Hospital-acquired pneumonia (HAP) is a common nosocomial infection and is associated with high mortality. Despite advances in the understanding of the causes and prevention of HAP, it continues to be a frequent complication associated with hospital care. Presently, there are no large retrospective cohort studies on HAP in Japan.

Evident detection of artemisinin resistance markers in patient isolates of Plasmodium falciparum from East Africa threatens the efficacy of artemisinin-based combination therapies (ACTs) as first-line treatment of malaria in sub-Saharan Africa. Repositioning previously used antimalarials as complementary addition to ACTs has been suggested as a viable option to mitigating this threat. This study evaluated the potential benefit of chloroquine (CQ) as a complementary partner to dihydroartemisinin/piperaquine (DHA/PQ) in the treatment of malaria in a mice model.

Mycobacterium bovis is one of the species belonging to the Mycobacterium tuberculosis complex; its attenuated form-Bacillus Calmette-Guérin (BCG)-is used as a live vaccine against tuberculosis. Besides its use as a vaccine, BCG is widely used for treating bladder cancer. However, complications related to its use can lead to disseminated infection with M. bovis, known as BCGosis. BCGosis has multiple manifestations, and its culture requires a long time and complex polymerase chain reaction (PCR), posing challenges to its diagnosis. Herein, we report a case of a 74-year-old man with bladder cancer in whom multiple new arterial aneurysms developed during spondylitis treatment following intravesical BCG administration. The patient presented with syncope and left neck swelling. His medical history included transurethral bladder tumor resection and intravesical BCG therapy for bladder cancer. Sixteen months before he visited our institution, he developed spondylitis (L5/S1), an epidural abscess (L5/S1), and an abscess on the right thigh. Biopsy cultures and PCR confirmed M. tuberculosis complex, leading to antituberculosis drug therapy. Upon admission, multiple aneurysms were identified, and drug therapy was continued. However, new multiple aneurysms developed with the rupture of the right femoral aneurysm, leading to surgical interventions and arterial biopsy. The biopsy showed no signs of mycobacterial infection. Other aneurysm etiologies were ruled out and M. bovis was confirmed by PCR in the specimen from the initial intervertebral disc biopsy; thus, a diagnosis of BCGosis was made. This case highlights the importance of a thorough follow-up to detect new complications, even during treatment.

Liver disease remains a significant concern for people living with HIV (PLWH), especially in those with hepatitis B virus (HBV) and hepatitis C virus (HCV) coinfection. This study assessed the prevalence of viral hepatitis coinfections and evaluated the current state of hepatitis management by HIV care providers in Japan.

Staphylococcus aureus bacteremia (SAB), especially when caused by methicillin-resistant S. aureus (MRSA), is of considerable clinical importance. In recent years, the proportion of MRSA among S. aureus has decreased, and a relative increase in the proportion of methicillin-susceptible S. aureus (MSSA) has been observed. It is therefore necessary to consider both MRSA and MSSA when assessing the microbiological and clinical significance of SAB.

Quality control (QC) of carbapenem susceptibility testing for Gram-negative bacteria faces challenges due to limited measuring ranges and the lack of suitable QC strains. This study aimed to select and evaluate QC strains for meropenem antimicrobial susceptibility testing (AST) through a pilot external quality assessment (EQA).

We report two cases of patients with extensively drug-resistant Salmonella Typhi infection who had recently traveled to Pakistan. These cases suggest that obtaining a detailed travel history and considering the epidemiology of drug-resistant S. Typhi in the suspected area of acquisition is crucial for managing patients with typhoid fever.

Invasive group A Streptococcus (iGAS) infections are rare but potentially fatal. Although the number of invasive group A Streptococcus (iGAS) infections decreased during the coronavirus disease (COVID-19) pandemic, it sharply increased worldwide following the pandemic due to the emergence of M1 strains. In Japan, non-fluminant iGAS infections have not been included in the national survey notification system. Therefore, the clinical and microbiological characteristics of iGAS infection are unknown. In this study, we aimed to clarify the clinical and microbiological characteristics of pediatric iGAS infections.

Prolonged installation of a nephrostomy tube causes colonization of various microorganisms within the lumen of the tube, leading to the development of nephrostomy tube-associated pyelonephritis (NTAP). Patients with malignancy, often necessitating long-term installation of a nephrostomy tube, are susceptible to NTAP. However, information regarding the characteristics of NTAP in this population is limited.

Multiple myeloma (MM) is a common hematologic malignancy and immune dysfunction is a hallmark of the disease. It leads to an increased infection risk, which is still a major cause of mortality. The infection spectrum and characteristics have evolved with the introduction of novel agents. An understanding of risk factors that increasing susceptibility to infection is critical in fighting them. This retrospective study aimed to identify risk factors associated with infection and develop nomogram to qualify the risk of infection.

Teicoplanin (TEIC) is typically administered as a loading dose over 36-48 h. Achieving an effective concentration quickly is expected to treat severe infections, such as sepsis and methicillin-resistant Staphylococcus aureus infections. We aimed to identify the TEIC loading dose to be completed within 24 h, targeting the concentration of 15-30 μg/mL and factors affecting the loading dose by utilizing the decision tree (DT) model.

The bacterium Corynebacterium urealyticum produces urease and can cause encrusted pyelitis, a condition characterized by calcifications of the renal pelvis and ureteral wall, which may obstruct the urinary tract. We describe a case of encrusted pyelitis caused by C. urealyticum in a kidney transplant patient presenting with altered consciousness due to hyperammonemia.

Legionella pneumonia is an important cause of community-acquired pneumonia (CAP). The Japanese Respiratory Society (JRS) pneumonia guideline 2024 proposed use of the Legionella Diagnostic Prediction Score for the management of CAP in adults. The committee for the JRS pneumonia guideline is required to verify the validity of the Legionella Diagnostic Prediction Score for the next revision. In addition, it is necessary to determine appropriate cutoff scores by examining all pneumonia cases. In the present study, we validated the usefulness of the Legionella Diagnostic Prediction Score using SARS-CoV-2 Omicron CAP. We analyzed 116 patients with L. pneumophila CAP and 947 patients with SARS-CoV-2 Omicron CAP. Among Omicron cases, the median Legionella Diagnostic Prediction Score was identical among BA.1, BA.2, BA.5, XBB lineage, BA.2.86 and JN.1 subvariants. The median Legionella Diagnostic Prediction Score was significantly higher in the L. pneumophila CAP group than the SARS-CoV-2 Omicron CAP group (4 vs 1, p<0.0001). When targeting all 947 patients with Omicron subvariants, the diagnostic sensitivity and specificity for the presumptive diagnosis of L. pneumophila CAP were 90.5% and 90.8%, respectively, when a total score ≥ 3 points was set as the cutoff level. When the cutoff score was ≥ 4 points, the diagnostic sensitivity and specificity for presumptive diagnosis of L. pneumophila CAP were 76.7% and 99.6%, respectively. Our results demonstrated that the Legionella Diagnostic Prediction Score had good diagnostic ability during the SARS-CoV-2 Omicron variant epidemic period. To set optimal indicators and cutoff values for the Legionella Diagnostic Prediction Score, the policy of the committee for the JRS pneumonia guideline is to continue testing for all pneumonia types.

The vaccination rate for HPV (Human Papillomavirus) has remained significantly low in Japan because of the administrative suspension of active recommendation. This study investigates the awareness and uptake of the HPV vaccine among healthcare students in Japan following the reinstatement of active recommendation for young women in April 2022.

Ruminococcus gnavus is a microbiota-forming, gram-positive coccus reportedly associated with several diseases, such as Crohn's disease. The number of in vitro studies on it is increasing. However, its clinical information is lacking in the literature, with only a few case reports published to date. To elucidate the significance of this organism, we describe its clinical characteristics in this study.

Clostridioides difficile is a major cause of antimicrobial-associated colitis. While antimicrobial stewardship has reduced the incidence of C. difficile infection (CDI), managing CDI is challenging because knowledge about preventing it is limited among healthcare professionals. To address this, we examined associations between antimicrobial use and CDI development.

There are limited information that need to do appropriate treatment including duration of antibiotic treatments, timing of urinary drainage and pathogenesis of bacteria in calculous pyelonephritis. In the present study, we investigated real-world data on clinical features and succeeded treatment strategies in calculous pyelonephritis cases in our hospital, then, aimed to make predictive model estimating duration of intravenous antibiotics treatment.

Aerococcus urinae, a gram-positive, catalase-negative coccus, has emerged as a notable pathogen in clinical microbiology. It is traditionally associated with urinary tract infections in elderly males with underlying urologic conditions. Recently, A. urinae has been implicated in severe invasive infections outside the genitourinary tract including infective endocarditis, vertebral osteomyelitis, peritonitis, lymphadenitis, and discitis. We present the case of 84-year-old male with a history of aortic graft replacement who presented with five days of fever and fatigue. Blood and urine cultures grew gram-positive cocci, identified as A. urinae. Thoracoabdominal contrast-enhanced CT revealed a slightly increased soft tissue shadowing around the prosthetic stent in the ascending aorta, indicating a possible aortic stent-graft infection. Gallium-67 scintigraphy demonstrated inflammation around the prosthetic stent in the ascending aorta consistent with an aortic stent-graft infection. The patient and family opted for conservative treatment and despite a six-week inpatient course of ampicillin, followed by oral amoxicillin, the patient died one week after discharge. This is the first published case of A. urinae causing an aortic stent-graft infection. Clinicians should remain cognizant of the disseminated source of infection in cases of A. urinae bacteremia.

We present a case of spondylodiscitis caused by Aspergillus fumigatus, which we successfully treated with isavuconazole after voriconazole severe intolerance. Aspergillus spondylodiscitis is a severe and relatively rare form of extra-pulmonary invasive aspergillosis. Typically, voriconazole is the first-choice antifungal drug for treating Aspergillus osteomyelitis or spondylodiscitis. However, isavuconazole, a new antifungal medication, has been demonstrated as non-inferior to voriconazole in cases of invasive aspergillosis. It has the added benefits of fewer hepatobiliary, ocular, and cutaneous side effects. It generally does not demand serum level monitoring and poses fewer risks of drug interactions. Nonetheless, there are no studies yet that support its use in spondylodiscitis, and published experiences are very limited and based on isolated cases, albeit mainly positive. The case we present here aims to provide additional evidence on the efficacy and tolerability of isavuconazole in treating this condition.

Non-vaccine serotype (NVT) pneumococcal pneumonia in Japan has increased with the spread of pneumococcal vaccinations. However, there is no data regarding the clinical background and antimicrobial susceptibility of NVT isolates compared with those of vaccine serotype (VT) isolates in adult pneumococcal pneumonia.