Abstract
The etiological agent for infective endocarditis (IE), a life-threatening disease, is usually gram-positive bacteria. However, gram-negative bacteria can rarely cause IE and 4% of cases are associated with morbidity and mortality. This study aimed to characterize Escherichia coli and Klebsiella pneumoniae isolates from the blood of patients with IE. The characteristics of blood isolates were compared with those of urinary isolates from patients with urinary tract infections (UTIs). The results of this study revealed that K. pneumoniae isolates from patients with IE were phylogenetically related to those from patients with UTI. Additionally, the resistance phenotype, resistance gene, virulence gene, and plasmid profiles were similar between the blood and urinary isolates. The isolates belonging to the sequence types (STs) 76, 36, 101 (K. pneumoniae), and 69 (E. coli) are reported to be associated with drug resistance. The Enterobacteriaceae isolates from patients with IE did not produce extended-spectrum β-lactamase or carbapenemase. Additionally, this study investigated the virulence phenotype, biofilm formation ability, and the ability to adhere to the epithelial cells in vitro of the isolates. The isolates from patients with IE exhibited weaker biofilm formation ability than the urinary isolates. All isolates from patients with IE could adhere to the renal epithelial cells. However, three isolates from patients with UTIs could not adhere to the epithelial cells. The closely related K. pneumoniae isolates (648, KP1, KP2, KP3, and KP4) could not form biofilms or adhere to the epithelial cells. In summary, the molecular analysis revealed that the genetic characteristics of IE-causing K. pneumoniae and E. coli were similar to those of UTI-causing isolates. These isolates belonged to the STs that are considered treatable. Genetically similar isolates did not exhibit the same virulence phenotype. Thus, these non-hypervirulent clones must be monitored as they can cause complex infections in susceptible hosts.
Highlights
Infective endocarditis (IE), a systemic life-threatening infection, requires a multidisciplinary therapeutic strategy [1, 2]
This study aimed to comparatively analyze the molecular characteristics of E. coli and K. pneumoniae isolated from the blood of patients with IE in Rio de Janeiro, Brazil, with those of other pathogens isolated from the urine of hospitalized patients with urinary tract infections (UTIs)
The results of this study revealed similarities between the blood E. coli isolate from a patient with IE and a urinary isolate belonging to the same sequence types (STs)
Summary
Infective endocarditis (IE), a systemic life-threatening infection, requires a multidisciplinary therapeutic strategy [1, 2]. Endocarditis is the fourth most common life-threatening infectious syndrome after urosepsis, pneumonia, and intraabdominal sepsis in the medical facilities of developed countries [3]. There is an increased incidence of invasive infections caused by E. coli and K. pneumoniae [7,8,9]. The treatment of E. coli and K. pneumoniae infections is challenging owing to the development of multidrug resistance in the pathogens [10, 11]. Drug resistance is a major challenge to treat virulent gram-negative bacterial infections [5, 7]. The pathological mechanisms of IE caused by the members of the family Enterobacteriaceae have not been completely elucidated [2,3,4,5]
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