Contamination rate of rare bacterial species detected by MALDI-TOFMS: a retrospective cohort study.

When rare bacterial species are identified in blood cultures, determining the clinical significance is sometimes difficult. This study aimed to analyze the clinical significance of rare bacterial species detected in blood cultures using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS) by comparing their contamination rates with those of common species. We retrospectively analyzed medical records of adult patients with positive blood cultures at Kyoto City Hospital from 2014 to 2022. Rare species were defined by low detection rates and few PubMed reports. Of 4880 microorganisms identified from 3441 individuals, 1150 (23.6%) were classified as contamination. Meanwhile, 24 rare microorganisms were identified, of which 14 (58.3%) were classified as contamination, which was significantly higher than common species (odds ratio 4.56, 95% confidence Interval 1.88-11.50, P < 0.001). These findings may help in determining the clinical significance of rare bacterial species in blood cultures with few reported cases.

A case of amebic colitis and liver abscesses that occurred after treatment of coronavirus disease 2019 with dexamethasone.

Entamoeba histolytica infections, which can be asymptomatic, are endemic to developing countries; traveling to such countries is a risk factor for contracting these infections. A 65-year-old Japanese man was hospitalized for coronavirus disease 2019 (COVID-19)-associated respiratory distress, and was treated with remdesivir, dexamethasone, and oxygen supplementation. Although his respiratory condition improved and the oxygen support was discontinued, he developed a fever, severe abdominal pain, and diarrhea on day 13 of hospitalization. Fifteen years ago, he was hospitalized for diarrhea of an unknown origin in Suzhou, China, and had a history of passing loose stools for 1 year. Contrast-enhanced abdominal and pelvic computed tomography revealed liver abscesses in both lobes and intestinal edema from the ascending colon to the descending colon. The abscesses were suspected to be amebic based on the characteristics of the drained abscess fluid. The patient was treated with cefotaxime and metronidazole, and his temperature declined and abdominal pain improved. A culture analysis of abscess fluid yielded negative findings; however, polymerase chain reaction analyses of abscess and stool samples were positive for Entamoeba histolytica. We speculated that the patient was infected with Entamoeba histolytica while in China, and that the corticosteroid usage for COVID-19 had exacerbated the infection. Clinicians should be aware that corticosteroid treatments can lead to recurrent invasive amebiasis in asymptomatic amebic carriers.

Two cases of pyelonephritis with bacteremia by Staphylococcus epidermidis in male patients with nephrolithiasis: Case reports and a literature review.

BACKGROUND: Staphylococcus epidermidis is a common cause of health care-associated bacteremia, especially in patients with an indwelling medical device. However, S. epidermidis is an uncommon causative organism in catheter-associated urinary tract infection, and rare pyelonephritis without any indwelling urinary device. To our knowledge, there are few cases reported of bacteremia secondary to urinary tract infection. We report two cases of pyelonephritis with bacteremia by S. epidermidis in male patients with unilateral nephrolithiasis and review prior case reports. CASE PRESENTATION: Case 1: 74-year-old man with a history of diabetes and overactive bladder had fever and pyuria with a right nephrolithiasis on abdominal CT scan. Case 2: 79-year-old man with a history of diabetes and post-myocardial infarction status had fever with a left nephrolithiasis on abdominal CT scan. In both cases, both the urine culture collected at ureteral stenting and blood culture were positive for S. epidermidis. We initiated intravenous antibiotics in these patients in addition to ureteral stenting. CONCLUSIONS: S. epidermidis is acknowledged as an uncommon pathogen that can cause bacteremia secondary to pyelonephritis without an indwelling urinary device. Clinicians should consider the possibility of pyelonephritis due to S. epidermidis if the pathogen is identified in blood and urine in patients with nephrolithiasis.

Two Cases of Kikuchi Disease Presenting with Aseptic Meningitis and Encephalitis.

Kikuchi disease, also called histiocytic necrotizing lymphadenitis, is an idiopathic and generally self-limiting disease affecting young adults and children. Kikuchi disease does not commonly manifest neurological complications at its initial presentation. We herein report two cases of Kikuchi disease that initially presented with aseptic meningitis and encephalitis rather than the more common signs of lymphadenopathy, rash, and arthritis. A 15-year-old boy presented with aseptic meningitis with an extremely high intracranial pressure. A 28-year-old man presented with dysesthesia of the right lower extremity, coinciding with abnormal magnetic resonance imaging findings. In both cases, painful cervical lymphadenopathy was observed following the central nervous system symptoms. Both patients improved after treatment with steroids. Kikuchi disease occasionally affects the central nervous system, to which lymphadenitis may be observed subsequently. A repeated, careful physical examination of the cervical lymph nodes may be helpful for the diagnosis.

Cervical abscess caused by Mycobacterium tilburgii in a patient carrying anti-interferon gamma autoantibody: A case report and literature review.

Mycobacterium tilburgii, a nonculturable mycobacterium, is an important nontuberculous mycobacterium that occasionally causes serious infections in patients with cellular immune deficiencies. Due to its nonculturable nature, information about its drug susceptibility is not available, and data about its clinical response to antimycobacterial treatment remains insufficient. Here, we report a case of a patient who presented with neck swelling and was finally diagnosed with cervical abscess caused by M. tilburgii carrying anti-interferon gamma autoantibodies using a molecular method. The relevant literature was reviewed in the context of epidemiological and clinical data on M. tilburgii infections. In this report, 15 patients were reported to be infected with M. tilburgii. Almost all patients had a cellular immune deficiency and presented with disseminated infections. Multiple refractory or relapse cases that often required prolonged antimycobacterial treatment have been reported, although a few fatal cases have also been reported. In conclusion, M. tilburgii is an important pathogen in patients with cellular immune deficiency. Physicians should thoroughly investigate cellular immune deficiency, including adult-onset immune deficiency with anti-interferon gamma autoantibodies, in patients with M. tilburgii infection.

Non-typhoidal Salmonella bacteremia in COVID-19 with recrudescence of fever after corticosteroid discontinuation: A case report.

It is challenging for clinicians to determine the cause of occurrence of fever in COVID-19 patients after corticosteroid discontinuation. Blood cultures help us distinguish between secondary infections and rebound phenomena. We report a case of non-typhoidal Salmonella bacteremia in a 34-year-old male COVID-19 patient who developed fever after discontinuing corticosteroids.

Imported and locally transmitted mild SARS-CoV-2 pneumonia cases in Japan.

Here, we describe two mild SARS-CoV-2 pneumonia cases. One was imported from Wuhan, and the other was locally transmitted in Japan without recent travel to China. In both cases, lower respiratory tract symptoms were observed first, and high fever progressed in about one week. The laboratory findings revealed normal WBC and CRP despite apparent lung infiltrations, and typical observations on CT imaging were important diagnostic clues. In the domestic endemic situation, a comprehensive evaluation of the clinical course, and laboratory and radiological findings was required for diagnosis.