In Vitro Susceptibility of Typhoidal, Nontyphoidal, and Extended-Spectrum-ß-Lactamase-Producing Salmonella to Ceftolozane/Tazobactam.

Both typhoidal and nontyphoidal salmonellae are included in the top 15 drug-resistant threats described by the U.S. Centers for Disease Control and Prevention. There is an urgent need to look for alternative antibiotics for the treatment of Salmonella infections. We used the broth microdilution test to examine the in vitro susceptibilities of typhoidal and nontyphoidal salmonellae, including isolates positive for extended-spectrum ß-lactamase (ESBL), to ceftolozane/tazobactam and six other antibiotics. Of the 313 (52 typhoidal and 261 nontyphoidal) Salmonella isolates tested, 98.7% were susceptible to ceftolozane/tazobactam. Based on the overall MIC50/90 values, Salmonella isolates were more susceptible to ceftolozane/tazobactam (0.25/0.5 mg/L) than all the comparator agents: ampicillin (≥64/≥64 mg/L), levofloxacin (0.25/1 mg/L), azithromycin (4/16 mg/L), ceftriaxone (≤0.25/4 mg/L), chloramphenicol (8/≥64 mg/L), and trimethoprim/sulfamethoxazole (1/≥8 mg/L). Comparison of the activities of the antimicrobial agents against nontyphoidal Salmonella isolates according to their serogroups showed that ceftolozane/tazobactam had the highest activity (100%) against Salmonella serogroup D, G, I, and Q isolates, whereas the lowest activity (85.7%) was observed against serogroup E isolates. All 10 ESBL-producing Salmonella isolates (all nontyphoidal), of which 8 were CTX-M-55 producers and 2 were CTX-M-65 producers, were sensitive to ceftolozane/tazobactam, albeit with MIC50/90 values higher (1/2 mg/L) than those for non-ESBL producers (0.25/0.5 mg/L). In summary, our data indicate that ceftolozane/tazobactam is active against most strains of both typhoidal and nontyphoidal salmonellae and also against ESBL-producing salmonellae.

Rare/cryptic Aspergillus species infections and importance of antifungal susceptibility testing.

BACKGROUND: The number of patients infected with Aspergillus rose dramatically in recent years. However, studies on the clinical spectrum and antifungal susceptibilities of non-classical (non-fumigatus, non-flavus, non-niger and non-terreus) pathogenic Aspergillus species are very limited. OBJECTIVES: We examined the clinical spectrum and antifungal susceptibilities of 34 non-duplicated, non-classical Aspergillus isolates collected from Hong Kong, Shenzhen and Shanghai. METHODS: The Aspergillus isolates were identified by internal transcribed spacer, partial BenA and partial CaM sequencing and phylogenetic analyses. Susceptibility testing against eight antifungals was performed following the European Committee for Antimicrobial Susceptibility Testing's methodology. RESULTS: The 34 Aspergillus isolates were identified as 14 different rare/cryptic species of four sections (Flavi [n = 8], Nidulantes [n = 8], Nigri [n = 17] and Restricti [n = 1]). Except for one patient whose clinical history could not be retrieved, 72.7% of the remaining patients had underlying conditions predisposing them to Aspergillus infections. The most common diseases were pulmonary infections (n = 15), followed by skin/nail infections (n = 6), chronic otitis externa and/or media (n = 5), wound infections (n = 2) and mastoiditis/radionecrosis (n = 1), while three were colonisations. Five patients succumbed due to the infections during the admission, and another two died 5 years later because of chronic pulmonary aspergillosis. Antifungal susceptibility testing showed that they possessed different susceptibility profiles compared to the classical Aspergillus species. The majority of isolates characterised were sensitive or wild-type to amphotericin B. The minimum effective concentrations for all the three echinocandins were also low. CONCLUSION: Susceptibility testing should be performed for infections due to these rare/cryptic Aspergillus species to guide proper patient management.

Molecular Identification of Spirometra erinaceieuropaei Tapeworm in Cases of Human Sparganosis, Hong Kong.

Human sparganosis is a foodborne zoonosis endemic in Asia. We report a series of 9 histologically confirmed human sparganosis cases in Hong Kong, China. All parasites were retrospectively identified as Spirometra erinaceieuropaei. Skin and soft tissue swelling was the most common symptom, followed by central nervous system lesions.

In Vitro Activity of Posaconazole against Talaromyces marneffei by Broth Microdilution and Etest Methods and Comparison to Itraconazole, Voriconazole, and Anidulafungin.

We determined the susceptibilities of 57 Talaromyces marneffei strains to anidulafungin, itraconazole, voriconazole, and posaconazole with MICs of 2 to 8, 0.002 to 0.004, 0.016 to 0.063, and 0.001 to 0.002 µg/ml by broth microdilution and >32, ≤0.002 to 0.008, ≤0.002 to 0.008, and ≤0.002 µg/ml by Etest, respectively, at yeast phase; MICs at mycelial phase for anidulafungin and posaconazole were 1 to 2 and 0.004 to 0.063 µg/ml, respectively. The results suggest promising activities of posaconazole. Etest can be used for testing of azoles against T. marneffei.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry for rapid identification of mold and yeast cultures of Penicillium marneffei.

BACKGROUND: Penicillium marneffei is the most important thermal dimorphic fungus causing systemic mycosis in HIV-infected and other immunocompromised patients in Southeast Asia. However, laboratory diagnosis of penicilliosis, which relies on microscopic morphology and mycelial-to-yeast conversion, is time-consuming and expertise-dependent, thus delaying diagnosis and treatment. Although matrix -assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is useful for identification of various medically important fungi, its performance for identification of P. marneffei is less clear. RESULTS: We evaluated the performance of the Bruker MALDI-TOF MS system for identification of mold and yeast cultures of 59 clinical strains and the type strain of P. marneffei using the direct transfer method, with results compared to four phylogenetically closely related species, P. brevi-compactum, P. chrysogenum, Talaromyces aurantiacus and T. stipitatus. Using the Bruker original database combined with BDAL v4.0.0.1 and Filamentous Fungi Library 1.0, MALDI-TOF MS failed to identify the 60 P. marneffei strains grown in mold and yeast phase (identified as P. funiculosum and P. purpurogenum with scores <1.7 respectively). However, when the combined database was expanded with inclusion of spectra from 21 P. marneffei strains in mold and/or yeast phase, all the remaining 39 P. marneffei strains grown in mold or phase were correctly identified to the species level with score >2.0. The MS spectra of P. marneffei exhibited significant difference to those of P. brevi-compactum, P. chrysogenum, T. aurantiacus and T. stipitatus. However, MALDI-TOF MS failed to identify these four fungi to the species level using the combined database with or without spectra from P. marneffei. CONCLUSIONS: MALDI-TOF MS is useful for rapid identification of both yeast and mold cultures of P. marneffei and differentiation from related species. However, accurate identification to the species level requires database expansion using P. marneffei strains.

Gordonia hongkongensis sp. nov., isolated from blood culture and peritoneal dialysis effluent of patients in Hong Kong.

Two bacterial strains, HKU50T and HKU46, were isolated in Hong Kong from the blood culture and the peritoneal dialysis effluent of two patients. The strains are Gram-stain-positive, acid-fast, non-motile, non-sporulating bacilli. They grow on Columbia agar with 5 % defibrinated sheep blood and brain-heart infusion agar under aerobic conditions with 5 % CO2 at 37 °C as pink-to-orange, non-haemolytic colonies. The strains are catalase-positive and oxidase-negative, and have a unique biochemical profile distinguishable from other closely related species. DNA sequencing revealed that both isolates possessed multiple intra-genomic 16S rRNA gene copies (99.8-100 % sequence identities to Gordonia lacunae NRRL B-24551T and Gordonia terrae NRRL B-16283T). Phylogenetic analysis of the 16S rRNA gene, secA1 and gyrB showed that the two isolates formed a distinct branch within the genus Gordonia and were most closely related to G. lacunae and G. terrae. DNA-DNA hybridization demonstrated ≤53.7 % and ≤49.4 % DNA relatedness between the two isolates and G. lacunae, and between the two isolates and G. terrae, respectively. Hierarchical cluster analysis of MALDI-TOF MS main spectrum profiles showed that strains HKU50T and HKU46 were closely related to each other, but were distinct from G. lacunae, G. terrae, or any other species of the genus Gordonia in the Bruker database. The chemotaxonomic traits of the two strains were highly similar, and the major fatty acids were summed feature 4 (iso-C15 : 0 2-OH/C16 : 1trans-9), C16 : 0, C18 : 1cis-9, and tuberculostearic acid. A novel species named Gordonia hongkongensis sp. nov. is proposed to accommodate strains HKU50T and HKU46, with strain HKU50T (=CCOS 955T=CIP 111027T=NBRC 111234T=NCCP 16210T) as the type strain.

High recurrence rate supports need for secondary prophylaxis in non-HIV patients with disseminated mycobacterium avium complex infection: a multi-center observational study.

BACKGROUND: Long-term outcomes in non-HIV immunocompromised patients with disseminated Mycobacterium avium complex (dMAC) infections are unknown and the need for post-treatment secondary prophylaxis against MAC is uncertain in this setting. The objective of this study was to determine the need of continuing secondary anti-MAC prophylaxis in non-HIV patients after completing treatment of the primary dMAC episode. METHODS: We conducted a ten-year multi-center analysis of non-HIV immunosuppressed patients with dMAC infections in Hong Kong. RESULTS: We observed sixteen patients with dMAC during the study period of which five (31 %) were non-HIV immunosuppressed patients. In the non-HIV immunosuppressed group, three patients completed a treatment course without secondary prophylaxis, one patient received azithromycin-based secondary prophylaxis and one patient was still receiving therapy for the first dMAC episode. All the three patients who completed treatment without being given secondary prophylaxis developed recurrent dMAC infection requiring retreatment. CONCLUSIONS: In view of the high rate of dMAC infection recurrence in non-HIV immunocompromised patients following treatment completion, our data support long-term anti-MAC suppression therapy after treatment of the first dMAC infection episode in immunocompromised non-HIV patients, as is recommended for patients with advanced HIV. Tests of cell mediated immune function need to be evaluated to guide prophylaxis discontinuation in non-HIV patients.

Evidence for Elizabethkingia anophelis transmission from mother to infant, Hong Kong.

Elizabethkingia anophelis, recently discovered from mosquito gut, is an emerging bacterium associated with neonatal meningitis and nosocomial outbreaks. However, its transmission route remains unknown. We use rapid genome sequencing to investigate 3 cases of E. anophelis sepsis involving 2 neonates who had meningitis and 1 neonate's mother who had chorioamnionitis. Comparative genomics revealed evidence for perinatal vertical transmission from a mother to her neonate; the 2 isolates from these patients, HKU37 and HKU38, shared essentially identical genome sequences. In contrast, the strain from another neonate (HKU36) was genetically divergent, showing only 78.6% genome sequence identity to HKU37 and HKU38, thus excluding a clonal outbreak. Comparison to genomes from mosquito strains revealed potential metabolic adaptations in E. anophelis under different environments. Maternal infection, not mosquitoes, is most likely the source of neonatal E. anophelis infections. Our findings highlight the power of genome sequencing in gaining rapid insights on transmission and pathogenesis of emerging pathogens.

Gordonia species as emerging causes of continuous-ambulatory-peritoneal-dialysis-related peritonitis identified by 16S rRNA and secA1 gene sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).

We report here four cases of continuous ambulatory peritoneal dialysis-related peritonitis caused by three different species of Gordonia. The portal of entry was likely through Tenckhoff catheters. 16S rRNA and secA1 gene sequencing are so far the most reliable methods for the accurate identification of Gordonia species.

Streptobacillus hongkongensis sp. nov., isolated from patients with quinsy and septic arthritis, and emended descriptions of the genus Streptobacillus and Streptobacillus moniliformis.

Two bacterial strains, HKU33(T) and HKU34, were isolated in Hong Kong from the pus aspirated from the right peritonsillar abscess of a patient with quinsy and the left elbow joint fluid of another patient with tophaceous gout and left elbow septic arthritis, respectively. The bacteria were Gram-stain-negative, non-motile, non-spore-forming, non-haemolytic pleomorphic bacilli. They grew best on Columbia agar with 5 % defibrinated sheep blood in an anaerobic environment or aerobic environment with 5 % CO2. They also grew on chocolate agar but not on MacConkey agar. They were catalase- and cytochrome oxidase-negative. They showed a unique profile of enzyme activities distinguishable from their closely related species. Phylogenetic analysis of the complete 16S rRNA gene, and partial groEL, gyrB and recA gene sequences showed the two isolates formed a distinct branch within the family Leptotrichiaceae, being related most closely to Streptobacillus moniliformis. Hierarchical cluster analysis of mass spectra of whole-cell protein contents showed that strains HKU33(T) and HKU34 were closely related to each other, but were distinct from Streptobacillus moniliformis, Sneathia sanguinegens and 'Leptotrichia amnionii'. The DNA G+C content of strain HKU33(T) was 26.0±2.1 mol% (mean±sd; n = 3). DNA-DNA hybridization demonstrated ≤45.02 % DNA relatedness between the two isolates and Streptobacillus moniliformis CCUG 13453(T). A novel species, Streptobacillus hongkongensis sp. nov., is proposed to accommodate strains HKU33(T) and HKU34, with HKU33(T) ( = JCM 18691(T) = NCTC 13659(T) = DSM 26322(T)) designated the type strain. Emended descriptions of the genus Streptobacillus and Streptobacillus moniliformis are also given.

Mycobacterium abscessus bacteremia after receipt of intravenous infusate of cytokine-induced killer cell therapy for body beautification and health boosting.

BACKGROUND: We report the first series of Mycobacterium abscessus bacteremia after cytokine-induced killer cell therapy for body beautification and health boosting. METHODS: The clinical manifestations, laboratory and radiological investigations, cytokine/chemokine profiles, and outcomes were described and analyzed. RESULTS: Four patients were admitted, and 3 patients had septic shock. Chest radiographs showed pulmonary infiltrates in all patients. Three patients developed peripheral gangrene, and 1 patient required lower limb and finger amputations. Patient 1 also developed disseminated infection including meningitis and urinary tract infection. Postmortem examination of patient 1 showed focal areas of pulmonary hemorrhage and diffuse alveolar damage, splenic infarct, adrenal necrosis, and hemorrhage, and acid-fast bacilli (AFB) were seen in the lung, liver, kidney, and adrenal gland. Patient 2 developed inguinal granulomatous lymphadenitis about 40 days after onset of lower limb gangrene. Wedge-shaped pulmonary infarcts were found in patient 3, and retinitis and subcutaneous lesions developed in patient 4. Patients in septic shock had dysregulated cytokine/chemokine profiles. Patient 4 with relatively milder presentation had increasing levels of interleukin 17 and cytokines in the interferon-γ/interleukin 12 pathway. All survivors required prolonged intravenous antibiotics. Blood cultures grew M. abscessus for all patients, and admission peripheral blood smear revealed AFB for 3 patients. Mycobacterium abscessus was also isolated from respiratory specimens (2 patients), urine (1 patient), and cerebrospinal fluid (1 patient). Time to initial blood culture positivity (patients 1, 2, and 3: ≤52 hours; patient 4: 83 hours) appeared to correlate with disease severity. CONCLUSIONS: Empirical coverage for rapidly growing mycobacteria should be considered in patients with sepsis following cosmetic procedures.

Automated pangenomic analysis in target selection for PCR detection and identification of bacteria by use of ssGeneFinder Webserver and its application to Salmonella enterica serovar Typhi.

With the advent of high-throughput DNA sequencing, more than 4,000 bacterial genomes have been sequenced and are publicly available. We report a user-friendly web platform, ssGeneFinder Webserver (http://147.8.74.24/ssGeneFinder/), which is updated weekly for the automated pangenomic selection of specific targets for direct PCR detection and the identification of clinically important bacteria without the need of gene sequencing. To apply the ssGeneFinder Webserver for identifying specific targets for Salmonella enterica serovar Typhi, we analyzed 11 S. Typhi genomes, generated two specific targets, and validated them using 40 S. Typhi, 110 non-Typhi Salmonella serovars (serovar Paratyphi A, n = 4; Paratyphi B, n = 1; Typhimurium, n = 5; Enteritidis, n = 12; non-Paratyphi group A, n = 6; non-Paratyphi group B, n = 29; non-Paratyphi group C, n = 12; non-Typhi group D, n = 35; group E and others, n = 6), 115 Enterobacteriaceae isolates (Escherichia, n = 78; Shigella, n = 2; Klebsiella, n = 13; Enterobacter, n = 9; others, n = 13), and 66 human stool samples that were culture negative for S. Typhi. Both targets successfully detected all typical and atypical S. Typhi isolates, including an H1-j flagellin gene mutant, an aflagellated mutant which reacted with 2O Salmonella antiserum, and the Vi-negative attenuated vaccine strain Ty21a. No false positive was detected from any of the bacterial isolates and stool samples. DNA sequencing confirmed the identity of all positive amplicons. The PCR assays have detection limits as low as 100 CFU per reaction and were tested using spiked stool samples. Using a pangenomic approach, ssGeneFinder Webserver generated targets specific to S. Typhi. These and other validated targets should be applicable to the identification and direct PCR detection of bacterial pathogens from uncultured, mixed, and environmental samples.

High mortality associated with Catabacter hongkongensis bacteremia.

Catabacter hongkongensis is a recently described catalase-positive, motile, anaerobic, nonsporulating, Gram-positive coccobacillus that was first isolated from blood cultures of four patients from Hong Kong and Canada. Although DNA sequences representing C. hongkongensis have been detected in environmental sources, only one additional case of human infection has been reported, in France. We describe five cases of C. hongkongensis bacteremia in Hong Kong, two presenting with sepsis, one with acute gangrenous perforated appendicitis, one with acute calculous cholecystitis, and one with infected carcinoma of colon. Three patients, with gastrointestinal malignancy, died during admission. All five isolates were catalase positive, motile, and negative for indole production and nitrate reduction and produced acid from arabinose, glucose, mannose, and xylose. They were unambiguously identified as C. hongkongensis by 16S rRNA gene analysis. Of the total of 10 reported cases of C. hongkongensis bacteremia in the literature and this study, most patients had underlying diseases, while two cases occurred in healthy young individuals with acute appendicitis. Six patients presented with infections associated with either the gastrointestinal or biliary tract, supporting the gastrointestinal tract as the source of bacteremia. C. hongkongensis bacteremia is associated with a poor prognosis, with a high mortality of 50% among reported cases, especially in patients with advanced malignancies. All reported isolates were susceptible to metronidazole. Identification of more C. hongkongensis isolates by 16S rRNA gene sequencing will help better define its epidemiology and pathogenesis.

Hong Kong Drug Allergy Delabelling Initiative (HK-DADI) consensus statements for penicillin allergy testing by nonallergists.

Introduction: Penicillin allergy testing has been traditionally performed by allergists, but there remains a huge deficit of specialists. A multidisciplinary effort with nonallergists would be invaluable to overcome the magnitude of penicillin allergy labels via the Hong Kong Drug Allergy Delabelling Initiative (HK-DADI). These consensus statements (CSs) offer recommendations and guidance to enable nonallergists to screen for low-risk (LR) patients and perform penicillin allergy testing. Methods: CSs were formulated by the HK-DADI Group using the Delphi method. An agreement was defined as greater than or equal to 80% consensus. Results: A total of 26 CSs reached consensus after multiple rounds of Delphi. CSs were categorized into risk assessment, skin testing, drug provocation testing (DPT), and post-testing management. For risk assessment, the essentials of allergy history and exclusion criteria were detailed. Patients with only LR features can proceed with testing by nonallergists. Skin tests should be performed prior to DPT. Details regarding the timing, preparation, and interpretation of skin tests were elaborated. DPT remains the gold standard to diagnose genuine allergy or tolerance and should be performed when there is a low pretest probability following negative skin testing. Details of DPT preparations, dosing protocols, and interpretation were elaborated. For post-testing management, inaccurate allergy labels should be delabeled following negative DPT with proper patient counseling. Conclusion: CSs support penicillin allergy testing by nonallergists in Hong Kong. LR cases can be managed by nonallergists at Spoke Clinics, with training and support of an allergist-led Hub.

Three cases of severe invasive infections caused by Campylobacter rectus and first report of fatal C. rectus infection.

We report the first fatal case of Campylobacter rectus infection due to a subdural empyema and ruptured mycotic intracranial aneurysm and two cases of limb-threatening C. rectus necrotizing soft tissue and bone infection and empyema thoracis that responded to amoxicillin-clavulanate and surgical debridement and drainage. All three strains were identified by 16S rRNA sequencing.

Novel pan-genomic analysis approach in target selection for multiplex PCR identification and detection of Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia cepacia complex species: a proof-of-concept study.

Burkholderia pseudomallei, Burkholderia thailandensis, and the Burkholderia cepacia complex differ greatly in pathogenicity and epidemiology. Yet, they are occasionally misidentified by biochemical profiling, and even 16S rRNA gene sequencing may not offer adequate discrimination between certain species groups. Using the 23 B. pseudomallei, four B. thailandensis, and 16 B. cepacia complex genome sequences available, we identified gene targets specific to each of them (a Tat domain protein, a 70-kDa protein, and a 12-kDa protein for B. pseudomallei, B. thailandensis, and the B. cepacia complex, respectively), with an in-house developed algorithm. Using these targets, we designed a robust multiplex PCR assay useful for their identification and detection from soil and simulated sputum samples. For all 43 B. pseudomallei, seven B. thailandensis, and 20 B. cepacia complex (B. multivorans, n = 6; B. cenocepacia, n = 3; B. cepacia, n = 4; B. arboris, n = 2; B. contaminans, B. anthina, and B. pyrrocinia, n = 1 each; other unnamed members, n = 2) isolates, the assay produced specific products of predicted size without false positives or negatives. Of the 60 soil samples screened, 19 (31.6%) and 29 (48.3%) were positive for B. pseudomallei and the B. cepacia complex, respectively, and in four (6.7%) soil samples, the organisms were codetected. DNA sequencing confirmed that all PCR products originated from their targeted loci. This novel pan-genomic analysis approach in target selection is simple, computationally efficient, and potentially applicable to any species that harbors species-specific genes. A multiplex PCR assay for rapid and accurate identification and detection of B. pseudomallei, B. thailandensis, and the B. cepacia complex was developed and verified.

High Prevalence and Mechanism Associated With Extended Spectrum Beta-Lactamase-Positive Phenotype in Laribacter hongkongensis.

In this study, we reported the prevalence and mechanism associated with the extended-spectrum beta-lactamase (ESBL)-positive phenotype in Laribacter hongkongensis isolated from patients and fish. Using the inhibition zone enhancement test, 20 (95.2%) of the 21 patient strains and 8 (57.1%) of the 14 fish strains were tested ESBL-positive. However, ESBL genes, including SHV, TEM, CTX-M, GES, and PER, were not detected in all of these 28 L. hongkongensis isolates. No ESBL gene could be detected in either the complete genome of L. hongkongensis HLHK9 or the draft genome of PW3643. PCR and DNA sequencing revealed that all the 35 L. hongkongensis isolates (showing both ESBL-positive and ESBL-negative phenotypes) were positive for the ampC gene. When the AmpC deletion mutant, HLHK9ΔampC, was subject to the zone enhancement test, the difference of zone size between ceftazidime/clavulanate and ceftazidime was less than 5 mm. When boronic acid was added to the antibiotic disks, none of the 28 "ESBL-positive" isolates showed a ≥ 5 mm enhancement of inhibition zone size diameter between ceftazidime/clavulanate and ceftazidime and between cefotaxime/clavulanate and cefotaxime. A high prevalence (80%) of ESBL-positive phenotype is present in L. hongkongensis. Overall, our results suggested that the ESBL-positive phenotype in L. hongkongensis results from the expression of the intrinsic AmpC beta-lactamase. Confirmatory tests should be performed before issuing laboratory reports for L. hongkongensis isolates that are tested ESBL-positive by disk diffusion clavulanate inhibition test.

Association of HLA-B22 serotype with SARS-CoV-2 susceptibility in Hong Kong Chinese patients.

The coronavirus disease 2019 (COVID-19) is a highly infectious disease caused by SARS-CoV-2. Since its first report in December 2019, COVID-19 has evolved into a global pandemic causing massive healthcare and socioeconomic challenges. HLA system is critical in mediating anti-viral immunity and recent studies have suggested preferential involvement of HLA-B in COVID-19 susceptibility. Here, by investigating the HLA-B genotypes in 190 unrelated Chinese patients with confirmed COVID-19, we identified a significant positive association between the B22 serotype and SARS-CoV-2 infection (p = 0.002, Bonferroni-corrected p = 0.032). Notably, the B22 serotype has been consistently linked to susceptibility to other viral infections. These data not only shed new insights into SARS-CoV-2 pathogenesis and vaccine development but also guide better infection prevention/control.

A Sensitive and Specific Competitive Enzyme-Linked Immunosorbent Assay for Serodiagnosis of COVID-19 in Animals.

In addition to human cases, cases of COVID-19 in captive animals and pets are increasingly reported. This raises the concern for two-way COVID-19 transmission between humans and animals. Here, we developed a SARS-CoV-2 nucleocapsid protein-based competitive enzyme-linked immunosorbent assay (cELISA) for serodiagnosis of COVID-19 which can theoretically be used in virtually all kinds of animals. We used 187 serum samples from patients with/without COVID-19, laboratory animals immunized with inactive SARS-CoV-2 virions, COVID-19-negative animals, and animals seropositive to other betacoronaviruses. A cut-off percent inhibition value of 22.345% was determined and the analytical sensitivity and specificity were found to be 1:64-1:256 and 93.9%, respectively. Evaluation on its diagnostic performance using 155 serum samples from COVID-19-negative animals and COVID-19 human patients showed a diagnostic sensitivity and specificity of 80.8% and 100%, respectively. The cELISA can be incorporated into routine blood testing of farmed/captive animals for COVID-19 surveillance.