A fatal case of early prosthetic valve endocarditis caused by multidrug-resistant (MDR) - Sphingomonas paucimobilis

Bacterial Diversity in Native Heart Valves in Infective Endocarditis

Background: Infective endocarditis (IE) is an infectious disease caused by the hematogenous dissemination of bacteria into heart valves. Improving the identification of pathogens that cause IE is important to increase the effectiveness of its therapy and reduce the mortality caused by this pathology. Methods: Ten native heart valves obtained from IE patients undergoing heart valve replacements were analyzed. Bacterial invasion in the heart valves was studied by Gram staining of histological sections. Histopathological changes accompanied with bacterial invasion were studied by immunohistochemical analysis of pan-leukocyte marker CD45, platelet marker CD41, and neutrophil myeloperoxidase. The taxonomic diversity of the bacteria was analyzed using 16S rRNA metabarcoding. Results: Gram staining of the histological sections revealed bacterial cells localized on the atrial surface at the leaflet's free edge or on the ventricular surface at the leaflet's base within fibrin deposits in only three of the studied heart valves. Bacterial colonies were co-localized with microthrombi (CD41+ cells) containing single leucocytes (CD45+ cells), represented by segmented neutrophils. As a result of 16S rRNA metabarcoding, we detected the following bacterial genera: Pseudomonas (70% of the studied heart valves), Roseateles (60%), Acinetobacter (40%), Sphingomonas (40%), Enterococcus (30%), Reyranella (20%), Sphingobium (20%), Streptococcus (20%), Agrobacterium (20%), Ralstonia (10%), and Bacillus (10%). Conclusions: A number of opportunistic microorganisms that could not be detected by routine laboratory tests and were not eliminated during antibiotic therapy were identified in the IE-affected heart valves. The obtained results show the importance of 16S rRNA metabarcoding of heart valves removed due to IE not only as an independent diagnostic method but also as a highly accurate approach that complements routine tests for pathogen identification.

A nostoxanthin-producing bacterium, Sphingomonas nostoxanthinifaciens sp. nov., alleviates the salt stress of Arabidopsis seedlings by scavenging of reactive oxygen species

A novel, nostoxanthin-producing, endophytic bacterium, designated as AK-PDB1-5^T, was isolated from the needle-like leaves of the Korean fir (Abies koreana Wilson) collected from Mt. Halla in Jeju, South Korea. A 16S rRNA sequence comparison indicated that the closest phylogenetic neighbors were Sphingomonas crusticola MIMD3^T (95.6%) and Sphingomonas jatrophae S5-249^T (95.3%) of the family Sphingomonadaceae. Strain AK-PDB1-5^T had a genome size of 4,298,284 bp with a 67.8% G + C content, and digital DNA-DNA hybridization and OrthoANI values with the most closely related species of only 19.5-21% and 75.1-76.8%, respectively. Cells of the strain AK-PDB1-5^T were Gram-negative, short rods, oxidase- and catalase-positive. Growth occurred at pH 5.0-9.0 (optimum pH 8.0) in the absence of NaCl at 4-37°C (optimum 25-30°C). Strain AK-PDB1-5^T contained C_14:0 2OH_, C_16:0 and summed feature 8 as the major cellular fatty acids (> 10%), while sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, phospholipids and lipids were found to be the major polar lipids. The strain produces a yellow carotenoid pigment; natural products prediction via AntiSMASH tool found zeaxanthin biosynthesis clusters in the entire genome. Biophysical characterization by ultraviolet-visible absorption spectroscopy and ESI-MS studies confirmed the yellow pigment was nostoxanthin. In addition, strain AK-PDB1-5^T was found significantly promote Arabidopsis seedling growth under salt conditions by reducing reactive oxygen species (ROS). Based on the polyphasic taxonomic analysis results, strain AK-PDB1-5^T was determined to be a novel species in the genus Sphingomonas with the proposed name Sphingomonas nostoxanthinifaciens sp. nov. The type strain is AK-PDB1-5^T (= KCTC 82822^T = CCTCC AB 2021150^T).

Sphingomonas paucimobilis native valve endocarditis and mycotic cerebral aneurysm in a patient with Crohn's disease: Case report and review of literature

This report describes a case of Sphingomonas paucimobilis bacteremia and infective endocarditis with a mycotic aneurysm in a young patient with Crohn's disease. Our patient reported prolonged intermittent fever followed by sudden hemiparesis and a tonic clonic convulsion. His blood cultures showed growth of Sphingomonas paucimobilis, and further cardiac imaging revealed the presence of a vegetation with severe valvular regurgitation. Cerebral angiography showed middle cerebral artery occlusion and aneurysm. The patient was treated with meropenem for 6 weeks, coupled with aortic valve replacement, and coiling of the aneurysm. Our patient recovered with good results. S. paucimobilis is an opportunistic gram-negative pathogen of growing importance in the clinical setting.

Resistance determinants of emerging pathogens isolated from an intensive care unit as a parameter of population health conditions of the Legal Amazon microregion

Abstract Bacteria responsible for causing infections are common in hospital environments, water, soil, and food products. The infection risk is intensified by the absence of public sanitation, poor quality of life, and food scarcity. These external factors promote the dissemination of pathogens by direct contamination or biofilm formation. In this work, we identified bacterial isolates obtained from intensive care units in the southern region of Tocantins, Brazil. We compared matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) techniques and 16S ribosomal ribonucleic acid (rRNA) molecular analysis; we also performed phenotypic characterization. Fifty-six isolates characterized using morphotinctorial tests were classified as gram-positive (80.4%; n = 45) and gram-negative (19.6%; n = 11) and were resistant to several antibiotic classes; notably, we identified the blaOXA-23 resistance gene in the ILH10 isolate. Microbial identification using MALDI-TOF MS resulted in the identification of Sphingomonas paucimobilis and Bacillus circulans. 16S rRNA sequencing revealed four isolates belonging to the genera Bacillus and Acinetobacter. The similarity was superior to 99% for Acinetobacter schindleri in the Basic Local Alignment Search Tool (BLAST), grouped in the clade superior to 90%. Several strains isolated from intensive care units (ICU) were resistant to various antibiotic classes. These techniques allowed for the identification of several microorganisms of importance in public health, enabling improvements in human infection control and proving the quality of inputs, food, and water.

Cupriavidus spp and other waterborne organisms in healthcare water systems across the United Kingdom

BACKGROUND

Cupriavidus pauculus is a rare clinical pathogen with cases having been linked to contaminated hospital water systems. An outbreak of three cases of C. pauculus and other waterborne organisms was reported in a Glasgow hospital in 2018.

AIMS

The aim of this study was to determine whether Cupriavidus spp are present in hospital water systems elsewhere in Scotland and the UK and to ascertain the optimal laboratory methodology for detection. We also sought to establish where in the water system these organisms are detected and whether a selective media could be developed for isolation. In addition, we tested water samples for the presence of other Gram negative waterborne organisms.

METHODS

Water samples were received from ten UK NHS hospitals and from various parts of the water system. Isolates were plated on to TSA and Pseudomonas Isolation Agar and further identified using MALDI-TOF and 16S PCR FINDINGS: Cupriavidus spp. were detected in four of ten hospitals tested and all five isolates were from the periphery of the water system. All hospitals had evidence of other OPPPs. Cupriavidus spp. were identified using TSA, with some isolates growing on Pseudomonas isolation agar; as such they may be inadvertently be detected when testing water specifically for Pseudomonas aeruginosa.

CONCLUSION

This study demonstrates that isolation of Cupriavidus spp. was not unique to the Glasgow incident, these bacteria being present in hospital water systems elsewhere in the UK. We therefore recommend water testing in response to clinical cases. Consideration should also be given to water testing following bacteraemias due to other rare and unusual water borne pathogens.

Gram-negative endocarditis: disease presentation, diagnosis and treatment

PURPOSE OF REVIEW

Gram-negative bacilli (GNB) cause between 1% and 10% of infective endocarditis (IE). Most episodes are caused by microorganisms of the Haemophilus spp., Aggregatibacter spp. Cardiobacterium spp., Eikenella spp., and Kingella spp (HACEK) group. The frequency of IE caused by non-HACEK (GNB-IE) has increased in recent years. Uncertainties persist regarding its best medical treatment and the appropriateness and timing of surgical treatment. In addition, there are new drugs with activity against multiresistant microorganisms, of which there is little experience in this disease. We review this topic by answering the most frequently asked questions that arise among our colleagues.

RECENT FINDINGS

HACEK microorganisms cause 1.5-2% of IE with only a 2% mortality. In contrast, non-HACEK GNB-IE accounts for 2.5-3% of all IE cases and is associated with nosocomial acquisition, advanced age, solid organ transplantation and 20-30% mortality. Drug addiction is important in areas with epidemic opioid abuse.

SUMMARY

The frequency of IE caused by GNB has been modified in recent years. HACEK episodes are no longer treated with ampicillin and aminoglycosides. In non-HACEK GNB-IE, combination therapy with a beta-lactam and a quinolone or aminoglycoside is recommended. The surgical indication and its value are evident in many patients. Management should rely on a collaborative group with experience in this disease.