Changes in lipopolysaccharide profile of Porphyromonas gingivalis clinical isolates correlate with changes in colony morphology and polymyxin B resistance.

Virulence factors on the surface of Porphyromonas gingivalis constitute the first line of interaction with host cells and contribute to immune modulation and periodontitis progression. In order to characterize surface virulence factors present on P. gingivalis, we obtained clinical isolates from healthy and periodontitis subjects and compared them with reference strains. Colony morphology, aggregation in liquid medium, surface charge, membrane permeability to bactericidal compounds, novobiocin and polymyxin B resistance, capsule presence and lipopolysaccharide (LPS) profiles were evaluated. By comparing isolates from healthy and periodontitis subjects, differences in colony morphology and aggregation in liquid culture were found; the latter being similar to two reference strains. These differences were not a consequence of variations in bacterial surface charge. Furthermore, isolates also presented differences in polymyxin B and novobiocin resistance; isolates from healthy subjects were susceptible to polymyxin B and resistant to novobiocin and, in contrast, isolates from periodontitis subjects were resistant to polymyxin B and susceptible to novobiocin. These changes in antimicrobial resistance levels correlate with variations in LPS profiles, since -unlike periodontitis isolates-isolates from healthy samples synthesize LPS molecules lacking both O-antigen moieties and anionic polysaccharide. Additionally, this phenotype correlated with the absence of O-antigen ligase activity. Altogether, our results reveal novel variations on surface components of P. gingivalis isolates obtained from healthy and periodontitis subjects that could be associated with differences in bacterial virulence and periodontitis progression.

Growth hormone/JAK-STAT axis signal-transduction defect. A novel treatable cause of growth failure.

Primary cultured fibroblasts of four patients with idiopathic short stature and severe growth delay, which displayed normal growth hormone receptor expression presented a reduced ability for activation of signal transducer and activator of transcription-3 (STAT3). Impaired STAT3 activation was accompanied by cell-cycle arrest at the Go /G1 phase. Increased levels of the cyclin-dependent kinase inhibitor, p21(WAF/CIPI), and reduced levels of cyclins were also detected in these patients. High concentrations of human growth hormone (1000 ng x mL(-1)) added to the culture medium induced activation of STAT3 and reduced the levels of p21(WAF/CIPI) in the fibroblasts of the four idiopathic short stature children. Treatment of these children with exogenous human growth hormone significantly augmented their growth velocity. Overall, our study provides the first evidence linking the idiopathic short stature phenotype with a functional aberration in the growth hormone signal transduction cascade which can be successfully overcome by exposure to high doses of growth hormone.

Frequency and antimicrobial sensitivity of Ureaplasma urealyticum and Mycoplasma hominis in patients with vaginal discharge.

Determination of antimicrobial sensitivity helps establish adequate treatment and avoids future genital tract diseases in women of fertile age. In Cuba, prevalence of mycoplasma in patients with vaginal discharge is unknown. The objective of this research was to determine frequency and antimicrobial sensitivity of Ureaplasma urealyticum and Mycoplasma hominis in women with vaginal discharge through analysis of laboratory data from vaginal smears from 255 patients referred to the Municipal Hygiene and Epidemiology Center in Güines, Mayabeque Province, Cuba. Mycoplasma System Plus (Italy) was used for detection, identification, count and sensitivity testing. The finding of mycoplasmas in almost two thirds of specimens examined suggests that the sexually active female population should be screened for these bacteria and that barrier contraception methods should be promoted to decrease their spread and prevent longterm sequelae. Such updating of local patterns of antimicrobial resistance supports decision making for best treatment options in patients with these infections. Our results should help clinicians in our area choose an antibiotic, and also confirm the utility of Mycoplasma System Plus for mycoplasma research in resource-scarce settings, to benefit individual and population health.