Microbial keratitis in Southern Malawi: a microbiological pilot study
Objective Microbial keratitis (MK) is a significant cause of blindness in sub-Saharan Africa. We investigated the feasibility of using a novel corneal impression membrane (CIM) for obtaining and processing samples by culture, PCR and whole-genome sequencing (WGS) in patients presenting with suspecte...
Saved in:
| Main Authors: | , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMJ Publishing Group
2024-05-01
|
| Series: | BMJ Open Ophthalmology |
| Online Access: | https://bmjophth.bmj.com/content/9/1/e001682.full |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1832086590420156416 |
|---|---|
| author | Timothy Neal Dean Everett Stephen B Kaye Alistair Darby Moira Gandiwa Shaffi Mdala Caroline E Corless Rose Herbert Nicholas A V Beare Tobi F Somerville Thokozani Zungu Malcolm J Horsburgh Petros C Kayange |
| author_facet | Timothy Neal Dean Everett Stephen B Kaye Alistair Darby Moira Gandiwa Shaffi Mdala Caroline E Corless Rose Herbert Nicholas A V Beare Tobi F Somerville Thokozani Zungu Malcolm J Horsburgh Petros C Kayange |
| author_sort | Timothy Neal |
| collection | DOAJ |
| description | Objective Microbial keratitis (MK) is a significant cause of blindness in sub-Saharan Africa. We investigated the feasibility of using a novel corneal impression membrane (CIM) for obtaining and processing samples by culture, PCR and whole-genome sequencing (WGS) in patients presenting with suspected MK in Malawi.Methods and analysis Samples were collected from patients presenting with suspected MK using a 12 mm diameter polytetrafluoroethylene CIM disc. Samples were processed using culture and PCR for Acanthamoeba, herpes simplex virus type 1 (HSV-1) and the bacterial 16S rRNA gene. Minimum inhibitory concentrations of isolates to eight antimicrobials were measured using susceptibility strips. WGS was used to characterise Staphylococcus aureus isolates.Results 71 eyes of 71 patients were included. The overall CIM isolation rate was 81.7% (58 positive samples from 71 participants). 69 (81.2%) of isolates were Gram-positive cocci. Coagulase-negative Staphylococcus 31.8% and Streptococcus species 14.1% were the most isolated bacteria. Seven (9.9%) participants were positive for HSV-1. Fungi and Acanthamoeba were not detected. Moxifloxacin and chloramphenicol offered the best coverage for both Gram-positive and Gram-negative isolates when susceptibility was determined using known antimicrobial first quartile concentrations and European Committee on Antimicrobial Susceptibility Testing breakpoints, respectively. WGS identified known virulence genes associated with S. aureus keratitis.Conclusions In a resource-poor setting, a CIM can be used to safely sample the cornea in patients presenting with suspected MK, enabling identification of causative microorganisms by culture and PCR. Although the microbiological spectrum found was limited to the dry season, these preliminary results could be used to guide empirical treatment. |
| format | Article |
| id | doaj-art-afbc5bb7b50b474cb1175d9facc42cc5 |
| institution | Kabale University |
| issn | 2397-3269 |
| language | English |
| publishDate | 2024-05-01 |
| publisher | BMJ Publishing Group |
| record_format | Article |
| series | BMJ Open Ophthalmology |
| spelling | doaj-art-afbc5bb7b50b474cb1175d9facc42cc52025-02-06T11:10:11ZengBMJ Publishing GroupBMJ Open Ophthalmology2397-32692024-05-019110.1136/bmjophth-2024-001682Microbial keratitis in Southern Malawi: a microbiological pilot studyTimothy Neal0Dean Everett1Stephen B Kaye2Alistair Darby3Moira Gandiwa4Shaffi Mdala5Caroline E Corless6Rose Herbert7Nicholas A V Beare8Tobi F Somerville9Thokozani Zungu10Malcolm J Horsburgh11Petros C Kayange12Department of Infection and Immunity, Liverpool University Hospitals NHS Foundation Trust, Liverpool, UKMalawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, MalawiDepartment of Eye and Vision Sciences, University of Liverpool, Liverpool, UKDepartment of Infection Biology and Microbiomes, University of Liverpool, Liverpool, UKOphthalmology Unit, Kamuzu University of Health Sciences, Blantyre, Southern Region, MalawiQueen Elizabeth Central Hospital, Blantyre, Southern Region, MalawiMedical Microbiology, Liverpool University Hospitals NHS Foundation Trust, Liverpool, UKDepartment of Eye and Vision Sciences, University of Liverpool, Liverpool, UKUniversity of Liverpool, Liverpool, UKDepartment of Eye and Vision Sciences, University of Liverpool, Liverpool, UKQueen Elizabeth Central Hospital, Blantyre, Southern Region, MalawiDepartment of Infection Biology and Microbiomes, University of Liverpool, Liverpool, UKQueen Elizabeth Central Hospital, Blantyre, Southern Region, MalawiObjective Microbial keratitis (MK) is a significant cause of blindness in sub-Saharan Africa. We investigated the feasibility of using a novel corneal impression membrane (CIM) for obtaining and processing samples by culture, PCR and whole-genome sequencing (WGS) in patients presenting with suspected MK in Malawi.Methods and analysis Samples were collected from patients presenting with suspected MK using a 12 mm diameter polytetrafluoroethylene CIM disc. Samples were processed using culture and PCR for Acanthamoeba, herpes simplex virus type 1 (HSV-1) and the bacterial 16S rRNA gene. Minimum inhibitory concentrations of isolates to eight antimicrobials were measured using susceptibility strips. WGS was used to characterise Staphylococcus aureus isolates.Results 71 eyes of 71 patients were included. The overall CIM isolation rate was 81.7% (58 positive samples from 71 participants). 69 (81.2%) of isolates were Gram-positive cocci. Coagulase-negative Staphylococcus 31.8% and Streptococcus species 14.1% were the most isolated bacteria. Seven (9.9%) participants were positive for HSV-1. Fungi and Acanthamoeba were not detected. Moxifloxacin and chloramphenicol offered the best coverage for both Gram-positive and Gram-negative isolates when susceptibility was determined using known antimicrobial first quartile concentrations and European Committee on Antimicrobial Susceptibility Testing breakpoints, respectively. WGS identified known virulence genes associated with S. aureus keratitis.Conclusions In a resource-poor setting, a CIM can be used to safely sample the cornea in patients presenting with suspected MK, enabling identification of causative microorganisms by culture and PCR. Although the microbiological spectrum found was limited to the dry season, these preliminary results could be used to guide empirical treatment.https://bmjophth.bmj.com/content/9/1/e001682.full |
| spellingShingle | Timothy Neal Dean Everett Stephen B Kaye Alistair Darby Moira Gandiwa Shaffi Mdala Caroline E Corless Rose Herbert Nicholas A V Beare Tobi F Somerville Thokozani Zungu Malcolm J Horsburgh Petros C Kayange Microbial keratitis in Southern Malawi: a microbiological pilot study BMJ Open Ophthalmology |
| title | Microbial keratitis in Southern Malawi: a microbiological pilot study |
| title_full | Microbial keratitis in Southern Malawi: a microbiological pilot study |
| title_fullStr | Microbial keratitis in Southern Malawi: a microbiological pilot study |
| title_full_unstemmed | Microbial keratitis in Southern Malawi: a microbiological pilot study |
| title_short | Microbial keratitis in Southern Malawi: a microbiological pilot study |
| title_sort | microbial keratitis in southern malawi a microbiological pilot study |
| url | https://bmjophth.bmj.com/content/9/1/e001682.full |
| work_keys_str_mv | AT timothyneal microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT deaneverett microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT stephenbkaye microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT alistairdarby microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT moiragandiwa microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT shaffimdala microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT carolineecorless microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT roseherbert microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT nicholasavbeare microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT tobifsomerville microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT thokozanizungu microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT malcolmjhorsburgh microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy AT petrosckayange microbialkeratitisinsouthernmalawiamicrobiologicalpilotstudy |