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A case of brucellosis endocarditis, a rare complication of brucellosis, was detected as part of an undifferentiated febrile illness surveillance study conducted in Georgia. The case was further superinfected with methicillin-resistant Staphylococcus aureus (MRSA) during the hospital stay. To our knowledge, this is one of only a few reports of brucellosis endocarditis cases with MRSA superinfection.

Methicillin-resistant Staphylococcus aureus (MRSA) infections are a national concern for public health and hospital officials due to the opportunistic nature of the bacteria and the emergence of resistance to several antibiotics. In 2013, the MRSA incidence rates were 58.7 and 73.0 per 100,000 persons per year in the Department of Defense (DOD) and the Department of the Navy (DON) beneficiary populations, respectively; this is a 59% decrease for the DOD and DON since 2005. The majority of MRSA infections within the DOD and DON in 2013 were outpatient, community-associated (CA), and skin and soft tissue infections (SSTIs); similar patterns were observed since 2005. In the DOD from 2005-2013, MRSA isolates showed decreased susceptibility to cefazolin. However, MRSA showed increased susceptibility to erythromycin and cefotaxime in both the DOD and the DON, and to gentamicin in the DON only. The proportion of MRSA cases with inducible clindamycin resistance is increasing, with a 31.3% increase in the DOD and a 65.3% increase in the DON from 2005 to 2013. Military prescription practices in 2013 were consistent with treatments recommended by the Infectious Diseases Society of America (IDSA).

Methicillin Resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide. It is still one of the major problems of drug resistance and it should be a frequent and an important human pathogen both in community and in hospital. 

Over the past two decades, an epidemiologic emergence of methicillin-resistant Staphylococcus aureus (MRSA) infections has occurred from that of primarily hospital-associated to community-associated. This emergence change has involved MRSA of different pulsed-field types (PFT), with different virulence genes and antimicrobial resistance patterns. In this study, we evaluate the changes in PFT and antimicrobial resistance epidemiology of invasive MRSA isolates over 25 years at a single burn unit. Isolates were tested by pulsed-field gel electrophoresis (PFGE), broth microdilution antimicrobial susceptibility testing, and PCR for the virulence factors Panton Valentine leukocidin (PVL) and arginine catabolic mobile element (ACME), and the resistance marker staphylococcal chromosomal cassette mec (SCCmec). Forty isolates were screened, revealing stable vancomycin susceptibility MIC without changes over time but decreasing susceptibility to clindamycin and ciprofloxacin. The majority of PFGE types were MRSA USA800 carrying the SCCmec I element and USA100 carrying the SCCmec II element. No strains typically associated with community-associated MRSA, USA300 or USA400, were found. USA800 isolates were predominately found in the 1980s, USA600 isolates were primarily found in the 1990s, and USA100 isolates were found in the 2000s. The PVL gene was present in only one isolate, the sole USA500 isolate, from 1987. The virulence marker ACME was not detected in any of the isolates. Overall, a transition was found in hospital-associated MRSA isolates over the 25 years, but no introduction of community-associated MRSA isolates into this burn unit. Continued active surveillance and aggressive infection control strategies are recommended to prevent the spread of community-acquired MRSA to this burn unit.

This article is from BMC Infectious Diseases , volume 14 . Abstract None

This article is from Antimicrobial Resistance and Infection Control , volume 2 . Abstract Background: Clinicians often prescribe antimicrobials for outpatient wound infections before culture results are known. Local or national MRSA rates may be considered when prescribing antimicrobials. If clinicians prescribe in response to national rather than local MRSA trends, prescribing may be improved by making local data accessible. We aimed to assess the correlation between outpatient trends in antimicrobial prescribing and the prevalence of MRSA wound infections across local and national levels. Methods: Monthly MRSA positive wound culture counts were obtained from The Surveillance Network, a database of antimicrobial susceptibilities from clinical laboratories across 278 zip codes from 1999–2007. Monthly outpatient retail sales of linezolid, clindamycin, trimethoprim-sulfamethoxazole and cephalexin from 1999–2007 were obtained from the IMS Health XponentTM database. Rates were created using census populations. The proportion of variance in prescribing that could be explained by MRSA rates was assessed by the coefficient of determination (R2), using population weighted linear regression. Results: 107,215 MRSA positive wound cultures and 106,641,604 antimicrobial prescriptions were assessed. The R2 was low when zip code-level antimicrobial prescription rates were compared to MRSA rates at all levels. State-level prescriptions of clindamycin and linezolid were not correlated with state MRSA rates. The variance in state-level prescribing of clindamycin and linezolid was correlated with national MRSA rates (clindamycin R2 = 0.17, linezolid R2 = 0.22). Conclusions: Clinicians may rely on national, not local MRSA data when prescribing clindamycin and linezolid for wound infections. Providing local resistance data to prescribing clinicians may improve antimicrobial prescribing and would be a possible target for future interventions.

This article is from Marine Drugs , volume 11 . Abstract A new thiazolyl peptide, kocurin (1), was isolated from culture broths of a marine-derived Kocuria palustris. Its structural elucidation was accomplished using a combination of spectroscopic and chemical methods, including HRMS, extensive 1D and 2D NMR analysis, MS/MS fragmentation, and chemical degradation and Marfey’s analysis of the resulting amino acid residues. The structure herein reported corrects that previously assigned to PM181104 (3). Kocurin displayed activity against methicillin-resistant Staphylococcus aureus (MRSA), with MIC values in the submicromolar range.

This article is from Marine Drugs , volume 11 . Abstract A new thiazolyl peptide, kocurin (1), was isolated from culture broths of a marine-derived Kocuria palustris. Its structural elucidation was accomplished using a combination of spectroscopic and chemical methods, including HRMS, extensive 1D and 2D NMR analysis, MS/MS fragmentation, and chemical degradation and Marfey’s analysis of the resulting amino acid residues. The structure herein reported corrects that previously assigned to PM181104 (3). Kocurin displayed activity against methicillin-resistant Staphylococcus aureus (MRSA), with MIC values in the submicromolar range.

This article is from Marine Drugs , volume 11 . Abstract A new thiazolyl peptide, kocurin (1), was isolated from culture broths of a marine-derived Kocuria palustris. Its structural elucidation was accomplished using a combination of spectroscopic and chemical methods, including HRMS, extensive 1D and 2D NMR analysis, MS/MS fragmentation, and chemical degradation and Marfey’s analysis of the resulting amino acid residues. The structure herein reported corrects that previously assigned to PM181104 (3). Kocurin displayed activity against methicillin-resistant Staphylococcus aureus (MRSA), with MIC values in the submicromolar range.

This article is from Marine Drugs , volume 11 . Abstract A new thiazolyl peptide, kocurin (1), was isolated from culture broths of a marine-derived Kocuria palustris. Its structural elucidation was accomplished using a combination of spectroscopic and chemical methods, including HRMS, extensive 1D and 2D NMR analysis, MS/MS fragmentation, and chemical degradation and Marfey’s analysis of the resulting amino acid residues. The structure herein reported corrects that previously assigned to PM181104 (3). Kocurin displayed activity against methicillin-resistant Staphylococcus aureus (MRSA), with MIC values in the submicromolar range.

This article is from Annals of Laboratory Medicine , volume 34 . Abstract We assessed the reporting times for identification of nasal methicillin-resistant Staphylococcus aureus (MRSA) carriers in 2011 in a university-affiliated hospital using surveillance cultures incubated for 1 and 2 days with ChromID MRSA (bioMérieux, France). Of 2,732 nasal swabs tested, MRSA was detected in 829 (85.6%) and 140 (14.4%) swabs after 1 and 2 days of incubation, respectively, and the median reporting times for positive specimens were 33.7 hr (range, 18.2-156.9 hr) and 108.1 hr (range, 69.8-181.0 hr), respectively. Detection rate after 1-day incubation was 85%. Additional 1-day incubation improved detection rate; however, it prolonged the reporting times of positive specimens approximately up to 4 days because of the need for confirmatory tests such as species identification and susceptibility tests. Following a 2-day culture with ChromID MRSA, rapid confirmatory tests are warranted to reduce delay in identifying MRSA carriers.

This article is from BMJ Open , volume 4 . Abstract Objectives: The impact of surface disinfection versus detergent cleaning on healthcare associated infection rates remains unresolved. We aimed to evaluate the efficacy of hydrogen peroxide (HP) decontamination against methicillin-resistant Staphylococcus aureus (MRSA). Design: Single centred retrospective before and after study design. Setting: Launceston General Hospital, Tasmania, Australia. Participants: Patients with MRSA infection or colonisation. Interventions: Rooms occupied by patients with MRSA infection or colonisation were cleaned following discharge with either detergent or HP. Main outcome measures: MRSA room contamination following cleaning; new MRSA acquisition in patients. Results: Over 3600 discharge cleans were completed, with more than 32 600 environmental swabs processed. MRSA was isolated from 24.7% rooms following detergent cleaning and from 18.8% of rooms after HP (p

This article is from BMJ Open , volume 4 . Abstract Objectives: The impact of surface disinfection versus detergent cleaning on healthcare associated infection rates remains unresolved. We aimed to evaluate the efficacy of hydrogen peroxide (HP) decontamination against methicillin-resistant Staphylococcus aureus (MRSA). Design: Single centred retrospective before and after study design. Setting: Launceston General Hospital, Tasmania, Australia. Participants: Patients with MRSA infection or colonisation. Interventions: Rooms occupied by patients with MRSA infection or colonisation were cleaned following discharge with either detergent or HP. Main outcome measures: MRSA room contamination following cleaning; new MRSA acquisition in patients. Results: Over 3600 discharge cleans were completed, with more than 32 600 environmental swabs processed. MRSA was isolated from 24.7% rooms following detergent cleaning and from 18.8% of rooms after HP (p

This article is from BMC Infectious Diseases , volume 12 . Abstract Background: MRSA prevalence in nursing homes often exceeds that in hospitals, but reasons for this are not well understood. We sought to measure MRSA burden in a large number of nursing homes and identify facility characteristics associated with high MRSA burden. Methods: We performed nasal swabs of residents from 26 nursing homes to measure MRSA importation and point prevalence, and estimate transmission. Using nursing home administrative data, we identified facility characteristics associated with MRSA point prevalence and estimated transmission risk in multivariate models. Results: We obtained 1,649 admission and 2,111 point prevalence swabs. Mean MRSA point prevalence was 24%, significantly higher than mean MRSA admission prevalence, 16%, (paired t-test, p

This article is from Annals of Laboratory Medicine , volume 32 . Abstract Background: We compared the LightCycler MRSA advanced test (Roche Diagnostics, Germany) with enrichment culture methods to evaluate the relative diagnostic performance of the LightCycler MRSA advanced test for active surveillance in a high-prevalence setting. Methods: A total of 342 nasal swab specimens were obtained from patients in the intensive care unit at admission and on the seventh day for follow-up. The results of LightCycler MRSA advanced test were compared to those of the enrichment culture. For discrepant results, mecA gene PCR was performed. Results: For the detection of methicillin-resistant Staphylococcus aureus (MRSA), the LightCycler MRSA advanced test showed 98.5% sensitivity and 78.6% specificity and had positive and negative predictive values of 75.0% and 98.8%, respectively. A total of 46 samples had discrepant results between the LightCycler MRSA advanced test and enrichment culture. Of the 44 specimens that were positive in the LightCycler MRSA advanced test but negative by enrichment culture, mecA genes were detected in 37 specimens. In addition, of the original 44 cases, 21 patients had a history of MRSA colonization or infection within the last month; of those 21 specimens, 20 were positive for mecA gene as shown by PCR. Seven mecA-negative discrepant specimens comprised 3 methicillin-sensitive S. aureus-culture positive and only 2 patients had MRSA infections. Conclusions: Despite its low specificity and positive predictive value, the LightCycler MRSA advanced test could serve as a rapid test for patients colonized with MRSA.

This article is from PLoS ONE , volume 9 . Abstract Background: The emergence of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) has caused a change in MRSA epidemiology worldwide. In the Middle East, the persistent spread of CA-MRSA isolates that were associated with multilocus sequence type (MLST) clonal complex 80 and with staphylococcal cassette chromosome mec (SCCmec) type IV (CC80-MRSA-IV), calls for novel approaches for infection control that would limit its spread. Methodology/Principal Findings: In this study, the epidemiology of CC80-MRSA-IV was investigated in Jordan and Lebanon retrospectively covering the period from 2000 to 2011. Ninety-four S. aureus isolates, 63 (67%) collected from Lebanon and 31 (33%) collected from Jordan were included in this study. More than half of the isolates (56%) were associated with skin and soft tissue infections (SSTIs), and 73 (78%) were Panton-Valentine Leukocidin (PVL) positive. Majority of the isolates (84%) carried the gene for exofoliative toxin d (etd), 19% had the Toxic Shock Syndrome Toxin-1 gene (tst), and seven isolates from Jordan had a rare combination being positive for both tst and PVL genes. spa typing showed the prevalence of type t044 (85%) and pulsed-field gel electrophoresis (PFGE) recognized 21 different patterns. Antimicrobial susceptibility testing showed the prevalence (36%) of a unique resistant profile, which included resistance to streptomycin, kanamycin, and fusidic acid (SKF profile). Conclusions: The genetic diversity among the CC80 isolates observed in this study poses an additional challenge to infection control of CA-MRSA epidemics. CA-MRSA related to ST80 in the Middle East was distinguished in this study from the ones described in other countries. Genetic diversity observed, which may be due to mutations and differences in the antibiotic regimens between countries may have led to the development of heterogeneous strains. Hence, it is difficult to maintain “the European CA-MRSA clone” as a uniform clone and it is better to designate as CC80-MRSA-IV isolates.

This article is from BMC Veterinary Research , volume 10 . Abstract Background: The nasal microbiota of pigs has been poorly assessed but could play a role in carriage of important microorganisms such as methicillin-resistant Staphylococcus aureus (MRSA). The objectives of this study were to describe the nasal microbiota in slaughter age pigs, to evaluate the impact of farm management on the nasal microbiota and to provide a preliminary assessment of the influence of the microbiota on MRSA carriage. Results: Nasal swabs were collected from five MRSA positive and eight MRSA negative pigs on one farm that used a liquid feeding system and routine tylosin treatment, and seven MRSA negative pigs from an antibiotic-free farm that used conventional feeding. A total of 946310 sequences passed all quality control filters. The number of sequences per sample ranged from 4307 to 165656 (mean 56092, SD 40007). CatchAll analysis of richness predicted a mean of 1749 OTUs (range 213–3736, SD 996). Overall, 6291 OTUs were identified, yet 5125 (81%) were identified less than 10 times and the 12 most abundant OTUs accounted for 80.7% of sequences. Proteobacteria predominated in all but two samples. Liquid-fed/tylosin-exposed pigs had significantly lower relative abundances of Verrucomicrobia (P = 0.004), Fibrobacteres (P = 

This article is from Genome Announcements , volume 1 . Abstract We report the draft genome sequence of a methicillin-resistant strain of Staphylococcus aureus, designated MRSA-M2. This clinical isolate was obtained from an osteomyelitis patient undergoing treatment at the University of Texas Medical Branch (Galveston, TX). This strain is an ST30, spa type T019, agr III strain and has been utilized as a model S. aureus strain in a number of proteomic, transcriptomic, and animal model studies.

This article is from Genome Announcements , volume 1 . Abstract We report the draft genome sequence of a methicillin-resistant strain of Staphylococcus aureus, designated MRSA-M2. This clinical isolate was obtained from an osteomyelitis patient undergoing treatment at the University of Texas Medical Branch (Galveston, TX). This strain is an ST30, spa type T019, agr III strain and has been utilized as a model S. aureus strain in a number of proteomic, transcriptomic, and animal model studies.

This article is from Genome Announcements , volume 2 . Abstract Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (positive blood cultures after ≥7 days) represents a challenging subset of invasive MRSA infections. The comparison of genome sequences of persistent (300-169) and resolving (301-188) MRSA bacteremia isolates with similar genetic background (sequence type 45 [ST45]) will help us to better understand underlying mechanisms of persistent MRSA bacteremia.

This article is from Pharmaceuticals , volume 5 . Abstract The aim of this study is to determine the combined effects of stilbenoids from Shorea gibbosa and vancomycin against methicillin-resistant Staphylococcus aureus (MRSA). A total of nine pure compounds, five stilbenoid dimers ε-viniferin, ampelopsin A, balanocarpol, laevifonol and diptoindonesin G and four stilbenoid trimers α-viniferin, johorenol A, ampelopsin E and vaticanol G were evaluated for their antibacterial activities against ATCC 33591 and a HUKM clinical isolate. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each active compound were determined using the serial microdilution and plate-streak techniques. The combined effect of stilbenoids with vancomycin against MRSA was evaluated using the checkerboard assay to determine their fractional inhibitory concentration (FIC) index values. The MIC value of α-viniferin on both MRSA strains was 100 μg/mL, whereas those of johorenol A on ATCC 33591 and HUKM strain were 100 μg/mL and 200 μg/mL, respectively. The MIC values of ampelopsin E and vaticanol G were higher than 400 μg/mL. Out of the five stilbenoid dimers, only ε-viniferin was capable of inhibiting the growth of both MRSA strains at MIC 400 μg/mL. The MBC value of ε-viniferin, α-viniferin and johorenol A showed bacteriostatic action against MRSA. The FIC index value of ε-viniferin and α-viniferin in combination with vancomycin showed an additive effect (0.5 < FIC ≤ 2.0) against both MRSA strains. Johorenol A-vancomycin combination was also additive against HUKM strain, but it showed synergistic interaction with vancomycin against ATCC 33591 (FIC < 0.5). Stilbenoid compounds from Shorea gibbosa have anti-MRSA activity and huge potential as an alternative phytotherapy in combating MRSA infections.

Methicillin-resistant Staphylococcus aureus (MRSA) infections are a national concern for public health and hospital officials due to the opportunistic nature of the bacteria and the emergence of resistance to several antibiotics. In 2014, the MRSA incidence rates were 60.0 and 70.5 per 100,000 person years in the Department of Defense (DOD) and the Department of the Navy (DON) beneficiary populations, respectively; this is a 56.8% decrease for the DOD and a 60.4% decrease for the DON since 2005. The majority of MRSA infections within the DOD and DON in 2014 were outpatient, community-associated (CA), and skin and soft tissue infections (SSTIs). Among DOD and DON beneficiaries, MRSA isolates were most susceptible to vancomycin, linezolid, and rifampin, and least susceptible to amoxicillin/clavulanate, ceftriaxone, and cefazolin. The proportion of MRSA cases with inducible clindamycin resistance is increasing, with a 30.1% increase in the DOD and a 51.2% increase in the DON from 2005 to 2014. Military prescription practices in 2014 were consistent with treatments recommended by the Infectious Diseases Society of America (IDSA).

Methicillin-resistant Staphylococcus aureus (MRSA) infections are a national concern for public health and hospital officials due to the opportunistic nature of the bacteria and the emergence of resistance to several antibiotics. In 2014, the MRSA incidence rates were 60.0 and 70.5 per 100,000 person years in the Department of Defense (DOD) and the Department of the Navy (DON) beneficiary populations, respectively; this is a 56.8% decrease for the DOD and a 60.4% decrease for the DON since 2005. The majority of MRSA infections within the DOD and DON in 2014 were outpatient, community-associated (CA), and skin and soft tissue infections (SSTIs). Among DOD and DON beneficiaries, MRSA isolates were most susceptible to vancomycin, linezolid, and rifampin, and least susceptible to amoxicillin/clavulanate, ceftriaxone, and cefazolin. The proportion of MRSA cases with inducible clindamycin resistance is increasing, with a 30.1% increase in the DOD and a 51.2% increase in the DON from 2005 to 2014. Military prescription practices in 2014 were consistent with treatments recommended by the Infectious Diseases Society of America (IDSA).

This article is from Genome Announcements , volume 1 . Abstract Here, we report the draft genome sequences of four nosocomial methicillin-resistant Staphylococcus aureus strains (PPUKM-261-2009, PPUKM-332-2009, PPUKM-377-2009, and PPUKM-775-2009) isolated from a university teaching hospital in Malaysia. Three of the strains belong to sequence type 239 (ST239), which has been associated with sustained hospital epidemics worldwide.

This article is from Nucleic Acids Research , volume 41 . Abstract A limited number of Methicillin-resistant Staphylococcus aureus (MRSA) clones are responsible for MRSA infections worldwide, and those of different lineages carry unique Type I restriction-modification (RM) variants. We have identified the specific DNA sequence targets for the dominant MRSA lineages CC1, CC5, CC8 and ST239. We experimentally demonstrate that this RM system is sufficient to block horizontal gene transfer between clinically important MRSA, confirming the bioinformatic evidence that each lineage is evolving independently. Target sites are distributed randomly in S. aureus genomes, except in a set of large conjugative plasmids encoding resistance genes that show evidence of spreading between two successful MRSA lineages. This analysis of the identification and distribution of target sites explains evolutionary patterns in a pathogenic bacterium. We show that a lack of specific target sites enables plasmids to evade the Type I RM system thereby contributing to the evolution of increasingly resistant community and hospital MRSA.

This article is from Antimicrobial Resistance and Infection Control , volume 3 . Abstract Background: The current data regarding the correlation between the methicillin-resistant Staphylococcus aureus (MRSA) clones carried in the nasal cavity and digestive tract are inadequate. Methods: MRSA strains were isolated from both the feces and nasal swabs of 21 nasal-MRSA carriers ranging from 10 to 104 days of age treated at the neonatal intensive care units of two hospitals. The molecular epidemiological characteristics of the isolates were determined: multilocus sequence types, spa-types, staphylococcal cassette chromosome mec (SCCmec) types, carriage of four exotoxin genes, and genes contained in commercially available kit. Results: The feces of all nasal carriers contained MRSA at levels ranging from 4.0 × 102 to 2.8 × 108 colony forming units/g feces. The MRSA clones isolated from the feces and the nasal swabs of each patient were the same. Four MRSA clones, clonal complex (CC) 8-SCCmec IVl, CC8-SCCmec IVb, CC1-SCCmec IVa and CC5-SCCmec IIa were identified from 21 patients. All CC8-SCCmec IVl strains and one of three CC5-SCCmec IIa strains carried the toxic shock syndrome toxin gene. Conclusions: The feces of tested MRSA carriers contained the same MRSA clones as the nasal isolates in considerable amounts, suggesting that more careful attention should be paid for the handling of excrement in the case of newborn babies or infants than that of adults.

The EpiData Center (EDC) conducts routine surveillance of methicillin-resistant Staphylococcus aureus (MRSA) incidence and prevalence among all beneficiaries seeking care within the Military Health System (MHS). This report describes demographics, clinical characteristics, prescription practices, and antibiotic resistance patterns observed for MRSA in calendar year (CY) 2015. Multiple data sources were linked to assess descriptive and clinical factors related to MRSA. Health Level 7 (HL7)-formatted microbiology data identified S. aureus infections resistant to oxacillin, cefoxitin, or methicillin. These infections were matched to HL7-formatted pharmacy data to assess prescription practices, the Standard Inpatient Data Record (SIDR) to determine healthcare-associated exposures, Defense Manpower Data Center (DMDC) rosters to determine burden among Department of Defense (DOD) active duty (AD) service members, and the DMDC Contingency Tracking System (CTS) to determine Department of the Navy (DON) deployment-related infections. Overall, incidence rates of MRSA in the general United States (US), MHS beneficiary, and DOD AD populations are decreasing. Inducible clindamycin resistance is slowly increasing in the MHS; no additional changes in antibiotic susceptibility emerged in 2015. Clindamycin, trimethoprim/sulfamethoxazole, doxycycline, and vancomycin remain viable treatments for MRSA, although clindamycin should be used cautiously in the inpatient setting due to reduced efficacy. Current infection control practices appear effective and continued surveillance is recommended.

The EpiData Center Department (EDC) conducts routine surveillance of methicillin-resistant Staphylococcus aureus (MRSA) incidence and prevalence among all beneficiaries seeking care within the Military Health System (MHS). This report describes demographics, clinical characteristics, prescription practices, and antibiotic resistance patterns observed for MRSA in calendar year (CY) 2016. Multiple data sources were linked to assess descriptive and clinical factors related to MRSA. Health Level 7 (HL7)-formatted Composite Health Care System (CHCS) microbiology data identified S. aureus infections resistant to oxacillin, cefoxitin, or methicillin. These infections were matched to HL7-formatted CHCS pharmacy data to assess prescription practices, the Standard Inpatient Data Record (SIDR) to determine healthcare-associated exposures, Defense Manpower Data Center (DMDC) rosters to determine burden among Department of Defense (DOD) active duty (AD) service members, and the DMDC Contingency Tracking System (CTS) to determine Department of the Navy (DON) deployment-related infections. Overall, incidence rates of MRSA in the general United States (US), MHS beneficiary, and DOD AD populations are decreasing. Inducible clindamycin resistance is slowly increasing in the MHS; no additional changes in antibiotic susceptibility emerged in 2016. Clindamycin, trimethoprim/sulfamethoxazole, doxycycline, and vancomycin remain viable treatments for MRSA, although clindamycin should be used cautiously in the inpatient setting due to reduced efficacy. Current infection control practices appear effective and continued surveillance is recommended.

This article is from BMC Microbiology , volume 13 . Abstract Background: A novel variant of the ST1-SCCmecIV methicillin-resistant Staphylococcus aureus (MRSA) lineage, mostly associated with nosocomial bloodstream infections (BSI), has emerged in Rio de Janeiro. Bacterial biofilm has been considered a major virulence factor in central venous catheter-associated BSI. The mechanisms involved in biofilm formation/accumulation are multifactorial and complex. Studies have suggested that biofilm production was affected in vitro and vivo for agr-null mutants of S. aureus. Results: The impact of naturally occurring inhibition of agr signaling on virulence profiles and infections associated with the ST1 variant was investigated. agr dysfunction was detected in a significant percentage (13%) of the isolates with concomitant increase in biofilm accumulation in vitro and in vivo, and enhanced ability to adhere to and invade airway cells. The biofilm formed by these ST1 isolates was ica-independent and proteinaceous in nature. In fact, the improved colonization properties were paralleled by an increased expression of the biofilm-associated genes fnbA, spa and sasG. The transcription of sarA, a positive regulator of agr, was two-times reduced for the agr-dysfunctional MRSA. Remarkably, the agr inhibition was genetically stable. Indeed, agr-dysfunctional isolates succeed to colonize and cause both acute and chronic infections in hospitalized patients, and also to effectively accumulate biofilm in a mouse subcutaneous catheter implant model. Conclusion: The ability of agr-dysfunctional isolates to cause infections in humans and to form biofilm in the animal model suggests that therapeutic approaches based on agr-inactivation strategies are unlikely to be effective in controlling human-device infections caused by ST1 isolates. The increased biofilm accumulation associated with the acquisition of multiple antimicrobial resistant traits might have influenced (at least in part) the expansion of this USA400 related clone in our hospitals.

This article is from Iranian Journal of Basic Medical Sciences , volume 15 . Abstract Objective(s): Staphylococcus aureus (S. aureus) is a prevalent pathogen worldwide. Methicillin resistant S. aureus (MRSA), which is usually multi-resistant in hospitals, has been a daunting challenge for clinicians for more than half a century. The aim of this systematic review and meta-analysis is to determine the relative frequency (R.F.) of MRSA in different regions of Iran. Materials and Methods: Search terms “Staphylococcus aureus”, “Methicillin”, “mecA” and “Iran” were used in PubMed, Scirus and Google Scholar. Two Persian scientific search engines and ten recent national congresses were also explored. Articles/abstracts, which used clinical specimens and had done PCR to detect the mecA gene, were included in this review. Comprehensive Meta-Analysis and Meta-Analyst software were used for statistical analysis. Results: Out of 2690 results found in the mentioned databases, 48 articles were included in the final analysis. These studies were done in Ahvaz, Falavarjan, Fasa, Gorgan, Hamedan, Isfehan, Kashan, Mashhad, Sanandaj, Shahrekord, Shiraz, Tabriz, Tehran and Tonekabon. Pooled estimation of 7464 S. aureus samples showed that 52.7%±4.7 (95% confidence interval [CI]) of strains were mecA positive. MRSA R.F. in different studies varied from 20.48% to 90% in Isfehan and Tehran, respectively. We found a moderate heterogeneity (I2= 48.5%) of MRSA R.F. among studies conducted in Tehran (ranging from 28.88% to 90%, mean 52.7% [95% CI: 46.6%±0.58.8%]). Conclusion: According to the results of this study, MRSA R.F. in Iran is in the high range. Thus, measures should be taken to keep the emergence and transmission of these strains to a minimum.

This article is from International Journal of Nanomedicine , volume 9 . Abstract Silver nanoparticles (AgNPs) have been shown great interest because of their potential antibacterial effect. Recently, this has been increased due to resistance in some pathogenic bacteria strains to conventional antibiotics, which has initiated new studies to search for more effective treatments against resistant microorganisms. For these reasons, AgNPs have become an important approach for applications in nanobiotechnology in the development of antibiotic treatment of different bacterial infections. This study was aimed at synthesizing AgNPs using cysteine as a reducer agent and cetyl-tri-methyl-ammonium bromide as a stabilizer in order to obtain more efficient treatment against the pathogen bacteria Escherichia coli O157:H7. These AgNPs were characterized through UV-Vis spectroscopy, transmission electron microscopy, and dynamic light scattering. From these analyses, formation of spherical nanoparticles with an average size of 55 nm was confirmed. Finally, minimal inhibitory concentration (MIC) and minimal bactericide concentration (MBC) of these AgNPs against pathogenic strains E. coli O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) were determined in both solid and liquid media. MIC and MBC values were around 0.25 μg/mL and 1 μg/mL, respectively. These parameters were comparable to those reported in the literature and were even more effective than other synthesized AgNPs.

This article is from Journal of Antimicrobial Chemotherapy , volume 69 . Abstract Objectives: mecC methicillin-resistant Staphylococcus aureus (MRSA) represent a newly recognized form of MRSA, distinguished by the possession of a divergent mecA homologue, mecC. The first isolate to be identified came from bovine milk, but there are few data on the prevalence of mecC MRSA among dairy cattle. The aim of this study was to conduct a prevalence study of mecC MRSA among dairy farms in Great Britain. Methods: Test farms were randomly selected by random order generation and bulk tank samples were tested for the presence of mecC MRSA by broth enrichment and plating onto chromogenic agar. All MRSA isolated were screened by PCR for mecA and mecC, and mecC MRSA were further characterized by multilocus sequence typing, spa typing and antimicrobial susceptibility testing. Results: mecC MRSA were detected on 10 of 465 dairy farms sampled in England and Wales (prevalence 2.15%, 95% CI 1.17%–3.91%), but not from 625 farms sampled in Scotland (95% CI of prevalence 0%–0.61%). Seven isolates belonged to sequence type (ST) 425, while the other three belonged to clonal complex 130. Resistance to non-β-lactam antibiotics was uncommon. All 10 isolates produced a negative result by slide agglutination for penicillin-binding protein 2a. mecA MRSA ST398 was detected on one farm in England. Conclusions: mecC MRSA is widely distributed among dairy farms in Great Britain, but this distribution is not uniform across the whole country. These results provide an important baseline dataset to monitor the epidemiology of this emerging form of MRSA.

This article is from PLoS ONE , volume 8 . Abstract In order to test whether rooks (Corvus frugilegus) represent good indicators for the potential circulation of antibiotics in their native habitat, two populations with different migratory behavior were tested for the presence of beta-lactamase producing Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA). In all, 54 and 102 samples of fresh feces of a migratory and a resident population were investigated. A total of 24 and 3 cefotaxime-resistant enterobacterial isolates were obtained from the migratory and resident population, respectively. In these isolates CTX-M-1 (n = 15), CTX-M-3 (n = 3), and CTX-M-15 (n = 3) genes were detected. TEM-1 and OXA-1 were associated with CTX-M in 3 and 2 isolates, respectively. In two E. coli isolates CMY-2 could be detected, where from one isolate displayed an overexpression of chromosomal AmpC as well. Among E. coli isolates the most common phylogenetic group was A (n = 11) and ST1683 (n = 5). In one E. coli of B2-ST131 the rfbO25b locus was detected. Three Enterobacter isolates were stably derepressed AmpC-producers. In five samples of the migratory population, PVL positive MRSA could be isolated. Two isolates were typed SCCmec IVa, spa type t127, and ST1. Three isolates carried a SCCmec type IVc, with spa type t852 and ST22. The highly significant difference of the occurrence of antibiotic resistance between the migratory population from eastern Europe compared to resident population in our study indicates that rooks may be good indicator species for the evaluation of environmental contamination with antibiotic resistant bacteria, especially due to their ecology, foraging behavior and differing migratory behavior.

Aim: Various levels of reduced susceptibility to glycopeptides are emerging with increasing frequency in Staphylococcus aureus (S. aureus) strains. We aimed to determine Vancomycin minimum inhibitory concentration (MIC)s for Methicillin-resistant S. aureus (MRSA) strains isolated from blood cultures between 2012-2015 and to evaluate changes in Vancomycin MIC levels over the years (2007-2015) at our institution.  Material and Method: A total of 45 MRSA blood culture isolates between 2012 and 2015 were studied. MIC de-terminations for Vancomycin were performed using Etest method. The mean MIC and geometric mean MIC were calculated for each year and the differences between the years were analyzed. These results were then evaluated together with the results of our previous study performed between 2007 and 2011.  Results: There was no Vancomycin-resistant S. aureus (VRSA) or Vancomycin-intermediate S. aureus (VISA) among the isolates. Only one strain was evaluated as heteroresistant Vancomycin-intermediate S. aureus (hVISA). When compared, there were significant differences between the years (2012-2015) for the mean MICs (p=0.027) and the trend in the increase in the Vancomycin mean MICs over the years was found to be significant (p=0.005). When the results of both studies were evaluated together, there were significant differences between the years (2007-2015) for the mean MICs (p=0.001) and the upward trend in the Vancomycin mean MICs over the years was found to be significant (p&lt;0.001).  Discussion: We observed an increase in Vancomycin MICs for MRSA blood culture isolates over the years at our hospital. It is important to monitor local Vancomycin MICs in invasive MRSA isolates systematically.