Activity of oxacillin versus that of vancomycin against oxacillin-susceptible mecA-positive Staphylococcus aureus clinical isolates evaluated by population analyses, time-kill assays, and a murine thigh infection model.

We compared the activity of dicloxacillin with that of vancomycin against 15 oxacillin-susceptible, methicillin-resistant Staphylococcus aureus (OS-MRSA) clinical isolates. By population analyses, we found that 6 OS-MRSA isolates were able to grow in the presence of up to 8 µg/ml dicloxacillin and 9 isolates were able to grow in 12 to >32 µg/ml dicloxacillin; all isolates grew in up to 2 µg/ml vancomycin. Both drugs exhibited similar bactericidal activities. In experimental infections, the therapeutic efficacy of dicloxacillin was significant (P < 0.05 versus untreated controls) in 10 OS-MRSA isolates and vancomycin was effective (P < 0.05) against 12 isolates; dicloxacillin had an efficacy that was comparable to that of vancomycin (P > 0.05) in 8 isolates. The favorable response to dicloxacillin treatment might suggest that antistaphylococcal penicillins could be used against OS-MRSA infections.

Chlamydia trachomatis serovar distribution and Neisseria gonorrhoeae coinfection in male patients with urethritis in Greece.

The distribution of Chlamydia trachomatis serovars and Neisseria gonorrhoeae coinfection was studied in a group of 100 C. trachomatis-positive males with urethritis in Greece. The serovar distribution revealed that apart from the predominant worldwide types E and F, the relatively uncommon type G is also prevalent. Gonococcal coinfection was frequent (30%) and was associated with genovariant Ja (75%, P = 0.008).

In vitro activity of tigecycline against 2423 clinical isolates and comparison of the available interpretation breakpoints.

MICs to tigecycline and 12 antimicrobials were performed by microdilution method, against 2423 nonduplicate pathogens recently isolated in 17 Greek hospitals. The Food and Drug Administration (FDA) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria were used comparatively for interpretation of tigecycline MICs. Tigecycline exhibited potent in vitro activity against the majority of the isolates tested. (MIC(90) values of 0.5, 1, 2, 0.125, 1, 0.25, 0.125, and 1 mg/L were observed for Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Moraxella catarrhalis, Acinetobacter spp., Staphylococcus aureus, Enterococcus spp., and Streptococcus pneumoniae isolates, respectively.) Tigecycline activity was the same, irrespective of the resistance profile to other antimicrobials (Gram-negative pathogens susceptible or resistant to imipenem, Enterococcus spp., S. aureus, or S. pneumoniae isolates, susceptible or resistant to vancomycin, methicillin or penicillin, respectively). Interpretation using EUCAST and FDA breakpoints differed among isolates of K. pneumoniae and Enterobacter spp. having tigecycline MICs of 2 to 4 mg/L. In conclusion, tigecycline exhibited potent activity against pathogens recently isolated in a region that experiences high antimicrobial resistance rates. Indications that the available criteria might categorize differently tigecycline susceptibility status in K. pneumoniae and Enterobacter spp. isolates were also detected.