Clinical and economic impact of methicillin resistance in patients with Staphylococcus aureus bacteremia

Time from Admission to the Onset of Methicillin-Resistant Staphylococcus aureus Bacteremia in a Single Acute Care Hospital in Japan

The spread of antimicrobial resistant organisms (AROs) poses a major threat to animal and human health. In Japan, the estimated disability-adjusted life years (DALYs) due to ARO infections is 137.9 per 100,000 persons, with methicillin-resistant Staphylococcus aureus (MRSA) being the main contributor. Factors that can contribute to DALYs in Japan include younger age and a higher number of deaths in patients with MRSA bacteremia. Moreover, longer hospital stays may contribute to the higher rates of MRSA bacteremia in Japan than in western countries. We reviewed the diagnostic procedure combination data collected from January 1, 2016 to December 31, 2020, in an acute care hospital in Tokyo, Japan. We found that the median time from admission to MRSA bacteremia onset was 26 days, which is longer than that observed in western countries however similar to that in South Korea. Furthermore, our cohort was older than those in the United States and South Korea, potentially contributing to the higher number of years of life lost in Japan. These results underscore the need to develop strategies to reduce hospitalization rates in Japan. Larger multicenter studies are needed to comprehensively evaluate the economic and health burdens of MRSA bacteremia in Japan.

Manuka honey as a non-antibiotic alternative against Staphylococcus spp. and their small colony variant (SCVs) phenotypes

The antibiotic resistance (ABR) crisis is an urgent global health priority. Staphylococci are among the problematic bacteria contributing to this emergency owing to their recalcitrance to many clinically important antibiotics. Staphylococcal pathogenesis is further complicated by the presence of small colony variants (SCVs), a bacterial subpopulation displaying atypical characteristics including retarded growth, prolific biofilm formation, heightened antibiotic tolerance, and enhanced intracellular persistence. These capabilities severely impede current chemotherapeutics, resulting in chronic infections, poor patient outcomes, and significant economic burden. Tackling ABR requires alternative measures beyond the conventional options that have dominated treatment regimens over the past 8 decades. Non-antibiotic therapies are gaining interest in this arena, including the use of honey, which despite having ancient therapeutic roots has now been reimagined as an alternative treatment beyond just traditional topical use, to include the treatment of an array of difficult-to-treat staphylococcal infections. This literature review focused on Manuka honey (MH) and its efficacy as an anti-staphylococcal treatment. We summarized the studies that have used this product and the technologies employed to study the antibacterial mechanisms that render MH a suitable agent for the management of problematic staphylococcal infections, including those involving staphylococcal SCVs. We also discussed the status of staphylococcal resistance development to MH and other factors that may impact its efficacy as an alternative therapy to help combat ABR.

The impact of methicillin resistance on clinical outcome among patients with Staphylococcus aureus osteomyelitis: a retrospective cohort study of 482 cases

This study was designed to evaluate the impact of methicillin resistance on the outcomes among patients with S. aureus osteomyelitis. We reviewed all extremity osteomyelitis patients treated in our clinic center between 2013 and 2020. All adult patients with S. aureus pathogen infection were included. Clinical outcome in terms of infection control, length of hospital stay, and complications were observed at the end of a 24-month follow-up and retrospectively analyzed between populations with/without methicillin resistance. In total, 482 osteomyelitis patients due to S. aureus were enrolled. The proportion of methicillin-resistant S. aureus (MRSA) was 17% (82) and 83% (400) of patients had Methicillin-sensitive S. aureus (MSSA). Of 482 patients, 13.7% (66) presented with infection persistence after initial debridement and antibiotic treatment (6 weeks), needed repeated debridement, 8.5% (41) had recurrence after all treatment end and a period infection cure, complications were observed in 17 (3.5%) patients (pathologic fracture; 4, nonunion; 5, amputation; 8) at final follow-up. Following multivariate analysis, we found patients with S. aureus osteomyelitis due to MRSA are more likely to develop a persistent infection (OR: 2.26; 95% CI 1.24-4.13) compared to patients with MSSA. Patients infected with MRSA also suffered more complications (8.5% vs. 2.5%, p = 0.015) and longer hospital stays (median: 32 vs. 23 days, p < 0.001). No statistically significant differences were found in recurrence. The data indicated Methicillin resistance had adverse clinical implication for infection persistence among patients with S. aureus osteomyelitis. These results will help for patients counsel and preparation for treatment.

The burden of carbapenem-resistant Enterobacterales infection in a large Thai tertiary care hospital

Background: Carbapenem-resistant Enterobacterales (CRE) are resistant to several other classes of antimicrobials, reducing treatment options and increasing mortality. We studied the clinical characteristics and burden of hospitalized adult patients with CRE infections in a setting where treatment options are limited.

Methods: A retrospective cohort study included adult inpatients between January 2015–December 2019 at Siriraj Hospital in Bangkok, Thailand. Clinical and microbiological data were reviewed.

Results: Of 420 patients with CRE infections, the mean age was 65.00 ± 18.89 years, 192 (45.72%) were male, and 112 (26.90%) were critically ill. Three hundred and eighty (90.48%) had Klebsiella pneumoniae, and 40 (9.52%) had Escherichia coli infections. The mean APACHE II score was 14.27 ± 6.36. Nearly half had previous hospitalizations (48.81%), 41.2% received antimicrobials, and 88.1% had undergone medical procedures before the onset of infection. The median time of onset of CRE infection was 16 days after admission. Common sites of infection were bacteremia (53.90%) and pneumonia (45.47%). Most CRE-infected patients had septic shock (63.10%) and Gram-negative co-infections (62.85%). Colistin (29.95%) and non-colistin (12.91%) monotherapies, and colistin-based (44.78%) and non-colistin-based (12.36%) combination therapies were the best available antimicrobial therapies (BAAT). The median length of hospitalization was 31 days, and the median hospitalization cost was US$10,435. The in-hospital mortality rate was 68.33%. Septic shock [adjusted odds ratio (aOR) 10.73, 5.65–20.42, p <0 .001], coinfection (aOR 2.43, 1.32–4.47, p = 0.004), mechanical ventilation (aOR 2.33, 1.24–4.36, p = 0.009), and a high SOFA score at onset (aOR 1.18, 1.07–1.30, p <0 .001) were associated with mortality.

Conclusion: CRE infection increases mortality, hospital stays, and healthcare costs. A colistin-based regimen was the BAAT in this study. Therefore, newer antimicrobial agents are urgently needed.

Microbiological, Clinical and Radiological Aspects of Diabetic Foot Ulcers Infected with Methicillin-Resistant and -Sensitive Staphylococcus aureus

Diabetic foot ulcer (DFU) is one of the most common chronic complications of diabetes. This study aimed to assess the factors with an impact on the infection of diabetic foot ulcers by methicillin-resistant S. aureus and to evaluate the influence of methicillin resistance on the frequency of osteitis (based on classic X-ray images). A total of 863 patients suffering from DFU were analyzed during the study period. Out of 201 isolated S. aureus cases, 31 (15.4%) were methicillin-resistant (MRSA). MRSA infections were associated with a higher incidence of osteitis compared to MSSA infections (p << 0.0001), both the occurrence of smaller (<50%)) and greater (>50%) inflammatory bone changes (p << 0.0001). Furthermore, MRSA occurred significantly more frequently in men than in women (p < 0.01) and more often among patients with type 2 diabetes than among patients with type 1 diabetes (p < 0.05). MRSA were isolated statistically less often in overweight patients than in patients with normal BMI (p < 0.05). DFUs infected with MRSA were significantly more frequently associated with the presence of Pseudomonas sp. and other non-fermenting bacilli than those infected with MSSA (p < 0.05). To conclude, osteitis incidence is related to MRSA infection in patients with diabetic foot ulcers; thus, patients infected by S. aureus should be closely monitored in the course of using antibiotics and treated with narrow-spectrum antibiotics.

Automated Susceptibility Testing With Vitek 2 Compared to MicroScan Reduces Vancomycin Alternative Therapy For Methicillin-Resistant Staphylococcus Aureus Bacteremia

OBJECTIVES

Variability in minimum inhibitory concentration (MIC) with automated susceptibility testing instruments may influence methicillin-resistant Staphylococcus aureus (MRSA) treatment. The purpose of this study was to evaluate the difference in vancomycin MIC values and the impact on vancomycin alternative therapy for MRSA bacteremia using the MicroScan and VITEK 2 automated systems.

METHODS

This was a retrospective multicenter cohort study of adult patients with MRSA bacteremia. Patients were stratified by susceptibility testing with MicroScan (May 2013-December 2016) or VITEK 2 (June 2017-February 2020). The primary outcome was vancomycin alternative therapy use. Secondary endpoints included MRSA MIC, 30-day mortality, 30- and 90-day readmission, and hospital length of stay (LOS).

RESULTS

A total of 193 patients were included for analysis: 89 in the MicroScan group and 104 in the VITEK 2 group. Vancomycin alternative therapy use was higher in the MicroScan group than the VITEK 2 group (56.2% vs 20.2%; p <0.001). Median MIC value was 2 mg/L and 1 mg/L for MicroScan and VITEK 2, respectively (p <0.001). Median hospital LOS was shorter in the VITEK 2 period (16 vs 12 days; p = 0.02). Thirty-day mortality (10.1% vs 7.7%; p = 0.555) and 90-day readmission (34.8% vs 29.8%; p = 0.457) did not significantly differ between MicroScan and VITEK 2 groups.

CONCLUSIONS

VITEK 2 use was associated with lower reported vancomycin MICs and less use of vancomycin alternative therapy.

Therapeutic Drug Monitoring of Vancomycin in Adult Patients with Methicillin-Resistant Staphylococcus aureus Bacteremia or Pneumonia

Background

Vancomycin remains widely used for methicillin-resistant Staphylococcus aureus (MRSA) infections; however, treatment failure rates up to 50% have been reported. At the authors' institution, monitoring of trough concentration is the standard of care for therapeutic drug monitoring of vancomycin. New guidelines support use of the ratio of 24-hour area under the concentration-time curve to minimum inhibitory concentration (AUC₂₄/MIC) as the pharmacodynamic index most likely to predict outcomes in patients with MRSA-associated infections.

Objectives

To determine the discordance rate between trough levels and AUC₂₄/MIC values and how treatment failure and nephrotoxicity outcomes compare between those achieving and not achieving their pharmacodynamic targets.

Methods

This retrospective cohort study involved patients with MRSA bacteremia or pneumonia admitted to the study hospital between March 1, 2014, and December 31, 2018, and treated with vancomycin. Data for trough concentrations were collected, and minimum concentrations (C _min) were extrapolated. The AUC₂₄/MIC values were determined using validated population pharmacokinetic models. The C _min and AUC₂₄/MIC values were characterized as below, within, or above pharmacodynamic targets (15-20 mg/L and 400-600, respectively). Discordance was defined as any instance where a patient's paired C _min and AUC₂₄/MIC values fell in different ranges (i.e., below, within, or above) relative to the target ranges. Predictors of treatment failure and nephrotoxicity were determined using logistic regression.

Results

A total of 128 patients were included in the analyses. Of these, 73 (57%) received an initial vancomycin dose less than 15 mg/kg. The discordance rate between C _min and AUC₂₄/MIC values was 21% (27/128). Rates of treatment failure and nephrotoxicity were 34% (43/128) and 18% (23/128), respectively. No clinical variables were found to predict discordance. Logistic regression identified initiation of vancomycin after a positive culture result (odds ratio [OR] 4.41, 95% confidence interval [CI] 1.36-14.3) and achievement of target AUC₂₄/MIC after 4 days (OR 3.48, 95% CI 1.39-8.70) as modifiable predictors of treatment failure.

Conclusions

The relationship between vancomycin monitoring and outcome is likely confounded by inadequate empiric or initial dosing. Before any modification of practice with respect to vancomycin monitoring, empiric vancomycin dosing should be optimized.

De novo methicillin-resistant Staphylococcus aureus vs. methicillin-sensitive Staphylococcus aureus infections of the spine, similar clinical outcome, despite more severe presentation in surgical patients

Vertebral osteomyelitis (VO) is a severe infection of the vertebral body and the adjacent disc space, where Staphylococcus aureus is most commonly isolated. The objective of this retrospective study was to determine risk factors for and compare outcome differences between de novo methicillin-resistant Staphylococcus aureus (MRSA) VO and methicillin-sensitive Staphylococcus aureus (MSSA) VO. A retrospective cohort study was performed by review of the electronic medical records of 4541 consecutive spine surgery patients. Among these 37 underwent surgical treatment of de novo MRSA and MSSA spinal infections. Patient demographics, pre- and postoperative neurological status (ASIA impairment score), surgical treatment, inflammatory laboratory values, nutritional status, comorbidities, antibiotics, hospital stay, ICU stay, reoperation, readmission, and complications were collected. A minimum follow-up (FU) of 12 months was required. Among the 37 patients with de novo VO, 19 were MRSA and 18 were MSSA. Mean age was 52.4 and 52.9 years in the MRSA and MSSA groups, respectively. Neurological deficits were found in 53% of patients with MRSA infection and in 17% of the patients with MSSA infection, which was statistically significant (p < 0.05). Chronic renal insufficiency and malnutrition were found to be significant risk factors for MRSA VO. Preoperative albumin was significantly lower in the MRSA group (p < 0.05). Patients suffering from spinal infection with chronic renal insufficiency and malnutrition should be watched more carefully for MRSA. The MRSA group did not show a significant difference with regard to final clinical outcome despite more severe presentation.

Hand Infections: Epidemiology and Public Health Burden

Upper extremity infections are common. Most infections can be effectively treated with minor surgical procedures and/or oral antibiotics; however, inappropriate or delayed care can result in significant, long-term morbidity. The basic principles of treating hand infections were described more than a century ago and most remain relevant today. Immunosuppressant medications, chronic health conditions such as diabetes and human immunodeficiency virus, and public health problems like intravenous drug use, have changed the landscape of hand infections and provide new challenges in treatment.

Monotherapy with Vancomycin or Daptomycin versus Combination Therapy with β-Lactams in the Treatment of Methicillin-Resistant Staphylococcus Aureus Bloodstream Infections: A Retrospective Cohort Analysis

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI) are associated with high morbidity and mortality. More in vitro, in vivo, and clinical data suggest that vancomycin (VAN) or daptomycin (DAP) combination therapy with β-lactams (BL) improves outcomes of MRSA infections. We hypothesize that BL combination with VAN or DAP would reduce the odds of clinical failure compared to VAN or DAP monotherapy.

METHODS

A retrospective cohort study of adult patients ≥ 18 years treated with VAN or DAP for MRSA BSI from 2006 to 2019 at Detroit Medical Center. Combination therapy (CT) was defined as VAN or DAP plus any BL for ≥ 24 h within 72 h of index culture. Monotherapy (MT) was defined as ≥ 72 h VAN or DAP within 72 h of index culture and no BL for ≥ 24 h up to 7 days following VAN/DAP initiation. Primary outcome was composite endpoint of clinical failure defined as: (1) 30-day mortality, (2) 60-day recurrence, or (3) persistent bacteremia (PB). PB was defined as bacteremia > 5 days. Multivariable logistic regression was used to evaluate the association between CT and the primary outcome.

RESULTS

Overall, 597 patients were included in this analysis, 153 in the MT group and 444 in the CT group. CT was independently associated with reduced odds of clinical failure (adjusted odds ratio, 0.523; 95% confidence interval, 0.348-0.787). The composite endpoint was driven by 60-day recurrence and PB but not 30-day mortality. There were no difference in adverse events including nephrotoxicity between the two study arms.

CONCLUSIONS

In hospitalized adults with MRSA BSI, CT with any BL was independently associated with improved clinical outcomes and may ultimately be selected as preferred therapy.

Antagonistic Effect of Colistin on Vancomycin Activity against Methicillin-Resistant Staphylococcus aureus in In Vitro and In Vivo Studies

As concerns arise that the vancomycin MIC of methicillin-resistant Staphylococcus aureus (MRSA) could be increased by concurrent colistin administration, we evaluated the effect of colistin on vancomycin efficacy against MRSA via in vitro and in vivo studies. Among MRSA blood isolates collected in a tertiary-care hospital, we selected representative strains from community-associated MRSA strains (CA-MRSA; ST72-MRSA-SCCmec IV) and hospital-acquired MRSA strains (HA-MRSA; ST5-MRSA-SCCmec II). USA CA-MRSA (USA300), HA-MRSA (USA100), N315 (New York/Japan clone), and a MRSA standard strain (ATCC 43300) were used for comparison. We performed checkerboard assays to identify changes in the vancomycin MIC of MRSA following colistin exposure and evaluated the effect of a vancomycin-colistin combination using time-kill assays. We also assessed the in vivo antagonistic effect by administering vancomycin, colistin, and a combination of these two in a neutropenic murine thigh infection model. In the checkerboard assays, vancomycin MICs of all MRSA strains except N315 were increased by from 0.25 to 0.75 μg/ml following colistin exposure. However, the time-kill assays indicated antagonism only against ST5-MRSA and USA100, when the vancomycin concentration was twice the MIC. In the murine thigh infection model with ST5-MRSA and USA100, vancomycin monotherapy reduced the number of CFU/muscle >1 log₁₀ compared to a combination treatment after 24 h in ST5-MRSA, indicating an antagonistic effect of colistin on vancomycin treatment. This study suggests that exposure to colistin may reduce the susceptibility to vancomycin of certain MRSA strains. Combination therapy with vancomycin and colistin for multidrug-resistant pathogens might result in treatment failure for concurrent MRSA infection.

Clinical and economic impact of methicillin-resistant Staphylococcus aureus: a multicentre study in China

Methicillin-resistant Staphylococcus aureus (MRSA) has become a serious threat to global health. In China, the proportion of S. aureus isolates that were MRSA was 44.6% in 2014. The clinical and economic impact of MRSA in China remains largely uninvestigated. This study aims to compare the differences in hospital costs, length of hospital stay, and hospital mortality rate between MRSA and methicillin-susceptible S. aureus (MSSA) colonization or infection and between MRSA cases and those without an S. aureus infection. A retrospective and multicentre study was conducted in four tertiary hospitals in China between 2013 and 2015. Inpatient characteristics and hospital costs were collected from electronic medical records. We conducted propensity score matching (PSM) to eliminate selection bias by balancing the potential confounding variables between the two groups. The main indicators included hospital costs, length of hospital stay, and hospital mortality rate. A total of 1,335 inpatients with MRSA, 1,397 with MSSA, and 33,606 without an S. aureus infection were included. PSM obtained 954 and 1,313 pairs between the MRSA and MSSA groups and between the MRSA and S. aureus-free groups, respectively. After PSM, MRSA colonization or infection is associated with an increased total hospital cost ranging from $3,220 to $9,606, an excess length of hospital stay of 6 days–14 days, and an attributable hospital mortality rate of 0–3.58%. Between the MRSA and MSSA groups, MRSA colonization or infection was significantly associated with a higher total hospital cost and longer length of hospital stay among survivors but not among non-survivors; however, there were no differences in the hospital mortality rate between these two groups. Between the MRSA and the S. aureus-free groups, MRSA colonization or infection was significantly associated with an increased total hospital cost, a prolonged length of hospital stay and a higher hospital mortality rate among both survivors and non-survivors. It is critical to quantify the clinical and economic impact of MRSA to justify resource allocation for the development of strategies to improve clinical outcomes and to reduce the economic burden.

Reevaluation of the impact of methicillin-resistance on outcomes in patients with Staphylococcus aureus bacteremia and endocarditis

BACKGROUND/AIMS

Methicillin-resistant Staphylococcus aureus (MRSA) is highly prevalent in hospitals, and has recently emerged in the community. The impact of methicillin-resistance on mortality and medical costs for patients with S. aureus bacteremia (SAB) requires reevaluation.

METHODS

We searched studies with SAB or endocarditis using electronic databases including Ovid-Medline, Embase-Medline, and Cochrane Library, as well as five local databases for published studies during the period January 2000 to September 2011.

RESULTS

A total of 2,841 studies were identified, 62 of which involved 17,563 adult subjects and were selected as eligible. A significant increase in overall mortality associated with MRSA, compared to that with methicillin-susceptible S. aureus (MSSA), was evidenced by an odds ratio (OR) of 1.95 (95% confidence interval [CI], 1.73 to 2.21; p < 0.01). In 13 endocarditis studies, MRSA increased the risk of mortality, with an OR of 2.65 (95% CI, 1.46 to 4.80). When three studies, which compared mortality rates between CA-MRSA and CA-MSSA, were combined, the risk of methicillin-resistance increased 3.23-fold compared to MSSA (95% CI, 1.25 to 8.34). The length of hospital stay in the MRSA group was 10 days longer than that in the MSSA group (95% CI, 3.36 to 16.70). Of six studies that reported medical costs, two were included in the analysis, which estimated medical costs to be $9,954.58 (95% CI, 8,951.99 to 10,957.17).

CONCLUSION

MRSA is still associated with increased mortality, longer hospital stays and medical costs, compared with MSSA in SAB in studies published since the year 2000.

Economic burden of antibiotic resistance in ESKAPE organisms: a systematic review

Background

Antibiotic resistance (ABR) is one of the biggest threats to global health. Infections by ESKAPE (Enterococcus, S. aureus, K. pneumoniae, A. baumannii, P. aeruginosa, and E. coli) organisms are the leading cause of healthcare-acquired infections worldwide. ABR in ESKAPE organisms is usually associated with significant higher morbidity, mortality, as well as economic burden. Directing attention towards the ESKAPE organisms can help us to better combat the wide challenge of ABR, especially multi-drug resistance (MDR).

Objective

This study aims to systematically review and evaluate the evidence of the economic consequences of ABR or MDR ESKAPE organisms compared with susceptible cases or control patients without infection/colonization in order to determine the impact of ABR on economic burden.

Methods

Both English-language databases and Chinese-language databases up to 16 January, 2019 were searched to identify relevant studies assessing the economic burden of ABR. Studies reported hospital costs (charges) or antibiotic cost during the entire hospitalization and during the period before/after culture among patients with ABR or MDR ESKAPE organisms were included. The costs were converted into 2015 United States Dollars. Disagreements were resolved by a third reviewer.

Results

Of 13,693 studies identified, 83 eligible studies were included in our review. The most studied organism was S. aureus, followed by Enterococcus, A. baumannii, E. coli, E. coli or/and K. pneumoniae, P. aeruginosa, and K. pneumoniae. There were 71 studies on total hospital cost or charge, 12 on antibiotic cost, 11 on hospital cost or charge after culture, 4 on ICU cost, 2 on hospital cost or charge before culture, and 2 on total direct and indirect cost. In general, ABR or MDR ESKAPE organisms are significantly associated with higher economic burden than those with susceptible organisms or those without infection or colonization. Nonetheless, there were no differences in a few studies between the two groups on total hospital cost or charge (16 studies), antibiotic cost (one study), hospital cost before culture (one study), hospital cost after culture (one study). Even, one reported that costs associated with MSSA infection were higher than the costs for similar MRSA cases.

Conclusions

ABR in ESKAPE organisms is not always, but usually, associated with significantly higher economic burden. The results without significant differences may lack statistical power to detect a significant association. In addition, study design which controls for severity of illness and same empirical antibiotic therapy in the two groups would be expected to bias the study towards a similar, even negative result. The review also highlights key areas where further research is needed.

Prevalence, Influencing Factors, Antibiotic Resistance, Toxin and Molecular Characteristics of Staphylococcus aureus and MRSA Nasal Carriage among Diabetic Population in the United States, 2001-2004

Diabetic population were reported more likely to suffer carriage and infection with Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA) than non-diabetic population. We aim to elucidate the prevalence and characteristics of S. aureus and MRSA nasal carriage among diabetic population in the United States National Health and Nutrition Examination Survey, 2001-2004. Univariate analyses were conducted using Chi-square test, Fisher's exact probability test or student t test, as appropriate. Multivariate analy¬sis using logistic regression was conducted to assess the association between influencing factors and S. aureus and MRSA nasal carriage. 1010 diabetic participants were included in the study. The prevalence of S. aureus and MRSA nasal carriage were 28.32% and 1.09%, respec¬tively. After the logistic regression, ever had a painful sensation or tingling in hands or feet past three months (Odds Ratio [OR] = 0.359, 95% Confidence Interval [CI], 0.146-0.882) was significant among S. aureus nasal carriage and gender (OR = 3.410, 95% CI, 1.091-10.653) was significant among MRSA nasal carriage. The proportions of staphylococcal enterotoxin (SE) A, SEB, SEC, SED, Toxic-shock syn¬drome toxin-1, and Panton Valentine Leukocidin toxin among S. aureus strains were 18.75%, 3.13%, 12.50%, 15.63%, 28.13%, and 9.38%, respectively. 63.63% of MRSA strains were community-acquired, 27.27% were hospital-acquired, and 9.09% were non-typeable. Diabetic patients might be more likely to carry S. aureus and MRSA in the United States. Improving hand hygiene compliance, reducing antibiotic overuse, screening for carriers, and decolonization are recommended to reduce the spread of S. aureus and MRSA, especially in community.

Self-medication of antibiotics: investigating practice among university students at the Malaysian National Defence University

Background: Self-medication of drugs to alleviate symptoms is a common global behavior, helping relieve burdens on health services, but many drugs eg, antibiotics are prescription-only. Self-medication of antibiotics (SMA) is an irrational use of drugs, contributing to microbial resistance increasing health care costs and higher mortality and morbidity. This study aimed to assess SMA among university students. Methods: This was a cross-sectional study conducted among medical and non-medical students of the National Defence University of Malaysia. A validated instrument was used to gather data. Ethics approval was obtained. Random and universal sampling was adopted, and SPSS 21 was used for data analysis. Results: A total of 649 students participated in the study: 48.5% male and 51.5% female, 39.3% reported self-medicating with antibiotics. Penicillin, doxycycline, clarithromycin were the antibiotics most used with the majority reporting no adverse drug reactions. Cost savings and convenience were the principal reasons for SMA which were mainly obtained from local retail pharmacies. Despite medical students (particularly the more senior) having better knowledge of antibiotic use than non-medical students, 89% of all research participants responded that practicing SMA was a good/acceptable practice. Conclusion: SMA is common amongst Malaysian students and, despite understanding why SMA is unwise, even medical students self-medicate.

The Impact of Concomitant Empiric Cefepime on Patient Outcomes of Methicillin-Resistant Staphylococcus aureus Bloodstream Infections Treated With Vancomycin

Background

Data suggest that vancomycin + β-lactam combinations improve clearance of methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSIs). However, it is unclear which specific β-lactams confer benefit. This analysis evaluates the impact of concomitant empiric cefepime on outcomes of MRSA BSIs treated with vancomycin.

Methods

Retrospective cohort study of adults with MRSA BSI from 2006 to 2017. Vancomycin + cefepime therapy was defined as ≥24 hours of cefepime during the first 72 hours of vancomycin. The primary outcome was microbiologic failure, defined as BSI duration ≥7 days and/or 60-day recurrence. Multivariable logistic regression was used to evaluate the association between vancomycin + cefepime therapy and binary outcomes. Cause-specific and subdistribution hazard models were used to evaluate the association between vancomycin + cefepime and BSI clearance.

Results

Three hundred fifty-eight patients were included, 129 vancomycin and 229 vancomycin + cefepime. Vancomycin + cefepime therapy was independently associated with reduced microbiologic failure (adjusted odds ratio [aOR], 0.488; 95% confidence interval [CI], 0.271–0.741). This was driven by a reduction in the incidence of BSI durations ≥7 days (vancomycin + cefepime aOR, 0.354; 95% CI, 0.202–0.621). Vancomycin + cefepime had no association with 30-day mortality (aOR, 0.952; 95% CI, 0.435–2.425). Vancomycin + cefepime was associated with faster BSI clearance in both cause-specific (HR, 1.408; 95% CI, 1.125–1.762) and subdistribution hazard models (HR, 1.264; 95% CI, 1.040–1.536).

Conclusions

Concomitant empiric cefepime improved MRSA BSI clearance and may be useful as the β-lactam component of synergistic vancomycin + β-lactam regimens when empiric or directed gram-negative coverage is desired.

[Current status of antibiotic therapy for Staphylococcus aureus sepsis in children]

OBJECTIVE

To investigate the current status of empirical antibiotic therapy for children with Staphylococcus aureus sepsis and the effect of therapeutic paradigm on prognosis based on a retrospective analysis.

METHODS

A total of 78 children with Staphylococcus aureus sepsis who were admitted from January 2014 to August 2017 were enrolled. According to the preferred empirical antibiotics before the detection of Staphylococcus aureus by blood culture, these children were divided into a carbapenem group with 16 children, a β-lactam group with 37 children, a vancomycin group with 15 children and a vancomycin+β-lactam group with 10 children. A retrospective analysis was performed for related clinical data including general status, underlying diseases, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, history of use of immunosuppressant, drug resistance to methicillin and prognosis. A logistic regression analysis was used to investigate the effect of empirical antibiotic therapy on the clinical outcome and prognosis of children with Staphylococcus aureus sepsis.

RESULTS

There were no significant differences among these groups in general status, underlying diseases, history of use of immunosuppressant, APACHE II score, nosocomial infection and detection rate of methicillin-resistant Staphylococcus aureus (P>0.05). There were significant differences in the incidence rate of septic shock and in-hospital mortality among these four groups (P<0.05). The carbapenem group had the highest incidence rate of septic shock and in-hospital mortality (69% and 50% respectively). The multivariate logistic regression analysis showed that empirical antibiotic therapy with different antibiotics had different risks for septic shock and in-hospital death in children with Staphylococcus aureus sepsis (P<0.05), and that an APACHE II score of ≥15 was an independent risk factor for septic shock in these children (P<0.05). The carbapenem group had significantly higher risks of septic shock and in-hospital death than the vancomycin group (P<0.05).

CONCLUSIONS

Inappropriate empirical use of antibiotics may lead to a poor prognosis in children with Staphylococcus aureus sepsis. Empirical use of carbapenems is not recommended for children suspected of Staphylococcus aureus sepsis.

National Costs Associated With Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus Hospitalizations in the United States, 2010-2014

Background

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) have been associated with worse patient outcomes and higher costs of care than methicillin-susceptible (MSSA) infections. However, since prior studies found these differences, the healthcare landscape has changed, including widespread dissemination of community-associated strains of MRSA. We sought to provide updated estimates of the excess costs of MRSA infections.

Methods

We conducted a retrospective analysis using data from the National Inpatient Sample from the Agency for Healthcare Research and Quality for the years 2010-2014. We calculated costs for hospitalizations, including MRSA- and MSSA-related septicemia and pneumonia infections, as well as MRSA- and MSSA-related infections from conditions classified elsewhere and of an unspecified site ("other infections"). Differences in the costs of hospitalization were estimated using propensity score-adjusted mortality outcomes for 2010-2014.

Results

In 2014, estimated costs were highest for pneumonia and sepsis-related hospitalizations. Propensity score-adjusted costs were significantly higher for MSSA-related pneumonia ($40725 vs $38561; P = .045) and other hospitalizations ($15578 vs $14792; P < .001) than for MRSA-related hospitalizations. Similar patterns were observed from 2010 to 2013, although crude cost differences between MSSA- and MRSA-related pneumonia hospitalizations rose from 25.8% in 2010 to 31.0% in 2014. Compared with MSSA-related hospitalizations, MRSA-related hospitalizations had a higher adjusted mortality rate.

Conclusions

Although MRSA infections had been previously associated with higher hospitalization costs, our results suggest that, in recent years, costs associated with MSSA-related infections have converged with and may surpass costs of similar MRSA-related hospitalizations.

Effects of pharmacist intervention in Vancomycin treatment for patients with bacteremia due to Methicillin-resistant Staphylococcus aureus

Objective

We conducted a retrospective study based on composite endpoints for treatment failure to evaluate the effect of pharmacist-led VCM initial dose planning for Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia patients.

Methods

A retrospective cohort study was performed between pharmacist intervention and non-intervention groups. In this study, four types of failure were defined as the composite endpoint. When any one of the following failures occurred: 1) Death within 30 days from the start of VCM therapy, 2) Positive blood culture 7 days after the start of VCM therapy, 3) Change of VCM to another anti-MRSA agent, and 4) Development of nephrotoxicity, we considered that VCM treatment had failed. Survival time analysis was conducted with the Kaplan-Meier method and Cox’s proportional hazard model that included seven predefined parameters: pharmacist intervention, age, sex, weight, baseline VCM trough concentration, Charlson Comorbidity Index (CCI), and Pitt Bacteremia score (PBS). The effect of pharmacist intervention was studied as the survival probability estimated from the period of time from the start of VCM administration to the earliest failure.

Results

The survival rate at 30 days after starting VCM therapy, at the end of follow-up, was 53.1 and 82.1% in the non-intervention and intervention groups, respectively. A significant survival time prolongation was noted in the intervention group (p = 0.011, log rank test). Among the seven parameters, only pharmacist intervention was significantly different and its hazard ratio was 0.26 (p = 0.014). The survival probability of the intervention group was higher than that of the non-intervention group for the time to each failure. In subgroup analyses, a significant difference was noted in male patients between the intervention and non-intervention groups (p = 0.005). Age was categorized into those under and over 65 years old. For those over 65 years old, a significant difference was shown between the groups (p = 0.018).

Conclusion

To our knowledge, this is the first study to evaluate the failure of VCM treatment based on the composite endpoint. Pharmacist intervention through the initial VCM dose planning could maintain a balance between the efficacy and safety of VCM treatment and might avoid treatment failure for patients with MRSA bacteremia. Further investigations with large sample sizes are required to confirm our findings.

Clinical predictors of methicillin-resistance and their impact on mortality associated with Staphylococcus aureus bacteraemia

We investigated the clinical predictors of methicillin-resistance and their impact on mortality in 371 patients with Staphylococcus aureus bacteraemia identified from two prospective multi-centre studies. Methicillin resistant S. aureus (MRSA) accounted for 42.2% of community-onset and 74.5% of hospital-onset cases. No significant clinical difference was found between patients infected with MRSA vs. methicillin-sensitive S. aureus (MSSA), except that the former were more likely to have had hospital-onset bacteraemia and received antibiotics in the preceding 90 days. After stratifying according to the acquisition site, prior antibiotic use was the only independent predictor of having MRSA in both community-onset and hospital-onset cases. The frequency of inappropriate empirical antibiotic therapy was higher in patients with MRSA than in those with MSSA bacteraemia. However, methicillin resistance was not a predictor of mortality in patients and the clinical characteristics and outcomes of both MRSA and MSSA bacteraemia were similar. This study indicates that there are no definitive clinical or epidemiological risk factors which could distinguish MRSA from MSSA cases with the exception of the previous use of antibiotics for having MRSA bacteraemia, which emphasises the prudent use of glycopeptide treatment of patients at risk for invasive MRSA infections.

Multicenter Observational Study of Ceftaroline Fosamil for Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

Novel therapies for methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) are needed in the setting of reduced antibiotic susceptibilities and therapeutic failure. Ceftaroline is a cephalosporin antibiotic with MRSA activity. Although not FDA approved for MRSA BSI, ceftaroline has generated much interest as a potential treatment option. However, detailed descriptions of its use in this setting remain limited. To address this, we conducted a retrospective, multicenter, observational study of adult patients with MRSA BSI treated with at least 72 h of ceftaroline from 2011 to 2015. Safety outcomes were examined in the overall cohort, while efficacy outcomes were examined among patients who had not cleared their BSI prior to ceftaroline initiation. Data were also stratified by ceftaroline monotherapy or combination therapy. Predictors of clinical failure on ceftaroline treatment were also sought. Overall, 211 patients were included in the safety population; Clostridium difficile infection, rash, and neutropenia occurred in 6 patients (2.8%), 7 patients (3.3%), and 3 patients (1.4%), respectively. Clinical success was observed in 86 (68.3%) of the 126 patients included in the efficacy population. The monotherapy and combination therapy subgroups had similar proportions of patients experiencing success (69.7 and 64.9%, respectively). The median BSI durations post-ceftaroline treatment were 2 days (interquartile range, 1 to 4 days) for monotherapy and 3 days (interquartile range, 1.5 to 5 days) for combination therapy. Higher acute physiology and chronic health evaluation II scores and comorbid malignancy independently predicted treatment failure. Ceftaroline appears effective for MRSA BSI as both monotherapy and combination therapy. However, comparative studies are needed to further delineate the role of ceftaroline in MRSA BSI treatment.

Potential economic burden of carbapenem-resistant Enterobacteriaceae (CRE) in the United States

OBJECTIVES

The Centers for Disease Control and Prevention considers carbapenem-resistant Enterobacteriaceae (CRE) an urgent public health threat; however, its economic burden is unknown.

METHODS

We developed a CRE clinical and economics outcomes model to determine the cost of CRE infection from the hospital, third-party payer, and societal, perspectives and to evaluate the health and economic burden of CRE to the USA.

RESULTS

Depending on the infection type, the median cost of a single CRE infection can range from $22 484 to $66 031 for hospitals, $10 440 to $31 621 for third-party payers, and $37 778 to $83 512 for society. An infection incidence of 2.93 per 100 000 population in the USA (9418 infections) would cost hospitals $275 million (95% CR $217-334 million), third-party payers $147 million (95% CR $129-172 million), and society $553 million (95% CR $303-1593 million) with a 25% attributable mortality, and would result in the loss of 8841 (95% CR 5805-12 420) quality-adjusted life years. An incidence of 15 per 100 000 (48 213 infections) would cost hospitals $1.4 billion (95% CR $1.1-1.7 billion), third-party payers $0.8 billion (95% CR $0.6-0.8 billion), and society $2.8 billion (95% CR $1.6-8.2 billion), and result in the loss of 45 261 quality-adjusted life years.

CONCLUSIONS

The cost of CRE is higher than the annual cost of many chronic diseases and of many acute diseases. Costs rise proportionally with the incidence of CRE, increasing by 2.0 times, 3.4 times, and 5.1 times for incidence rates of 6, 10, and 15 per 100 000 persons.

A novel combination approach of human polyclonal IVIG and antibiotics against multidrug-resistant Gram-positive bacteria

Background

Gram-positive bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA) and enterococci, have shown a remarkable ability to develop resistance to antimicrobial agents.

Objective

We aimed to assess possible enhancement of the antimicrobial activity of vancomycin, amoxicillin, clarithromycin, and azithromycin by human polyclonal intravenous immunoglobulin G (IVIG) against 34 multidrug-resistant (MDR) bacterial isolates, including MRSA, Enterococcus faecium, and Enterococcus faecalis.

Materials and methods

Double combinations of the antibiotics with the IVIG were assessed by checkerboard assay, where the interaction was evaluated with respect to the minimum inhibitory concentration (MIC) of the antibiotics. The results of the checkerboard assay were verified in vitro using time-kill assay and in vivo using an invasive sepsis murine model.

Results

The checkerboard assay showed that IVIG enhanced the antimicrobial activity of amoxicillin and clarithromycin against isolates from the three groups of bacteria, which were resistant to the same antibiotics when tested in the absence of IVIG. The efficacy of vancomycin against 15% of the tested isolates was enhanced when it was combined with the antibodies. Antagonism was demonstrated in 47% of the E. faecalis isolates when clarithromycin was combined with the IVIG. Synergism was proved in the time-kill assay when amoxicillin was combined with the antibodies; meanwhile, antagonism was not demonstrated in all tested combinations, even in combinations that showed such response in checkerboard assay.

Conclusion

The suggested approach is promising and could be helpful to enhance the antimicrobial activity of not only effective antibiotics but also antibiotics that have been proven to be ineffective against MDR bacteria. To our knowledge, this combinatorial approach against MDR bacteria, such as MRSA and enterococci, has not been investigated before.

Beyond the Intensive Care Unit (ICU): Countywide Impact of Universal ICU Staphylococcus aureus Decolonization

A recent trial showed that universal decolonization in adult intensive care units (ICUs) resulted in greater reductions in all bloodstream infections and clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) than either targeted decolonization or screening and isolation. Since regional health-care facilities are highly interconnected through patient-sharing, focusing on individual ICUs may miss the broader impact of decolonization. Using our Regional Healthcare Ecosystem Analyst simulation model of all health-care facilities in Orange County, California, we evaluated the impact of chlorhexidine baths and mupirocin on all ICU admissions when universal decolonization was implemented for 25%, 50%, 75%, and 100% of ICU beds countywide (compared with screening and contact precautions). Direct benefits were substantial in ICUs implementing decolonization (a median 60% relative reduction in MRSA prevalence). When 100% of countywide ICU beds were decolonized, there were spillover effects in general wards, long-term acute-care facilities, and nursing homes resulting in median 8.0%, 3.0%, and 1.9% relative MRSA reductions at 1 year, respectively. MRSA prevalence decreased by a relative 3.2% countywide, with similar effects for methicillin-susceptible S. aureus. We showed that a large proportion of decolonization's benefits are missed when accounting only for ICU impact. Approximately 70% of the countywide cases of MRSA carriage averted after 1 year of universal ICU decolonization were outside the ICU.

Cost-effectiveness of strategies to prevent methicillin-resistant Staphylococcus aureus transmission and infection in an intensive care unit

OBJECTIVE To create a national policy model to evaluate the projected cost-effectiveness of multiple hospital-based strategies to prevent methicillin-resistant Staphylococcus aureus (MRSA) transmission and infection. DESIGN Cost-effectiveness analysis using a Markov microsimulation model that simulates the natural history of MRSA acquisition and infection. PATIENTS AND SETTING Hypothetical cohort of 10,000 adult patients admitted to a US intensive care unit. METHODS We compared 7 strategies to standard precautions using a hospital perspective: (1) active surveillance cultures; (2) active surveillance cultures plus selective decolonization; (3) universal contact precautions (UCP); (4) universal chlorhexidine gluconate baths; (5) universal decolonization; (6) UCP + chlorhexidine gluconate baths; and (7) UCP+decolonization. For each strategy, both efficacy and compliance were considered. Outcomes of interest were: (1) MRSA colonization averted; (2) MRSA infection averted; (3) incremental cost per colonization averted; (4) incremental cost per infection averted. RESULTS A total of 1989 cases of colonization and 544 MRSA invasive infections occurred under standard precautions per 10,000 patients. Universal decolonization was the least expensive strategy and was more effective compared with all strategies except UCP+decolonization and UCP+chlorhexidine gluconate. UCP+decolonization was more effective than universal decolonization but would cost $2469 per colonization averted and $9007 per infection averted. If MRSA colonization prevalence decreases from 12% to 5%, active surveillance cultures plus selective decolonization becomes the least expensive strategy. CONCLUSIONS Universal decolonization is cost-saving, preventing 44% of cases of MRSA colonization and 45% of cases of MRSA infection. Our model provides useful guidance for decision makers choosing between multiple available hospital-based strategies to prevent MRSA transmission.

Universal vs Risk Factor Screening for Methicillin-Resistant Staphylococcus aureus in a Large Multicenter Tertiary Care Facility in Canada

OBJECTIVE To assess the clinical effectiveness of a universal screening program compared with a risk factor-based program in reducing the rates of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) among admitted patients at the Ottawa Hospital. DESIGN Quasi-experimental study. SETTING Ottawa Hospital, a multicenter tertiary care facility with 3 main campuses, approximately 47,000 admissions per year, and 1,200 beds. METHODS From January 1, 2006 through December 31, 2007 (24 months), admitted patients underwent risk factor-based MRSA screening. From January 1, 2008 through August 31, 2009 (20 months), all patients admitted underwent universal MRSA screening. To measure the effectiveness of this intervention, segmented regression modeling was used to examine monthly nosocomial MRSA incidence rates per 100,000 patient-days before and during the intervention period. To assess secular trends, nosocomial Clostridium difficile infection, mupirocin prescriptions, and regional MRSA rates were investigated as controls. RESULTS The nosocomial MRSA incidence rate was 46.79 cases per 100,000 patient-days, with no significant differences before and after intervention. The MRSA detection rate per 1,000 admissions increased from 9.8 during risk factor-based screening to 26.2 during universal screening. A total of 644 new nosocomial MRSA cases were observed in 1,448,488 patient-days, 323 during risk factor-based screening and 321 during universal screening. Secular trends in C. difficile infection rates and mupirocin prescriptions remained stable after the intervention whereas population-level MRSA rates decreased. CONCLUSION At Ottawa Hospital, the introduction of universal MRSA admission screening did not significantly affect the rates of nosocomial MRSA compared with risk factor-based screening. Infect. Control Hosp. Epidemiol. 2015;37(1):41-48.

Healthcare Associated Infections of Methicillin-Resistant Staphylococcus aureus: A Case-Control-Control Study

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most widespread and dangerous pathogens in healthcare settings. We carried out this case-control-control study at a tertiary care hospital in Guangzhou, China, to examine the antimicrobial susceptibility patterns, risk factors and clinical outcomes of MRSA infections.

METHODS

A total of 57 MRSA patients, 116 methicillin-susceptible Staphylococcus aureus (MSSA) patients and 102 S. aureus negative patients were included in this study. We applied the disk diffusion method to compare the antimicrobial susceptibilities of 18 antibiotics between MRSA and MSSA isolates. Risk factors of MRSA infections were evaluated using univariate and multivariate logistic regression models. We used Cox proportional hazards models and logistic regression analysis to assess the hospital stay duration and fatality for patients with MRSA infections.

RESULTS

The MRSA group had significantly higher resistance rates for most drugs tested compared with the MSSA group. Using MSSA patients as controls, the following independent risk factors of MRSA infections were identified: 3 or more prior hospitalizations (OR 2.8, 95% CI 1.3-5.8, P = 0.007), chronic obstructive pulmonary disease (OR 5.9, 95% CI 1.7-20.7, P = 0.006), and use of a respirator (OR 3.6, 95% CI 1.0-12.9, P = 0.046). With the S. aureus negative patients as controls, use of a respirator (OR 3.8, 95% CI 1.0-13.9, P = 0.047) and tracheal intubation (OR 8.2, 95% CI 1.5-45.1, P = 0.016) were significant risk factors for MRSA infections. MRSA patients had a longer hospital stay duration and higher fatality in comparison with those in the two control groups.

CONCLUSIONS

MRSA infections substantially increase hospital stay duration and fatality. Thus, MRSA infections are serious issues in this healthcare setting and should receive more attention from clinicians.

More accurate measurement of vancomycin minimum inhibitory concentration indicates poor outcomes in meticillin-resistant Staphylococcus aureus bacteraemia

Meticillin-resistant Staphylococcus aureus (MRSA) is an important pathogen associated with community-acquired and nosocomial infections. The aim of this study was to validate the vancomycin (VAN) minimum inhibitory concentration (MIC) and administration of VAN that may affect the prognosis of patients with MRSA bacteraemia. In total, 140 clinical MRSA strains from blood cultures were collected from January 2009 to December 2013 at a university hospital in Tokyo (Japan). Patient background, their clinical situation and the susceptibility of isolates to anti-MRSA agents in all cases were reviewed, and factors contributing to 30-day mortality were analysed. Susceptibility to anti-MRSA agents was measured by a microdilution susceptibility testing method. The VAN MIC was further evaluated at 0.25 μg/mL intervals from 0.5 μg/mL to 2.0 μg/mL. Multiple logistic regression analysis revealed a 4-fold increase in mortality of patients with a VAN MIC ≥1.5 μg/mL [odds ratio (OR)=3.952, 95% confidence interval (CI) 1.471-10.614; P=0.006]. A one-score increase in the Charlson co-morbidity index resulted in a 1.2-fold increase in the risk of death (OR=1.199, 95% CI 1.054-1.364; P=0.006). However, no significant difference was found in the ratio of the VAN 24-h area under the concentration-time curve to MIC between VAN MIC ≥1.5 μg/mL and <1.5 μg/mL. A significant increase in the MICs of teicoplanin and daptomycin was observed in strains with high VAN MICs. For patients with high VAN MICs, administration of these anti-MRSA antibiotics may have a poor outcome owing to cross-resistance.

Multicenter study of health care cost of patients admitted to hospital with Staphylococcus aureus bacteremia: Impact of length of stay and intensity of care

BACKGROUND

Methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S aureus bacteremia (SAB) have both been associated with high morbidity and mortality and heavy consumption of health care resources. We compared clinical and economic data for hospitalized cases of SAB in the context of a publicly funded health care system.

METHODS

A cost analysis was undertaken on an adult cohort of patients from 4 hospitals with SAB diagnosed within 3 days of hospitalization. Primary outcome was direct cost of inpatient care per case, determined at discharge and itemized using a standardized methodology.

RESULTS

A total of 435 patients were admitted with SAB; 58 had methicillin-resistant S aureus (MRSA). The median length of stay was similar in patients with MRSA and MSSA. There was no significant difference between the groups for mortality. Median direct medical costs of SAB were $12,078. Patients with MRSA had 1.32 times higher direct costs than MSSA. A similar estimate was derived using a propensity score approach (P = .148). Human health care resources comprised >70% of total costs per case, whereas antibiotics comprised 1%-2%.

CONCLUSION

Understanding the dynamics of resource consumption is critical to improving its efficiency and the quality of patient care. Our findings suggest that hospital length of stay and care intensity should be the major focus of any resource assessment exercise.

Synthesis and Biological Evaluation of N-Alkoxyphenyl-3-hydroxynaphthalene-2-carboxanilides

A series of fifteen new N-alkoxyphenylanilides of 3-hydroxynaphthalene-2-carboxylic acid was prepared and characterized. Primary in vitro screening of the synthesized compounds was performed against Staphylococcus aureus, three methicillin-resistant S. aureus strains, Mycobacterium tuberculosis H37Ra and M. avium subsp. paratuberculosis. Some of the tested compounds showed antibacterial and antimycobacterial activity against the tested strains comparable with or higher than that of the standards ampicillin or rifampicin. 3-Hydroxy-N-(2-propoxyphenyl)naphthalene-2-carboxamide and N-[2-(but-2-yloxy)-phenyl]-3-hydroxynaphthalene-2-carboxamide had MIC = 12 µM against all methicillin-resistant S. aureus strains; thus their activity is 4-fold higher than that of ampicillin. The second mentioned compound as well as 3-hydroxy-N-[3-(prop-2-yloxy)phenyl]-naphthalene-2-carboxamide had MICs = 23 µM and 24 µM against M. tuberculosis respectively. N-[2-(But-2-yloxy)phenyl]-3-hydroxynaphthalene-2-carboxamide demonstrated higher activity against M. avium subsp. paratuberculosis than rifampicin. Screening of the cytotoxicity of the most effective antimycobacterial compounds was performed using THP-1 cells, and no significant lethal effect was observed for the most potent compounds. The compounds were additionally tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. N-(3-Ethoxyphenyl)-3-hydroxynaphthalene-2-carboxamide (IC₅₀ = 4.5 µM) was the most active PET inhibitor. The structure-activity relationships are discussed.

Diagnosis and treatment of bacteremia and endocarditis due to Staphylococcus aureus. A clinical guideline from the Spanish Society of Clinical Microbiology and Infectious Diseases (SEIMC)

Both bacteremia and infective endocarditis caused by Staphylococcus aureus are common and severe diseases. The prognosis may darken not infrequently, especially in the presence of intracardiac devices or methicillin-resistance. Indeed, the optimization of the antimicrobial therapy is a key step in the outcome of these infections. The high rates of treatment failure and the increasing interest in the influence of vancomycin susceptibility in the outcome of infections caused by both methicillin-susceptible and -resistant isolates has led to the research of novel therapeutic schemes. Specifically, the interest raised in recent years on the new antimicrobials with activity against methicillin-resistant staphylococci has been also extended to infections caused by susceptible strains, which still carry the most important burden of infection. Recent clinical and experimental research has focused in the activity of new combinations of antimicrobials, their indication and role still being debatable. Also, the impact of an appropriate empirical antimicrobial treatment has acquired relevance in recent years. Finally, it is noteworthy the impact of the implementation of a systematic bundle of measures for improving the outcome. The aim of this clinical guideline is to provide an ensemble of recommendations in order to improve the treatment and prognosis of bacteremia and infective endocarditis caused by S. aureus, in accordance to the latest evidence published.

Evolutionary dynamics of methicillin-resistant Staphylococcus aureus within a healthcare system

BACKGROUND

In the past decade, several countries have seen gradual replacement of endemic multi-resistant healthcare-associated methicillin-resistant Staphylococcus aureus (MRSA) with clones that are more susceptible to antibiotic treatment. One example is Singapore, where MRSA ST239, the dominant clone since molecular profiling of MRSA began in the mid-1980s, has been replaced by ST22 isolates belonging to EMRSA-15, a recently emerged pandemic lineage originating from Europe.

RESULTS

We investigated the population structure of MRSA in Singaporean hospitals spanning three decades, using whole genome sequencing. Applying Bayesian phylogenetic methods we report that prior to the introduction of ST22, the ST239 MRSA population in Singapore originated from multiple introductions from the surrounding region; it was frequently transferred within the healthcare system resulting in a heterogeneous hospital population. Following the introduction of ST22 around the beginning of the millennium, this clone spread rapidly through Singaporean hospitals, supplanting the endemic ST239 population. Coalescent analysis revealed that although the genetic diversity of ST239 initially decreased as ST22 became more dominant, from 2007 onwards the genetic diversity of ST239 began to increase once more, which was not associated with the emergence of a sub-clone of ST239. Comparative genomic analysis of the accessory genome of the extant ST239 population identified that the Arginine Catabolic Mobile Element arose multiple times, thereby introducing genes associated with enhanced skin colonization into this population.

CONCLUSIONS

Our results clearly demonstrate that, alongside clinical practice and antibiotic usage, competition between clones also has an important role in driving the evolution of nosocomial pathogen populations.

Economic features of antibiotic resistance: the case of methicillin-resistant Staphylococcus aureus

This paper analyses and updates the economic information regarding methicillin-resistant Staphylococcus aureus (MRSA), including information that has been previously reviewed by other authors, and new information, for the purpose of facilitating health management and clinical decisions. The analysed articles reveal great disparity in the economic burden on MRSA patients; this is mainly due to the diversity of the designs of the studies, as well as the variability of the patients and the differences in health care systems. Regarding prophylactic strategies, the studies do not provide conclusive results that could unambiguously orientate health management. The studies addressing treatments noted that linezolid seems to be a cost-effective treatment for MRSA, mostly because it is associated with a shorter length of stay (LOS) in hospital. However, important variables such as antimicrobial susceptibility, infection type and resistance emergence should be included in these analyses before a conclusion is reached regarding which treatment is the best (most efficient). The reviewed studies found that rapid MRSA detection, using molecular techniques, is an efficient technique to control MRSA. As a general conclusion, the management of MRSA infections implicates important economic costs for hospitals, as they result in higher direct costs and longer LOS than those related to methicillin-susceptible S. aureus (MSSA) patients or MRSA-free patients; there is wide variability in those increased costs, depending on different variables. Moreover, the research reveals a lack of studies on other related topics, such as the economic implications of changes in MRSA epidemiology (community patients and lineages associated with farm animals).

Detection of methicillin-resistant staphylococci by biosensor assay consisting of nanoscale films on optical fiber long-period gratings

Methicillin-resistance among Staphylococcus species is a major health problem in hospitals, communities, and animals. There is a need for culture-free diagnostic assays that can be carried out rapidly, and maintain a high degree of sensitivity and specificity. To address this need an ionic self-assembled multilayer (ISAM) film was deposited on the surface of a long-period grating (LPG) optical fiber by immersion alternately in poly-allylamine hydrochloride and in poly-1-[p-(3'-carboxy-4'-hydroxyphenylazo) benzenesulfonamido]-1,2-ethandiyl (PCBS), resulting in terminal carboxyl groups on the LPG-ISAM. The terminal carboxyl groups were covalently conjugated to monoclonal antibodies (MAb) specific to penicillin-binding-protein 2a of methicillin resistant (MR) staphylococci. After exposure of the LPG-ISAM to 10(2) colony forming units (CFU)/ml of MR S. aureus (MRSA) for 50 min., light transmission was reduced by 19.7%. In contrast, after exposure to 10(6) CFU/ml of methicillin-sensitive S. aureus (MSSA) attenuation of light transmission was less than 1.8%. Exposure of the LPG-ISAM to extracts of liver, lungs, or spleen from mice infected with MRSA attenuated light transmission by 11.7-73.5%. In contrast, exposure of the biosensor to extracts from MSSA-infected mice resulted in 5.6% or less attenuation of light transmission. When the sensor was tested with 36 strains of MR staphylococci, 15 strains of methicillin-sensitive staphylococci, 10 strains of heterologous genera (all at 10(4) CFU/ml), or tissue samples from mice infected with MRSA, there was complete agreement between MR and non-MR bacteria determined by antibiotic susceptibility testing and the biosensor assay when the cutoff value for attenuation of light transmission was 6.3%. Thus, the biosensor described has the potential to detect MR staphylococci in clinical samples with a high degree of sensitivity and specificity.

Evaluation of the treatment of methicillin-resistant Staphylococcus aureus bacteremia

BACKGROUND

Bloodstream infections are a leading cause of death in the United States. Methicillin-resistant Staphylococcus aureus (MRSA) encompasses >50% of all S aureus strains in infected hospitalized patients and increases mortality, length of stay and healthcare costs. The objective of this study was to evaluate the treatment of MRSA bacteremia with daptomycin, linezolid and vancomycin.

METHODS

Patients with MRSA bacteremia between June 2008 and November 2010 were reviewed retrospectively. A microbiology laboratory report identified patients with ≥ 1 positive MRSA blood culture. Patients ≥ 18 years receiving daptomycin, linezolid or vancomycin for ≥ 7 consecutive days were included. Polymicrobial blood cultures and patients treated concomitantly with >1 anti-MRSA agent were excluded.

RESULTS

Of 122 patients included, 53 received daptomycin, 15 received linezolid and 54 received vancomycin. Clinical and microbiologic cure rates were similar between daptomycin, linezolid and vancomycin (58.5% versus 60% versus 61.1%; 93.6% versus 100% versus 90%, respectively). Thirteen patients (daptomycin 4/24 versus linezolid 1/9 versus vancomycin 8/49, P = 0.5960) had recurrence while 12 patients had re-infection (daptomycin 5/42 versus linezolid 0/9 versus vancomycin 7/49, P = 0.4755). Treatment failure occurred in 11 patients treated with daptomycin, 4 with linezolid and 9 with vancomycin (P = 0.662). Compared with daptomycin and vancomycin, linezolid-treated patients had higher mortality (P = 0.0186).

CONCLUSIONS

No difference in clinical or microbiologic cure rates was observed between groups. Daptomycin and vancomycin appear equally efficacious for MRSA bacteremia, whereas linezolid therapy was associated with higher mortality.

Surveillance cultures in healthcare-associated pneumonia: sense or nonsense?

PURPOSE OF REVIEW

This review explores the usefulness of surveillance cultures in healthcare-associated pneumonia (HCAP).

RECENT FINDINGS

The definition of HCAP is controversial. Causative micro-organisms of HCAP resemble those found in hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). Some types of surveillance cultures have proven useful in hospitalized patients. Whereas numerous studies have investigated the role of surveillance cultures in VAP, one may wonder whether surveillance culture implementation should belong in HCAP management guidelines.

SUMMARY

Studies exploring the usefulness of obtaining surveillance cultures in VAP are numerous, but are mostly retrospective, observational and/or quasi-experimental in nature. Surveillance cultures may be useful for antibiotic guidance, but positive predictive value and specificity of surveillance cultures are low, obviously negatively impacting on cost effectiveness, especially in the large population at risk for HCAP. On the other hand, multidrug-resistance is increasing and surveillance cultures for methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci in ICU-admitted patients appeared useful and cost-effective. Furthermore, surveillance cultures for the presence of multidrug-resistant Gram-negative bacilli might be useful for antibiotic guidance. Currently, neither community-acquired pneumonia, HCAP, HAP nor VAP guidelines incorporate surveillance cultures. In the future, surveillance cultures in populations at risk for HCAP may be able to differentiate HCAP from other kinds of pneumonia and authorize its reason for existence.

Real-Time Polymerase Chain Reaction Detection of Methicillin-ResistantStaphylococcus aureus:Impact on Nosocomial Transmission and Costs

Objectives.

To assess the impact of real-time polymerase chain reaction (PCR) detection of methicillin-resistantStaphylococcus aureus(MRSA) on nosocomial transmission and costs.

Design.

Monthly MRSA detection rates were measured from April 1, 2000, through December 31, 2005. Time series analysis was used to identify changes in MRSA detection rates, and decision analysis was used to compare the costs of detection by PCR and by culture.

Setting.

A 1,200-bed, tertiary care hospital in Canada.

Patients.

Admitted patients at high risk for MRSA colonization. MRSA detection using culture-based screening was compared with a commercial PCR assay.

Results.

The mean monthly incidence of nosocomial MRSA colonization or infection was 0.37 cases per 1,000 patient-days. The time-series model indicated an insignificant decrease of 0.14 cases per 1,000 patient-days per month (95% confidence interval, —0.18 to 0.46) after the introduction of PCR detection (P= .39). The mean interval from a reported positive result until contact precautions were initiated decreased from 3.8 to 1.6 days (P<.001). However, the cost of MRSA control increased from Can$605,034 to Can$771,609. Of 290 PCR-positive patients, 120 (41.4%) were placed under contact precautions unnecessarily because of low specificity of the PCR assay used in the study; these patients contributed 37% of the increased cost. The modeling study predicted that the cost per patient would be higher with detection by PCR (Can$96) than by culture (Can$67).

Conclusion.

Detection of MRSA by the PCR assay evaluated in this study was more costly than detection by culture for reducing MRSA transmission in our hospital. The cost benefit of screening by PCR varies according to incidences of MRSA colonization and infection, the predictive values of the assay used, and rates of compliance with infection control measures.

Hand Hygiene Noncompliance and the Cost of Hospital-Acquired Methicillin-Resistant Staphylococcus aureus Infection

Background.

Hand hygiene noncompliance is a major cause of nosocomial infection. Nosocomial infection cost data exist, but the effect of hand hygiene noncompliance is unknown.

Objective.

To estimate methicillin-resistant Staphylococcus aureus (MRSA)-related cost of an incident of hand hygiene noncompliance by a healthcare worker during patient care.

Design.

Two models were created to simulate sequential patient contacts by a hand hygiene-noncompliant healthcare worker. Model 1 involved encounters with patients of unknown MRSA status. Model 2 involved an encounter with an MRSA-colonized patient followed by an encounter with a patient of unknown MRSA status. The probability of new MRSA infection for the second patient was calculated using published data. A simulation of 1 million noncompliant events was performed. Total costs of resulting infections were aggregated and amortized over all events.

Setting.

Duke University Medical Center, a 750-bed tertiary medical center in Durham, North Carolina.

Results.

Model 1 was associated with 42 MRSA infections (infection rate, 0.0042%). Mean infection cost was $47,092 (95% confidence interval [CI], $26,040–$68,146); mean cost per noncompliant event was $1.98 (95% CI, $0.91–$3.04). Model 2 was associated with 980 MRSA infections (0.098%). Mean infection cost was $53,598 (95% CI, $50,098–$57,097); mean cost per noncompliant event was $52.53 (95% CI, $47.73–$57.32). A 200-bed hospital incurs $1,779,283 in annual MRSA infection-related expenses attributable to hand hygiene noncompliance. A 1.0% increase in hand hygiene compliance resulted in annual savings of $39,650 to a 200-bed hospital.

Conclusions.

Hand hygiene noncompliance is associated with significant attributable hospital costs. Minimal improvements in compliance lead to substantial savings.

Comparison of Mortality Risk Associated With Bacteremia Due to Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus

Objective.

To quantify the clinical impact of methicillin-resistance in Staphylococcus aureus causing infection complicated by bacteremia in adult patients, while controlling for the severity of patients' underlying illnesses.

Design.

Retrospective cohort study from October 1, 1995, through December 31, 2003.

Patients and Setting.

A total of 438 patients with S. aureus infection complicated by bacteremia from a single Veterans Affairs healthcare system.

Results.

We found that 193 (44%) of the 438 patients had methicillin-resistant S. aureus (MRSA) infection and 114 (26%) died of causes attributable to S. aureus infection within 90 days after the infection was identified. Patients with MRSA infection had a higher mortality risk, compared with patients with methicillin-susceptible S. aureus (MSSA) infections (relative risk, 1.7 [95% confidence interval, 1.3-2.4]; P < .01), except for patients with pneumonia (relative risk, 0.7 [95% confidence interval, 0.4-1.3]). Patients with MRSA infections were significantly older (P < .01), had more underlying diseases (P = .02), and were more likely to have severe sepsis in response to their infection (P < .01) compared with patients with MSSA bacteremia. Patients who died within 90 days after S. aureus infection was identified were significantly older (P < .01) and more likely to have severe sepsis (P < .01) and pneumonia (P = .01), compared with patients who survived. After adjusting for age as a confounder, comorbidities, and pneumonia as an effect modifier, S. aureus infection-related mortality remained significantly higher in patients with MRSA infection than in those with MSSA infection, among those without pneumonia (hazard ratio, 1.8 [95% confidence interval, 1.2-3.0]); P < .01.

Conclusions.

The results of this study suggest that patients with MRSA infections other than pneumonia have a higher mortality risk than patients with MSSA infections other than pneumonia, independent of the severity of patients' underlying illnesses.

Nasal screening for MRSA: different swabs--different results!

OBJECTIVES

Swab-based nasal screening is commonly used to identify asymptomatic carriage of Staphylococcus aureus in patients. Bacterial detection depends on the uptake and release capacities of the swabs and on the swabbing technique itself. This study investigates the performance of different swab-types in nasal MRSA-screening by utilizing a unique artificial nose model to provide realistic and standardized screening conditions.

METHODS

An anatomically correct artificial nose model was inoculated with a numerically defined mixture of MRSA and Staphylococcus epidermidis bacteria at quantities of 4×10(2) and 8×10(2) colony forming units (CFU), respectively. Five swab-types were tested following a strict protocol. Bacterial recovery was measured for direct plating and after elution into Amies medium by standard viable count techniques.

RESULTS

Mean recovered bacteria quantities varied between 209 and 0 CFU for MRSA, and 365 and 0 CFU for S. epidermidis, resulting swab-type-dependent MRSA-screening-sensitivities ranged between 0 and 100%. Swabs with nylon flocked tips or cellular foam tips performed significantly better compared to conventional rayon swabs referring to the recovered bacterial yield (p<0.001). Best results were obtained by using a flocked swab in combination with Amies preservation medium. Within the range of the utilized bacterial concentrations, recovery ratios for the particular swab-types were independent of the bacterial species.

CONCLUSIONS

This study combines a realistic model of a human nose with standardized laboratory conditions to analyze swab-performance in MRSA-screening situations. Therefore, influences by inter-individual anatomical differences as well as diverse colonization densities in patients could be excluded. Recovery rates vary significantly between different swab-types. The choice of the swab has a great impact on the laboratory result. In fact, the swab-type contributes significantly to true positive or false negative detection of nasal MRSA carriage. These findings should be considered when screening a patient.

A bundled approach to reduce methicillin-resistant Staphylococcus aureus infections in a system of community hospitals

Methicillin-resistant Staphylococcus aureus (MRSA) infections pose a significant challenge to U.S. healthcare facilities, but there has been limited study of initiatives to reduce infection and increase patient safety in community hospitals. To address this need, a multifaceted program for MRSA infection prevention was developed for implementation in 159 acute care facilities. This program featured five distinct tools-active MRSA surveillance of high-risk patients, enhanced barrier precautions, compulsive hand hygiene, disinfection and cleaning, and executive champions and patient empowerment-and was implemented during 1Q-2Q 2007. Postintervention (3Q 2007-2Q 2008), 10.2% of patients with high-risk for infection or complications due to MRSA had nasal colonization. Volume of disposable gown and alcohol-based hand sanitizer use increased substantially following program implementation. Self-reported rates, based on NHSN definitions, of healthcare-associated central line-associated bloodstream infections and ventilator-associated pneumonia due to MRSA decreased 39% (p < .001) and 54% (p < .001), respectively. Infection rates continued to decrease during the follow-up period (1Q-4Q 2009). This sustained improvement demonstrates that reducing healthcare-associated MRSA infections in a large number of diverse facilities is possible and that a "bundled" approach that translates science into clinical and executive performance expectations may aid in overcoming traditional barriers to implementation.

Management of healthcare-associated methicillin-resistantStaphylococcus aureus

Healthcare-associated methicillin-resistant Staphylococcus aureus is a major cause of nosocomial infections worldwide, with significant attributable morbidity and mortality in addition to pronounced healthcare costs. Treatment results with vancomycin--the current recommended antibiotic for serious methicillin-resistant S. aureus infections--have not been impressive. The recent availability of effective antimicrobial agents other than glycopeptides, such as linezolid and daptomycin, as well as the anticipated approval of newer agents with diverse mechanisms of action, has somewhat ameliorated the threat posed by this organism. However, these drugs are expensive, and there is still no overall satisfactory strategy for reducing the incidence of healthcare-associated methicillin-resistant S. aureus in endemic regions. Although early results with the Society for Healthcare Epidemiology of America guidelines give cause for cautious optimism, long-term experience is lacking, and it is likely that these guidelines will have to be adapted according to local conditions and resources before implementation. Trends to keep in mind when considering the problem of healthcare-associated methicillin-resistant S. aureus include the advent of community-associated methicillin-resistant S. aureus, and the propensity of S. aureus to evolve and acquire resistance determinants over time. This was last vividly demonstrated by the handful of vancomycin-resistant S. aureus isolated recently, which had acquired the vancomycin resistance gene from vancomycin-resistant enterococci.

Impact of antimicrobial multidrug resistance on inpatient care cost: an evaluation of the evidence

This article evaluates the in-hospital costs attributable to antimicrobial multidrug resistance, defined as the difference in averaged costs of the patients infected with a multidrug-resistant (MDR) versus a non-MDR organism. PubMed and Scopus databases were searched to identify relevant studies. Twenty four studies were included: four on carbapenem-resistant or MDR Gram negative nonfermenters, eight on extended-spectrum b-lactamase-producing Enterobacteriaceae and 12 on methicillin-resistant Staphylococcus aureus. In two studies on carbapenem-resistant nonfermenters, the attributable mean hospital charges were US$58,457 and 85,299, respectively. The attributable mean total costs were US$4484 in a study referring to MDR Acinetobacter baumannii, while that varied from US$1584 to 30,093 among studies on extended-spectrum b-lactamase-producing Enterobacteriaceae. With respect to methicillin-resistant S. aureus, the attributable mean total costs varied from US$1014 to 40,090. The in-hospital costs attributable to multidrug resistance are alarmingly high, justifying the application of strict infection control measures in medical institutions with increased rate of MDR infections.