MRSA Group Research Articles

Effective screening methods to prevent surgical site infections in orthopedic surgery: an observational study

BackgroundThe bacterial source of surgical-site infections (SSIs) can have either endogenous and/or exogenous origins, and some studies have revealed that endogenous transmission is an important pathway for SSIs in orthopedic surgery. However, since the frequency of SSIs is low (0.5–4.7%), screening all surgery patients is labor-intensive and cost-prohibitive. The goal of this study was to better understand how to improve the efficacy of nasal culture screening in preventing SSIs.MethodsNasal cultures for 1616 operative patients over a 3-year period were evaluated for the presence of nasal bacterial microbiota and the species identity. We also investigated the medical factors that influence colonization and evaluated the ratio of agreement between nasal cultures and SSI-causing bacteria.ResultsIn a survey of 1616 surgical cases, 1395 (86%) were normal microbiota (NM), 190 (12%) were MSSA carriers, and 31 (2%) were MRSA carriers. The risk factors for MRSA carriers were significantly higher than the NM group in patients with a history of hospitalization (13 [41.9%], p = 0.015), patients who had been admitted to a nursing facility (4 [12.9%], p = 0.005), and patients who were > 75 years of age (19 [61.3%], p = 0.021). The incidence of SSIs was significantly higher in the MSSA group (17/190 [8.4%]) than the NM group (10/1395 [0.7%], p = 0.00). The incidence of SSIs in the MRSA group (1/31 [3.2%]) tended to be higher than that in the NM group, but there was no statistically significant difference (p = 0.114). The concordance rate between causative bacteria of SSI and species present in nasal cultures was 53% (13/25 cases).ConclusionsThe results of our study suggest screening patients with a history of past hospitalization, a history of admission in a long-term care facility, and older than 75 to reduce SSIs.Trial registrationThis study was approved by the institutional review board of the authors’ affiliated institutions (the ethics committee of Sanmu Medical Center, 2016-02).

Impact of combined versus single-mode training programs based on drop jump and specific multidirectional repeated sprint on bio-motor ability adaptations: a parallel study design in professional basketball players

BackgroundJumping and specific multidirectional repeated sprint ability are important in basketball. The objective of this study was to assess the contributions of 8-week combined versus single-mode training programs based on drop jump (DJ) and specific multidirectional repeated sprint (MRSA) on repeated sprint ability performances, body balance and lower limbs power in male professional basketball players.MethodsThis study followed a randomized parallel study design. Fifty-two professional male basketball players from the Tunisian first division participated in this study. The players were randomly assigned to 4 groups: DJ group (JG; n = 13), MRSA group (RSG; n = 13), combined group (COMB; n = 13) and an active control group (CON; n = 13). The JG, RSG and COMB groups completed the 8-week training programs with 2 sessions per week while the CON continues their regular basketball training. Training volume was similar between groups all over the experimental period. Before and after the intervention, the four groups were evaluated for the stork test, Y-balance test, the repeated sprint ability test (IRSA5COD), the squat jump (SJ) and countermovement jump (CMJ) tests, the single leg drop jump test, the five time-jump test and T—change of direction (CoD) test.ResultsAll measures displayed significant main effect, (medium/small) magnitude (effect size) improvements for time (post-test > pre-test) except the physiological parameters for IRSA5COD. Significant time × group interactions were revealed for body balance, T test, IRSA5COD (total time and best time) and jump tests (vertical/horizontal). Bonferroni corrected post-hoc tests revealed significant greater improvement in favor of RSG and COMB compared to JG for body balance, CoD and IRSA5COD. Moreover, greater improvement in CMJ, SJ and single leg DJ in favor of JG compared to the RSG. In addition, a greater CoD improvement was observed in favor of COMB when compared to the RSG.ConclusionCombined and single-mode training programs based on DJ and MRSA contributed to a significantly better performance in specific basketball physical fitness parameters with results favoring combined interventions.

LB12. Exebacase Shows Rapid Symptom Resolution in a Phase 2 Study in Adult Patients with Staphylococcus aureus bacteremia

BackgroundExebacase (EXB), a recombinantly-produced lysin (cell wall hydrolase), is the first direct lytic agent to advance into Phase 3 of clinical development for the treatment of bacteremia including infective endocarditis due to Staphylococcus aureus. The microbiologic attributes of EXB, including pathogen-targeted rapid bacteriolysis, and biofilm eradication are distinct from and synergistic with those of traditional antibiotics and underpin the therapeutic potential for EXB.MethodsThe Phase 2 trial was a randomized, double-blind, placebo-controlled multinational study. Patients were randomized (2:1) to receive a single 2-hour infusion of EXB or placebo (PBO) in addition to standard of care antibiotics. Time to resolution of symptoms (shortness of breath, sweating, fatigue and confusion) attributable to the bacteremia was analyzed using Kaplan-Meier methods. Time to resolution was defined as the number of days until all attributable symptoms were absent. If a new (not present at baseline) attributable symptom was present before the baseline symptoms resolved, this new symptom also had to be absent for symptoms to be considered resolved.ResultsA total of 86 patients (53 EXB and 33 PBO) had at least one attributable symptom present at baseline. Of these, symptoms resolved in 94.3% and 87.9% of EXB and PBO patients, respectively. The median time to resolution was 3 days for EXB and 6 days for PBO patients. Median days to symptom resolution in the MRSA group was 3 and 7 days for EXB and PBO patients, respectively, and 3 and 5 days for EXB and PBO patients in the MSSA group, respectively. Time to symptom resolution in MRSA patients in presented in Figure 1.Figure 1. Time to Resolution of Symptoms in Patients with MRSA Bacteremia including Infective Endocarditis ConclusionThe majority of EXB and PBO patients had symptom resolution. However, EXE patients achieved symptom resolution in 3 days compared with 6 days for PBO patients overall, and 7 days for PBO patients with MRSA. These data suggest that rapid bacteriolysis may translate to a clinical benefit for patients receiving EXB and aligns with a median length of hospital stay of 6 and 10 days among US MRSA patients that received EXE and PBO patients, respectively. (Fowler, et al, 2020).Disclosures Cara Cassino, MD, ContraFect Corporation (Employee) Anita F. Das, PhD, Adagio (Consultant)AN2 (Consultant)Cidara (Consultant)ContraFect (Consultant)Iterum (Consultant)MicuRx (Consultant)Paratek (Consultant)Union (Consultant) Joy Lipka, MS, ContraFect Corporation (Consultant)

Outcomes of Pediatric Patients With Sepsis Related to Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus Infections Requiring Extracorporeal Life Support: An ELSO Database Study.

Background: Extracorporeal membrane oxygenation (ECMO) is increasingly utilized for pediatric sepsis unresponsive to steroids and inotropic support. Outcomes of children with sepsis are influenced by the type of pathogen causing their illness.Objective: To determine if the outcomes of children with Staphylococcus aureus sepsis receiving ECMO differed according to microbial sensitivity (Methicillin-resistant Staphylococcus aureus [MRSA] vs. Methicillin-sensitive Staphylococcus aureus [MSSA]).Methods: Retrospective case-matched cohort study of children (0–<18 years) with Staphylococcus aureus sepsis reported to the ELSO registry from more than 995 centers. Inclusion criteria were age 0–18 years, laboratory diagnosis of Staphylococcal infection, clinical diagnosis of sepsis, and ECMO deployment. Exclusion criteria were no laboratory diagnosis of Staphylococcal infection. We compared patient demographics, pre-ECMO management and outcomes of those with MRSA vs. MSSA using Chi-Square test, with independent samples t-test used to test to compare continuous variables.Results: In our study cohort of 308 patients, 160 (52%) had MSSA and 148 (48%) MRSA with an overall survival rate of 41.5%. There were no differences in the age group (p = 0.76), gender distribution (p = 0.1) or racial distribution (p = 0.58) between the two groups. P value for racial distribution should be 0.058. There were 91 (56.8%) deaths in the MSSA group and 89 (60.1%) deaths (p = 0.56) in the MRSA group. Duration on ECMO (p = 0.085) and the time from intubation to ECMO (p = 0.37) were also similar in the two groups. Survival with MSSA sepsis and MRSA sepsis did not improve significantly over the 20 years evaluated despite an increase in ECMO utilization.Conclusion: In this multi-center retrospective study, there were no differences in outcomes for children receiving ECMO support with Staphylococcus aureus sepsis according to microbial methicillin sensitivity. There was no significant increase in survival among patients with MRSA and MSSA infections receiving ECMO in the last 20 years.

Length of stay, hospitalisation costs and in-hospital mortality of methicillin-susceptible and methicillin-resistant Staphylococcus aureus bacteremia in Japan

ObjectivesTo examine the length of stay, hospitalisation costs and case fatality of methicillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA) bacteremia in Japan. Study designRetrospective cohort study. Patients with a diagnosis of S. aureus bacteremia who were admitted to a tertiary care hospital (the National Centre for Global Health and Medicine [NCGM]) in Tokyo, Japan, between 1st January 2016 and 31st December 2020 were included in the study. MethodsWe combined Japan Nosocomial Infections Surveillance data and Diagnosis Procedure Combination data at NCGM from 2016 to 2020. The data were stratified into MSSA and MRSA groups. Length of stay (LoS), LoS after submission of a blood culture specimen (LoS-after), hospitalisation cost, hospitalisation costs per day and clinical outcome were compared after propensity score matching. ResultsMedian LoS was 46 (interquartile range [IQR] 28.5–64.5) days in the MSSA group and 66 (IQR 40–91) days in the MRSA group (P = 0.020). Median LoS-after was 38 (IQR 25–62.5) days and 45 (IQR 24–63) days (P = 0.691) in the MSSA and MRSA groups, respectively. Median hospitalisation cost was significantly higher in the MRSA group (26,035 [IQR 18,154–47,362] USD) than in the MSSA group (19,823 [IQR 13,764–32,042] USD) (P = 0.036), but cost per day was not (MRSA: 528.9 [IQR 374.9–647.4] USD; MSSA: 455.6 [IQR 359.2–701.7] USD; P = 0.990). Case fatality rate was higher in the MRSA group than in the MSSA group (22/60 vs 9/60, P = 0.012). ConclusionsPatients with MRSA bacteremia had longer LoS and higher costs than those with MSSA bacteremia. However, LoS-after and hospitalisation costs per day were not different. The longer LoS of patients in Japan compared with other countries might contribute to the higher disease burden of S. aureus bacteremia in Japan.

Community-Acquired Methicillin-Resistant Staphylococcus aureus Infections in Acutely Ill Children: A Retrospective Case-Control Study.

To test if admission clinical and laboratory variables could reliably discriminate community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections from methicillin-sensitive Staphylococcus aureus (MSSA) infections in acutely ill children, and to describe the epidemiology, clinical features and outcomes among children with Staphylococcal infections admitted to the hospital. The authors conducted this retrospective case-control study comparing children with CA-MRSA and MSSA infections admitted to hospital between June 2014 and June 2017. They describe the evolving epidemiology and attempt to identify clinical and laboratory variables that can differentiate MRSA cases from MSSA controls. They used multivariate logistic regression to identify independent predictors of MRSA infection and Cox-proportional hazard analysis to compare survival times. Seventy-three children were enrolled, of which 35 had CA-MRSA and 38 had MSSA infections. Children in MRSA group were younger [median (IQR) age in months: 36 (12, 62) vs. 56 (37, 96); p = 0.032]. MRSA and MSSA groups had similar rate of skin and soft tissue involvement (SSTI) [62.9% vs. 54.1%; p = 0.449]. Median duration of illness was lower in MRSA, 6 vs. 8.5 d (p = 0.001). TLC of 8100 or less was 82% sensitive and 94% specific for MRSA sepsis at admission [AUROC = 0.64 (0.51-0.77), p = 0.04]. Mortality (8.6% vs. 10.5% p = 1.0) and length of ICU stay (7.2 vs. 9.3 d, p = 0.24) were similar in both. None of the admission variables were predictive of MRSA culture-positivity on regression analysis. The hospital-based incidence of CA-MRSA infections among children appears to be increasing. None of the admission clinical or laboratory variables could reliably identify CA-MRSA infections. As there seems to be no reliable way to differentiate children with MSSA and MRSA infections, physicians may consider empiric initiation of broad-spectrum antibiotics at admission to cover both MSSA and MRSA, especially in critically ill children with suspected Staphylococcal infections.

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) spa type t127, Sequence Type (ST)1, quickly spreads and persists among young pigs.

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) clones other than Clonal Complex (CC)398, as CC1, have been isolated in pigs in some countries, and appeared to be prevalent in Italy. The aim of this study was to evaluate the capability of Sequence Type (ST)1, CC1, LA-MRSA clone to colonize and to be transmitted among piglets. Eighteen caesarean-derived/colostrum-deprived piglets of 35 days of age were assigned randomly to three groups: four seeder piglets were contaminated with a spa type t127, ST1, SCCmec V, MRSA (Group A), 10 MRSA-negative piglets were exposed to Group A after 2 days post-contamination, dpc (Group B) and 4 piglets were used as control group (Group C). Piglets were evaluated until 44 dpc (Group A) or at 42 days post-exposure, dpe (Group B) and then euthanized and necropsied. All nasal and skin cultures of Group A resulted MRSA-positive throughout the experiment starting from two dpc, while Group C tested always MRSA-negative. At first sampling, all Group B piglets became positive and remained positive throughout the experiment. This is the first colonization/transmission study with a CC1 LA-MRSA in pigs. The results add further knowledge on the ability of CC1 LA-MRSA to colonize pigs, and on colonization/transmission patterns, both suggesting good host adaptation.

Necrotizing Fasciitis and Methicillin Resistant Staphylococcus Aureus

Necrotizing fasciitis (NF) is an aggressive and life-threatening infection of skin and soft tissue characterized by widespread fascial necrosis which leads to morbidity and mortality if left untreated. There is difficulty in managing this condition because there is a combination of difficulty in diagnosis, and also of early as well as late management. It can be caused by either a single organism or more frequently by a variety of microbes - both aerobic and anaerobic. Necrotizing fasciitis seems to have preponderance in males, perhaps due to increased incidence of trauma in males. Staphylococcus aureus is the most prevalent pathogen in hospitals and communities and MRSA has become a common isolate associated with skin and soft tissue infections over the past few years, monomicrobial MRSA necrotizing fasciitis has been reported only in a few studies. Early surgical intervention, early diagnosis and aggressive treatment should be done. Material and Methods: All patients were diagnosed as NF on surgical report. Surgical exploration is undertaken after resuscitation. Penicillin along with, an amino glycoside and clindamycin or metronidazole is administered preoperatively in moribund patients. Cefoxitin or imipenem or meropenem is used in more limited infections. Fair amount of desloughing is done without anesthesia. Overlying fat as patchy greenish-black liquefaction necrotic tissues are excised primarily, and specimen sent for culture in microbiology department. Cultures were processed the susceptibility of S. aureus isolates to antimicrobials was done. Results: A total of 200 hospitalized patients those who were surgically treated for NF were included in the study. Of the 200 patients 42 patients were culture positive for MRSA. In our study mean age was 56± 11.21 of which 124 (62%) were male , mean hospitalization days were 16.5± 6.2. patients with underlying diabetes mellitus were 66 (33%) and hypertension were 74(37%). In MRSA group (n=42) mean age was 53 ± 9.22. Male were 36 (73.81%) , mean hospitalization days were 17.6 ± 6.2. patients with underlying diabetes mellitus were 21 (50%) and hypertension were 19(45.24%).42 (21%) were MRSA, 31 (15.5%) were MSSA, 21 (10.5%) were coagulase negative staphylococcus, 4(2%) were Streptococcus group A, 11 (5.5%) were Streptococcus species, 6 (3%) were Bacillus species, 24 (12 %) were Escherichia coli, 19 (9.5%) were Acinetobacter species, 3 (1.5%) were Candida albicans and in 30 (15%) no growth was observed in culture. Discussion and Conclusion: Some experts recommend use of broad-spectrum empirical antimicrobial therapy for suspected cases of necrotizing fasciitis and therapy directed against MRSA is not a standard practice. For treatment selection of appropriate antimicrobial agents for any suspected necrotizing fasciitis must take into account the nature of patient's exposure and local epidemiologic data but no reliable epidemiological or clinical risk factors with MRSA from those infected with MSSA or non-S. aureus are available. In our study mean age of patients diagnosed NF was 53 ± 9.22. While male were 36 (73.81%). In study by Cheng NC et al. the median age was 62 years (range, 12-81 years) There was male predominance in NF by MRSA in our study . In our study lesions on extremities had better prognosis similar results were shown in other study. Necrotizing fasciitis caused by MRSA is a challenge to the treating surgeon. Prompt diagnosis and surgical management with empiric MRSA cover in areas where community acquired MRSA (CA-MRSA) is endemic. Lesions of extremities have better prognosis where MRSA infection is becoming endemic and empirical treatment of suspected necrotizing fasciitis or pneumonia should include active MRSA cover.

The efficacy of platelet-rich plasma gel in MRSA-related surgical wound infection treatment: an experimental study in an animal model.

The wound healing properties of platelet-rich plasma (PRP) gel have been documented in many studies. PRP gel has also become a promising agent for treating surgical site infections. In this study, we investigated the antibacterial activity and wound healing effectiveness of PRP in an animal model of Methicillin-resistant Staphylococcus aureus subsp. aureus (MRSA N315)-contaminated superficial soft tissue wounds. Subcutaneous wounds in Wistar Albino male rats were created by making two cm midline incisions followed by inoculation of microorganisms. Study groups comprised of Sham (no treatment), PRP alone, MRSA alone, MRSA + PRP, MRSA + Vancomycin, and MRSA + Vancomycin + PRP groups. We inoculated 0.1mL (3 × 108 CFU/mL) of MRSA in contaminated groups. After 8 days, all rats were killed, wounds were excised and subjected to histopathologic examination, and MRSA counts were determined. MRSA counts in MRSA, MRSA + PRP, MRSA + Vancomycin and MRSA + Vancomycin + PRP groups were 5.1 × 106 (SD ± 0.4) CFU/mL, 4.3 × 106 (SD ± 0.7) CFU/mL, 2.3 × 106 (SD ± 0.3) CFU/mL, 1.1 × 106 (SD ± 0.4) CFU/mL, respectively. The inflammation scores of MRSA + PRP, MRSA + Vancomycin, and MRSA + Vancomycin + PRP groups were significantly lower than the MRSA group. MRSA + Vancomycin + PRP group inflammation score was significantly lower than the MRSA + PRP group. All treatment groups were effective in wound healing and decreasing the MRSA counts. MRSA + PRP combined created identical inflammation scores to the PRP group. More in vivo studies are required to corroborate these findings.

Antibiotic Sensitivity in Post Cesarean Surgical Site Infection at a Tertiary Care Centre in Eastern Nepal

Introduction: Post cesarean surgical site infection (SSI) is one of the common complications diagnosed in 2.5%-16% of the cases and is associated with significant increase in maternal morbidity, hospital stay, costs, and psychological stress to the new parents. This study was designed to study the incidence of SSI and the antimicrobial resistance pattern in our hospital.&#x0D; &#x0D; Methods: This was a prospective observational study conducted from July 2015 to December 2015, in which all patients who were admitted with post cesarean SSI or developed SSI during their stay were included. Wound specimens were collected and susceptibility testing was carried out using disc diffusion technique.&#x0D; &#x0D; Results: The incidence of post cesarean SSI was 6.07% (47/774). Out of the 47 patients who had SSI, 35 (74.75%) had positive swab culture. The most important organism isolated was Staphylococcus aureus (82.85%) out of which 17 (58.62%) were MRSA strain. The resistance of Staphylococcus to penicillin was 84.6% whereas amikacin was found to be highly sensitive (&gt;96%). Among the MRSA strain, resistance to ciprofloxacin, which is the currently used drug for prophylaxis, was 94%. Resistance to penicillins, cephalosporins, and clavulanate was also high. Resistance to vancomycin was also high (53%). Amikacin and chloramphenicol were found to be highly sensitive (94% and 90% respectively) in the MRSA group.&#x0D; &#x0D; Conclusion: MRSA is the leading cause of post cesarean SSI and is a matter of great concern. Amikacin and chloramphenicol were found to be highly sensitive in this group but unlike other studies, resistance of vancomycin was showing an increasing trend.

Epidemiology, antibiotic consumption and molecular characterisation of Staphylococcus aureus infections--data from the Polish Neonatology Surveillance Network, 2009-2012.

BackgroundOur aim was to determine and characterize S. aureus (SA) isolated from infections in newborns for antibiotic resistance, virulence factors, genotypes, epidemiology and antibiotic consumption.MethodsProspective surveillance of infections was conducted. Data about antibiotic treatment were analyzed. Antimicrobial susceptibility was assessed. PCR amplification was used to detect resistance and virulence genes. Typing methods such as PFGE, spa-typing and SCCmec were used.ResultsSA was found to be associated with 6.5% of infections. Methicillin-Resistant Staphylococcus aureus accounted for 32.8% of SA-infections. An incidence of MRSA-infections was 1.1/1000 newborns. MRSA-infections were diagnosed significantly earlier than MSSA-infections in these newborns (14th day vs. 23rd day (p = 0.0194)). MRSA-infections increased the risk of newborn’s death. Antibiotic consumption in both group was similar, but a high level of glycopeptides-usage for MSSA infections was observed.In the MRSA group, more strains were resistant to erythromycin, clindamycin, gentamicin and amikacin than in the MSSA group. Hla gene was present in 93.9% of strains, and seg and sei in 65.3% of strains, respectively. One dominant clone was found among the 14 MRSA isolates. Fifteen strains belonging to SCCmec type IV were spa-t015 and one strain belonging to SCCmec type V was spa-t011.ConclusionsResults obtained in the study point at specific epidemiological situation in Polish NICU (more detailed studies are recommended).High usage of glycopeptides in the MSSA infections treatment indicates the necessity of antimicrobial stewardship improvement and introducing molecular screening for early identification of infections.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-0890-3) contains supplementary material, which is available to authorized users.

Matched-Cohort DNA Microarray Diversity Analysis of Methicillin Sensitive and Methicillin Resistant Staphylococcus aureus Isolates from Hospital Admission Patients

As genotyping of S. aureus is important for epidemiologic research and for hygiene management, methods are required for standardized fast and easily applicable evaluation of closely related epidemic strains with high prevalence in hospitals. In this single centre matched control study we compared a new commercially available DNA microarray (IdentiBAC) with standard spa-typing for S. aureus genotyping. Included in the study was a subgroup of 46 MRSA and matched 46 MSSA nasal isolates of the Saarland University Medical Center collected during a state-wide admission prevalence screening. Microarray (MA) and also spa-typing could easily differentiate the genetically diverse MSSA group. However, due to the predominance of CC5/t003 in the MRSA group a sufficient subtyping required analysis of more complex genetic profiles as was shown here by the MA comprising a total number of 334 different hybridization probes. The genetic repertoire of the MRSA group was characterized by more virulence genes as compared to the MSSA group. The standard evaluation of MA results by the original software into CCs, agr-, SCCmec- and capsule-types was substituted in the present study by implementation of multivariate subtyping of closely related CC5 isolates using three different bioinformatic methods (splits graph, cluster dendrogram, and principal component analysis). Each method used was applicable for standardized and highly discriminative subtyping with high concordance. We propose that the identified S. aureus subtypes with characteristic virulence gene profiles are presumably associated also with virulence and pathogenicity in vivo; however, this remains to be analyzed in future studies. MA was superior to spa-typing for epidemiologic and presumably also provide functional respectively virulence associated characterization of S. aureus isolates. This is of specific importance for the hospital setting. In future, MA could become a new standard test for S. aureus typing in combination with multivariate bioinformatic analysis.

Drug-Susceptible S. aureus Still Dangerous

Bruce Jancin is with the Denver bureau of Elsevier Global Medical News. VIENNA – Methicillin-resistant Staphylococcus aureus bloodstream infections grab the headlines and are the focus of many infection-prevention directives, but methicillin-susceptible S. aureus infections, which receive far less attention, have comparable morbidity and mortality, according to two European studies. “MSSA bloodstream infection is MRSA's evil twin,” Michael Laum, MD, said at the European Congress of Clinical Microbiology and Infectious Diseases. He compared key outcomes for 52 patients with MSSA bloodstream infection and 16 with MRSA bloodstream infection at Blackpool Victoria Hospital in Lancashire, England, during a 20-month period starting in November 2007. There were far fewer cases of MRSA infection because incidence plunged by 78% in the year after the hospital introduced a comprehensive MRSA containment program. The average length of stay was 23.2 days for patients with MSSA infection and 26.3 days with MRSA. The MSSA patients averaged 61 years of age, the MRSA patients 71. Eighteen percent of MSSA patients were admitted to intensive care, as were 19% with MRSA. In-hospital mortality was 34% in the MSSA patients and 44% in the MRSA group. The average Acute Physiology and Chronic Health Evaluation (APACHE) II score at the time blood cultures were obtained was 13 points in the MSSA group and 16 for the MRSA patients. Eighty-four percent of the MSSA patients had optimal antibiotics initiated before their blood culture results were known, as did just 54% of those with MRSA. Seventy-one percent of MSSA infections and 80% of MRSA infections had their onset less than 48 hours after patient hospitalization, strongly suggesting community-acquired infection. The lesson of the study is mandatory MRSA screening and surveillance program ought to be expanded to incorporate MSSA, concluded Dr. Lau of the hospital's general surgery department. A similar point was made in the Burden of Resistance and Disease in European Nations (BURDEN) study presented by Marlieke de Kraker of the National Institute for Public Health and the Environment, Bilthoven, the Netherlands. BURDEN included all adult patients with MRSA or MSSA bloodstream infection at a tertiary care hospital in each of 13 European countries during a 1-year period. The study population comprised 248 patients with MRSA and 453 controls matched for age, Charlson Comorbidity Index score, and duration of hospital stay before infection, along with 618 patients with MSSA and 1,170 matched controls. Patients with MSSA often present with a different clinical picture than do those with MRSA, Ms. de Kraker said. Patients with MRSA infection tend to be older and have more comorbidities. In-hospital mortality occurred in 36% of the MRSA group and 9% of their controls, and in 23% of the MSSA group and 7% of their controls. In a multivariate analysis, MRSA infection was associated with a 3.5-fold increased risk of in-hospital mortality, and MSSA carried a 3.1-fold increased mortality risk compared with controls. Another multivariate analysis demonstrated that bloodstream infection with MRSA added an average of 9.2 days to the length of a hospital stay, while MSSA resulted in an extra 8.6 days, she reported. “The burden of S. aureus bloodstream infections in the hospital is high, for MRSA as well as MSSA. Methicillin resistance does not seem to be associated with excess length of stay or mortality. Infection prevention should be aimed at decreasing the number of S. aureus bloodstream infections, irrespective of methicillin susceptibility,” Ms. de Kraker said. Dr. Lau and Ms. de Kraker each reported having no financial conflict.

Clinical impact of methicillin resistance on outcome of patients with Staphylococcus aureus infection: A stratified analysis according to underlying diseases and sites of infection in a large prospective cohort

This study was conducted to identify the predictors of mortality and to evaluate the impact of methicillin resistance on outcome in patients with Staphylococcus aureus infection according to underlying conditions and type of infection. An observational cohort study including 4949 patients with S. aureus infection was conducted. We compared data from patients with MRSA infection with those with MSSA infection. The 30-day mortality rate of MRSA group was significantly higher than that of MSSA group (15.6% vs. 6.2%, P < 0.001). However, MRSA infection was not found to be independent risk factor for mortality after adjusting for other variables (OR = 1.03, 95% CI = 0.80-1.32). When we analyzed patients with S. aureus bacteremia (n = 709), MRSA infection was found to be significantly associated with mortality in multivariate analysis (Adjusted OR = 1.69, 95% CI = 1.15-2.49). When the 30-day mortality rates were compared according to underlying diseases, the 30-day mortality rate of MRSA group was significantly higher than that of MSSA group in patients with malignancy or renal diseases. MRSA infection was also found to be one of the independent risk factors for mortality in patients with malignancy (adjusted OR = 1.69, 95% CI = 1.06-2.70) and in those with renal disease (adjusted OR = 1.70, 95% CI = 1.0-2.89), after adjustment for host variables. Methicillin resistance adversely affected the outcome of patients with S. aureus infection, in patients with cancer or renal disease and in those with S. aureus bacteremia, although MRSA infection was not found to be significantly associated with higher mortality in overall patient population.

Adequacy of Antimicrobial Treatment and Outcome ofStaphylococcus aureusBacteremia in 9 Western European Countries

Little is known about the incidence of inadequate treatment of severe Staphylococcus aureus infection in Europe. We aimed to evaluate the adequacy of antibiotic therapy for S. aureus bacteremia (SAB), to identify determinants of inadequate treatment, and to determine the effect of inadequate treatment on patient outcome in a representative selection of hospitals in 9 Western European countries. In this retrospective cohort study, all adult patients with SAB (due to methicillin-susceptible S. aureus [MSSA] or methicillin-resistant S. aureus [MRSA]) who were admitted to 60 randomly selected hospitals from 1 November 2007 through 31 December 2007 were included. Adequate antimicrobial therapy was defined as intravenous administration of at least 1 antibiotic to which the isolate showed in vitro susceptibility that was initiated within 2 days after onset of SAB. A total of 334 SAB episodes (257 due to MSSA and 77 due to MRSA) were included. Ninety-four patients (28%) received inadequate empirical therapy (21% in the MSSA group and 52% in the MRSA group). Both length of stay before SAB onset and methicillin-resistant infection were associated with inadequate therapy, with adjusted odds ratios (ORs) of 1.01 (95% confidence interval [CI], 1.00-1.03) and 3.7 (95% CI, 2.2-6.4), respectively. Age (OR, 1.06; 95% CI, 1.03-1.10), Charlson comorbidity score (OR, 2.1; 95% CI, 1.2-3.6), severe sepsis or septic shock (OR, 2.7; 95% CI, 1.5-4.8), and intensive care unit stay at onset of SAB (OR, 2.9; 95% CI, 1.5-5.6) but not inadequate treatment (OR, 0.7; 95% CI, 0.4-1.3) were associated with increased 30-day mortality. Inadequate empirical antimicrobial therapy for SAB is common in Western Europe and is strongly associated with infection caused by MRSA. In this study, inadequate treatment was not associated with increased 30-day mortality rates.

Molecular Surveillance and Population Structure Analysis of Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus in High-Risk Wards

In this study we report the results of analysis of 253 isolates of Staphylococcus aureus (132 methicillin [meticillin]-resistant S. aureus [MRSA] isolates and 121 methicillin-susceptible S. aureus [MSSA] isolates) from 209 patients admitted to 18 high-risk wards of six hospitals located in Florence, Italy, over an 8-month period during which a program of epidemiological surveillance of hospital-acquired infections was conducted. The majority (69%) of the 87 reported S. aureus infections were caused by MRSA. No outbreak events have been reported. All the isolates were typed by amplified fragment length polymorphism (AFLP), and AFLP profiles were analyzed in order to define similarity groups. The discriminatory power of AFLP is very high with MSSA (Simpson index of diversity [D], 95.9%), whereas its resolution capability with MRSA (D, 44.7%) is hampered by the well-known high clonality of these populations (the main MRSA group accounted for 74% of the MRSA isolates). Combining AFLP, improved by visual inspection of polymorphisms, with multiplex PCR greatly increases MRSA resolution (D, 85.5%), resolving the MRSA population to a level that is one of the highest reported in the literature. Widespread and sporadic clones of MSSA and MRSA were identified, and their diffusion in the different hospitals and wards over the surveillance period was studied. The understanding of MSSA and MRSA population structures should be the starting point for the design of a more rational surveillance program for S. aureus species, maximizing benefits and reducing the cost of infection control strategies.

Differential host response to Methicillin‐resistant Staphylococcus aureus and Pseudomonas aeruginosa

Despite the outstanding achievement in treatment of sepsis, the mortality rate of septic patients is high. The objective of the study was to describe differential host response to different infectious agents using our well‐established ovine sepsis model.MethodSheep were given the injury via tracheostomy under anesthesia. Study groups: 1) sham, (no injury), n=6; 2) Smoke (Smoke inhalation) n=6; 3) PS (smoke inhalation &amp; Ps. aeruginosa (1011CFU) instilled into the lungs, n=6; 4) MRSA (smoke inhalation &amp; MRSA (1011CFU) instilled into the lungs, n=6. After injury, sheep were awakened, maintained on mechanical ventilation, and fluid resuscitated for 24 h.Results:Mean arterial pressure was similarly depleted in MRSA and PS groups. The severity of lung injury was more pronounced in PS group, which was associated with higher expression of lung IL‐1, 6, and 8. MRSA group had 2‐fold higher fluid retention associated with significantly higher nitric oxide (NO) production and vascular endothelial growth factor (VEGF). The lung tissue arginase level and IL‐13 was higher in PS group.Conclusion:Excess IL‐13 leading to higher arginase activity in PS may result in lesser production of NO. The severe vascular leak in MRSA group may be due to excess NO and VEGF. Differential responses to different pathogenic agents require more focused treatment approach considering the nature of infectious agents and specific host response to it

Epidemiology, clinical and laboratory characteristics of Staphylococcus aureus bacteraemia in a university hospital in UK

There has been a persistent increase in the number of meticillin-resistant Staphylococcus aureus (MRSA) and meticillin-susceptible Staphylococcus aureus (MSSA) bacteraemia in the UK. This prospective study included 147 episodes of S. aureus bacteraemia in 139 patients over a 14 month period, from 1 November 2001 to 31 December 2002. Eighty-seven (59%) episodes in 84 patients and 60 (41%) in 56 patients were due to MRSA and MSSA, respectively. An intra-vascular device (29, 33%) and a soft-tissue (15, 25%) source were the commonest identifiable foci for bacteraemia in the MRSA and MSSA groups, respectively. Attributable mortality in the MRSA group was higher than the MSSA group (33% vs 16%; P=0.03) but there was no statistical difference for either attributable (P=0.35) or crude (P=0.39) mortality between the two groups, when adjusted for age, respiratory focus and inappropriate antibiotic therapy. A respiratory source (P=0.02) and inappropriate antibiotic therapy (P=0.02) were associated with attributable mortality in the MRSA group whereas advanced age was the only risk factor (P=0.02) in the MSSA group. The present study shows that S. aureus bacteraemia continues to be a serious infection mostly affecting the elderly and emphasizes the need for improved strategy in the control and management of this condition.

Mupirocin-resistant, methicillin-resistant Staphylococcus aureus: does mupirocin remain effective?

To determine the efficacy of mupirocin ointment in reducing nasal colonization with mupirocin-susceptible, methicillin-resistant Staphylococcus aureus (MS MRSA) as well as mupirocin-resistant MRSA (MR MRSA). Prospective evaluation in which patients colonized with MRSA were treated twice daily with 2% topical mupirocin ointment for 5 days. James H. Quillen Veterans' Affairs Medical Center. Forty hospitalized patients with two anterior nares cultures positive for MRSA within a 7-day period. Treated patients had post-treatment cultures at day 3 and weeks 1, 2, and 4. Isolates underwent mupirocin-susceptibility testing and DNA typing. MRSA clearance and type turnover were assessed for isolates that were mupirocin-susceptible, low-level (LL) MR MRSA and high-level (HL) MR MRSA. Post-treatment nares cultures on day 3 were negative for 78.5%, 80%, and 27.7% of patients with MS MRSA, LL-MR MRSA, and HLMR MRSA, respectively. Sustained culture negativity at 1 to 4 weeks was more common in the MS MRSA group (91%) than in the LL-MR MRSA group (25%) or the HL-MR MRSA group (25%). Positive post-treatment cultures usually showed the same DNA pattern relative to baseline. Plasmid curing of 18 HL-MR MRSA resulted in 15 MS MRSA and 3 LL-MR MRSA. Mupirocin was effective in eradicating MS MRSA, but strains of MR MRSA often persisted after treatment. This appeared to reflect treatment failure rather than exogenous recolonization. MR MRSA is now more prevalent and it is appropriate to sample MRSA populations for mupirocin susceptibility prior to incorporating mupirocin into infection control programs.

Poststernotomy mediastinitis due to Staphylococcus aureus: comparison of methicillin-resistant and methicillin-susceptible cases.

The objective of the study was to compare the outcome of poststernotomy mediastinitis (PSM) caused by methicillin-resistant and methicillin-susceptible Staphylococcus aureus (MRSA and MSSA, respectively). Hospital records of 41 patients with S. aureus PSM who were all treated by closed drainage from 1 April 1996 through 1 February 2000 were reviewed. PSM was caused by MRSA in 15 patients and by MSSA in 26. Follow-up (+/-SD) averaged 12.5+/-14.0 months per patient. Both groups had similar perioperative characteristics. Patients with MRSA PSM had a significantly lower actuarial survival rate than did patients with MSSA PSM (60.0%+/-12.6%, 52.5%+/-3.4%, and 26.3%+/-19.7% versus 84.6%+/-7.1%, 79.0%+/-8.6%, and 79.0%+/-8.65 at 1 month, and at 1 and 3 years, respectively; values are +/- SD; P=.04). PSM-related death and treatment failure were significantly higher in the MRSA group than in the MSSA group (P=.03 and.02, respectively). Logistic regression analysis revealed that MRSA was the only independent risk factor for overall mortality. In conclusion, the clinical outcome of PSM caused by MRSA is poorer than that caused by MSSA.