Infective endocarditis by Enterobacter cloacae: a systematic review and meta-analysis

Enterobacter species are Gram-negative, non-spore-forming, facultative anaerobes typically motile due to the presence of peritrichous flagella. E. cloacae, the species responsible for the majority of Enterobacter infections in humans, is part of the intestinal microbiota and may cause infection in patients that have previously received antimicrobial therapy or who have been admitted to the Intensive Care Unit. E. cloacae may cause several infections, such as pneumonia, urinary tract, skin and soft tissue and intravascular infections. Infective Endocarditis (IE) is a rare disease with notable morbidity and mortality. Even though IE is rarely caused by E. cloacae, these infections can be problematic due to the relative lack of experience in their management. The purpose of this study was to systematically review all published cases of IE by E. cloacae in the literature. A systematic review of PubMed, Scopus and Cochrane library (through 14^th November 2020) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of IE by E. cloacae was performed. A total of 20 studies, containing data of 20 patients, were included. A prosthetic valve was present in 27.8%. Mitral valve was the commonest infected site, followed by aortic valve. Diagnosis was facilitated by transthoracic and transesophageal echocardiography in 38.5% each, while the diagnosis was set at autopsy in 10%. Fever, sepsis, shock and immunologic phenomena were the most common clinical presentations, followed by heart failure. Aminoglycosides, cephalosporins and carbapenems were the most common antimicrobials used. Clinical cure was noted in 75%, while overall mortality was 30%. Development of shock and treatment with the combination of piperacillin with tazobactam were associated with overall mortality.

Rare Variants in BNC2 Are Implicated in Autosomal-Dominant Congenital Lower Urinary-Tract Obstruction

Congenital lower urinary-tract obstruction (LUTO) is caused by anatomical blockage of the bladder outflow tract or by functional impairment of urinary voiding. About three out of 10,000 pregnancies are affected. Although several monogenic causes of functional obstruction have been defined, it is unknown whether congenital LUTO caused by anatomical blockage has a monogenic cause. Exome sequencing in a family with four affected individuals with anatomical blockage of the urethra identified a rare nonsense variant (c.2557C>T [p.Arg853^∗]) in BNC2, encoding basonuclin 2, tracking with LUTO over three generations. Re-sequencing BNC2 in 697 individuals with LUTO revealed three further independent missense variants in three unrelated families. In human and mouse embryogenesis, basonuclin 2 was detected in lower urinary-tract rudiments. In zebrafish embryos, bnc2 was expressed in the pronephric duct and cloaca, analogs of the mammalian lower urinary tract. Experimental knockdown of Bnc2 in zebrafish caused pronephric-outlet obstruction and cloacal dilatation, phenocopying human congenital LUTO. Collectively, these results support the conclusion that variants in BNC2 are strongly implicated in LUTO etiology as a result of anatomical blockage.