Rev Esp Quimioter. 1999 Dec;12(4):340-5.
[Relationship between antimicrobial susceptibility and virulence factors in Helicobacter pylori clinical isolates]

[Article in Spanish]

Damaso D, Alarcon T, Prieto N, Lopez-Brea M.

Servicio de Microbiologia, Hospital Universitario de la Princesa, Diego de Leon n(o) 62, 28006 Madrid.

The aim of this study was to determine the relationship between the antibiotic susceptibility and different virulence factors among Helicobacter pylori clinical isolates. One hundred and forty-five strains were isolated from biopsy cultures obtained from adult patients. Antimicrobial susceptibility to amoxicillin, clarithromycin, metronidazole and tetracycline were tested using an agar dilution method. cagA and iceA genes and s1 and s2 alleles of vacA were studied by polymerase chain reaction. A group of patients had been previously treated for H. pylori infection. We found a resistance rate of 28.7% and 16.5% to metronidazole and clarithromycin, respectively. We did not find any resistance to amoxicillin or tetracycline. The cagA gene and s1 allele were detected in 86.3% and 65.2% of the strains. One hundred and two (71.3%) strains were iceA+. cagA+ strains showed lower percentages of resistance to antibiotics, as did vacA s1 and iceA+ strains. The role of lower rates of resistance to clarithromycin and metronidazole in more virulent H. pylori strains may have favorable effects in their eradication in patients infected with these strains.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10855013&dopt=Abstract antibiotic amoxicillin




J Vet Med Sci. 2000 Oct;62(10):1053-7.
A 10-year survey of antimicrobial susceptibility of streptococcus suis isolates from swine in Japan.

Kataoka Y, Yoshida T, Sawada T.

Department of Veterinary Microbiology, Nippon Veterinary and Animal Science University, Musashino, Tokyo, Japan.

A number of 689 Streptococcus suis isolates collected nationwide from diseased and healthy pigs from 1987 to 1996 were surveyed for antibiotic susceptibilities to 11 drugs. No isolates resistant to amoxicillin, chloramphenicol, and sulfamethoxazole/trimethoprim were found. Isolates were highly susceptible to penicillins (penicillin G, ampicillin, and amoxicillin) except cloxacillin. They were not susceptible to tetracycline, streptomycin, and kanamaycin (MIC90 50 microg/ml, > or = 100 microg/ml, and > or = 100 microg/ml, respectively). Multiple-resistant isolates (> or = 3 antimicrobial agents) were found in 20.3% of all isolates tested.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11073075&dopt=Abstract antibiotic amoxicillin




Pediatr Infect Dis J. 2000 Dec;19(12):1167-71.
Helicobacter pylori culture and antimicrobial susceptibility from pediatric patients in Michigan.

Tolia V, Brown W, El-Baba M, Lin CH.

Division of Pediatric Gastroenterology, Children's Hospital of Michigan, Wayne State University School of Medicine, Detroit 48201, USA.

BACKGROUND: We recently observed a high failure rate in the eradication of Helicobacter pylori infection in children with 2-week triple therapy using lansoprazole, amoxicillin and clarithromycin. We performed a prospective evaluation of antral biopsies of all children subsequently diagnosed with H. pylori gastritis for culture and antimicrobial susceptibility assessment. METHODS: All children with antral nodularity and/or an elevated anti-H. pylori IgG titer underwent antral biopsies for histology, urease test and culture while undergoing an upper endoscopy for routine indications. All positive cultures were tested for antimicrobial susceptibility by E-test for clarithromycin, amoxicillin, tetracycline and metronidazole. RESULTS: Thirty-one children (16 male, 15 female) between 2 and 19 years of age were diagnosed with H. pylori gastritis by histology. However, culture was positive in only 22 of 31 (71%) patients. The E-test in vitro antimicrobial susceptibility testing revealed that 95.6% of the isolates were susceptible to amoxicillin, 59% to clarithromycin and 54.6% to metronidazole. There was no resistance to tetracycline. CONCLUSION: Evaluation of antibiotic resistance profiles from pediatric patients from different geographic areas can help in optimizing therapeutic regimen to prevent treatment failures. Metronidazole and clarithromycin resistance is much higher in our pediatric population than reported in adults and could be a major contributor to failure of H. pylori eradication.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11144378&dopt=Abstract antibiotic amoxicillin




Braz J Infect Dis. 1998 Feb;2(1):25-30.
Evaluation of the in vitro Activity of Cefprozil Relative to Other Oral Antimicrobial Agents Against Bacteria in Clinical Specimens from Patients in Sao Paulo With Respiratory Tract Infections.

Sader HS, Cereda R, Oplustil C, Mendes CM.

Division of Infectious and Parasitic Diseases, Federal University of Sao Paulo.

Cefprozil is a new oral second generation cephalosporin. Its in vitro antimicrobial activity was evaluated against 371 recent clinical isolates from patients with respiratory infections. We tested the susceptibility of 244 streptococci (96 Streptococcus pneumoniae, 105 group viridans streptococci, 32 Streptococcus agalactiae, and 11 group A beta-hemolitic streptococci) 107 Haemophilus influenzae, and 20 oxacillin-susceptible S.aureus (OSSA). The isolates were susceptibility tested against cefprozil, cefaclor and amoxicillin/clavulanic acid by the E-test method; and against cefadroxil, cefuroxime, cefetamet, erythromycin, and azythromycin by disk diffusion. The methods and the susceptibility categorization followed the National Committee for Clinical Laboratory Standards (NCCLS) procedures. Amoxicillin/clavulanic acid was slightly more active againstH.influenzae (MICs(90) 0.5microg/mL) than cefprozil or cefaclor (MICs(90) 4 and 2microg/mL respectively). Cefprozil demonstrated potent activity against streptococci. Against S.pneumoniae, cefprozil was 2-4 fold more active than cefaclor (MICs(90)0.125 and 0.38microg/mL, respectively). S. pneumoniae susceptibility was 84% to penicillin, 95% to erythromycin and 97% to azithromycin by disk diffusion. Viridans streptococci showed higher MICs for cefprozil and cefaclor (MICs(90) 4microg/mL and 8microg/mL, respectively) and only 50% susceptibility to the macrolides. Cefprozil was four times more active than cefaclor and as active as amoxieillin/clavulanic acid against group A beta-hemolytic streptococci and S.agalactiae. These three compounds showed similar activity against OSSA. In conclusion, cefprozil demonstrated excellent in vitro activity against bacterial species responsible for respiratory infections in Sao Paulo.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11101908&dopt=Abstract antibiotic amoxicillin[PubMed - as supplied by publisher]




J Clin Periodontol. 2000 Jul;27(7):520-5.
Beta-lactamase producing bacteria in the subgingival microflora of adult patients with periodontitis. A comparison between Spain and The Netherlands.

Herrera D, van Winkelhoff AJ, Dellemijn-Kippuw N, Winkel EG, Sanz M.

Laboratory of Microbiology, Faculty of Odontology, Universidad Complutense de Madrid, Spain.

BACKGROUND/AIMS: Countries with a high per capita antibiotic use frequently demonstrate a high level of drug resistance. The aim of this study was to compare the prevalence and levels of beta-lactamase producing bacteria in the subgingival microflora in adult patients with periodontitis in Spain and The Netherlands, and to characterise beta-lactamase producing bacteria in both patient samples. METHOD: Patients with moderate to severe periodontitis were consecutively selected and asked to report on: current systemic disorders and medications, history of use of antibiotics, and smoking habits. Clinical variables included probing pocket depth, clinical attachment level, plaque, bleeding on probing, and suppuration. Pooled subgingival samples of 4 selected sites were anaerobically cultured in blood agar plates with and without amoxicillin, and amoxicillin/clavulanate. Bacterial colonies growing on amoxicillin plates but not on amoxicillin/clavulanate plates were tested for beta-lactamase production. beta-lactamase producing bacteria were isolated and identified. RESULTS: 31 patients were studied in the Spanish group and 30 in the Dutch group. Comparable mean gender and ages were found. Evaluation of previous antibiotic use revealed that, in the previous 12 months, 54.8% of patients in the Spanish group and 10% in the Dutch group reported antibiotic use (p<0.001). The prevalence of beta-lactamase producing bacteria was 87.1% in the Spanish group and 73.3% in the Dutch group. Total counts of beta-lactamase producing bacteria on amoxicillin plates (p<0.01), the mean number of different beta-lactamase producing colonies per patient (p<0.001), and the number of amoxicillin resistant colonies (p<0.001) were significantly higher in the Spanish group. 74 beta-lactamase producing strains in the Spanish group and 33 in the Dutch group were isolated for identification. 23 out of 35 identified strains in the Spanish group, and 32 out of 33 in the Dutch group belonged to Prevotella genus. CONCLUSIONS: A high prevalence of beta-lactamase producing bacteria has been evaluated in two distinct populations, belonging to two European countries with clear differences in antibiotic usage policy. A higher prevalence and a more complex beta-lactamase producing microflora, were found in the Spanish group, associated with a higher antibiotic consumption. This study shows that a higher use of beta-lactam antibiotics is reflected in the % of beta-lactamase producing bacteria in the subgingival microflora of patients with periodontitis. This information may be important in the treatment of severe periodontitis.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10914894&dopt=Abstract antibiotic amoxicillin