Evaluation of antimicrobial photodynamic action of a pluronic and pectin based film loaded with methylene blue against methicillin resistantStaphylococcus aureus.

Antimicrobial wound dressings play a crucial role in treatment of wound infections. However, existing commercial options fall short due to antibiotic resistance and the limited spectrum of activity of newly emerging antimicrobials against bacteria that are frequently encountered in wound infections. Antimicrobial photodynamic therapy (aPDT) is very promising alternative therapeutic approach against antibiotic resistant microbes such as methicillin resistantStaphylococcus aureus (MRSA). However, delivery of the photosensitizer (PS) homogeneously to the wound site is a challenge. Though polymeric wound dressings based on synthetic and biopolymers are being explored for aPDT, there is paucity of data regarding theirin vivoefficacy. Moreover, there are no studies on use of PS loaded, pluoronic (PL) and pectin (PC) based films for aPDT. We report development of a polymeric film for potential use in aPDT. The film was prepared using PL and PC via solvent casting approach and impregnated with methylene blue (MB) for photodynamic inactivation of MRSAin vitroandin vivo. Atomic force microscopic imaging of the films yielded vivid pictures of surface topography, with rough surfaces, pores, and furrows. The PL:PC ratio (2:3) was optimized that would result in an intact film but exhibit rapid release of MB in time scale suitable for aPDT. The film showed good antibacterial activity against planktonic suspension, biofilm of MRSA upon exposure to red light. Investigations on MRSA infected excisional wounds of mice reveal that topical application of MB loaded film for 30 min followed by red light exposure for 5 min (fluence; ∼30 J cm-2) or 10 min (fluence; ∼60 J cm-2) reduces ∼80% or ∼92% of bioburden, respectively. Importantly, the film elicits no significant cytotoxicity against keratinocytes and human adipose derived mesenchymal stem cells. Taken together, our data demonstrate that PS-loaded PL-PC based films are a promising new tool for treatment of MRSA infected wounds.

Comparative activities of sitafloxacin against recent clinical isolates in hospitals across China.

Sitafloxacin is one of the newer generation fluoroquinolones. Considering the ever-changing antimicrobial resistance, it is necessary to monitor the activities of sitafloxacin against recent pathogenic isolates. Therefore, we determined the minimum inhibitory concentrations (MICs) of sitafloxacin and comparators by broth microdilution or agar dilution method against 1101 clinical isolates collected from 2017 to 2019 in 31 hospitals across China. Sitafloxacin was highly active against gram-positive isolates evidenced by the MICs required to inhibit the growth of 50%/90% isolates (MIC50/90): ≤ 0.03/0.25, ≤ 0.03/0.125, ≤ 0.03/2, 0.125/0.25, 0.25/2, and 0.125/0.125 mg/L for methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-susceptible coagulase-negative Staphylococcus (MSCNS), methicillin-resistant S. aureus (MRSA), methicillin-resistant CNS, Enterococcus faecalis, and Streptococcus pneumoniae, respectively. Sitafloxacin inhibited 82.8% of the MRSA strains and 97.5% of MRCNS strains. Sitafloxacin was also potent against ciprofloxacin-susceptible Escherichia coli (MIC50/90: ≤ 0.03/0.06 mg/L) and Klebsiella pneumoniae (MIC50/90: ≤ 0.03/0.125 mg/L), non-ESBL-producing E. coli (MIC50/90: ≤ 0.03/1 mg/L) and K. pneumoniae (MIC50/90: ≤ 0.03/0.5 mg/L), Haemophilus influenzae (MIC50/90: ≤0.015/0.06 mg/L), Haemophilus parainfluenzae (MIC50/90: 0.125/0.5 mg/L), Moraxella catarrhalis (MIC50/90: ≤ 0.015/≤ 0.015 mg/L), Bacteroides fragilis (MIC50/90: 0.06/2 mg/L), Peptostreptococcus (MIC50/90: 0.125/4 mg/L), and Mycoplasma pneumoniae (≤ 0.03/≤ 0.03 mg/L). However, sitafloxacin was less active for Enterococcus faecium, ciprofloxacin-resistant and/or ESBL-producing E. coli, and K. pneumoniae strains. Sitafloxacin was superior or comparable to most of the comparators in activities against the abovementioned isolates, so sitafloxacin is still highly active against most of the clinical isolates in hospitals across China, proving its utility in treatment of the abovementioned susceptible strains.

Determining spa-type of methicillin-resistant Staphylococcus aureus (MRSA) via high-resolution melting (HRM) analysis, Shiraz, Iran.

OBJECTIVES: Molecular typing methods are useful for rapid detection and control of a disease. Recently, the use of high-resolution melting (HRM) for spa typing of MRSA isolates were reported. This technique is rapid, inexpensive and simple for genotyping and mutation screening in DNA sequence. The aim of this study was to evaluate the ability of HRM-PCR to analysis spa genes amongst MRSA isolates. RESULTS: A total of 50 MRSA isolates were collected from two teaching hospitals in Shiraz, Iran. The isolates were confirmed as MRSA by susceptibility to cefoxitin and detection of mecA gene using PCR. We used HRM analysis and PCR-sequencing method for spa typing of MRSA isolates. In total, 15 different spa types were discriminate by HRM and sequencing method. The melting temperature of the 15 spa types, using HRM genotyping were between 82.16 and 85.66 °C. The rate of GC % content was 39.4-46.3. According to the results, spa typing of 50 clinical isolates via PCR-sequencing and HRM methods were 100% similar. Consequently, HRM method can easily identify and rapidly differentiate alleles of spa genes. This method is faster, less laborious and more suitable for high sample at lower cost and risk of contamination.

Prevalence and characteristics of Livestock-Associated Methicillin-Resistant Staphylococcus aureus (LA-MRSA) isolated from chicken meat in the province of Quebec, Canada.

This study was conducted to estimate the prevalence of Livestock-Associated Methicillin-Resistant Staphylococcus aureus (LA-MRSA) in retail chicken meat and broiler chickens from the Province of Quebec, Canada, and to characterize LA-MRSA isolates. A total of 309 chicken drumsticks and thighs were randomly selected in 2013 from 43 retail stores in the Monteregie. In addition, nasal swabs and caeca samples were collected in 2013-2014 from 200 broiler chickens of 38 different flocks. LA-MRSA was not detected in broiler chickens. Fifteen LA-MRSA isolates were recovered from four (1.3%) of the 309 chicken meat samples. Multi-Locus Sequence Typing (MLST) and SCCmec typing revealed two profiles (ST398-MRSA-V and ST8-MRSA-IVa), which were distinct using pulse-field gel electrophoresis (PFGE) and microarray (antimicrobial resistance and virulence genes) analyses. In addition to beta-lactam resistance, tetracycline and spectinomycin resistance was detected in all isolates from the 3 positive samples of the ST398 profile. Southern blot hybridization revealed that the resistance genes aad(D) and lnu(A), encoding resistances to aminoglycosides and lincosamides respectively, were located on plasmid. All isolates were able to produce biofilms, but biofilm production was not correlated with hld gene expression. Our results show the presence of two separate lineages of MRSA in retail chicken meat in Quebec, one of which is likely of human origin.

Spread of seb-Positive Methicillin-Resistant Staphylococcus aureus SCCmec Type II-ST764 Among Elderly Japanese in Nonacute Care Settings.

We investigated the prevalence and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) among 356 residents of nine long-term care facilities (LTCFs) in Japan during 2015 and 2017. In total, 800 specimens were tested and 39 MRSA isolates were recovered from 31 (8.71%) residents. PCR-based open reading frame typing (POT) and pulsed-field gel electrophoresis typing were performed for the 39 MRSA isolates; five of them showing identical pulsotypes, and POT scores were excluded in further analysis. Staphylococcal cassette chromosome mec (SCCmec) typing, multilocus sequence typing, and toxin gene detection were performed for one representative MRSA isolate per resident. Among the 34 unrelated MRSA isolates, 15 (44.1%) and 19 (55.9%) were of SCCmec types II and IV, respectively, and belonged to seven sequence types (STs). Among the 15 SCCmec II isolates, 11 (73.3%), 3, and 1 belonged to ST764 (clonal complex [CC]5), ST5 (CC5), and ST630 (CC8), respectively. Among the 19 SCCmec IV isolates, 13 (68.4%), 3, 2, and 1 belonged to ST1 (CC1), ST474 (CC1), ST8 (CC8), and ST380 (CC8), respectively. Among the 14 CC5 lineage-SCCmec II isolates, one ST5 isolate and 7 of the 11 ST764 isolates (63.6%) carried seb gene, and 14 (87.5%) of 16 CC1 lineage-SCCmec IV isolates had sea gene (p < 0.05). The results indicate that the seb-positive SCCmec type II-ST764 clone has spread in Japanese LTCF environments. As LTCF residents have multiple comorbidities and increased susceptibility to infections, it is necessary to monitor MRSA colonization in LTCFs through periodic screening to prevent dissemination.

In Vitro Activity of Tedizolid in Comparison with Other Oral and Intravenous Agents Against a Collection of Community-Acquired Methicillin-Resistant Staphylococcus aureus (2014-2015) in the United States.

Tedizolid activity was compared with other agents with oral and intravenous formulations against community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). Tedizolid (MIC50/90, 0.12/0.12 mg/L; 100.0% susceptible) was the most potent agent tested against CA-MRSA and subsets from adult and pediatric patients. Tedizolid minimum inhibitory concentrations (MICs) were twofold to fourfold lower than daptomycin (MIC50/90, 0.25/0.5 mg/L; 99.9-100% susceptible) and fourfold to eightfold lower than linezolid (MIC50/90, 1/1 mg/L; 100.0% susceptible), ceftaroline (MIC50/90, 0.5-1/1 mg/L; 96.6-98.8% susceptible), and vancomycin (MIC50/90, 0.5-1/1 mg/L; 100.0% susceptible) against CA-MRSA and subsets. Clindamycin resistance rates among CA-MRSA from pediatric and adult patients were 18.3-19.1% (13.4-14.2% constitutive, 4.9-6.4% inducible) and 36.2-37.6% (29.8-30.1% constitutive, 6.4-7.5% inducible), respectively. Tetracycline (90.4-96.4% susceptible) and trimethoprim-sulfamethoxazole (96.2-100.0% susceptible) were active against CA-MRSA or subsets, whereas erythromycin (83.8-89.4% nonsusceptible) and levofloxacin (50.2-70.8% nonsusceptible) had limited activities. Tedizolid had MIC50/90 values of 0.12/0.12 mg/L against CA-MRSA showing clindamycin constitutive-resistance and recovered from adult or pediatric patients. Tedizolid had potent activities against CA-MRSA, regardless of clindamycin phenotype or patient population. Tedizolid may be considered for the treatment of ABSSSI in adults. Further studies are warranted for the clinical development in the pediatric population.

Antibiotic resistance among bacterial conjunctival pathogens collected in the Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) surveillance study.

The Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) surveillance study evaluates in vitro antibiotic resistance among Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Pseudomonas aeruginosa, and Haemophilus influenzae isolates from ocular infections. Here we report resistance rates and trends among conjunctival-sourced ocular isolates collected across the US from 2009 through 2016. A total of 1198 conjunctival isolates (483 S. aureus, 305 CoNS, 208 H. influenzae, 118 S. pneumoniae, and 84 P. aeruginosa) were collected from patients with presumed bacterial conjunctivitis from 57 sites across 40 states. A large proportion of staphylococci demonstrated resistance to oxacillin and azithromycin, while resistance was low against the majority of antibiotics tested for S. pneumoniae, P. aeruginosa, and H. influenzae. Multidrug resistance (≥3 antibiotic classes) was found in 30.2% of S. aureus and 39.0% of CoNS isolates, and methicillin resistance more than doubled the rate of multi-drug resistance (methicillin-resistant S. aureus [MRSA], 76.5%; methicillin-resistant CoNS isolates, 72.8%). There was a pattern of increasing mean percent resistance with increasing age by decade of life among S. aureus, MRSA, and CoNS (P≤0.038). Over the eight-year study period, there were small yet significant decreases in resistance rates among S. aureus to azithromycin, ciprofloxacin, tobramycin, trimethoprim, and oxacillin (P≤0.003), and among CoNS and P. aeruginosa (both P<0.05) to ciprofloxacin. These data indicate that antibiotic resistance is high, but did not increase, among conjunctival-sourced isolates collected in the US from 2009 through 2016. For certain antibiotic/pathogen combinations, there was a trend of decreased resistance, including a decrease in oxacillin resistance among S. aureus.

Identification of botanicals with potential therapeutic use against methicillin-resistant Staphylococcus aureus (MRSA) infections.

Staphylococcus aureus is an opportunistic pathogen. Over- and improper-use of pharmaceuticals against S. aureus has led to the development of antibiotic resistance, including methicillin-resistant S. aureus (MRSA). This study examined the efficacy of botanical extracts as an alternative form of treatment to S. aureus and MRSA, including penicillin/methicillin-resistant S. aureus (PenR ), and multidrug resistant S. aureus (MDR). Initial screening of botanicals was done via a minimum inhibitory concentration procedure. In addition, a temporal growth curve was performed in order to quantify the growth of the bacteria in the presence of the extracts. Results demonstrated 13 botanicals that had varying activities against S. aureus, PenR , and MDR. These botanicals were separated into mild, moderate, and highly efficacious based on the concentration needed to inhibit bacterial growth. These results propose a comparison of botanical-derived antimicrobial extracts that may be utilized against S. aureus and different antibiotic resistant strains of MRSA.

Characterization of SCCmec and spa types of methicillin-resistant Staphylococcus aureus isolates from health-care and community-acquired infections in Kerman, Iran.

Spread of methicillin-resistant Staphylococcus aureus (MRSA) isolates is a worldwide problem. Molecular typing is a useful tool to understand MRSA epidemiology. Herein, we determined vancomycin-resistant, SCCmec and spa types among MRSA isolates recovered from healthcare and community-acquired infections in Kerman, Iran. A total of 170 S. aureus isolates were collected from different patients who were admitted to affiliated hospitals of Kerman University of Medical science. MRSA and vancomycin-resistant S. aureus (VRSA) isolates were detected by phenotypic methods. Polymerase chain reaction (PCR) technique was used for detection of mecA, vanA and vanB genes. Staphylococcal cassette chromosomemec (SCCmec) and spa typing were used for molecular typing of among MRSA isolates. Overall, 53% of isolates were considered as MRSA. Two MRSA isolates were resistant to vancomycin and vanA was detected in only one of VRSA isolates. SCCmec type III belonged to spa types t030 and t459 which they were the dominant spa types among community-associated MRSA (CA-MRSA) and healthcare-acquired MRSA (HA-MRSA) isolates. Our findings showed that the SCCmec type I and III spread from hospital settings to community, although the SCCmec type IV spread from community to healthcare systems. We have also reported VRSA isolates from hospitalized patients, therefore, appropriate policies should be enforced in order to prevent the spread of antibiotic resistance isolates in hospitals settings.

Antibiotic susceptibility profiles of ocular and nasal flora in patients undergoing cataract surgery in Taiwan: an observational and cross-sectional study.

OBJECTIVE: To investigate the conjunctival and nasal flora and the antibiotic susceptibility profiles of isolates from patients undergoing cataract surgery. DESIGN: Observational and cross-sectional study. SETTING: A single-centre study in Taiwan. PARTICIPANTS: 128 consecutive patients precataract surgery. PRIMARY AND SECONDARY OUTCOME MEASURES METHODS: Conjunctival and nasal cultures were prospectively obtained from 128 patients on the day of cataract surgery before instillation of ophthalmic solutions in our hospital. Isolates and antibiotic susceptibility profiles were identified through standard microbiological techniques. Participants were asked to complete a questionnaire on healthcare-associated factors. RESULTS: The positive culture rate from conjunctiva was 26.6%, yielding 84 isolates. Coagulase-negative Staphylococci were the most commonly isolated organisms (45.2%), and 35% of staphylococcal isolates were methicillin-resistant. Among staphylococcal isolates, all were susceptible to vancomycin, and 75%-82.5% were susceptible to fluoroquinolones. Methicillin-resistant isolates were significantly less susceptible than their methicillin-sensitive counterparts to tobramycin, the most commonly used prophylactic antibiotic in our hospital (28.6% vs 69.2%; p=0.005). The positive culture rate from nares for Staphylococcus aureus was 21.9%, and six isolates were methicillin-resistant. No subjects had S. aureus colonisation on conjunctiva and nares simultaneously. There were no associated risk factors for colonisation of methicillin-resistant Staphylococci. CONCLUSION: The most common conjunctival bacterial isolate of patients undergoing cataract surgery was coagulase-negative Staphylococci in Taiwan. Because of predominant antibiotic preferences and selective antibiotic pressures, Staphylococci were more susceptible to fluoroquinolones but less to tobramycin than in other reports. Additionally, methicillin-resistant Staphylococci exhibited co-resistance to tobramycin but not to fluoroquinolones.

Efficacy of Ceftaroline against Methicillin-Susceptible Staphylococcus aureus Exhibiting the Cefazolin High-Inoculum Effect in a Rat Model of Endocarditis.

Certain Staphylococcus aureus strains exhibit an inoculum effect (InE) with cefazolin (CFZ) that has been associated with therapeutic failures in high-inoculum infections. We assessed the in vitro activities of ceftaroline (CPT), CFZ, and nafcillin (NAF) against 17 type A ß-lactamase (ßla)-producing, methicillin-susceptible S. aureus (MSSA) strains, including the previously reported TX0117, which exhibits the CFZ InE, and its ßla-cured derivative, TX0117c. Additionally, we determined the pharmacokinetics of CPT in rats after single intramuscular doses of 20 and 40 mg/kg of body weight and evaluated the activities of CPT (40 mg/kg every 8 h [q8h]), CFZ, and NAF against TX0117 and TX0117c in a rat model of infective endocarditis. No InE was observed for CPT or NAF, whereas a marked InE was detected for CFZ (MIC, 8 to ≥128 µg/ml). CPT and NAF treatment against TX0117 resulted in mean bacterial counts of 2.3 and 2.1 log10 CFU/g in vegetations, respectively, compared to a mean of 5.9 log10 CFU/g in the CFZ-treated group (CPT and NAF versus CFZ, P = 0.001; CPT versus NAF, P = 0.9830). Both CFZ and CPT were efficacious against the ßla-cured derivative, TX0117c, compared to time zero (t0) (P = <0.0001 and 0.0015, respectively). Our data reiterate the in vivo consequences of the CFZ InE and show that CPT is not affected by this phenomenon. CPT might be considered for high-inoculum infections caused by MSSA exhibiting the CFZ InE.

Ceftaroline-Resistant, Daptomycin-Tolerant, and Heterogeneous Vancomycin-Intermediate Methicillin-Resistant Staphylococcus aureus Causing Infective Endocarditis.

We report a case of infective endocarditis (IE) caused by ceftaroline-resistant, daptomycin-tolerant, and heterogeneous vancomycin-intermediate methicillin-resistant S. aureus (MRSA). Resistance to ceftaroline emerged in the absence of drug exposure, and the E447K substitution in the active site of PBP2a previously associated with ceftaroline resistance was identified. Additionally, we present evidence of patient-to-patient transmission of the strain within the same unit. This case illustrates the difficulties in treating MRSA IE in the setting of a multidrug-resistant phenotype.

Molecular and Phenotypic Characterization Revealed High Prevalence of Multidrug-Resistant Methicillin-Susceptible Staphylococcus aureus in Chongqing, Southwestern China.

Methicillin-susceptible Staphylococcus aureus (MSSA) accounts for ∼40% of staphylococcal infections in China. However, the molecular characterization of MSSA is not well described. In this study, 124 MSSA strains collected in 2013 from a comprehensive teaching hospital in Chongqing, Southwestern China, were subjected to antibiotics susceptibility testing and molecular typing, including multilocus sequence typing, staphylococcal protein A (spa) gene typing, accessory gene regulator (agr) typing, pulsed-field gel electrophoresis (PFGE) typing, Panton-Valentine leukocidin (pvl) gene detection, and antibiotic-resistant gene detection. MSSA strains exhibited high genetic heterogeneity. A total of 10 PFGE groups, 26 sequence types, and 47 spa types were identified. Type I (62.9%) was the most frequent agr type, followed by type II (15.3%), type IV (11.3%), and type III (10.5%). The prevalence of pvl genes was 27.4% (34/124). Notably, 44.4% (55/124) of MSSA strains were multidrug resistance (MDR), and MDR isolates were mostly resistant to penicillin, erythromycin, and clindamycin. The resistance gene blaZ was present in 84.7% of strains, ermC was present in 85.5% of strains, ermA was present in 28.2% of strains, tetK was present in 16.1% of strains, tetM was present in 6.5% of strains, and aacA-aphD was present in 2.6% of strains. These data demonstrated the high prevalence of MDR MSSA in Chongqing, thereby indicating the need to control MSSA infection.

Clinical outcomes and antibiotic susceptibilities of Staphylococcus aureus endophthalmitis.

PURPOSE: To compare the antibiotic susceptibilities and visual acuity (VA) outcomes in endophthalmitis caused by methicillin-resistant (MRSA) versus methicillin-sensitive S. aureus (MSSA). METHODS: The records of 34 cases of S. aureus endophthalmitis at The New York Eye and Ear Infirmary from Jan 1997 to June 2011 were reviewed. Antibiotic susceptibility profiles over time and VA at presentation and at 3, 6, and ≥12 months were recorded. S. aureus isolates were grouped based on oxacillin resistance. RESULTS: Of the 34 cases, 15 (44 %) were MRSA and 19 (56 %) MSSA. Median presenting VA was hand motions (logMAR 4.0) in both the MRSA and MSSA groups. There was no statistically significant difference in VA between the MRSA and MSSA groups at 3, 6, or ≥12 months. No MRSA isolates were resistant to vancomycin or gentamicin. While over 85 % of MRSA isolates tested for fourth-generation fluoroquinolones were resistant, just 10 % MSSA isolates tested were resistant. There was a trend suggesting an increase in the proportion of MRSA isolates compared to MSSA isolates over the course of the study period. CONCLUSIONS: There was no statistical difference in short- or long-term VA outcomes between the MRSA and MSSA groups at any time point. Resistance to fourth-generation fluoroquinolones was present in over 85 % of MRSA isolates, but just 10 % of MSSA isolates. An increasing proportion of MRSA amongst S. aureus isolates was noted over the course of the study period.

Using MRSA Screening Tests To Predict Methicillin Resistance in Staphylococcus aureus Bacteremia.

Bloodstream infections with Staphylococcus aureus are clinically significant and are often treated with empirical methicillin resistance (MRSA, methicillin-resistant S. aureus) coverage. However, vancomycin has associated harms. We hypothesized that MRSA screening correlated with resistance in S. aureus bacteremia and could help determine the requirement for empirical vancomycin therapy. We reviewed consecutive S. aureus bacteremias over a 5-year period at two tertiary care hospitals. MRSA colonization was evaluated in three ways: as tested within 30 days of bacteremia (30-day criterion), as tested within 30 days but accounting for any prior positive results (ever-positive criterion), or as tested in known-positive patients, with patients with unknown MRSA status being labeled negative (known-positive criterion). There were 409 S. aureus bacteremias: 302 (73.8%) methicillin-susceptible S. aureus (MSSA) and 107 (26.2%) MRSA bacteremias. In the 167 patients with MSSA bacteremias, 7.2% had a positive MRSA test within 30 days. Of 107 patients with MRSA bacteremia, 68 were tested within 30 days (54 positive; 79.8%), and another 21 (19.6%) were previously positive. The 30-day criterion provided negative predictive values (NPV) exceeding 90% and 95% if the prevalence of MRSA in S. aureus bacteremia was less than 33.4% and 19.2%, respectively. The same NPVs were predicted at MRSA proportions below 39.7% and 23.8%, respectively, for the ever-positive criterion and 34.4% and 19.9%, respectively, for the known-positive criterion. In MRSA-colonized patients, positive predictive values exceeded 50% at low prevalence. MRSA screening could help avoid empirical vancomycin therapy and its complications in stable patients and settings with low-to-moderate proportions of MRSA bacteremia.

The Impact of Reporting a Prior Penicillin Allergy on the Treatment of Methicillin-Sensitive Staphylococcus aureus Bacteremia.

BACKGROUND: Methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia is a morbid infection with mortality benefit from receipt of parenteral ß-lactam therapy. A substantial portion of MSSA bacteremia patients report penicillin allergy, but infrequently have true allergy. OBJECTIVE: To determine the frequency and predictors of optimal and adequate therapy in patients with MSSA bacteremia. DESIGN: Retrospective cohort. PARTICIPANTS: Adult inpatients with MSSA bacteremia, January 2009 through October 2013. MAIN MEASURES: The primary measure was a trial of optimal therapy (OT), defined as ≥3 inpatient days or discharge on any first-line agents (nafcillin, oxacillin, cefazolin, or penicillin G, if susceptible). The secondary measure was completion of adequate therapy (AT), defined as ≥10 inpatient days or discharge on an agent appropriate for MSSA bacteremia. Data were electronically gathered with key variables manually validated through chart review. Log-binomial regression models were used to determine the frequency and predictors of outcomes. KEY RESULTS: Of 456 patients, 346 (76%) received a trial of OT. Patients reporting penicillin allergy (13%) were less likely to receive OT trial than those without penicillin allergy (47% vs. 80%, p <0.001). Adjusting for other factors, penicillin allergy was the largest negative predictor of OT trial (RR 0.64 [0.49, 0.83]). Infectious Disease (ID) consultation was the largest positive predictor of OT trial across all patients (RR 1.34 [1.14, 1.57]). Allergy/Immunology consultation was the single most important predictor of OT trial among patients reporting penicillin allergy (RR 2.33 [1.44, 3.77]). Of 440 patients, 391 (89%) completed AT, with ID consultation the largest positive predictor of the outcome (RR 1.28 [1.15, 1.43]). CONCLUSIONS: Nearly 25% of patients with MSSA bacteremia did not receive OT trial and about 10% did not receive AT completion. Reported penicillin allergy reduced, and ID consult increased, the likelihood of OT. Allergy evaluation, coupled with ID consultation, may improve outcomes in MSSA bacteremic patients.

Methicillin-Susceptible, Vancomycin-Resistant Staphylococcus aureus, Brazil.

We report characterization of a methicillin-susceptible, vancomycin-resistant bloodstream isolate of Staphylococcus aureus recovered from a patient in Brazil. Emergence of vancomycin resistance in methicillin-susceptible S. aureus would indicate that this resistance trait might be poised to disseminate more rapidly among S. aureus and represents a major public health threat.

Could ceftaroline be an alternative therapy for linezolid resistant Staphylococcus epidermidis infections in Intensive Care Medicine?

INTRODUCTION: Coagulase negative Staphylococcus continues generating interest in critically ill patients, due to their infections in extended admissions, in instrumented patients and due to their described multidrug resistance, which include glycopeptide heterorresistance and the increase in oxazolidinone resistance. Ceftaroline is a new cephalosporin with activity against resistant gram-positives, which, being betalactam, may provide adequate safety profile in the critical ill patient. The aim of this study was to determine the activity of ceftaroline and other antimicrobial agents against methicillin and linezolid-resistant Staphylococcus epidermidis. MATERIAL AND METHODS: We studied susceptibility of ceftaroline, tigecycline, daptomycin and vancomycin in a total of sixty-eight methicillin and linezolid-resistant S. epidermidis isolates with clinical significance from an Intensive Care Unit, using E-test. RESULTS: All strains were susceptible to the four antimicrobial agents, regardless of the level of resistance to linezolid. CONCLUSION: Ceftaroline could be an alternative in the treatment of methicillin and linezolid-resistant S. epidermidis infections in critically ill patients.

Improved outcome with early rifampicin combination treatment in methicillin-sensitive Staphylococcus aureus bacteraemia with a deep infection focus - a retrospective cohort study.

INTRODUCTION: Rifampicin has been used as adjunctive therapy in Staphylococcus aureus bacteraemia (SAB) with a deep infection focus. However, data for prognostic impact of rifampicin therapy is unestablished including the optimal initiation time point. We studied the impact of rifampicin therapy and the optimal initiation time for rifampicin treatment on prognosis in methicillin-sensitive S. aureus bacteraemia with a deep infection. METHODS: Retrospective, multicentre study in Finland including 357 SAB patients with a deep infection focus. Patients with alcoholism, liver disease or patients who died within 3 days were excluded. Patients were categorised according to duration of rifampicin therapy and according to whether rifampicin was initiated early (within 7 days) or late (7 days after) after the positive blood cultures. Primary end point was 90 days mortality. RESULTS: Twenty-seven percent of patients received no rifampicin therapy, 14% received rifampicin for 1-13 days whereas 59% received rifampicin ≥14 days. The 90 day mortality was; 26% for patients treated without rifampicin, 16% for rifampicin therapy of any length and 10% for early onset rifampicin therapy ≥14 days. Lack of rifampicin therapy increased (OR 1.89, p=0.026), rifampicin of any duration decreased (OR 0.53, p=0.026) and rifampicin therapy ≥14 days with early onset lowered the risk for a fatal outcome (OR 0.33, p<0.01) during 90 days follow-up. CONCLUSION: Rifampicin adjunctive therapy for at least 14 days and initiated within 7 days of positive blood culture associated with improved outcome among SAB patients with a deep infection.