| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1Department of Microbiology, Medical University of Sofia, Sofia, Bulgaria 2Second Surgery Department of Alexander Hospital, Sofia, Bulgaria 3Department of Gastroenterology, University Hospital ‘St Ivan Rilski', Sofia, Bulgaria
Correspondence: Lyudmila Boyanova (lboyanova{at}hotmail.com)
Helicobacter pylori infection causes chronic gastritis that can trigger peptic ulcer disease and gastric malignancy (Marshall, 1994). The serious complications of peptic ulcers (bleeding or perforation) affect many elderly patients worldwide (Pilotto, 2001). Successful eradication of the infection results in ulcer healing (Adamek et al., 1998) and may prevent the progression of intestinal metaplasia in elderly patients (Pilotto & Malfertheiner, 2002); however, clinical interest in H. pylori infection in elderly people remains low (Pilotto & Salles, 2002). Furthermore, gastroduodenal diseases are associated with other diseases in many old patients. The aim of this study was to evaluate the prevalence of H. pylori infection and primary H. pylori resistance to antimicrobial agents in elderly Bulgarian patients with gastroduodenal diseases.
A total of 127 consecutive elderly patients (60–89 years) with gastroduodenal diseases between January 1996 and July 2003 were evaluated. All were admitted because of abdominal complaints, mostly consisting of epigastric pain and dyspepsia. No patient had been treated previously for H. pylori infection. The classification of diseases as chronic gastritis, erosive gastritis, duodenal ulcer, stomach ulcer and stomach cancer was based on endoscopic findings, histology and clinical signs (Table 1). Endoscopy was performed with an Olympus GIF P20 (biopsy forceps K19). Two stomach biopsy specimens per patient were taken at 3–5 cm from the pylorus. Specimens were transported in Stuart's transport medium (Merck) for less than 5 h. Susceptibility to antimicrobial agents of 92 H. pylori isolates was investigated.
|
A smear was prepared from one part of the specimens by scraping the biopsy on a slide. The smear was used for a modified Gram stain with carbol fuchsin as the counterstain. For the urease test, another part of the biopsy specimen was placed in urea (10 %) agar medium as described previously (Boyanova et al., 1996), incubated at 37 °C and observed for colour change after 30 min and 3 h. The remaining part of the biopsy specimen was homogenized in 0.1 ml sterile saline with sterile needles and inoculated onto blood agar [Columbia agar base (Oxoid) or Brucella agar base (Becton Dickinson)] containing 10 % defibrinated sheep blood and 1 % Isovitalex (Becton Dickinson), with or without H. pylori selective supplement, containing 10 µg vancomycin, 5 µg trimethoprim, 5 µg cefsulodin and 5 µg amphotericin B ml-1 [H. pylori selective supplement (Dent); Oxoid]. One selective and one non-selective medium plate were used for primary culture of biopsy specimens. Plates were incubated for 12 days in a microaerobic atmosphere. H. pylori was identified by Gram staining of suspect colonies, lack of aerobic growth on blood-agar plates and testing for the presence of urease, oxidase and catalase. Specimens were considered as H. pylori positive only if culture or two of the other three diagnostic methods gave positive results.
In the screening agar method (SAM), two drops (approx. 60 µl) of H. pylori suspensions, prepared in Mueller–Hinton broth (NCIPD) to obtain McFarland turbidity standard 3–4, were inoculated on a quarter of the surface of Mueller–Hinton blood-agar plates (NCIPD) containing 1 % Isovitalex and one of the following drug concentrations: 8, 16 or 32 µg metronidazole ml-1, 0.25, 0.5, 1 or 2 µg clarithromycin or azithromycin ml-1, 0.5, 1 or 2 µg amoxicillin ml-1, 1 µg ciprofloxacin ml-1 or 4 µg tetracycline ml-1. Antimicrobial agents were obtained from Sigma (amoxicillin, metronidazole and tetracycline), Abbott Laboratories (clarithromycin), Balkanpharma (azithromycin) and Bayer Pharma (ciprofloxacin). The plates were incubated microaerobically at 37 °C for 3 days. If H. pylori growth appeared on the plate, the isolate was considered to be resistant to the corresponding drug. Non-selective medium plates were used as a control of strain viability. Primary resistance rates of 92 strains from elderly patients with gastroduodenal diseases were compared with those of 423 isolates from adults aged 19–59 years.
Minimal inhibitory concentrations (MICs) of clarithromycin were determined for 48 strains from elderly patients and were compared with those of 70 isolates from adults aged 19–59 years. McFarland 3 suspensions were prepared in Mueller–Hinton broth and 0.5 ml volumes were used to flood Mueller–Hinton blood-agar plates containing 1 % Isovitalex without antibiotics. E test strips (AB Biodisk) were placed on the plates and they were incubated for 48–72 h under microaerobic conditions. The results were read according to the supplier's recommendations. The breakpoints used to define resistance by SAM and E test were: > 8 µg metronidazole ml-1, > 1 µg clarithromycin and azithromycin ml-1, > 0.5 µg amoxicillin ml-1, > 4 µg tetracycline ml-1 and > 1 µg ciprofloxacin ml-1 (Megraud et al., 1999; NCCLS, 2000). Metronidazole resistance was determined from SAM results only.
Differences between patients with susceptible and resistant strains were assessed by S2 test with Yates's correction.
Scant data are available concerning both the incidence of H. pylori infection and the susceptibility patterns of isolates from elderly patients with dyspeptic complaints (Parsons et al., 2001; Pilotto, 2001; Pilotto & Malfertheiner, 2002; Pilotto & Salles, 2002). In the present study, H. pylori infection was found in 103 (81.1 %) elderly patients with gastroduodenal diseases (Table 1). Culture failed to detect H. pylori in nine (8.7 %) of the specimens that were positive with other diagnostic tests, probably as a result of the increase in gastric atrophy (Pilotto & Salles, 2002) and intestinal metaplasia or previous treatment for other infections in the older age group. Nevertheless, H. pylori infection was found in > 78 % of Bulgarian elderly patients with chronic gastritis and in 90.3 % of those with peptic ulcers, unlike several other studies that have reported H. pylori prevalence in elderly patients with peptic ulcers as 50–78 % (Pilotto, 2001; Pilotto & Malfertheiner, 2002; Pilotto & Salles, 2002). There was no statistically significant difference between the prevalence of H. pylori infection in elderly patients aged 60–69 years and that in older patients (P > 0.20).
According to recent studies, better H. pylori eradication has been obtained in patients aged over 60 years (except for type 2 diabetic patients) than in younger patients (Broutet et al., 2003; Sargyn et al., 2003). In the present study, the resistance rates to metronidazole, tetracycline and newer macrolides in elderly patients were similar to those in younger adults (P > 0.20). Amoxicillin resistance was not detected in the elderly but was found in 1 % of strains isolated from younger adults (Table 2). Although ciprofloxacin is not currently used in treatment regimens for H. pylori eradication, a slightly higher prevalence of ciprofloxacin resistance was detected in older (8.9 %) than in younger adults (6.1 %) (P > 0.20). Elderly patients are at higher risk of hospitalization and treatment for respiratory or urinary infections (Pilotto & Salles, 2002). This could explain the rate of ciprofloxacin resistance in older patients.
|
According to several authors, the overall rate of metronidazole resistance has shown a tendency to decrease with age, whereas the prevalence of clarithromycin resistance has not been associated with age (Fraser et al., 1999; Parsons et al., 2001). In the present study, the MIC values of clarithromycin for strains from elderly patients were similar to those from younger adults. Although the prevalence of combined resistance to metronidazole and clarithromycin in the elderly (4.6 %) was similar to that in other adults (4.3 %), fewer (52.6 %) metronidazole-resistant strains from elderly patients had high levels of metronidazole resistance (MIC > 32 µg ml-1) than those from younger adults (78.7 %) (P < 0.001).
In conclusion, because H. pylori infection was detected in most elderly patients with gastroduodenal diseases and the primary resistance rates in the elderly patients were similar to those in younger adults, microbiological diagnostic tests for H. pylori infection in this poorly studied group of elderly patients with dyspeptic complaints are necessary and beneficial.
 |
References |
|---|
 TOP References |
|---|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| INT J SYST EVOL MICROBIOL | J MED MICROBIOL | MICROBIOLOGY | J GEN VIROL | ALL SGM JOURNALS |
