Aims: To evaluate the performance of two matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry platforms to identify molds isolated from clinical specimens. Methods: Fifty mo... Plain language summary There are two different mass spectrometry systems that can be used in the hospital laboratory to find out what kind of mold is growing from a patient sample: the Vitek® MS an...

Aspergillosis is a commonly diagnosed fungal infection. Histopathologic examination alone can have diagnostic pitfalls due to the overlapping of fungal morphology. We report a case of Scedosporium boydii infection initially misdiagnosed as aspergillosis. The patient presented to the hospital with shortness of breath and chest and abdominal pain. Laboratory tests revealed leukocytosis and elevated serum liver enzymes, myoglobin and lipase. He died of hypotensive shock and brain abscesses despite antibiotic treatment. Autopsy revealed invasive fungal infection in the heart, thyroid, and brain with presence of 45-degree angled, branching hyphae. The initial diagnosis of aspergillosis was made; however, further molecular studies identified the organism as S. boydii. This report reveals the potential pitfalls of morphologic diagnosis alone; and the necessity of other testing modalities to render an accurate diagnosis which is crucial for appropriate.

BK polyomavirus (BKPyV) quantification is useful for monitoring renal transplant patient response to therapy. The Abbott m2000 RealTime System employed by some clinical laboratories to perform US Food and Drug Administration-approved assays can also be used to develop in-house assays such as the one presented here. This study aimed to validate an in-house quantitative real-time PCR assay targeting the BKPyV major capsid VP1 gene for assessment of viral load using the Abbott m2000 RealTime System. BKPyV load was measured in 95 urine and plasma samples previously tested for BKPyV by one of three laboratories (46 BKPyV-positive samples consisting of 35 plasma and 11 urine samples; 49 samples negative for BKPyV consisting of 47 plasma and two urine samples). Two additional plasma specimens from the College of American Pathologists proficiency testing survey were also analysed. Precision studies were performed by diluting a high-viral-titre patient sample into BKPyV-negative pooled plasma to create high-positive (6.16 log₁₀ copies ml⁻¹) and low-positive (3.16 log₁₀ copies ml⁻¹) samples. For precision studies of inter-assay variability, a high-positive (7.0 log₁₀ copies ml⁻¹) and a low-positive (3.0 log₁₀ copies ml⁻¹) sample were measured in 20 separate runs. The assay’s limit of quantification and limit of detection were 2.70 and 2.25 log₁₀ copies ml⁻¹, respectively. The assay was linear from 2.70 to 9.26 log₁₀ copies ml⁻¹. Of the 48 known positives, 43 were detected as positive, with three reported by the reference laboratory as values lower than the limit of detection. Two known positives at 3.27 and 3.80 log₁₀ copies ml⁻¹ tested negative by the m2000 BKPyV assay. Of the 49 known negative samples, 48 were negative by the m2000 BKPyV load assay, with one sample confirmed positive by a reference laboratory. Qualitative analysis prior to discrepancy testing demonstrated a sensitivity of 89.58 % and a specificity of 97.96 %. Precision studies demonstrated inter-assay coefficients of variation of 0.63 % (high positive) and 4.38 % (low positive). Genotyping was performed on 22 patient samples, of which 21 (95.45 %) were type I and one (4.55 %) was type II. In conclusion, the m2000 BKPyV viral load assay sensitivity, specificity, linear range, precision and cost effectiveness make it an attractive methodology for clinical laboratories using the Abbott m2000 RealTime System.

We report a case of a rapidly fatal postlaparoscopic cholecystectomy liver infection from the rarely isolated species Clostridium butyricum. Liver examination at autopsy showed cystic spaces, necrosis, and spore-forming Gram-positive rods. 16sRNA gene sequencing of the cystic liver tissue identified the organism as C. butyricum.

Background: Except for their role in bacterial endocarditis, nonpneumococcal Streptococcus mitis group (SMG) bacteria have traditionally been regarded as commensals of the oropharynx. Widespread adoption of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry has increased identification of these organisms and has led to increased concern about their clinical significance. We evaluated SMG bacteremia in a large multicenter cohort to characterize associated clinical syndromes and better define their clinical relevance. Methods: We performed a retrospective review of all adult patients from 2017 to 2025 who had SMG bacteremia at 3 hospitals within the Texas Medical Center. SMG bacteremia was defined as isolation of S mitis, S mitis/oralis, or S mitis group as determined by MALDI-TOF. Clinical syndromes were identified through chart review and assigned using consistent classification approaches informed by physician documentation, imaging, and microbiologic data. Results: Among 253 patients, neutropenia-associated bacteremia was most common (29.6%), followed by pneumonia (9.5%), infective endocarditis (8.7%), skin, soft tissue, or bone infections (7.9%), and other identified sources (12%). No clear source was identified in 9.5% of cases. Only 22.9% were classified as contaminants. High-grade bacteremia was common, with 47% of cases having ≥3 positive blood culture bottles. In contrast, patients in whom SMG was regarded as contaminant nearly always had only a single-bottle positive. Conclusions: Streptococcus mitis group bacteremia was associated with a broad spectrum of clinical syndromes, with most isolates being regarded as representing clinically significant infection.

Background: The Mycobacterium avium-intracellulare complex (MAC) consists of two mycobacterial species- M.avium and M. intracellulare. The organisms exist in nature in water, soil, and food and can be acquired via inhalation or ingestion. It is an uncommon cause of infection, initially affecting the pulmonary system in patients with underlying lung disease or immunocompromised patients. Extra-pulmonary infection can occur in the liver, spleen, skin, soft tissue, and lymph nodes. Only ten cases in the English literature have documented central nervous system (CNS) infections. Additionally, these eight cases were reported in HIV positive patients who presented with single or multiple enhancing brain lesions and were initially misdiagnosed as toxoplasmosis. Case presentation: We report a case of a 45-year-old male who was diagnosed with HIV/ AIDS and was found to have four parietal and temporal ring-enhancing lesions by MRI that failed to improve on anti-Toxoplasmosis therapy. A brain biopsy demonstrated multiple nodular granulomata with lymphoplasmacytic cells, epithelioid histiocytes, and rare giant cells. No caseous necrosis is seen, but foci of micronecrosis were present. No toxoplasmosis or primary CNS lymphoma was present. Very abundant acid-fast bacilli were seen on Fite and auramine stains. In addition, there was heavy CD8⁺ T cell infiltration suggestive of Immune Reconstitution Inflammatory Syndrome (IRIS). PCR and sequencing of paraffin-embedded brain tissue demonstrated M. avium. He was treated with Rifampin, Isoniazid, Pyrazinamide and Ethambutol (RIPE) plus clarithromycin 500 mg BID that was switched to azithromycin 500 mg to decrease QTc prolongation. He is also now on anti-retroviral therapy. At the last clinic visit approximately five months after diagnosis of CNS MAC, he was very much improved.Conclusion: Brain MAC abscess is very rare, with less than 10 cases being previously reported in both AIDS and non-AIDS patients. This diagnosis should be considered in immunocompromised patients who do not respond to anti-toxoplasmosis therapy and brain biopsy is important to provide definitive identification and guide treatment.