Characterization and Antibiotic Sensitivity Pattern of Organisms Isolated from Common Cough Syrups Marketed in Nigeria

Abstract

Fifty eight (58) cough syrup samples were purchased from registered pharmacies and patent medicine stores in Nsukka, Enugu, Lagos and Onitsha. Physical, biochemical and microbiological tests were carried out on the samples in duplicates. The pHs of the samples was determined on the 1'' and 3rd days of opening the containers. The samples were diluted to produce 1 : 10 and 1 :3 dilutions using Tween 85 normal saline solution and normal saline respecti\;ely. The viable microbial counts were estimated for each of the samples using Miles and Misra method on sterile overdried Nutrient agar and Sabouraud Dextrose agar plate. The microorganisms isolated from the cough syrup samples were identified, characterized and their antibiotic sensitivity patterns were established. Sensitivity tests were carried out on the bacterial isolates using the Abtek Biological disks containing standard antibiotics -: Cephalexin (CLX)- 30mg, Amoxicillin (AMX) -25mg ,Cotrimoxazole (COT) - 25mg ,Dalacin C (DAL) – 2mg, Flucloxacillin (FLX) - 5mg ,Minocyclin (MIN) -30mg ,Erythromycin (ERY) - 15mg and lincomycin (LIN) - 15mg, while the sensitivity tests on the fungal isolates were carried out using prepared standard fungal antibiotics - Nystatin (NYS) -100 IU ,Fulcin (FUL) - 5inghl ,Tioconazole (TIO) -1mghl ,Ketoconazole (KET) - lmghl ,Miconazole (MIC) - 5mghl , Salicylic acid (SAL) 10 mghl and Clotrimazole (CLO) - 1 mghl. Solutions were employed for the well agar diffusion techniques and disks for the disk agar diffusion techniques. All the isolates were Gram stained. Further identification of the bacterial isolates were carried out using biochemical tests including - sugar fermentation tests, starch hydrolysis, catalase, citrate coagulase, methyl red - Voges Proskauer, sulphide and indole production tests, motility, nitrate reduction and oxidase tests. The fungal isolates were identified using the lactophenol - cotton blue stain. The Gram negative organisms we're cultured on salmonella - shigella agar, eosine methylene blue agar and MacConkey agar and their growth characteristics were observed. The presence of Candida albicans was confirmed using the germ tube test. The mean pH values of the cough syrup samples ranged from 3.18 - 6.84 on the first day of opening the containers and 3.33 - 7.01 by the third day. Thirty-five per cent of the samples had pH values less than 4 which decreased to twenty-one per cent after three days. Thirty-eight per cent of the samples had microbial growth on dilution with Tween 85 normal saline solution. While twenty-six per cent had growth both on Tween 85, normal saline solution and normal saline. The mean viable bacterial and fungal counts ranged from 0 - 1.74 x lo5 and 0 - 1.3 x lo5 respectively. The bacteria isolated are Bacillus subtilis, Klebsiella pneumoniae, Salmonella typhi and Enterococcus faecalis. The fungi and yeast species isolated were Aspergillus niger , ~enicillum notatunl , Fusarium spp and Candida albicans .The inhibition zone diameter (IZD) of the antibiotics against the bacteria and fungal isolates were in order :COT > MM XLX > ERY> AMX >FLX >LIN> DAL and TI0 >KET > MIC > CLO > NYS >SAL >FUL respectively. All the isolates had Multiple Antibiotic Sensitivity (MAS) to the antibiotics. The IZD to the selected antibiotic against ninety-five per cent of the bacterial isolates (IZDg5) ranged froin 17.3 - 39.3 mm and their activity was in the order COT > MIN> CLX> ERY >AMX >FLX >DAL >LIN, while the IZD of the selected antibiotics against ninety-five per cent of the fungal isolates (IZDg5) ranged from 0 - 35.45mm and the activity was in the order TI0 > KET >MIC >CLO >NYS > SAL >FUL. The IZD of the selected antibiotics against fifty per cent of the bacterial isolates (IZD50) ranged from 0 - 28mm and activity was in the order COT> MM > AMX >CLX and ERY >LIN >FLX and DAL while that of the fungal isolates ranged from 0 - 30mm with their activity in the order TI0 >KET >MIN >CLO >NYS, FUL and SAL.