Reduced Susceptibility to Chlorhexidine among Staphylococcus aureus Isolates in Israel: Phenotypic and Genotypic Tolerance.

Maya Azrad,Keren Agay-Shay,Tamar Leshem,Moti Baum,Avi Peretz,Zohar Hamo,Assaf Rokney,Chen Shmuel

doi:10.3390/antibiotics10030342

Maya Azrad, Keren Agay-Shay + Show 6 more

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https://doi.org/10.3390/antibiotics10030342

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Abstract

Antiseptic use for body decolonization is the main activity applied to prevent healthcare-associated infections, including those caused by S. aureus. Consequentially, tolerance to several antiseptics such as chlorhexidine gluconate (CHG) has developed. This study aimed to estimate the prevalence of CHG tolerance among S. aureus strains in Israel and to evaluate factors that may affect this tolerance. Furthermore, it tested the associations between phenotypic and genotypic CHG tolerance. S. aureus strains (n = 190) were isolated from clinical samples of patients admitted to various medical institutions in Israel. Phenotypic susceptibility to CHG was assessed by determining minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Genotypic tolerance was detected using real-time PCR for detection of qac A/B genes. MIC for the antibiotic mupirocin was determined using the Etest method. Presence of the Panton–Valentine Leucocidin (pvl) toxin, mecA and mecC genes was detected using an eazyplex® MRSAplus kit (AmplexDiagnostics GmbH, Gars, Germany). CHG tolerance was observed in 13.15% of the isolates. An association between phenotypic and genotypic tolerance to CHG was observed. Phenotypic tolerance to CHG was associated with methicillin resistance but not with mupirocin resistance. Additionally, most of the CHG-tolerant strains were isolated from blood cultures. In conclusion, this work shed light on the prevalence of reduced susceptibility to CHG among S. aureus strains in Israel and on the characteristics of tolerant strains. CHG-tolerant strains were more common than methicillin-resistant ones in samples from invasive infections. Further research should be performed to evaluate risk factors for the development of CHG tolerance.

Highlights

Staphylococcus aureus (S. aureus) is one of the most common causes of human diseases, ranging from skin and soft tissue infections to pneumonia, meningitis, and sepsis [1]
This study included 92 methicillin-resistant S. aureus (MRSA) and 98 methicillin-sensitive S. aureus (MSSA) isolates recovered from blood cultures (35.3% isolates) and wound cultures (64.7% isolates) (Table 1)
The rates of phenotypic tolerance to chlorhexidine gluconate (CHG) vary between countries, ranging from

Summary

Introduction

Staphylococcus aureus (S. aureus) is one of the most common causes of human diseases, ranging from skin and soft tissue infections to pneumonia, meningitis, and sepsis [1]. One of the main preventive activities against healthcare-associated infections is the use of antiseptics and biocides for hand and body decolonization [5] in order to reduce the bacterial load of pathogens from the colonized or infected body [6] One example of such an antiseptic agent is chlorhexidine gluconate (CHG). Chlorhexidine (1,6-bis(4chlorophenylbiguanido)hexane) is active against a wide range of fungi, some viruses [7,8,9,10], and gram-positive and gram-negative bacteria, especially MRSA and vancomycin-resistant enterococci [11]. It is extensively utilized because of its long-lasting bactericidal effect and its satisfactory tolerability and safety profiles [6]

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