Simkania negevensis, an insight into the biology and clinical importance of a novel member of the Chlamydiales order

Abstract

Simkania negevensis is a Chlamydia-related bacterium discovered in 1993 and represents the founding member of the Simkaniaceae family within the Chlamydiales order. As other Chlamydiales, it is an obligate intracellular bacterium characterized by a biphasic developmental cycle. Its similarities with the pathogenic Chlamydia trachomatis and Chlamydia pneumoniae make it an interesting bacterium. So far, little is known about its biology, but S. negevensis harbors various microbiological characteristics of interest, including a strong association of the Simkania-containing vacuole with the ER and the presence of an intron in the 23S rRNA encoding gene. Evidence of human exposition has been reported worldwide. However, there is a lack of robust clinical studies evaluating its implication in human diseases; current data suggest an association with pneumonia and bronchiolitis making S. negevensis a potential emerging pathogen. Owing to its fastidious growth requirements, the clinical relevance of S. negevensis is probably underestimated. In this review, we summarize the current knowledge on S. negevensis and explore future research challenges. ARTICLE HISTORY

Simkania negevensis may produce long lasting infections in human pneumocytes and endometrial cells

“…Our results confirm the large range of hosts harbored by S. negevensis that include mammalian cells, amoebae and arthropods reviewed in (Vouga, Baud and Greub 2016). This dramatically contrasts with the limited host range observed for Chlamydiaceae .…”

“…This suggests that S. negevensis could colonize human respiratory or genital tracts. Congruently, serological evidence of human exposition has been reported worldwide (reviewed in Vouga, Baud and Greub 2016) and an association with lower respiratory tract infections, such as pneumonia and bronchiolitis, is highly suspected (Kahane et al . 1998; Friedman et al .…”

“…2005; Korppi et al . 2006), definite conclusions are difficult to draw due to controversies regarding diagnostic tools’ specificity and risks of PCR contaminations (Vouga, Baud and Greub 2016). Finally, the inhibition of the ER stress by S. negevensis , as well as the presence of the bacterium itself, could act as promoting factors for other infections.…”

Узагальнення Інформації Щодо Хламідійних Інфекцій Тварин Та Їх Зоонозного Потенціалу

“…Chlamydia pecorum пов'язують з енцефалітами, поліартритами, пневмоніями, ентеритами, вагінітами, ендометритами дрібної рогатої худоби; поліартритами, ентеритами, пневмоніями корів; кератокон'юнктивітами, вагінітами, кістами яєчників диких тварин, свиней та безпліддям коал [54,61,79,80]. Bachmann N, Polkinghorne A, et al (2014 р.)…”

What is the true clinical relevance of Simkania negevensis and other emerging Chlamydiales members?

“…Little is known about the biology and the clinical importance of this novel bacterium, but evidence of human exposure has been reported worldwide [5] , with seroprevalence increasing with age, reaching up to 70% to 80% in some Middle Eastern populations [6] , [7] . Several studies have shown an association of acute S. negevensis infection with respiratory diseases, in particular bronchiolitis and pneumonia [5] . Nevertheless, its true clinical relevance remains controversial as a result of the low prevalence of confirmed cases and the low reliability of the diagnostic tools used in most early studies.…”