Amoxicillin resistance with beta-lactamase production in Helicobacter pylori.

BACKGROUND: Amoxicillin-resistant Helicobacter pylori with minimal inhibitory concentration (MIC) >or= 256 mg L(-1) was isolated from a gastritis patient. The aims were to investigate the mechanism of high-level amoxicillin resistance in H. pylori. MATERIALS AND METHODS: The beta-lactamase production was determined by means of nitrocefin sticks and the presence of gene encoding the beta-lactam antibiotic resistance enzyme TEM beta-lactamase was analysed by polymerase chain reaction (PCR), sequencing and dot-blot hybridization. Sequencing analysis of pbp1A gene was performed and amoxicillin-susceptible isolate was transformed with pbp1A PCR products from the resistant isolate. The expression of hefC efflux system was analysed using real-time quantitative PCR. RESULTS: Activity of beta-lactamase was detected. Sequence analysis showed that the PCR product derived from H. pylori 3778 was identical to the bla(TEM-1) (GenBank accession EU726527). Dot-blot hybridization confirmed the presence of beta-lactamase gene bla(TEM-1.) By transformation of PCR product of mutated pbp1A gene from H. pylori 3778 into amoxicillin-susceptible strain showed that substitutions in Thr(556)-->Ser, Lys(648)-->Gln, Arg(649)-->Lys and Arg(656)-->Pro contribute to low-level amoxicillin resistance. The MIC of amoxicillin for the transformants was 0.75 mg L(-1). Over-expression of hefC was not found. CONCLUSIONS: High-level amoxicillin resistance is associated with beta-lactamase production in H. pylori. Low-level amoxicillin resistance is linked to a point mutation on pbp1A. Because H. pylori can exchange DNA through natural transformation, spreading of bla(TEM-1) amoxicillin resistance gene among H. pylori is a potential threat when treating H. pylori infection.

Comparison of cutaneous tolerance and efficacy of calcitriol 3 microg g(-1) ointment and tacrolimus 0.3 mg g(-1) ointment in chronic plaque psoriasis involving facial or genitofemoral areas: a double-blind, randomized controlled trial.

BACKGROUND: Two nonsteroidal topical agents, calcitriol and tacrolimus, have been reported to be effective and safe for psoriatic lesions on sensitive areas. However, no comparative studies between calcitriol and tacrolimus have been reported. OBJECTIVES: To compare the tolerability and efficacy of calcitriol 3 microg g(-1) and tacrolimus 0.3 mg g(-1) ointment in chronic plaque psoriasis affecting facial and genitofemoral regions. METHODS: This is a double-blind, parallel, 6-week study of 50 patients who were randomized in a 1 : 1 ratio to apply calcitriol or tacrolimus twice daily. The primary efficacy variable was the mean reduction of the target area score (TAS), and the secondary efficacy variable was the percentage of patients with the Physician's Global Assessment (PGA) score of 5 (clear) and 4 (almost clear) at the end of the study. RESULTS: Both calcitriol and tacrolimus were well tolerated. Although calcitriol induced perilesional erythema in a statistically significant higher proportion of patients than tacrolimus (55% vs. 16% at week 6; P < 0.05), it did not necessitate treatment discontinuation. At the end of the study, tacrolimus was significantly more effective than calcitriol based on a significant reduction of mean TAS (67% vs. 51%; P < 0.05) as well as more patients achieving complete or almost complete clearance by PGA (60% vs. 33%; P < 0.05). CONCLUSIONS: Both calcitriol 3 microg g(-1) and tacrolimus 0.3 mg g(-1) are safe and well-tolerated therapeutic agents in the treatment of psoriasis in sensitive areas. Tacrolimus demonstrated a more effective clinical outcome compared with calcitriol.

Cloning, sequencing, and expression of the rpoD gene encoding the primary sigma factor of Xanthomonas campestris.

A DNA fragment encoding the primary sigma factor from Xanthomonas campestris pv. campestris was cloned and sequenced. The gene (rpoD) encodes a polypeptide of 622 amino acids with a calculated MW of 70,700. The deduced amino acid sequence exhibits extensive sequence homology to the conserved regions of the primary sigma factors from bacteria. The gene product expressed in Escherichia coli, detected by Western blot analysis, had a MW similar to that estimated for the purified protein in SDS-PAGE. The NH2-terminal amino acid sequence determined chemically matched with that deduced from the nucleotide sequence of the rpoD gene. The calculated pI value (9.31) for the X. campestris primary sigma factor is much higher than the values observed for the analogous proteins from other bacteria.