A 7-year review of clinical characteristics, predisposing factors and outcomes of post-keratoplasty infectious keratitis: the Nottingham infectious keratitis study

Background/objectives

Post-keratoplasty infectious keratitis (PKIK) is a unique sight-threatening clinical entity which often poses significant therapeutic challenges. This study aimed to examine the clinical presentation, risk factors, management, and clinical outcomes of PKIK.

Methods

This was a retrospective study of all patients who presented to the Queen's Medical Centre, Nottingham, with PKIK between September 2015 and August 2022 (a 7-year period). Relevant data on types of keratoplasty, clinical presentations, causative microorganisms, management, and outcome were analyzed.

Results

Forty-nine PKIK cases, including four cases of interface infectious keratitis, were identified during the study period. The most common graft indications for PKP, DALK and EK were failed grafts (9, 37.5%), keratoconus (6, 54.5%) and Fuchs endothelial corneal dystrophy (FECD; 8, 57.1%), respectively. Staphylococcus spp. were the most commonly identified organisms (15, 50.0%). Bullous keratopathy (18, 36.7%), ocular surface disease (18, 36.7%), and broken/loose sutures (15, 30.6%) were the most common risk factors. Concurrent use of topical steroids was identified in 25 (51.0%) cases. Of 31 functioning grafts at presentation, 12 (38.7%) grafts failed at final follow-up with 15 (48.4%) patients retaining a CDVA of ≥1.0 logMAR. The overall estimated 5-year survival rate post-PKIK was 55.9% (95% CI, 35.9%-75.9%), with DALK having the highest survival rate [63.6% (95% CI, 28.9%-98.3%)], followed by EK [57.1% (95% CI, 20.4%-93.8%)] and PKP [52.7% (95% CI, 25.1%-80.3%)], though no statistical difference was observed (p=0.48).

Conclusions

PKIK represents an important cause of IK and graft failure. Bullous keratopathy, OSD and suture-related complications are the commonest risk factors, highlighting the potential benefit of prophylactic topical antibiotics (for unhealthy ocular surface) and early suture removal (where possible) in reducing the risk of PKIK. Graft survival may be higher in lamellar keratoplasty following PKIK but larger studies are required to elucidate this observation.

Multidrug-Resistant ESBL-Producing E. coli in Clinical Samples from the UK

Globally, cephalosporin therapy failure is a serious problem for infection control. One causative agent of cephalosporin-resistant infections is multidrug-resistant (MDR) E. coli producing extended-spectrum β-lactamases (ESBLs) and/or plasmid-encoded AmpC (pAmpC) β-lactamases. We evaluated the occurrence of ESBL/pAmpC genetic determinants in phenotypically MDR E. coli isolated from clinical samples of blood, faeces, ear effusion, urine and sputum from a UK hospital. Phenotypic resistance profiling for 18 antibiotics (from seven classes) showed that 32/35 isolates were MDR, with resistance to 4-16 of the tested antibiotics. Of the isolates, 97.1% showed resistance to ampicillin, 71.4% showed resistance to co-amoxiclav, cefotaxime, ceftazidime and ceftiofur, and 68.5% showed resistance to cefquinome. bla_CTX-M, bla_TEM and bla_OXA-1 genes were detected in 23, 13 and 12 strains, respectively, and Intl1 was detected in 17 isolates. The most common subtypes among the definite sequence types were CTX-M-15 (40%) and TEM-1 (75%). No E. coli isolates carried pAmpC genes. Significant correlations were seen between CTX-M carriage and cefotaxime, ceftiofur, aztreonam, ceftazidime and cefquinome resistance; between bla_CTX-M, bla_TEM and bla_OXA-1 carriage and ciprofloxacin resistance; and between Intl1 carriage and trimethoprim/sulfamethoxazole resistance. Thus, MDR phenotypes may be conferred by a relatively small number of genes. The level and pattern of antibiotic resistance highlight the need for better antibiotic therapy guidelines, including reduced use and improved surveillance.

P43 In vitro activity of cefiderocol and comparators against Gram-negative pathogens: ARTEMIS study in the UK

Objectives

Cefiderocol (CFDC) is a novel siderophore cephalosporin approved in Europe for the treatment of infections caused by aerobic Gram-negative (GN) bacteria in adults with limited treatment options. The aim of the ARTEMIS study was to evaluate the in vitro activity of CFDC and comparators against recent clinical isolates collected across five countries in Europe. Here we report susceptibility data from isolates collected in the UK.

Methods

From January to December 2020, GN clinical isolates were collected from hospitalized patients from all infection sites (excluding the urinary tract). Duplicate isolates of the same species from a single patient were excluded. As a prespecified target, each laboratory collected 75 isolates, with: 20 Klebsiella spp., 20 other Enterobacterales, 20 Pseudomonas aeruginosa and 15 Acinetobacter baumannii isolates expected to be included. CFDC susceptibility testing was conducted using disc diffusion (with 30 μg discs) on Mueller–Hinton agar and Sensititre^™ broth microdilution (BMD) panels [EUMDROXF; centrally tested at International Health Management Associates (IHMA)]. Susceptibility by disc diffusion was reported using zone diameter breakpoints (BPs) of ≥22 mm (or ≥17 mm for A. baumannii isolates, corresponding to MIC values below the pharmacokinetic/pharmacodynamic BPs of ≤2 mg/L). Comparator susceptibility was determined using custom research use only Sensititre^™ BMD panels (CMP2SHIH) according to the EUCAST method for BMD. Antimicrobial susceptibility was interpreted according to EUCAST clinical BPs (v.11 2021).

Results

In total, 517 isolates were collected from nine UK hospitals, of which: 308 (59.6%) were Enterobacterales [including 147 (28.4%) Klebsiella spp.], 148 (28.6%) were P. aeruginosa and 33 (6.4%) were A. baumannii. The most common sites of infection were bloodstream (n = 245; 47.4%), respiratory tract (n = 158; 30.6%) and skin (n = 59; 11.4%). A high percentage of Enterobacterales (90.2%), P. aeruginosa (96.6%) and A. baumannii (96.9%) isolates were susceptible to CFDC by disc diffusion. By central laboratory testing (MIC), 99.0% of Enterobacterales, 99.3% of P. aeruginosa and 93.9% of A. baumannii isolates were susceptible to CFDC. High susceptibility rates (>85%) were also observed for all comparator agents (Table 1). A total of 32/517 (6.2%) isolates were carbapenem resistant, the majority of which (22/32, 68.8%) were susceptible to CFDC by disc diffusion.

Conclusions

Among clinical GN isolates collected from UK hospitals in 2020, a high percentage (98.6%), including carbapenem-resistant isolates, were susceptible to CFDC by BMD. These data support the use of CFDC in patients with GN infections and limited treatment options. The differences identified between EUCAST disc diffusion and BMD using Sensititre^™ panels for CFDC highlight that disc diffusion underestimates Enterobacterales susceptibility to CFDC, which is mainly a result of the area of technical uncertainty (where isolates with MIC of 2 mg/L have a zone diameter of <22 mm and are characterized as resistant). This requires further investigation to explore whether the EUCAST zone diameter BP is optimal for CFDC disc testing.

Psychrobacter piechaudii shunt infection: first report of human infection

Psychrobacter piechaudii is a recently described species of Gram-negative bacteria in the Moraxellaceae family. No cases of human infection due to this species have been described before. We report the case of an ex-premature infant girl with hydrocephalus secondary to intraventricular haemorrhage who underwent multiple cerebrospinal fluid (CSF) shunt operations. She ultimately developed Psychrobacter piechaudii meningitis, presenting as ventriculoperitoneal shunt dysfunction and wound leak, which necessitated removal of the shunt, a period of external ventricular drainage and antibiotics. We found this organism to be sensitive to intravenous ceftazidime (50 mg/kg) and ciprofloxacin, and a 7-10 day treatment course prior to shunt re-insertion (and 3 week total course) was sufficient. The patient is well post-operatively. To the best of our knowledge, this is the first reported case of Psychrobacter piechaudii infection in a human.

Risk Factors, Clinical Outcomes, and Prognostic Factors of Bacterial Keratitis: The Nottingham Infectious Keratitis Study

Background/Aim: To examine the risk factors, clinical characteristics, outcomes, and prognostic factors of bacterial keratitis (BK) in Nottingham, UK.

Methods: This was a retrospective study of patients who presented to the Queen's Medical Centre, Nottingham, with suspected BK during 2015–2019. Relevant data, including the demographic factors, risk factors, clinical outcomes, and potential prognostic factors, were analysed.

Results: A total of 283 patients (n = 283 eyes) were included; mean age was 54.4 ± 21.0 years and 50.9% were male. Of 283 cases, 128 (45.2%) cases were culture-positive. Relevant risk factors were identified in 96.5% patients, with ocular surface diseases (47.3%), contact lens wear (35.3%) and systemic immunosuppression (18.4%) being the most common factors. Contact lens wear was most commonly associated with P. aeruginosa whereas Staphylococci spp. were most commonly implicated in non-contact lens-related BK cases (p = 0.017). At presentation, culture-positive cases were associated with older age, worse presenting corrected-distance-visual-acuity (CDVA), use of topical corticosteroids, larger epithelial defect and infiltrate, central location and hypopyon (all p < 0.01), when compared to culture-negative cases. Hospitalisation was required in 57.2% patients, with a mean length of stay of 8.0 ± 8.3 days. Surgical intervention was required in 16.3% patients. Significant complications such as threatened/actual corneal perforation (8.8%), loss of perception of light vision (3.9%), and evisceration/enucleation (1.4%) were noted. Poor visual outcome (final corrected-distance-visual-acuity of <0.6 logMAR) and delayed corneal healing (>30 days from initial presentation) were significantly affected by age >50 years, infiltrate size >3 mm, and reduced presenting vision (all p < 0.05).

Conclusion: BK represents a significant ocular morbidity in the UK, with ocular surface diseases, contact lens wear, and systemic immunosuppression being the main risk factors. Older age, large infiltrate, and poor presenting vision were predictive of poor visual outcome and delayed corneal healing, highlighting the importance of prevention and early intervention for BK.

Comparative effects of viral-transport-medium heat inactivation upon downstream SARS-CoV-2 detection in patient samples

Introduction

The COVID-19 pandemic, which began in 2020 is testing economic resilience and surge capacity of healthcare providers worldwide. At the time of writing, positive detection of the SARS-CoV-2 virus remains the only method for diagnosing COVID-19 infection. Rapid upscaling of national SARS-CoV-2 genome testing presented challenges: (1) Unpredictable supply chains of reagents and kits for virus inactivation, RNA extraction and PCR-detection of viral genomes. (2) Rapid time to result of <24 h is required in order to facilitate timely infection control measures.

Hypothesis

Extraction-free sample processing would impact commercially available SARS-CoV-2 genome detection methods.

Aim

We evaluated whether alternative commercially available kits provided sensitivity and accuracy of SARS-CoV-2 genome detection comparable to those used by regional National Healthcare Services (NHS).

Methodology

We tested several detection methods and tested whether detection was altered by heat inactivation, an approach for rapid one-step viral inactivation and RNA extraction without chemicals or kits.

Results

Using purified RNA, we found the CerTest VIASURE kit to be comparable to the Altona RealStar system currently in use, and further showed that both diagnostic kits performed similarly in the BioRad CFX96 and Roche LightCycler 480 II machines. Additionally, both kits were comparable to a third alternative using a combination of Quantabio qScript one-step Quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR) mix and Centre for Disease Control and Prevention (CDC)-accredited N1 and N2 primer/probes when looking specifically at borderline samples. Importantly, when using the kits in an extraction-free protocol, following heat inactivation, we saw differing results, with the combined Quantabio-CDC assay showing superior accuracy and sensitivity. In particular, detection using the CDC N2 probe following the extraction-free protocol was highly correlated to results generated with the same probe following RNA extraction and reported clinically (n=127; R²=0.9259).

Conclusion

Our results demonstrate that sample treatment can greatly affect the downstream performance of SARS-CoV-2 diagnostic kits, with varying impact depending on the kit. We also showed that one-step heat-inactivation methods could reduce time from swab receipt to outcome of test result. Combined, these findings present alternatives to the protocols in use and can serve to alleviate any arising supply-chain issues at different points in the workflow, whilst accelerating testing, and reducing cost and environmental impact.

Comparison of culture based methods for the isolation of Clostridium difficile from stool samples in a research setting

Effective isolation of Clostridium difficile from stool samples is important in the research setting, especially where low numbers of spores/vegetative cells may be present within a sample. In this study, three protocols for stool culture were investigated to find a sensitive, cost effective and timely method of C. difficile isolation. For the initial enrichment step, the effectiveness of two different rich media, cycloserine-cefoxitin fructose broth (CCFB) and cycloserine-cefoxitin mannitol broth with taurocholate and lysozyme (CCMB-TAL) were compared. For the comparison of four different, selective solid media; Cycloserine-cefoxitin fructose agar (CCFA), Cycloserine-cefoxitin egg yolk agar (CCEY), ChromID C. difficile and tryptone soy agar (TSA) with 5% sheep's blood with and without preceding broth enrichment were used. As a means to enable differentiation between C. difficile and other fecal flora, the effectiveness of the inclusion of a pH indictor (1% Neutral Red), was also evaluated. The data derived indicated that CCFB is more sensitive than CCMB-TAL, however, the latter had an improved recovery rate. A broth enrichment step had a reduced sensitivity over direct plating. ChromID C. difficile showed the best recovery rate whereas CCEY egg yolk agar was the most sensitive of the four. The addition of 1% Neutral Red did not show sufficient colour change when added to CCEY egg yolk agar to be used as a differential medium. For a low cost, timely and sensitive method of isolating C. difficile from stool samples we recommend direct plating onto CCEY egg yolk agar after heat shock.

An evaluation of the user acceptability of chlorhexidine handwash formulations

Four similar-looking preparations containing 4% chlorhexidine ('Hibiscrub', Surgiscrub', 'Uniscrub', 'Macrocide') were compared in a single-blind, randomized study in a group of 73 volunteers. The volunteers washed their hands with each preparation ten times over 9 h, one preparation day-1 on each of four days over two weeks. The acceptability of the agents was assessed using visual analogue scales which were analysed by paired t-test. There were marked differences between the products. 'Uniscrub' smelled worse (P less than 0.003) and felt worse than the others (P less than 0.003). 'Hibiscrub' lathered well but 'Macrocide' was found easiest to rinse off. 'Hibiscrub' and 'Surgiscrub' were the least irritant and had the best visual appearance. Despite apparent similarities, these chlorhexidine formulations varied in acceptability to users.

Treatment of congenital ptosis by maximal levator resection

The treatment of severe congenital ptosis may include frontalis suspension or maximal levator resection. A previous study of 145 consecutive frontalis suspensions for congenital ptosis showed a fairly high recurrence rate, frequent granuloma formation, and significant brow scars. In 28 patients undergoing 32 maximal levator resections utilizing our technique, 28 patients had excellent results. Two required reoperations and two additional patients had undercorrections that did not warrant reoperation. There were no significant complications. We believe that maximal levator resection is a better surgical alternative than frontalis suspension in the treatment of severe congenital ptosis whether unilateral or bilateral. In our experience, maximal levator resection provides a better cosmetic result and the recurrence rate is probably less than with frontalis suspension.