Our library of drug research abstracts drawn from the medical literature is updated on a regular schedule, and you can be assured that new amoxicillin research articles will be listed here shortly after becoming available to us.
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Medical research on amoxicillin
Jpn J Infect Dis. 2008 Nov; 61(6): 454-6
Funahashi K, Nakane K, Yasuda N, Suzuki M, Narita A, Arai N, Ahn J, Koyama N, Ushida H, Nishimura N, Ozaki T
Group A streptococcus (GAS) is a major cause of pediatric pharyngotonsillitis. In this study we determined the T serotype and antimicrobial susceptibility of GAS isolates from Japanese children. From January to December 2006, a total of 438 isolates of GAS were obtained from pharyngeal swabs of 438 children with pharyngotonsillitis. The commonest T serotype was type 1 (110 strains, 25.1%), followed by type 12 (107, 24.4%) and type 4 (77, 17.6%). All GAS isolated from pharyngeal swabs were susceptible to beta-lactams (benzylpenicillin, amoxicillin, cefotaxime, ceftriaxone, imipenem, panipenem, and cefditoren) and vancomycin, but 19.6, 19.6, 3.2, 11.6, and 27.6% were resistant to erythromycin, clarithromycin, clindamycin, minocycline, and norfloxacin, respectively. Resistance varied considerably with the T serotype. In particular, type 4 isolates had the highest resistance (67.5, 67.5, 26.0, and 53.2% were resistant to erythromycin, clarithromycin, minocycline, and norfloxacin, respectively).
Drug Dev Ind Pharm. 2008 Dec 1; 1-9
Vahdat L, Sunderland B
The stability of aqueous admixtures of amoxicillin sodium and potassium clavulanate was studied in the liquid state at selected pH values. Potassium clavulanate was found to catalyze the rate of degradation of amoxicillin sodium under the conditions of this study. In phosphate buffer (at pH 7.0) both amoxicillin sodium and potassium clavulanate showed first-order degradation when stored separately. However, when combined the rate of amoxicillin degradation increased and t(90) values for amoxicillin decreased from 69.6 min for amoxicillin alone to 10.8 min for amoxicillin in the combination at 55 degrees C. A kinetic model was developed that explained the catalytic behavior of potassium clavulanate and phosphate buffer. In acetate buffer the rate of degradation of amoxicillin sodium followed first-order kinetics, but the catalytic effect of clavulanate caused curvature in the rate plots at higher temperatures and clavulanate concentrations. This catalytic effect was less than that occurred in phosphate buffer (where the t(90) value of amoxicillin decreased from 137.3 min for amoxicillin alone to 52.5 min for amoxicillin in combination at 55 degrees C). First-order bi-exponential decay occurred with amoxicillin degradation, which explained this change in rate.
Med Sci Monit. 2008 Dec; 14(12): SC19-22
Augustin A, Shahum A, Kalavsky E, Liskova A, Kisac P, Krcmery V
The aim of this short communication is to assess colonization by MRSA, penicillin-resistant pneumococci (PRP), fluconazole-resistant (FLU-R) Candida albicans (CA) and non-albicans Candida (NAC), and ciprofloxacin-resistant E. coli with regard to immune recovery due to CD4 T-cell increase depending on the duration of highly active antiretroviral therapy (HAART). Prior exposure to oral cephalosporins (P
J Clin Microbiol. 2008 Nov 26;
Tenover FC, Emery SL, Spiegel CA, Bradford PA, Eells S, Endimiani A, Bonomo RA, McGowan JE
The goal of this study was to determine if the interpretations of extended-spectrum (ESC) and advanced-spectrum (ASC) cephalosporins for isolates of Enterobacteriaceae would be impacted by the results of aminophenylboronic acid (APBA) testing. Fifty-three isolates of Escherichia coli, 21 Klebsiella species, and 6 Proteus species that were resistant to at least one extended-spectrum cephalosporin were tested by disk diffusion with ceftazidime and cefotetan disks with and without aminophenylboronic acid (APBA). Ceftazidime disks with and without clavulanic acid (CLAV) were also tested to confirm extended-spectrum beta-lactamase (ESBL) carriage. Twenty-nine (36.3%) isolates were only APBA-test positive, 27 were only CLAV-test positive, 2 were positive with both substrates, and 22 were negative with both substrates. Thirteen (41.9%) of the 31 APBA-test positive isolates (all E. coli) tested susceptible to cefotaxime, ceftriaxone, or ceftazidime. Since clinical data suggest that AmpC-producing isolates should be reported as resistant to all ESCs, APBA testing can be helpful in identifying such organisms. Screening for AmpC-producing organisms using non-susceptibility to cefoxitin and amoxicillin-clavulanate was less specific than APBA testing; it identified ESBL as well as AmpC-producing organisms. Only 18 of 31 APBA-positive isolates were positive by PCR for an AmpC beta-lactamase gene. Thus, testing with APBA could improve the accuracy of reporting ESCs, especially for E. coli. However, results of APBA and CLAV testing did not correlate well for isolates containing both AmpC beta-lactamases and ESBLs. Thus, additional data are needed before making formal recommendations on changing ASC results.
Br J Clin Pharmacol. 2008 Dec; 66(6): 866-74
Muller AE, Dörr PJ, Mouton JW, De Jongh J, Oostvogel PM, Steegers EA, Voskuyl RA, Danhof M
AIMS: Many physiological changes take place during pregnancy and labour. These might change the pharmacokinetics of amoxicillin, necessitating adjustment of the dose for prevention of neonatal infections. We investigated the influence of labour on the pharmacokinetics of amoxicillin. METHODS: Pregnant women before and during labour were recruited and treated with amoxicillin intravenously. A postpartum dose was offered. Blood samples were obtained and amoxicillin concentrations were determined using high-pressure liquid chromatography. The pharmacokinetics were characterized by nonlinear mixed-effects modelling using NONMEM. RESULTS: The pharmacokinetics of amoxicillin in 34 patients was best described by a three-compartment model. Moderate interindividual variability was identified in CL, central and peripheral volumes of distribution. The volume of distribution (V) increased with an increasing amount of oedema. Labour influenced the parameter estimate of peripheral volume of distribution (V(2)). V(2) was decreased during labour, and even more in the immediate postpartum period. For all patients the population estimates (mean +/- SE) for CL and V were 21.1 +/- 4.1 l h(-1) (CL), 8.7 +/- 6.6 l (V(1)), 11.8 +/- 7.7 l (V(2)) and 20.5 +/- 15.4 l (V(3)) respectively. CONCLUSIONS: The peripheral distribution volume of amoxicillin in pregnant women during labour and immediately postpartum is decreased. However, these changes are not clinically relevant and do not warrant deviations from the recommended dosing regimen for amoxicillin during labour in healthy pregnant patients.
[Hepatotoxicity by antibiotics: update in 2008.]
Rev Esp Quimioter. 2008 Dec; 21(4): 224-33
Robles M, Andrade R
Although antibiotics are the most commonly incriminated drugs in instances of hepatotoxicity in medical literature. However, it is mainly due to its wide prescription and the absolute risk of hepatotoxicity related to antibiotic use is thought to be low. Nevertheless, among the different penicillins, amoxicillin-clavulanate is the single leading drug involved in hepatotoxicity in cohorts of patients with druginduced liver injury (DILI), representing between 12.8% to 14% of the cases. It is the most frequent cause of hospitalization for DILI. The incidence of amoxicillin-clavulanate induced hepatotoxicity has been estimated to be 9.91 per 100 000 users and its clinical presentation varies, the type of injury strongly influenced by age, with the hepatocelullar pattern predominating in younger patients and the cholestatic/mixed ones in older subjects. Among macrolides, erythromycin is a classical example of drug capable of inducing cholestatic injury. Recently, concern has arisen regarding telithromycin, a new generation macrolide, is hepatotoxic came from the identification of several cases of DILI related to this drug, with a typical signature, including abrupt commence of fever, abdominal pain, jaundice and ascites in some cases. Tetracyclines, especially in intravenous high doses, may be associated with dose-dependent microvesicular steatosis, and minocycline has been involved in an autoimmune like type I hepatitis. Quinolones, in spite of their extensive use in patients with cirrhosis and biliary infections, have been very rarely associated with hepatotoxicity.
Paediatr Child Health. 2006 Dec; 11(10): 647-53
Smart K, Lemay JF, Kellner JD
OBJECTIVE: To evaluate antibiotic choices and recommendations for duration of therapy made by paediatric residents (PRs) and recently graduated paediatricians (RGPs) in several typical infectious disease conditions. METHODS: In autumn 2002, a two-page questionnaire was sent to 276 core PRs in Canadian residency programs and to a random selection of 276 RGPs from across Canada. The questionnaire described 10 scenarios: otitis media, pharyngitis, sinusitis, bronchopneumonia, lobar pneumonia, meningitis, pyelonephritis, osteomyelitis, cellulitis, and fever and neutropenia. The participants were asked primarily about initial antibiotic selection and duration of treatment for each scenario. RESULTS: There were 251 participants (overall response rate of 45%). The two most common antibiotic recommendations constituted 85% or more of the total for all scenarios except acute otitis media, sinusitis, cellulitis, and fever and neutropenia. There was a twofold or more difference in the range of recommended duration of treatment for all scenarios and a threefold or more difference for sinusitis, meningitis and osteomyelitis. PRs were more likely than RGPs to use broader spectrum cephalosporins for pneumococcal pneumonia (33% versus 15%, respectively; P=0.001) and to treat sinusitis for just five to 10 days (39% versus 22%, respectively; P=0.01). Also, 33% of all participants recommended amoxicillin/clavulanate or a cephalosporin rather than amoxicillin for sinusitis. CONCLUSION: PRs and RGPs made similar and reasonable recommendations, largely in line with published guidelines, for most of the infectious disease scenarios presented. For some conditions, a significant minority of respondents unnecessarily recommended broad-spectrum antibiotics. The most variable responses were for duration of treatment, reflecting the lack of certainty in the published evidence base for many conditions.
J Endod. 2008 Dec; 34(12): 1451-6
Jacinto RC, Montagner F, Signoretti FG, Almeida GC, Gomes BP
This study assessed the prevalence and microbial interactions of Fusobacterium nucleatum and Fusobacterium necrophorum in primary endodontic infections from a Brazilian population and their antimicrobial susceptibility to some antibiotics by the E-test. One hundred ten samples from infected teeth with periapical pathologies were analyzed by culture methods. Five hundred eighty individual strains were isolated; 81.4% were strict anaerobes. F. nucleatum was found in 38 root canals and was associated with Porphyromonas gingivalis, Prevotella spp., and Eubacterium spp. F. necrophorum was found in 20 root canals and was associated with Peptostreptococcus prevotii. The simultaneous presence of F. nucleatum and F. necrophorum was not related to endodontic symptoms (p > 0.05). They were 100% susceptible to amoxicillin, amoxicillin/clavulanate, and cephaclor. Fusobacterium spp. is frequently isolated from primary-infected root canals of teeth with periapical pathologies. Amoxicillin is a useful antibiotic against F. nucleatum and F. necrophorum in endodontic infections and has been prescribed as the first choice in Brazil.
Effect of Helicobacter pylori eradication on patients with functional dyspepsia.
Rev Esp Enferm Dig. 2008 Sep; 100(9): 532-539
de Artaza Varasa T, Valle Muñoz J, Pérez-Grueso MJ, García Vela A, Martín Escobedo R, Rodríguez Merlo R, Cuena Boy R, Carrobles Jiménez JM
Objective: this study evaluated Helicobacter pylori eradication therapy in terms of symptomatic response in patients with functional dyspepsia. On the other hand, we analyzed the importance of histologic findings as a predictor of treatment response. In particular, we studied whether antral gastritis (which is associated with peptic ulcer) may predict a greater symptomatic response to Helicobacter pylori eradication in functional dyspepsia.Patients and methods: this prospective, randomized, single-center trial included 48 patients with functional dyspepsia and Helicobacter pylori infection (27 women and 21 men, mean age 37 +/- 13.5 years). Twenty-seven patients received a 10-day course of rabeprazole, amoxicillin, and clarithromycin (eradication group), followed by 20 mg of rabeprazole for 3 months. Twenty-one patients received 20 mg of rabeprazole for 3 months (control group). Patients were followed up over a 1-year period. All patients completed the Dyspepsia-Related Health Scale Questionnaire, which studies four dimensions: pain intensity, pain disability, non-pain symptoms, and satisfaction with dyspepsia-related health.Results: there was significant symptomatic improvement (p < 0.002) after 6 and 12 months, which was similar with both treatments. In the multivariate analyses, eradication therapy and less severe symptoms before treatment were the only independent factors. The symptomatic response to Helicobacter pylori eradication after 6 months was significantly greater as compared to control therapy (p = 0.01) in patients with antral gastritis and in the non-pain symptoms dimension of the questionnaire.Conclusions: both treatments proved to be clinically beneficial in patients with functional dyspepsia. We observed a tendency to greater symptomatic benefit with Helicobacter pylori eradication therapy when compared to control treatment in patients with functional dyspepsia and in a population with a high prevalence of this infection. There is a tendency to symptomatic benefit with Helicobacter pylori eradication therapy in patients with antral gastritis.
Jpn J Antibiot. 2008 Aug; 61(4): 195-208
, Kaeriyama M, Mizunaga S, Mitsuyama J, Yamaoka K, Asano Y, Sawamura H, Suematsu H, Teraji M, Tsuchiya M, Hashido H, Matsukawa Y, Matsubara S, Miyabe T, Watanabe K, Mikamo H
We investigated the susceptibility to antibacterials of 194 strains of Haemophilus influenzae isolated from medical facilities in Gifu prefecture between 2005 and 2006, and compared these results with those of 280 strains of H. influenzae isolated between 1999 and 2000. Additionally, the strains that had been separated between 2005 and 2006 were examined for beta-lactamase (BL) production, the mutation of ftsI gene coding for PBP3, the bla gene coding for TEM type of BL and the serotype. Referring to the CLSI breakpoint, H. influenzae strains were classified into the following categories: (1) beta-lactamase-negative ampicillin-susceptible (BLNAS) strains, which showed BL negative, ampicillin (ABPC) and ampicillin/sulbactam (ABPC/SBT)-MIC < or = microg/ml, (2) beta-lactamase producing ampicillin-resistant (BLPAR) strains, which showed BL producing and ABPC/SBT-MIC < or =2 microg/ml, (3) beta-lactamase-negative ampicillin-resistant (BLNAR) strains, which showed BL negative, ABPC and ABPC/SBT-MIC > or =2 microg/ml, (4) beta-lactamase-producing amoxicillin/clavulanic acid-resistant (BLPACR) strains, which showed BL producing and ABPC/SBT-MIC > or =4 microg/ml. The prevalence of each resistance class were 71.8% for BLNAS, 7.9% for BLPAR, 19.6% for BLNAR and 0.7% for BLPACR in strains isolated between 1999 and 2000. But they were 38.1% for BLNAS, 4.6% for BLPAR, 54.6% for BLNAR and 2.6% for BLPACR in strains isolated between 2005 and 2006, indicating that the percentage of BLNAS and BLPAR decreased and that of BLNAR and BLPACR increased from 1999-2000 to 2005-2006. On the basis of ftsI substitutions and having bla gene, the strains isolated between 2005 and 2006 were classified into the following distribution: 24.2% for gBLNAS, 4.1% for gBLPAR, 10.8% for gLow-BLNAR, 57.7% for gBLNAR, and 3.1% for gBLPACR-II. Ratio of BLNAR belonging to gBLNAR and gLow-BLNAR based on the ftsI substitutions and having bla gene was higher than that based on the susceptibility pattern. The MIC50 and MIC90 for those strains isolated between 2005 and 2006 were as follows; 0.0039, 0.0156 microg/ml for garenoxacin, 0.0078, 0.0156 microg/ml for tosufloxacin and ciprofloxacin, 0.0156, 0.0313 microg/ml for levofloxacin, 0.0313, 0.0625 microg/ml for norfloxacin, 0.0625, 0.25 microg/ml for piperacillin/ tazobactam, 0.0625, 0.5 microg/ml for piperacillin, 0.125, 0.25 microg/ml for ceftriaxone and cefditoren, 0.5, 1 microg/ml for cefteram, chloramphenicol and tetracycline, 0.5, 2 microg/ml for cefotaxime, 2, 8 microg/ml for ampicillin, ampicillin/sulbactam and cefdinir. In comparison with the values for the strains isolated between 1999 and 2000, the MIC50s of beta-lactam for the strains isolated between 2005 and 2006 increased over 4 times.