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.
"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
"In addition, Mycoplasma pneumoniae and Chlamydia species are recognised increasingly as important contributors to the development of chronic lung disease and altered lung maturation[16-19]. New treatable bacteria such as Simkania negevensis (a Chlamydia-like microbe) has been found in Canadian Inuit infants with bronchiolitis. There are no published data on the nature or diversity of respiratory pathogens associated with bronchiolitis in Indigenous Australians infants. "
[Show abstract][Hide abstract] ABSTRACT: Acute lower respiratory infections are the commonest cause of morbidity and potentially preventable mortality in Indigenous infants. Infancy is also a critical time for post-natal lung growth and development. Severe or repeated lower airway injury in very young children likely increases the likelihood of chronic pulmonary disorders later in life. Globally, bronchiolitis is the most common form of acute lower respiratory infections during infancy. Compared with non-Indigenous Australian infants, Indigenous infants have greater bacterial density in their upper airways and more severe bronchiolitis episodes. Our study tests the hypothesis that the anti-microbial and anti-inflammatory properties of azithromycin, improve the clinical outcomes of Indigenous Australian infants hospitalised with bronchiolitis.
We are conducting a dual centre, randomised, double-blind, placebo-controlled, parallel group trial in northern Australia. Indigenous infants (aged ≤ 24-months, expected number = 200) admitted to one of two regional hospitals (Darwin, Northern Territory and Townsville, Queensland) with a clinical diagnosis of bronchiolitis and fulfilling inclusion criteria are randomised (allocation concealed) to either azithromycin (30 mg/kg/dose) or placebo administered once weekly for three doses. Clinical data are recorded twice daily and nasopharyngeal swab are collected at enrollment and at the time of discharge from hospital. Primary outcomes are 'length of oxygen requirement' and 'duration of stay,' the latter based upon being judged as 'ready for respiratory discharge'. The main secondary outcome is readmission for a respiratory illness within 6-months of leaving hospital. Descriptive virological and bacteriological (including development of antibiotic resistance) data from nasopharyngeal samples will also be reported.
Two published studies, both involving different patient populations and settings, as well as different macrolide antibiotics and treatment duration, have produced conflicting results. Our randomised, placebo-controlled trial of azithromycin in Indigenous infants hospitalised with bronchiolitis is designed to determine whether it can reduce short-term (and potentially long-term) morbidity from respiratory illness in Australian Indigenous infants who are at high risk of developing chronic respiratory illness. If azithromycin is efficacious in reducing the morbidly of Indigenous infants hospitalised with bronchiolitis, the intervention would lead to improved short term (and possibly long term) health benefits.
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