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Article

Secondary Antibiotic Resistance, Correlation between Genotypic and Phenotypic Methods and Treatment in Helicobacter pylori Infected Patients: A Retrospective Study

1
Department of Public Health and Infectious Diseases, Sapienza University, 00185 Rome, Italy
2
Department of Translational and Precision Medicine, Sapienza University, 00185 Rome, Italy
*
Author to whom correspondence should be addressed.
Antibiotics 2020, 9(9), 549; https://doi.org/10.3390/antibiotics9090549
Received: 7 July 2020 / Revised: 17 August 2020 / Accepted: 25 August 2020 / Published: 28 August 2020
(This article belongs to the Section Mechanism and Evolution of Antibiotic Resistance)
The aim of this study was to evaluate the secondary resistance in Helicobacter pylori (Hp) infected patients who had failed a first-line therapy, and to compare the genotypic tests performed directly on gastric samples with phenotypic tests performed on culture media. The eradication rate of patients treated with bismuth quadruple therapy (BQT) is also evaluated. A total of 80 positive specimens were retrospectively examined. Antibiotic susceptibility testing of Hp strains was performed by E-test, whereas a molecular commercially available method was used for detecting the mutations involved in clarithromycin and levofloxacin resistance. High resistance levels to metronidazole and clarithromycin (61.6% and 35%, respectively) and worrying resistance levels to levofloxacin (15%) were found phenotypically. Multiple resistance to two or three antibiotics was observed as well. The polymorphism A2143G on clarithromycin 23S rRNA gene was found in 34/80 (42.5%) isolates including 10 mixed infections (29%), whereas 28/80 (35%) strains were resistant phenotypically. Levofloxacin resistance corresponded to 30% by PCR and 15% by E-test (statistically significant, p < 0.05). The knowledge of clarithromycin and levofloxacin resistance is crucial to establish an appropriate therapy in different geographical areas. The genetic methods were superior to phenotypic techniques in the absence of live bacteria or for identifying mixed infections that may lead to a resistance underestimation. The BQT eradication rate was effective (90%). View Full-Text
Keywords: Helicobacter pylori infection; molecular methods; E-test; multiresistance; patients therapy Helicobacter pylori infection; molecular methods; E-test; multiresistance; patients therapy
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MDPI and ACS Style

Mascellino, M.T.; Oliva, A.; Miele, M.C.; De Angelis, M.; Bruno, G.; Severi, C. Secondary Antibiotic Resistance, Correlation between Genotypic and Phenotypic Methods and Treatment in Helicobacter pylori Infected Patients: A Retrospective Study. Antibiotics 2020, 9, 549. https://doi.org/10.3390/antibiotics9090549

AMA Style

Mascellino MT, Oliva A, Miele MC, De Angelis M, Bruno G, Severi C. Secondary Antibiotic Resistance, Correlation between Genotypic and Phenotypic Methods and Treatment in Helicobacter pylori Infected Patients: A Retrospective Study. Antibiotics. 2020; 9(9):549. https://doi.org/10.3390/antibiotics9090549

Chicago/Turabian Style

Mascellino, Maria T., Alessandra Oliva, Maria C. Miele, Massimiliano De Angelis, Giovanni Bruno, and Carola Severi. 2020. "Secondary Antibiotic Resistance, Correlation between Genotypic and Phenotypic Methods and Treatment in Helicobacter pylori Infected Patients: A Retrospective Study" Antibiotics 9, no. 9: 549. https://doi.org/10.3390/antibiotics9090549

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