Microbial contamination of multi-use ophthalmic solutions in Kenya

Abstract

Background/aims: Contaminated ophthalmic solutions represent a potential cause of avoidable ocular infection. This study aimed to determine the magnitude and pattern of microbial contamination of multi-dose ocular solutions at the Department of Ophthalmology, University of Nairobi, at the Kenyatta National Hospital, Kenya. Methods: 101 vials were obtained for microbial examination after an average use of 2 weeks. The dropper tip and the residual eye drop were examined for contamination. The specimens were cultured, the number of colonies counted, the organisms identified and susceptibility testing to selected antimicrobial agents was done. Results: Six (6%) of the 101 analysed vials were contaminated: 4/77 vials (5%) from a multi-user setting and 2/24 vials (8%) from a single user setting. Three contaminations (3/38, 8%) occurred in vials from the eye ward, another three (3/59, 5%) in vials from the outpatient clinic. Most bacteria identified belonged to the normal commensal flora of the eye. Isolated contaminants were micrococci (n = 2), Staphylococcus epidermidis, Haemophilus sp, Bacillus sp and a Gram negative rod. The dropper tip was more often contaminated (n = 6) than the residual solution (n = 1), and only one vial showed a contamination of both the drop and the tip. Conclusion: Our data show a contamination rate of 6%, which is in the lower range of data published on the contamination of eye drops elsewhere (0.07% to 35.8%).

An evaluation of the pharmaceutical quality and antimicrobial effectiveness of some frequently used eye drop products available for sale in Nigeria

“…Most reported studies have focussed patient-used preparations and high prevalence of microbial contaminations in these preparations have been reported. [7,8] Although most of these studies have attributed these contaminations to the use of the eye drops, it is doubtful if these assertions have any scientific basis since the microbial quality of the original eye drop products are largely assumed.…”

“…[7] Eye drops were opened and exposed to the atmosphere by placing them on the open shelves in the laboratory. Samples were taken at 0, 2, 4, 8, 24, 48, and 72 h, then 7, 14, 28, and 56 days.…”

“…[6] This is because, while in use, microbial contamination may lead to product degradation or result in ocular infection. [7,8] Therefore, it is essential to protect the product against the effects of opportunistic contamination by the use of appropriate preservatives. [6] To assess the suitability of the added preservative in the eye drops, the antimicrobial effectiveness tests such as the microbial challenge tests were carried out.…”

The precautionary principle: what is the risk of reusing disposable drops in routine ophthalmology consultations and what are the costs of reducing this risk to zero?

“…3 The dropper tip is more often contaminated than the residual solution in the bottle and the organisms cultured tend to be the normal commensal flora of the eye. 4 These are unlikely to cause problems but there is a risk of infection. 5 These two facts have led to the development of individual containers, which can be used on one patient as a single dose, obviating the need for preservatives, and reducing to zero the risk of cross-contamination by microorganisms commonly found on the ocular surface.…”

The reuse of opthalmic minims®: an unacceptable cross-infection risk?

“…Various studies have shown contamination of multiuse ophthalmic solutions and their applicators. [1][2][3] There is, however, little evidence that accurately assesses the safety of using Minims vials for multiple applications.…”