Characterization of fusidic acid-resistant Staphylococcus aureus isolates in the community of Casablanca (Morocco).

Resistance to fusidic acid in Staphylococcus aureus is caused by mutation of the elongation factor G (EF-G) encoded by fusA or by expression of a protein, encoded by fusB or fusC, that protects the drug target. Other mechanisms involved in this resistance are mutations in the riboprotein L6 operon within rplF. The aim of this study was to determine the prevalence and mechanisms of resistance to fusidic acid in clinical isolates of S. aureus in Casablanca (Morocco) and to define the phenotypic and genotypic traits of these isolates and their clonal relationship. All fusidic acid-resistant S. aureus (FAR-SA) isolates were tested for fusB and fusC genes and were evaluated for the detection of mutations in fusA and fusE (rplF). fusB-positive strains were tested for a cadDX operon, encoding cadmium resistance. The agr group and the presence of toxin genes were monitored to characterize all FAR-SA isolates which were typed by pulsed-field gel electrophoresis (PFGE) and spa typing. Among 140 clinical S. aureus isolates collected in 2007 and 2008, 18 (∼13%) exhibited resistance to fusidic acid. The most common resistance determinant was fusC, found in 16 isolates. Molecular typing showed that 14 of them harboured an agr group III and belonged to the same clonal complex (CC) spa type 127 and identical clonotype (cluster labelled A). These isolates also possessed the staphylococcal enterotoxin H gene. The second resistance determinant was fusB found in two isolates. These two isolates lacked cadDX gene and were found to belong to two unrelated clusters and spa types. While no isolate carrying mutations in rplF was found, 15 expressed a silent mutation in fusA (nucleotide 342). Only acquired fusidic acid resistance genes (mainly fusC) were prevalent among FAR-SA isolates with almost all of the clinical specimens belonging to CC-spa type 127. This study provides valuable data on the prevalence of fusidic acid-resistant S. aureus with the associated molecular mechanisms of resistance and the genetic background of the strains in Casablanca.

Staphylococcus aureus nasal carriage in hemodialysis centers of Fez, Morocco.

BACKGROUND AND OBJECTIVES: Staphylococcus aureus (S. aureus) nasal carriage may be responsible for some serious infections in hemodialyzed patients. The main target of this study was to estimate the prevalence of S. aureus nasal carriage in hemodialysis outpatients and medical staff in hemodialysis centers specifically in Fez region. The second target is to identify the risks of colonization, resistance pattern of isolates and their virulence toxin genes. PATIENTS AND METHODS: Nasal swab specimens were obtained from 143 hemodialyzed outpatients and 32 medical staff from January to June 2012. Each participant completed a short questionnaire. Nasal carriage of S. aureus was demographically related (age, gender, hemodialysis duration), comorbidity (diabetes, malignancy) and exposure to health care (dialysis staff, hospitalization). PCR (Polymerase Chain Reaction) were used on all the isolates in the research of twelve staphylococcal enterotoxins genes. Also the PCR was used to investigate on the three factors epidermal cell differentiation inhibitors; three exfoliatin toxins; two leukotoxins; the toxic shock syndrome toxin-1 and the hemolysin beta genes. RESULTS: Nasal screening revealed 38.16%, 50% and 18.75% S. aureus carries in chronic, acute hemodialysis patients and medical staff, respectively. Only young participants were likely to be S. aureus carries (p = 0.002). But there were no gender differences between the isolate carriers and non-carriers or some comorbidity factors such as viral hepatitis B and C, HIV (Human Immunodeficiency Virus) infections, diabetes, chronic smoking, recent hospitalization or antibiotic therapy. Out of all isolates, only one (1.61%) was methicillin-resistant and Twenty-one (33.87%) had at least two virulence toxin genes. CONCLUSIONS: Knowledge and monitoring of antibiotic resistance profile and virulence of S. aureus carriage are essential in the treatment of infections generated by this pathogen, as well as in the control of clonal dissemination and prevent the spread of S. aureus resistance.