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Clinical Infectious Diseases : An... Sep 2020Cefazolin and ertapenem combination therapy was used successfully to salvage 11 cases (6 endocarditis) of persistent methicillin-susceptible Staphylococcus aureus (MSSA)...
Cefazolin and ertapenem combination therapy was used successfully to salvage 11 cases (6 endocarditis) of persistent methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia, including immediate clearance (≤24 hours) in 8 cases. While in vitro synergy was modest, cefazolin plus ertapenem exhibited synergistic action in a rat model of MSSA endocarditis. The combination of cefazolin and ertapenem provides potent in vivo activity against MSSA beyond what is predicted in vitro and warrants further clinical study in the treatment of refractory MSSA bacteremia and endocarditis.
Topics: Animals; Anti-Bacterial Agents; Bacteremia; Cefazolin; Ertapenem; Methicillin; Rats; Salvage Therapy; Staphylococcal Infections; Staphylococcus aureus
PubMed: 31773134
DOI: 10.1093/cid/ciz995 -
Clinical Microbiology Reviews Apr 1988Strains of staphylococci resistant to methicillin were identified immediately after introduction of this drug. Methicillin-resistant strains have unusual properties, the... (Review)
Review
Strains of staphylococci resistant to methicillin were identified immediately after introduction of this drug. Methicillin-resistant strains have unusual properties, the most notable of which is extreme variability in expression of the resistance trait. The conditions associated with this heterogeneous expression of resistance are described. Methicillin resistance is associated with production of a unique penicillin-binding protein (PBP), 2a, which is bound and inactivated only at high concentrations of beta-lactam antibiotics. PBP2a appears to be encoded by the mec determinant, which also is unique to methicillin-resistant strains. The relationships between PBP2a and expression of resistance and implications for the mechanism of resistance are discussed. The heterogeneous expression of methicillin resistance by staphylococci poses problems in the detection of resistant strains. Experience with several susceptibility test methods is reviewed and guidelines for performance of these tests are given. Treatment of infections caused by methicillin-resistant staphylococci is discussed. Vancomycin is the treatment of choice. Alternatives have been few because methicillin-resistant strains often are resistant to multiple antibiotics in addition to beta-lactam antibiotics. New agents which are active against methicillin-resistant staphylococci are becoming available, and their potential role in treatment is discussed.
Topics: Bacteriological Techniques; Humans; Methicillin; Penicillin Resistance; Staphylococcal Infections; Staphylococcus aureus
PubMed: 3069195
DOI: 10.1128/CMR.1.2.173 -
British Medical Journal Jul 1961
Topics: Methicillin; Penicillins; Staphylococcal Infections
PubMed: 13724105
DOI: 10.1136/bmj.2.5243.6 -
Journal of Dairy Science Jun 2016Staphylococcus aureus is involved in a wide variety of diseases in humans and animals, and it is considered one of the most significant etiological agents of...
Staphylococcus aureus is involved in a wide variety of diseases in humans and animals, and it is considered one of the most significant etiological agents of intramammary infection in dairy ruminants, causing both clinical and subclinical infections. In this study, the intra-farm prevalence and circulation of methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) were investigated on an Italian dairy sheep farm previously identified as MRSA-positive by testing bulk tank milk (first isolation in 2012). Human samples (nasal swabs, hand skin samples, and oropharyngeal swabs) from 3 persons working in close contact with the animals were also collected, and the genetic characteristics and relatedness of the MRSA isolates from human and animal sources within the farm were investigated. After 2yr from the first isolation, we confirmed the presence of the same multidrug-resistant strain of MRSA sequence type (ST)1, clonal complex (CC)1, spa type t127, staphylococcal cassette chromosome mec (SCCmec) type IVa, showing identical pulsed field gel electrophoresis (PFGE) and resistance profiles at the farm level in bulk tank milk. Methicillin-resistant S. aureus isolates were detected in 2 out of 556 (0.34%) individual milk samples, whereas MSSA isolates were detected in 10 samples (1.8%). The MRSA were further isolated from udder skin samples from the 2 animals that were MRSA-positive in milk and in 2 of the 3 examined farm personnel. All MRSA isolates from both ovine and human samples belonged to ST(CC)1, spa type t127, SCCmec type IVa, with some isolates from animals harboring genes considered markers of human adaptation. In contrast, all MSSA isolates belonged to ruminant-associated CC130, ST700, spa type t528. Analysis by PFGE performed on selected MRSA isolates of human and animal origin identified 2 closely related (96.3% similarity) pulsotypes, displaying only minimal differences in gene profiles (e.g., presence of the immune evasion cluster genes). Although we observed low MRSA intra-farm prevalence, our findings highlight the importance of considering the possible zoonotic potential of CC1 livestock-associated MRSA, in view of the ability to persist over years at the farm level. Biosecurity measures and good hygiene practices could be useful to prevent MRSA spread at the farm level and to minimize exposure in the community and in categories related to farm animal industry (e.g., veterinarians, farmers, and farm workers).
Topics: Animals; Anti-Bacterial Agents; Farms; Humans; Methicillin; Methicillin Resistance; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Sheep; Staphylococcal Infections; Staphylococcus aureus
PubMed: 27060817
DOI: 10.3168/jds.2016-10912 -
Iranian Biomedical Journal Jul 2016The aim of this study was to compare the biofilm formation and the prevalence of biofilm-associated genes between the isolates of methicillin-resistant (MRSA) and... (Comparative Study)
Comparative Study
BACKGROUND
The aim of this study was to compare the biofilm formation and the prevalence of biofilm-associated genes between the isolates of methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) Staphylococcus aureus.
METHODS
In total, 209 S. aureus isolates were collected. The antibiotic susceptibility test was conducted using nine antibiotics according to the guidelines of Clinical and Laboratory Standards Institute. Phenotypic biofilm formation was performed with microtiter plate assay. The polymerase chain reaction was employed to detect icaA, icaD, icaB, icaC, clfA, clfB, fnbA, fnbB, fib, cna, eno, ebps, bbp, mecA, and SCCmec types as well as agr group genes with specific primers.
RESULTS
Sixty-four (30.62%) isolates were resistant to methicillin, and 54 (83%) MRSA harbored SCCmec III. Furthermore, 122 (58.3%) isolates belonged to agr group I. Twenty-six (36.1%) MRSA and 42 (28.9%) MSSA isolates were strong biofilm producers (no significant difference). The prevalence of icaA, icaD, icaB, and icaC genes in MSSA isolates was 71, 41, 76, and 72%, respectively. The frequency of clfA, clfB, fnbA, fnbB, fib, cna, eno, ebps, and bbp in MSSA was 100, 100, 56, 46, 74, 54, 78, 11, and 1%, respectively. However, in MRSA isolates, the frequency was 97, 97, 64, 51, 76, 56, 79, and 12% with no track of bbp, respectively.
CONCLUSION
Statistical difference between MSSA and MRSA regarding biofilm formation and the frequency of all biofilm-encoding genes was not significant. The majority of the S. aureus isolates harbored clfA, clfB, eno, fib, icaA, and icaD genes.
Topics: Anti-Bacterial Agents; Biofilms; Methicillin; Methicillin Resistance; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Polymerase Chain Reaction
PubMed: 26948126
DOI: 10.7508/ibj.2016.03.007 -
Poultry Science Oct 2022Colonization of food-producing animals by antimicrobial-resistant Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), has become a serious public...
Clonal distribution and antimicrobial resistance of methicillin-susceptible and -resistant Staphylococcus aureus strains isolated from broiler farms, slaughterhouses, and retail chicken meat.
Colonization of food-producing animals by antimicrobial-resistant Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), has become a serious public health problem worldwide. In the current study, clonal diversities of livestock-associated S. aureus isolates collected from broiler farms, slaughterhouses, and retail chicken meat were examined. Two-hundred S. aureus isolates (43 MRSA and 157 methicillin-susceptible S. aureus [MSSA] isolates) were analyzed to determine 1) the genotypes of the isolates (multilocus sequence, agr, and spa types), 2) the methicillin resistance phenotype and staphylococcal cassette chromosome mec (SCCmec) types, 3) the antimicrobial resistance profiles, and 4) the mutational changes in gyrA, gyrB, parC, and parE in fluoroquinolone-resistant isolates. Fifteen different sequence types (STs) of MSSA strains displaying a relatively high degree of genetic diversity were detected in broiler farms, slaughterhouses, and retail chicken meat. In contrast to MSSA, 2 dominant genetic lineages of MRSA (ST692-SCCmecV with t2249 spa type, and ST188-SCCmecIVa with spa type t189) were found in healthy broilers. The high prevalence of ST692 and ST188 in healthy broilers is associated with high levels of multiple antimicrobial-resistance phenotypes, particularly fluoroquinolone resistance. All fluoroquinolone-resistant isolates carried double point mutations in gyrA (S84L) and parC (S80F), regardless of STs or methicillin resistance. Notably, only the ST188 lineage carried an additional third mutation in gyrB (D494N), correlating with enhanced ciprofloxacin minimum inhibitory concentration values versus the strains with double mutations. These results provide important insights into the genetic diversity of antimicrobial-resistant S. aureus strains associated with the chicken meat production chain, including healthy broilers, in Korea.
Topics: Abattoirs; Animals; Anti-Bacterial Agents; Chickens; Ciprofloxacin; Drug Resistance, Bacterial; Farms; Fluoroquinolones; Genotype; Meat; Methicillin; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Staphylococcal Infections; Staphylococcus aureus
PubMed: 36041389
DOI: 10.1016/j.psj.2022.102070 -
Journal of Microbiology and... Dec 2022is a cause of high mortality in humans and therefore it is necessary to prevent its transmission and reduce infections. Our goals in this research were to investigate...
is a cause of high mortality in humans and therefore it is necessary to prevent its transmission and reduce infections. Our goals in this research were to investigate the frequency of methicillin-resistant (MRSA) in Taif, Saudi Arabia, and assess the relationship between the phenotypic antimicrobial sensitivity patterns and the genes responsible for resistance. In addition, we examined the antimicrobial efficiency and application of silver nanoparticles (AgNPs) against MRSA isolates. Seventy-two nasal swabs were taken from patients; MRSA was cultivated on Mannitol Salt Agar supplemented with methicillin, and 16S rRNA sequencing was conducted in addition to morphological and biochemical identification. Specific resistance genes such as , , , and were PCR-amplified and resistance plasmids were also investigated. The MRSA incidence was ~49 % among the 72 isolates and all MRSA strains were resistant to oxacillin, penicillin, and cefoxitin. However, vancomycin, linezolid, teicoplanin, mupirocin, and rifampicin were effective against 100% of MRSA strains. About 61% of MRSA strains exhibited multidrug resistance and were resistant to 3-12 antimicrobial medications (MDR). Methicillin resistance gene mecA was presented in all MDR-MRSA strains. Most MDR-MRSA contained a plasmid of > 10 kb. To overcome bacterial resistance, AgNPs were applied and displayed high antimicrobial activity and synergistic effect with penicillin. Our findings may help establish programs to control bacterial spread in communities as AgNPs appeared to exert a synergistic effect with penicillin to control bacterial resistance.
Topics: Humans; Methicillin-Resistant Staphylococcus aureus; Methicillin Resistance; Anti-Bacterial Agents; Staphylococcus aureus; Silver; Prevalence; Metal Nanoparticles; RNA, Ribosomal, 16S; Bacterial Proteins; Penicillin-Binding Proteins; Microbial Sensitivity Tests; Methicillin; Staphylococcal Infections
PubMed: 36379700
DOI: 10.4014/jmb.2208.08004 -
Antimicrobial Agents and Chemotherapy Dec 2023is the most prevalent cystic fibrosis (CF) pathogen. Several phenotypes are associated with worsened CF clinical outcomes including methicillin-resistance and...
is the most prevalent cystic fibrosis (CF) pathogen. Several phenotypes are associated with worsened CF clinical outcomes including methicillin-resistance and small-colony-variants. The inoculum effect (IE) is characterized by reduced β-lactam susceptibility when assessed at high inoculum. The IE associates with worse outcomes in bacteremia and other high-density infections, and may therefore be relevant to CF. The prevalence of IE amongst a CF cohort (age ≥18 years), followed from 2013 to 2016, was investigated. Yearly methicillin-sensitive (MSSA) isolates were screened at standard (5 × 10 CFU/mL) and high (5 × 10 CFU/mL) inoculum against narrow-spectrum anti-Staphylococcal β-lactams and those with anti-pseudomonal activity common to CF. A ≥ 4-fold increase in minimum inhibitory concentration between standard and high inoculum defined IE. Isolates underwent sequencing and genotyping and were compared against published genomes. Fifty-six percent (99/177) of individuals had MSSA infection. MSSA was observed at ≥10 CFU/mL in 44.8% of entry sputum samples. The prevalence of the IE was 25.0%-cefazolin; 13.5%-cloxacillin; 0%-meropenem; 1.0%-cefepime; 5.2%-ceftazidime; and 34.4%-piperacillin-tazobactam amongst baseline MSSA isolates assessed. A associated with cefazolin IE ( = 0.0011), whereas C associated with piperacillin-tazobactam IE ( < 0.0001). Baseline demographics did not reveal specific risk factors for IE-associated infections, nor were long-term outcomes different. Herein, we observed the IE in CF-derived MSSA disproportionally for cefazolin and piperacillin-tazobactam and this phenotype strongly associated with underlying genotype. The confirmation of CF being a high density infection, and the identification of high prevalence of MSSA with IE in CF supports the need for prospective pulmonary exacerbation treatment studies to understand the impact of this phenotype.
Topics: Adult; Humans; Adolescent; Methicillin; Cefazolin; Staphylococcus aureus; Anti-Bacterial Agents; Prospective Studies; Cystic Fibrosis; Staphylococcal Infections; Monobactams; Piperacillin, Tazobactam Drug Combination; Ceftazidime; beta Lactam Antibiotics; Microbial Sensitivity Tests
PubMed: 37966229
DOI: 10.1128/aac.00136-23 -
Scientific Reports Apr 2022Biofilm-associated infections are of great concern because they are associated with antibiotic resistance and immune evasion. Co-colonization by Staphylococcus aureus...
Biofilm-associated infections are of great concern because they are associated with antibiotic resistance and immune evasion. Co-colonization by Staphylococcus aureus and Streptococcus pneumoniae is possible and a threat in clinical practice. We investigated the interaction between S. aureus and S. pneumoniae in mixed biofilms and tested new antibiofilm therapies with antioxidants N-acetyl-L-cysteine (NAC) and cysteamine (Cys). We developed two in vitro S. aureus-S. pneumoniae mixed biofilms in 96-well polystyrene microtiter plates and we treated in vitro biofilms with Cys and NAC analyzing their effect by CV staining and viable plate counting. S. pneumoniae needed a higher proportion of cells in the inoculum and planktonic culture to reach a similar population rate in the mixed biofilm. We demonstrated the effect of Cys in preventing S. aureus biofilms and S. aureus-S. pneumoniae mixed biofilms. Moreover, administration of 5 mg/ml of NAC nearly eradicated the S. pneumoniae population and killed nearly 94% of MSSA cells and 99% of MRSA cells in the mixed biofilms. The methicillin resistance background did not change the antioxidants effect in S. aureus. These results identify NAC and Cys as promising repurposed drug candidates for the prevention and treatment of mixed biofilms by S. pneumoniae and S. aureus.
Topics: Acetylcysteine; Anti-Bacterial Agents; Antioxidants; Biofilms; Cysteamine; Methicillin; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Staphylococcus aureus; Streptococcus pneumoniae
PubMed: 35461321
DOI: 10.1038/s41598-022-10609-x -
Microbiology Spectrum Aug 2023Methicillin-resistant Staphylococcus aureus (MRSA) is a clinical threat with high morbidity and mortality. Here, we describe a new simple, rapid identification method...
Methicillin-resistant Staphylococcus aureus (MRSA) is a clinical threat with high morbidity and mortality. Here, we describe a new simple, rapid identification method for MRSA using oxacillin sodium salt, a cell wall synthesis inhibitor, combined with Gram staining and machine vision (MV) analysis. Gram staining classifies bacteria as positive (purple) or negative (pink) according to the cell wall structure and chemical composition. In the presence of oxacillin, the integrity of the cell wall for methicillin-susceptible S. aureus (MSSA) was destroyed immediately and appeared Gram negative. In contrast, MRSA was relatively stable and appeared Gram positive. This color change can be detected by MV. The feasibility of this method was demonstrated in 150 images of the staining results for 50 clinical S. aureus strains. Based on effective feature extraction and machine learning, the accuracies of the linear linear discriminant analysis (LDA) model and nonlinear artificial neural network (ANN) model for MRSA identification were 96.7% and 97.3%, respectively. Combined with MV analysis, this simple strategy improved the detection efficiency and significantly shortened the time needed to detect antibiotic resistance. The whole process can be completed within 1 h. Unlike the traditional antibiotic susceptibility test, overnight incubation is avoided. This new strategy could be used for other bacteria and represents a new rapid method for detection of clinical antibiotic resistance. Oxacillin sodium salt destroys the integrity of the cell wall of MSSA immediately, appearing Gram negative, whereas MRSA is relatively stable and still appears Gram positive. This color change can be detected by microscopic examination and MV analysis. This new strategy has significantly reduced the time to detect resistance. The results show that using oxacillin sodium salt combined with Gram staining and MV analysis is a new, simple and rapid method for identification of MRSA.
Topics: Humans; Methicillin-Resistant Staphylococcus aureus; Staphylococcus aureus; Microbial Sensitivity Tests; Oxacillin; Methicillin; Staining and Labeling; Anti-Bacterial Agents; Staphylococcal Infections
PubMed: 37395643
DOI: 10.1128/spectrum.05282-22