Fungal Endophthalmitis: Clinical Characteristics, Pathogens, and Factors Affecting Visual Outcome.

AIMS: The aims of this study are to investigate the etiology, microbiological spectrum, and risk factors associated with visual outcomes of fungal endophthalmitis (FE) in a tertiary eye specialty hospital in Shanghai, China. METHODS: This was a retrospective, single-center case series. The clinical characteristics, etiology, microbiological spectrum, and management, as well as the visual outcomes, were analyzed. Logistic regression was used to analyze the factors related to visual outcomes. RESULTS: This study involved 102 eyes of 92 patients with FE, including 63 males (66.3%). The mean age was 44.4 ± 19.8 years. The most common etiology of FE was trauma (56.5%). The predominant fungal species isolated were Aspergillus spp. (31/93, 33.3%). Pars plana vitrectomy (PPV) and intravitreal antifungal agents was performed initially in 86 (84.3%) and 83 (81.4%) eyes, respectively. Only 35 (34.3%) eyes achieved final best corrected visual acuity (BCVA) of 20/400 or better. Ten (9.8%) eyes had a final BCVA of light perception or worse, and five (4.9%) had to be enucleated. The factors determining better visual outcomes included initial visual acuity better than finger-counting (FC) (odds ratio (OR) 5.811, p = 0.036), the absence of corneal infiltrate (OR 10.131, p = 0.002), and Candida species infection (OR 6.325, p = 0.011). CONCLUSIONS: Early diagnosis of FE and a timely vitrectomy, combined with an intravitreal injection of an antifungal drug, can mitigate the devastating results of intraocular fungal infection. Not being infected by Aspergillus spp., an initial BCVA that was no worse than FC, and the absence of corneal involvement were related to better visual prognosis.

Management and Prognosis of Acute Post-Cataract Surgery Endophthalmitis: A 10-Year Retrospective Analysis in Eastern China.

Acute post-cataract surgery endophthalmitis (APSE) is a serious vision-threatening complication of cataract surgery. Analysis of the management and prognosis in cases of APSE may provide better guidance for future treatment. Fifty-six patients (56 eyes) diagnosed with APSE between 2013 and 2022 were retrospectively reviewed. The incidence of APSE rate was 0.020% (95% CI: 0.011-0.029%). Intraocular cultures were positive in 18 (32.1%) cases, with 21 organisms isolated. Coagulase-negative staphylococci was the predominant isolate (12/21; 57.1%). The time from surgery to the onset of endophthalmitis was 7 days (interquartile range: 3-16) in patients with good best-corrected visual acuity (BCVA) (≥20/70) and 3 days (interquartile range: 1-8) in those with poor BCVA (<20/70). Multivariate linear regression analysis revealed that initial BCVA (logMAR) (p < 0.001), time from onset to initial intravitreal antibiotics (IVAs) (p < 0.001), and positive culture of highly virulent pathogens (p = 0.018) displayed significantly positive associations with the final BCVA (logMAR). Adjunctive use of intravitreal corticosteroids and systemic antibiotics were unrelated to a favorable final BCVA. In conclusion, the severity of the visual condition at baseline, as well as delayed treatment, are risk factors for poor visual outcomes in APSE.

Ocular signs and symptoms of orthokeratology patients associated with povidone iodine-based disinfecting solution.

PURPOSE: To determine the frequency and severity of ocular symptoms and signs in new orthokeratology (ortho-k) subjects using a povidone iodine (PI) disinfecting system compared to those present before lens wear, and whether these were associated with cleaning regimes. METHODS: This study recruited 80 subjects from two myopia control studies, who used a PI disinfecting solution for routine use. Ocular symptoms and signs at baseline, one- and six-month after lens wear were reported via questionnaires and ocular examination, respectively. To determine if rates of occurrence were attributable to differences in cleaning regime, subjects were randomly assigned into four groups with respect to routine care procedures, which involved various combinations of rubbing and use of a daily and/or enzymatic cleaner. RESULTS: Sixty-eight subjects completed all aspects of the study. As there were no significant differences in incidence of signs and symptoms between the four groups before and after lens wear (Friedman tests, p > 0.07), data were combined for further analysis. Prior to lens wear, itchiness (69 %) and dryness (53 %) were the most commonly reported symptoms. The frequency and severity of all symptoms remained similar after lens wear (p > 0.10). Presence of follicles in the lower tarsal conjunctiva (22 %) and conjunctival injection (15 %) was frequently observed, but reduced significantly after lens wear (p < 0.01). Mild corneal staining, noted in 13 % of subjects at baseline, did not change significantly over time (p = 0.17). Ocular signs were not necessarily reflected in symptoms and vice versa. CONCLUSION: Use of a PI-based solution did not increase the frequency or severity of ocular signs and symptoms observed before lens wear. Absence of a difference in occurrence of ocular discomfort with respect to cleaning regimes indicated that the use of the PI-based solution may adequately clean the lenses over a 6-month period.

Effect of povidone iodine contact lens disinfecting solution on orthokeratology lens and lens case contamination and organisms in the microbiome of the conjunctiva.

PURPOSE: To compare lens cleaning routines using a povidone iodine-based rigid lens disinfecting solution and its effect on conjunctival colonisation, and lens and lens case contamination. METHODS: Participants, aged 6-10 years, receiving orthokeratology treatment were randomised to four lens cleaning routines: with and without the use of daily and/or weekly cleaners, which were performed by their parents. Conjunctival colonisation was compared before lens wear and at 1-, 3-, and 6-month after commencement of lens wear. Contamination of lenses and lens cases was investigated at these times. Organisms were identified using MALDI-TOF mass spectrometry. RESULTS: Of the 76 participants who completed the study, conjunctival colonization was present in 24 (32 %) at baseline. Of the remaining 52 participants, 34 consistently yielded no growth. Participants positive at baseline were statistically more likely to be colonized after commencement of lens wear (p = 0.020). Overall, colonization rate was reduced to 15 % (11/72) after 6-month lens wear, which reached significance for initially colonized participants (p < 0.001). Few cultures yielded potential ocular pathogens, with notably no Pseudomonas aeruginosa. Contamination rates of both lenses and lens cases were also low, with few isolations of ocular pathogens. No significant differences were observed between cleaning regimes for conjunctival colonization or contamination of lenses or cases. CONCLUSIONS: Disinfection for rigid and ortho-k lens wearers may be effectively achieved with the use of povidone iodine-based solution, apparently regardless of cleaning routine adopted in the current study. The absence of pathogens in the conjunctiva, lenses, and lens cases in the great majority of samples indicates that it can improve the safety of overnight lens wear.

Investigation of effects of orthokeratology and povidone iodine disinfecting solution on the conjunctival microbiome using MALDI-TOF mass spectrometry.

Purpose: To determine organisms present in the conjunctiva of children before and after orthokeratology lens wear, using MALDI-TOF mass spectrometry. Methods: Conjunctival samples were collected from children aged 8-12 years (inclusive) at baseline and on three occasions over the first six months of orthokeratology treatment. All lenses were disinfected using the povidone iodine-based solution every day after use. Specimens were cultured and all isolated colonies were identified using MALDI-TOF mass spectrometry. Numbers of organisms and diversity were compared over the study period and the presence of any ocular pathogens noted and participants informed, where appropriate, to enhance their compliance with lens care routine. Results: Organisms isolated from 76 children were generally similar to other studies employing culture methods. However, MALDI-TOF results yielded a wider range of species of micrococci and corynebacteria, as well as a few less frequently reported organisms. Only one culture yielded fungi. Ocular pathogens were only isolated from 9 subjects (4 before lens wear and 5 after lens wear), each on one occasion only. Diversity and numbers of organisms fell slowly over the period of the study, but the changes were not significant. Conclusions: Lens wear did not affect the overall content of the ocular microbiome, but the diversity was somewhat reduced. The incidence of ocular pathogens was low, suggesting that risk of ocular infection was not substantially increased by orthokeratology treatment using a povidone-iodine disinfecting solution.

Categorisation of myopia progression by change in refractive error and axial elongation and their impact on benefit of myopia control using orthokeratology.

AIMS: To compare the value of pre-treatment axial elongation (AE) and changes in refractive sphere (M change) for predicting the success in orthokeratology (ortho-k), in order to better identify suitable candidates for myopia control. METHODS: This study further analysed the data of 66 subjects receiving 7-month ortho-k treatment, following a 7-month observation period, during which single-vision spectacles were worn. Rate of myopia progression was determined by AE and M change and subjects categorised as slow, moderate, or rapid progressors based on these changes. Outcomes of myopia control, based on the AE reduction after ortho-k, were classified as 'ineffectual', 'clinically insignificant', or 'beneficial'. RESULTS: Of the 20 subjects, initially categorised as slow by AE and, of whom 95% were similarly categorised by M change, none benefitted from ortho-k. In contrast, of the 22 subjects with moderate AE, 77% and 23% displaying slow and moderate M change, respectively, the majority (73%) benefitted from ortho-k lens wear. The 24 subjects with rapid AE were poorly identified by M change, with only 21% correctly categorised. The vast majority of rapid progressors showed significant benefit after ortho-k. CONCLUSION: Progression of AE is a good indicator of subsequent success of ortho-k treatment. Delaying commencement of therapy is prudent for children with slow progression as results indicate that they would be unlikely to benefit from this intervention. As change in refractive error frequently underestimates rapid progression of AE, its value for identifying appropriate candidates for myopia control is poor.

Regional differences in temporal incidence of Clostridium difficile infection: a systematic review and meta-analysis.

BACKGROUND: Previous decades have witnessed a change in the epidemiology of Clostridium difficile infections. This study aimed to determine temporal trends in the incidence of C difficile infection across geographic regions. METHODS: An initial search of the relevant literature was conducted from date inception to October 2018 without language restriction. We estimated the pooled incidences using logit transformation, weighted by inverse variance. The Joinpoint Regression Analysis Program was used to explore its temporal trend. RESULTS: Globally, the estimated incidence of C difficile infection increased from 6.60 per 10,000 patient-days in 1997 to 13.8 per 10,000 patient-days in 2004. Thereafter, a significant downward trend was observed, at -8.75% annually until 2015. From 2005 to 2015, the incidences in most European countries decreased at a rate between 1.97% and 4.11% per annum, except in France, where an increasing incidence was observed (ß = 0.16; P < .001). The incidences have stabilized in North America over the same period; however, in Asia, the incidence increased significantly from 2006 to 2014 (annualized percentage change = 14.4%; P < .001). The increase was greatest in Western Asian countries, including Turkey and Israel (ß > 0.10; P < .004). CONCLUSIONS: This study revealed rapid changes in the incidence of C difficile infection. This meta-analysis should inform the allocation of resources for controlling C difficile infection and future surveillance efforts in countries where epidemiologic information on C difficile infection remains sparse.

Risk factors associated with contamination of orthokeratology lens cases.

PURPOSE: To evaluate the risk factors associated with contamination of lens cases in a group of orthokeratology (ortho-k) lens wearers. METHOD: Ortho-k patients attending the Contact Lens Clinic of the Hospital were required to complete a checklist about their routine daily care and handling of lens cases. Their cases were then collected for analysis. Contamination was evaluated by determining the optical density (OD) of crystal violet stained biofilm present in the cases. OD values were divided into three groups, lower, middle, and upper tertiles, and associations between risk factors were determined by multivariate analysis. RESULTS: A total of 194 subjects were recruited. Twenty-five subjects used cylindrical lens cases (CC), 98 flat cases with ridges (FCR), and 71 flat cases without ridges (FC). FCRs were the most heavily contaminated and CC showed least contamination (FCR > FC, OR 2.16, CI 1.11-4.18, p =  0.023; FCR > CC, OR 8.86, CI 2.97-26.44, p <0.001; FC > CC, OR 2.33, CI 1.35-12.45, p =  0.013). Replacing lens cases monthly significantly reduced the risk of high contamination (OR 0.013, CI 0.06-0.30, p <  0.001), compared to those used for three months. Cases that were not rinsed (OR 3.44, CI 1.50-7.86, p =  0.003) or rinsed by other methods (OR 4.07, CI 1.67-9.92, p =  0.002) had significantly more contamination, compared to those rinsed with multipurpose solution. Lens cases, which were not dried (OR 11.36, CI 2.06-62.93, p =  0.005) or air-dried (OR 8.71, CI 1.16-65.56, p =  0.036), showed more contamination compared to those wiped with tissue daily. CONCLUSION: Case design (cylindrical), monthly replacement, daily rinsing with MPS, and wiping with tissue daily can effectively reduce biofilm formation in contact lens cases.

Microbiological evaluation of different hand drying methods for removing bacteria from washed hands.

Proper drying of hands after washing is an integral part of hand hygiene. An experimental study on 30 subjects using multiple comparisons of six hand drying methods including 1) drying on own clothes, 2) drying with one paper towel, 3) drying with two paper towels, 4) drying with a warm air dryer while holding hands stationary for 20 s, 5) drying with a warm air dryer while hand rubbing for 20 s, and 6) drying with a jet air dryer until complete dryness was achieved. It aimed to determine the effectiveness of different hand drying methods for removing bacteria from washed hands, so as to identify the optimum method using minimum resources. Our study demonstrated that the use of jet air dryers is the best method to eliminate bacteria on hands, whereas drying hands on one's own clothes is the least effective. Drying hands in a stationary position could remove more bacteria than rubbing hands when using a warm air dryer for 20 s, which mimics people's usual hand-drying practice. No significant difference in bacteria reduction was detected between the use of one or two paper towels for hand drying; therefore, using fewer resources is recommended to maintain environmental sustainability.

Evaluation of prevention and disruption of biofilm in contact lens cases.

PURPOSE: The presence of biofilm in the lens case has been shown to be a risk factor for contamination of lenses and consequently microbial keratitis. This study aimed to evaluate effectiveness of solutions for rigid contact lenses in prevention and disruption of biofilm in lens cases and methods for biofilm detection. METHOD: This study adopted a stepwise approach to evaluate effectiveness of four rigid lens disinfecting solutions against biofilm. These included two polyhexamethylene bigiuanide (PHMB) solutions and a chlorhexidine/PHMB-based solution, as well as a novel povidone-iodine formulation. The presence of biofilm following exposure to the solutions was assessed using both crystal violet (CV) staining and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) viability assay, taking into account the effect of lens case design. Three lens case designs, conventional flat, large bucket type, and cylindrical cases, were investigated for the ability to trap stain and allow biofilm formation. RESULTS: Considerable differences were noted between solutions in their ability to prevent and disrupt biofilm (p < 0.001). Lens case design greatly influenced optical density (OD) measurements even in negative controls, as cylindrical cases trapped more stain, increasing OD readings. Correcting for this factor reduced variations, but could not differentiate between residues and biofilm. MTT assay revealed that both povidone-iodine and chlorhexidine-containing solutions could effectively kill > 95% of organisms, whilst PHMB-based solutions were less effective with up to 55% of staphylococci and 41% of Pseudomonas surviving at 24 h. CONCLUSION: Biofilm can rapidly form in lens cases and may not be killed by disinfecting solutions. Of the solutions tested, none were able to prevent biofilm formation or disrupt established biofilm, but those containing chlorhexidine or povidone iodine were able to penetrate the biofilm and kill organisms. Assessment of biofilm by CV assay may be confounded by lens case design. Whilst CV assay can demonstrate presence of biofilm, this technique should be accompanied by viability assay to determine bactericidal activity.

Pre-treatment observation of axial elongation for evidence-based selection of children in Hong Kong for myopia control.

PURPOSE: This study aimed to develop evidence-based guidelines for identifying suitable subjects for myopia control using orthokeratology (ortho-k). METHODS: Changes in axial elongation (AE) in the worse eyes of 66 myopic children (myopia between -0.75 and -4.50 D and astigmatism <2.00D, and aged 6 to <16 years old) who wore single-vision spectacles for seven months before switching to orthokeratology treatment for another seven months were observed. RESULTS: AE during ortho-k lens wear was affected by age and rate of progression during spectacle wear. The percentage of subjects with rapid, moderate, and slow AE (equivalent annual myopia progression; rapid: ≥1.00D; moderate: 0.50D to <1.00D; slow: <0.50D) during spectacle wear was 36.3%, 33.3% and 30.3%, respectively. Rapid progression was most common in subjects aged less than nine, but 25% of subjects aged 9 to <13 and 12.5% aged 13 to <16 also demonstrated rapid progression. All subjects with rapid AE during spectacle wear achieved a significant reduction in eye elongation with ortho-k lens wear. Guidelines for patient selection was proposed based on the initial age and history of myopia progression. CONCLUSIONS: Myopia control is indicated for children at risk of developing high myopia. The suggested guidelines can help practitioners to identify children for whom the benefits outweigh the risks of serious adverse events.

Disturbing the balance: effect of contact lens use on the ocular proteome and microbiome.

Contact lens wear is a popular, convenient and effective method for vision correction. In recent years, contact lens practice has expanded to include new paradigms, including orthokeratology; however, their use is not entirely without risk, as the incidence of infection has consistently been reported to be higher in contact lens wearers. The explanations for this increased susceptibility have largely focused on physical damage, especially to the cornea, due to a combination of hypoxia, mechanical trauma, deposits and solution cytotoxicity, as well as poor compliance with care routines leading to introduction of pathogens into the ocular environment. However, in recent years, with the increasing availability and reduced cost of molecular techniques, the ocular environment has received greater attention with in-depth studies of proteins and other components. Numerous proteins were found to be present in the tears and their functions and interactions indicate that the tears are far more complex than formerly presumed. In addition, the concept of a sterile or limited microbial population on the ocular surface has been challenged by analysis of the microbiome. Ocular microbiome was not considered as one of the key sites for the Human Microbiome Project, as it was thought to be limited compared to other body sites. This was proven to be fallacious, as a wide variety of micro-organisms were identified in the analyses of human tears. Thus, the ocular environment is now recognised to be more complicated and interference with this ecological balance may lead to adverse effects. The use of contact lenses clearly changes the situation at the ocular surface, which may result in consequences which disturb the balance in the healthy eye.

Reliability of N95 respirators for respiratory protection before, during, and after nursing procedures.

BACKGROUND: The adequate fit of an N95 respirator is important for health care workers to reduce the transmission of airborne infectious diseases in the clinical setting. This study aimed to evaluate whether adequately sealed N95 respirators may provide consistent protection for the wearer while performing nursing procedures. METHODS: Participants were a group of nursing students (N = 120). The best fitting respirator for these participants was identified from the 3 common models, 1860, 1860S, and 1870+ (3M), using the quantitative fit test (QNFT) method. Participants performed nursing procedures for 10-minute periods while wearing a backpack containing the portable aerosol spectrometers throughout the assessment to detect air particles inside the respirator. RESULTS: The average fit factor of the best fitting respirator worn by the participants dropped significantly after nursing procedures (184.85 vs 134.71) as detected by the QNFT. In addition, significant differences in particle concentration of different sizes (>0.3, >0.4, >1.0, and >4.0 µm) inside the respirator were detected by the portable aerosol spectrometers before, during, and after nursing procedures. CONCLUSIONS: Body movements during nursing procedures may increase the risk of face seal leakage. Further research, including the development of prototype devices for better respirator fit, is necessary to improve respiratory protection of users.

Awareness of tick-borne disease and compliance with using tick preventive products of dog owners in Hong Kong.

Tick-borne disease in dogs is common in South-east Asia and includes babesiosis and ehrlichiosis. These diseases can be largely prevented by compliant use of tick preventive products. This study investigated knowledge of ticks and tick-borne disease and use of tick preventive agents by a large sample of dog owners in Hong Kong. A total of 492 valid questionnaires were completed by owners attending veterinary practices, approached by researchers at common dog-walking areas, or targeted via local social media sites for pet owners. A high proportion of respondents were aware of tick-borne disease (79%) and this correlated well with use of preventive products. However, 18% of owners did not use any protection, mainly due to lack of knowledge of the risk of disease. Targeted advice stressing the importance of tick protection use and frequent follow-up at veterinary clinics could help reduce the risk of tick-borne disease. It would be beneficial if veterinarians provided training of frontline staff at the clinics to ensure they provide essential information to clients in an easily understandable format.

Effects of Lead Phytochemicals of Radix Scutellariae on Acanthamoeba.

Purpose: Acanthamoeba keratitis (AK), which is associated with noncompliant use of contact lenses, remains difficult to treat due to delayed diagnosis and paucity of therapeutic agents. Although improvements in activity against Acanthamoeba infection have been achieved in disinfecting solutions for soft contact lenses, such modifications have not been extended to those for special rigid gas permeable (RGP) contact lenses, which are increasingly used for myopia control in children. Phytochemicals present in herbs used for traditional Chinese medicine may be effective as therapeutic or preventive agents. The purpose of this study was to investigate amoebicidal properties of lead phytochemicals of Radix scutellariae alone and in combination with multipurpose (disinfecting) solutions (MPS) for RGP lenses. Methods: Viability of Acanthamoeba castellani and A. polyphaga trophozoites was determined following exposure to four phytochemicals: baicalin, baicalein, wogonoside, and oroxylin A and both alone and in combination with four RGP MPS, using a modified stand-alone technique. Results: As individual agents, wogonoside and oroxylin A showed highest activity against A. castellani and A. polyphaga trophozoites, respectively. For both organisms, the combination of baicalein and oroxylin A was superior. Effectiveness of MPS alone did not exceed 0.27 log reduction, but addition of combined baicalein and oroxylin A resulted in 0.92 and 0.64 log reductions of A. castellani and A. polyphaga, respectively. Conclusions: The combination of baicalein and oroxylin A enhanced the activity of MPS for RGP contact lenses against trophozoites of two pathogens, A. castellani, and A. polyphaga, and offers a potential therapeutic and/or preventative agent for AK.

A quasi-experimental study to determine the effects of a multifaceted educational intervention on hand hygiene compliance in a radiography unit.

BACKGROUND: Whilst numerous studies have investigated nurses' compliance with hand hygiene and use of alcohol-based hand rub (ABHR), limited attention has been paid to these issues in allied health staff. Reports have linked infections to breaches in infection control in the radiography unit (RU). With advances in medical imaging, a higher proportion of patients come into contact with RU staff increasing the need for good hand hygiene compliance. This study aimed to evaluate effectiveness on compliance of an intervention to improve awareness of hand hygiene in the RU of a district hospital. METHODS: A quasi-experimental study design including questionnaires assessing knowledge and attitudes of hand hygiene and direct observation of participants was used to evaluate an educational programme on hand hygiene of the RU of a large district hospital. All healthcare workers (HCW), comprising 76 radiographers, 17 nurses, and nine healthcare assistants (HCA), agreed to participate in the study. Of these, 85 completed the initial and 76 the post-test anonymous questionnaire. The hand hygiene compliance of all 102 HCW was observed over a 3-week period prior to and after the intervention. The 2-month intervention consisted of talks on hand hygiene and benefits of ABHR, provision of visual aids, wall-mounted ABHR dispensers, and personal bottles of ABHR. RESULTS: Before the intervention, overall hand hygiene compliance was low (28.9 %). Post-intervention, compliance with hand hygiene increased to 51.4 %. This improvement was significant for radiographers and HCA. Additionally, knowledge and attitudes improved in particular, understanding that ABHR can largely replace handwashing and there is a need to perform hand hygiene after environmental contact. The increased use of ABHR allowed HCW to feel they had enough time to perform hand hygiene. CONCLUSIONS: The educational intervention led to increased awareness of hand hygiene opportunities and better acceptance of ABHR use. The reduced time needed to perform hand rubbing and improved access to dispensers resulted in fewer missed opportunities. Although radiographers and other allied HCW make frequent contact with patients, these may be mistakenly construed as irrelevant with respect to healthcare associated infections. Stronger emphasis on hand hygiene compliance of these staff may help reduce infection risk.

Prevalence of antiseptic resistance genes increases in staphylococcal isolates from orthokeratology lens wearers over initial six-month period of use.

The purpose of this study was to investigate the prevalence of antiseptic-resistance (QAC) genes in staphylococci colonizing periorbital tissues and accessories of orthokeratology (ortho-k) lens wearers over a 6-month period and determine the effect of their presence on minimum inhibitory (MIC) and bactericidal concentrations (MBC) of disinfectants and log reduction of multipurpose contact lens solutions (MPS). Staphylococci were isolated from periorbital tissues and accessories of patients before commencing ortho-k therapy and at two subsequent visits. Presence of QAC genes in 116 S. aureus and 67 CNS isolates was determined by PCR and association with period of ortho-k use determined. MICs and MBCs of staphylococci gene-positive were compared with gene-negative strains and the effectiveness of four MPS for rigid contact lenses investigated. S. aureus carriage rates in the conjunctiva decreased significantly from 41.2 % (baseline) to 11.8 % (3-months), and 13.3 % (6-months) (p trend 0.03), while CNS increased from 58.8 %(baseline) to 94.1 % (3-months), and 93.3 % (6-months) (p trend 0.02). Prevalence of qacA/B increased considerably over time (S. aureus: 4.4 % to 15.4 %, CNS: 6.7 % to 25 %), but frequency of smr was relatively stable. Only five CNS isolates harboured qacH. MICs and MBCs of gene-positive isolates were significantly increased and three MPS did not achieve a 3-log reduction of many QAC-positive strains. Ortho-k lens wear contributed to changes of staphylococcal carriage rates in the conjunctival sac. Use of MPS containing quaternary ammonium compounds may select for the carriage of organisms harbouring QAC genes, as the low concentration of disinfecting agents is not adequate for killing gene-positive strains.

Microbial Contamination of Periorbital Tissues and Accessories of Children.

PURPOSE: To investigate normal flora of children with and without orthokeratology (ortho-k) treatment, and the associations between carriage of Staphylococcus aureus and Gram-negative rods with contamination of contact lenses and lens cases in ortho-k subjects and with spectacles of control subjects. METHODS: Twenty-three ortho-k subjects (treatment >12 months) and 20 control myopic subjects aged 7-14 years were recruited. Samples were collected from four sites surrounding the left eye (lower conjunctiva, upper and lower eyelids, and eyelashes) for all subjects, spectacles for control subjects and contact lens accessories for ortho-k subjects. Samples were cultured, total numbers enumerated, and isolates identified using chromogenic agars. RESULTS: Ortho-k subjects had significantly less total isolates in the conjunctiva than controls (p = 0.009). Otherwise, carriage rates in normal flora levels of the peri-orbital tissues were not significantly different between the two groups (p > 0.19). The total isolates and carriage rates of normal flora on spectacles, contact lenses, and lens cases were similar to those identified on the skin tissues. Small numbers of bacteria were identified from the multipurpose solution of two ortho-k subjects. Although the association between the carriage of S. aureus with contamination of accessories was statistically significant only in control subjects (p = 0.03), ortho-k subjects not yielding S. aureus and Gram-negative rods from samples of their peri-orbital tissues tended to be less likely to have these organisms in their accessories. No Pseudomonas was isolated from any of the sites sampled and no Acinetobacter was isolated from any of the accessories. CONCLUSIONS: Ortho-k may lower the total number of bacteria in conjunctiva due to the use of solution and lenses, but the physiologic effect of this treatment on the types of normal flora in children was minimal and should not increase the risk of microbial keratitis in children with good compliance.