An improvement in isolation and preservation of clinical strains of Helicobacter pylori.
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Date
2011-01
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Abstract
Background and Aim: Isolation of H. pylori from gastric mucosal biopsy specimens is a
prerequisite for further studies addressing drug susceptibility testing, analysis and
characterization of virulence factors, molecular epidemiology studying or other comparative
studies. In this study, we used a modified enriched culture medium with short incubation time
to improve the isolation rate of H. pylori from the clinical specimens.
Methods: Between October 2008 and October 2009, 266 dyspeptic patients attending the
endoscopy ward of Motahhary Clinic of Shiraz University of Medical Sciences, were
investigated. The biopsy samples were cultured on two selective media called M1, which we
used in our previous studies, and a modified medium called M2. The cultures were kept in a
microaerophilic atmosphere at 37 °C. The plates were inspected first on day 1, and then on
daily basis for a total of 10 days. The isolates were confirmed as H. pylori by colony
morphology and positive oxidase, catalase and rapid urease tests. We used the same media
and culture conditions to subculture the isolates for several times. Specimens were considered
to be H. pylori positive if either the culture or two of the three diagnostic methods yielded
positive results. .
Results: The isolation rate of H. pylori strains from the samples was significantly higher on
M2 in comparison with M1 medium (p<0.05). The bacterial growth on M2 was observed after
a significantly shorter time (p<0.05), i.e., after incubation for about 24 hrs. Following these
procedures, the preservation time could be extended beyond 6 months without a significant
loss of viability.
Conclusion: The modified culture technique enabled a shorter incubation time and a higher isolation rate for H.pylori obtained from clinical samples .
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Keywords
Culture, diagnosis, Helicobacter pylori, isolation, preservation
Citation
Farshad Shohreh, Japoni Aziz, Shahidi Maneli Amin, Hosseini Marziyeh, Alborzi Abdolvahab. An improvement in isolation and preservation of clinical strains of Helicobacter pylori. Tropical Gastroenterology. 2011 Jan-Mar; 32(1): 36-40.