ABSTRACT
In order to spread systemically, resistance against complement and other factors present in serum is an important trait in pathogenic bacteria. The variable proteins of Mycoplasma agalactiae (Vpmas) have been shown to affect differential adhesion, invasion and immune evasion, and undergo high-frequency phase-variation in expression. However, nothing is known about their involvement in M. agalactiae's serum susceptibility. To evaluate this, the PG2 strain, the GM139 strain and the six Vpma phase-locked mutants (PLMs, PLMU to PLMZ) were tested for their ability to survive in the presence of non-sensitized and sensitized sheep serum, as well as guinea pig complement. Additionally, the reactivity of the sensitized sheep serum was analysed on the strains via western blotting. Overall data demonstrate PG2 strain to be more susceptible to sheep serum compared to the GM139 strain bearing a different Vpma profile. Significant differences were also observed between the different PLMs, with PLMU and PLMX showing the highest serum susceptibility in serum, while the other PLMs expressing longer Vpma proteins were more resistant. The results are in good correlation with previous studies where shorter lipoprotein variants contributed to a higher susceptibility to complement. Since none of the tested strains and PLMs were susceptible to non-sensitized sheep serum, antibodies seem to play an important role in serum killing.
ABSTRACT
The aim of the present study was to investigate the clinical outcomes of two different standardized endodontic irrigation protocols. It was assumed that the additional use of ethylenediaminetetraacetate (EDTA) and passive ultrasonic irrigation (PUI) would result in an increased rate of absence of symptoms and remission based on the periapical index (PAI) compared to passive irrigation using only sodium hypochlorite (NaOCl). Data and radiographs from 199 teeth retrieved from the institutional endodontic database were analyzed retrospectively. In 106 teeth irrigation was performed using only NaOCl (protocol 1). Ninety-three teeth were irrigated using NaOCl and EDTA (protocol 2). Chlorhexidine (CHX) was additionally used in revision treatments in both groups. All irrigants in group 2 were activated by PUI. Mean follow-up periods were: protocol 1 = 9.2 ± 4.4 and protocol 2 = 6.6 ± 2.5 months (p < 0.0001 (chi-square test). The frequencies of the PAImasterpoint and PAIfollow-up scores did not differ significantly between teeth, which received either protocol 1 or 2 (p = 0.555 and 0.138). Statistical analysis revealed no significant association between treatment success (absence of clinical symptoms and PAIfollow-up = I or PAImasterpoint > PAIfollow-up > I) and the applied protocol (success rates: protocol 1 = 72.6% vs. protocol 2 = 82.8%; p = 0.203). Furthermore, the frequency of extractions did not differ significantly between the two protocols (p = 0.102). No association was found between follow-up time and treatment success (p = 0.888). The hypothesis was not confirmed. Even though the obtained success rate was higher after supplementing the irrigation protocol with EDTA and PUI, no significance was recorded. Hence, protocol 2 was not superior to protocol 1 regarding therapy success, at least within the limited follow-up period. It may be cautiously concluded that sufficient mechanical debridement combined with passive NaOCl irrigation results in comparably high success rates compared to EDTA and PUI.
