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A 3‐year‐old male neutered Golden Retriever with nasal swelling and lymphadenopathy was diagnosed with diffuse Mycobacterium avium infection. Treatment with 9 months of enrofloxacin, clarithromycin and rifampicin was successful, but relapsed 10 months later with lymphadenopathy, skin plaques and testicular involvement. Repeat treatment for 12 months was effective but 15 months later a second relapse responded to the same therapy which is ongoing with survival from diagnosis of 82 months. A 1‐year‐old male neutered Portuguese Podengo was diagnosed with polyarthritis and M. avium infection and treated with enrofloxacin, clarithromycin and rifampicin for 4 months but relapsed, subsequently responding to combined pradofloxacin, rifampicin, doxycycline and ethambutol. After 12 months of treatment, M. avium was detected and treatment extended to 17 months before stopping when no organism was detected. Relapse occurred after 6 weeks, responding to retreatment but relapsing (polyarthropathy, lymphadenomegaly) after 15 months, with euthanasia 38 months after diagnosis. Dogs with M. avium are challenging to treat with frequent relapse; however, long‐term survival is possible. [ABSTRACT FROM AUTHOR]

Discusses the evaluation of the usefulness of multimedia materials in medical education. Approaches the issue by looking at the nature of the knowledge that medical professionals are expected to acquire and relating that knowledge to what multimedia applications have to offer. Multimedia applications must also be analyzed for whether they can assist the novice in moving through stages of increasing competence. (PVD)

A 1‐year‐old male neutered Portuguese Podengo dog was presented for lameness, inappetence, pyrexia, diarrhoea and abdominal moderate to severe lymphadenomegaly. Cytology of synovial fluid revealed neutrophilic inflammation in multiple joints suggestive of immune‐mediated polyarthritis. Cytology of fine‐needle‐aspiration material obtained from lymph nodes revealed macrophages with intracytoplasmic, rod‐like Ziehl‐Neelsen positive staining structures, indicative of mycobacteria. Four‐month treatment with enrofloxacin, rifampicin and clarithromycin resulted in clinical improvement and resolution of polyarthritis as evidenced on repeat synoviocentesis, but diarrhoea recurred, Ziehl‐Neelsen positive organisms were again found on lymph node cytology and analysis of the 16S rRNA‐gene using the Basic Local Alignment Search Tool facility resulted in a match to Mycobacterium avium with 100% sequence identity. Treatment was adjusted to include pradofloxacin, doxycycline, rifampicin and ethambutol and 3 months later the dog is clinically normal. Based on the literature search, this is the first time canine Mycobacterium avium infection associated with immune‐mediated polyarthritis is reported. Based on scoping searches, this is the first report of canine Mycobacterium avium infection associated with immune‐mediated polyarthritis. [ABSTRACT FROM AUTHOR]

To assess the relationship between endomyocardial biopsy (EMB) utilizing histopathology (Hx) and the molecular microscope diagnostic system (MMDx) with donor-derived cell-free DNA (ddcfDNA) in pediatric heart transplant (PHT) recipients. PHT recipients undergoing routine or for-cause EMB to assess acute rejection (AR) had ddcfDNA drawn within 1 week prior to EMB. DdcfDNA samples were compared to Hx (acute cellular rejection ≥ 2R, antibody mediated rejection ≥ pAMR2) and MMDx for AR (antibody mediated rejection = ABMR, T-cell mediated rejection = TCMR, mixed = features of both) and degree of injury. Concordance of MMDx and Hx results were compared using Cohen's kappa statistic and comparison of ddcfDNA and EMB results were performed using Wilcoxon Rank-Sum and Kruskal-Wallis tests, as appropriate. A total of 55 paired EMB and ddcfDNA samples were obtained from 48 patients over a 6-month period. Patients were a median of 39 months (IQR 15-81 months) post-transplant. Hx was normal in 37 (67%) and MMDx was normal in 31 (55%) of EMB. The remaining 24 MMDx had injury pattern with variable types of AR - 10 (42%) ABMR, 3 (13%) TCMR, 1 (4%) mixed AR, and 10 (42%) with injury alone. Of the EMB with normal Hx, 18 (49%) had abnormal MMDx (8 ABMR, 3 TCMR, 1 mixed, 6 injury) and 14 (78%) of these had an associated elevated ddcfDNA (0.48 [0.24-0.82]%). There was no significant difference in ddcfDNA values between samples with AR vs no AR on Hx (0.17 [0.12-0.46%] vs 0.12 [0.12-0.17%], p=0.3) in the setting of few abnormal Hx samples. However, presence of AR on MMDx was associated with higher ddcfDNA levels (0.54 [0.38-1.5] vs 0.12 [0.12-0.24], p<0.001). When stratified by type of AR, ddcfDNA values were highest in EMB with ABMR (normal: 0.12 [0.12-0.17], TCMR: 0.32 [0.12-0.38], ABMR: 0.67 [0.45-4.3], injury only: 0.29 [0.12-0.54], p<0.001). Presence of injury on MMDx was also associated with higher ddcfDNA levels (injury - 0.43 [0.21-1.16] vs no injury - 0.12 [0.12-0.17], p<0.001). MMDx identifies AR in nearly half of samples read as "normal" on Hx. Elevated ddcfDNA is associated with AR on MMDx as well as injury pattern. ABMR on MMDx is associated with the highest ddcfDNA levels. A combination of Hx, MMDx, and ddcfDNA is likely to yield the highest sensitivity when screening for graft rejection in PHT recipients. [ABSTRACT FROM AUTHOR]

To describe the relationship between the molecular microscope diagnostic system (MMDx) and histopathology (Hx) for acute rejection (AR) in pediatric heart transplantation (PHT). Secondarily, to describe the feasibility of splitting endomyocardial biopsies (EMBs) to assay MMDx and Hx while minimizing the total tissue collected. Single center review of EMBs from PHT recipients sent for MMDx (2 samples) and Hx (4 samples) from 11/2021-9/2022. Six EMBs or 4 EBMs (2 split for MMDx and Hx) were obtained at the discretion of the interventionalist. The presence of acute cellular rejection (ACR, ≥ 1R/1B) or antibody mediated rejection (AMR, ≥ pAMR1) by Hx and MMDx were compared for agreement among the overall cohort and unique vs split samples. Agreement was evaluated using Cohen's Kappa statistic, and split vs unique sample results were compared using chi-squared test. 115 EMBs in 70 patients were analyzed - 51 split, 40 unique, and 24 mixed or unknown. Twenty six (23%) had AR by Hx, 36 (31%) had AR by MMDx, and 69 (20%) were negative by both methods (Fig 1). There was fair agreement between MMDx and Hx for presence of ACR (103 concordant, 11 discordant, k=0.37, p<0.001) and AMR (86 concordant, 26 discordant, k=0.27, p=0.003). Nineteen samples (21%) with normal Hx had AR on MMDx (15 AMR, 3 ACR, 1 mixed). Twenty-one samples (18%) revealed injury without AR by MMDx (5 AMR, 1 ACR, and 15 no rejection by Hx). There was no difference in Hx and MMDx concordance between split or unique EMBs (p = 0.40). All split samples resulted in an adequate tissue quantity for analysis. In PHT, MMDx displays fair agreement with Hx with regards to absence or presence of AR, and a portion of samples with negative Hx had AR by MMDx. Splitting EMBs does not affect results and allows for molecular and histopathologic assessment of AR while minimizing tissue mass collected. [ABSTRACT FROM AUTHOR]