Background: A commercial rapid urinay pneumococcal antigen test (Binax NOW, Porland, USA) that detects the C polysaccharide antigen present in all Streptococcus pneumoniae is used in diagnosis of pneumococcal infection. Additionally to, studies report that children with nasopharyngeal carriage of streptococcus pneumoniae had high rates of positive test results due to pneumococal antigen reactions.We aimed to evaluate the Binax NOW urinary antigen test in healthy children and determined the influence of nasopharyngeal pneumococcal carriage on the results of the antigen detection test. Methods: The study was performed on healthy children and recevied routine clinical care at Ege University Medicine Faculty Health Child Policlinic, between September 2009 and March 2010. All of the children enrolled and provided both nasopharyngeal swab specimens for culture and urine samples for the antigen detection test. Results: Our study included 205 children, ages between 2-60 months, 122 (60%) males and 83 (40%) females. All of the children were vaccined with 7 valent-pneumococcal conjugate vaccine. Pneumococcal nasopharyngeal carriage was present in 24 (10.8%) of 223. In 16 of 24 (%66.7) nasopharyngeal carriage children, pneumococ antigen was determined positive in their urine samples with the Binax NOW test. Also in 17 of 199 (%8.5) non nasopharyngeal pneumococ carriage children, pneumococ antigen was determined positive in urine samples. (p < 0.001). The urine antigen detection test was significantly more likely to indicate a positive result for patients who were nasopharyngeal carriers of pneumococci than for those who were not. Conclusion: Binax NOW test can't be useful to diagnose pneumococ infection in children because the test can be positive in the children who are nasopharyngeal carriers. In that situation it can be more sensitive to use other rapid diagnosis tests.
Aspects of how Burkholderia escape the host's intrinsic immune response to replicate in the cell cytosol remain enigmatic. Here, we show that Burkholderia has evolved two mechanisms to block the activity of Ring finger protein 213 (RNF213)-mediated non-canonical ubiquitylation of bacterial lipopolysaccharide (LPS), thereby preventing the initiation of antibacterial autophagy. First, Burkholderia's polysaccharide capsule blocks RNF213 association with bacteria and second, the Burkholderia deubiquitylase (DUB), TssM, directly reverses the activity of RNF213 through a previously unrecognized esterase activity. Structural analysis provides insight into the molecular basis of TssM esterase activity, allowing it to be uncoupled from its isopeptidase function. Furthermore, a putative TssM homolog also displays esterase activity and removes ubiquitin from LPS, establishing this as a virulence mechanism. Of note, we also find that additional immune-evasion mechanisms exist, revealing that overcoming this arm of the host's immune response is critical to the pathogen.
Abstract Pathogenic bacteria have evolved diverse mechanisms to counteract cell-autonomous immunity, which otherwise guards both immune and non-immune cells from the onset of an infection 1,2 . The versatile immunity protein Ring finger protein 213 (RNF213) 3–6 mediates the non-canonical ester-linked ubiquitylation of lipopolysaccharide (LPS), marking bacteria that sporadically enter the cytosol for destruction by antibacterial autophagy 4 . However, whether cytosol-adapted pathogens are ubiquitylated on their LPS and whether they escape RNF213-mediated immunity, remains unknown. Here we show that Burkholderia deubiquitylase (DUB), TssM 7–9 , is a potent esterase that directly reverses the ubiquitylation of LPS. Without TssM, cytosolic Burkholderia became coated in polyubiquitin and autophagy receptors in an RNF213-dependent fashion. Whereas the expression of TssM was sufficient to enable the replication of the non-cytosol adapted pathogen Salmonella, we demonstrate that Burkholderia has evolved a multi-layered defence system to proliferate in the host cell cytosol, including a block in antibacterial autophagy 10–12 . Structural analysis provided insight into the molecular basis of TssM esterase activity, allowing it to be uncoupled from isopeptidase function. TssM homologs conserved in another Gram-negative pathogen also reversed non-canonical LPS ubiquitylation, establishing esterase activity as a bacterial virulence mechanism to subvert host cell-autonomous immunity.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
