Molecular Characterization and Antimicrobial Susceptibility of Staphylococcus aureus Isolates from Clinical Infection and Asymptomatic Carriers in Southwest Nigeria
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Abstract
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Few reports from Africa suggest that resistance pattern, virulence factors and genotypes differ
between Staphylococcus aureus from nasal carriage and clinical infection.We therefore
compared antimicrobial resistance, selected virulence factors and genotypes of S. aureus
from nasal carriage and clinical infection in Southwest Nigeria. Non-duplicate S. aureus
isolates were obtained from infection (n = 217) and asymptomatic carriers (n = 73) during a
cross sectional study in Lagos and Ogun States, Nigeria from 2010–2011. Susceptibility
testing was performed using Vitek automated systems. Selected virulence factors were
detected by PCR. The population structure was assessed using spa typing. The spa clonal
complexes (spa-CC) were deduced using the Based Upon Repeat Pattern algorithm
(BURP). Resistance was higher for aminoglycosides in clinical isolates while resistances to
quinolones and tetracycline were more prevalent in carrier isolates. The Panton-Valentine
leukocidin (PVL) was more frequently detected in isolates from infection compared to carriage
(80.2 vs 53.4%; p < 0.001, chi2-test). Seven methicillin resistant S. aureus isolates
were associated with spa types t002, t008, t064, t194, t8439, t8440 and t8441. The predominant
spa types among the methicillin-susceptible S. aureus isolates were t084 (65.5%),
t2304 (4.4%) and t8435 (4.1%). spa-CC 084 was predominant among isolates from infection
(80.3%, n = 167) and was significantly associated with PVL (OR = 7.1, 95%CI: 3.9–
13.2, p < 0.001, chi2- test). In conclusion, PVL positive isolates were more frequently
detected among isolates from infection compared to carriage and are associated with
spa-CC 084.
Keywords
RM Therapeutics. Pharmacology