Related Experiment Video
Updated: May 1, 2026
09:26
Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung
Published on: January 22, 2021
7.7K
Fluoroquinolone Therapy in Staphylococcus aureus Infections: Where Do We Stand?
Neeta D Gade1, Mohiuddin S Qazi1
1Department of Microbiology, Government Medical College, Nagpur, Maharashtra, India.
Journal of Laboratory Physicians
|April 5, 2014
Summary
Fluoroquinolone resistance is high in Staphylococcus aureus, with ciprofloxacin ineffective against MRSA. Vancomycin remains the preferred treatment for MRSA infections.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Staphylococcus aureus is a significant human pathogen.
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a growing public health threat.
- Evaluating antimicrobial susceptibility is crucial for effective treatment.
Purpose of the Study:
- To assess the effectiveness of commonly used fluoroquinolones against Staphylococcus aureus isolates.
- To determine the prevalence of MRSA in clinical specimens.
- To identify optimal therapeutic agents for MRSA infections.
Main Methods:
- Susceptibility testing of 250 S. aureus isolates using Kirby-Bauer disc diffusion.
- MRSA detection via cefoxitin disk diffusion.
- Vancomycin Minimum Inhibitory Concentration (MIC) determination using E-test for MRSA strains.
- Phage typing of MRSA isolates.
Main Results:
- 42.8% of S. aureus isolates were identified as MRSA.
- High resistance rates to ciprofloxacin (92.5%) and ofloxacin (80.4%) were observed in MRSA.
- No resistance to vancomycin or linezolid was detected in any S. aureus isolates.
- Vancomycin MICs for MRSA ranged from 0.5 to 2 μg/ml.
Conclusions:
- Ciprofloxacin is no longer suitable for empirical treatment of MRSA infections.
- Fluoroquinolone use for MRSA should be guided by susceptibility testing.
- Vancomycin is the recommended treatment for MRSA infections.
Related Concept Videos
01:28Inhibitors of Bacterial DNA Synthesis
130
Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These...
130
01:25Clinical Significance of Antibiotic Resistance
90
Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist β-lactam antibiotics due to acquisition of the mecA gene within the staphylococcal cassette chromosome mec (SCCmec). This gene encodes penicillin-binding protein 2a (PBP2a), which impairs binding efficacy of methicillin and other β-lactams. MRSA has evolved into distinct clonal lineages impacting humans and animals alike, reinforcing its significance within...
90
01:25Mechanism of Antibiotic Resistance in MRSA
219
Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and...
219
01:28Gene Regulation in Microbial Communities: Quorum Sensing
954
Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
954
01:30Urinary Tract Infection III: Diagnostic Studies and Interprofessional Care
434
A healthcare provider can diagnose a urinary tract infection (UTI) through several methods:Medical History and Symptoms: The provider will take a detailed medical history and ask about symptoms such as frequent urination, burning sensation during urination, and lower abdominal pain.Urinalysis: A clean-catch urine sample is collected in a sterile container and tested for the presence of bacteria, white blood cells (leukocytes), nitrites, blood, and protein. The presence of leukocytes and...
434
01:28Acute Pyelonephritis II: Diagnostic Studies and Management
842
Introduction:For diagnosing acute pyelonephritis, a comprehensive patient history is collected to identify symptoms such as dysuria, frequent or urgent urination, flank pain, or costovertebral angle (CVA) tenderness that may suggest a kidney infection.Physical ExaminationDuring the physical examination, CVA tenderness is assessed. This involves gentle percussion over the costovertebral angle, where tenderness often indicates a kidney infection.Diagnostic TestsUrinalysis: Used to identify white...
842