Treatment of methicillin-resistant Staphylococcus aureus ventilator-associated pneumonia with high-dose vancomycin or linezolid

Treatment of Achromobacter Ventilator-Associated Pneumonia in Critically Ill Trauma Patients

BACKGROUND

Achromobacter sp are nonfermenting Gram-negative bacilli (NFGNB) that rarely cause severe infections, including ventilator-associated pneumonia (VAP). Data on the treatment of Achromobacter pneumonia are very limited, and the organism has been associated with a high mortality rate. Thus, more data are needed on treating this organism.

OBJECTIVE

To evaluate the treatment of Achromobacter VAP in critically ill trauma patients.

METHODS

This retrospective, observational study evaluated critically ill trauma patients who developed Achromobacter VAP. A previously published pathway for the diagnosis and management of VAP was used according to routine patient care. This included the use of quantitative bronchoscopic bronchoalveolar lavage cultures to definitively diagnose VAP.

RESULTS

A total of 37 episodes of Achromobacter VAP occurred in 34 trauma intensive care unit patients over a 15-year period. The most commonly used definitive antibiotics were imipenem/cilastatin, cefepime, or trimethoprim/sulfamethoxazole. The primary outcome of clinical success was achieved in 32 of 37 episodes (87%). This is similar to previous studies of other NFGNB VAP (eg, Pseudomonas, Acinetobacter) from the study center. Microbiological success was seen in 21 of 28 episodes (75%), and VAP-related mortality was 9% (3 of 34 patients).

CONCLUSIONS

Achromobacter is a rare but potentially serious cause of VAP in critically ill patients. In this study, there was an acceptable success rate compared with other causes of NFGNB VAP in this patient population.

Reducing acute kidney injury due to vancomycin in trauma patients

BACKGROUND

Supratherapeutic vancomycin trough levels are common after trauma and associated with both increased acute kidney injury (AKI) and mortality. We sought to limit the adverse effects of vancomycin in trauma patients through more frequent trough monitoring.

METHODS

Beginning in January 2011, trauma patients treated with vancomycin had trough levels (VT) monitored daily until steady state was reached. Trauma patients admitted from January 2011 to May 2015 (POST) were compared with those admitted from January 2006 to December 2010 (PRE). Inclusion criteria required administration of intravenous vancomycin, admission serum creatinine (SCr), and SCr within 72 hours of highest VT. Acute kidney injury was defined as an increase in SCr of at least 0.3 mg/dL or 50% from admission to post-vancomycin administration. Those in the POST group were prospectively followed up until discharge or death.

RESULTS

Two hundred sixty-three patients met inclusion criteria in the PRE-phase and 115 in the POST-phase. The two groups were similar in age, gender, race, body mass index, pre-existing comorbidities, admission systolic blood pressure, Glasgow Coma Scale, and head Abbreviated Injury Scale. Injury Severity Score was higher in the POST cohort (18 PRE vs. 25 POST, p < 0.001). Compared with PRE, the POST cohort had lower rates of supratherapeutic VT (>20 mg/L) (34.6% PRE vs. 22.6% POST, p = 0.02) and AKI (30.4% PRE vs. 19.1% POST, p = 0.026). After adjusting for confounders, the POST group had a significantly lower risk of AKI with an adjusted odds ratio of 0.457 (p = 0.027). There was a trend toward decreased mortality in the POST cohort, but this did not reach significance (10% PRE vs. 5.2% POST, p = 0.162).

CONCLUSIONS

A reduction in AKI was observed in trauma patients with daily vancomycin trough levels monitored until steady state. Increased awareness regarding closer surveillance of VT in trauma patients may limit the incidence of vancomycin-related nephrotoxicity.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Healthcare-associated pneumonia with positive respiratory methicillin-resistant Staphylococcus aureus culture: Predictors of the true pathogenicity

AIM

Although methicillin-resistant Staphylococcus aureus (MRSA) is commonly isolated from respiratory specimens in healthcare-associated pneumonia (HCAP), it is difficult to determine the causative pathogen because of the possibilities of contamination/colonization. The present study aimed to identify clinical predictors of the true pathogenicity of MRSA in HCAP.

METHODS

Patients with HCAP with positive MRSA cultures in the sputum or endotracheal aspirates who were admitted to Seirei Mikatahara General Hospital, Hamamatsu, Japan, from 2009 to 2014 were enrolled. According to the administered drugs and the treatment outcomes, patients with true MRSA pneumonia (MP) and those with contamination/colonization of MRSA (false MP) were identified. Baseline characteristics were compared between groups, and clinical predictors of true MP were evaluated by logistic regression analyses.

RESULTS

A total of 93 patients (mean age 78.7 ± 12.6 years) were identified and classified into the true MP (n = 16) or false MP (n = 77) groups. Although baseline characteristics were broadly similar between groups, the true MP group had significantly more patients with PaO₂  ≤ 60 Torr/pulse oximetry saturation ≤90% and those with MRSA single cultivation. Both variables were significant predictors of true MP in multivariate analysis (odds ratio of PaO₂  ≤ 60 Torr/pulse oximetry saturation ≤90%: 5.64, 95% confidence interval 1.17-27.32; odds ratio of MRSA single cultivation: 4.76, 95% confidence interval 1.22-18.60).

CONCLUSIONS

Poor oxygenation and MRSA single cultivation imply the true pathogenicity of MRSA in HCAP with positive respiratory MRSA cultures. The present results might be helpful for the proper use of anti-MRSA drugs in this population. Geriatr Gerontol Int 2017; 17: 456-462.

Continuous infusion vs intermittent vancomycin in neurosurgical intensive care unit patients

PURPOSE

Target plasma level achievement has remained a challenge in neurosurgical intensive care unit patients receiving intravenous vancomycin. We evaluated continuous infusion (CI) and intermittent vancomycin dosing strategies in these patients.

METHODS

This retrospective cohort compared CI vancomycin (target random levels, 20-30 mg/L) to intermittent vancomycin (target troughs, 15-20 mg/L) in regards to achievement of target plasma levels, nephrotoxicity, pharmacodynamic target attainment, and cost savings in 130 patients.

RESULTS

Continuous infusion resulted in greater achievement of goal plasma concentrations at the first steady-state level (40 vs 21.5%, P = .02), more rapid achievement of goal plasma concentrations (2.04 vs 3.76 days, P < .0001), and increased time within therapeutic range (55% vs 34%, P < .0001) but no significant difference in nephrotoxicity (15.4% vs 21.5%, P = .5). Continuous infusion improved pharmacodynamic target attainment (92.3% vs 30.8%, P < .0001) and also reduced levels drawn (3.8 vs 5.7, P = .0007), dose adjustments (1.4 vs 2.4, P = .0006), days of therapy (10.4 vs 14.1, P = .01), and mean total daily dose requirements (33 vs 35.7 mg/kg, P < .0001) per patient.

CONCLUSIONS

Continuous infusion appears beneficial for improving attainment of target plasma concentrations, pharmacodynamic goals, and financial burden, without increasing risk of acute kidney injury.

Importance of Decision Support Implementation in Emergency Department Vancomycin Dosing

Introduction

The emergency department (ED) plays a critical role in the management of life-threatening infection. Prior data suggest that ED vancomycin dosing is frequently inappropriate. The objective is to assess the impact of an electronic medical record (EMR) intervention designed to improve vancomycin dosing accuracy, on vancomycin dosing and clinical outcomes in critically ill ED patients.

Methods

Retrospective before-after cohort study of all patients (n=278) treated with vancomycin in a 60,000-visit Midwestern academic ED (March 2008 and April 2011) and admitted to an intensive care unit. The primary outcome was the proportion of vancomycin doses defined as “appropriate” based on recorded actual body weight. We also evaluated secondary outcomes of mortality and length of stay.

Results

The EMR dose calculation tool was associated with an increase in mean vancomycin dose ([14.1±5.0] vs. [16.5±5.7] mg/kg, p<0.001) and a 10.3% absolute improvement in first-dose appropriateness (34.3% vs. 24.0%, p=0.07). After controlling for age, gender, methicillin-resistant staphylococcus aureus infection, and Acute Physiology and Chronic Health Evaluation II score, 28-day in-hospital mortality (odds ratio OR 1.72; 95% CI [0.76–3.88], p=0.12) was not affected.

Conclusion

A computerized decision-support tool is associated with an increase in mean vancomycin dose in critically ill ED patients, but not with a statistically significant increase in therapeutic vancomycin doses. The impact of decision-support tools should be further explored to optimize compliance with accepted antibiotic guidelines and to potentially affect clinical outcome.

Microbiology, resistance patterns, and risk factors of mortality in ventilator-associated bacterial pneumonia in a Northern Thai tertiary-care university based general surgical intensive care unit

Background

Ventilator-associated pneumonia (VAP) occurrence, causative pathogens, and resistance patterns in surgical intensive care units (SICU) are different between Western and developing Asian countries. In Thailand, resistant organisms have progressively increased in the last decade. However, the evidence describing causes of VAP and its outcomes, especially secondary to resistant pathogens, in Asian developing countries’ SICUs is very limited. Therefore, the objective of this study was to describe the incidence, pathogen characteristics, and risk factors that impact mortality and patient survival following VAP in a tertiary Northern Thai SICU.

Methods

Between 2008 and 2012, VAP occurred in a total of 150 patients in Chiang Mai University’s general SICUs (6.3±2.8 cases per 1,000 mechanical ventilator days). The following clinical data were collected from 46 patients who died and 104 patients who survived: microbiologic results, susceptible patterns, and survival status at hospital discharge. Antimicrobial susceptibility patterns were classified as susceptible, multidrug resistant (MDR), extensively drug resistant (XDR), and pan-drug resistant (PDR). The hazard ratio (HR) was calculated for risk factor analysis.

Results

Regarding the microbiology, gram negative organisms were the major pathogens (n=142, 94.7%). The first three most common organisms were Acinetobacter baumannii (38.7% of all organisms, mortality 41.4%), Klebsiella pneumoniae (17.3%, mortality 30.8%), and Pseudomonas aeruginosa (16.7%, mortality 16%) respectively. The most common gram positive organism was Staphylococcus aureus (4.0%, mortality 50%). The median day of VAP occurrence were significantly different between the three groups (P<0.01): susceptible (day 4), MDR (day 5), and XDR (day 6.5). Only half of all VAP cases were caused by susceptible organisms. Antibiotic resistance was demonstrated by 49.3% of the gram negative organisms and 62.5% of the gram positive organisms. Extensive drug resistance was evident only in Acinetobacter baumannii (30.6%) and Pseudomonas aeruginosa (1.3%). No pan-drug resistance was found during surveillance. The significant HR risk factors were age (P=0.03), resistant organisms (P=0.04), XDR (P=0.02), and acute physiology and chronic health evaluation II score (<0.01). Acinetobacter baumannii (P=0.06) and intubation due to severe sepsis (P=0.08) demonstrated a trend toward a significant increase in the HR. On the other hand, there were significantly decreased HRs in trauma patients (P=0.01). Initial administration of appropriate antibiotic therapy had a tendency toward a significant decrease in the HR (P=0.08).

Conclusion

Gram negative organisms were the primary cause of bacterial VAP in Chiang Mai University’s general SICU. Resistant strains were present in half of all VAP cases and were associated with the day of VAP onset. Regarding risk factors, age, acute physiology, chronic health evaluation II score, resistant organisms (especially XDR), and being a non-trauma patient increased the risk of mortality.

Predictors of clinical success among a national Veterans Affairs cohort with methicillin-resistant Staphylococcus aureus pneumonia

BACKGROUND

The treatment of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is exceedingly complicated, which is concerning because of the high mortality rate associated with the infection. Identification of independent predictors of clinical success can optimize patient care by assisting clinicians in treatment decisions.

OBJECTIVES

Our goal was to identify independent predictors of clinical success in a national Veterans Affairs (VA) cohort of patients with MRSA pneumonia.

METHODS

A nested case-control study was conducted among a cohort of VA patients with MRSA pneumonia receiving linezolid or vancomycin between January 2002 and September 2010. Cases included those demonstrating clinical success, defined as discharge from the hospital or intensive care unit by day 14 after treatment initiation, in the absence of death, therapy change, or intubation by day 14. Control subjects represented nonsuccess, defined as therapy change, intubation, intensive care unit admission, readmission, or death between treatment initiation and day 14. The potential predictors assessed included treatment, patient demographic and admission characteristics, previous health care and medication exposures, comorbidities, and medical history. Odds ratios (ORs) and 95% CIs were calculated from logistic regression.

RESULTS

Our study included 2442 cases of clinical success and 1290 control subjects. Demographic characteristics varied between the clinical success and nonsuccess groups, including age, race, and region of facility. A current diagnosis of chronic respiratory disease (46% vs 42%) and diagnosis of pneumonia in the year before the MRSA pneumonia admission (37% vs 32%) were both more common in the clinical success group. Despite these significant differences, only 2 predictors of clinical success were identified in our study: previous complication of an implant or graft, including mechanical complications and infections, in the year before the MRSA pneumonia admission (adjusted OR, 1.55 [95% CI, 1.17-2.06]) and treatment with linezolid (adjusted OR, 1.53 [95% CI, 1.12-2.10]). Predictors of nonsuccess (adjusted OR [95% CI) included diagnosis of concomitant urinary tract infection (0.82 [0.70-0.96]), intravenous line (0.76 [0.66-0.89]), previous coagulopathy (0.74 [0.56-0.96]), previous amputation procedure (0.72 [0.53-0.98]), current coagulopathy diagnosis (0.71 [0.53-0.96]), dialysis (0.54 [0.38-0.76]), multiple inpatient procedures (0.53 [0.45-0.62]), inpatient surgery (0.48 [0.41-0.57]), and previous endocarditis (0.24 [0.07-0.81]).

CONCLUSIONS

MRSA pneumonia tends to affect patients with complex care, and identification of the predictors of clinical success is useful when considering different therapeutic approaches. In this national cohort of VA patients with MRSA pneumonia, treatment was the only modifiable variable predicting clinical success.

Comparative effectiveness of linezolid and vancomycin among a national veterans affairs cohort with methicillin-resistant Staphylococcus aureus pneumonia

STUDY OBJECTIVE

As variability in vancomycin dosing, susceptibility, and tolerability has driven the need to compare newer agents with vancomycin in real-world clinical settings, we sought to quantify the effectiveness of linezolid compared with vancomycin on clinical outcomes for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia.

DESIGN

Retrospective cohort study.

DATA SOURCE

Veterans Health Administration national databases.

PATIENTS

Adults admitted to Veterans Affairs hospitals between January 2002 and September 2010 with diagnosis codes for MRSA and pneumonia, plus initiation and receipt of at least 3 days of continuous intravenous vancomycin therapy (4943 patients) or intravenous or oral linezolid therapy (328 patients) while in the hospital.

MEASUREMENTS AND MAIN RESULTS

Propensity score-adjusted Cox proportional hazards regression models quantified the effect of linezolid compared with vancomycin on time to 30-day mortality (primary outcome), therapy change, hospital discharge, discharge from intensive care, intubation, 30-day readmission, and 30-day MRSA reinfection. In addition, a composite outcome of clinical success was defined as discharge from the hospital or intensive care unit by day 14 after treatment initiation, in the absence of death, therapy change, or intubation by day 14. Subgroup analyses were performed in a validated microbiology-confirmed MRSA subgroup and clinical subgroup meeting clinical criteria for infection. Although a number of baseline variables differed significantly between the vancomycin and linezolid treatment groups, balance was achieved within propensity score quintiles. A significantly lower rate of therapy change was observed in the linezolid group (adjusted hazard ratio [HR] 0.68, 95% confidence interval [CI] 0.48-0.96). The clinical success rate was significantly higher among patients treated with linezolid (adjusted HR 1.25, 95% CI 1.07-1.47). Comparable findings were observed in the subgroup analyses.

CONCLUSION

Individual clinical outcomes were similar among patients treated for MRSA pneumonia with linezolid compared with vancomycin. A significantly higher rate of the composite outcome of clinical success was observed, however, among patients treated with linezolid compared with vancomycin.

How important is methicillin-resistant Staphylococcus aureus as a cause of community-acquired pneumonia and what is best antimicrobial therapy?

The emergence of methicillin-resistant strains of Staphylococcus aureus has raised issues regarding the importance of methicillin-resistant S aureus (MRSA) in community-acquired pneumonia (CAP) and its optimal treatment. Community-acquired MRSA (CA-MRSA) is an important cause of CAP because of the high mortality if not suspected early, and its occurrence in young patients with long life expectancy. Certain clinical features can increase the probability of CA-MRSA as a cause of CAP. The consistent trend toward better outcomes for documented MRSA pneumonia suggests that linezolid be considered the drug of choice for documented MRSA CAP, especially for CA-MRSA.