BackgroundThe selection of an appropriate antimicrobial is a challenging task for clinicians. The Kirby-Bauer disk diffusion method is one of the most widely practiced antimicrobial susceptibility tests (AST). It is affected by many factors among which are the media used. Mueller-Hinton agar (MHA) is the standard medium recommended in guidelines. However, these guidelines are not strictly adhered to in some developing countries.ObjectivesValidation of AST results on nutrient agar (NA) medium used as a substitute for MHA by some microbiology laboratories in Alexandria, Egypt.MethodsA total of 149 clinical bacterial isolates and 3 reference strains: Staphylococcus aureus (S. aureus) ATCC® 25923, Escherichia coli (E. coli) ATCC®25922, and Pseudomonas aeruginosa (P. aeruginosa) ATCC®27853 were comparatively challenged to antibiotics employing MHA and NA.ResultsAll antibiotics-reference bacterial strain challenges on NA compared to MHA were unacceptable (> 3 out of limit zones in 30 consecutive days). Considering clinical isolates, the frequency of very major, major, and minor errors on NA was highest in the case of P. aeruginosa (8.98%, 4.08%, and 14.7% respectively) followed by S. aureus (7.6%, 6%, and 8.8% respectively). On the other hand, the least frequency of errors was in the case of Enterobacteriaceae (0%, 0.4%, and 3.2% respectively).Conclusions and recommendationsUsing NA in AST resulted in multiple errors and the high discrepancy in results compared to MHA making it unreliable for susceptibility testing. MHA should not be replaced by NA in AST. Following guidelines and QC measures for AST must be neither bypassed nor underestimated.

ObjectivesAdults with congenital heart disease (ACHD) are a growing group with end-stage heart failure. We aim to describe the outcomes of ACHD patients undergoing assessment for orthotopic heart transplant (OHT).MethodsCase notes of consecutive ACHD patients (>16 years) assessed for OHT between 2000 and 2016 at our centre were reviewed. Decision and outcome were reported as of 2017. Data were analysed in three groups: systemic left ventricle (LV), systemic right ventricle (RV) and single ventricle (SV).Results196 patients were assessed (31.8 years, 27% LV, 29% RV, 44% SV). 89 (45%) patients were listed for OHT and 67 (34%) were transplanted. 41 (21%) were unsuitable or too high risk and 36 (18%) were too well for listing. Conventional surgery was undertaken in 13 (7%) and ventricular assist device in 17 (9%) with 7 (4%) bridged to candidacy. Survival from assessment was 84.2% at 1 year and 69.7% at 5 years, with no difference between groups. Patients who were considered unsuitable for OHT (HR 11.199, p<0.001) and listed (HR 3.792, p=0.030) were more likely to die than those who were considered too well. Assessments increased over the study period.ConclusionsThe number of ACHD patients assessed for OHT is increasing. A third are transplanted with a small number receiving conventional surgery. Those who are unsuitable have a poor prognosis.

The single ventricle patient population comprises the most complex cohort presenting to the cardiac transplant team, in terms of demographics, anatomic substrate, and unique physiology. It is also the most rapidly growing diagnostic group presenting for heart transplantation. In this manuscript, we aim to describe the changing landscape of transplantation in single ventricle conditions through reflection on our own institution's practice and experience, alongside contemporary literature review. Single ventricle patients are heterogeneous in terms of age, anatomic diagnosis and physiology according to surgical stage of repair.Progress in surgical palliative strategies has impacted upon the present composition of the population, with growing numbers of hypoplastic left heart syndrome patients and those with late physiology failure following Fontan completion. Multiple prior surgeries, immunological sensitivity and multi-organ involvement impart high peri-operative risk but can be mitigated in part by careful pre-operative planning by a dedicated multidisciplinary team addressing issues such as planning of concurrent reconstructive surgery, minimizing the post-operative effect of collaterals, timely harvesting, oversizing of donor organs to minimize graft failure, and strategies to address anticipated post-operative elevation in pulmonary vascular resistance. Determining optimal timing for transplant in these patients remains unclear, but understanding the risk of alternative surgical options can help guide decision making with regards to listing.