In vitro dilutions of thioridaxine with potential to enhance antibiotic sensitivity in a multidrug resistant Staphylococcus aureus uropathogen

This research effort seeks to use doses of thioridaxine to enhance antibiotic sensitivity in a multidrug resistant (MDR) Staphylococcus aureus strain. Five axenic (pure) strains of S. aureus coded SA1 to SA5 were obtained from five infected midstream urine samples, inoculated on sterile cystine lactose electrolyte deficient (CLED) agar and stocked on sterile nutrient agar slants at 4°C in a refrigerator. Bacteria strains were sub-cultured on fresh sterile CLED agar and mannitol salt agar plates to confirm S. aureus strains. Gram staining, catalase test and coagulase test were done on the resulting colonies to further confirm the strains as S. aureus. Antibiotic susceptibility test was done by agar disc diffusion method using sterile Mueller- Hinton agar plates before and after treatment with laboratory dilutions of thioridaxine. S. aureus strains 1, 3 and 5 were multidrug resistant as they resisted 3 (37.5%), 3 (37.5%) and 4 (50.0%) of the antibiotics used. The highest (11.8±1.4 mm) and least (0.8±10.0 mm) zones of inhibition by all five strains were recorded for streptomycin and augmentin, respectively whereas, all five uropathogen strains resisted cloxacillin, they were sensitive to gentamycin, cotrimoxazole, chloramphenicol and streptomycin. After treatment with 2000 to 2240 ug/ml laboratory dilutions of thioridaxine, ≤50.0% loss of resistance was recorded for each of all seven dilutions but only 2240 ug/ml dilution recorded mean±S.E. loss of 56.2±17.8% for gentamycin, cotrimoxazole and streptomycin after treatment of SA5 uropathogen. This was followed by resistance losses of 41.4±10.8 and 42.7±8.3% induced by 2080 and 2200 ug/ml dilutions, respectively. Cumulative effect of all dilutions resulted in 40.0±8.2 and 40.5±17.1% borderline resistance losses to cotrimoxazole and chloramphenicol, respectively. Minimum inhibitory concentration of chloramphenicol was lowered by 2080, 2160 and 2240 ug/ml dilutions of thioridazine by four-fold (7.5 ug), four-fold (7.5 ug) and two-fold (15 ug), respectively. Upon this, the medical/chemotherapeutic implications of these findings are discussed. Key words: In vitro, dilutions, thioridaxine, enhance, antibiotic, sensitivity, multidrug resistant Staphylococcus aureus

Antibiograms of Staphylococcus Aureus and Pseudomonas Aeruginosa which Colonise the Conjunctiva of HIV/AIDS Patients in Relation to their CD4 Counts

One hundred (100) conjunctival swabs were collected from ELISA-confirmed HIV/AIDS seropositive patients who were referred to the HIV/AIDS laboratory of the University of Benin Teaching Hospital, Nigeria for routine CD4 count check. Swabs were bacteriologically processed and bacterial strains obtained from CD4 count groups were subjected to invitro antibiotic testing by disc diffusion technique in relation to their CD4 groups. Thirty four (34.0%) patients had CD4 counts within group 1 (<500 cells/µl), 36(36.0%) in group 2 (200 cells/ µl) and 30(30.0%) in group 3 (>200 cell/µl). While there was no bacterial growth after 48hrs incubation recorded for group one, only 5(13.9%) samples yielded growth of Staphylococcus aureus for group two with 31(86.1%) yielding no bacterial growth. All group three samples yielded profuse growth of which 11(36.7%) yielded Pseudomonas aeruginosa and 19(63.3%) yielded Staph aureus. Staphylococcus. aureus strains isolated from the 19(63.3%) samples showed invitro sensitivity reactions to ten antibiotics as follows: zinnat (57.0%) pefloxacine (51.3%), rocephine (51.3%) and genttamycin (50.0%). The others recorded less than 50% sensitivity. Multiple resistance to 50% of antibiotics used was shown by 5(26.3%) out of the 19 strains. The antibiogram of the 11(36.7%) Pseudomonas aeruginosa strains showed ciprofloxacin (52.3%), pefloxacine (50.0%) and gentamycin (50.0%). The remaining seven recorded less than 50% sensitivity. Of the 11(36.7%) strains, 4(36.4%) showed multiple resistance to 50% of antibiotics used. The 5(13.9%) Staph. aureus strains showed invitro antibiotics sensitivity reactions as follows: pefloxacine (65.0%), gentamycin (60.0%), rocephine (55.0%), ciprofloxacin (55.0%) and streptomycin (50.0%). Others recorded less than 50% reaction and none of the strains recorded multiple resistance. Unpaired t-test analysis showed that whereas the differences in susceptibilities of both organisms to ofloxacine, pefloxacine, gentamycin, ampicillin, zinnat, rocephine, ciprofloxacin and sperfloxacin were insignificant (P>5.0), differences in susceptibilities to streptomycin was highly significant (P<0.001) and significant to augmentin (P<0.05). The implications/significance of these findings are discussed