To determine the prevalence of Simkania negevensis in causing pulmonary infections in children, nasopharyngeal washes were obtained from 22 infants hospitalized with acute bronchiolitis in the Baffin Island, Canada. 14 (63.6%) were positive for S. negevensis. Mixed infections with other respiratory viruses were common. All patients recovered without specific antibiotic treatment. Even though a high prevalence of S. negevensis was found, this organism may potentially well be an opportunistic agent rather than a true pathogen.
"For example, Parachlamydia acanthamoebae is associated with bovine abortions and pneumonia in humans (Borel et al., 2007; Greub 2009), but has also been identified in deer, which may act as wildlife reservoir (Regenscheit et al., 2012). Simkania negevensis has been detected in respiratory infections mostly in children (Friedman, Dvoskin and Kahane 2003; Greenberg et al., 2003), whereas Waddlia chondrophila are found in fetal tissues of humans as well as in bovine abortions (Henning et al., 2002; Dilbeck-Robertson et al., 2003; Wheelhouse et al., 2010; Barkallah et al., 2014). Various members of the Chlamydiales order, especially Parachlamydiaceae , have been located in different aquatic habitats, likely due to the fact that they act as intracellular parasites of free-living amoebae, which are known to be ubiquitous in different environmental niches including fresh and marine waters (Kebbi-Beghdadi and Greub 2014). "
"Seroepidemiological studies from different parts of the world demonstrated remarkable differences in seropositivity rates that range from as low as 4.3% to approximately 80% (Friedman et al., 1999, 2003, 2006; Johnsen et al., 2005; Yamaguchi et al., 2005; Korppi et al., 2006; Donati et al., 2013). In addition, infection with Simkania has been associated with respiratory diseases, such as pneumonia , exacerbation of chronic obstructive pulmonary disease and bronchiolitis (Lieberman et al., 1997, 2002; Kahane et al., 1998; Greenberg et al., 2003; Friedman et al., 2003, 2006; Kumar et al., 2005; Fasoli et al., 2008; Heiskanen-Kosma et al., 2008; Nascimento-Carvalho et al., 2009). However, Niemi and coworkers (2001) were not able to detect an association of Simkania with respiratory diseases. "
[Show abstract][Hide abstract] ABSTRACT: The bacterium Simkania negevensis is a germ associated with respiratory diseases. This study aims at estimating the prevalence of Simkania in the Jordanian population. Serum samples from 664 Jordanian males and females, aged 2 to 86 years were collected. IgG and IgM Simkania-specific antibodies were detected using an indirect immunofluorescence test. Seropositivity titers for IgG and IgM were defined as 1:8 and 1:10, respectively. The overall prevalence of IgG antibody in all examined Jordanian nationals was 58.4%. IgG seropositivity was low in children under the age of 10 years (34.2%), and increased rapidly with age and ranged between 49.4% and 72%. Simkania-specific IgM was detected in 24.8% of subjects. IgM prevalence in children under 10 years was lowest (10.5%) and increased in older ages and remained above 20%. Overall detection rates of both IgG and IgM were significantly higher in females than males (60.7% vs. 54.5% for IgG and 26.7% vs. 21.7% for IgM). These data indicate that Simkania infection is highly prevalent in Jordan. The high level of seropositivity is most likely maintained by re-infections or chronic infections. Our data may serve as a basis to elucidate the pathogenesis of Simkania in Jordan.
"They are obligate intracellular gram-negative bacteria which replicate within endocytic vacuoles of eukaryotic cells i.e. amoebae, human epithelial cells and macrophages . Simkania has been reported as an emerging pathogen associated with several types of respiratory tract infection such as bronchiolitis in infants , , , , community acquired pneumonia , , , chronic obstructive pulmonary disease in adults  and acute rejection in lung transplant recipients . Moreover, seroprevalence rates in adults between 46–80% suggest a broad distribution of the organism in human populations . "
[Show abstract][Hide abstract] ABSTRACT: Control of host cell death is of paramount importance for the survival and replication of obligate intracellular bacteria. Among these, human pathogenic Chlamydia induces the inhibition of apoptosis in a variety of different host cells by directly interfering with cell death signaling. However, the evolutionary conservation of cell death regulation has not been investigated in the order Chlamydiales, which also includes Chlamydia-like organisms with a broader host spectrum. Here, we investigated the apoptotic response of human cells infected with the Chlamydia-like organism Simkania negevensis (Sn). Simkania infected cells exhibited strong resistance to apoptosis induced by intrinsic stress or by the activation of cell death receptors. Apoptotic signaling was blocked upstream of mitochondria since Bax translocation, Bax and Bak oligomerisation and cytochrome c release were absent in these cells. Infected cells turned on pro-survival pathways like cellular Inhibitor of Apoptosis Protein 2 (cIAP-2) and the Akt/PI3K pathway. Blocking any of these inhibitory pathways sensitized infected host cell towards apoptosis induction, demonstrating their role in infection-induced apoptosis resistance. Our data support the hypothesis of evolutionary conserved signaling pathways to apoptosis resistance as common denominators in the order Chlamydiales.
PLoS ONE 07/2011; 6(7):e22528. DOI:10.1371/journal.pone.0022528 · 3.23 Impact Factor
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