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Molecular epidemiology and study of virulence factors of Staphylococcus aureus resistant to oxacillin isolated from wounds in patients treated in basic health units in the city of Botucatu

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Eliane Patricia Lino Pereira Franchi
Total Authors: 1
Document type: Doctoral Thesis
Press: Botucatu. 2016-03-18.
Institution: Universidade Estadual Paulista (Unesp). Faculdade de Medicina. Botucatu
Defense date:
Advisor: Maria de Lourdes Ribeiro de Souza da Cunha

Given the importance of methicillin resistant S. aureus (Methicillin-resistant Staphylococcus aureus - MRSA) and wounds, this study aimed to study the prevalence, risk factors and molecular epidemiology related to the presence of S. aureus sensitive and resistant to methicillin in wounds of patients who attended BHUs in a city in Sao Paulo state, Brazil. After the identification of S. aureus isolates was performed: susceptibility testing to 13 antimicrobial drugs, identification of the resistance gene (mecA) and the genes encoding Panton-Valentine Leukocidin - PVL (pvl), enterotoxins AE (sea , seb, sec, sed and see) hemolysins α, β and δ (hla, hlb and hld), esfoliatinas A, B and D (eta, etb and etd), biofilm (icaAD) and Toxin-1 syndrome of toxic shock - TSST-1 (tst); Molecular typing by Pulsed-Field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and spa typing. 171 patients were included and 119 S. aureus isolates. Nasal samples were collected only in 74 patients of the total sample. The prevalence of S. aureus and MRSA was 51.5% and 8.7%, respectively. Overall 101 MSSA were isolated from 73 patients, 98 of these were isolated from wounds and 21 nostrils; MRSA and 18 of 15 patients, 4 isolates from nostrils and 14 wounds, with six MRSA with SCCmec type II and 12 SCCmec type IV. The strains showed high-level resistance to penicillin (85%) followed by erythromycin (27%), gentamicin (12%), clindamycin (11%) and levofloxacin (6%). There was no resistance to sulfamethoxazole / trimethoprim, fusidic acid, tigecycline, quinupristin / dalfopristin and linezolid. The search for virulence genes in the 119 isolates of S. aureus sensitive and resistant, 42% demonstrated presence of genes sea, 11% to seb, 26% to sec , 0.8% to sed, 100% to icaA, 95.8% icaD, 97.5% to hla, 65% to hlb, 95% to hld, 4.2% to tst and 2.5% to pvl. There was an association between the presence of S. aureus in the nostrils to the wounds (p<0.01), the same was true for MRSA (p<0.01). Multivariate analysis for S. aureus, showed a negative association with age (OR: 0.94, 95% CI: 0.90-0.98, p<0.01), use of amoxicillin (OR: 0.16, 95% CI: 0.04-0.60, p<0.01) and ciprofloxacin (OR: 0.28, 95% CI: 0.08-0.98, p=0.04). On the other hand, there was a positive association with use of penicillin G (OR: 3.81, 95% CI: 1.23-11.82, p=0.02). There was the formation of eight clusters, with a predominance of MSSA presenting the STs: 5, 30, 188, 1635 and spa t002. The 18 MRSA were characterized by STs 5, 8 and spas 1176 and the t002, t008 and t062. Strains were isolated similar to international clones USA300, USA500 and USA800. Our results demonstrate the presence of important clones resistant and virulent MRSA patients studied in different UBS. (AU)

FAPESP's process: 12/00257-9 - Molecular epidemiology and study of virulence factors of Staphylococcus aureus resistant to oxacillin isolated from wounds in patients treated at Basic Health Units in the city of Botucatu
Grantee:Eliane Patricia Lino Pereira Franchi
Support type: Scholarships in Brazil - Doctorate