The Effects of Ceftriaxone and Ciprofloxacin Antibiotics Concentration levels on Staphylococcus aureus Growth and Resistance.

Author

Libelato, Nigel S.

Title

The Effects of Ceftriaxone and Ciprofloxacin Antibiotics Concentration levels on Staphylococcus aureus Growth and Resistance.

Abstract

The study investigated the effects of varying concentration levels of ceftriaxone and ciprofloxacin antibiotics on the growth and resistance development of Staphylococcus aureus isolates. The experiment was conducted using Methicillin Susceptible Staphylococcus aureus (MSSA) and as well as the Methicillin Resistant Staphylococcus aureus (MRSA) strains obtained from Bindura Provincial Hospital and Shashi Hospital. Antimicrobial activities were assessed by measuring the diameter of inhibition zones on Mueller Hinton agar using antibiotic-impregnated discs at low and high concentrations. Bacterial samples were then re-exposed to standard therapeutic doses to evaluate changes in susceptibility. Quantitative results showed that both antibiotics effectively inhibited S. aureus growth, with combination treatments exhibiting the greatest zones of inhibition. Higher concentrations significantly enhanced antibacterial efficacy compared to lower concentrations. Upon re-exposure, bacteria previously subjected to low concentrations exhibited reduced inhibition zones, indicating resistance development. Statistical analysis using one-way ANOVA and Tukey’s post hoc test confirmed significant differences among treatment groups (p < 0.001). The findings suggest that sub-lethal antibiotic exposure contributes to the emergence of resistance in S. aureus, while combination therapy and appropriate dosing improve treatment effectiveness. The study highlights the clinical importance of antibiotic stewardship in minimizing resistance and supports further research into combination therapies and resistance mechanisms.

Date

June 2025

Publisher

BUSE

Keywords

Ceftriaxone

Ciprofloxacin

Staphylococcus Aureus

Antibiotics Concentration

Supervisor

Dr. P. Manyanga