Phenotypic and genotypic characterization of oxacillin-susceptible and mecA positive Staphylococcus aureus strains isolated in Uruguay

Pardo, Lorena; Giudice, Guillermina; Mota, María Inés; Gutiérrez, C. P.; Varela, Adriana; Algorta, Gabriela; Seija, Verónica; Galiana, Antonio; Aguerrebere, Paula; Klein, Mónica; Varela, Gustavo

doi:10.1016/j.ram.2022.05.004

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…For instance, 3.6% of the cefoxitin-resistant S . aureus in this study were susceptible to oxacillin ( Table 3 ), consistent with previous findings which suggest that oxacillin is a less reliable predictor of MRSA [ 30 ]. Despite the high MDR prevalence among MRSA ( Table 3 ), the MRSA in this study were largely susceptible to non-β-lactam antibiotics.…”

Section: Discussionsupporting

confidence: 92%

Trends, patterns and relationship of antimicrobial use and resistance in bacterial isolates tested between 2015–2020 in a national referral hospital of Zambia

Shawa,

Paudel,

Chambaro

et al. 2024

PLoS ONE

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Increased antimicrobial resistance (AMR) among bacteria underscores the need to strengthen AMR surveillance and promote data-based prescribing. To evaluate trends and associations between antimicrobial usage (AMU) and AMR, we explored a dataset of 34,672 bacterial isolates collected between 2015 and 2020 from clinical samples at the University Teaching Hospital (UTH) in Lusaka, Zambia. The most frequently isolated species were Escherichia coli (4,986/34,672; 14.4%), Staphylococcus aureus (3,941/34,672; 11.4%), and Klebsiella pneumoniae (3,796/34,672; 10.9%). Of the 16 drugs (eight classes) tested, only amikacin and imipenem showed good (> 50%) antimicrobial activity against both E. coli and K. pneumoniae, while nitrofurantoin was effective only in E. coli. Furthermore, 38.8% (1,934/4,980) of E. coli and 52.4% (2,079/3,791) of K. pneumoniae isolates displayed multidrug resistance (MDR) patterns on antimicrobial susceptibility tests. Among S. aureus isolates, 44.6% (973/2,181) were classified as methicillin-resistant (MRSA). Notably, all the MRSA exhibited MDR patterns. The annual hospital AMR rates varied over time, while there was a weak positive relationship (r = 0.38, 95% CI = 0.11–0.60) between the monthly use of third-generation cephalosporins (3GCs) and 3GC resistance among Enterobacterales. Overall, the results revealed high AMR rates that fluctuated over time, with a weak positive relationship between 3GC use and resistance. To our knowledge, this is the first report to evaluate the association between AMU and AMR in Zambia. Our results highlight the need to strengthen antimicrobial stewardship programs and optimize AMU in hospital settings.

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Section: Discussionsupporting

confidence: 92%

Trends, patterns and relationship of antimicrobial use and resistance in bacterial isolates tested between 2015–2020 in a national referral hospital of Zambia

Shawa,

Paudel,

Chambaro

et al. 2024

PLoS ONE

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“…Oxacillin-susceptible MRSA (OS-MRSA) is susceptible to oxacillin (MICs≤2μg/mL) but mecA / mecC- positive. 47 Because OS-MRSA is sensitive to oxacillin, routine drug susceptibility tests are prone to misidentify MRSA, resulting in potential treatment failure. Therefore, the combination of drug resistance phenotype and PCR genotype is more appropriate to identify MRSA.…”

Section: Classification Of Mrsamentioning

confidence: 99%

Progress in the Prevalence, Classification and Drug Resistance Mechanisms of Methicillin-Resistant Staphylococcus aureus

Hou¹,

Liu²,

Wei³

et al. 2023

IDR

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Staphylococcus aureus is a common human pathogen with a variety of virulence factors, which can cause multiple infectious diseases. In recent decades, due to the constant evolution and the abuse of antibiotics, Staphylococcus aureus was becoming more resistant, the infection rate of MRSA remained high, and clinical treatment of MRSA became more difficult. The genetic diversity of MRSA was mainly represented by the continuous emergence of epidemic strains, resulting in the constant changes of epidemic clones. Different classes of MRSA resulted in different epidemics and resistance characteristics, which could affect the clinical symptoms and treatments. MRSA had also spread from traditional hospitals to community and livestock environments, and the new clones established a relationship between animals and humans, promoting further evolution of MRSA. Since the resistance mechanism of MRSA is very complex, it is important to clarify these resistance mechanisms at the molecular level for the treatment of infectious diseases. We firstly described the diversity of SCC mec elements, and discussed the types of SCC mec , its drug resistance mechanisms and expression regulations. Then, we described how the vanA operon makes Staphylococcus aureus resistant to vancomycin and its expression regulation. Finally, a brief introduction was given to the drug resistance mechanisms of biofilms and efflux pump systems. Analyzing the resistance mechanism of MRSA can help study new anti-infective drugs and alleviate the evolution of MRSA. At the end of the review, we summarized the treatment strategies for MRSA infection, including antibiotics, anti-biofilm agents and efflux pump inhibitors. To sum up, here we reviewed the epidemic characteristics of Staphylococcus aureus , summarized its classifications, drug resistance mechanisms of MRSA (SCC mec element, vanA operon, biofilm and active efflux pump system) and novel therapy strategies, so as to provide a theoretical basis for the treatment of MRSA infection.

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“…The mecA positive strain was not resistant to oxacillin, showing an MIC equal to the S. aureus ECOFF for this antibiotic. The occurrence of mecA positive and oxacillin sensitive strains was reported recently [29].…”

Section: Occurrence Of Ar Genes In the S Aureus Isolatesmentioning

confidence: 86%

Recent Trends of Antibiotic Resistance in <em>Staphylococcus aureus</em> Causing Clinical Mastitis in Dairy Herds in Abruzzo and Molise Regions, Italy

Rossi¹,

Matto²,

Saletti³

et al. 2023

Preprint

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This study was aimed to examine the recent trends of antibiotic resistance (AR) prevalence in Staphylococcus aureus isolated from milk of animals with clinical mastitis in areas of the Abruzzo and Molise regions in central Italy. Fifty-four S. aureus isolates could be obtained from routine testing for clinical mastitis agents carried out in the author institution in years 2021 and 2022. These were analyzed for phenotypic resistance to eight antibiotics recommended for testing by European norms and belonging to the antibiotic classes used for mastitis treatment in milk producing animals. Moreover, the presence of 14 transferable genetic determinants encoding resistance to the same antibiotics was analyzed by qPCR tests developed in this study. Phenotypic resistance to non-β-lactams was infrequent, with only one 2022 isolate resistant to clindamycin. However, low level resistance to the β-lactam cefoxitin was observed in 59.2% isolates in both years making these isolates classifiable as methicillin resistant. The AR genotypes detected were blaZ gene (50% 2021 isolates and 44.4% 2022 isolates), ermC/T- aphA3-blaZ (one 2021 isolate), ant6-ermC/T-aphA3-blaZ (one 2021 isolate), ermB-blaZ (one 2022 isolate) and mecA-mph (one 2022 isolate). An interview to the veterinarians who conferred the samples, regarding antimicrobials prescribed for mastitis treatment and criteria of usage, indicated a possible causal relation with the AR test results. The low prevalence of AR genotypes, not increasing in time, most probably reflecting the reported management of antibiotic therapies in farms. However, the frequently observed cefoxitin resistance needs to be explained genotypically, further monitored and limited by modifying antibiotic usage practices. The identification of a mecA positive isolate in 2022 suggests to investigate further if this genotype is emerging locally.

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Phenotypic and genotypic characterization of oxacillin-susceptible and mecA positive Staphylococcus aureus strains isolated in Uruguay

Cited by 6 publications

References 13 publications

Trends, patterns and relationship of antimicrobial use and resistance in bacterial isolates tested between 2015–2020 in a national referral hospital of Zambia

Trends, patterns and relationship of antimicrobial use and resistance in bacterial isolates tested between 2015–2020 in a national referral hospital of Zambia

Progress in the Prevalence, Classification and Drug Resistance Mechanisms of Methicillin-Resistant Staphylococcus aureus

Recent Trends of Antibiotic Resistance in <em>Staphylococcus aureus</em> Causing Clinical Mastitis in Dairy Herds in Abruzzo and Molise Regions, Italy

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