The importance of “Proper use of antimicrobial agents” is being widely recognized in recent times, and various activities and measures have been implemented at various levels, including at the national and regional levels, across medical institutions, and the relevant academic societies. The Japanese Society of Infectious Diseases Committee on the Appropriate Use of Antimicrobial Agents for Airway Infections published “Recommendations for the Appropriate Use of Antimicrobial Agents for Airway Infections” in 2020. However, considering the effects of coronavirus disease (COVID-19), a revised “Recommendations for the Appropriate Use of Antimicrobial Agents for Airway Infections” was published in 2022.

In addition to outlining the recent changes in antimicrobial use associated with the COVID-19 pandemic, we discuss the concept of “Additional support for appropriate use of antimicrobial agents in pediatric otorhinolaryngology,” which is covered by insurance since 2022. “Additional support for appropriate use of antimicrobial agents in children” is available since 2018, and the same type of additional support is established for the otorhinolaryngology specialty since 2022. To be eligible for the addition, physicians are required to participate in “regional infectious disease control network” activities or regularly attend training sessions on infectious diseases and “provide guidance necessary for medical treatment and provide written explanations.”

It is widely accepted that vaccines and anti-viral drugs are the primary choice for treatment of viral infection. However, the infrastructure challenges and lengthy development periods have always been an barrier to utilize. This paper focuses on human viral infection defense mechanisms and discusses the world-first discovery and effects of lactic acid bacteria that activate plasmacytoid dendritic cells (pDC). In the human immune system, pDCs play a crucial role in sensing external viral invasion and initiating an early response through IFN production, as well as inducing acquired immunity through viral antigen presentation in a later response. We explored pDC-activating lactic acid bacteria, in which contain prominent stimuli of innate immunity from public microbial banks.

Lactococcus lactis strain Plasma was selected as the positive strain based on its ability to induce type I IFN production, a marker of pDC activation. Subsequently animal studies have shown that small amount of oral intakes are highly effective against various viral infections of parainfluenza, rotavirus, and dengue. In clinical trials on healthy subjects, it was effective in reducing influenza-like symptoms in winter and in treating dengue fever and general infectious diseases. Recently, basic and clinical trials of COVID-19 are underway, and results are urgently needed.

Additionally, administering L. lactis strain Plasma to mice has shown anti-aging effects by continuously activating their immune functions.

Palatine and pharyngeal tonsils, along with the nasal mucosa, constitute a series of mucosal tissues that play various roles within the human respiratory tract, including the recognition and uptake of foreign antigens, removal of foreign substances, and prevention of pathogen invasion. Non-specific and specific defense mechanisms in mucosal tissues are regulated through a multi-step process, adapting their immune responses according to the intensity of the stimuli. However, the understanding of the detailed mechanisms including characterization of constituent cells, remains limited. The pathogenesis of various diseases, including allergic rhinitis, chronic sinusitis with polyps (type 2 inflammatory disease), chronic tonsillitis, and tonsillar focal infection results from failure of immune responsiveness in the upper respiratory mucosal tissues. In this review, we provide new insights into the relationship between conformational dynamics and the functional roles of tonsils and epithelial cells in response to a wide variety of stimuli.

Age-related deterioration of T cell function has been reported in various studies. In this study, we investigated changes in mucosal immunity in the upper airway and the kinetics of helper T cells after administering an anti-programmed death-ligand 1 (PD-L1) antibody to mice of different ages. We used mice at four different age groups (6 weeks, 6 months, 12 months, and 18 months) in this study. They were intranasally administered with 10 μg of OMP along with 1 μg of cholera toxin as a mucosal adjuvant three times a week. Intranasal administration was combined with anti-PD-L1 antibody administration in aged mice (12- and 18-month-old mice) to activate mucosal immunity. On day 7 after intranasal immunization, we collected nasal lavage fluid and serum to measure OMP-specific antibody titers. We also collected nasal mucosa, nasal mucosa-associated lymphoid tissue (NALT), cervical lymph nodes, and spleens. From these samples, we isolated mononuclear cells (MNCs) and stained them with various fluorescently labeled antibodies, including anti-CD3a, anti-CD4, anti-CD8, anti-CD69, anti-CD279 (PD-1), and anti-CD185 (CXCR5), for flow cytometric analysis. Although OMP-specific antibody titers decreased with age, they increased in 12-month-old mice with anti-PD-L1 antibody administration. However, 18-month-old mice did not show an increase in OMP-specific antibody titers. Both 12- and 18-month-old mice displayed an increase in the ratio of PD-1-positive CD4-positive T cells after anti-PD-L1 antibody administration. However, only the 12-month-old mice exhibited enhanced CD69 expression in CD4-positive T lymphocytes, indicating lymphocyte activation. Additionally, follicular helper T cells showed an increasing trend in lymphoid tissues in 12-month-old mice but not in 18-month-old mice. The effect of mucosal immune stimulation with anti-PD-L1 antibodies may differ depending on the age of the mouse.

Peritonsillar abscess, with symptoms that may be minor but become more intense within a few days to a week, requires therapeutic intervention by otolaryngologists. We hypothesized that patients with peritonsillar abscesses may not have received appropriate treatment because they refrained from seeking medical attention following the COVID-19 epidemic. In this study, we compared the visits and severity of patients with peritonsillar abscess before and during the COVID-19 epidemic at our hospital. The study analyzed 70 cases of peritonsillar abscesses, which included 29 and 41 cases before and during the epidemic, respectively, treated in our hospital between March 2018 and February 2022. Compared with the cases before the epidemic, the average time from symptom onset to medical attention was 1.9 days longer for patients aged <60 years during the epidemic. C-reactive protein, which was examined as an indicator of severe disease, tended to be worse in patients aged ≥60 years during the epidemic than in those before the epidemic, with mean values of 8.35 and 12.11 mg/dL in patients aged ≥60 years before and during the epidemic, respectively. Moreover, the number of patients who presented with laryngeal edema at the first visit was greater in the group aged ≥60 years during the epidemic. Patients who had seen a doctor before the abscess formation were more common in the group aged >60 years. However, none of the patients in this study had severe diseases, such as airway narrowing or cervical abscess requiring tracheotomy, and we do not think that the delay in seeking medical attention had a significant effect on treatment.

Recently, the prevalence of Japanese cedar pollinosis has been increasing, and it is a national disease in Japan. Yamanashi Prefecture has the highest cedar- and cypress-specific IgE antibody positivity rate and the highest cedar pollinosis prevalence in Japan. A major cause of the increase in prevalence is the increase in pollen antigens. In 1998, we started observation using Durham-type pollen collectors in several areas in Yamanashi Prefecture. Using pollen count data for 25 years up to 2023, we compared regional differences and annual changes and examined their correlation with weather conditions. Regional differences in pollen quantity reflected distance from the pollen source. Cedar pollen increased gradually. Cypress pollen showed differences in the increase rate depending on the region. Both correlated with sunshine duration and average temperature in the previous summer. However, no significant correlation was observed with weather conditions during dispersal. Cypress pollen quantity may increase in all areas in the future.

Somatic cough syndrome (psychogenic cough) is a known cause of persistent cough, particularly in children. We report three cases of pediatric somatic cough syndrome attributed to COVID-19—related events.

Case 1: A 14-year-old adolescent male presented with persistent dry cough for 4 months after COVID-19. He was unable to attend school owing to the cough; however, he denied nighttime cough. Although he coughed throughout the consultation, he had no cough during laryngoscopic examination. We diagnosed the patient with somatic cough syndrome following exclusion of other physical abnormalities and based on the characteristic nature of the cough.

Cases 2 and 3: An 11-year-old adolescent female and 13-year-old adolescent male, respectively had persistent dry cough for more than 40 days after they received the COVID-19 vaccine. The patients had no physical abnormalities, except for mild asthma in the adolescent male. The adolescent female and male had a dry and honking cough, respectively; however, both patients denied nighttime cough. Although we observed cough in both patients in the consultation room, they did not cough during laryngoscopic examination. Based on these features, we diagnosed both patients with somatic cough syndrome.

The COVID-19 pandemic has significantly affected social life and also children’s physical and mental health. Somatic cough syndrome in the aforementioned cases may be attributable to conditioning of coughing associated with COVID-19, fear of long-COVID, or anxiety regarding the adverse effects of COVID-19 vaccines. Our patients’ cough improved 2–6 months after diagnosis. A multidimensional approach is important to treat children with suspected somatic cough syndrome, considering the psychological effects of COVID-19.

Lemierre’s syndrome is characterized by oropharyngeal infection, thrombophlebitis of the internal jugular vein, systemic organ thromboembolism, and a high mortality rate. The most involved distant sites are the lungs, joints, bones, skin, and soft tissue. Central nervous system (CNS) complications occur in 3% of cases. A 62-year-old male was rushed to our emergency department due to chills and immobility. Contrast-enhanced computed tomography showed a right parapharyngeal space abscess, which was drained. Thereafter, antibiotic therapy was started. Blood and abscess cultures on admission revealed Streptococcus constellatus. After admission, hemichorea and psychiatric symptoms appeared. Cerebrospinal fluid examination and contrast-enhanced magnetic resonance imaging revealed meningitis, encephalitis, subdural abscess, and sigmoid sinus thrombosis. In addition to antibiotic therapy, anticoagulation therapy was started, and thrombosis was resolved. Hemichorea and psychiatric symptoms were thought to be caused by inflammatory spillover to the subthalamic nucleus. Although hemichorea improved, psychiatric symptoms persisted. When treating Lemierre’s syndrome, physicians should be aware of the possibility of CNS complications.

Anaphylaxis is a serious systemic hypersensitivity reaction encountered across various domains of clinical practice. We report a case of anaphylaxis after general anesthesia administered for surgery.

A 9-year-old boy with a history of food allergies to kiwi, almonds, and peanuts but without any drug allergy was diagnosed with otitis media with effusion. He underwent ventilation tube insertion under general anesthesia; non-latex gloves were used during the procedure. Following induction using sevoflurane, fentanyl, and rocuronium, endotracheal intubation was performed, and sevoflurane and remifentanil were used to maintain anesthesia. Acetaminophen was administered 20 min before completion of the surgery. Fentanyl was administered after completion of the procedure, and the patient received sugammadex 13 min postoperatively. He developed a mild, dry cough 3 min after extubation; however, his vital signs were stable, and the patient was transferred to the ward. However, the dry cough persisted, and he developed mild wheezing and a pruritic rash on his body, which led to diagnosis of anaphylaxis (Grade 2 severity). The rash rapidly disappeared following administration of adrenaline and other drugs, and the patient was discharged the following morning.

Blood tests performed after discharge confirmed diagnosis of latex allergy, and a basophil activation test confirmed the diagnosis of sugammadex allergy. Although the patient underwent surgery only after following precautions with regard to his known food and latex allergies, anticipation of sugammadex-induced anaphylaxis is difficult. Removal of all allergens preoperatively and diagnosis of possible triggering agents based on methods tailored to the patient are important.