Clinical and Economic Analysis of Methicillin-Susceptible and -Resistant Staphylococcus aureus Infections

Improving Pharmacists’ Awareness of Inadequate Antibiotic Use for URTIs through an Educational Intervention: A Pilot Study

The inadequate use of antibiotics led to the development of multi-resistant bacteria that are now causing millions of deaths worldwide. Since most antibiotics are prescribed/dispensed to treat respiratory tract infections, it is important to raise awareness among health professionals to optimize antibiotic use, especially within the primary care context. Thus, this pilot study aimed to evaluate pharmacists’ feedback about the eHealthResp platform, composed by an online course and a mobile application (app) to help in the management of upper respiratory tract infections (URTIs). Ten community pharmacists were invited to participate in this study, exploring the contents of the eHealthResp platforms and answering a content validation questionnaire composed by eight qualitative and thirty-five quantitative questions about the online course and mobile app. The eHealthResp platform is a comprehensive, consistent, and high-quality e-learning tool. Median scores of 5.00 were attributed to the course contents’ and clinical cases’ adequacy and correction. Most qualitative feedback was about completeness and objectivity of the course, and its usefulness for clinical practice. This study showed that eHealthResp has great potential as an e-health tool for the management of URTIs’ symptoms, which may ultimately aid in reducing inappropriate antibiotic use.

Nanocomposite of Ag nanoparticles and deep eutectic solvent-derived carbon dots with oxidase mimicking activity as synergistic bactericidal agent

A new type of nitrogen and chloride co-doped carbon dots (N/Cl-CDs) based on choline chloride-urea-glycine ternary deep eutectic solvents (DESs) was synthesized using a one-step hydrothermal method. The prepared N/Cl-CDs exhibited oxidase-like activity and excellent antibacterial activity against Escherichia coli, Staphylococcus aureus, and methicillin-resistant staphylococcus aureus (MRSA). The addition of silver nanoparticles (Ag NPs) (i.e., N/Cl-CDs + Ag NPs) to the N/Cl-CDs also significantly enhanced the oxidase and antibacterial activity. The nanocomposite (1.8 mg ml^-1 ) completely inactivated 10⁵ CFU ml^-1 of MRSA in 90 min. E. coli and S. aureus were labeled with the N/Cl-CDs, enabling multicolor fluorescence imaging at different excitation wavelengths. The nanocomposites have high antibacterial efficiency as a new bactericidal agent, as well as application potential with good biocompatibility and low toxicity.

Septic Arthritis Among Users of Injection Drugs: Clinical Course and Microbial Characteristics

Injection drug use (IDU) is a risk factor for septic arthritis (SA) of native joints. Amid the opioid crisis, IDU rates have increased. This study assessed differences in pre-operative characteristics, microbial characteristics, and postoperative outcomes of 177 cases of SA treated operatively from 2015 to 2019 at 3 US hospitals, by self-reported IDU status. Forty cases (23%) involved patients who reported IDU. Patient characteristics, comorbidities, microbial characteristics, duration of hospital stay, discharge destination, follow-up rates, and rates of persistent/secondary infection were compared by self-reported IDU status. Compared with non-IDU-associated SA (non-IDU-SA), IDU-associated SA (IDU-SA) was associated with female sex (P=.001), younger age (P<.001), lower body mass index (P<.001), tobacco use (P<.001), and psychiatric diagnosis (P=.04) and was more likely to involve methicillin-resistant Staphylococcus aureus (P<.001). The IDU-SA was associated with discharge to a skilled nursing facility or against medical advice (P<.001) and with loss to follow-up (P=.01). The 2 groups did not differ in terms of American Society of Anesthesiologists classification, joint involved, Gram stain positivity, presence of bacteremia, peripherally inserted central catheter placement, return to hospital within 3 months, or persistent/secondary positive results on culture within 3 months. Patients with IDU-SA were younger, were more likely to be female, had lower body mass index, and had fewer medical comorbidities but were more likely to use tobacco and to have a psychiatric diagnosis compared with patients with non-IDU-SA. Methicillin-resistant S aureus was more common in the IDU-SA group, as was discharge to a skilled nursing facility or against medical advice. Patients with IDU-SA were less likely to return for follow-up than patients with non-IDU-SA. [Orthopedics. 2021;44(6):e747-e752.].

The Cost-effectiveness of Cefazolin Compared With Antistaphylococcal Penicillins for the Treatment of Methicillin-Sensitive Staphylococcus aureus Bacteremia

Background

Methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia is associated with significant morbidity, mortality, and hospitalization costs. Cefazolin and antistaphylococcal penicillins (ASPs), such as nafcillin, are the preferred treatments for MSSA bacteremia. The aim of this study was to compare the cost-effectiveness of each approach.

Methods

We constructed a decision-analytic model comparing the use of cefazolin with ASPs for the treatment of MSSA bacteremia. Cost-effectiveness was determined by calculating deaths averted and incremental cost-effectiveness ratios (ICERs). Uncertainty was addressed by plotting cost-effectiveness planes and acceptability curves for various willingness-to-pay thresholds.

Results

In the base-case analysis, the cost associated with the cefazolin strategy was $38 863.1, and the associated probability of survival was 0.91. For the ASP strategy, the cost was $48 578.8, and the probability of survival was 0.81. The incremental difference in cost between the 2 strategies was $9715.7, with hospital length of stay being the main driver of cost, and the incremental difference in effectiveness was 0.10. Overall, cefazolin results in savings of $97 156.8 per death averted (ICER, $–97 156.8/death averted). In the probabilistic analysis, at a willingness-to-pay of $50 000, cefazolin had a 68% chance of being cost-effective compared with ASPs. In cost-effectiveness acceptability curves, the cefazolin strategy was cost-effective in 73.5%–81.8% of simulations compared with ASP for a willingness-to-pay ranging up to $50 000.

Conclusions

The use of cefazolin is a cost-effective strategy for the treatment of MSSA bacteremia and, when clinically appropriate, this strategy results in considerable health care cost-savings.

T Cell Immunity and the Quest for Protective Vaccines against Staphylococcus aureus Infection

Staphylococcus aureus is a wide-spread human pathogen, and one of the top causative agents of nosocomial infections. The prevalence of antibiotic-resistant S. aureus strains, which are associated with higher mortality and morbidity rates than antibiotic-susceptible strains, is increasing around the world. Vaccination would be an effective preventive measure against S. aureus infection, but to date, every vaccine developed has failed in clinical trials, despite inducing robust antibody responses. These results suggest that induction of humoral immunity does not suffice to confer protection against the infection. Evidence from studies in murine models and in patients with immune defects support a role of T cell-mediated immunity in protective responses against S. aureus. Here, we review the current understanding of the mechanisms underlying adaptive immunity to S. aureus infections and discuss these findings in light of the recent S. aureus vaccine trial failures. We make the case for the need to develop anti-S. aureus vaccines that can specifically elicit robust and durable protective memory T cell subsets.

Baicalin protects mice from infection with methicillin-resistant Staphylococcus aureus via alleviating inflammatory response

Sepsis was redefined as life-threatening organ dysfunction caused by a dysregulated host response to infection in 2016. One of its most common causes is Staphylococcus aureus, especially methicillin-resistant Staphylococcus aureus (MRSA), which leads to a significant increase in morbidity and mortality. Therefore, innovative and effective approaches to combat MRSA infection are urgently needed. Recently, host-directed therapy (HDT) has become a new strategy in the treatment of infectious diseases, especially those caused by antibiotic-resistant bacteria. Baicalin (BAI) is the predominant flavonoid and bioactive compound isolated from the roots of Radix Scutellariae (Huang Qin), a kind of traditional Chinese medicine. It has been reported that BAI exhibits multiple biological properties such as anti-oxidant, antitumor, and anti-inflammatory activities. However, the therapeutic role of BAI in MRSA infection is still unknown. In this study, it is found that BAI treatment inhibited the production of IL-6, TNF-α, and other cytokines from MRSA- or bacterial mimics-stimulated Mϕs and dendritic cells (DCs). BAI played an anti-inflammatory role by inhibiting the activation of ERK, JNK MAPK, and NF-κB pathways. Moreover, the serum level of TNF-α was decreased, whereas IL-10 was increased, in mice injected with MRSA. Furthermore, the bacterial load in livers and kidneys were further decreased by the combination of BAI and vancomycin (VAN), which might account for the amelioration of tissue damage. BAI reduced the high mortality rate caused by MRSA infection. Collectively, the results suggested that BAI may be a viable candidate of HDT strategy against severe sepsis caused by antibiotic-resistant bacteria such as MRSA.

Click-to-Capture: A method for enriching viable Staphylococcus aureus using bio-orthogonal labeling of surface proteins

Staphylococcus aureus is one of the principal causative agents of bacteremia which can progress to sepsis. Rapid diagnostic tests for identification and antibiotic resistance profiling of S. aureus would improve patient outcomes and antibiotic stewardship, but existing methods require a lengthy culture step to obtain enough material for testing. Complexity of the host matrix, where pathogenic microbes are often present, also interferes with many diagnostic methods. Here, we describe a straightforward and rapid method for enriching viable S. aureus using bio-orthogonal, or “click,” chemistry methods. Bacteria labeled in this manner can potentially be cultured, interrogated using molecular methods for pathogen identification, or used to test antibiotic susceptibility.

A novel trehalosamine isolated from Bacillus amyloliquefaciens and its antibacterial activities

Bacillus amyloliquefaciens has been widely used as a probiotic in the field of biological control,and its antibacterial compounds plays an important role in the prevention and control of plant, livestock and poultry diseases. It has the advantages of green, safe and efficiency. This study aims to separate and purify active ingredient from Bacillus amyloliquefaciens GN59 and study its antibacterial activity. A novel compound was isolated from GN59 by column chromatography on silica gel and HPLC purification. The chemical structure was identified as α-D-glucopyranosyl-(1 → 1')-3'-amino-3'-deoxy-β-D-glucopyranoside (a,β-3-trehalosamine) on the basis of spectroscopic analysis. This is the first report about a,β-3-trehalosamine isolated from biological resources on an antibiotic activity against pathogenic bacterium. The 3'-neotrehalosamine displayed antibacterial activity across a broad spectrum of microorganisms, including different gram-positive and gram-negative bacteria, with minimal inhibitory concentration (MIC) values ranging from 0.5 to 0.7 mg/mL. The results indicated that the 3'-neotrehalosamine from GN59 might be a potential candidate for bactericide.

Impact of multi-drug resistant bacteria on economic and clinical outcomes of healthcare-associated infections in adults: Systematic review and meta-analysis

Background

Infections with multidrug resistant (MDR) bacteria in hospital settings have substantial implications in terms of clinical and economic outcomes. However, due to clinical and methodological heterogeneity, estimates about the attributable economic and clinical effects of healthcare-associated infections (HAI) due to MDR microorganisms (MDR HAI) remain unclear. The objective was to review and synthesize the evidence on the impact of MDR HAI in adults on hospital costs, length of stay, and mortality at discharge.

Methods and findings

Literature searches were conducted in PubMed/MEDLINE, and Google Scholar databases to select studies that evaluated the impact of MDR HAI on economic and clinical outcomes. Eligible studies were conducted in adults, in order to ensure homogeneity of populations, used propensity score matched cohorts or included explicit confounding control, and had confirmed antibiotic susceptibility testing. Risk of bias was evaluated, and effects were measured with ratios of means (ROM) for cost and length of stay, and risk ratios (RR) for mortality. A systematic search was performed on 14^th March 2019, re-run on the 10^th of June 2019 and extended the 3^rd of September 2019. Small effect sizes were assessed by examination of funnel plots. Sixteen articles (6,122 patients with MDR HAI and 8,326 patients with non-MDR HAI) were included in the systematic review of which 12 articles assessed cost, 19 articles length of stay, and 14 mortality. Compared to susceptible infections, MDR HAI were associated with increased cost (ROM 1.33, 95%CI [1.15; 1.54]), prolonged length of stay (ROM 1.27, 95%CI [1.18; 1.37]), and excess in-hospital mortality (RR 1.61, 95%CI [1.36; 1.90]) in the random effects models. Risk of publication bias was only found to be significant for mortality, and overall study quality good.

Conclusions

MDR HAI appears to be strongly associated with increases in direct cost, prolonged length of stay and increased mortality. However, further comprehensive studies in this setting are warranted.

Trial registration

PROSPERO (CRD42019126288).

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.

A Payer Perspective of the Hospital Inpatient Additional Care Costs of Antimicrobial Resistance in France: A Matched Case-Control Study

BACKGROUND AND OBJECTIVE

Antimicrobial resistance (AMR) has become one of the biggest threats to global public health given its association with mortality, morbidity and cost of health care. However, little is known on the economic burden of hospitalization attributable to AMR from a public health insurance perspective. We assessed the excess costs to the French public health insurance system attributable to AMR infections in hospitals.

METHODS

Bacterial infectious disease-related hospitalizations were extracted from the National health data information system for all stays occurring in 2015. Bacterial infections, strains, and microbial resistance were identified by specific French ICD-10 codes. Information about health care expenditure, co-morbidities and demographic characteristics (i.e. gender, age) are provided. We used a matched case-control approach to determine the excess of reimbursements paid to stays with AMR compared to stays with an infection without resistance. Cases and controls were matched on gender, age, Charlson comorbidity index, category of infection, infection as principal diagnosis (two classes), microorganism and hospital status. The overall AMR cost was extrapolated to stays with AMR and excluded from the sample (multiple infections), and a second extrapolation was performed to consider stays with unknown resistance status.

RESULTS

The final sample included 52,921 matched-pairs (98.2% cases). Our results suggest that AMR overall cost reached EUR109.3 million in France with a mean of EUR1103 per stay; extrapolation to the entire database shows that the overall cost could potentially reach EUR287.1 million if all cases would be identified. The mean excess length of hospital stay attributable to AMR was estimated at 1.6 days.

CONCLUSION

AMR causes substantial cost burden in France for the public health insurance. Our study confirms the need to reinforce programs to prevent AMR infection and thereby reduce their economic burden.

Electronic Nose in the Detection of Wound Infection Bacteria from Bacterial Cultures: A Proof-of-Principle Study

BACKGROUND

Soft tissue infections, including postoperative wound infections, result in a significant burden for modern society. Rapid diagnosis of wound infections is based on bacterial stains, cultures, and polymerase chain reaction assays, and the results are available earliest after several hours, but more often not until days after. Therefore, antibiotic treatment is often administered empirically without a specific diagnosis.

METHODS

We employed our electronic nose (eNose) system for this proof-of-concept study, aiming to differentiate the most relevant bacteria causing wound infections utilizing a set of clinical bacterial cultures on identical blood culture dishes, and established bacterial lines from the gaseous headspace.

RESULTS

Our eNose system was capable of differentiating both methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa, and Clostridium perfringens with an accuracy of 78% within minutes without prior sample preparation. Most importantly, the system was capable of differentiating MRSA from MSSA with a sensitivity of 83%, a specificity of 100%, and an overall accuracy of 91%.

CONCLUSIONS

Our results support the concept of rapid detection of the most relevant bacteria causing wound infections and ultimately differentiating MRSA from MSSA utilizing gaseous headspace sampling with an eNose.

Poorly Cross-Linked Peptidoglycan in MRSA Due to mecA Induction Activates the Inflammasome and Exacerbates Immunopathology

Methicillin-resistant S. aureus (MRSA) is a leading health problem. Compared to methicillin-sensitive S. aureus, MRSA infections are associated with greater morbidity and mortality, but the mechanisms underlying MRSA pathogenicity are unclear. Here we show that the protein conferring β-lactam antibiotic resistance, penicillin-binding protein 2A (encoded by the mecA gene), directly contributes to pathogenicity during MRSA infection. MecA induction leads to a reduction in peptidoglycan cross-linking that allows for enhanced degradation and detection by phagocytes, resulting in robust IL-1β production. Peptidoglycan isolated from β-lactam-challenged MRSA strongly induces the NLRP3 inflammasome in macrophages, but these effects are lost upon peptidoglycan solubilization. Mutant MRSA bacteria with naturally occurring reduced peptidoglycan cross-links induce high IL-1β levels in vitro and cause increased pathology in vivo. β-lactam treatment of MRSA skin infection exacerbates immunopathology, which is IL-1 dependent. Thus, antibiotic-induced expression of mecA during MRSA skin infection contributes to immunopathology by altering peptidoglycan structure.

Efficacy of ampicillin against methicillin-resistant Staphylococcus aureus restored through synergy with branched poly(ethylenimine)

Beta-lactam antibiotics kill Staphylococcus aureus bacteria by inhibiting the function of cell-wall penicillin binding proteins (PBPs) 1 and 3. However, β-lactams are ineffective against PBP2a, used by methicillin-resistant Staphylococcus aureus (MRSA) to perform essential cell wall crosslinking functions. PBP2a requires teichoic acid to properly locate and orient the enzyme, and thus MRSA is susceptible to antibiotics that prevent teichoic acid synthesis in the bacterial cytoplasm. As an alternative, we have used branched poly(ethylenimine), BPEI, to target teichoic acid in the bacterial cell wall. The result is restoration of MRSA susceptibility to the β-lactam antibiotic ampicillin with a MIC of 1 μg/mL, superior to that of vancomycin (MIC = 3.7 μg/mL). A checkerboard assay shows synergy of BPEI and ampicillin. Nuclear magnetic resonance (NMR) data show that BPEI alters the teichoic acid chemical environment. Laser scanning confocal microscopy (LSCM) images show BPEI residing on the bacterial cell wall where teichoic acids and PBPs are located.

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.

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).

Healthcare Costs Associated with Hemodialysis Catheter–Related Infections: A Single-Center Experience

In patients undergoing hemodialysis, catheter-related bacteremia results in expensive hospitalizations. In our study, the mean cost was $23,451 per hospitalization. When itemized, housing (“bed-related”) costs accounted for 66% of the total; laboratory costs accounted for 4%, radiologic costs accounted for 9%, and procedure-related costs accounted for 21%. Hypoalbuminemia and bacteremia due to methicillin-resistant Staphylococcus aureus (MRSA) are associated with higher healthcare costs; bacteremia due to MRSA is also associated with poor survival rates.

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.

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 comparison of long-term outcomes after meticillin-resistant and meticillin-sensitive Staphylococcus aureus bacteraemia: an observational cohort study

BACKGROUND

Findings from previous studies have suggested that outcomes after meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia are worse than after meticillin-sensitive S. aureus (MSSA) bacteraemia. We assessed whether patients who had MRSA bacteraemia had a higher risk of death and recurrent infections than those who had MSSA bacteraemia.

METHODS

For this observational cohort study, we assessed data from the microbiology laboratory database at the Royal Perth Hospital (WA, Australia). Data were for all patients who had an episode of MRSA bacteraemia between July 1, 1997, and June 30, 2007, and, by use of a computer-generated randomisation sequence, a randomly selected subgroup of patients who had an episode of MSSA bacteraemia (patients with one or more set of blood cultures positive for S. aureus). The primary outcomes were survival time and subsequent infection-related hospital readmissions, analysed by Cox proportional hazards regression with adjustment for important prognostic factors.

FINDINGS

Of the 583 patients who had an episode of MRSA or MSSA bacteraemia, we used data for the 582 who had complete data linkage: 185 patients who had MRSA bacteraemia and 397 patients who had MSSA bacteraemia. The crude survival time of patients after MRSA bacteraemia was shorter than it was for patients with MSSA bacteraemia (14 months [IQR 1-86] vs 54 months [3-105]; hazard ratio 1·46, 95% CI 1·18-1·79; p=0·01). The adverse association between MRSA and all-cause mortality (0·98, 0·77-1·30; p=0·87) or infection-related mortality (1·22, 0·89-1·69; p=0·22) were not statistically significant after adjustment for important prognostic factors including age, comorbidities, severity of acute illness, metastatic infections, and long-term care facility resident status. After adjustment for these confounding factors, we saw no difference in infection-related hospital readmissions between patients who had MRSA bacteraemia and those who had MSSA bacteraemia (odds ratio 0·95, 95% CI 0·59-1·53; p=0·83).

INTERPRETATION

Long-term outcomes after MRSA bacteraemia were worse than those after MSSA bacteraemia through its confounding associations with other prognostic factors. Our findings might have implications for management strategies to control MRSA colonisation.

FUNDING

The Medical Research Foundation of Royal Perth Hospital.

Large retrospective evaluation of the effectiveness and safety of ceftaroline fosamil therapy

Ceftaroline has been approved for acute bacterial skin infections and community-acquired bacterial pneumonia. Limited clinical experience exists for use outside these indications. The objective of this study was to describe the outcomes of patients treated with ceftaroline for various infections. Retrospective analyses of patients receiving ceftaroline ≥72 h from 2011 to 2013 were included. Clinical and microbiological outcomes were analyzed. Clinical success was defined as resolution of all signs and symptoms of infection with no further need for escalation while on ceftaroline treatment during hospitalization. A total of 527 patients received ceftaroline, and 67% were treated for off-label indications. Twenty-eight percent (148/527) of patients had bacteremia. Most patients (80%) were initiated on ceftaroline after receipt of another antimicrobial, with 48% citing disease progression as a reason for switching. The median duration of ceftaroline treatment was 6 days, with an interquartile range of 4 to 9 days. A total of 327 (62%) patients were culture positive, and the most prevalent pathogen was Staphylococcus aureus, with a frequency of 83% (271/327). Of these patients, 88.9% (241/271) were infected with methicillin-resistant S. aureus (MRSA). Clinically, 88% (426/484) achieved clinical success and hospital mortality was seen in 8% (40/527). While on ceftaroline, adverse events were experienced in 8% (41/527) of the patients and 9% (28/307) were readmitted within 30 days after discharge for the same infection. Patients treated with ceftaroline for both FDA-approved and off-label infections had favorable outcomes. Further research is necessary to further describe the role of ceftaroline in a variety of infections and its impact on patient outcomes.

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.

Antimicrobial Efficacy of Gatifloxacin and Moxifloxacin with and without Benzalkonium Chloride Compared with Ciprofloxacin and Levofloxacin Against Methicillin- ResistantStaphylococcus aureus

We compared the antimicrobial activity of gatifloxacin and moxifloxacin with and without benzalkonium chloride (BAK) against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). Minimum inhibitory concentrations (MICs) against clinical isolates of MRSA were evaluated. Approximately 10(5 )CFU/ml of methicillinresistant S. aureus was added to Mueller-Hinton broth containing two-fold concentration increments of drug. For the evaluation of gatifloxacin with BAK, 50 microg/ml of BAK were added to the first well of the plate with gatifloxacin or moxifloxacin and then serially diluted. The combination of gatifloxacin or moxifloxacin with BAK was more active than either fluoroquinolone without BAK. The MICs ranged from <or=0.008 microg/ml to 0.125 microg/ml for gatifloxacin plus BAK, from 0.063 microg/ml to (3)8 microg/ml with unpreserved gatifloxacin from <0.004 to 0.25 for moxifloxacin plus BAK, and from <or=0.016 microg/ml to 16.0 microg/ml with unpreserved moxifloxacin. The combinations of gatifloxacin or moxifloxacin and BAK were highly active against MRSA in vitro, providing MICs that were approximately 2- to 500-fold lower than the MICs provided by either gatifloxacin or moxifloxacin without BAK.

Clinical Outcomes in Patients with Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Bloodstream Infection

The prevalence of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) infections varies in the literature, a problem complicated by the lack of routine screening procedures; however, limited data suggest that hVISA has been associated with persistent bloodstream infections (BSI) and vancomycin failure, yet these studies have been confounded by design issues. We conducted this study to compare the characteristics of patients with BSI caused by hVISA with those with vancomycin-susceptible Staphylococcus aureus (VSSA) treated with vancomycin. This retrospective, multicenter matched (1:1) cohort study compared the clinical characteristics and outcomes of hVISA and VSSA. Patients with hVISA methicillin-resistant Staphylococcus aureus (MRSA) BSI from 2004 to 2012 were matched to VSSA-MRSA BSI patients. The primary outcome was failure of vancomycin treatment, defined as a composite of persistent bacteremia (≥7 days), persistent signs and symptoms, change of MRSA antibiotic, recurrent BSI, or MRSA-related mortality. We identified 122 matched cases. The overall vancomycin failure rate was 57% (82% hVISA versus 33% VSSA; P < 0.001). The individual components of failure in hVISA versus VSSA were persistent bacteremia, 59% versus 21% (P < 0.001); change in MRSA therapy, 54% versus 25% (P = 0.001); MRSA-related mortality, 21% versus 10% (P = 0.081); and recurrence of BSI, 26% versus 2% (P < 0.001). Using logistic regression analysis and adjusting for covariates, hVISA (adjusted odds ratio [aOR], 11.1; 95% confidence interval [CI], 4.3 to 28.7) and intensive care unit (ICU) admission (aOR, 4.5; 95% CI, 1.8 to 11.6) were still independently associated with vancomycin failure. Relative to VSSA BSI, patients with hVISA were more likely to experience failure of vancomycin treatment, including persistent bacteremia and recurrence. Our results indicate that hVISA was responsible for considerable morbidity.

Artesunate has its enhancement on antibacterial activity of β-lactams via increasing the antibiotic accumulation within methicillin-resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) has now emerged as a predominant and serious pathogen because of its resistance to a large group of antibiotics, leading to high morbidity and mortality. Therefore, to develop new agents against resistance is urgently required. Previously, artesunate (AS) was found to enhance the antibacterial effect of β-lactams against MRSA. In this study, AS was first found to increase the accumulation of antibiotics (daunorubicin and oxacillin) within MRSA by laser confocal microscopy and liquid chromatography-tandem MS method, suggesting the increased antibiotics accumulation might be related to the enhancement of AS on antibiotics. Furthermore, AS was found not to destroy the cell structure of MRSA by transmission electron microscope. AS was found to inhibit gene expressions of important efflux pumps such as NorA, NorB and NorC, but not MepA, SepA and MdeA. In conclusion, our results showed that AS was capable of enhancing the antibacterial activity of β-lactams via increasing antibiotic accumulations within MRSA through inhibiting gene expressions of efflux pumps such as NorA, NorB and NorC, but did not destroy the cell structure of MRSA. AS could be further investigated as a candidate drug for treatment of MRSA infection.

Dose-ranging study to assess the application of intranasal 2% mupirocin calcium ointment to eradicate Staphylococcus aureus nasal colonization

BACKGROUND

Mupirocin nasal ointment may be prescribed for decolonization prior to surgical procedures, especially for carriers of methicillin-resistant Staphylococcus aureus (MRSA). The approved regimen for decolonization of S. aureus from the anterior nares is twice daily for 5 d (10 doses). We performed a two-center, randomized, open-label study to compare the utility of six and 10 doses for decolonization of S. aureus.

METHODS

Patients expecting to undergo surgery were screened for S. aureus nasal carriage approximately three weeks prior to the procedure. Those found to be positive were offered enrollment in the study. In the first arm (n=41), patients were randomized to receive 2, 3, or 5 d (six or 10 doses) of treatment prior to their operation. Their anterior nares were swabbed for culture and S. aureus polymerase chain reaction (PCR) during the decolonization therapy period as well as for four weeks after surgery. In the second arm (n=60), all patients were given 5 d (10 doses) of nasal mupirocin treatment, and the patient's anterior nares were swabbed for culture and S. aureus PCR for four weeks after surgery. Data from six of the patients were excluded from analysis because of failure to submit swabs after operation. All S. aureus isolates were tested for susceptibility to mupirocin and the presence of the mecA gene to detect MRSA.

RESULTS

In Arm 1, 16 patients received 10 doses of mupirocin, 18 received six doses (twice daily for 3 d), and 7 received six doses (thrice daily for 2 d). In the second arm, all patients received 10 doses of mupirocin (twice a day for 5 d). Overall, 89.5% patients who received 10 doses of mupirocin remained decolonized for at least four weeks after surgery versus 68.0% of patients who received six doses (p=0.016). There was no difference between arms 1 and 2 for those given mupirocin twice daily for 5 d.

CONCLUSION

The ten-dose regimen is superior to any six-dose regimen for de-colonizing S. aureus from the anterior nares of patients and for maintaining the decolonized state for at least four weeks after therapy.

COMMUNITY ACQUIRED METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS HAND INFECTIONS: A SOUTH PACIFIC PERSPECTIVE — CHARACTERISTICS AND IMPLICATIONS FOR ANTIBIOTIC COVERAGE

Purpose: Community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) infections are reported to be increasing worldwide. In the United States when rates exceed 15% empiric treatment is suggested. The aim of our study was to determine local rates and treatment of CA-MRSA within our region.

Methods: Nine hundred and forty-two patients were admitted to our service during a six-year period with culture-positive hand infections identified from operative cultures at the time of surgery.

Results: Sixty-six (7.0%) patients had CA-MRSA positive cultures identified. Thirty-two (48.5%) patients were noted to have remained on antibiotic treatment that did not reflect their MRSA positive status after cultures returned. Despite this, re-admission and re-operation rates were low and comparable to our non-MRSA control group.

Conclusions: Within our CA-MRSA group, current rates do not support automatic empiric treatment for CA-MRSA. Based on sensitivity data, co-trimoxazole and intravenous vancomycin are appropriate and effective antibiotic treatment within our region. Our data supports the importance of drainage of pyogenic infections in helping to resolve complicated hand infections.

Methicillin-resistant Staphylococcus aureus bloodstream infection: risk factors and clinical outcome in non-intensive-care units

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is spread out in hospitals across different regions of the world and is regarded as the major agent of nosocomial infections, causing infections such as skin and soft tissue pneumonia and sepsis. The aim of this study was to identify risk factors for methicillin-resistance in Staphylococcus aureus bloodstream infection (BSI) and the predictive factors for death.

METHODS

A retrospective cohort of fifty-one patients presenting bacteraemia due to S. aureus between September 2006 and September 2008 was analysed. Staphylococcu aureus samples were obtained from blood cultures performed by clinical hospital microbiology laboratory from the Uberlândia Federal University. Methicillinresistance was determined by growth on oxacillin screen agar and antimicrobial susceptibility by means of the disk diffusion method.

RESULTS

We found similar numbers of MRSA (56.8%) and methicillin-susceptible Staphylococcus aureus (MSSA) (43.2%) infections, and the overall hospital mortality ratio was 47%, predominantly in MRSA group (70.8% vs. 29.2%) (p=0.05). Age (p=0.02) was significantly higher in MRSA patients as also was the use of central venous catheter (p=0.02). The use of two or more antimicrobial agents (p=0.03) and the length of hospital stay prior to bacteraemia superior to seven days (p=0.006) were associated with mortality. High odds ratio value was observed in cardiopathy as comorbidity.

CONCLUSIONS

Despite several risk factors associated with MRSA and MSSA infection, the use of two or more antimicrobial agents was the unique independent variable associated with mortality.

Implications of stress-induced genetic variation for minimizing multidrug resistance in bacteria

BACKGROUND

Antibiotic resistance in bacterial infections is a growing threat to public health. Recent evidence shows that when exposed to stressful conditions, some bacteria perform higher rates of horizontal gene transfer and mutation, and thus acquire antibiotic resistance more rapidly.

METHODS

We incorporate this new notion into a mathematical model for the emergence of antibiotic multi-resistance in a hospital setting.

RESULTS

We show that when stress has a considerable effect on genetic variation, the emergence of antibiotic resistance is dramatically affected. A strategy in which patients receive a combination of antibiotics (combining) is expected to facilitate the emergence of multi-resistant bacteria when genetic variation is stress-induced. The preference between a strategy in which one of two effective drugs is assigned randomly to each patient (mixing), and a strategy where only one drug is administered for a specific period of time (cycling) is determined by the resistance acquisition mechanisms. We discuss several features of the mechanisms by which stress affects variation and predict the conditions for success of different antibiotic treatment strategies.

CONCLUSIONS

These findings should encourage research on the mechanisms of stress-induced genetic variation and establish the importance of incorporating data about these mechanisms when considering antibiotic treatment strategies.

Detection and analysis of Staphylococcus aureus isolates found in ambulances in the Chicago metropolitan area

BACKGROUND

Given the frequency with which many different strains of Staphylococcus aureus are found in various prehospital settings, this study sought to characterize S aureus isolates taken from one such environment. The objectives were to determine the frequency of S aureus in front-line, advanced life support (ALS) ambulances throughout the Chicago metropolitan area, and to generate antibiograms (antibiotic resistance profiles) for each S aureus isolate using 8 clinically relevant antibiotics.

METHODS

Samples were obtained from 26 sites in 71 ambulances from 34 different Chicago-area municipalities. Selected colonies that demonstrated a growth pattern consistent with that of S aureus were subjected to a latex agglutination test specific for S aureus. Antibiograms and genetic analyses were performed on all latex agglutination test-positive isolates.

RESULTS

At least one S aureus isolate was found in approximately 69% of all ambulances in the study. Of all isolates detected, 77% showed resistance to at least one antibiotic, and 34% displayed resistance to 2 or more antibiotics. Some level of oxacillin resistance was found in 21% of isolates; however, only slightly more than half of these oxacillin-resistant isolates were found to carry the methicillin-resistant S aureus-specific SCCmec cassette. Some 12% of all isolates were ultimately determined to be methicillin-resistant S aureus, whereas the remaining 88% were methicillin-sensitive S aureus with varying antibiograms.

CONCLUSIONS

Antibiotic resistance appears to be prevalent in S aureus isolates detected in Chicago area ALS ambulances. Given the ease with which S aureus can survive on inanimate surfaces and exchange antibiotic resistance elements, a conscientious approach to the application of existing cleaning techniques, especially in key ambulance sites, is needed. Future work will include further characterizing isolates using multiple techniques, as well as follow-up studies with interested municipalities.

HIC@RE … and its relevance for a company like RIEMSER

The increased incidence of infections caused by methicillin-resistant strains of Staphylococcus aureus (MRSA) burdens the healthcare systems with significant additional costs. Simple measures such as active MRSA screening can lead to a reduction of infectious events and massive savings. To establish an effective and comprehensive strategy for prevention and eradication of MRSA, the cooperation and networking of all stakeholders in the health care system is necessary. Pharmaceutical companies are part of the health care system; they therefore have a vital and ethical interest that care within the health system will be further optimized and thus continue to remain affordable. The targets of the HIC@RE project demonstrate the interests of the pharmaceutical and health-care research company RIEMSER Arzneimittel AG, so that a sufficient rationale is given for cooperation in this project.

Pre-emptive contact precautions for intubated patients reduced healthcare-associated meticillin-resistant Staphylococcus aureus transmission and infection in an intensive care unit

Healthcare-associated infection by meticillin-resistant Staphylococcus aureus (MRSA) is still a great concern in an intensive care unit (ICU). Our surveillance data in the ICU revealed that intubated patients were at eight times higher risk of acquiring MRSA than non-intubated patients, so we hypothesised that pre-emptive contact precautions for all intubated patients would prevent healthcare-associated infection by MRSA in the ICU. Patients staying in our ICU for >2 days were included in this study. The study period was divided into two periods. During 2004 (1st period), contact precautions were performed only for patients with MRSA. During 2005–2007 (2nd period), contact precautions were applied to all intubated patients regardless of MRSA infection status. Patients were defined as MRSA-positive on admission when MRSA was detected by surveillance or clinical culture on enrolment. Other MRSA-positive results were defined as healthcare-associated MRSA (HA-MRSA) transmission. HA-MRSA infection was diagnosed according to the National Nosocomial Infections Surveillance Manual. The 1st period comprised 415 patients, and the 2nd period comprised 1280 patients. In intubated patients, HA-MRSA infection rate decreased significantly in the 2nd period (1st period 12.2%, 2nd period 5.6%; P = 0.015). HA-MRSA infection of all patients decreased from 3.6 to 2.3 incidents per 1000 patient-days (P < 0.05), despite a significant increase in the rate of patients MRSA positive on admission in the 2nd period (1st period 2.9%; 2nd period 6.1%). Pre-emptive contact precautions for intubated patients would be helpful in reducing HA-MRSA infection in ICU.

Methicillin-resistant Staphylococcus aureus: the superbug

Over the last decade, methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged as serious pathogens in the nosocomial and community setting. Hospitalization costs associated with MRSA infections are substantially greater than those associated with methicillin-sensitive S. aureus (MSSA) infections, and MRSA has wider economic effects that involve indirect costs to the patient and to society. In addition, there is some evidence suggesting that MRSA infections increase morbidity and the risk of mortality. Glycopeptides are the backbone antibiotics for the treatment of MRSA infections. However, several recent reports have highlighted the limitations of vancomycin, and its role in the management of serious infections is now being reconsidered. Several new antimicrobials demonstrate in vitro activity against MRSA and other Gram-positive bacteria. Data from large surveys indicate that linezolid, daptomycin, and tigecycline are almost universally active against MRSA. This review will briefly discuss the epidemiology, costs, outcome, and therapeutic options for the management of MRSA infections.

Community-acquired Staphylococcus aureus pneumonia among hospitalized children in Hawaii

SUMMARY BACKGROUND

Invasive community acquired (CA) Staphylococcus aureus (SA) disease has been endemically observed in Hawaiian children. We wanted to evaluate the clinical, laboratory findings, and outcomes of methicillin-resistant SA (MRSA) and methicillin-susceptible SA (MSSA) associated pneumonia admissions.

METHODS

We performed retrospective chart reviews of 38 culture proven SA pneumonia patients admitted to a pediatric tertiary medical center in Hawaii between January 1996 to December 2007.

RESULTS

Twenty-six patients (68%) had MRSA and 12 patients (32%) had MSSA infection. The mean age of MRSA patients was 2.8 and 6.7 years for MSSA patients (P < 0.05). Pacific Islander and Native Hawaiian patients were affected disproportionately compared to non-Pacific Islander and Hawaiian groups (P < 0.0001). Demographic data, days of fever, tachypnea, hypoxia, and length of stay (LOS) were not significantly different between MRSA and MSSA infected patients. The mean LOS was 26.2 days (range 6-138 days); mean length of fever was 12.4 days. Seventy five percent (15 of 20) of patients who required intubation had MRSA. Twenty-one of the 29 (72%) total patients with pleural effusions had MRSA infection and all required chest tube placements. Two (5%) patients died; both had MRSA infection.

CONCLUSIONS

Younger Pacific Islander/Native Hawaiian children were affected disproportionately and had MRSA infection more frequently. MRSA infected patients appeared to have severe disease with frequent chest tube placement, intubation, and fatality. Overall, both MRSA and MSSA pneumonia resulted in prolonged hospitalization, multiple complications, and significant healthcare costs.

Factors associated with variation in estimates of the cost of resistant infections

BACKGROUND

Existing estimates of the costs of antimicrobial resistance exhibit broad variability, and the contributing factors are not well understood. This study examines factors that contribute to variation in these estimates.

METHODS

Studies of the costs of resistant infections (1995-2009) were identified, abstracted, and stated in comparable terms (eg, converted to 2007 U.S. dollars). Linear regressions were conducted to assess how costs incurred by patients with resistant infections versus those incurred by uninfected or susceptible-organism-infected controls varied according to (1) costs incurred by control subjects; (2) study population characteristics; (3) methodological factors (eg, matching); and (4) length of stay.

RESULTS

Estimates of difference in costs incurred by patients with resistant infections versus patients without resistant infections varied between $-27,609 (control costs exceeded case costs) and $126,856. Differences were greater when the costs incurred by control subjects were higher (ie, when the underlying cost of care was high). Study-adjusted cost differences were greater for bloodstream infections (vs. any other infection site), for studies that reported median (vs. mean) costs, for studies that reported total (vs. postinfection or infection-associated) costs, for studies that used uninfected (vs. susceptible-organism-infected) controls, and for studies that did not match or adjust for length of stay before infection.

CONCLUSION

The cost of antimicrobial resistance seems to vary with the underlying cost of care. Increased costs of resistance are partially explained by longer length of stay for patients with resistant infections. Further research is needed to assess whether interventions should be differentially targeted at the highest cost cases.

Periprosthetic joint infection: the economic impact of methicillin-resistant infections

The orthopedic community has begun to witness a worrisome rise in the incidence of periprosthetic joint infections (PJIs) caused by resistant organisms. Besides other challenges associated with treating these infections, it appears that these infections may pose a higher cost compared to infections caused by sensitive organisms. Significantly higher cost of care for treatment of infections due to methicillin-resistant organisms were seen at a mean of $107,264 per case compared to $68,053 for treating PJI caused by sensitive strains (P < .0001). More effective strategies for preventing the spread of infections caused by resistant organisms need to be implemented to ease the social and economic strains facing the orthopedic community due to resistant organisms.

The role of beta-hemolytic streptococci in causing diffuse, nonculturable cellulitis: a prospective investigation

Staphylococcus aureus and beta-hemolytic streptococci (BHS) are the 2 main types of bacteria causing soft-tissue infections. Historically, BHS were believed to be the primary cause of diffuse, nonculturable cellulitis. However, with the recent epidemic of community-associated methicillin-resistant S aureus (MRSA) causing culturable soft-tissue infections, it is currently unclear what role either of these bacteria has in cases where the cellulitis is diffuse and nonculturable. This uncertainty has led to broad-spectrum and haphazard use of antibiotics for this infection type, which has led to increased risk of adverse drug reactions, health care costs, and emergence of resistance in bacteria. To investigate this issue, we conducted a prospective investigation between December 2004 and June 2007, enrolling all adult patients admitted to the inpatient service at the Olive View-UCLA Medical Center, a county hospital of Los Angeles, with diffuse, nonculturable cellulitis. Acute and convalescent serologies for anti-streptolysin-O and anti-DNase-B antibodies were obtained. Patient data were analyzed for response to beta-lactam antibiotics. The primary outcome was the proportion of these cases caused by BHS, as diagnosed by serologies and/or blood cultures, and the secondary outcome was the response rate of patients to beta-lactam antibiotics. Of 248 patients enrolled, 69 were dropped from analysis because of loss to follow-up or exclusion criteria. Of the 179 remaining patients, 73% of nonculturable cellulitis cases were caused by BHS. Analysis of outcomes to beta-lactam antibiotic treatment revealed that patients diagnosed with BHS had a 97% (71/73) response, while those who did not have BHS had a 91% (21/23) response, with an overall response rate of 95.8% (116/121). Results of this large, prospective study show that diffuse, nonculturable cellulitis is still mainly caused by BHS, despite the MRSA epidemic, and that for this infection type, treatment with beta-lactam antibiotics is still effective. A cost-effective, evidence-based algorithm can be useful for the empiric management of uncomplicated soft-tissue infections based on the presence or absence of a culturable source.

Management of methicillin-resistant Staphylococcus aureus pneumonia

PURPOSE OF REVIEW

Staphylococcus aureus, and particularly methicillin-resistant Staphylococcus aureus (MRSA) has become an increasingly important etiology of pneumonia, both in healthcare and community settings. Associated with highest morbidity, mortality and costs in public health, it represents a major challenge for the management of this group of patients.

RECENT FINDINGS

MRSA is one of the most common pathogens of ventilator associated pneumonia, whereas its estimated incidence for hospital acquired pneumonia, healthcare associated pneumonia and community acquired pneumonia has risen in the past decades. Although vancomycin at standard doses remains as the mainstay for its treatment, the increasing rate of treatment failure has prompted other strategies of use (more frequent administration, continuous infusion, combination therapy), and the use of newer antimicrobials, particularly linezolid, with pharmacokinetic and pharmacodynamic profiles which produce promisingly improved clinical results.

SUMMARY

Overall, MRSA is an important cause of pneumonia; optimal management strategies for improving morbidity and mortality are still under development.

Staphylococcus aureus osteomyelitis in Hawaii

BACKGROUND

The clinical and laboratory findings and outcomes of methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) Staphylococcus aureus osteomyelitis have not been studied in Hawaii.

METHODS

Retrospective inpatient chart reviews of 62 culture-proven osteomyelitis patients between 1996 and 2007 were performed.

RESULTS

Fifteen patients (24%) had MRSA infection, and 47 patients (76%) had MSSA infection. Length of stay, chronic health problems, total duration of fever, and length of treatment were not significantly different between MRSA- and MSSA-infected patients. The peak erythrocyte sedimentation rate and C-reactive protein values were higher among MRSA infected patients (P values: .009 and .003, respectively).The systemic complication rate was higher in MRSA-infected patients (P value: .018).

CONCLUSIONS

Differing from other pediatric staphylococcal infections in Hawaii, the majority of the patients had MSSA infection. Pacific Islander and Native Hawaiian ethnicities were affected disproportionately and had MRSA infection more frequently. MRSA-infected patients had frequent surgical procedures and systemic complications.