Introduction  In the ongoing severe acute respiratory syndrome coronavirus 2 pandemic, a long hospital stay and empirical broad-spectrum antibiotics make the patients prone to acquire nosocomial infections especially with unconventional organisms, and Chryseobacterium gleum is one such rare nosocomial pathogen. Methods  The given study is a case-series-based study conducted from September 2020 to April 2021 in which clinically suspected pneumonia patients who recovered from coronavirus disease 2019 (COVID-19) were included. Results  Seventeen C. gleum isolates were obtained in pure culture from the tracheal aspirates of nine COVID-19 patients (including repeat samples to rule out colonization) within a period of eight months (September 2020-April 2021). Our records showed that there has been an increase in the number of isolates of C. gleum obtained in respiratory samples in 2020. We also did a review of literature of all the cases of C. gleum pneumonia reported till now. Conclusion  To the best of our knowledge, this is the first study reporting the isolation of this rare pathogen from COVID-19 patients with clinical significance in a large cohort of patients. Therefore, it becomes important to consider this pathogen as a significant cause of respiratory infections, especially in patients recovered post COVID-19.

Chryseobacterium species are recognized as an emerging opportunistic bacterial pathogen in nosocomial settings especially in debilitated or immunosuppressed patients and neonates. The ubiquitous distribution in nature, ability to form biofilms with inherent resistance to broad-spectrum antimicrobials, and lack of clinical studies pose a further diagnostic and therapeutic challenge. This case report describes an elderly male with relapsed diffuse large B-cell lymphoma (DLBCL) status post-chemotherapy and radiation who acquired healthcare-associated pneumonia with sputum isolates showing Chryseobacterium gleum and Stenotrophomonas maltophila. It also includes a review of literature compiling all the previously reported cases with antibiotic susceptibilities, clinical picture, and treatment outcomes.

Chryseobacterium gleum is a Gram-negative aerobic bacillus. It commonly colonizes mechanical devices, causing device-associated infections like central line-associated bloodstream infection and ventilator-associated pneumonia. We describe two cases of C. gleum bacteraemia in patients admitted to our intensive care unit in Qatar, one of which resulted in death. Long hospital stays and indwelling devices are risk factors for C. gleum bacteraemia. Because C. gleum is inherently resistant to β-lactam antibiotics, rapid identification and antimicrobial susceptibility testing are essential for guiding therapy.

Chryseobacterium species are widely distributed in the environment. They are rarely found in hospital settings causing nosocomial infections. Limited data is available regarding their epidemiology, clinical significance and antimicrobial susceptibility patterns. This study was aimed to identify different species of Chryseobacterium using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and to correlate clinically with antimicrobial susceptibility patterns in a tertiary care hospital in north India. We also performed phenotypic tests, which may be useful to differentiate this bacterium from other non-fermenters. A total of 20 isolates of Chryseobacterium spp. were identified over a period of 3 years. Chryseobacterium indologenes (18/20) was the most common species isolated followed by Chryseobacterium gleum (2/20) from various clinical samples. Antimicrobial susceptibility testing (AST) was performed. Susceptibility to rifampicin was observed at a maximum (75%) followed by piperacillin-tazobactum (45%). Susceptibility against imipenem, meropenem, cotrimoxazole and cefoperazone-sulbactum were observed approximately 33%. Amikacin, cefotaxime and ceftazidime showed least susceptibility results. Further clinical correlation was established.

Chryseobacterium indologenes and Chryseobacterium gleum are Gram negative environmental bacteria that have been frequently reported to implicate in fatal nosocomial infections, such as bacteraemia and ventilator-associated pneumonia in immunocompromised individuals in the past decades. The interaction between Chryseobacterium spp. and Acanthamoeba castellanii, a free-living amoeba ubiquitous in the environment, has not been explored previously. In this study, C. indologenes and C. gleum were co-cultured with A. castellanii trophozoites and their interactions were evaluated. Our results showed that when co-cultured with A. castellanii, bacterial numbers of C. indologenes and C. gleum increased significantly (p < 0.05), indicating growth-supporting role of A. castellanii. Specifically, our findings showed that C. indologenes and C. gleum were able to associate, invade and/or taken up by A. castellani trophozoites, and multiply intracellularly at similar rates (p > 0.05). Interestingly, the two Chryseobacterium spp. associated, invaded and/or taken up by A. castellanii at significantly higher rates than Escherichia coli K1, a neuropathogenic bacterial strain known to interact and replicate intracellularly in A. castellanii (p < 0.05). However, the ability of both Chryseobacterium spp. to multiply in A. castellanii was significantly weaker than E. coli K1 (p < 0.001). This is the first time that Chryseobacterium spp. and A. castellanii were shown to interact with each other. The ability to survive intracellularly in A. castellanii may confer protection to C. indologenes and C. gleum and assist in the survival and transmission of Chryseobacterium spp. to susceptible hosts within a hospital setting. Future studies will determine the ability of C. indologenes and C. gleum survival in A. castellanii cysts and the possible molecular mechanisms involved in such interactions.

Introduction. Species of the genus Chryseobacterium are emerging healthcare-associated pathogens, often colonizing the hospital environment. There are no clear guidelines available for antimicrobial susceptibility of this organism. In this report we present the first case, to our knowledge, of simultaneous central-line-associated bloodstream infection (CLABSI) and ventilator-associated pneumonia (VAP) due to Chryseobacterium gleum from India. Case presentation. A 62 years old man with a history of a road traffic accident 1 month previously was referred to our center for further management. He developed features of sepsis and aspiration pneumonia on day 3 of admission. Four blood cultures (two each from central and peripheral lines) and two tracheal aspirate cultures grew pure yellow colonies of bacteria. Both matrix assisted laser desorption ionization time of flight mass spectrometry, (MALDI-TOF MS; bioMérieux, Marcy-L\'Etoile, France,) and BD Phoenix (BD Biosciences, Maryland, USA) identified the organism as C. gleum. However, BD Phoenix failed to provide MIC breakpoints. The isolates of C. gleum both from blood and tracheal aspirate showed identical susceptibility patterns: resistant to cephalosporins and carbapenems and susceptible to ciprofloxacin, levofloxacin, amikacin, trimethoprim+sulfamethoxazole, piperacillin-tazobactam, cefoperazone-sulbactam, doxycycline, minocycline and vancomycin. Following levofloxacin therapy, the fever responded within 48 h and procalcitonin levels decreased without removal of the central line or endotracheal tube. However, the patient developed sudden cardiac arrest on day 10 of treatment and could not be resuscitated. Conclusion. Rapid and accurate identification of C. gleum in the laboratory, preferably based on MALDI-TOF, is essential for guiding therapy. C. gleum responds well to fluoroquinolones without the need to remove indwelling catheters.

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Chryseobacterium gleum is commonly distributed in the environment. It can cause a wide variety of infections in immunocompromised patients in hospital setting.
A 6 month old infant with nephrotic syndrome was admitted to the emergency room for an acute onset of fever, difficulty breathing, cyanosis, and low oral intake. Cultures of endotracheal tube specimens were positive for Chryseobacterium gleum which was confirmed by ribosomal sequencing. The organism was susceptible to trimethoprim-sulfamethoxazole, minocycline, and levofloxacin. The patient clinically improved on levofloxacin treatment.
To the best of our knowledge, this is the first case of pneumonia caused by Chryseobacterium gleum in an infant with nephrotic syndrome. It is also the first report of C. gleum causing respiratory tract infection in Saudi Arabia.

Chryseobacterium gleum is not commonly isolated from clinical source(s). Using 16S rRNA gene sequencing, we identified 15 C. gleum isolates from the Central Region Hospital Alliance, Taiwan, which were all misidentified: 14 as Chryseobacterium indologenes and 1 as Elizabethkingia meningoseptica using the Vitek 2 GN card. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, a rapid and clinically applicable method, was evaluated for the identification of C. gleum, and the rate of species or probable species level identification reached 13.3% and 86.6%, respectively. Using pulsed-field gel electrophoresis analysis, all C. gleum isolates from central Taiwan were found to be epidemiologically unrelated. The most prevalent sample was urine (35.7%, 5/14), followed by sputum (28.6%, 4/14), whereas 1 isolate was from an unknown source. All of the isolates were susceptible to minocycline, 93.3% susceptible to trimethoprim/sulfamethoxazole, but were completely or highly resistant to the other drugs examined. Biofilm-forming ability was observed in 40.0% (6/15) isolates using the Luria-Bertani broth. To the best of our knowledge, this is the first focusing on exploring clinical C. gleum isolates.