Differences among epitopes recognized by neutralizing antibodies induced by SARS-CoV-2 infection or COVID-19 vaccination.

SARS-CoV-2 has gradually acquired amino acid substitutions in its S protein that reduce the potency of neutralizing antibodies, leading to decreased vaccine efficacy. Here, we attempted to obtain mutant viruses by passaging SARS-CoV-2 in the presence of plasma samples from convalescent patients or vaccinees to determine which amino acid substitutions affect the antigenicity of SARS-CoV-2. Several amino acid substitutions in the S2 region, as well as the N-terminal domain (NTD) and receptor-binding domain (RBD), affected the neutralization potency of plasma samples collected from vaccinees, indicating that amino acid substitutions in the S2 region as well as those in the NTD and RBD affect neutralization by vaccine-induced antibodies. Furthermore, the neutralizing potency of vaccinee plasma samples against mutant viruses we obtained or circulating viruses differed among individuals. These findings suggest that genetic backgrounds of vaccinees influence the recognition of neutralizing epitopes.

Successful medical management of Pythium insidiosum keratitis using a combination of minocycline, linezolid, and chloramphenicol.

PURPOSE: To report successful medical management of Pythium insidiosum keratitis using an antibiotic combination of minocycline, linezolid, and chloramphenicol. OBSERVATIONS: A 20-year-old Japanese man was referred for visual disturbance, hyperemia, and discharge from his right eye. Slit-lamp examination revealed a paracentral corneal hyphate ulcer. His visual acuity was 20/28. Smear examination of corneal scrapings revealed a filamentous fungus. Pimaricin ointment four times a day and voriconazole eye drops hourly were initially prescribed. Although intravenous liposomal amphotericin B 100 mg was added, the corneal infiltrates and ulcer worsened. The possibility of P. insidiosum keratitis was considered, and in vitro antifungal susceptibility testing were performed based on the disc diffusion method. The inhibition zones around each antibiotic disc revealed that the pathogen was susceptible to minocycline, linezolid, and chloramphenicol. Therefore, minocycline ointment four times a day, chloramphenicol eye drops hourly, and linezolid 1200 mg orally per day were also administered. Eventually, sequencing of ribosomal DNA confirmed the pathogen to be P. insidiosum. The triple regimen dramatically improved the patient's keratitis. Therapeutic penetrating keratoplasty for corneal perforation was successfully performed, and his visual acuity recovered from 20/2000 to 20/25. CONCLUSIONS AND IMPORTANCE: We have encountered a case of P. insidiosum keratitis that responded to a combination of minocycline, linezolid, and chloramphenicol. This triple combination should be considered in patients with P. insidiosum keratitis.

The Molecular Identification and Antifungal Susceptibilities of Aspergillus Species Causing Otomycosis in Tochigi, Japan.

Aspergillus species are the most common pathogenic fungi involved in otomycosis, an infection of the outer ear canal. In this study, we examined the incidence of Aspergillus infections and the antifungal susceptibilities of 30 Aspergillus species isolates from patients with otomycosis who visited Saiseikai Utsunomiya Hospital between August 2013 and July 2016. Based on the morphological test results, the strains were identified as Aspergillus niger sensu lato (20 strains), A. terreus sensu lato (7 strains), and A. fumigatus sensu lato (3 strains). In contrast, the molecular identifications based on analyzing the isolates' partial ß-tubulin gene sequences revealed them to be A. niger sensu stricto (12 strains), A. tubingensis (8 strains), A. terreus sensu stricto (7 strains), and A. fumigatus sensu stricto (3 strains). The antifungal susceptibility test results indicated that strains of A. tubingensis and A. niger sensu stricto displayed lower susceptibilities to ravuconazole, compared with the other isolates. The Aspergillus strains from this study showed low minimum inhibitory concentrations toward the azole-based drugs efinaconazole, lanoconazole, and luliconazole. Therefore, these topical therapeutic agents may be effective for the treatment of otomycosis.

Mycobacterium mageritense Parotitis in an Immunocompetent Adult.

Mycobacterium mageritense, a rapidly growing mycobacterium, is a rare clinical pathogen. Furthermore, parotitis due to non-tuberculosis mycobacterium is very rare in adults. Herein, we report the first case of M. mageritense parotitis in an immunocompetent adult. A 40-year-old man presented with swelling in a left parotid lesion. He was diagnosed with parotitis. The culture from the parotid abscess grew M. mageritense. He was unsuccessfully treated with levofloxacin monotherapy. Trimethoprim-sulfamethoxazole was added, leading to some clinical response; however, the erythema persisted despite 14 months of antibiotic therapy. Subsequently, the skin lesion was surgically removed. The antibiotic treatment was ceased a week after surgery as the postoperative course was uneventful and the lesion had improved. No recurrence was noted at 7 months after surgery. Although extremely rare, M. mageritense can cause parotitis in immunocompetent adults, and may not be sufficiently treated with antibiotics alone.

Endogenous Fusarium Endophthalmitis During Treatment for Acute Myeloid Leukemia, Successfully Treated with 25-Gauge Vitrectomy and Antifungal Medications.

Endogenous fungal endophthalmitis (EFE) caused by disseminated fusariosis is a rare condition that generally has a poor outcome, even with intensive therapy. Here, we describe a case in which this type of EFE was diagnosed with vitreous sampling and was successfully treated with 25-gauge vitrectomy and antifungals, including liposomal amphotericin B and voriconazole. A 16-year-old male patient undergoing treatment for acute myeloid leukemia complained of eye pain and blurred vision in his right eye. Treatment was initiated for a vitreous opacity, possibly associated with herpetic retinitis, but the patient worsened and he was referred to us. Right-eye visual acuity was limited to light perception. We suspected endogenous endophthalmitis and performed 25-gauge vitrectomy with antibiotic perfusion of ceftazidime, vancomycin, and voriconazole. Vitreous culturing revealed the presence of Fusarium solani species complex, and enhanced computed tomography revealed disseminated fusariosis lesions in the lung, spleen, and the soft tissue of the left upper arm. The patient received antifungal treatment with liposomal amphotericin B and voriconazole, and these conditions were eliminated. Visual acuity recovered to 20/400 after additional vitrectomy for tractional retinal detachment and was maintained at this level during the 6-month follow-up period. The success of our treatment allowed the capture of optical coherence tomography images of the retina during fusarium-associated endogenous endophthalmitis and the follow-up period. Furthermore, this case showed that immediate vitrectomy for suspected EFE and intensive treatment can lead to a good clinical outcome.

Epidural abscess caused by Schizophyllum commune: A rare case of rhinogenic cranial complication by a filamentous basidiomycete.

Central nervous system (CNS) infections due to filamentous basidiomycetes are extremely rare. We encountered a case of epidural abscess due to Schizophyllum commune that extended from sinusitis. A 53-year-old Japanese man presented at our hospital with a headache. Computed tomography (CT) of the cranium and sinuses showed ethmoid and sphenoid sinusitis with no intracranial abnormalities. The patient was diagnosed with acute sinusitis and underwent antibiotic treatment. However, the symptoms deteriorated, and the patient came to our hospital again with consciousness disturbance. CT scan of the cranium and sinuses showed no improvement of sinusitis after antibiotic therapy and an epidural abscess emerged in the middle cranial fossa. Therefore, emergency craniotomy and endoscopic sinus fenestration were performed. Filamentous fungal elements were observed in both rhinorrhoea and epidural abscess. The symptoms improved after the operation and administration of liposomal amphotericin B. The clinical isolate was identified as S. commune by a molecular-based method. To our knowledge, this is the first report of epidural abscess due to this fungus. Although rare, clinicians should be aware that S. commune could be a causative agent of CNS infections.

Desulfovibrio desulfuricans bacteremia in a patient hospitalized with acute cerebral infarction: case report and review.

Desulfovibrio spp. can be found in soil, water, and sewage, as well as in the digestive tracts of animals and humans. We report a case of Desulfovibrio desulfuricans bacteremia during hospitalization with acute cerebral infarction following aspiration bronchopneumonia and severe diarrhea, and the case strongly suggests that Desulfovibrio spp. bacteremia can occur as an infection due to disturbance of endogenous gut flora including antibiotic administration. Because Desulfovibrio spp. is difficult to detect in short-time incubation, its bacteremia is possibly overlooked in hospitalized patients. A few clinical cases of D. desulfuricans bacteremia have been reported in Japan, and they are reviewed briefly in this article.