High genetic heterogeneity of Mycobacterium intracellulare isolated from respiratory specimens

Background M. intracellulare is a frequent causative pathogen of nontuberculous mycobacteria infection that causes infections in the respiratory tract, whose incidence is increasing in many countries. This study aimed at determining the VNTR-based genetic diversity of a collection of 39 M. intracellulare human strains isolated from respiratory specimens over the last 5 years. Results The VNTR analysis showed that M. intracellulare strains displayed a high genetic diversity, indicating that the M. intracellulare genotypes are quite heterogeneous in our geographical area. Moreover, a comparison with VNTR profiles of strains from other countries confirmed that genotypes of clinical strains of M. intracellulare are not related to geographical origin. Conclusions VNTR typing has proved to be a highly discriminatory method for better understanding the molecular epidemiology of M. intracellulare.

Determination of probability of causative pathogen in infectious keratitis using deep learning algorithm of slit-lamp images

Corneal opacities are important causes of blindness, and their major etiology is infectious keratitis. Slit-lamp examinations are commonly used to determine the causative pathogen; however, their diagnostic accuracy is low even for experienced ophthalmologists. To characterize the “face” of an infected cornea, we have adapted a deep learning architecture used for facial recognition and applied it to determine a probability score for a specific pathogen causing keratitis. To record the diverse features and mitigate the uncertainty, batches of probability scores of 4 serial images taken from many angles or fluorescence staining were learned for score and decision level fusion using a gradient boosting decision tree. A total of 4306 slit-lamp images including 312 images obtained by internet publications on keratitis by bacteria, fungi, acanthamoeba, and herpes simplex virus (HSV) were studied. The created algorithm had a high overall accuracy of diagnosis, e.g., the accuracy/area under the curve for acanthamoeba was 97.9%/0.995, bacteria was 90.7%/0.963, fungi was 95.0%/0.975, and HSV was 92.3%/0.946, by group K-fold validation, and it was robust to even the low resolution web images. We suggest that our hybrid deep learning-based algorithm be used as a simple and accurate method for computer-assisted diagnosis of infectious keratitis.

Immune Evasive Effects of SARS-CoV-2 Variants to COVID-19 Emergency Used Vaccines

Coronavirus disease 2019 (COVID-19) pandemic is a serious threat to global public health and social and economic development. Various vaccine platforms have been developed rapidly and unprecedentedly, and at least 16 vaccines receive emergency use authorization (EUA). However, the causative pathogen severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has continued to evolve and mutate, emerging lots of viral variants. Several variants have successfully become the predominant strains and spread all over the world because of their ability to evade the pre-existing immunity obtained after previous infections with prototype strain or immunizations. Here, we summarized the prevalence and biological structure of these variants and the efficacy of currently used vaccines against the SARS-CoV-2 variants to provide guidance on how to design vaccines more rationally against the variants.

Late-onset Endophthalmitis Caused by Streptococcus Cristatus after Trabeculectomy

Purpose: To report a case of late-onset bleb-associated endophthalmitis caused by streptococcus cristatus (S. cristatus) after trabeculectomy.Case summary: A 59-year-old woman presented with left ocular pain and visual disturbance. She had undergone trabeculectomy of the left eye 2 years ago. At the initial visit, she was only able to count fingers from the left eye. Whitish thin bleb, conjunctival injection, and inflammation were observed in the left anterior chamber, and the fundus could not be visualized. Despite administering topical and systemic antibiotics, the chamber reaction worsened, and hypopyon and inflammatory membrane were noticed the next day. Vitrectomy with phacoemulsification and intravitreal antibiotic injection was performed, and the intravitreal antibiotic injections were repeated over the next two days. Bacterial culture of vitreous fluid showed a growth of S. cristatus 5 days after the surgery, and inflammation improved after 7 days. One month later, she was still only able to count fingers from the left eye, but there were no signs of endophthalmitis.Conclusions: Postoperative endophthalmitis after glaucoma filtering surgeries caused by S. cristatus has not been reported previously from Korea. To the best of our knowledge, this is the first Korean case of late-onset bleb-associated endophthalmitis caused by S. cristatus. If gram-positive cocci are grown in samples from the patients with endophthalmitis after trabeculectomy, resident oral microflora such as S. cristatus should be considered as the causative pathogen.

COVID-19 Anosmia: High Prevalence, Plural Neuropathogenic Mechanisms, and Scarce Neurotropism of SARS-CoV-2?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative pathogen of coronavirus disease 2019 (COVID-19). It is known as a respiratory virus, but SARS-CoV-2 appears equally, or even more, infectious for the olfactory epithelium (OE) than for the respiratory epithelium in the nasal cavity. In light of the small area of the OE relative to the respiratory epithelium, the high prevalence of olfactory dysfunctions (ODs) in COVID-19 has been bewildering and has attracted much attention. This review aims to first examine the cytological and molecular biological characteristics of the OE, especially the microvillous apical surfaces of sustentacular cells and the abundant SARS-CoV-2 receptor molecules thereof, that may underlie the high susceptibility of this neuroepithelium to SARS-CoV-2 infection and damages. The possibility of SARS-CoV-2 neurotropism, or the lack of it, is then analyzed with regard to the expression of the receptor (angiotensin-converting enzyme 2) or priming protease (transmembrane serine protease 2), and cellular targets of infection. Neuropathology of COVID-19 in the OE, olfactory bulb, and other related neural structures are also reviewed. Toward the end, we present our perspectives regarding possible mechanisms of SARS-CoV-2 neuropathogenesis and ODs, in the absence of substantial viral infection of neurons. Plausible causes for persistent ODs in some COVID-19 convalescents are also examined.

Outbreak of postoperative endophthalmitis caused by Pseudomonas aeruginosa: a case report and brief literature review

Endophthalmitis is the most serious complication of cataract surgery. A cluster of endophthalmitis is a devastating event for surgeons. Pseudomonas aeruginosa is the main causative pathogen of Gram-negative endophthalmitis, which can be suggestive of the occurrence of an outbreak. Ten patients diagnosed with endophthalmitis after cataract surgery performed by one surgeon were analyzed in this study. At presentation, five patients had obvious clinical findings of endophthalmitis with visual acuity of light perception, two patients had poor light perception/no light perception of vision complicated by concomitant keratitis, and three patients had earlier signs of infection (e.g., a lower degree of anterior chamber and vitreous cells, better presenting visual acuity, and greater visibility of the fundus). Investigations revealed that the source of infection was growth of P. aeruginosa on the phaco probe. All of the surgeries had been performed by the same contaminated probe without sterilization between surgeries. This finding emphasizes the importance of strict adherence to sterility protocols during high-risk surgeries such as intraocular surgeries. Additionally, this report aims to emphasize to surgeons that negligence of simple but vital steps of sterility for any reason, such as limitations in time or equipment, can lead to catastrophic events.

247. The Predictive Value of Methicillin-Resistant Staphylococcus aureus Surveillance Swabs in Septic Arthritis

Background Septic arthritis is a destructive form of acute arthritis secondary to infection. With an annual incidence of 2 to 5 cases per 100 000 individuals, it is associated with significant morbidity and mortality. Prompt source control and antimicrobial therapy remain the mainstays of management. Epidemiology, microbiology studies, and local resistance patterns are important in guiding therapeutic decisions. Staphylococcal and streptococcal species are the most common pathogens with Methicillin-resistant Staphylococcus aureus (MRSA) becoming an increasingly important pathogen. The increasing incidence of MRSA provides clinicians with the challenge of deciding which patients require empiric coverage for MRSA. MRSA nasal screening has been shown to have a high negative predictive value in pneumonia, bloodstream infections, and nosocomial infections in critically ill patients. However, little is known about the diagnostic utility of MRSA surveillance swabs for predicting MRSA infections in septic arthritis. Methods A retrospective cohort study was performed in 3 tertiary hospitals from September 1, 2010 to December 31, 2020. All adult patients with confirmed septic arthritis of the ankle, wrist, knee, or hip and an MRSA surveillance swab performed within 72 hours of admission were included in the study. These data were used to calculate the sensitivity, specificity, positive predictive value and negative predictive value for MRSA surveillance swabs. Results One hundred seventy-two patients met inclusion criteria. Thirty patients had positive MRSA surveillance swabs. The prevalence of MRSA in joint cultures was 11.04%. The positive predictive value of MRSA surveillance swabs was 42.3% and the negative predictive value was 93.5% in all participants. The MRSA surveillance swab had a negative predictive value of 100% in participants with no risk factors for MRSA colonization. Conclusion The negative predictive value of MRSA surveillance swabs used independently is insufficient to confidently rule out MRSA as the causative pathogen in septic arthritis. When used in combination with MRSA risk factors, the absence of MRSA risk factors may help clinicians rule out MRSA as a causative pathogen. Disclosures All Authors: No reported disclosures

Corynebacterium freneyi as a cause of early prosthetic valve endocarditis

Infective endocarditis (IE) is associated with severe complications and a high mortality rate. Identification of the causative pathogen is crucial to optimise treatment. We present a case of prosthetic valve endocarditis caused by Corynebacterium freneyi, a very rare cause of human infection and not previously reported as a cause of IE. Despite proper antibiotic therapy, the patient eventually needed surgery after progression of the infection. After surgery, he quickly recovered without evidence of relapse during an 8-month follow-up period. This report highlights critical decision making in a complex and potentially life-threatening situation, where neither guidelines nor previous clinical or microbiological experience were able to give clear treatment recommendations.

Diagnostic Tests and Procedures During the COVID-19 Pandemic

Coronavirus disease 2019 (COVID-19) has brought a huge impact on global health and the economy. Early and accurate diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections is essential for clinical intervention and pandemic control. This book chapter addresses the evolving approach to the laboratory diagnosis of COVID-19 covering preanalytical, analytical, and postanalytical steps. The rapidly changing dynamics of the COVID-19 pandemic serve as an example which will be important for laboratories to plan for future pandemics. With the quick identification of the causative pathogen and availability of the genome sequence, it will be possible to develop and implement diagnostic tests within weeks of an outbreak. Laboratories will need to be flexible to continuously adapt to changing testing needs and burdens on the healthcare system, plan mitigation strategies for bottlenecks in testing and workflow due to limitations on resources and supplies, and prepare back-up plans now in order to be better prepared for future pandemics.