Multiresistant Methicillin-resistant Staphylococcus Aureus Research Articles

In-Vitro Methicillin-Resistant Staphylococcus Aureus Photobiomodulation Eradication by Ultraviolet Light

Photobiomodulation eradication by Ultraviolet Light (UVL) 254 nm wavelengths exerts bactericidal effects, it was used in the disinfection. UVL showed anti Methicillin-resistant Staphylococcus aureus (MRSA) effects where using 280/300nm, with 4Dt value of 5 s observed in the bacterial suspension of 5 log CFU/mL as inactivation. UVL anti-bacterial spores cell wall, harm to DNA, RNA, and proteins by photo-hydration, photo-splitting, photo-crosslinking, and photo-dimerization. The aim was to use photobiomodulation eradication UVL methods for multi resistant MRSA that it had severe infection. So, it can help in disinfection and kill MRSA without chemical treatment. Preparation of MRSA strains, using "LED Apparatus"; the method was "Photobiomodulation Eradication by UVL". The results were presented the “Wavelengths (280+300) nm, were from (0-30 second)”. It was found from the result that the five MRSA strains gave a similar result, and the difference was noted that it was due to the characteristics of each MRSA strain alone and the resistance genes it contained. As for the result, it was very impressive to 30 minutes to completely eliminate all MRSA strains. It was concluded from the results that this photobiomodulation eradicated by UVL method was used to sterilize and eliminated MRSA strains that have drug multi resistance antibiotics within 30 seconds. It was recommended for using this photobiomodulation eradicated by UVL method to eliminate the multi resistance antibiotics strains that infect the skin. That could be through "Pharmacy Technology" to produce the dose that can be used for ski treatment without any harm to the patient.

Panton-Valentine leukocidin and staphylococcal cassette chromosome mec characterization of community acquired methicillin-resistant Staphylococcus aureus.

Staphylococcus aureus (SA) represents one of the most important microorganism that is part of the normal microflora of humans, but in certain conditions can cause very serious infections. Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for a wide spectrum of nosocomial and community associated infections worldwide. The aim of this study was to determine community acquired MRSA (CA-MRSA), as well as the frequency of Panton-Valentine leukocidin (PVL) genes and staphylococcal cassette chromosome mec (SCCmec) types in isolates obtained from outpatients in the region of 700,000 people (Canton Sarajevo, Bosnia and Herzegovina) Methods: Our investigation included phenotypic and genotypic markers such as antimicrobial resistance, pulsed-field gel electrophoresis (PFGE), SCC typing, and PVL detection. Antimicrobial susceptibility: all MRSA isolates were resistant to the β-lactam antibiotics tested, and all isolates were susceptible to trimethoprim sulphamethoxazole, rifampicin, fusidic acid, linezolid, and vancomycin. After the PFGE analysis, the isolates were grouped into five similarity groups: A-E. The largest number of isolates belonged to one of two groups: C - 60% and D - 27%. In both groups C and D, SCCmec type IV was predominant (60% and 88.8%, respectively). A total of 24% of the isolates had positive expression of PVL genes, while 76% showed a statistically significantly greater negative expression of PVL genes. Using combination techniques, we were able to investigate the origin and genetic background of the strains. PFGE analysis revealed two large, genetically related groups of strains consisting of 87 isolates. Our results suggest failure to apply the screening policy, and a lack of knowledge about multiresistant MRSA strains. This study showed the local epidemiological situation which should be the basis of antimicrobial empiric therapy for non-hospitalized patients.

Monitoring of multiresistant community-associated MRSA strains from patients with pathological processes of different localization

The therapy of infections, caused by methicillin-resistant Staphylococcus aureus (MRSA) with multiple resistance to antibiotics remains one of the most acute problems all over the world. It is all the more complicated since a priori the MSRA strains are not sensitive to the group of β-lactam antibiotics and multiresistant isolates are resistant to other groups of antimicrobial preparations, including antibiotics of choice (rifampicin, vancomycin, fusidic acid, co-trimoxazole and linezolid). From the samples of biomaterials of patients with pathological processes of different localization, we isolated 335 strains of bacteria, which were identified as Staphylococcus aureus, 169 (50.4%) of which were methicillin-resistant variants: 57.5% cultures were isolated from the nasal discharge; 50.7% – from faeces at intestinal dysbioses; by 40.0% – from conjunctival discharge, pharyngeal swab, outer ear swab and sputum; 33.3% – from urine samples. Antibiotic susceptibility of the isolated cultures was estimated by the disc-diffusion method and the method of serial dilution. The MRSA strains appeared to be most resistant to gentamycin, erythromycin (by 59.5% of cultures) and ciprofloxacin (53.3% of isolates), most sensitive – to vancomycin, co-trimoxazole and fusidic acid. The frequency of isolation of the cultures that are resistant to antibiotics did not exceed 4.1%. Rifampicin suppressed the growth of 75.8% and linezolid – of 100.0% of strains. Depending on the kind of biomaterial taken, MRSA strains, isolated from the nasal cavity, outer ear, urine samples, samples of sputum and faeces at intestinal dysbioses proved to be most resistant to the tested antimicrobial preparations. Rifampicin- and vancomycin-resistant strains of methicillin-resistant staphylococci made up 21.3% of the total number of the detected MRSA. They were most often isolated from the clinical samples taken from the nasal cavity and faeces. When determining minimal inhibitory concentration (MIC) of rifampicin and vancomycin, which are antibiotics of choice for treatment of infections caused by multiresistant MRSA, it was found that for 55.5% of the MRSA strains isolated from faeces, MIC of rifampicin coincided with the threshold value for this antibiotic and for 44.5%, it exceeded the threshold value by 2 times (4 µg/ml). 22.2% of them were characterized by the critical value of susceptibility to vancomycin (MIC ≥ 2 µg/ml). From rifampicin- and vancomycin-resistant MRSA stains, isolated from the nasal cavity, MIC of rifampicin coincided with the threshold value for this antibiotic for 66.7% of cultures, and exceeded it at least by 2 times for 33.3%. 11.1% of them were characterized by the critical level of susceptibility to vancomycin (MIC ≥ 2 µg/ml) and by 3.7% of strains exceeded MIC by 2 and 4 times respectively (4 and 8 µg/ml).

Optimizing the detection of methicillin-resistant Staphylococcus aureus with elevated vancomycin minimum inhibitory concentrations within the susceptible range.

BackgroundDetermination of vancomycin minimum inhibitory concentration (MIC) can influence the agent used to treat methicillin-resistant Staphylococcus aureus (MRSA) infection. We studied diagnostic accuracy using E-test and VITEK® 2 against a gold standard broth microdilution (BMD) methodology, the correlation between methods, and associations between vancomycin MIC and MRSA phenotype from clinical isolates.MethodsMRSA isolates were obtained from April 2012 to December 2013. Vancomycin MIC values were determined prospectively on all isolates by gradient diffusion E-test and automated VITEK® 2. The Clinical and Laboratory Standards Institute reference BMD method was performed retrospectively on thawed frozen isolates. Diagnostic accuracy for detecting less susceptible strains was calculated at each MIC cutoff point for E-Test and VITEK® 2 using BMD ≥1 µg/mL as a standard. The correlation between methods was assessed using Spearman’s rho (ρ). The association between MRSA phenotype and MIC for the three methods was assessed using Fisher’s exact test.ResultsOf 148 MRSA isolates, all except one (E-test =3 µg/mL) were susceptible to vancomycin (MIC of ≤2 µg/mL) irrespective of methodology. MICs were ≥1.0 µg/mL for 9.5% of BMD, 50.0% for VITEK® 2, and 27.7% for E-test. Spearman’s ρ showed weak correlations between methods: 0.29 E-test vs VITEK® 2 (P=0.003), 0.27 E-test vs BMD (P=0.001), and 0.31 VITEK® 2 vs BMD (P=0.002). The optimal cutoff points for detecting BMD-defined less susceptible strains were ≥1.0 µg/mL for E-test and VITEK® 2. E-test sensitivity at this cutoff point was 0.85 and specificity 0.29, while VITEK® 2 sensitivity and specificity were 0.62 and 0.51, respectively. Multiresistant MRSA strains tended to have higher MIC values compared to nonmultiresistant MRSA or epidemic MRSA 15 phenotypes by E-test (Fisher’s exact P<0.001) and VITEK® 2 (Fisher’s exact P<0.001).ConclusionOverall diagnostic accuracy and correlations between MIC methods used in routine diagnostic laboratories and the gold standard BMD showed limited overall agreement. This study helps optimize guidance on the effective use of vancomycin.

Rifampicin resistance among multi-resistant MRSA clinical isolates from Chennai, India, and their molecular characterization.

High-level methicillin-resistant Staphylococcus aureus (MRSA) isolates show rapid evolution of rifampicin resistance, forcing reliance upon expensive and often inferior antibiotics to manage these infections. Accordingly, this study was conducted to: 1) evaluate the level of multidrug resistance among hospital-associated MRSA isolates from Chennai, India; 2) determine their rifampicin resistance and molecular characterization; and 3) analyze the identified rpoB gene mutations for predominant high-level rifampicin resistance-associated nucleotide changes. Conventional laboratory techniques and antibiogram evaluation by disc diffusion were utilized for isolate phenotypic identification. Among the 54 isolates obtained, 74% (42) were found to be MRSA. All the isolates exhibited complete susceptibility to linezolid and vancomycin, and variable resistance to conventional antibiotics; the MAR index value calculated was 0.64. Genotypic identification of the high-level rifampicin-resistant isolate S. aureus KM05 was established through rpoB amplification and sequencing. The evolutionary relationship of KM05 to other isolates and its rpoB gene mutation status was determined to understand the genetic basis of its high rifampicin resistance. The S. aureus KM05 rpoB gene yielded ≥ 98% sequence similarity and a close phylogenetic relationship with other known reference database organisms. It also showed mutational changes in three rpoB codon positions encoding amino acids at positions 455, 481, and 529. These results have established the prevalence of rifampicin resistance among Chennai hospital MRSA isolates, and suggest that the predominant high-level resistance nucleotide changes would serve to form a basis for their diagnosis and control of rifampicin-resistant MRSA.

High prevalence of Panton-Valentine leukocidin (PVL) genes in nosocomial-acquired Staphylococcus aureus isolated from tertiary care hospitals in Nepal.

Methicillin-resistant Staphylococcus aureus (MRSA) carrying the important virulence determinant, Panton-Valentine leukocidin (PVL), is an emerging infectious pathogen associated with skin and soft tissue infections as well as life-threatening invasive diseases. In carrying out the first PVL prevalence study in Nepal, we screened 73 nosocomial isolates of S. aureus from 2 tertiary care Nepali hospitals and obtained an overall PVL-positivity rate of 35.6% among the hospital isolates: 26.1% of MRSA and 51.9% of methicillin sensitive S. aureus (MSSA) isolates were found to be positive for the PVL genes. PVL prevalence was not associated with a specific (i) infection site, (ii) age group, or (iii) hospital of origin. It was found to be positively associated with heterogeneous MRSA (73.3%) compared to homogeneous MRSA (3.2%) and MSSA (51.9%); negatively associated with multiresistant MRSA (22%) compared to nonmultiresistant MRSA (60%) and MSSA (51.9%); and positively associated with macrolide-streptogramin B resistance (93.8%) compared to macrolide-lincosamide-streptogramin B resistance (0%) and no-resistance (45.8%) types. Macrolide-streptogramin B resistance was confirmed by the presence of msr(A) gene. Restriction pattern analyses provided evidence to support the circulation of a limited number of clones of PVL-positive MRSA, arguing for the adaptability of these isolates to a hospital setting.

Emergence and control of an outbreak of infections due to Panton-Valentine leukocidin positive, ST22 methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit

Methicillin resistant Staphylococcus aureus (MRSA) infection can cause significant morbidity and mortality in neonates. We investigated a nosocomial MRSA outbreak in a neonatal intensive care unit (NICU), using a novel typing method. Following two fatal cases, in May 2011, a prospective outbreak investigation was conducted, involving neonates, mothers and healthcare workers in a large tertiary NICU in Sydney. MRSA isolates were characterized by antimicrobial susceptibility testing, a multiplex PCR-based reverse line blot (mPCR/RLB) binary typing system and other molecular typing methods. Over 7 months, 14 neonates were colonized with MRSA and six infected: three with superficial lesions and three with life-threatening disease, including the two index cases, who died despite empirical treatment with vancomycin. Isolates from 15 neonates were indistinguishable by RLB typing and identified as a PVL-producing ST22 SCCmec IV MRSA strain, which was resistant to gentamicin and trimethoprim-sulphamethoxazole. The outbreak strain was also isolated from one healthcare worker, one environmental swab and one father, but the source remained obscure. During the same period several different non-multiresistant and multiresistant MRSA strains were isolated from five neonates, five mothers (including two whose infants were colonized with the outbreak strain), one father, three healthcare workers and two environmental swabs. Rapid turnaround time of typing results allowed us to recognize and define the outbreak and implement targeted infection control interventions. PVL-producing ST22 SCCmec IV MRSA appears to be a virulent and highly transmissible pathogen in the NICU, which was difficult to control.

Prevalence, risk factors and genetic diversity of methicillin-resistant Staphylococcus aureus carried by humans and animals across livestock production sectors

This study aimed to assess the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in animals and humans on veal, dairy, beef and broiler farms and to compare the risk for human MRSA carriage with that of strictly horticulture farmers. The genetic background, resistance phenotypes and genotypes and toxin gene content of the isolated MRSA strains were compared with MRSA collected on MRSA clonal complex (CC)398-positive pig farms. MRSA carriage isolates were genotyped (spa, SCCmec and multilocus sequence typing), resistance to 16 antimicrobials was determined and resistance and toxin genes were detected. MRSA carriage rates were higher (P<0.01) on veal farms (calves, 64%; farmers, 72%) compared with on dairy (cows, 1%), beef (cows, 5%; farmers, 11%), broiler (pooled broths, 5%; farmers, 3%) and horticulture (farmers, 3%) farms. The intensity of animal contact was identified as a risk factor for human MRSA carriage. The vast majority of MRSA (n=344), including those from pigs, were CC398 (98%). SCCmec V(5C2), V(5C2&5)c, IV(2B) and IV(2B&5) predominated. MRSA CC130 and CC599 carrying mecC were detected in beef and dairy cattle. MRSA from veal calves were significantly more resistant than MRSA from pigs (P<0.01). A few isolates, including mecC-carrying MRSA, harboured pyrogenic superantigen toxins. Human- and animal-derived MRSA from individual farms showed similar characteristics. This systematic cross-sector survey revealed a high prevalence of multiresistant livestock-associated MRSA on Belgian veal calf farms as compared with other farm types. MRSA harbouring mecC was detected at a low frequency in beef and dairy cows, but not in humans.

Changing Trends in Resistance Pattern of Methicillin Resistant Staphylococcus aureus

Methicillin resistance in Staphylococcus aureus is associated with multidrug resistance, an aggressive course, increased mortality and morbidity in both community and health care facilities. Monitoring of newly emerging and prevalent Methicillin Resistant Staphylococcus aureus (MRSA) strains for their resistance patterns to conventional as well as novel drugs, are essential for infection control. To study the changing trends in resistance patterns of MRSA at our hospital. This cross sectional study was carried out in a 750 bed tertiary care hospital in south India. One hundred and two clinical isolates of MRSA which were obtained in 2004-2011 were identified by using oxacillin, cefoxitin disc diffusion test and oxacillin screening agar test. Antibiotic susceptibility test was done for commonly used non beta lactam anti-Staphylococcal drugs, as well as for anti-MRSA drugs like vancomycin, linezolid, mupirocin and rifampicin. Minimum inhibitory concentration (MIC) of vancomycin was determined by using Vancomycin HiComb strip (Himedia, Mumbai, India). Statistical Analysis which was done: Chi-square test and proportions were used to compare the two groups. MRSA isolates showed high resistance to co-trimoxazole (82.3%), ciprofloxacin (76.4%), gentamicin (64.7%) and tetracycline (49%) as compared to other drugs. High prevalence of ciprofloxacin resistance was detected, particularly among outpatients. Multi resistant MRSA with a ≥ 3 non-beta lactam agent resistance was 79%. All MRSA isolates were sensitive to vancomycin, linezolid, mupirocin and rifampicin. MRSA had displayed increase in resistance to most antibiotics except tetracycline in recent years. Taking into consideration the prevalence of multidrug resistance in MRSA, resistance patterns should be evaluated periodically and antibiotic therapy should be guided by susceptibility testing.

Emergence of Multiresistant Methicillin‐Resistant Staphylococcus aureus in Two Patients with Atopic Dermatitis Requiring Linezolid Treatment

We report two patients with atopic dermatitis who developed methicillin-resistant Staphylococcus aureus (MRSA) skin infections resistant to clindamycin and trimethoprim-sulfamethoxazole requiring repeated linezolid treatment. For one patient and family members who received an aggressive regimen of staphylococcal decolonization, including intranasal mupirocin, dilute bleach baths, and bleach cleansing of household items and surfaces, subsequent culture results demonstrated methicillin-susceptible S. aureus colonization and infection. These findings underscore the challenges presented by multiresistant MRSA infections in children with atopic dermatitis.

Fitness cost: a bacteriological explanation for the demise of the first international methicillin-resistant Staphylococcus aureus epidemic

Denmark and several other countries experienced the first epidemic of methicillin-resistant Staphylococcus aureus (MRSA) during the period 1965-75, which was caused by multiresistant isolates of phage complex 83A. In Denmark these MRSA isolates disappeared almost completely, being replaced by other phage types, predominantly only penicillin resistant. We investigated whether isolates of this epidemic were associated with a fitness cost, and we employed a mathematical model to ask whether these fitness costs could have led to the observed reduction in frequency. Bacteraemia isolates of S. aureus from Denmark have been stored since 1957. We chose 40 S. aureus isolates belonging to phage complex 83A, clonal complex 8 based on spa type, ranging in time of isolation from 1957 to 1980 and with various antibiograms, including both methicillin-resistant and -susceptible isolates. The relative fitness of each isolate was determined in a growth competition assay with a reference isolate. Significant fitness costs of 2%-15% were determined for the MRSA isolates studied. There was a significant negative correlation between number of antibiotic resistances and relative fitness. Multiple regression analysis found significantly independent negative correlations between fitness and the presence of mecA or streptomycin resistance. Mathematical modelling confirmed that fitness costs of the magnitude carried by these isolates could result in the disappearance of MRSA prevalence during a time span similar to that seen in Denmark. We propose a significant fitness cost of resistance as the main bacteriological explanation for the disappearance of the multiresistant complex 83A MRSA in Denmark following a reduction in antibiotic usage.

A multilevel model of methicillin-resistant Staphylococcus aureus acquisition within the hierarchy of an Australian tertiary hospital

Hospitals without universal single room accommodations typically contain multibed cubicles within wards. In this study, we examined whether the variation in a patient's risk for acquiring methicillin-resistant Staphylococcus aureus (MRSA) in a major tertiary hospital was greatest at the bed, cubicle, or ward level, and quantified the risk of MRSA acquisition associated with exposure to MRSA-colonized/infected patients within the same bed, cubicle, and ward at differently distributed lag times. Nested tri-level hierarchical logistic regression models with random effects were used for non-multiresistant MRSA (nmMRSA) and multiresistant MRSA (mMRSA). The models were internally validated. Receiver operating characteristic curves were used to compare the models' predictive capability The odds of new nmMRSA acquisition were 6.06-fold (95% credible intervals [CrI], 3.93- to 9.34-fold) greater in bed-weeks when a nmMRSA-colonized/infected patient was in the same cubicle 2 weeks earlier. The odds of mMRSA acquisition were 5.12-fold (95% CrI, 4.02- to 6.51-fold) greater in bed-weeks when a colonized/infected patient was in the same ward 2 weeks earlier. The between-cluster variance was highest at the ward level. Patients were at greater risk if there was a colonized/infected patient in the same cubicle or ward 2 weeks earlier. Our findings indicate that focusing on the relevant cubicles and wards during this high-risk period can help target infection control resources more efficiently.

Polyclonal non multiresistant methicillin resistant Staphylococcus aureus isolates from clinical cases of infection occurring in Palermo, Italy, during a one-year surveillance period

BackgroundThe evolving epidemiology of methicillin resistant Staphylococcus aureus (MRSA) is characterized by the emergence of infections caused by non multiresistant MRSA carrying staphylococcal chromosomal cassette (SCC)mec IV or V in the healthcare settings. A molecular epidemiological analysis of non multiresistant MRSA isolates from four acute general hospitals was performed in Palermo, Italy, during a one year period.MethodsFor the purpose of the study, MRSA isolates were defined as non multiresistant when they were susceptible to at least three classes of non β-lactam antibiotics. Seventy-five isolates were submitted to antimicrobial susceptibility testing, multilocus sequence typing (MLST) and polymerase chain reaction (PCR) for SCCmec, accessory gene regulator (agr) groups, arginine catabolic mobile element (ACME) and Panton Valentine leukocidin (PVL) toxin genes. For epidemiological typing, Multiple-Locus Variable-Number Tandem Repeat Fingerprinting (MLVF) was performed on all isolates and pulsed field gel electrophoresis (PFGE) on ST8 isolates.ResultsNon multiresistant MRSA isolates were isolated from all hospitals. Resistances to ciprofloxacin, macrolides and tetracycline were the most prevalent. MLST attributed 46 isolates with ST22, 13 with ST8, eight with ST1, three with ST50 and three with ST398. SCCmec type IV was found in all isolates. PVL was detected in one ST22 isolate. All isolates tested negative for the ACME element. MLVF identified 31 different patterns, some subtype clusters ranging in size between two and 22 isolates. The closely related PFGE patterns of the ST8 isolates differed from USA300.ConclusionsA polyclonal circulation of non multiresistant MRSA along with blurring of boundaries between healthcare associated (HA)-MRSA and community associated (CA)-MRSA appear to be occurring in our epidemiological setting. A better understanding of spread of MRSA with the support of molecular typing can provide invaluable information in the epidemiological, microbiological and clinical fields.

Methicillin-resistant Staphylococcus aureus vancomycin susceptibility testing: methodology correlations, temporal trends and clonal patterns

To determine the correlation between various vancomycin MIC testing methodologies and explore the phenomenon of MIC creep. A total of 417 consecutive non-duplicate methicillin-resistant Staphylococcus aureus (MRSA) bloodstream isolates from Liverpool Hospital between 1997 and 2008 were retrieved. All isolates were classified using PFGE and underwent susceptibility testing for vancomycin using a standard Etest (AB bioMérieux, Solna, Sweden), Vitek2(®) (AST-P612; bioMérieux, Inc., Durham, NC, USA) and broth microdilution (BMD) performed as per the CLSI method. Over the 12 years, 78% (n = 326) of the isolates were multiresistant MRSA (ST239-like by PFGE, where ST stands for sequence type). The correlation between MIC testing methods was moderate with Spearman's correlation coefficients of 0.50 for BMD versus Etest (P < 0.001), 0.33 for BMD versus Vitek2(®) (P < 0.001) and 0.42 for Etest versus Vitek2(®) (P < 0.001). In general, Etest results were 1 dilution higher while the Vitek2(®) results were 1 dilution lower than the BMD MIC result. MIC creep was dependent on the MIC testing method and the measurement used for analysis (geometric mean MIC versus modal MIC versus frequency analysis), with creep detected for Etest regression analysis only. In contrast, the proportion of isolates with a BMD MIC ≥2 mg/L decreased from 16% to 9% in the latter half of the study. Modal MIC was stable over the 12 years at 1 mg/L irrespective of MIC method used. Correlation between vancomycin MIC methodologies remains suboptimal. Temporal MIC trends should be interpreted with caution as these are dependent on the testing methodology and the measurement used for analysis.

The increase of methicillin-resistant Staphylococcus aureus(MRSA) and the presence of an unusual sequence type ST49 in slaughter pigs in Switzerland

BackgroundIn years past, methicillin-resistant S. aureus (MRSA) has been frequently detected in pigs in Europe, North America and Asia. Recent, yet sporadic studies have revealed a low occurrence of MRSA in Switzerland. In 2009, a monitoring survey of the prevalence and genetic diversity of methicillin-resistant S. aureus (MRSA) in slaughter pigs in Switzerland was conducted using methods recommended by the EU guidelines, and using a sampling strategy evenly distributed throughout the year and representative of the Swiss slaughter pig population. Monitoring should determine if the overall prevalence of MRSA in the entire country is increasing over the years and if specific multi-resistant MRSA clones are spreading over the country.ResultsIn 2009, the nasal cavities of eight out of 405 randomly selected pigs were positive for MRSA, representing a prevalence of 2.0% (95% CI 0.9-3.9). The following year, 23 out of 392 pigs were positive for MRSA [5.9% prevalence (95% CI 3.8-8.7)]. Three multilocus sequence types (ST), four spa types and two types of staphylococcal cassette chromosome mec (SCCmec) elements were detected. The most frequent genotypes were ST398 (MLST)-(spa)t034-V(SCCmec) (n = 18) and ST49-t208-V (n = 7), followed by ST398-t011-V (n = 4), ST398-t1451-V (n = 1), and ST1-t2279-IVc (n = 1). The isolates displayed resistance to ß-lactams [mecA, (31/31); blaZ, (19/31)]; tetracycline [tet(M), (31/31); tet(K), (30/31)] (n = 31); macrolides and lincosamides [erm(C) (4/31) or erm(A) (18/31)] (n = 22); tiamulin [vga(A)v (9/31) or unknown mechanism (18/31)] (n = 27); trimethoprim [dfr(G) (18/31); spectinomycin [ant(9)-Ia (19/31) or unknown mechanism (3/31)] (n = 22); streptomycin [str (19/31)]; sulphamethoxazole (7/31) and ciprofloxacin (n = 1) (mechanisms not determined).ConclusionsThis study is the first to describe the presence of MRSA ST49 in slaughter pigs, and to demonstrate a significant and nearly three-fold increase of MRSA prevalence in pigs within two years. The presence of a specific clonal lineage of MRSA from Switzerland suggests that it has been selected in Swiss pig husbandry. Effective hygiene measures should be enhanced within the entire pig production chain to suppress the spread of these pathogens into the community.

Molecular characterisation of methicillin-resistant Staphylococcus aureus (MRSA) from keratitis patients: a microbiological analysis

BackgroundIn order to diagnose and characterise a major corneal infection, ‘keratitis,’ which can lead to blindness, molecular studies were conducted to assess the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) strains...

Genotyping of methicillin-resistant Staphylococcus aureus isolates obtained in the Northeast region of Brazil

Methicillin-resistant Staphylococcus aureus (MRSA) is a major agent of hospital infections worldwide. In Brazil, a multiresistant MRSA lineage (ST239-SCCmecIIIA), the so-called Brazilian epidemic clone (BEC), has predominated in all regions. However, an increase in nosocomial infections caused by non-multiresistant MRSA clones has recently been observed. In the present study, 45 clinical isolates of MRSA obtained from a university hospital located in Natal city, Brazil, were identified by standard laboratory methods and molecularly characterized using staphylococcal chromosome cassette mec (SCCmec) typing and pulsed-field gel electrophoresis. Antimicrobial susceptibility testing was carried out using CLSI methods. The MRSA isolates studied displayed a total of 8 different pulsed-field gel electrophoresis patterns (types A to H) with predominance (73%) of pattern A (BEC-related). However, MRSA harboring SCCmec type IV were also identified, 3 (7%) of which were genetically related to the pediatric clone--USA800 (ST5-SCCmecIV). In addition, we found a considerable genetic diversity within BEC isolates. MRSA displaying SCCmecIV are frequently susceptible to the majority of non-beta-lactam antibiotics. However, emergence of multiresistant variants of USA800 was detected.

Molecular Characterization of Methicillin-Resistant &lt;i&gt;Staphylococcus aureus&lt;/i&gt; Clones from a Teaching Hospital in Tehran

A total of 52 methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates were collected from patients attending the teaching hospital of Tehran University of Medical Sciences. Disks containing antibiotics were used to determine the susceptibility of MRSA isolates. Analysis of SmaI macrorestriction profiles of the 52 MRSA isolates were grouped into three PFGE types. The majority of isolates (n = 49) were clustered into only one major PFGE type, designated as pulsotype A; these belonged to SCCmec type III or IIIA and showed resistance to ampicillin, ciprofloxacin, cotrimoxazole, erythromycin, gentamicin, and tetracycline. The remaining isolates fell into pulsotypes B and C, both belonging to SCCmec-type IV. All MRSA isolates were susceptible to vancomycin, teicoplanin, quinupristin-dalfopristin, linezolid, and tigecycline. The present study shows that a MRSA clone similar to the Brazilian clone (ST 239) of MRSA, which is a multiresistant MRSA clone with a high level of methicillin resistance, is very common in this teaching hospital in Tehran.

Adult methicillin-resistant Staphylococcus aureus bacteremia in Taiwan: clinical significance of non–multi-resistant antibiogram and Panton–Valentine leukocidin gene

It is poorly defined whether or not adult patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia with a non–multi-resistant antibiogram phenotype and Panton–Valentine leukocidin (PVL) gene carriage have different clinical syndromes. Clinical characteristics of 95 adult patients of MRSA bacteremia, with isolates that were non–multi-resistant to non–β-lactam, were compared with a contemporaneous multiresistant group. Independent risk factors other than community-associated MRSA bacteremia patients associated with recovery of non–multi-resistant MRSA isolates by multivariate analysis included deep-seated infection and catheter insertion site infection. Older age, intensive care unit-onset bacteremia, and postoperative infection were negative independent risk factors associated with non–multi-resistant MRSA isolates. Most of the 60 recoverable non–multi-resistant MRSA isolates belonged to multilocus sequence type 59, and all isolates belonged to staphylococcal chromosomal cassette mec (SCC mec) element type IV or type V. Most PVL-positive MRSA isolates belonged to SCC mec V. PVL-positive CA-MRSA isolates could cause more deep-seated infections in patients presented with non–multi-resistant MRSA bacteremia.

Prevalence and susceptibility pattern of methicillin- resistant Staphylococcus aureus isolates among healthy women in Zaria, Nigeria

Multi-resistant methicillin-resistant Staphylococcus aureus (MMRSA) has been commonly reported to be one of the commonest causes of nosocomial infections worldwide. Also, recent reports describe methicillin-resistant S. aureus (MRSA) carriage in persons in the community. The study investigated its prevalence in urine of healthy women and its susceptibility pattern to other antibiotics. Urine samples collected from healthy women volunteers in Zaria were cultured and screened for S. aureus using standard microbiological procedures. The isolates were then subjected to antibiotic susceptibility testing using disc diffusion technique. A total of 54 (36%) S. aureus isolates were isolated from 150 urine samples collected. The prevalence rate for married and single women was 31% and 46%, respectively. Of the S. aureus isolates, 37 (69%) were methicillin-resistant. The MRSA were highly resistant to ampicillin 100%, cephalexin 100%, clindamycin 92%, vancomycin 89% but had low resistance to pefloxacin 35%, ofloxacin 27% ciprofloxacin 27%, sparfloxacin 24% and gentamicin 16%. All the 37 (100%) MRSA isolates showed resistance to at least two antibiotics tested while 33 (89.2%) were multi-drug resistant.