Virulence and Drug-Resistance of Staphylococcus aureus Strains Isolated from Venous Ulcers in Polish Patients

Mateusz Gajda,Monika Pomorska-Wesołowska,Dorota Romaniszyn,Emilia Załugowicz,Tomasz Bochenek,Barbara Gryglewska,Jadwiga Wójkowska-Mach,Agnieszka Chmielarczyk

doi:10.3390/ijerph18094662

Abstract

Infected chronic venous ulcers (VUs) represent a major health problem. We analysed the aerobic microbiome in the VUs, the virulence, and drug-resistance of Staphylococcus aureus (SA) strains. Swabs from 143 outpatients and inpatients Polish subjects were collected. SA strains were tested for drug sensitivity using a phenotyping method and for methicillin-resistant SA (MRSA) and macrolide-lincosamide-streptogramin B (MLSB) resistance using PCR. We analysed virulence genes, the genetic similarity of strains, and performed Staphylococcal cassette chromosome mec typing and Staphylococcal protein A typing. SA was isolated as a single one in 34.9% of cases, 31.5% paired with another pathogen, and 33.6% S. aureus combined with at least two other strains. The majority of SA isolates (68.5%) possessed the virulence lukE gene. Drug resistance was significantly common in hospitalised than in ambulatory patients (OR 3.8; 95%CI 1.8–7.91). MLSB (altogether in 19.6% isolates) were observed mostly in non-hospitalised patients (OR 9.1; 95%CI 1.17–71.02), while MRSA was detected in 11.9% of strains equally. Hospitalisation and patient’s age group (aged > 78.0 or < 54.5 years) were significant predictors of the multi-drug resistant SA (MDR-SA). Over 30% of the infected VUs were associated with multi-species biofilms and presence of potentially highly pathogenic microorganisms. Elderly hospitalised patients with chronic venous ulcers are prone to be infected with a MDR-SA.

Highlights

Venous ulceration (VU) of the lower extremity is an open sore in the lower leg’s skin, resulting from chronic venous insufficiency and high blood pressure in the leg veins [1]
In the microbiological diagnostics of the 143 patient samples, we identified 50 cases where Staphylococcus aureus was the single aetiological factor (34.9%), 45 cases (31.5%) in which it was accompanied by another factor, and 48 (33.6%) cases with three or more aetiological factors (Figure 1)
We identified the presence of 5 microbe species which we could not identify, and those were excluded from the analysis

Summary

Introduction

Venous ulceration (VU) of the lower extremity is an open sore in the lower leg’s skin, resulting from chronic venous insufficiency and high blood pressure in the leg veins [1]. The persistent venous hypertension causes retention of a high-protein fluid within tissues, which triggers an inflammatory process and activates the leucocytes. The resulting destruction of skin and subcutaneous tissue is observed as an ulceration. Leg ulcers have been most clearly defined by the WHO [2,3,4]. The prevalence of active leg ulcers is between 1.5 and 3.0 per 1000 population, but it rises with age to reach about 20 in people aged more than 80, as estimated on the British population. [5] Similar estimates have been made for the American adult population [6,7].

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