).

METHODS

PubMed and Scopus were searched. Inclusion was stratified according to S. aureus susceptibility and clinical, microbiological and outcome data of patients with S. aureus CAP; both primary and secondary cases of CAP (hematogenous spread from other sites of infection) were included.

RESULTS

We identified 71 articles reporting data on patients with MRSA (n = 76) and MSSA (n = 31) PVL-positive CAP. There were no differences in demographics and history among patients with MRSA and MSSA CAP. Features associated with MRSA CAP were gastrointestinal tract symptoms (P = 0.016) and unilobar infiltrates (P = 0.043). Features associated with MSSA CAP were airway hemorrhage (P = 0.01), multilobar infiltrates (P = 0.043) and acute respiratory distress syndrome (ARDS, P = 0.023). Although MSSA patients were more likely to receive initial appropriate antimicrobial therapy (P < 0.001), there was no difference in mortality between the two groups (P = 0.919). Univariate analysis showed that influenza-like symptoms (P < 0.001), multi-organ failure (P < 0.001), admission to the intensive care unit (P < 0.001), mechanical ventilation (P < 0.001), leucopenia (P < 0.001), shock (P = 0.001), development of complications (P = 0.003), vein thrombosis (P < 0.001), disseminated intravascular coagulation (P = 0.03), acidosis (P = 0.012), rash (P = 0.024), ARDS (P = 0.021), necrotizing pneumonia (P = 0.026), and use of macrolides after culture results (P = 0.011) were factors associated with death.

CONCLUSIONS

Patients with MRSA PVL-positive CAP did not have higher rates of mortality than patients with MSSA PVL-positive CAP.

Identifying exposure targets for treatment of staphylococcal pneumonia with ceftobiprole

Ceftobiprole is a cephalosporin with potent activity against methicillin (meticillin)-resistant Staphylococcus aureus (MRSA). In order to treat patients with severe staphylococcal pneumonia, it is important to understand the drug exposure required to mediate the killing of multiple log(10) cells in a preclinical-infection model. We measured drug exposure in terms of the percentage of penetration of the drug into epithelial lining fluid (ELF) and in terms of the time for which the drug concentration was above the MIC (time>MIC) in plasma and ELF. In a murine model of staphylococcal pneumonia, we demonstrated that ceftobiprole penetrated into ELF from the plasma at a median level of nearly 69% (25th to 75th percentile range, 25 to 187%), as indexed to the ratio of values for the area under the concentration-time curve in ELF and plasma. The total-drug times>MIC in ELF that were required to kill 1 log(10) and 2 log(10) CFU/g of lung tissue were 15% and 25% of the dosing interval. We also examined the penetration of ELF by ceftobiprole in volunteers, demonstrating mean and median penetration percentages of 25.5% and 15.3%, respectively (25th to 75th percentile range, 8 to 30%). Attainment rates were calculated for kill targets of 1 log(10) and 2 log(10) CFU/g, taken from the murine model, but using the volunteer ceftobiprole ELF penetration data. The standard dose for ceftobiprole is 0.5 g every 8 h as a 2-h infusion. The attainment rates remained above 90% for 1-log(10) and 2-log(10) CFU/g kill targets at MICs of 1 and 0.5 mg/liter, respectively. Taking the expectation over the distribution of ceftobiprole MICs for 4,958 MRSA isolates showed an overall target attainment of 85.6% for a 1-log(10) CFU/g kill and 79.7% for a 2-log(10) CFU/g kill. It is important to derive exposure targets in preclinical-infection models of the infection site so that these targets can be explored in clinical trials in order to optimize the probability of a good clinical outcome.

The management of acute lower respiratory tract infection

Acute lower respiratory tract infection is associated with an increase of the morbidity, mortality and assistance cost. This review focus on the diagnosis and treatment of acute lower respiratory tract infection. There is not a gold standard in the microbiological diagnostic tests for the diagnosis of acute lower respiratory tract infection; thus, the choice of strategy used to diagnose will be dependent on consideration of local expertise and availability of personnel to perform the procedure. I suggest obtain a lower respiratory tract secretion sample by endotracheal aspirate for quantitative culture at the time of suspicion of acute lower respiratory tract infection; and by protected specimen brush and/or bronchoalveolar lavage in patients with a bad response to the initial antimicrobials used. In relation to the treatment of acute lower respiratory tract infection, I suggest the following approach: early onset of antimicrobial agents, choice of antimicrobial agents according the local bacteriologic patterns, combination therapy for the empiric treatment, de-escalation and monotherapy for the definitive treatment in responsive patients and with microorganism responsible documented, continuous infusion for betalactam antibiotics and vancomycin, single dayle dosage for aminoglycosides, administration of antimicrobials topically (inhaled or instilllated) in unresponsive patients, antibiotic heterogeneity, short-course of 7-10 days of antimicrobial therapy in patients with a good clinical response.

[Community-acquired Staphylococcus aureus pneumonia following influenza and the choice of empirical antibiotic treatment]

A 30-year-old man presented with community-acquired pneumonia (CAP), directly following influenza. Sputum Gram stain confirmed Staphylococcus aureus pneumonia. Initial empirical antimicrobial therapy did not cover S. aureus. The isolated S. aureus strain contained genes encoding exotoxins, such as Panton-Valentine leukocidin (PVL). This exotoxin is associated with high mortality and methicillin resistance, but in this patient the strain was susceptible to methicillin. The patient died. In the Netherlands the risk of methicillin resistance in PVL-positive S. aureus CAP is low but real. This should be taken into account when selecting empirical treatment, which can include the combination of flucloxacillin and rifampicin. This case report illustrates the difficulty in predicting the causative agent in CAP and highlights the usefulness of the sputum Gram stain. Moreover, clinical awareness and recognition of S. aureus CAP remains essential to the early initiation of directed therapy.

A retrospective analysis of possible renal toxicity associated with vancomycin in patients with health care-associated methicillin-resistant Staphylococcus aureus pneumonia

OBJECTIVE

The goal of this investigation was to determine whether more aggressive vancomycin dosing is associated with greater risk for renal toxicity in patients with health care-associated pneumonia (HCAP) attributed to methicillin-resistant Staphylococcus aureus (MRSA).

METHODS

This was a retrospective, single-center, observational cohort study. The following information was obtained for all study patients from automated hospital, microbiology, and pharmacy databases: age, sex, weight, serial serum creatinine (SCr), age- and sex-adjusted creatinine clearance (CrCl) during receipt of vancomycin, vancomycin serum trough concentrations, duration of vancomycin therapy, and Acute Physiology and Chronic Health Evaluation II scores. Renal toxicity was defined as either a 0.5-mg/dL increase from baseline in SCr or a >or=50% increase in SCr based on serial SCr measurements. Data for patients who met the definition of renal toxicity were compared with data for those who did not.

RESULTS

Ninety-four patients (mean [SD]age, 59.0 [15.6] years; 59 [62.8%] men; 73 (77.7%) white; mean baseline CrCl, 70.3 [23.0] mL/min) were identified as having MRSA HCAP. Forty (42.6%) patients developed renal toxicity. Patients who developed renal toxicity were significantly more likely than patients who did not develop renal toxicity to have greater mean vancomycin serum trough concentrations (20.8 [9.9] g/mL vs 14.3 [6.7] g/mL, respectively; P < 0.001), vancomycin serum trough concentrations >or=15 g/mL (67.5% vs 40.7%; P = 0.01), and a prolonged duration (>or=14 days) of vancomycin treatment (45.0% vs 20.4%; P = 0.011). Logistic regression analysis identified a maximum vancomycin serum trough concentration of >or=15 g/mL as being independently associated with renal toxicity (adjusted odds ratio = 2.82; 95% CI, 1.02-7.74; P = 0.045). The overall mean change in CrCl for the study population was -13.5 (-16.0) mL/min (range, 0.0 to -62.6 mL/min). Patients with maximum measured vancomycin serum trough concentrations >or=15 g/mL (n = 49) had significantly greater absolute changes in CrCl compared with patients with maximum measured vancomycin serum trough concentrations <15 g/mL (n = 45) (-18.9 [-17.0] vs -7.6 [-12.5] mL/min, respectively; P < 0.001).

CONCLUSIONS

The results suggest that aggressive vancomycin dosing and prolonged vancomycin administration may be associated with greater risk for renal toxicity in patients with MRSA HCAP. However, this retrospective study cannot establish causation, and a prospective, randomized, double-blind trial is needed.

Methicillin-resistant Staphylococcus aureus pneumonia after thoracic surgery: successful treatment with linezolid after failed vancomycin therapy

We describe 3 patients with methicillin-resistant Staphylococcus aureus, hospital-acquired pneumonia who demonstrated a microbiological and clinical failure with vancomycin despite adequate trough levels. All 3 patients were cured with linezolid.

Treatment of hospital-acquired pneumonia caused by methicillin-resistant Staphylococcus aureus

Nosocomial pneumonia and ventilator-assisted pneumonia may be polymicrobial and can be caused by a wide spectrum of pathogens. Potentially multidrug-resistant microorganisms often represent the 'core' pathogens of the most severe infections. Among Gram-positive pathogens, methicillin-resistant Staphylococcus aureus (MRSA) plays a key role, mainly in mechanically ventilated patients or in patients with specific risk factors. The mainstay of treatment for MRSA pneumonia has been glycopeptide antibiotics, i.e. vancomycin and, to a lesser extent, teicoplanin. However, owing to its insufficient penetration into lung compartments, vancomycin may result in therapeutic failure or slow clinical responses. Moreover, vancomycin serum levels must be monitored in order to minimise nephrotoxicity and to maximise the concentration in the lung. Finally, the emergence of staphylococci isolates with reduced susceptibility to vancomycin suggests that glycopeptides should no longer be considered as first-line antibacterial agents for Gram-positive lung infections. Among new therapeutic options, linezolid may be an appropriate choice for MRSA pulmonary infections owing to its good pharmacokinetic profile in the lung and its acceptable tolerability, especially in patients with renal insufficiency or in those receiving other nephrotoxic agents. However, to contain the increasing emergence of drug resistance among hospitalised patients, these novel antimicrobial agents should be used judiciously, restricting their use to patients not responsive to, or intolerant of, glycopeptides. Other new drugs under development appear to be promising and deserve further evaluation.

Successful thoracoscopic treatment of severe bilateral empyema in an infant

We report a case of rapid progression of bilateral pyothorax exacerbated by viral influenza in an infant. The patient, an 11-month-old girl, was diagnosed with viral influenza, and oseltamivir phosphate was administered. However, after only 4 days the influenza was followed by rapid progression of methicillin-susceptible Staphylococcus aureus (MSSA) pneumonia and pyothorax, resulting in disseminated intravascular coagulation. Because thoracentesis and antibiotics could not control the pyothorax, a serious condition, we performed bilateral video-assisted thoracoscopic decortication on the eighth hospital day. She recovered with excellent lung expansion and was discharged on the 37th hospital day.

Community MRSA

Additional to epidemic methicillin resistant Staphylococcus aureus (haMRSA) which had been disseminated in and between hospitals, MRSA emerged in the community independent upon the nosocomial setting (caMRSA). caMRSA possess the capacity to form Panton-Valentine-Leukocidin (PVL) as a special virulence factor. In general PVL-positive S. aureus isolates are associated with necrotizing skin and soft tissue infections as well as with necrotizing pneumonia. caMRSA are less "broad" resistant against different groups of antibiotics as haMRSA and require special attention when performing antimicrobial susceptibility testing. Prevention of further dissemination of caMRSA requires appropriate diagnosis, therapy and sanitation of the carrier state. Hygienic measures have not only to be taken in ambulant treatment but also in households of affected patients.

Methicillin-Resistant Staphylococcus aureus Necrotizing Pneumonia Arising From an Infected Episiotomy Site

BACKGROUND

We report a case of methicillin-resistant Staphylococcus aureus (MRSA) sepsis and pneumonia in a postpartum patient.

CASE

A 21-year-old gravida 1 para 1 presented on postpartum day 9 with persistent elevated fever, dyspnea, cellulitis of the upper extremities, and an infected episiotomy site. Computed tomography of the chest revealed multiple widely distributed nodules and bilateral infiltrates with central cavitations. Sputum, blood, urine, and episiotomy site cultures grew MRSA, subsequently demonstrated by molecular fingerprinting and antibiotic susceptibility to be community acquired. A magnetic resonance imaging of the pelvis demonstrated pelvic thrombophlebitis.

CONCLUSION

Community-acquired MRSA is an emerging problem, which may present as skin and soft tissue infections or sepsis. Seeding from an infected episiotomy site seems to be a potential route of systemic infection. The use of empirical treatment with beta-lactam agents may fail. Appropriate cultures should be obtained and if MRSA is diagnosed, vancomycin should be employed.

[Use of linezolid for the treatment of lung infections in adults with cystic fibrosis]

INTRODUCTION

Linezolid, a new antistaphylococcal agent for oral or intravenous administration is active against Staphylococcus aureus with limited sensitivity to glycopeptides. The purpose of the present work was to compare data in the literature with practical clinical experience with the use of linezolid for lung infections in adult cystic fibrosis patients with the objective of developing local guidelines for use.

MATERIAL AND METHODS

This retrospective clinical study was conducted in the adult pneumology department of a university hospital.

RESULTS

The main clinical signs leading to prescription of linezolid were aggravating cough, bronchial obstruction, and exercise-induced fatigue. Among 42 cystic fibrosis patients, six aged 24+/-3 years were given 22 treatments of linezolid. Two patients were given the drug once and the others 2, 4, 5, and 9 times, 600 mg b.i.d. Mean duration of treatment with linezolid was 16+/-5 days. Among the six patients, two presented meti-R S. aureus infection. For twelve cases, clinical improvement was observed; and in two others the situation worsened leading to interruption of linezolid.

CONCLUSIONS

There are few reports in the literature on use of linezolid in cystic fibrosis patients. Writing internal guidelines for our department has enabled standardized use: 600 mg b.i.d. p.o. for 14 days as second-line treatment for bronchial exacerbation of S. aureus infection.

A holistic approach to MRSA eradication in critically ill patients with MRSA pneumonia

BACKGROUND

The number of Methicillin-resistant Staphylococcus aureus (MRSA) pneumonia cases is increasing in many European countries. In this observational study in one medical and three surgical ICUs multiple interventions for the treatment and eradication of nosocomial MRSA-pneumonia were used.

PATIENTS AND METHODS

Twenty-one critically ill patients (age: 59 +/- 14 years, 15 males/6 females, 18 ventilator-associated, 3 nosocomial, clinical pulmonary infection score > 6 in all patients, APACHE II 18 +/- 5) were enrolled. The patients were treated with a 7-day course of iv linezolid (600 mg bid) plus rifampicin (600 mg bid), endotracheal vancomycin 100 mg qid, thrice daily mouth and throat washing with chlorhexidine 1% fluid and nasal mupirocin ointment, twice daily skin and hair washings with chlorhexidine gluconate 4% and tracheostomy (n = 8) wound care with povidone-iodine spray. Control samples (endotracheal secretions, nose, wound, and pharyngeal swabs) were taken 2, 3, 4, 7 days and 2 months thereafter. Multilobular pneumonia was seen in 16, pleural effusion in 12, and MRSA bacteremia in 4 patients.

RESULTS

One patient died during the follow-up period due to cerebral bleeding. In the remaining 20 patients, pneumonia was clinically cured in all patients and all patients were free of MRSA after eradication. Six patients died due to myocardial infarction (n = 3), gram-negative septic shock (n = 2), herpes encephalitis (n = 1) > 7 days after eradication. No MRSA reinfection occurred during the control period.

CONCLUSION

We conclude that in patients with MRSA pneumonia an approach using a 7-day course of intravenous linezolid plus rifampicin, intratracheal vancomycin, nasal mupirocin, cutaneous and oropharyngeal chlorhexidin plus povidone-iodine cures pneumonia and is effective for MRSA eradication.

Predictors of mortality for methicillin-resistant Staphylococcus aureus health-care-associated pneumonia: specific evaluation of vancomycin pharmacokinetic indices

OBJECTIVE

The goal of this investigation was to determine whether vancomycin pharmacokinetic indexes (eg, serum trough concentrations or area under the concentration curve [AUC] values) were associated with mortality for patients with health-care-associated pneumonia (HCAP) attributed to methicillin-resistant Staphylococcus aureus (MRSA).

DESIGN

A retrospective, single-center, observational cohort study.

SETTING

Barnes-Jewish Hospital, a 1,200-bed urban teaching facility.

PATIENTS

Adult patients requiring hospitalization who were identified as having HCAP attributed to MRSA by BAL semi-quantitative cultures.

INTERVENTIONS

Retrospective data collection from automated hospital, microbiology, and pharmacy databases.

MEASUREMENTS AND MAIN RESULTS

One hundred two patients with MRSA HCAP were identified over a 6.5-year period. Thirty-two patients (31.4%) died during their hospitalization. The mean (+/- SD) vancomycin trough concentrations (13.6 +/- 5.9 vs 13.9 +/- 6.7 microg/mL, respectively; p = 0.866) and AUC values (351 +/- 143 vs 354 +/- 109 microg/h/mL, respectively; p = 0.941) did not differ between survivors and nonsurvivors. The stratification of the vancomycin trough concentrations and AUC values yielded no relationship with hospital mortality.

CONCLUSIONS

We found no evidence that greater vancomycin trough concentrations or AUC values correlated with hospital outcome. Based on these results, aggressive dosing strategies for vancomycin (eg, trough concentrations of > 15 microg/mL) may not offer any advantage over traditional dose targets (range, 5 to 15 microg/mL).

Successful salvage therapy with tigecycline after linezolid failure in a liver transplant recipient with MRSA pneumonia

Pulmonary infections are a significant cause of morbidity and mortality after liver transplantation. Infections with methicillin-resistant Staphylococcus aureus (MRSA) have increased in the last 10 years. Mortality may exceed 80% in liver transplant recipients who develop MRSA pneumonia. A 57-year-old male following living-donor liver transplantation developed a right-sided MRSA pneumonia 6 weeks after transplantation, which required artificial ventilation for 14 weeks. Initially, pneumonia was treated with linezolid. However, after 12 days under current therapy, the infection spread out to both lungs. At that time. we initiated the treatment with tigecycline. Under this therapy, the patient could be cured from MRSA pneumonia and was extubated. We detected no tigecycline related hepatotoxic effect. In conclusion, this case suggests that tigecycline may be useful in the salvage therapy of pneumonia due to MRSA after linezolid failure.

[Severe community acquired pneumonia due to Staphylococcus aureus in children. About two cases]

The staphylococcal pneumonia is the prerogative of the infant but rare cases were observed in the childhood. We report the observation of two children aged respectively of six years and three years and a half having presented a particular form of severe staphylococcal pneumonia apart from any context of immunodepression. The identification of the particular strains producing toxins Like the Panton and Valentine leukocidin constitutes the first stage of the comprehension of this atypical form of pneumonia. Through these observations and with a review of literature we underline the specific clinical and biological aspects of this form.

Potency of DX-619, a novel des-F(6)-quinolone, in haematogenous murine bronchopneumonia caused by methicillin-resistant and vancomycin-intermediate Staphylococcus aureus

In this study, the potency of DX-619, a novel des-fluoro(6)-quinolone agent, was compared with that of vancomycin (VCM) in a murine model of haematogenous bronchopneumonia infection caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-intermediate S. aureus (VISA). The minimum inhibitory concentrations (MICs) of DX-619 and VCM against MRSA were 0.03 microg/mL and 1.0 microg/mL, respectively, whilst the MICs against VISA were 0.125 microg/mL and 8.0 microg/mL, respectively. Treatment with DX-619 resulted in a significant decrease in the number of viable bacteria in the MRSA infection model (mean+/-standard error of the mean for control, VCM and DX-619 groups: 7.97+/-0.32, 7.19+/-0.33 and 2.91+/-0.60 log(10) colony-forming units/lung, respectively). For infection with VISA, mice were pre-treated with cyclophosphamide. The survival rate of mice treated with DX-619 (90% survival) was significantly higher than survival rates in the other two groups (45% both for VCM and control groups; P<0.05). Histopathological examination revealed that inflammatory changes in the DX-619-treated group were less marked than in the other two groups. The parameters in lung tissue for the area under the concentration-time curve/MIC ratio both for MRSA and VISA were higher in the DX-619 group than in the VCM group. Our results emphasise the potency of DX-619 against MRSA and VISA murine haematogenous pulmonary infection.

Cost-effectiveness analysis of linezolid compared with vancomycin for the treatment of nosocomial pneumonia caused by methicillin-resistant Staphylococcus aureus

OBJECTIVE

This study compared the cost-effectiveness of linezolid and vancomycin in the treatment of patients with nosocomial pneumonia (NP) caused by methicillin-resistant Staphylococcus aureus (MRSA).

METHODS

A retrospective decision-analytic model was applied to pooled data from 2 prospective, randomized, controlled, double-blind studies, and claims data from a large health plan (3.3 million members) located in the Mid-Atlantic region. Using hospital claims for patients in the health plan with suspected NP, we then determined their daily billed (submitted) hospital charges for 4 mutually exclusive potential health outcomes of linezolid or vancomycin treatment: survival with bacteremia, survival without bacteremia, nonsurvival with bacteremia, and nonsurvival without bacteremia. To generate the expected total daily billed hospital charge for each drug-treatment group, we weighted the determined daily billed hospital charges by the probabilities of each outcome developing in each treatment arm, as derived from the clinical-trial data. Drug acquisition costs were then incorporated, and the difference in expected total costs relative to the difference in rates of survival between the linezolid and vancomycin arms was used to calculate the incremental cost-effectiveness ratio (ICER) for linezolid.

RESULTS

Costs were higher for nonsurviving patients compared with surviving patients. Estimated median daily billed treatment charges were $2888 for linezolid and $2993 for vancomycin. Based on Monte Carlo simulations, the respective 95% CIs were $2671 to $3106 and $2615 to $3372. Using mean treatment durations of 11.3 and 10.7 days, respectively, we obtained expected total hospitalization charges of $32,636 for linezolid treatment (95% CI, $30,182-$35,098), compared with $32,024 for vancomycin treatment (95% CI, $27,978-$36,078). The ICER for linezolid per life saved was $3600.

CONCLUSIONS

The higher acquisition cost of linezolid was almost completely offset by improved survival and a reduction in health care costs associated with improved survival. As a result, linezolid was almost cost-neutral compared with vancomycin in the treatment of NP caused by MRSA.

Hospital-acquired pneumonia in the 21st century: a review of existing treatment options and their impact on patient care

Hospital-acquired pneumonia is a common nosocomial infection, with significant morbidity and mortality, and represents a major therapeutic challenge to clinicians. The therapeutic approach must be patient-oriented and institution-specific. The specific risk factors of each patient, such as previous antibiotic exposure, underlying diseases, length of hospital stay and the local patterns of antimicrobial resistance, should guide physicians in their decision of the initial optimal empirical therapy. Delays in the initiation or inappropriate/inadequate initial therapy are related to increased mortality and worse outcomes. In responding patients, as soon as culture data are available, efforts should be made to change the initial broad spectrum antibiotic regimen to a more targeted one (de-escalation). The optimal duration of treatment is a matter of debate, but courses longer than 1 week are rarely justified.

Morbidity and cost burden of methicillin-resistant Staphylococcus aureus in early onset ventilator-associated pneumonia

Introduction

To gain a better understanding of the clinical and economic outcomes associated with methicillin-resistant Staphylococcus aureus (MRSA) infection in patients with early onset ventilator-associated pneumonia (VAP), we retrospectively analyzed a multihospital US database to identify patients with VAP over a 24 month period (2002–2003).

Method

Data recorded included physiologic, laboratory, culture, and other clinical variables from 59 institutions. VAP was defined as new positive respiratory culture after at least 24 hours of mechanical ventilation (MV) and the presence of primary or secondary ICD-9-CM diagnosis codes of pneumonia. Outcomes measures included in-hospital morbidity and mortality for the population overall and after onset of VAP (duration of MV, intensive care unit [ICU] stay, in-hospital stay, and case mix and severity-adjusted operating cost). The overall cost was calculated at the hospital level using the Center for Medicare and Medicaid Services Cost/Charge Index for each calendar year.

Results

A total of 499 patients were identified as having VAP. S. aureus was the leading organism (31% of isolates). Patients with MRSA were significantly older than patients with methicillin-sensitive Staphylococcus aureus (MSSA; median age 74 versus 67 years, P < 0.05) and more likely to be medical patients. Compared with MSSA patients, MRSA patients on average consumed excess resources of 4.4 (95% confidence interval 0.6–8.2) overall MV days, 3.8 (-0.5 to +8.0) days of inpatient length of stay (LOS), 5.3 (1.0–9.7) ICU days, and US$7731 (-US$8393 to +US$23,856) total cost after controlling for case mix and other factors. Furthermore, MRSA patients needed excess resources after the onset of VAP (4.5 [95% confidence interval 1.0–8.1] MV days, 3.7 [-0.5 to +8.0] inpatient days, and 4.4 [0.4–8.4] ICU days) after controlling for the same case mix and admission severity covariates.

Conclusion

S. aureus remains a common cause of VAP. VAP due to MRSA was associated with increased overall LOS, ICU LOS, and attributable ICU LOS compared with MSSA-related VAP. Although not statistically significant because of small sample size and large variation, the attributable excess costs of MRSA amounted to approximately US$8000 per case after controlling for case mix and severity.

Fatal bacteraemic pneumonia due to community-acquired methicillin-resistant Staphylococcus aureus

The recent worldwide surge in the incidence of fatal pneumonia caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has generated renewed interest in this well-known organism. We describe two cases of fulminant bacteraemic pneumonia due to CA-MRSA at the National University Hospital in Singapore and provide further epidemiological descriptors of this potentially-deadly disease. The first patient was an 83-year-old woman while the second was a 71-year-old man, none of whom had risk factors for hospital-acquired MRSA colonisation. Clinicians should be aware of the possibility of severe community-acquired pneumonia caused by this organism. Adequate empirical antimicrobial coverage for this important pathogen should be considered.

The role of vancomycin in the treatment paradigm

Vancomycin was introduced in the United States in 1956 as a possible treatment for infections due to penicillin-resistant Staphylococcus aureus, but it was not used widely because of toxicity and the nearly simultaneous development of semisynthetic antibiotics and cephalosporins. Thus, its main indication was the treatment of serious gram-positive infections in penicillin-allergic patients. For susceptible strains of S. aureus, vancomycin was more rapidly bactericidal than penicillin, nafcillin, or cefazolin, and, in a rabbit model of S. aureus endocarditis, sterilization of vegetations was more rapid with vancomycin. In clinical practice, however, nafcillin remained the treatment of choice for staphylococcal bacteremia, largely because it had failure rates of only 4%. With the appearance of methicillin-resistant S. aureus and coagulase-negative staphylococci, vancomycin became the drug of choice for these infections. Recently, the efficacy of vancomycin has been questioned because of vancomycin's increasing minimum inhibitory concentrations among staphylococci, poor tissue penetration, and apparently slower bacterial killing than previously was recognized.

Multi-systemic methicillin resistant Staphylococcus aureus (MRSA) community-acquired infection

BACKGROUND

An alarming increase of the incidence of community-acquired infections due to methicillin resistant Staphylococcus aureus (MRSA) has been noted in several countries during the recent years.

CASE REPORT

We present the case of a 64-year-old male who complained of fever, shortness of breath, productive cough, and mild low back pain. The patient was diagnosed to have severe community-acquired pneumonia caused by methicillin resistant Staphylococcus aureus. Due to the severity of his respiratory symptoms and the history of back injury, the mild low back pain did not receive the appropriate attention. It became clear later that the back pain was caused by an extra-pulmonary focus of the MRSA infection.

CONCLUSIONS

Staphylococcus aureus has been reported to be the cause of considerably different proportions of patients with community-acquired pneumonia in studies from various parts of the world. Our case emphasizes the occasionally multi-systemic manifestations of community-acquired MRSA infections and the difficulties in their control.