Keratitis In Australia Research Articles

Comparison of susceptibility of Pseudomonas aeruginosa isolated from keratitis to antibiotics and multipurpose disinfecting solutions

PurposeThis study aimed to assess the susceptibility of ocular isolates of Pseudomonas aeruginosa to two multi-purpose disinfectant solutions (MPDS) and to determine if there was a relationship with resistance to antibiotics. MethodsTwenty-three strains of P. aeruginosa isolated from microbial keratitis cases in Australia were utilized in this study. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of two commercially available MPDSs, Biotrue and cleadew MPS were determined. Additionally, the MIC of the strains to five antibiotics, ciprofloxacin, levofloxacin, gentamicin, ceftazidime, and imipenem, were analyzed. ResultsAll strains were susceptible to 100 % of each of the MPDS. However, when MPDSs were diluted, cleadew MPS had significantly lower median MIC (median = 12.5 vs 25; p = 0.00008) and MBC (median = 25 vs 50; p = 0.0027) compared to Biotrue. All tested strains were susceptible to levofloxacin and gentamicin. Susceptibility rates to ciprofloxacin, imipenem, and ceftazidime were 52.2 %, 30.4 %, and 91.3 %, respectively. There were no significant relations between MIC or MBC to either MPDS and resistance to the antibiotics (p≧0.23). ConclusionBoth MPDSs were active against P. aeruginosa isolated from microbial keratitis in Australia. However, after dilution, cleadew MPS remained active against P. aeruginosa at lower concentrations. Certain strains of P. aeruginosa were resistant to imipenem, ceftazidime or ciprofloxacin. The lack of association of susceptibility to MPDS and antibiotics suggest that resistance to one did not predispose to resistance to the other.

Prevalence and seasonal variation of Acanthamoeba in domestic tap water in greater Sydney, Australia

BackgroundThis study examined the prevalence of free‐living Acanthamoeba in domestic tap water in the greater Sydney region, Australia, and determined any seasonal variation in prevalence.MethodsFifty‐four participants were included in this study following approval from an institutional human research ethics committee. Each participant self‐collected two samples (one in summer and another in winter) from the surface of the drain of the bathroom sink using an instructional kit. The samples were cultured by inoculating onto a non‐nutrient agar plate seeded with Escherichia coli and incubation at 32°C for two weeks. The plates were microscopically examined for the presence of free‐living amoeba. DNA was isolated from 20 samples and a polymerase chain reaction (PCR) assay was performed for amplification of the partial sequence of the 18S ribosomal RNA gene. The PCR amplified products were sequenced using Sanger sequencing and genotyping was performed based on the variation in nucleotide sequences.ResultsA total of 97 samples were collected over the two collection periods, with 28.6 per cent of samples morphologically classified as Acanthamoeba. The summer period yielded 16 of 54 (29.6 per cent) samples classified as Acanthamoeba, while the winter period yielded 12 of 43 (27.9 per cent) samples classified as Acanthamoeba. There was no statistically significant difference (p = 0.85) between the prevalence of free‐living Acanthamoeba in summer compared to winter. Phylogenetic analysis showed that 15 of 20 (75 per cent) isolates belonged to genotype T4, the most frequent genotype isolated in Acanthamoeba keratitis.ConclusionThe prevalence of free‐living Acanthamoeba characterised morphologically in domestic tap water of the greater Sydney region was higher than expected, especially considering the low incidence of Acanthamoeba keratitis in Australia. However, this study did not find variation between seasons. As the T4 genotype was most common, Sydney‐based practitioners must always consider Acanthamoeba as a possible causative organism in cases of microbial keratitis, regardless of the season.

Antibiotic Resistance Characteristics of Pseudomonas aeruginosa Isolated from Keratitis in Australia and India.

This study investigated genomic differences in Australian and Indian Pseudomonas aeruginosa isolates from keratitis (infection of the cornea). Overall, the Indian isolates were resistant to more antibiotics, with some of those isolates being multi-drug resistant. Acquired genes were related to resistance to fluoroquinolones, aminoglycosides, beta-lactams, macrolides, sulphonamides, and tetracycline and were more frequent in Indian (96%) than in Australian (35%) isolates (p = 0.02). Indian isolates had large numbers of gene variations (median 50,006, IQR = 26,967–50,600) compared to Australian isolates (median 26,317, IQR = 25,681–33,780). There were a larger number of mutations in the mutL and uvrD genes associated with the mismatch repair (MMR) system in Indian isolates, which may result in strains losing their efficacy for DNA repair. The number of gene variations were greater in isolates carrying MMR system genes or exoU. In the phylogenetic division, the number of core genes were similar in both groups, but Indian isolates had larger numbers of pan genes (median 6518, IQR = 6040–6935). Clones related to three different sequence types—ST308, ST316, and ST491—were found among Indian isolates. Only one clone, ST233, containing two strains was present in Australian isolates. The most striking differences between Australian and Indian isolates were carriage of exoU (that encodes a cytolytic phospholipase) in Indian isolates and exoS (that encodes for GTPase activator activity) in Australian isolates, large number of acquired resistance genes, greater changes to MMR genes, and a larger pan genome as well as increased overall genetic variation in the Indian isolates.

Acanthamoeba keratitis in Australia: demographics, associated factors, presentation and outcomes: a 15-year case review.

To report the demographics, frequency of potential predisposing factors, presentation and outcomes of Acanthamoeba keratitis (AK) at a quaternary eye hospital in Sydney, Australia over a 15-year period. A retrospective review of all patients diagnosed with AK at the Sydney Eye Hospital, Sydney, Australia between January 2002 and December 2016 was conducted. A total of 52 patients with AK at the quaternary referral hospital in Sydney, Australia, between January 2002 and December 2016, were included. The most commonly documented potential predisposing factors were contact lens wear (83%) and organic trauma (10%) in the non-contact lens wearers. An initial misdiagnosis of herpetic eye disease was made in 37% of patients. The presenting clinical features in order of frequency included; punctate epitheliopathy in 65% (n = 34), perineural infiltrate 46% (n = 24), stromal infiltrates 46% (n = 24), anterior uveitis 39% (n = 20), epithelial defect 35% (n = 18), limbitis 31% (n = 16), pseudo-dendrite 19% (n = 10), and ring infiltrate 4% (n = 7). Twenty-seven of the patients completed their follow-up at the Sydney Eye Hospital, improving their vision from 1.02 logMAR at presentation to 0.57 logMAR at last follow-up. Thirty-nine complications developed in 32 eyes and included corneal scarring and vascularisation, three patients experienced recurrences of AK and one patient developed a late-onset scleritis. In Australia, AK occurred predominantly in contact lens wearers with typical clinical features including epitheliopathy and perineural infiltrates. The patient demographics, frequency of potential predisposing factors and clinical presentation of AK were similar to case series from the UK and New Zealand.

Keratitis antimicrobial resistance surveillance program, Sydney, Australia: 2016 Annual Report.

Antimicrobial resistance data from bacterial keratitis in Australia are lacking. Antimicrobial resistance is a global health threat. Bacterial keratitis is an ophthalmic emergency requiring immediate and effective treatment. Retrospective cohort study of bacterial isolates and antibiotic susceptibility profiles at a quaternary hospital in Sydney, Australia. Two hundred and twenty-four corneal scrapes from patients from January 1 to December 31, 2016. Matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry identified bacteria. The Calibrated Dichotomous Sensitivity (CDS) method determined antibiotic susceptibilities. Isolated organisms and antibiotic susceptibilities. One hundred and sixty-eight scrapes of 224 (75%) were culture positive. One hundred and thirty-one patients had a single organism isolated and 21 had mixed bacterial growth. Of the 157 organisms isolated, 131 (83%) were Gram-positive and 27 (17%) Gram-negative. Of the Gram-positive organisms, 75 (57%) were coagulase-negative Staphylococci (CoNS), 15 (11%) Staphylococcus aureus (including one methicillin-resistant Staphylococcus aureus [MRSA]) and 8 (6%) Corynebacterium spp. Of the Gram-negative organisms, 15 (58%) were Pseudomonas aeruginosa. With methicillin-sensitive Staphylococcus aureus (MSSA) resistance to chloramphenicol was 21%, ciprofloxacin 7% and gentamicin 7%. With CoNS resistance to cefalotin was 9%, gentamicin 9% and ciprofloxacin 9%. With Corynebacterium spp. resistance was 40% to cefalotin, chloramphenicol 25% and ciprofloxacin 14%. Staphyloccocus spp. and Pseudomonas spp. were the most common microorganisms isolated. There was low resistance to cefalotin and ciprofloxacin for these isolates. More than 90% of these would be covered by current therapeutic recommendations for empiric therapy in Australia.

Gas permeable lenses are alive and well in 2010

Gas permeable lenses are alive and well in 2010

The Incidence of Contact Lens–Related Microbial Keratitis in Australia

To establish the absolute risk of contact lens (CL)-related microbial keratitis, the incidence of vision loss and risk factors for disease. A prospective, 12-month, population-based surveillance study. New cases of CL-related microbial keratitis presenting in Australia over a 12-month period were identified through surveillance of all ophthalmic practitioners (numerator). Case detection was augmented by records' audits at major ophthalmic centers. The denominator (number of wearers of different CL types in the community) was established using a national telephone survey of 35,914 individuals. Cases and controls were interviewed by telephone to determine subject demographics and CL wear history. Visual outcomes were determined 6 months after the initial event. Annualized incidence and confidence intervals (CI) were estimated for different severities of disease and multivariable analysis was used in risk factor analysis. Annualized incidence (with CI) of disease and vision loss by CL type and wear modality and identification of independent risk factors. We identified 285 eligible cases of CL-related microbial keratitis and 1798 controls. In daily wear rigid gas-permeable CL wearers, the annualized incidence per 10,000 wearers was 1.2 (CI, 1.1-1.5); in daily wear soft CL wearers 1.9 (CI, 1.8-2.0); soft CL wearers (occasional overnight use) 2.2 (CI, 2.0-2.5); daily disposable CL wearers 2.0 (CI, 1.7-2.4); daily disposable CL wearers (occasional overnight use) 4.2 (CI, 3.1-6.6); daily wear silicone hydrogel CL wearers 11.9 (CI, 10.0-14.6); silicone hydrogel CL wearers (occasional overnight use) 5.5 (CI, 4.5-7.2); overnight wear soft CL wearers 19.5 (CI, 14.6-29.5) and in overnight wear of silicone hydrogel 25.4 (CI, 21.2-31.5). Loss of vision occurred in 0.6 per 10,000 wearers. Risk factors included overnight use, poor storage case hygiene, smoking, Internet purchase of CLs, <6 months wear experience, and higher socioeconomic class. Incidence estimates for soft CL use were similar to those previously reported. New lens types have not reduced the incidence of disease. Overnight use of any CL is associated with a higher risk than daily use.

Referral pathways and management of contact lens‐related microbial keratitis in Australia and New Zealand

We examine the referral pathways and treatment for contact lens-related microbial keratitis in Australia and New Zealand. Cases were reported in May 2003-September 2004; data on presentation, referral and treatment collected from practitioners and via patient interview. Severity was graded, 1-week cure rate estimated, delays in treatment and medications documented. Hospital and private clinic managements were compared. A total of 297 eligible cases were reported; detailed information on treatment and referral pathways was available on a subset of these cases. Presentation was to optometrists (81/200, 41%), general practitioners (GPs) (69/200, 34%) or emergency departments (46/200, 23%). Optometrists referred to private ophthalmologists (47/79, 60%) more often than hospitals (27/79, 34%). GPs initiated treatment (39/68, 57%) but also referred to hospitals (22/68, 32%) and to private ophthalmologists (7/68, 10%). Of all cases, 67% (195/297) were managed in hospitals (29% admitted, 87/297). Hospitalized cases were predominantly managed with fortified aminoglycoside/cephalosporin (66/81, 82%) and others fluoroquinolones (168/195, 86%). Steroids were used in 36% (98/276) commencing on day 5 (median, interquartile range = 3-7). One-week cure rate was 60% (49/82) in private clinics, 72% (62/86) for hospital outpatient cases and 37% (25/67, P < 0.001) for inpatient cases, which were more severe diseases (47%, 52% and 0% mild, respectively). Delays (>/=12 h) receiving therapy were experienced by 33% (55/168) because of initial inappropriate treatment (48/55), time delays (7/55) but not remoteness (P = 0.6). The majority of treatment is via hospital clinics, but milder disease is managed in private clinics. The referral process via optometrists, GPs and emergency departments is generally efficient; however, one-third of cases experienced some delays before receiving appropriate therapy highlighting the need for timely diagnosis.

Who should manage contact lens related microbial keratitis in Australia and New Zealand?

Who should manage contact lens related microbial keratitis in Australia and New Zealand?

A Longitudinal Study of Trends in Keratitis in Australia

To analyze the changes in risk factors, corneal culture results, antibiotic resistance, treatment, and clinical outcomes of patients with keratitis presenting to a major public hospital in Australia over a 5-year period. A retrospective audit of all patients who had a corneal scraping between October 1999 and September 2004 at the Princess Alexandra Hospital. Clinical information was gathered from medical records and smear and culture results from the local microbiology database. The trends over time in patient demographics, keratitis risk factors, corneal culture results, antibiotic resistance, treatment, and clinical outcomes were analyzed by using linear regression. By using a moving average, we analyzed differences in the rate of culture of each causative organism for each month of the year with linear regression from the month of highest presentation. The mean of maximum temperatures on the days of presentation between different groups of organisms was compared. The proportion of patients presenting with keratitis related to contact lens wear increased significantly (12%-29%; P = 0.04) and with keratitis related to ocular surgery decreased significantly (18%-8%; P = 0.009) through the study. Antibiotic resistance of cultured bacteria to cephalothin increased significantly (2%-12%; P = 0.02), whereas resistance to ciprofloxacin and gentamicin remained at a low level throughout the study. There was significant variation in the monthly recovery of Pseudomonas aeruginosa (P = 0.04) and fungi (P = 0.02), which were cultured more frequently in summer months, whereas Streptococcus pneumoniae (P = 0.04) was more common in winter months than in other times of the year. Treatment with fluoroquinolones increased significantly (14%-40%; P = 0.002) through the study, and the rate of good outcomes also increased significantly (42%-72%; P = 0.02). In this series, keratitis related to contact lens wear became more frequent, whereas keratitis related to prior ocular surgery became less frequent. Different organism groups showed significant seasonal variations in their presentation, and bacterial resistance to cephalothin increased significantly.

Studies of Contact Lens–Related Microbial Keratitis in Australia and New Zealand: New Learnings

This manuscript reports the design of a multi source surveillance study of contact lens-related microbial keratitis in Australia and New Zealand. It describes and evaluates a new combination of techniques not previously used in ophthalmic epidemiology, intended to deliver a more robust methodology appropriate to detecting cases of contact lens related microbial keratitis in the light of increased community management of this condition. Ophthalmic practitioners in Australia and New Zealand were surveyed 6 times over a 12 month period to detect cases of contact lens-related microbial keratitis. Case detection involved both active and passive surveillance, Internet reporting to capture whether or not cases had been seen during the reporting period and audit of major ophthalmic centres. Good response rates were obtained and maintained using this approach, with an overall participation rate of 95.8% (711/742) of ophthalmologists. Internet reporting was used by 17% and 31% of practitioners in Australia and New Zealand, respectively. However active follow up was required to elicit responses from 72.5% and 63.1% of practitioners, respectively. Twenty-five percent of cases were captured through hospital audit and 33% of cases were managed exclusively in the community. Active surveillance was essential to maintain response rates. The use of web based reporting and communication via the Internet facilitated data capture. One third of cases were managed exclusively in the community, which supports the surveillance of all ophthalmic practitioners. An additional recommendation to facilitate studies of this type would be the establishment of a national ophthalmic surveillance unit.

Relationship Between Climate, Disease Severity, and Causative Organism for Contact Lens–Associated Microbial Keratitis in Australia

To evaluate associations between disease severity, causative organism, and climatic variation in contact lens-related microbial keratitis in Australia. Prospective, observational case series. Contact lens wearing patients (n = 236) with presumed microbial keratitis presenting to private and hospital ophthalmologists in Australia between October 1, 2003 and September 30, 2004 were identified prospectively. Clinical details, management information, and microbiology data were collected and cases were graded for severity based on lesion size and location criteria. Causative organisms were assigned to "environmental" or "endogenous" groups. Climate zone and daytime temperature and humidity were determined for the geographic location of each event. The main outcome measures were disease severity, causative organism, and climate zone. Severe contact lens-related microbial keratitis was more likely to occur in warmer, humid regions of the country (P < .001), compared with smaller, increasingly peripheral corneal lesions that were more common in cooler conditions (P < .001). Culture-proven keratitis was predominantly caused by environmental organisms with Pseudomonas aeruginosa being recovered most frequently. Environmental organisms were isolated more commonly from tropical regions of the country and also accounted for nearly all cases of vision loss that occurred during the study period. Humidity did not have a significant effect on causative organism. Climatic conditions play a role in disease severity and causative organism in contact lens-related microbial keratitis and therefore have implications for practitioners involved in contact lens care and contact lens wearers who live in or travel to the tropics.

Surveillance of Contact Lens Related Microbial Keratitis in Australia and New Zealand: Multi-Source Case-Capture and Cost-Effectiveness

Purpose: To evaluate a multi-source surveillance system used in a 12-month study of contact lens related microbial keratitis in Australia and New Zealand. Methods: All practicing ophthalmologists and optometrists were surveyed on 6 occasions over 12 months via post or the Internet. Participation was defined as reporting at least once during the study period and the response rates represented those who responded on all six occasions. Cases were also detected through hospital audit. All ophthalmologists and a sub-group of optometrists were contacted by phone to elicit a response (active surveillance). The utilization and cost-effectiveness of active surveillance were compared to reports received via the post or the Internet. Case ascertainment and cost-effectiveness were compared for different sources of case capture. Results: The rate of participation for ophthalmologists was 95.8% (711/742) and 88.5% (657/742) responded for all reporting periods. Active surveillance was required for 63% (416/661) of responses in Australia (AU) and 73% (59/81) in New Zealand (NZ) at AUD23.14 per practitioner. Internet reporting was more widely used in New Zealand (NZ: 31% vs. AU:17%, p = 0.006) and was the most cost effective mode of reporting (AUD1.43 per practitioner). Postal reporting (AUD; AU:3.54,NZ:9.84 per practitioner) was under-utilized (3% of responses). Average start-up costs comprised 50% of study costs followed by active follow-up (42%), postal (6%) and Internet reporting (2%). Ophthalmologists (50.4%, 144/286 of cases) were the most cost-effective source of cases, followed by hospital audit (24.5%, 70/286) and optometry (25.1%, 72/286). Duplicate reporting occurred in 13% (37/286) of cases. Conclusions: High response rates were obtained by substantial resource commitment to active follow-up. Internet reporting was widely used and was cost-effective. Hospital audit and supplementary reporting by optometry were used for the first time in a study of contact lens related microbial keratitis, and contributed significantly to case capture.