# Hemolytic activity and antibiotic resistance profiles of Staphylococcus aureus isolates from clinical patients

## TL;DR

This study examines the hemolytic activity and antibiotic resistance of Staphylococcus aureus in dialysis patients and others, revealing patterns that could improve treatment strategies.

## Contribution

The study identifies distinct hemolysin gene and antibiotic resistance profiles in S. aureus isolates from vascular access and non-vascular access infections.

## Key findings

- MRSA and MSSA isolates showed β- and γ-hemolytic phenotypes with hla and hld being the most common hemolysin genes.
- Over 80% of isolates were ampicillin-resistant, with higher multidrug resistance in MRSA.
- No significant differences were found in resistance patterns between vascular and non-vascular access isolates.

## Abstract

Staphylococcus aureus is a common human pathogen that can cause vascular and skin infections, and patients undergoing hemodialysis are particularly susceptible to vascular access infections caused by S. aureus. Hemolysins are important virulence factors, and antibiotic resistance poses challenges for treatment. In this study, S. aureus isolates were collected from hemodialysis patients with vascular access, such as arteriovenous grafts, tunneled-cuffed catheters, and arteriovenous fistulas, as well as from non-vascular access infection (VAI) patients. The hemolytic phenotype and eight antibiotic susceptibility of these isolates were tested, and PCR was used to detect hemolysin (hla, hlb, hld, and hlgC/B) and antibiotic resistance genes (accA-aphD, tetM, and tetK). The results showed that methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) isolates exhibited only β- and γ-hemolytic phenotypes. The hla and hld genes were the most frequently detected hemolysin genes, whereas hlb was the least common. Over 80% of both MRSA and MSSA isolates exhibited resistance to ampicillin, with multidrug resistance observed more frequently in MRSA. Distinct antibiotic resistance gene patterns were observed in MRSA and MSSA isolates. Despite these differences in gene patterns, no obvious differences were found between VAI and non-VAI patients, or between MRSA and MSSA isolates. These findings provide a better understanding of the hemolytic characteristics and antibiotic susceptibility of S. aureus isolates collected from hemodialysis and non-hemodialysis patients, contributing to more targeted and effective treatment strategies.

Staphylococcus aureus is a common human pathogen, and dialysis patients are at higher risk of infection compared to the general population because this bacterium can colonize medical devices and vascular access catheters. Among its various virulence factors, hemolysins play a crucial role by damaging host cells and helping the bacteria evade immune defenses. The widespread use of antibiotics has led to the emergence of antibiotic-resistant S. aureus, especially methicillin-resistant S. aureus, further complicating treatment. This study aims to investigate the types of hemolysins, the distribution of hemolysin and antibiotic resistance genes, and antibiotic resistance patterns in S. aureus isolates from patients with vascular access-related and non-vascular access infections, providing a reference for infection control and treatment strategies.