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Diagnostic tools that can rapidly identify and characterize microbes growing in blood cultures are important components of clinical microbiology practice because they help to provide timely information that can be used to optimize patient management. This publication describes the bioMérieux BIOFIRE Blood Culture Identification 2 (BCID2) Panel clinical study that was submitted to the U.S.

Antimicrobial susceptibility testing (AST) in RPMI 1640, a more physiologically relevant culture medium, revealed that a substantial proportion of carbapenem-resistant Acinetobacter baumannii isolates were susceptible to azithromycin, a macrolide antibiotic not currently considered effective against A. baumannii . Experiments using Galleria mellonella validated these in vitro data.

Antimicrobial susceptibility testing (AST) in RPMI 1640, a more physiologically relevant culture medium, revealed that a substantial proportion of carbapenem-resistant Acinetobacter baumannii isolates were susceptible to azithromycin, a macrolide antibiotic not currently considered effective against A. baumannii. Experiments using Galleria mellonella validated these

Background In the diagnosis of SARS-COV-2, upper respiratory tract specimens are primarily used for PCR testing. This study aims to evaluate the clinical and diagnostic role of bronchoalveolar lavage (BAL) in diagnosing and managing COVID-19. Methods Patients admitted to Keck Medical Center (Los Angeles, CA) during March 2020-May 2021 who had SARS-CoV-2 PCR tested on both nasopharyngeal swab (NPS) and BAL specimens (QIAGEN QIAstat-Dx RP) were included. Four patient groups were designated by PCR results: (A) NPS+/BAL+ (n=34), (B) NPS+/BAL- (n=26), (C) NPS-/BAL+ (n=5), (D) NPS-/BAL- (n=89). Clinical and laboratory data were retrospectively reviewed. Statistical analysis included the use of one-way ANOVA with Tukey HSD and Fisher’s exact test. Results 154 inpatients had NPS and BAL tested for SARS-CoV-2 RNA (mean age 55.1 y, 59.6% male). BAL was performed mainly to further assess abnormal respiratory function (n=43) or chest imaging findings (n=27), or for COVID-19 work-up (n=17). Mean turnaround time for BAL PCR was 4 h 5 min. Ct values, available on 28 BAL+ samples, did not significantly differ between patients who died (mean Ct 29.9, n=18) vs. survived (mean Ct 28.7, n=10). Time from symptom onset to BAL was significantly longer in Group B (34.2 d) vs. D (13.7 d, p< 0.01) or C (12.8 d, p< 0.05) but not vs. A (23.9 d). Groups did not differ significantly in patient comorbidities, mortality, length of hospital stay, or immunosuppressive status. SARS-CoV-2 NPS+/BAL+ patients were more likely to have diffuse or bilateral chest radiographic opacities (p< 0.01), respiratory culture with Aspergillus spp. (p< 0.05), and ARDS diagnosis than those who were NPS+/BAL- (p< 0.01). Conclusion BALs were an important specimen source for the detection of SARS-CoV-2 in the lower respiratory tract particularly when NPS at admission was PCR-negative and for ruling out COVID-19 pneumonia as a cause of abnormal pulmonary findings or declining respiratory status. BAL positivity for SARS-CoV-2 RNA was associated with higher frequency of diffuse or bilateral opacities on CXR, culture recovery of Aspergillus spp., and ARDS. Ct values of BAL+ samples did not predict mortality though sample size was limited. Further studies on the role of viral detection in BALs in patient management and prognosis are warranted. Disclosures All Authors: No reported disclosures.

Background Antimicrobial resistance (AMR) is a pressing global challenge detected by antimicrobial susceptibility testing (AST) performed by clinical laboratories. AST results are interpreted using clinical breakpoints, which are updated to enable accurate detection of new and emerging AMR. Laboratories that do not apply up-to-date breakpoints impede global efforts to address the AMR crisis, but the extent of this practice is poorly understood. Methods A total of 1490 clinical laboratories participating in a College of American Pathologists proficiency testing survey for bacterial cultures were queried to determine use of obsolete breakpoints. Results Between 37.9% and 70.5% of US laboratories reported using obsolete breakpoints for the antimicrobials that were queried. In contrast, only 17.7%–43.7% of international laboratories reported using obsolete breakpoints (P Conclusions These data demonstrate a significant gap in the ability to detect AMR in the US, and to a lesser extent internationally. Improved application of current breakpoints by clinical laboratories will require combined action from regulatory agencies, laboratory accreditation groups, and device manufacturers.

Background Syndromic PCR testing for lower respiratory pathogens may give rapid, actionable results to aid in management decisions for suspected pneumonia cases. We sought to evaluate the performance of a multiplexed PCR pneumonia panel compared to routine microbiologic work-up in a tertiary care patient population. Methods Sputum and bronchoalveolar lavage (BAL) samples from Keck Medical Center (Los Angeles, CA) inpatients submitted for clinical microbiology work-up Dec 2019-Jun 2020 were tested by a multiplexed PCR panel (FilmArray Pneumonia Panel, BioFire Diagnostics). We compared panel results for typical bacterial pathogens to those of quantitative culture and susceptibility testing. We retrospectively determined the incidence of non-panel respiratory pathogens as detected by standard of care tests in this patient cohort. Results 68 of 180 samples yielded 80 positive bacterial PCR results: 34 were detected by both PCR panel and culture and 46 by PCR panel only, yielding a sensitivity of 100% (34/34) for pathogens detected and specificity of 73.1% (114/156) among negative cultures (normal flora or no growth). Concordant results had PCR Bin values ≥10^5 copies/mL whereas all 18 targets detected at 10^4 copies/mL were culture-negative. Among resistance gene targets, the panel detected 12 MRSA specimens, of which MRSA grew in only 4 cultures; E. coli and CTX-M in 1 specimen from which grew normal flora; and multiple gram-negative organisms and KPC in 1 specimen from which culture isolated carbapenem-resistant P. aeruginosa. Quantitation from positive BAL cultures (n=25) correlated weakly with PCR Bin values (R-squared=0.17). Non-PCR panel pathogens were detected in 22 of 180 (12.2%) specimens through routine methods (16 molds, 3 AFB, and 3 non-fermenter gram-negative bacteria). Conclusion The pneumonia panel had excellent sensitivity for its target bacterial pathogens, but results were often positive in negative cultures. This could be due to antecedent antibiotic therapy, differences in reporting threshold versus culture, or inability of PCR to discern results from normal flora. Non-panel pathogens were detected in a significant proportion in our population. The pneumonia panel should be implemented and interpreted carefully with consideration of antimicrobial stewardship. Disclosures All Authors: No reported disclosures

Cryptococcal infections are an important cause of morbidity and mortality in solid organ transplant patients. Here, we review the microbiology, epidemiology, clinical course, treatment, and outcomes of Cryptococcus in solid organ transplant recipients.We identify the unique findings in solid organ transplant patients when compared to other immunocompromised patients such as those with HIV. We also describe our experience and outcomes with regard to solid organ transplant patients who do not have positive fungal cultures, but cryptococcal antigen positivity and concern for cryptococcal disease.Our review will highlight the importance of these new diagnostic techniques in those with Cryptococcus and solid organ transplant, which will be the subject of new research.

No more than 11 cases of carcinosarcoma of the liver have been reported in the past 40 years that fulfill the definition of hepatocellular carcinoma combined with differentiated sarcomatous elements. Most cases consist of hepatocellular carcinoma with 1 to 2 heterologous elements. We report a case of a 51-year-old woman with liver carcinosarcoma consisting of 3 carcinomatous components and 4 sarcomatous components. Hepatocellular carcinoma, fibrolamellar type, was accompanied by neuroendocrine carcinoma (neuron-specific enolase and synaptophysin positive) and adenocarcinoma (cytokeratin 7 and 20 positive). The sarcomatous elements consisted of poorly differentiated spindle cell neoplasm (vimentin positive), leiomyosarcoma (smooth muscle actin positive), rhabdomyosarcoma (desmin positive), and osteosarcoma. To our knowledge, this is the first case of liver carcinosarcoma with this many differentiated heterologous features. There are differing views on the pathogenesis of this tumor. Findings in this case support the view that metaplasia of carcinomatous cells gives rise to the sarcomatous elements.

To evaluate the spectrum and antibiotic susceptibility panel of infectious keratitis at a major tertiary care referral eye center and a major county hospital in Southern California.Retrospective case series.All cultured infectious keratitis cases from July 1, 2008, through December 31, 2012, from the Doheny Eye Institute (DEI) and the Los Angeles County + University of Southern California Medical Center (LAC+USC) were evaluated.Microbiology records were reviewed retrospectively.Microbial isolates as well as antibiotic susceptibility patterns were analyzed.One hundred eighty-four (63%) of 290 cases showed positive culture results at DEI and 152 (82%) of 186 cases showed positive culture results at LAC+USC. Gram-positive pathogens were found to be the most common at both DEI (70%) and LAC+USC (68%), with coagulase-negative Staphylococcus being the most common gram-positive organism (58% at DEI and 44% at LAC+USC). Pseudomonas aeruginosa was the most common gram-negative organism (57% at DEI and 43% at LAC+USC). Ciprofloxacin and levofloxacin susceptibility for all tested pathogens was 73% at DEI and 81% at LAC+USC (P = 0.16). Oxacillin-resistant Staphylococcus aureus (ORSA) was found in 42% of cases at DEI and in 45% of cases at LAC+USC (P = 1.00).There is no significant difference in the spectrum of pathogens or antibiotic susceptibility of pathogens at DEI versus LAC+USC, and ORSA was found in approximately half of all S. aureus samples.

The chronic shortage of human organs, tissues and cells for transplantation has inspired research on the possibility of using animal donor tissue instead. Transplantation over a species barrier is associated with rejections which are difficult to control. Therefore, it is generally agreed that successful pig to human xenotransplantation requires donor pigs to be genetically modified. Vascular endothelium is the most immediate barrier between the xenogeneic donor organ and host immune and nonimmune defense systems. Thus, these cells are the prime targets for such genetic modifications. Luciferase assays were used to evaluate the activity and specificity of human endothelial-cell specific promoters in porcine aortic-, microvascular- and nonendothelial cells. The promoters for human Flk-1 (fetal liver kinase-1), Flt-1 (fms-like tyrosine kinase), ICAM-2 (intercellular adhesion molecule-2), thrombomodulin and vWf (von Willebrand factor) supported similar levels of luciferase expression in human and porcine aortic endothelial cells, with the Flk-1 promoter being the strongest followed by the thrombomodulin promoter. Relative to the activity of the CMV promoter, the human endothelial cell-specific promoters all showed less activity in porcine kidney microvascular endothelial cells than in liver or brain microvascular endothelial cells. The thrombomodulin and Flk-1 promoters exhibited similar activity in liver and kidney microvascular endothelial cells, whereas the Flk-1 promoter was stronger in aortic and brain microvascular endothelial cells. Human endothelial cell-specific promoters also showed some degree of specificity in pig, because they supported less luciferase activity in porcine nonendothelial cell lines. Based on the in vitro data and previously published in vivo data, the human Flk-1 and thrombomodulin promoters are good candidate promoters for strong endothelial cell-specific gene expression in transgenic pigs.

Hyperostosis frontalis interna (HFI) has been reported in high frequency among post-menopausal elderly women. Although it was widely discussed in the past, this entity is rarely mentioned in the current pathology literature. We report a postmortem case of a 56 yr-old post-menopausal woman with irregular thickening of the internal surface of the frontal bone. Histology revealed an organized trabecular pattern with overall thickening of the cancellous bone. The periosteum and cortical bone were unaffected. The finding was considered to be unrelated to her death. HFI should be recognized as a benign entity and distinguished from other disorders that involve the frontal skull bone, such as Paget's disease, acromegaly, and malignancy. The etiology of HFI is unknown, but current hypotheses implicate hormonal stimulation.