Abstract

MENDOZA TICONA, Carlos Alberto et al. Susceptibilidad antimicrobiana de Staphylococcus aureus sensible, con sensibilidad "BORDERLINE" y resistentes a la meticilina. Rev Med Hered [online]. 2003, vol.14, n.4, pp.181-185. ISSN 1018-130X.

Objective: To determine the susceptibility to different antibacterials of three categories of S. aureus according to its susceptibility to methicillin. Methods: 76 S. aureus strains that colonized patients and health workers were isolated from three Departments at Hospital Honorio Delgado in Arequipa, 36 of which were susceptible to methicillin (MSSA), 15 had borderline susceptibility (BORSA) and 25 where resistant to methicillin (MRSA). They underwent antibiogram for 14 antibacterials. Results: The only antibiotic to which all isolates were susceptible was vancomycin. MRSA were resistant to all betalactamics except imipenem that obtained 64% susceptibility. BORSA keep an 80% susceptibility to cephalotin and 100% to imipenem. The antibiotics cephalotin, imipenem, ciprofloxacine, cotrimoxazole, rifampicine, erithromycin, tetracycline, cloramphenicol, lincomycin and gentamycin had variable susceptibilities (p<0.01) among the three categories, a bigger proportion of MSSA were susceptible to these antibiotics, less for BORSA and lesser for MSSA. The multiresistant strains were more frequent in MRSA that in the other groups (p < 0.01). Conclusions: There are S. aureus strains in our environment with borderline susceptibility to methicillin. There are differences in the susceptibility to any antibacterials among the three groups of S. aureus; this differences can lead to a more rational antibacterial therapy. We should apply international recommendations for methicillin resistance detection in every strain isolation. : To determine the susceptibility to different antibacterials of three categories of S. aureus according to its susceptibility to methicillin. Methods: 76 S. aureus strains that colonized patients and health workers were isolated from three Departments at Hospital Honorio Delgado in Arequipa, 36 of which were susceptible to methicillin (MSSA), 15 had borderline susceptibility (BORSA) and 25 where resistant to methicillin (MRSA). They underwent antibiogram for 14 antibacterials. Results: The only antibiotic to which all isolates were susceptible was vancomycin. MRSA were resistant to all betalactamics except imipenem that obtained 64% susceptibility. BORSA keep an 80% susceptibility to cephalotin and 100% to imipenem. The antibiotics cephalotin, imipenem, ciprofloxacine, cotrimoxazole, rifampicine, erithromycin, tetracycline, cloramphenicol, lincomycin and gentamycin had variable susceptibilities (p<0.01) among the three categories, a bigger proportion of MSSA were susceptible to these antibiotics, less for BORSA and lesser for MSSA. The multiresistant strains were more frequent in MRSA that in the other groups (p < 0.01). Conclusions: There are S. aureus strains in our environment with borderline susceptibility to methicillin. There are differences in the susceptibility to any antibacterials among the three groups of S. aureus; this differences can lead to a more rational antibacterial therapy. We should apply international recommendations for methicillin resistance detection in every strain isolation.

Keywords : Staphylococcus aureus; methicillin resistance; borderline susceptibility; antibacterial susceptibility.

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