Susceptibility of Staphylococcus species and subspecies to teicoplanin

Abstract

Twenty-four Staphylococcus species and their subspecies were examined for their susceptibilities to teicoplanin by disk diffusion (30-,ug disk) and agar dilution for the determination of MICs. Moderately susceptible and resistant clinical strains were further tested for their susceptibilities to oxacillin and vancomycin. Teicoplanin resistance was not observed in the reference strains of the various Staphylococcus species isolated from healthy volunteers or animals. However, the novobiocin-resistant species Staphylococcus saprophyticus, Staphylococcus cohnii, Staphylococcus xylosus, Staphylococcus arlettae, Staphylococcus kloosii, and Staphylococcus gallinarum were less susceptible to teicoplanin (MIC, 2 to 8 ,ug/ml) than most of the novobiocin-susceptible species were (MIC, 0.5 to 4 ,Ig/ml). Clinical isolates of coagulase-negative species were generally less susceptible to teicoplanin than were reference strains. Seven percent of the Staphylococcus epidermidis clinical strains were moderately susceptible (MIC,16 ,u.g/ml) to teicoplanin. Of these strains, 70% were oxacillin resistant. For Staphylococcus haemolyticus strains, 11% were resistant (MIC, >16 ,ug/ml) and 21% were moderately susceptible to teicoplanin. Of these strains, 95% were oxacillin resistant. No strains of S. epidermidis or S. haemolyticus were intermediate or resistant to vancomycin. Teicoplanin appears to be less active in vitro against oxacillin-resistant S. haemolyticus. However, teicoplanin is an effective antimicrobial agent against many Staphylococcus species.The frequent isolation of clinically significant Staphylococcus species is a major concern for the medical community. In the past, patients were commonly treated with various penicillins, erythromycin, clindamycin, and/or gentamicin for staphylococcal infections. However, owing to many factors, including the extensive use of these antibiotics, staphylococci have developed resistant populations (17). For this reason, new antibiotics are being developed and tested on Staphylococcus species.Teicoplanin is a glycopeptide that targets the peptidoglycan synthesis of gram-positive bacteria (8,15). It is considered by some to be a drug of choice for the treatment of severe infections caused by antibiotic-resistant, gram-positive bacteria, especially the coagulase-negative staphylococci which often produce infections that are difficult to manage.In this study, 24 Staphylococcus species and 4 subspecies were tested for their susceptibilities to teicoplanin by disk diffusion and agar dilution for the determination of MICs. The moderately susceptible and resistant clinical strains were tested further for their susceptibilities to oxacillin and vancomycin.(A preliminary report of this work was presented previously [2].)Reference strains of the 24 Staphylococcus species and their subspecies were obtained from our laboratory's collection of isolates from the skin of healthy human volunteers or animals. The clinical strains used in this study were isolated from a variety of patients at Rex Hospit...

Update on clinical significance of coagulase-negative staphylococci

“…One possible approach that has received little attention and needs more research is the use of imipenem disks to determine vancomycin-resistant subpopulations. Schwalbe et al (277) found that S. haemolyticus strains selected by their growth on brain heart infusion agar containing 12 Decreased susceptibility of strains of S. haemolyticus and S. epidermidis to another glycopeptide, teicoplanin, has been more prevalent than that found with vancomycin (20,109,161,197). When determining the breakpoints of resistance and susceptibility, several groups have expressed concern over their inability to correlate results (47,119,197).…”

Antimicrobial susceptibility of coagulase-negative staphylococci

“…In contrast, 78% of selected S. epidermidis isolates from Hungary, Spain, and Switzerland were trimethoprim resistant, but the majority (70%) of these isolates were methicillin susceptible (19 ,ug/ml) in one study (14). Both vancomycin and teicoplanin resistance can be easily selected in vitro in S. haemolyticus by exposure of isolates to either vancomycin or teicoplanin (56,65), yet only teicoplanin resistance can be generated for S. epidermidis by stepwise exposure of this species to glycopeptides (17).…”

Staphylococcus haemolyticus – an emerging threat in the twilight of the antibiotics age

“…It was suggested that S. haemolyticus is unique amongst CNS and especially predisposed to resistance to glycopeptides, because of its extraordinary genome plasticity and tendency to frequent DNA rearrangements (Takeuchi et al, 2005). According to various studies, the percentage of hospital-isolated S. haemolyticus strains with reduced susceptibility to teicoplanin is increasing (Bannerman et al, 1991;Cercenado et al, 1996;Goldstein et al, 1990). What is alarming is that the strains were also isolated from infants in neonatal intensive care units (Pereira et al, 2014).…”