Contact Lens Storage Case Contamination

There are several genera of micro-organisms related to contact lens storage case contamination. Unlike CL contamination which is bacterial in nature, storage case contamination is often polymicrobial.(Larkin et al. 1990; Gray et al. 1995) Gray et al found that bacterial contamination is common in 77% of lens cases, followed by contamination with fungi (24%) and then protozoan (20%). Most commonly found organisms include Pseudomonas aeruginosa, Staphylococcus spp, Acanthamoeba spp and Fusarium species from CL cases. But still there are variations in isolated organisms from contact lens storage case in different studies. Studies also have documented the most commonly recovered micro-organisms in contact lens related microbial keratitis includes
Pseudomonas, Serratia and Staphylococcus spp.(van der Meulen et al. 2008; Erie et al. 2014; Dart et al. 2008; F. Stapleton, J. Dart 1993; Lam et al. 2002; Edwards et al. 2009) Among them P. aeruginosa is the most virulent and common bacterial cause of microbial keratitis.(Dart 1988; Gray et al. 1995) and sometimes it may susceptible to CL disinfecting solution.(Lakkis et al. 2001) Another most commonly found organism is Staphylococcus spp, it the Gram negative bacteria and common facial micro biota. It’s frequent recover from the lens storage case could be a carry-over from hands to contact lens cases.(E. Leitch, N. Harmis, KM. Corrigan 1998)
Contact lens case contamination severity depends on species, genera and strains of micro-organisms.
Different microbes have different pathogenicity and at which level microbes become significant contaminant it varies on their pathogenicity. Willcox et al in their study classified isolated micro-organisms from storage cases based on their pathogenicity and assessed the level at which the microbes became contaminant.(Willcox et al. 2010b) The strength of attachment to contact lens and cases vary between genera and species and cell surface appendages, termed pili and flagella can participate in bacterial adhesion. But non-piliated P.aeruginosa also can adhere with the contact lens surfaces. The adhesion of P.aeruginosa is very fast and as little as one hour to make permanent bond with surfaces and forming colonization immediately upon attachment. So, the micro-organisms species play an important role in severity of contamination of
cases.
Table shows the rate of contact lens case contamination and profiles of micro-organisms were isolated from cases. Among them Willcox et al (2010) study reported some of the micro-organisms which were previously not mentioned in contact lens case contamination. They found most frequently colonized bacteria were Gram negative bacteria, among them Achromobacter Spp, Comamonas testosterone, Delftia acidovorans, Enterobacter spp, Klebsiella spp, Serratia spp and Stenotrophomonas spp considered to represent significant level of contamination. Few gram positive bacteria like Propionibacterium spp and Staphylococcus species were showed significant contamination instead of using disinfecting and cleaning solutions.(Willcox et al. 2010a)
Studies have shown wide range of variation in contact lens contamination organisms due to geographical location, varied in study design, sampling techniques and sample size.
Effective treatment of contact lens related corneal ulcer is dependent on the identification of the infectious and no infectious micro-organisms of the problem. But sometimes identification of the organisms is difficult because the contaminating organisms often are not cultivable. (Wiley et al. 2012) study was explored further insight into the etiology of contact lens related disease by using culture independent, 16S ribosomal RNA (rRNA) gene analysis. In their study Achromobacter, Stenotrophomonas and Delftia were the predominant bacteria rather than Pseudomonas in patient having contact lens related corneal diseases. These genera’s exhibits physiological properties similar to Pseudomonas but have different antibiotic resistance pattern. The interaction with antimicrobial contact lens storage cases with these three clinically rare gram negative bacteria is still
unknown.