Mechanisms of Helicobacter pylori antibiotic resistance: An updated appraisal

Multidrug Efflux Systems in Helicobacter cinaedi

Helicobacter cinaedi causes infections, such as bacteremia, diarrhea and cellulitis in mainly immunocompromised patients. This pathogen is often problematic to analyze, and insufficient information is available, because it grows slowly and poorly in subculture under a microaerobic atmosphere. The first-choice therapy to eradicate H. cinaedi is antimicrobial chemotherapy; however, its use is linked to the development of resistance. Although we need to understand the antimicrobial resistance mechanisms of H. cinaedi, unfortunately, sufficient genetic tools for H. cinaedi have not yet been developed. In July 2012, the complete sequence of H. cinaedi strain PAGU 611, isolated from a case of human bacteremia, was announced. This strain possesses multidrug efflux systems, intrinsic antimicrobial resistance mechanisms and typical mutations in gyrA and the 23S rRNA gene, which are involved in acquired resistance to fluoroquinolones and macrolides, respectively. Here, we compare the organization and properties of the efflux systems of H. cinaedi with the multidrug efflux systems identified in other bacteria.

Growth-inhibiting, bactericidal, and urease inhibitory effects of Paeonia lactiflora root constituents and related compounds on antibiotic-susceptible and -resistant strains of Helicobacter pylori

An assessment was made of the growth-inhibiting, bactericidal, and urease inhibitory activities of paeonol (PA), benzoic acid (BA), methyl gallate (MG), and 1,2,3,4,6-penta-O-galloyl-β-d-glucopyranose (PGG) identified in Paeonia lactiflora root, structurally related compounds, and four antibiotics toward three reference strains and four clinical isolates of Helicobacter pylori using broth dilution bioassay and Western blot. BA and PA showed strong bactericidal effect at pH 4, while MG and PGG were effective at pH 7. These constituents exhibited strong growth-inhibiting and bactericidal activity toward the five strains resistant to amoxicillin (minimal inhibitory concentration (MIC) 12.5 mg/L), clarithromycin (64 mg/L), metronidazole (64 mg/L), or tetracycline (15 mg/L), indicating that these constituents and the antibiotics do not share a common mode of action. Structural characteristics, such as types of functional groups and carbon skeleton, and hydrophobicity appear to play a role in determining the anti- H. pylori activity. H. pylori urease inhibitory activity of PGG was comparable to that of acetohydroxamic acid, while MG was less potent at inhibiting urease than thiourea. The UreB band disappeared at 250 mg/L PGG on Western blot, while the UreA bands were faintly visible at 1000 mg/L PGG. These constituents showed no significant cytotoxicity. Global efforts to reduce the level of antibiotics justify further studies on P. lactiflora root-derived materials containing MG, PA, and PGG as potential antibacterial products or lead molecules for the prevention or eradication from humans from diseases caused by H. pylori .

[Helicobacter pylori eradication frequency with the conventional triple therapy in adult patients at the Centro Médico Issemym]

BACKGROUND

In Mexico, the prevalence of Helicobacter pylori (H. pylori) infection is high. The bacterial eradication rate with the administration of antibiotic regimens recommended by international guidelines is not yet clear.

AIMS

To determine the eradication frequency of H. pylori infection in the adult Mexican population that underwent treatment with the conventional triple regimen.

MATERIAL AND METHODS

A cross-sectional study was carried out that evaluated the effectiveness of the triple regimen in individuals with confirmed infection that received consensual treatment and then underwent tests to corroborate eradication.

RESULTS

From a total of 249 potential case records, 26 did not meet the inclusion criteria. Two hundred and twenty-three patients were enrolled for analysis, 64,00% women and 36,00% men, with a mean age of 49,4 years (range 17-86). Comorbidities presented in 55,60% of the patients and 28,60% referred to chronic use of nonsteroidal anti-inflammatory drugs (NSAIDs). Bacterial eradication with the triple regimen was 65,50% (146/223); of the 77 patients with no eradication, 11 received a quadruple regimen as second-line treatment resulting in bacterial eradication in 5/11 (45,45%) patients, for an overall eradication of 67,70%.

CONCLUSIONS

The eradication rate in our study population was suboptimal due to the probability of multiple factors that are difficult to identify, given the retrospective design of the study. A prospective and controlled evaluation of the recommended regimens needs to be carried out in order to determine their true effectiveness.

Helicobacter pylori therapy: Present and future

Helicobacter pylori (H. pylori) plays a crucial role in the pathogenesis of chronic active gastritis, peptic ulcer and gastric mucosa-associated lymphoid tissue-lymphoma, and is also involved in carcinogenesis of the stomach. H. pylori treatment still remains a challenge for physicians, since no current first-line therapy is able to cure the infection in all treated patients. Several factors may help in the eradication of therapy failure. We reviewed both bacterial and host factors involved in therapeutic management of the H. pylori infection. In addition, we evaluated data on the most successful therapy regimens - sequential and concomitant therapies - currently available for H. pylori eradication.