An 11-year analysis of microbial keratitis in the South West of England using brain–heart infusion broth

Abstract

Background The aims of this study were to identify the organisms responsible for microbial keratitis, as identified by corneal scrape using brain-heart infusion broth, trends over time and antimicrobial sensitivities, over an 11-year period at two eye units in the South West of England; Bristol Eye Hospital and Royal United Hospital, Bath. Methods All corneal scrapes performed and sent for microbiological analysis between 4th April 2006 and 31st October 2017 at the two eye units were retrospectively reviewed. First-line treatment was monotherapy with levofloxacin 0.5% and second-line treatment was a combination of cefuroxime 5% and gentamicin 1.5%. Both direct and enrichment cultures were used. Results In total, 2614 corneal scrapes from 2116 patients (1082 female, mean age 47.7 ± 21.2 years) were identified. 38.1% (n = 996) were culture positive and 1195 organisms were cultured. In all, 91.6% were bacteria (69.4% were gram-positive, 30.6% gram-negative). Coagulase-negative Staphylococci (CoNS) were the most commonly cultured organism (n = 430). Pseudomonas aeruginosa was the most commonly identified gram-negative organism (n = 189). In total, 6.9% (n = 83) of organisms cultured were fungi. In all, 1.4% (n = 17) were acanthamoeba. There was no statistically significant trend in the organisms observed over the study period. Sensitivity testing confirmed reasonable sensitivity to the empiric antibiotics used in clinical practice. Conclusions This is the first report on microbial keratitis trends in the South West of England. Virulent organisms were likely to be detected on direct culture, whereas low virulent organisms such as CoNS were more likely to be detected on enrichment alone. Antibiotic sensitivity testing confirmed fluoroquinolone monotherapy as appropriate first-line treatment.

Infectious keratitis: an update on epidemiology, causative microorganisms, risk factors, and antimicrobial resistance

“…Only studies that reported more than 500 cases are included. Year Authors Study period Region Total CS Age (years) Female (%) Positive culture (%) Organisms a Microbiological profiles b B (%) F (%) A (%) UK and Europe 2013 Kaye et al [ 23 ] 1995–2010 Liverpool, UK 2418 – – 35.7 100 0 0 CoNS (26.3); Enterobacteriaceae (15.3); Streptococci (13.9) 2017 Tan et al [ 9 ] 2004–2015 Manchester, UK 4229 45.9 – 32.6 90.6 7.1 2.3 CoNS (24.4); S. aureus (15.1); Streptococci (13.3) 2018 Ting et al [ 10 ] 2008–2017 Sunderland, UK 914 55.9 ± 21.0 52.1 46.1 91.0 4.2 4.8 CoNS (25.9); S. aureus (13.6); Streptococci (12.1) 2019 Tavassoli et al [ 24 ] 2006–2017 Bristol and Bath, UK 2614 47.7 ± 21.2 51.1 38.1 91.6 6.9 1.4 CoNS (36.0); Pseudomonas (15.8); Streptococci (7.0) 2020 Ting et al [ 8 ] 2007–2019 Nottingham, UK 1333 49.9 ± 22.2 49.6 37.7 92.8 3.0 …”

“…IK has been shown to affect individuals across all age groups. Based on large-scale studies (>500 patients), IK most commonly affected people aged between 30 and 55 years (Table 1 ) [ 8 – 10 , 13 , 21 , 24 , 25 , 29 , 31 , 35 , 37 , 39 , 42 , 43 ], primarily attributed to the underlying risk factors such as CL wear and ocular trauma associated with the working age group. Patients affected by trauma-related IK secondary to agricultural products and foreign bodies are usually around 45–55 years old [ 18 , 44 ].…”

Morphological and cytokine profiles as key parameters to distinguish between Gram-negative and Gram-positive bacterial keratitis

“…In our Gram+ve cohort like other studies, a high number of coagulase-negative staphylococcal species (CNS) [53][54][55] , majority of which are S. epidermidis 4 . CNS represent over 80 different species and are regular isolates worldwide 53,54 and are increasingly found to be responsible for infections and disease pathogenesis 53 .…”

Staphylococcus aureus Keratitis: Incidence, Pathophysiology, Risk Factors and Novel Strategies for Treatment

“…On the other hand, another study conducted at Manchester Royal Eye Hospital found a decreasing trend of Gram-positives but a statistically significant increase in S. aureus cases over 12 years [ 9 ]. Tavassoli et al did not find a statistically significant trend in any of the microorganisms cultured over a period of 11 years in the South West of England [ 10 ]. All three of these studies found that S. aureus was not the most common cultured Gram-positive; this was instead a CNS species such as S. epidermidis .…”

“…Some studies conclude that MRSA has a higher overall resistance to multiple antibiotics compared to MSSA [ 4 , 54 ]. Others have found that MRSA is still susceptible to a variety of antibiotics such as tetracycline and gentamicin [ 10 , 55 , 56 ] and that progression to vancomycin is not always necessary [ 37 ]. Moreover, there is evidence to suggest that MSSA keratitis leads to similar visual outcomes as MRSA [ 37 ].…”