Antibacterial activity of penicillins alone and in combination with different agents against Staphylococcus aureus.

Difficulties in the treatment of the resistant strains of Staphylococcus aureus, which is a frequent cause of nosocomial infections in paediatric patients, has prompted this research to empower the usage of various combinations of penicillin. During the study period 17,452 clinical samples were processed for culture. The positive cultures yielded 564 strains of S. aureus. Out of these, 362 (64.2%) isolates were found to be methicillin sensitive S. aureus (MSSA) and 202 (35.8%) methicillin resistant S. aureus (MRSA). The frequency of S. aureus isolates from male patients (355; 63.1%) was found to be higher than female patients (209; 36.9%) and those from indoor wards (441; 78.2%) were more than the outdoor wards (123; 21.8%). Frequency distribution of S. aureus showed to be highest among blood 342 (60.6%) and cerebrospinal fluid 100 (17.8%) samples. The sensitivity pattern of MSSA with piperacillin-tazobactam was 344 (95.0%), ampicillin-sulbactam 340 (93.9%), co-amoxiclav 332 (91.8%) and ampicillin-oxacillin 257 (71.0%). MRSA susceptibility to piperacillin-tazobactam was 143 (71.0%), ampicillin-sulbactam 114 (56.6%), co-amoxiclav 61 (30.2%) and ampicillin-cloxacillin 18 (9%). The Cochran Mantel Haenszel test showed that the effectiveness for each penicillin was associated significantly (p<0.05) with both the MSSA and MRSA. The combinations of piperacillin-tazobactam, ampicillin-sulbactam, co-amoxiclav and ampicillin-cloxacillin exhibited higher efficacy than using them alone to combat Staphylococcal infections.

In vitro antimicrobial activity of ZnO based glass-ceramics against pathogenic bacteria.

The antibacterial activity of ZnO (0-15.53 mol%) based SiO2-CaO-P2O5-Na2O-CaF2 bioactive glass-ceramics synthesized by controlled crystallisation were studied against eight micro-organisms using modified Kirby Bauer method. The antibacterial activity of the specimens was statistically evaluated using one-way analysis of variance and P < 0.05 was used as the level of significance. In vitro dissolution tests were performed in stimulated body fluid for 48 h at 37 °C for different time intervals to correlate the dissolution behaviour of test samples with antibacterial effects. The results illustrate that specimen BZn15.53 having the highest concentration of ZnO (15.53 mol%) demonstrated the strongest effect against Staph.aureus, S. epidermidis, B. subtilis and K. pneumonia. The effectiveness of BZn15.53 in inhibiting bacteria was due to accumulation of Zn(+2) ions around the surface of the bacteria cell release that caused the death of the cell, besides the presence of hydroxyapatite phase was also responsible for damaging the cell membrane of bacteria.