Surface microbial contamination in some commonly available tablet dosage forms

Abstract

Objective: Nonprescription drugs are subject to unrestricted handling and are, therefore, potentially susceptible to postproduction contamination by microorganisms from both the handlers and the environment. The aim of this work is to investigate the occurrence of contamination of certain tablet surfaces by microorganisms. Methods: Twenty-two samples of commercially available analgesic and vitamin preparations in tablet form were obtained as sold or dispensed from retail pharmacies and clinical pharmacies in Nigeria and Kuwait. Sample surfaces of tablets were investigated by scanning electron microscopy and augmented by streaking and superficial implantation on agar media for culture development. Results: Of 22 samples tested, 14 (64%) were visually found to have surface microbial contamination. However, only 4 samples (18%) of the total samples investigated yielded positive microbial cultures on growth media. The most commonly observed surface contaminants were yeast cells. The microorganisms isolated included Saccharomyces sp., Rhodotorula rubra, coagulase-negative staphylococci and Penicillium sp. Conclusion: Commonly available nonprescription drugs in tablet dosage form have been shown to be frequently contaminated by microorganisms. However, cases of microscopic visualization of microbial contamination of drugs do not often result in recoverable cultures on growth media. Copyright © 2001 S. Karger AG, Basel.