Methicillin-Resistant Staphylococcus aureus from Peninsular Malaysian Animal Handlers: Molecular Profile, Antimicrobial Resistance, Immune Evasion Cluster and Genotypic Categorization

Staphylococcus aureus (S. aureus) infections, particularly methicillin-resistant Staphylococcus aureus (MRSA) in humans and animals, have become a significant concern globally. The present study aimed to determine the prevalence and antibiogram of S. aureus isolated from animal handlers in Peninsular Malaysia. Furthermore, the genotypic characteristics of S. aureus isolates were also investigated. Nasal and oral swab samples were collected from 423 animal handlers in Peninsular Malaysia. The antibiogram profiles of S. aureus against 18 antibiotics were established using a Kirby–Bauer test. The genotypic profile of S. aureus, including the presence of antimicrobial resistance (AMR), virulence genes and spa genotypes, was investigated using molecular techniques. The overall carriage rate of S. aureus, MRSA and MDRSA was 30.5%, 1.2% and 19.4%, respectively. S. aureus was highly resistant against penicillin (72.3%) and amoxicillin (52.3%). Meanwhile, gentamicin and linezolid were fully effective against all the isolated S. aureus from animal handlers. It was observed that animal handlers with close exposure to poultry were more likely to carry S. aureus that is resistant to tetracycline and erythromycin. S. aureus isolates harboured tetracycline resistance (tetK, tetL and tetM), erythromycin resistance (ermA, ermB, ermC and msrA) and immune evasion cluster (IEC) genes (scn, chp, sak, sea and sep). Seventeen different spa types were detected among the 30 isolates of MDRSA, with t189 (16.7%) and t4171 (16.7%) being the predominant spa type, suggesting wide genetic diversity of the MDRSA isolates. The present study demonstrated the prevalence of S. aureus strains, including MRSA and MDRSA with various antimicrobial resistance and genetic profiles from animal handlers in Peninsular Malaysia.

Validation of Vancomycin Area under the Concentration—Time Curve Estimation by the Bayesian Approach Using One-Point Samples for Predicting Clinical Outcomes in Patients with Methicillin-Resistant Staphylococcus aureus Infections

Area under the concentration–time curve (AUC)-guided vancomycin treatment is associated with decreased nephrotoxicity. It is preferable to obtain two samples to estimate the AUC. This study examined the usefulness of AUC estimation via trough concentration (Cmin)-only sampling of 260 adults infected with methicillin-resistant Staphylococcus aureus (MRSA) who received vancomycin. The exact Cmin sampling time was used for Bayesian estimation. A significantly higher early treatment response was observed in patients with a day 2 AUC ≥ 400 µg·h/mL than those with <400 µg·h/mL, and a significantly higher early nephrotoxicity rate was observed in patients with a day 2 AUC ≥ 600 µg·h/mL than those with <600 µg·h/mL. These AUC cutoff values constituted independent factors for each outcome. In sub-analysis, the discrimination ability for early clinical outcomes using these AUC cutoffs was confirmed only in patients with q12 vancomycin administration. A significant difference in early treatment response using the 400 µg·h/mL cutoff was obtained only in patients with low-risk infections. The usefulness of the vancomycin AUC target to decrease nephrotoxicity while assuring clinical efficacy was even confirmed with a single Cmin measurement. However, assessment with two samples might be required in patients with q24 administration or high/moderate-risk MRSA infections.

Antistaphylococcal effects of alcoholic extracts of Tetrapleura tetraptera (Schum and Thonn.) (Taub.) against multidrug methicillin resistant Staphylococcus aureus

Background: Staphylococcus aureus is a pathogen causing life-threatening hospital and community-acquired infections with high morbidity and mortality rates requiring constant vigilance.Aim: This study aimed at investigating the antistaphylococcal effects of Tetrapleura tetraptera against different strains of multidrug methicillin resistant S. aureus (MRSA) to indicate the need for its use in ethnomedicine in addition to its fruits being used in traditional medicine.Methods: In this study, the susceptibilities of S. aureus were investigated using multi-disc antibiotics and extracts of T. tetraptera by agar diffusion and macrobroth dilution methods.Settings: While attention has been focused on the fruits of this plant, it is necessary to investigate the pharmacological importance of its stem bark.Results: The antibiogram showed that 70% of the isolates were multidrug resistant. Nitrofurantoin and gentamicin antibiotics were the most effective whilst amoxicillin and augumentin were the least effective. The susceptibility of the isolates was concentration dependent as inhibition zones decreased with decrease in the concentrations of each of the extracts. The minimum inhibitory concentrations (MICs) of acetone extract ranged between 0.019 mg/mL and 20 mg/mL whilst the minimum bactericidal concentrations (MBCs) ranged between 0.3125 mg/mL and 20 mg/mL. The MICs of the methanol extract ranged between 0.039 mg/mL and 5.0 mg/mL whilst the MBCs ranged between 0.3125 mg/mL and 10 mg/mL. Both extracts were more bactericidal than being bacteriostatic against all the isolates. The methanol extract was more active than the acetone extract as indicated by the varied inhibition zones and MICs obtained from the different extracts.Conclusion: This study revealed the great therapeutic potentials of T. tetraptera and validated its use in ethnomedicine and would be effective in the treatment of multidrug and MRSA infections.

The Antimicrobial Activity of Pechuel-Loeschea leubnitziae Leaf Extract and its Effect on The Expression Level of Methicillin Resistant Staphylococcus Aureus and Candida albicans Virulence-Associated Genes

The complete halt in the synthesis of new effective antimicrobial compounds is a global concern. Pathogenic microorganisms' virulence mechanisms seem to have a significant impact on their pathogenesis. The purpose of this study was to examine the antimicrobial activity of the ethanol and methanol fractions of Pechuel-Loeschea leubnitziae leaf extract, as well as its effect on the expression level of virulence-associated genes.The extract's fractions were evaluated for antimicrobial activity against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae (clinical), Methicillin-resistant Staphylococcus aureus, and Candida albicans ATCC 90029. The test organism's antibiogram pattern was determined. The extracts' attenuation effect on the target genes of the susceptible organisms was investigated employing relative quantification using RT-qPCR. The test organism's antibiogram pattern revealed that it was drug-resistant, intermediate, and sensitive. The extracts tested positive for antimicrobial activity against Methicillin-resistant Staphylococcus aureus and Candida albicans ATCC 90029, with zones of inhibition varying from 20.33 to 29 mm. The lowest recorded MIC value was 4.688 mg/ml, while the highest was 37.5 mg/ml. In contrast to the methanol extract, the ethanol extract had a cidal action at a lower dose. The ethanol extract's Sub-MIC (18.25 mg/ml) merely reduced the expression of the hly gene in MRSA. The MRSA virulence genes were not suppressed by the sub-MIC of methanol extract (18.25 mg/ml). Notably, the expression of als1, pbl1, and sap1 in Candida albicans ATCC 90029 was significantly attenuated when exposed to sub-MICs of ethanol extract (2,344 mg/ml) and methanol extract (9.375 mg/ml). Per the findings of this research, the leaves of P. leubnitziae could be a source of an effective antimicrobial agent in the therapy of MRSA/Candida-related disorders.