Publications (23)53.96 Total impact
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Article: Living in Sofia is associated with a risk for antibiotic resistance in Helicobacter pylori: a Bulgarian study.
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ABSTRACT: The aim of the retrospective study was to evaluate geographic regions and residence places as possible risk factors for primary Helicobacter pylori antibiotic resistance in Bulgaria. Data from Sofia region, exhibiting the highest living density, were compared to those from other residence places. In total, 588 H. pylori strains from untreated adults who filled a questionnaire were evaluated. Strain susceptibility was assessed by a breakpoint susceptibility test. Resistance rates to metronidazole and clarithromycin have been found to increase, and that to tetracycline has been found to decrease over years. Clarithromycin resistance was 1.7-fold higher in Sofia inhabitants (23.5 %) than elsewhere (13.8 %) and 4.7-fold higher than that in villages (5.0 %). Moreover, the clarithromycin resistance rate was 2.6-fold lower in northern region (8.2 %) than in southern region (21.7 %). On multivariate analysis, sex and residence place were independent predictors for metronidazole resistance. Men were at lower risk for metronidazole resistance compared with women [odds ratio (OR) 0.703; 95 % confidence interval (CI) 0.499-0.990]. Importantly, Sofia inhabitants were at higher risk for the resistance compared with those living elsewhere (OR 1.453; 95 % CI 1.009-2.093). In conclusion, living in Sofia was associated with a risk for antibiotic resistance in H. pylori-positive adults. Living density could be associated with H. pylori resistance rates.Folia Microbiologica 04/2013; · 0.68 Impact Factor -
Article: Significance of Helicobacter pylori vacA intermediate region genotyping-a Bulgarian study.
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ABSTRACT: The significance of the intermediate (i) region of the Helicobacter pylori vacA gene as a virulence factor associated with the severity of gastric disease is still disputable. The aim of the present study was to evaluate the prevalence and significance of vacA i alleles alone or in combination with other vacA alleles in symptomatic Bulgarian patients and to find out possible associations between vacA i genotype and patients' disease, age, sex, and other H. pylori virulence factors. Unlike vacA s1 and m1, vacA i1 prevalence was significantly higher (75.0%) in strains from peptic ulcer patients than in strains from nonulcer patients with gastric diseases (58.6%) (P = 0.022). Less virulent vacA s1 i2 m2 strains were more prevalent in females (P = 0.03), and cagA(+) was associated with vacA i1, s1, m1, and their combinations. In conclusion, vacA i status is a better predictor for the strain virulence than other vacA alleles.Diagnostic microbiology and infectious disease 08/2012; 74(3):253-7. · 2.45 Impact Factor -
Article: High prevalence and resistance rates to antibiotics in anaerobic bacteria in specimens from patients with chronic balanitis.
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ABSTRACT: Aim of the study was to assess both prevalence and antibiotic resistance in anaerobic bacteria from glans penis skin of 70 adults. Strain susceptibility was determined by breakpoint susceptibility test or E test. In 9 asymptomatic, 48 untreated and 13 treated symptomatic patients, anaerobes were found in 22.2%, 70.8% and 53.3%, respectively. Gram-positive strains (GPAs) were 2.2-fold more common than Gram-negative ones. Prevalent Gram-negative (GNAs) and GPAs were Prevotella spp. and anaerobic cocci, respectively. Clostridium difficile strain was found in an untreated patient. In GNAs, resistance rates to amoxicillin, metronidazole, clindamycin, tetracycline, levofloxacin, and amoxicillin/clavulanate were 42.1, 0, 52.6, 53.3, 86.7 and 5.2%, respectively. In GPAs, the resistance rates to metronidazole, clindamycin, tetracycline, levofloxacin and amoxicillin/clavulanate were 18.2, 34.1, 52.6, 36.8 and 0%, respectively. In conclusion, anaerobes were 1.6-fold more frequent in untreated symptomatic patients compared with other patients, suggesting their participation in development of chronic balanitis. GPAs were more common than GNAs. The resistance rates to amoxicillin, clindamycin, tetracycline, and levofloxacin were high. Most active agents were metronidazole and amoxicillin/clavulanate. Resistance in anaerobes varies according to sites of specimens and years of study.Anaerobe 06/2012; 18(4):414-6. · 2.41 Impact Factor -
Article: Benefits of Helicobacter pyloricagE genotyping in addition to cagA genotyping: a Bulgarian study
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ABSTRACT: Associations of Helicobacter pylori cagE status with complex patient characteristics remain to be elucidated in Eastern Europe. The aim of this study was to assess the frequencies of cagE gene and cagA/cagE combinations in H.pylori strains from symptomatic Bulgarian patients and to improve cagA detection. cagA and cagE genotypes were evaluated in 219 patients with single-strain infections. In total, 84.9% of strains were cagA +, while 68.5% were cagE +. cagA +, cagE +, and cagA +/cagE + strains were more prevalent in peptic ulcer (93.8%, 84.4%, and 84.4%) compared with nonulcer patients (81.3%, 61.9%, and 61.3%, respectively). In elderly patients, cagE + and cagA +/cagE + strains were 1.9-fold more common than in the 12 children evaluated. Only 10% of the elderly subjects harbored low-virulence cagA +/cagE − strains compared with 16.8% of adults and 41.7% of children. Intriguingly, prevalence of the cagA +/cagE − genotype was 2.1-fold lower in men than in women, suggesting a higher frequency of more virulent strains in men. The presence of both cag genes and combinations was not linked to strain susceptibility to clarithromycin or metronidazole, place of residence, or prior therapy. Use of an extra primer pair increased cagA detection in 14.7% of 31 cagA − strains. In conclusion, use of a second primer pair for the cagA gene can be recommended in countries with common cagA + strains. Although both cag genes were linked to severe diseases in Bulgarian patients, the best discrimination of virulent strains was obtained by the cagA/cagE combination or by the cagE gene alone. cagE prevalence increased gradually with patient age, while the cagA +/cagE − genotype, implying a disrupted cag pathogenicity island, was associated with both younger age and female gender. Keywords H.pylori –Prevalence–Genotype– cagA – cagE –Resistance–Ulcer–Gastritis–Age–Sex–GenderAntonie van Leeuwenhoek 04/2012; 100(4):529-535. · 2.09 Impact Factor -
Article: Helicobacter pylori oipA genetic diversity and its associations with both disease and cagA, vacA s, m, and i alleles among Bulgarian patients.
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ABSTRACT: Prevalence of outer inflammatory protein (oipA) gene functional status in Helicobacter pylori strains from Southeastern Europe is still unclear. H. pylori strains from 70 symptomatic patients were polymerase chain reaction (PCR) assessed for cagA and vacA types, and oipA gene functional status was evaluated by PCR and sequencing. Our results demonstrated a high prevalence of strains with oipA status "on" genes (81%) and strong association between them and peptic ulcers, cagA, and vacA s1 and s1/m1 genotypes, regardless of the patient gender, place of residence, and age. Importantly, most vacA i1 strains (93%) harbored oipA status "on" versus only 57% of those with vacA i2 type. The vacA i1 genotype was less frequent (66%) than both cagA and vacA s1 types. The virulent strains with cagA(+) and vacA s1, m1, and i1 were detected in 35% as a predominant genotype and almost all (96%) of these strains harbored oipA status "on". In conclusion, the high prevalence of in-frame oipA gene strains (81%), associated with peptic ulcers and cagA(+), vacA s1, m1, m2, and, importantly, i1 genotypes, indicates a strong synergistic activity of H. pylori virulence factors.Diagnostic microbiology and infectious disease 09/2011; 71(4):335-40. · 2.45 Impact Factor -
Article: Numerous risk factors for Helicobacter pylori antibiotic resistance revealed by extended anamnesis: a Bulgarian study.
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ABSTRACT: The aim of this study was to assess risk factors for primary Helicobacter pylori antibiotic resistance by an extended anamnesis. In total, 519 H. pylori strains from untreated symptomatic adults who answered a questionnaire were evaluated. Strain susceptibility was assessed by a breakpoint susceptibility test. Primary resistance rates were 29.5 % for metronidazole, 17.9 % for clarithromycin, 7.3 % for metronidazole+clarithromycin, 4.0 % for tetracycline and 10.8 % for ciprofloxacin. On multivariate analysis, younger (≤65 years) age was an independent predictor for metronidazole resistance. To our knowledge, for the first time, being a member of the health-care profession was revealed as a risk factor for H. pylori resistance to metronidazole and both metronidazole and clarithromycin. Respiratory and urinary tract infections were independent predictors of clarithromycin and ciprofloxacin resistance, respectively. The presence of co-infections was an independent risk factor for clarithromycin, metronidazole and ciprofloxacin resistance. Surprisingly, female sex was the only predictor for tetracycline resistance. The antibiotic resistance rates were not associated with disease type, place of residence, birthplace, educational level, non-steroidal anti-inflammatory drug or proton pump inhibitor use, smoking or dietary factors, such as consumption of coffee, yogurt, green tea, raw garlic, raw onion, honey or meat. There was a trend for higher metronidazole resistance in strains from diabetic patients. In conclusion, the extended anamnesis of H. pylori-positive patients should include data on patient age, sex, whether they are in the health-care profession, co-infections and possibly diabetes to improve the choice of empiric therapy. Tailored treatment based on the extended anamnesis is suggested, and susceptibility testing of the strains is recommended for patients at risk for antibiotic resistance, especially to clarithromycin, fluoroquinolones or both metronidazole and clarithromycin.Journal of Medical Microbiology 08/2011; 61(Pt 1):85-93. · 2.50 Impact Factor -
Article: Benefits of Helicobacter pylori cagE genotyping in addition to cagA genotyping: a Bulgarian study.
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ABSTRACT: Associations of Helicobacter pylori cagE status with complex patient characteristics remain to be elucidated in Eastern Europe. The aim of this study was to assess the frequencies of cagE gene and cagA/cagE combinations in H. pylori strains from symptomatic Bulgarian patients and to improve cagA detection. cagA and cagE genotypes were evaluated in 219 patients with single-strain infections. In total, 84.9% of strains were cagA (+), while 68.5% were cagE (+). cagA (+), cagE (+), and cagA (+)/cagE (+) strains were more prevalent in peptic ulcer (93.8%, 84.4%, and 84.4%) compared with nonulcer patients (81.3%, 61.9%, and 61.3%, respectively). In elderly patients, cagE (+) and cagA (+)/cagE (+) strains were 1.9-fold more common than in the 12 children evaluated. Only 10% of the elderly subjects harbored low-virulence cagA (+)/cagE (-) strains compared with 16.8% of adults and 41.7% of children. Intriguingly, prevalence of the cagA (+)/cagE (-) genotype was 2.1-fold lower in men than in women, suggesting a higher frequency of more virulent strains in men. The presence of both cag genes and combinations was not linked to strain susceptibility to clarithromycin or metronidazole, place of residence, or prior therapy. Use of an extra primer pair increased cagA detection in 14.7% of 31 cagA (-) strains. In conclusion, use of a second primer pair for the cagA gene can be recommended in countries with common cagA (+) strains. Although both cag genes were linked to severe diseases in Bulgarian patients, the best discrimination of virulent strains was obtained by the cagA/cagE combination or by the cagE gene alone. cagE prevalence increased gradually with patient age, while the cagA (+)/cagE (-) genotype, implying a disrupted cag pathogenicity island, was associated with both younger age and female gender.Antonie van Leeuwenhoek 06/2011; 100(4):529-35. · 2.09 Impact Factor -
Article: Trends in antibiotic resistance in Prevotella species from patients of the University Hospital of Maxillofacial Surgery, Sofia, Bulgaria, in 2003-2009.
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ABSTRACT: Head-and-neck infections often involve anaerobes such as Prevotella species. Aim of the present study was to assess the evolution and the factors associated with resistance in Prevotella species to penicillin, clindamycin, metronidazole, tetracycline and β-lactams/β-lactamase inhibitors (BL/BLIs). In total, 192 Prevotella strains, isolated from patients with oral and head-and-neck infections, were evaluated. Common isolates were Prevotella intermedia and Prevotella melaninogenica within the pigmented species as well as Prevotella oris and Prevotella oralis group within the non-pigmented species. Overall resistance was 43.2% for penicillin, 10.9% for clindamycin, 0% for metronidazole. Nonsusceptibility to tetracycline was 29.1% without significant differences in resistance rates between pigmented and other species. Penicillin resistant strains were β-lactamase positive. From 2003-2004 to 2007-2009, penicillin resistance rates increased about four-fold (from 15.4% to 60.6%). Clindamycin resistance did not show evolution, whereas tetracycline nonsusceptibility decreased from 43.3% in 2003-2004 to 20.7% in 2007-2009. Except for one (0.5%) P. oralis strain with intermediate susceptibility to BL/BLIs, the other strains were susceptible to the agents. In conclusion, in Prevotella strains from patients with head-and-neck infections, the resistance rate to penicillin increased, that to clindamycin remained stable and the nonsusceptibility rate to tetracycline decreased during the period. Activity against >99% of Prevotella strains was observed with metronidazole and BL/BLIs. The penicillin resistance and tetracycline nonsusceptibility were associated with the year of study, national antibiotic consumption and possibly with previous treatment (for tetracycline). The evolution of penicillin resistance in Prevotella strains was highly dynamic.Anaerobe 10/2010; 16(5):489-92. · 2.41 Impact Factor -
Article: Two-decade trends in primary Helicobacter pylori resistance to antibiotics in Bulgaria.
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ABSTRACT: Evaluating long-term trends in antibiotic resistance can predict earlier the short-term changes in resistance patterns. The aim of the present study was to compare primary resistance rates in 501 Helicobacter pylori strains in 2007 to 2009 to those in 1990 to 1995 (179 strains) and the antibiotic MICs to detect the 20-year resistance evolution. In 2007 to 2009, strains from children exhibited lower resistance rates to metronidazole (16.4%) and ciprofloxacin (2.7%) than those from adults (27.3% and 10.3%, respectively). In 2008 to 2009, more children (29.3%) harbored clarithromycin-resistant strains compared to the adults (17.4%). Overall clarithromycin resistance rate (19.4%) in 2007 to 2009 was much higher than that in 1990 to 1995 (6.2%). MIC(90) of erythromycin in 1990 to 1995 was 142.2-fold lower than that of clarithromycin in 2007 to 2009. Clarithromycin MIC(90) increased >42-fold since 2001 to 2004. Quinolone resistance rate increased 7.7-fold, being 9.2% in 2007 to 2009 versus 1.2% in 1990 to 1995, with a 5-fold increase in MIC(90). Conversely, the amoxicillin resistance decreased from 3.2% in 1996 to 1999 to 0.4% in 2007 to 2009. The MIC(90)'s of tetracycline remained stable but MIC(50)'s of both metronidazole and tetracycline before 1996 decreased about 4-fold to 2007 to 2009. In conclusion, associations between the resistance evolution and patients' age groups as well as the national outpatient antibiotic use have been found. H. pylori resistance to antibiotics showed many long-term changes, with a more rapid evolution for clarithromycin than for the other antibiotics. Metronidazole and tetracycline did not show a resistance evolution but exhibited a decrease in MIC(50) since 1990. The significant increase in ciprofloxacin resistance was found only by extending the study period to 20 years.Diagnostic microbiology and infectious disease 08/2010; 67(4):319-26. · 2.45 Impact Factor -
Article: Association of iceA and babA genotypes in Helicobacter pylori strains with patient and strain characteristics.
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ABSTRACT: Data on the geographic prevalence of Helicobacter pylori iceA and babA alleles in Eastern Europe are still relatively scant. The aim of this study was to evaluate the prevalence of iceA and babA genotypes in Bulgarian symptomatic patients. The iceA and babA genotypes were evaluated by PCR with pure cultures in strains from 196 and 181 patients, respectively. Mixed infections were found in 10.2% of all 196 patients. Prevalence of H. pylori genotypes in patients with single-strain infections was 69.3% for iceA1, 30.7% for iceA2, 82.4% for cagA(+), 89.2% for vacA s1, 10.8% for vacA s2, 39.8% for vacA m1, 60.2% for vacA m2 and 48.8% for babA2. Within the iceA1 positive strains, 94.3% and 88.5% were also vacA s1a and cagA positive, respectively. Of the babA2 positive strains, 100.0%, 92.4% and 72.2% were also vacA s1a, cagA and iceA1 positive, respectively. Ulcer patients had more often strains with cagA positive status and vacA s1a allele. Although neither iceA1 nor babA2 were more common in ulcer patients, the combination of both alleles was more frequent (48.1%) in the ulcer patients than in the rest (28.7%). Clarithromycin susceptible strains had more often iceA1 allele (74.4%) than the resistant strains (55.3%). In conclusion, the results demonstrated a high prevalence of virulent H. pylori in Bulgaria. Both iceA1 and babA2 genotypes were associated with other virulence factors of H. pylori and, in addition, the iceA1 allele was associated with the strain susceptibility.Antonie van Leeuwenhoek 05/2010; 98(3):343-50. · 2.09 Impact Factor -
Article: High prevalence of virulent Helicobacter pylori strains in symptomatic Bulgarian patients.
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ABSTRACT: The aim of the study was to evaluate the prevalence of main virulence genes in Helicobacter pylori strains from 116 patients with peptic ulcers (41 cases) and nonulcer diseases (75) by polymerase chain reaction (PCR) with pure cultures and to compare the results with those by multiplex PCR in 39 H. pylori-positive gastric biopsies in another center in Sofia, Bulgaria. Strain susceptibility to amoxicillin, metronidazole, and clarithromycin was determined by agar dilution method. By PCR with pure cultures, coinfections with multiple H. pylori strains were found in 8 (6.9%) patients who were excluded from the statistical analysis. Prevalence of toxigenic type vacA s1 was higher (91.7%) than that usually reported in Europe. cagA-positive genotype was detected in most (81.5%) strains, and almost all of them harbored vacA s1 genotype. Strains with cagA+/vacA s1a genotype were more common (80.6%) than the other genotypes (19.4%, P = 0.0001). The ulcer patients had more often virulent strains than the other patients (92.3% versus 75.4% for cagA+, 100.0% versus 87.0% for vacA s1, 100% versus 84.0% for vacA s1a, and 92.3% versus 73.9% for cagA+/vacA s1a, respectively). The prevalence of H. pylori virulence-associated genes was not associated with patients' sex and age or with the antibacterial resistance of strains. The most common H. pylori genotype was cagA+/vacA s1a. Similar prevalence of cagA-positive (82.1%), vacA s1 (97.4%), and cagA+/vacA s1 strains (79.5%) was found by multiplex PCR in gastric biopsies in the 2nd center. In conclusion, H. pylori strains with virulent genotypes are widespread in symptomatic Bulgarian patients.Diagnostic microbiology and infectious disease 09/2009; 64(4):374-80. · 2.45 Impact Factor -
Article: Evaluation of clinical and socio-demographic risk factors for antibacterial resistance of Helicobacter pylori in Bulgaria.
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ABSTRACT: The aim of this study was to assess the clinical and socio-demographic risk factors for primary Helicobacter pylori antibacterial resistance. In total, 266 consecutive H. pylori strains, from untreated symptomatic adult patients who answered a questionnaire, were evaluated. Strain susceptibility to amoxicillin, metronidazole, clarithromycin and tetracycline was tested by a breakpoint susceptibility test. Metronidazole resistance was found in fewer (17.0 %) peptic ulcer patients than in non-ulcer subjects (28.3 %, P=0.037), as well as in fewer patients born in villages (12.7 %) than in those born in towns (27.6 %, P=0.016). Clarithromycin resistance varied from 8.8 to 23.4 % (P=0.009) within the hospital centres. The highest clarithromycin resistance rate was found in hospital centre A (23.4 %) compared to other centres (12.9 %, P=0.041). The factors sex, age, symptom duration, non-steroidal anti-inflammatory drug use, diabetes, type of profession and educational level were not associated with H. pylori resistance. Logistic regression revealed that the risk factors for metronidazole resistance were non-ulcer disease [odds ratio (OR) 1.95, 95 % confidence interval (95 % CI) 1.04-3.65] and a birthplace of a town (OR 2.64, 95 % CI 1.18-5.93). The hospital centre may be a risk factor (OR 2.07, 95 % CI 1.02-4.21) for clarithromycin resistance but further studies are required to verify this suggestion. In conclusion, the knowledge of the risk factors for H. pylori resistance to antibacterials could facilitate the treatment choice for H. pylori eradication.Journal of Medical Microbiology 02/2009; 58(Pt 1):94-100. · 2.50 Impact Factor -
Article: Prevalence and evolution of Helicobacter pylori resistance to 6 antibacterial agents over 12 years and correlation between susceptibility testing methods.
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ABSTRACT: The aim of this study was to evaluate Helicobacter pylori antibacterial resistance in 2005 to 2007, resistance evolution since 1996 to 1999, and performance of breakpoint susceptibility testing (BST) compared with E test for clarithromycin or agar dilution method (ADM) for metronidazole, amoxicillin, tetracycline, and ciprofloxacin. Resistance in 613 untreated adults, 91 treated adults, and 75 untreated children was 25%, 48.4%, and 16% for metronidazole; 17.8%, 45.1%, and 18.7% for clarithromycin; 4.4%, 13.3%, and 2.7% for tetracycline; and 7.7%, 18.2%, and 6.8% for ciprofloxacin, respectively. Resistance to amoxicillin (0.9%) and nitrofurantoin (1.3%) was uncommon. Three strains (0.4%) exhibited triple resistance to amoxicillin, metronidazole, and clarithromycin. Primary resistance rates in adults and children were comparable. Metronidazole resistance was less common in ulcer adults than in the rest. Primary clarithromycin resistance increased significantly from 10% in 1996 to 1999 to 17.9% in 2005 to 2007. Many strains (26.4%) from treated adults showed resistance to metronidazole and clarithromycin. Category agreement between the BST and E test or ADM results was good (93.3-100%). In conclusion, the increasing clarithromycin resistance and presence of multidrug resistance are worrying. Fluoroquinolones should be used with caution for H. pylori eradication in treated patients.Diagnostic Microbiology and Infectious Disease 05/2008; 60(4):409-15. · 2.53 Impact Factor -
Article: Helicobacter pylori and Helicobacter heilmannii in untreated Bulgarian children over a period of 10 years.
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ABSTRACT: The aims of the study were to evaluate the incidence of Helicobacter pylori and Helicobacter heilmannii in untreated Bulgarian children from 1996 to 2006, to analyse the performance of diagnostic tests, and to look at H. pylori density in specimens by culture. Antral specimens from children with chronic gastritis (n=513), peptic ulcers (n=54) and other diseases (n=91) were evaluated by direct Gram staining (DGS), in-house rapid urease test (RUT) and culture. The living environment and semi-quantitative H. pylori density were assessed in 188 and 328 children, respectively. H. pylori infection was found in children with ulcers (77.8 %), chronic gastritis (64.5 %) and other diseases (36.3 %). Half (51.4 %) of patients aged 1-5 years and 77.4 % of those aged 16-17 years were H. pylori-positive. Of all children, 328 (49.8 %) showed positive DGS, 184 (28 %) had a positive RUT, and 386 (58.7 %) were culture-positive. Unlike gastric mucus specimens, frozen biopsy specimens provided reliable diagnosis. H. heilmannii was observed in two (0.3 %) children. High H. pylori density (growth into all quadrants of plates) was found in 18 % of 328 children evaluated, involving 31 % of ulcer and 16.7 % of non-ulcer patients. H. pylori infection was more common in rural children with chronic gastritis (91.3 %) than in the remainder (66.7 %). In conclusion, H. pylori infection was common in symptomatic Bulgarian children. The infection prevalence was >77 % in patients aged 16-17 years, in children with a duodenal ulcer, and in rural patients. H. heilmannii infection was uncommon. The performance of the bacterial culture was good. The impact of H. pylori density on the clinical expression and eradication of the infection requires further evaluation. The results highlight the need for routine H. pylori diagnosis in rural children with chronic gastritis.Journal of Medical Microbiology 09/2007; 56(Pt 8):1081-5. · 2.50 Impact Factor -
Article: Anaerobic bacteria in 118 patients with deep-space head and neck infections from the University Hospital of Maxillofacial Surgery, Sofia, Bulgaria.
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ABSTRACT: The aim of this study was to assess the incidence and susceptibility to antibacterial agents of anaerobic strains in 118 patients with head and neck abscesses (31) and cellulitis (87). Odontogenic infection was the most common identified source, occurring in 73 (77.7%) of 94 patients. The incidence of anaerobes in abscesses and cellulitis was 71 and 75.9%, respectively, and that in patients before (31 patients) and after (87) the start of empirical treatment was 80.6 and 72.4%, respectively. The detection rates of anaerobes in patients with odontogenic and other sources of infection were 82.2 and 71.4%, respectively. In total, 174 anaerobic strains were found. The predominant bacteria were Prevotella (49 strains), Fusobacterium species (22), Actinomyces spp. (21), anaerobic cocci (20) and Eubacterium spp. (18). Bacteroides fragilis strains were isolated from 7 (5.9%) specimens. The detection rate of Fusobacterium strains from non-treated patients (32.2%) was higher than that from treated patients (13.8%). Resistance rates to clindamycin and metronidazole of Gram-negative anaerobes were 5.4 and 2.5%, respectively, and those of Gram-positive species were 4.5 and 58.3%, respectively. One Prevotella strain was intermediately susceptible to ampicillin/sulbactam. In conclusion, the start of empirical treatment could influence the frequency or rate of isolation of Fusobacterium species. The involvement of the Bacteroides fragilis group in some head and neck infections should be considered.Journal of Medical Microbiology 10/2006; 55(Pt 9):1285-9. · 2.50 Impact Factor -
Article: In vitro activity of Bulgarian propolis against 94 clinical isolates of anaerobic bacteria.
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ABSTRACT: The aim was to evaluate the effect of 30% ethanolic extract of Bulgarian propolis on 94 clinical anaerobic strains. The strains were tested by both agar-well diffusion (wells, 7 mm diameter) and disk-diffusion methods. Only 15% of Clostridium-, 3.3% of other Gram-positive- and 9.1% of Gram-negative anaerobic strains were not inhibited by 30 microL propolis extract per well. Propolis extract was more active than the ethanol (P < 0.001). By 30 microL extract per well, mean inhibitory diameters of the clostridia, other Gram-positive- and Gram-negative anaerobes were 11.5, 13.1, and 11.3 mm, and those by 90 microL were 16, 18.1 and 15.4 mm, respectively. Mean inhibitory diameters of all strains by 30 and 90 microL ethanol were only 8.4 and 9.5 mm. By 30 microL propolis extract per well, inhibitory diameters of 15 mm or more were more common in Gram-positive (32%) than in Gram-negative bacteria (13.6%, P < 0.05). Moist propolis disks inhibited more strains (89.4%) than dried disks (68.1%, P < 0.001). Most (81.8%) Bacteroides fragilis group strains and 75% of clostridial strains were inhibited by moist EEP disks. CONCLUSION: Bulgarian propolis was active against most anaerobic strains of different genera. In addition to oral pathogens, an activity of propolis against Clostridium, Bacteroides and Propionibacterium species was observed. The results could motivate a higher medical interest and further trials for evaluating the use of bee glue for prophylaxis or treatment of some anaerobic infections such as oral, skin and wound diseases.Anaerobe 08/2006; 12(4):173-7. · 2.41 Impact Factor -
Article: Antibacterial resistance in Helicobacter pylori strains isolated from Bulgarian children and adult patients over 9 years.
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ABSTRACT: The aim of this study was to evaluate the primary, combined and post-treatment antibacterial resistance rates in 1205 Helicobacter pylori strains from non-treated (786 adults, 282 children) and treated (109 adults, 28 children) patients in Bulgaria. Susceptibility was tested by the limited agar dilution method. Overall primary resistance rates to metronidazole, clarithromycin, amoxicillin, tetracycline and both metronidazole and clarithromycin were respectively 15.0, 12.5, 1.5, 3.4 and 4.7% in children and 25.6, 12.6, 0.8, 5.2 and 4.9% in adults. Primary metronidazole resistance in adults was more common than in children, but the differences for other agents tested were not significant. Primary resistance rates were in the range of those reported worldwide. There was no significant increase in primary resistance rates from 1996/1999 to 2003/2004; however, clarithromycin resistance rates exhibited a slight tendency to increase. Post-treatment resistance to amoxicillin was detected in 1.6% of 63 strains. Post-treatment resistance to metronidazole was common (81.6%) and that to clarithromycin was considerable (36%). Alarming emergence of strains with triple resistance to amoxicillin, metronidazole and clarithromycin was found in two non-treated and three treated patients. The results motivate a larger and continuing surveillance of H. pylori resistance in Bulgaria and worldwide.Journal of Medical Microbiology 02/2006; 55(Pt 1):65-8. · 2.50 Impact Factor -
Article: Activity of Bulgarian propolis against 94 Helicobacter pylori strains in vitro by agar-well diffusion, agar dilution and disc diffusion methods.
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ABSTRACT: Propolis exhibits antimicrobial, anti-inflammatory and other biological effects. The aim of this study was to evaluate the activity of 30 % ethanolic extract of Bulgarian propolis against 94 Helicobacter pylori strains by three methods. By the agar-well diffusion method, only 13.8 % of the strains exhibited no inhibition by 30 microl propolis extract (containing 9 mg propolis) and all isolates were inhibited to some extent by 90 microl of the extract (27 mg propolis) per well. The mean diameters of growth inhibition by 30, 60 or 90 microl propolis extract or 30 microl 96 % ethanol per well were 16.8, 19.2, 27.5 and 8.3 mm, respectively. The propolis extract was more active than the ethanol (P < 0.001). With 90 microl propolis extract per well, 69.4 % of the strains exhibited large diameters of growth inhibition (> or =20 mm) versus 26.6 % with 30 mul per well (P < 0.001). With moist propolis discs, inhibition was detected in more strains (92.1 %) than with dried discs (78.2 %, P < 0.05), with mean inhibitory diameters of 18.7 and 13.8 mm, respectively. By the agar dilution method, 100 and 300 microg propolis ml(-1) inhibited the growth of 57.1 % and 76.2 %, respectively, of the 21 strains tested. In conclusion, Bulgarian propolis had a strong and dose-dependent activity against most of the H. pylori strains tested. Although the effect of propolis on H. pylori in vitro is promising, further microbiological, pharmacological and clinical trials are required.Journal of Medical Microbiology 05/2005; 54(Pt 5):481-3. · 2.50 Impact Factor -
Article: Anaerobic microbiology in 198 cases of pleural empyema: a Bulgarian study.
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ABSTRACT: The aim of the study was to evaluate the incidence of anaerobic bacteria in 198 patients with pleural empyema and the susceptibility of isolates to eight antibacterial agents. Isolates were identified by the Crystal anaerobes identification system, API System rapid ID 32 A and/or routine methods. Susceptibility was tested by Sceptor MIC system for anaerobic bacteria and limited agar dilution method. Anaerobic bacteria were found in 74.2% of the patients and included 247 strains within 21 genera. The predominant anaerobes were Gram-positive anaerobic cocci (52 isolates), Fusobacterium (51), microaerophilic streptococci (24), Prevotella (19) and Bacteroides species (11). Common species/groups were Fusobacterium nucleatum (in 27.2% of specimens yielding anaerobes), Micromonas micros (8.2%), Finegoldia magna (7.5%), Bacteroides fragilis group (6.8%), Peptostreptococcus anaerobius (6.1%) and F. necrophorum (5.4%). No resistance to chloramphenicol and ampicillin/sulbactam was detected. The susceptibility rates of Gram-negative anaerobic isolates to penicillin, cefoxitin, clindamycin, clarithromycin, metronidazole and tetracycline were 63.8%, 90.2%, 87.8%, 58.6%, 98.8% and 71%, and those of Gram-positive anaerobes were 79.2%, 100%, 84.3%, 68.4%, 41.9% and 75%, respectively. The wide diversity of isolated anaerobic genera and species and the susceptibility patterns of the isolates emphasize the role of the anaerobic microbiology in cases of pleural empyema.Anaerobe 11/2004; 10(5):261-7. · 2.41 Impact Factor -
Article: Risk factors for primary Helicobacter pylori resistance in Bulgarian children.
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ABSTRACT: Risk factors for primary Helicobacter pylori resistance in 186 children with gastroduodenal diseases (44 from villages/small towns and 130 from large towns/cities) in 2000-2003 were tested. Susceptibility was tested by a limited agar dilution method. Overall resistance rates to metronidazole, clarithromycin, tetracycline and both metronidazole and clarithromycin were 14.5, 11.9, 3.3 and 4.3 %, respectively. No amoxycillin resistance was observed. Tetracycline resistance was found in six children aged 7-18 years. Clarithromycin resistance was more common in children from small towns/villages (22.7 %) than in those from large towns/cities (8.5 %, P < 0.05). There were no significant differences (P > 0.05) in resistance rates between children from northern Bulgaria and those from southern regions. Resistance rates in duodenal ulcer patients and other children were, respectively, 10.5 and 15 % (P > 0.20) for metronidazole and 10.5 and 12 % (P > 0.20) for clarithromycin. No combined resistance to metronidazole and clarithromycin was found in 22 children aged 1-7 years and in 34 children living in northern Bulgaria. There were no significant associations of resistance with sex and age group (1-7- versus 8-18-year-old children) for all antibacterial agents tested. In conclusion, primary H. pylori resistance was absent (for metronidazole + clarithromycin) or low (4.5 % for clarithromycin) in children aged 1-7 years. Place of residence was associated with clarithromycin resistance rates.Journal of Medical Microbiology 09/2004; 53(Pt 9):911-4. · 2.50 Impact Factor
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2002–2013
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Medical University of Sofia
- Department of Microbiology
Sofia, Oblast Sofiya-Grad, Bulgaria
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