Amoxycillin: A review of its antibacterial and pharmacokinietic properties and therapeutic use

Drug-induced enterocolitis syndrome: Similarities and differences compared with food protein-induced enterocolitis syndrome

In 2014, drug-induced enterocolitis syndrome (DIES) was described for the first time. It is still a poorly known disease with symptoms that typically resemble those of food protein-induced enterocolitis syndrome (FPIES). To date, six more cases of DIES have been described and new clinical diagnostic criteria have been proposed based on those in the international guidelines for FPIES. In this paper, the authors describe three more cases of DIES. In addition, similarities and differences with FPIES have been deeply analyzed. To date, several unanswered questions need to be addressed, but clinicians must be instructed how to identify DIES, in order to make an allergy workup and give definite therapeutic indications to patients, especially in children where DIES seems to be more frequent.

Prevalence of feline urinary tract pathogens and antimicrobial resistance over five years

The aim of this retrospective study was to document the prevalence of bacterial species in cats with significant bacteriuria and to compare their antimicrobial susceptibilities over five years. One hundred sixty-nine positive urine cultures from 150 cats were included. Fifty-five per cent showed clinical signs, while 40 per cent had subclinical bacteriuria. Escherichia coli, Staphylococcus species, Enterococcus species, Streptococcus species and Proteus mirabilis accounted for 50.5 per cent, 22.9 per cent, 15,1 per cent, 3.6 per cent and 2.6 per cent, respectively. Enterococcus species was significantly more common in cats with subclinical bacteriuria. Enterococcus species and Proteus mirabilis isolates were resistant to a significantly higher number of antimicrobials than other isolates. Applying the formula to select rational antimicrobial therapy, bacterial isolates were most likely to be susceptible to imipenem, nitrofurantoin, gentamicin and amoxicillin clavulanic acid. Over the study period, only minor differences were noted for the antimicrobial impact factors (IFs) between years and between cats with and without clinical signs. The cumulative IF increased significantly compared with the previous 10 years. Empirical treatment of bacterial cystitis should be avoided whenever possible and, if needed, based on the locally determined bacterial spectrum and antibiotic susceptibility.

History of antibiotics. From salvarsan to cephalosporins

Infections have represented for a long time the leading cause of death in humans. During the 19th century, pneumonia, tuberculosis, diarrhea and diphtheria were considered the main causes of death in children and adults. Only in the late 19th century did it become possible to correlate the existence of microscopic pathogens with the development of various diseases. Within a few years the introduction of antiseptic procedures had begun to reduce mortality due to postsurgical infections. Sanitation and hygiene played a significant role in the reduction of the mortality due to several infectious diseases. The introduction of the first compounds with antimicrobial activity succeeded in conquering many diseases. In this review we analyzed, from a historical perspective, the development of antibiotics and the circumstances that led to their discovery. The first compound with antimicrobial activity was introduced in 1911 by Erlich. He focused his research activity on the discovery of a "magic bullet" to treat syphilis. Afterwards, Foley and colleagues brought penicillin to the forefront. Streptomycin represents the first drug discovered for the treatment of tuberculosis, and its development included the first use of clinical trials. Finally, with the development of cephalosporins, the introduction of new antimicrobial compounds with broad activity against gram-positive and also some gram-negative bacteria began.

Pharmacokinetics of amoxycillin and the rate of depletion of its residues in pigs

Six pigs were used in a two-period crossover study to investigate the pharmacokinetics of amoxycillin after single intravenous and oral doses of 20 mg/kg bodyweight. Twelve pigs were used to study the residues of the drug in muscle, kidney, liver and fat after they had received daily oral doses of 20 mg/kg amoxycillin for five days. The mean (sd) elimination half life (t1/2beta) and mean residence time of amoxycillin in plasma were 3.38 (0.30) and 3.54 (0.43) hours, respectively, after intravenous administration and 4.13 (0.50) and 4.47 (0.30) hours, respectively, after oral administration. After oral administration, the maximum plasma concentration (Cmax) was 7.37 (0.42) microg/ml and it was reached after 0.97 (0.29) hours. Six days after the last oral dose, the mean concentration of amoxycillin in the pigs' kidneys was 21.38 ng/g and in the liver it was 12.32 ng/g, but no amoxycillin could be detected in fat or muscle; the concentrations of amoxycillin in edible tissues were less than the European Union maximal residue limit of 50 microg/kg.

Amoxicillin intestinal absorption reduction by amiloride: possible role of the Na(+) -H+ exchanger

Intestinal absorption of beta-lactam antibiotics has been shown to use the dipeptide carrier system. In vitro experiments have established that the efficiency of uptake by enterocytes depends on an inwardly directed proton gradient--dipeptides and beta-lactam antibiotics being cotransported along with hydrogen ion. This gradient is thought to result from the sodium-hydrogen (Na(+)-H+) exchanger located on the brush-border membrane. The aim of the present study was to assess the in vivo relevance of these data in humans by examining the effect of amiloride, a well-known inhibitor of the Na(+) -H+ exchanger, on the bioavailability of amoxicillin in eight healthy volunteers. The results show that amiloride reduces significantly amoxicillin absorption rate (mean time to maximum concentration increases from 1.0 to 1.6 hours, p < 0.05) and absolute bioavailability (by 27%, p < 0.01) and that amiloride-induced inhibition of the intestinal Na(+) -H+ exchange could be associated with an additional inhibitory effect on (Na/K)-ATPase activity. The present data seem to confirm the role of Na(+) -H+ exchange in the uptake of beta-lactams by the intestine and to support the indirect sodium dependence of this carrier system in vivo.

Roxithromycin 150 mg b.i.d. versus amoxycillin 500 mg/clavulanic acid 125 mg t.i.d. for the treatment of lower respiratory tract infections in general practice

Two hundred and forty-two patients over 16 years of age with community-acquired lower respiratory tract infection (LRTI), matched for age and sex, were randomised to receive either roxithromycin 150 mg b.i.d. or amoxycillin 500 mg/clavulanic acid 125 mg t.i.d. for 7 days, with a further 7 days if insufficient response was seen. Clinical efficacy at 7 days was 69% for roxithromycin and 56% for amoxycillin/clavulanic acid (p = 0.05) and at study end it was 91% for both antibiotics. There were fewer second treatment courses in the roxithromycin group (26% vs. 38%, p = 0.04) and a shorter treatment duration (8.29 days vs. 9.34 days, p > 0.05). Twelve patients (9.8%) treated with roxithromycin and 19 (17.1%) treated with amoxycillin/clavulanic acid had adverse effects possibly, or probably, related to the antibiotic. Roxithromycin appears to be a more appropriate choice than amoxycillin/clavulanic acid for the treatment of LRTI in the community given its more appropriate in vitro spectrum, efficacy against most common and atypical pathogens, greater cost-effectiveness, more convenient dosage regimen (b.i.d.), and superior tolerability profile.

Use of hydroxypropyl methylcellulose acetate succinate in an enteric polymer matrix to design controlled-release tablets of amoxicillin trihydrate

A controlled-release table of amoxicillin trihydrate was developed by use of a matrix formulation based on the enteric polymer hydroxypropyl methylcellulose acetate succinate (HPMCAS). Sustained drug release was shown by in vitro dissolution testing; the polymer could suppress drug release in the presence of gastric pH but could enhance drug release in the presence of small intestinal pH, compared with compacts of pure drug. Grinding or physical mixing of the drug with the polymer, an alteration in normal compaction pressure, or a substitution of other enteric polymers did not markedly affect drug release from compacts. Physicochemical testing of samples confirmed that the method of mixing did not alter powder morphology. An ethanolic granulation procedure was used in the production of final tablets (21 x 10 mm) containing amoxicillin (750 mg), HPMCAS, anhydrous directly compressible lactose, and lubricants. These large tablets showed a promising sustained-release effect in vitro when a variable-pH-shift dissolution procedure was used. However, single-dose studies with a panel of fasting subjects showed that the tablets had a relative bioavailability of only 64.4%. Other pharmacokinetic parameters confirmed a lack of therapeutic advantage of these tablets over an equivalent dose of conventional capsules.

Simple analysis of amoxycillin in plasma by high performance liquid chromatography with internal standardization and ultraviolet detection

A simple high performance liquid chromatographic method with ultraviolet detection at 229 nm is described for quantitation of amoxycillin in plasma. After deproteination of plasma samples with perchloric acid and adjustment of the pH to 4.9, the supernatant was injected onto a reversed phase C18 column, using acetonitrile:phosphate buffer (0.01 M, pH 7.4) (1:25 v/v) as the mobile phase. Amoxycillin and the internal standard, cefadroxil, were eluted at 23 min and 12 min, respectively, without interference from endogenous substances. Processed samples were stable for at least 24 h at room temperature which permitted automated batch processing overnight. Calibration plots of the amoxycillin to cefadroxil peak-height ratio vs. amoxycillin concentration were linear (P < 0.0001; r > or = 0.995) from 0.25 mg/L to at least 16.0 mg/L. Between-day and within-day imprecision (CV) ranged between 3.7% and 17.7%. Absolute recovery for amoxycillin and cefadroxil exceeded 82%. The application was demonstrated by the analysis of amoxycillin in human plasma after a single oral dose of amoxycillin (250 mg) suspension.

Synergistic effects between amoxicillin, metronidazole, and the hydroxymetabolite of metronidazole against Actinobacillus actinomycetemcomitans

Interactions between metronidazole and amoxicillin, metronidazole and its hydroxymetabolite, and amoxicillin and the hydroxymetabolite of metronidazole were investigated with checkerboard titrations in combination with accurately determined MICs and MBCs. Actinobacillus actinomycetemcomitans was used as the test organism. Synergism was found for all three combinations. Fractional inhibitory concentration indices and fractional bactericidal concentration indices varied from 0.3 to 0.7. These synergistic interactions between these antibiotics may explain the efficacy of the combination of metronidazole and amoxicillin in various bacterial infections, including periodontal disease.

The effect of amoxicillin on destructive periodontitis. A case report

In a 22-year-old female patient, advanced localized periodontal destruction was observed. The planned treatment consisted of oral hygiene instructions, professional plaque control, deep scaling and root planning and finally modified Widman flap surgery. One molar had to be extracted but was left untreated initially as a control. During the treatment period of 9 months and during 1 year thereafter, samples were taken of the subgingival plaque for dark-field microscopy. The unplanned use of amoxicillin by the patient for a middle ear infection resulted in a suppression below detection level of spirochetes at the investigated sites. At the nontreated control site, the absence of spirochetes was accompanied by a 3-mm reduction of pocket depth and a 2-mm gain in clinical probing attachment, while some formation of new alveolar bone was observed. At the treated sites, clinical improvement was observed. However, a distinction between the effect of the periodontal therapy and the nonscheduled use of amoxicillin could not be made at the treated sites. It is concluded that a single course of systematically administered amoxicillin changed the composition of the subgingival microflora over a long period of time (17 months) and had a beneficial effect upon the status of the periodontium.

A comparative study of amoxycillin and pivampicillin in persistent Haemophilus influenzae infection of the lower respiratory tract in children with chronic lung disease

A double-blind cross-over study was undertaken to compare the efficacy of amoxycillin and pivampicillin on Haemophilus influenzae infection of the lower respiratory tract in children. 20 patients with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD) due to other causes were included in the study. All patients had a history of regularly harbouring H. influenzae in sputum and repeated treatment failures with pivampicillin. 18 completed two 14-day courses in random order with equimolar doses of pivampicillin (80 mg/kg/day) and amoxycillin (62 mg/kg/day). Both drugs were well tolerated with no serious side effects, but pivampicillin was associated with more pronounced nausea. In steady state the mean serum concentrations of antibiotics 2 and 4 h after medication were 9.7 and 3.7 micrograms/ml for pivampicillin and 19.1 and 7.9 micrograms/ml for amoxycillin (p less than 0.01). Eradication of H. influenzae and clinical improvement was seen in one-third of the courses with both drugs. Betalactamase producing ampicillin-resistant strains emerged during 58% of the amoxycillin courses, but only in 16% of the pivampicillin courses (p less than 0.001). The high number of treatment failures and the development of resistant strains indicate that betalactamase inhibitors may possibly improve the efficacy of these drugs, especially of amoxycillin, in these patients.

Pharmacokinetic study of a paediatric formulation of amoxycillin and clavulanic acid in children

A combination of amoxycillin and clavulanic acid 4:1 was administered to 35 children (aged 2 to 10 years) with infections. The combination was administered orally as a suspension, every 8 h for 5 to 7 days. Sixteen children (aged 2 to 5 years), received 125 mg amoxycillin and 31.25 mg clavulanic acid, and 19 (6 to 10 years) received 250 mg amoxycillin and 62.5 mg clavulanic acid per dose. Following the first dose serum concentrations of amoxycillin and clavulanic acid were determined by microbiological assay. In the younger group receiving the lower dosage (mean: amoxycillin 9.11 mg/kg and clavulanic acid 2.34 mg/kg), the mean peak concentration of amoxycillin was 3.5 mg/l and of clavulanic acid 1.2 mg/l, occurring 1.32 h and 1.39 h, respectively, after administration. In the older group receiving the higher dosage (mean: amoxycillin 12.35 mg/kg and clavulanic acid 3.14 mg/kg) the mean peak serum level of amoxycillin was 4.0 mg/l and of clavulanic acid 1.3 mg/l, occurring 1.43 h and 1.23 h, respectively, after administration. The higher dose per kilogram body weight resulted in a higher peak serum concentration both of amoxycillin and clavulanic acid. The formulation was well tolerated by all the children and no serious side-effects were recorded. Treatment was considered clinically effective in all cases.

Antibiotic susceptibility testing of subgingival plaque samples

The in vitro inhibitory effect of several antimicrobial agents was determined against dispensed dental plaque samples taken from periodontally diseased sites as an aid in the selection of antibiotics for adjunctive use in periodontal therapy. 2 groups of patients were sampled. 1 group of 10 patients with severely advanced disease had received periodontal treatment which included the frequent adjunctive use of an antibiotic. The second group consisted of 15 individuals with less severe periodontal disease; only 4 individuals had been previously treated with antibiotics for their periodontal disease. Bacterial samples of subgingival plaque were taken from each patient and tested against a battery of antibiotics to determine which agent was the most effective in suppressing bacterial growth. Each antibiotic was incorporated into Trypticase-soy blood agar at a concentration equivalent to that achieved in either gingival fluid or blood following recommended oral dosages. The inhibitory effect was determined by comparing the number of bacterial recovered on the antibiotic-containing medium to the total number of bacteria recovered on the basal medium. Penicillins, with the exception of cloxacillin, were the most effective in inhibiting bacterial growth. Benzylpenicillin consistently inhibited the growth of 90% of the isolates recovered on media free of antibiotics while ampicillin and amoxicillin frequently inhibited 99% or more of the bacteria recovered. Tetracycline was generally inhibitory for at least 90% of the isolates if the patients had not been previously treated with this agent. However, resistance to this drug was common in samples taken from patients previously treated with tetracycline. Doxycycline, a tetracycline derivative, did not inhibit significantly more isolates than tetracycline. Clindamycin was inhibitory for 90% or more of the organisms in most of the samples; and, was usually effective in inhibiting isolates in samples which exhibited large numbers of isolates resistant to tetracycline. Erythromycin was relatively ineffective against the isolates recovered from samples from the severely diseased group but was inhibitory to isolates in some samples taken from the more moderately diseased group. Metronidazole, at the concentration tested, was largely ineffective against the isolates in bacterial samples from both groups. No single antimicrobial agent was found to be inhibitory for greater than 90% of the bacteria recovered from all of the subgingival plaque samples with the possible exception of some penicillins.

Treatment of urinary tract infections with a combination of amoxicillin and clavulanic acid

A 10-day course of amoxicillin (250 mg)-potassium clavulanate (125 mg) was administered three times daily to 116 female college students with urinary tract infections. All of the bacterial isolates from these patients were susceptible to amoxicillin-potassium clavulanate in vitro; only 81.0% were susceptible to amoxicillin alone. Evaluations at 1 week after completion of this course showed that clinical and bacteriological cures had been achieved in 96.9% of those who completed therapy. Cures were sustained in 85.6% of the patients examined at 4 weeks after the end of therapy. Therapeutic responses were comparable, irrespective of the results of antibody-coated bacteria tests. All strains of Enterobacteriaceae isolated from the rectal and urogenital sites at 1 week after therapy were susceptible to amoxicillin-potassium clavulanate. The proportion of fecal Escherichia coli resistant to amoxicillin alone increased from 13.3% before therapy to 35.6% at 1 week after therapy. Adverse drug reactions consisted of gastrointestinal symptoms (9.8%) and rashes (4.1%). Sixteen patients (14.2%) developed symptomatic candida vaginitis by 1 week after therapy.

Update on the treatment of bacterial urinary tract infections

The treatment of urinary tract infections (UTIs) has become a complex problem for the clinical practitioner. An understanding of the pharmacology, pharmacokinetics, and in vivo biological activity of antimicrobial agents is needed, as is an understanding of the variables that may influence patient compliance with medication regimens. Although UTIs are usually treated for 10 to 14 days, shorter treatment schedules of seven to ten days or even single-dose regimens are possible. Guidelines for the treatment of UTIs are presented along with suggestions for increased patient compliance.

A comparison of the side-effects of amoxycillin and pivampicillin

In 91 patients with urinary tract infections treated with amoxycillin or pivampicillin, the incidence of side-effects was high with both preparations. Although the majority of the side-effects were of minor nature, there was a significantly higher incidence of upper gastrointestinal complaints in those patients receiving pivampicillin (29.5%) as opposed to amoxycillin (6.4%).

Absorption and disposition kinetics of amoxicillin in normal human subjects

Pharmacokinetic parameters of amoxicillin were studied in healthy fasted subjects afqer both oral and intravenous administration of a single 500-mg dose. Serum levels and urinary excretion rates were determined at various time intervals by a microbiological method. The conventional two-compartment model with elimination occurring from the central compartment was used to analyze the data. Mean values were 3.40 h-1 for alpha and 0.68 h-1 for beta. Distribution constants kappa 12 and kappa 21 were 0.92 h-1 and 1.99 h-1, respectively. The rate constant for elimination from the central compartment, kappa 10, was 1.16 h-1. The volume of distribution was 20.2 liters (0.30 liter/kg), and the serum clearance was 13.3 liters/h. The absorption rate constant, kappa a, in the oral study, calculated by the Loo-Riegelman method, was 1.02 h-1, and the absorption half-life was 0.72 h. Absolute bioavailability after the oral dose was determined by comparing both the areas under the curve (AUC) and fractions of the antibiotic excreted unchanged in the urine. The AUC after oral administration was 77.4% of the intravenous AUC. On the other hand, recovery from the urine was 43.4% after the oral dose and 57.4% after the intravenous dose, indicating 76.5% bioavailability.

Bacterial kill rates of amoxycillin and ampicillin at exponentially diminishing concentrations simulating in vivo conditions

The responses of bacteria exposed to amoxycillin and ampicillin were studied at continuously decreasing levels with half-life values similar to those which could occur in vivo. For Escherichia coli, the kill-rates were higher with amoxycillin than with ampicillin. The bactericidal response was exponential. With an antibiotic half-life of one hour, the amoxycillin first order inactivation rate was 3.544 h-1 and the viable cell half-life was 0.196 h; the respective values for ampicillin were 2.341 h-1 and 0.296 h. With an antibiotic half-life of five hours, the inactivation rate was 0.704 h-1 corresponding to a viable cell half-life of 0.985 h for amoxycillin compared to 0.358 h-1 and 1.937 h respectively for ampicillin. Comparison of viable counts and photometric monitoring showed that the former is the preferable method for recording the bacterial response to these beta-lactam antibiotics. During the phase of exponential kill, a plateau occurred in the optical density values. This was due in part to an increased biomass per cell. During the recovery phase, the number of viable cells started to increase several hours sooner than did the rise in optical density. For Staphylococcus aureus,the rates of kill were similar with both agents. Amoxycillin had a long bacteriostatic phase which was not seen with ampicillin. This led to a longer lasting antibacterial effect and reduction to a lower total count with amoxycillin. With staphylococci, the viable counts and the photometric responses were parallel.

Clinical evaluation of amoxycillin in the treatment of syphilis

Following demonstration of in vitro activity of amoxycillin against Treponema pallidum, a clinical research group was set up to study the effects of amoxycillin against various stages of syphilitic infection in men. A total of eighty-nine cases, fifteen primary, twenty-nine secondary, thirty late and fifteen adult congenital patients have been investigated. One hundred per cent effectiveness was recorded for primary and secondary syphilis; 66.7% for late syphilis and 60% success for adult congenital syphilis. In 10.4% of cases there was a transient elevation of SGOT and SGPT although it is not certain whether this was a reaction to the drug itself. There were three incidences of drug-related rash and two other minor side-effects. Amoxycillin is thus a safe and effective oral agent for the treatment of all stages of syphilis in man.

[Hypersensitivity to antibiotics: Frequency, risks, cross-allergies (author's transl)]

The present paper gives a systematic review of the clinical manifestations of allergic reactions and the underlying immunological mechanisms. Attention is drawn to the relatively high proportion of cases of anaphylactic shock and serum disease related to the total number of cases of allergic reaction, and to the diagnostic techniques available for detection of sensitization towards antibiotics. Structural allergenicity is mentioned, using penicillin allergy as an example. The frequency of allergy to several antibiotics and the frequency of cross-reaction between penicillins and cephalosporins reported in the literature are discussed critically.

A comparative trial of pivmecillinam and ampicillin in bacteriuria of pregnancy

A comparative trial of pivmecillinam and ampicillin was performed on 100 women with bacteriuria of pregnancy. They received either 400 mg pivmecillinam four times daily or 500 mg ampicillin four times daily for seven days. Cure rates at two weeks were 88% in the pivmecillinam group and 85% in the ampicillin group. At six weeks the respective rates were 76% and 64%. Failure of therapy was not associated with the appearance of bacterial resistance in either treatment group. Side-effects, particularly vomiting and premature cessation of therapy, were significantly more frequent in the pivmecillinam group. No significant effects on liver function were found. In subsequent patients treated in a non-comparative manner with 200 mg pivmecillinam three times daily, the incidence of side effects was markedly reduced with no loss of efficacy.

The aminopenicillins: development and comparative properties

In this review we have compared and contrasted the antibacterial and pharmacological properties of the aminopenicillins currently available. It is apparent that there is little hard evidence (except in the case of thphoid fever) that either amoxycillin or the pro-drug esters of ampicillin are significantly more effective than ampicillin itself, despite their better absorption and higher serum levels. However, amoxycillin and the ampicillin pro-drug esters do cause fewer bowel side-effects than ampicillin, which may justify their use despite the extra cost involved. The problem of susceptibility to penicillinases is unlikely to be solved by modification of the aminopenicillin molecule. A more likely solution is administration of these substances with beta-lactamase inhibitors such as clavulanic acid. Trials with such combinations are already under way.

Review of side-effects of aminopenicillins

Side-effects of aminopenicillin therapy are reviewed on the basis of nine comparative studies of ampicillin and bacampicillin, and available literature data from investigations with talampicillin, pivampicillin, bacampicillin and amoxycillin. Diarrhoea is more common with ampicillin than with newer aminopenicillins. Exanthema do not appear more frequently with newer aminopenicillins. The frequency of upper gastrointestinal complaints in association with some of the newer aminopenicillins (amoxycillin, bacampicillin) is not more frequent than with ampicillin. All current evidence speaks in favour of a change from ampicillin to modern aminopenicillins for oral therapy.

Efficacy of single-dose and conventional amoxicillin therapy in urinary-tract infection localized by the antibody-coated bacteria technic

Urine specimens from 61 women with symptoms of cystitis who are infected with amoxicillin-sensitive organisms were examined by the antibody-coated bacteria assay. Patients with negative assays were randomized to receive either a single 3-g oral dose of amoxicillin or 10 days of amoxicillin, 250 mg, given by mouth four times per day (conventional therapy). Patients with positive assays received conventional therapy. All 43 patients without antibody-coated bacteria in the urine, 22 given single-dose therapy and 21 treated conventionally, were cured of their infection. Of 18 patients with antibody-coated bacteria, nine relapsed within one week of completion of conventional therapy. The results of the antibody-coated bacteria assay appear to predict the therapeutic response: both single-dose and conventional amoxicillin therapy are completely successful in patients with negative assays; in contrast, conventional therapy is ineffective in 50 per cent of patients with positive assays.

Haemophilus influenzae in otitis media and sinusitis: serotypes and susceptibilty to ampicillin and amoxycillin in vitro

In order to obtain Haemophilus influenzae, other than Type b, with highly probable human pathogeniticy strains were collected that had been isolated in abundant numbers from middle ear or maxillary sinus secretions of 157 patients with otitis media or sinusitis. The distribution of serotypes was as follows: nontypable 33.8%, Type b 26.1% Type a 19.1%, Type c 7.6%, Type e 5.7%, Type f 5.1%, and Type d 2.5%. The type distribution did not depend on the source of the strains. All strains were susceptible to ampicillin and amoxycillin in vitro; the broth dilution minimum inhibitory concentrations (MIC) of both antibiotics varied only fourfold; typical MIC values were 0.125 microgram/ml and 0.25 microngram/ml, respectively. Susceptibility did not vary with the source or type of the strains nor with the presence or absence of concomitant penicillin therapy.

Talampicillin: a new derivative of ampicillin

Talampicillin is a thiazolide carboxylic ester of ampicillin and is hydrolysed in the intestinal mucosa to release free ampicillin. The mean peak serum concentration of ampicillin occurred one hour after a dose of talampicillin and was about twice that attained by an equivalent dose of ampicillin. The presence of food in the stomach reduced and delayed the peak blood levels but did not affect the total amount of antibiotic absorbed or the urinary recovery. Talampicillin had less effect on the faecal flora in volunteers than ampicillin, and no overgrowth with Candida spp or Staphylococcus aureus was seen. Thirty-eight out of 47 urinary infections were eradicated by a seven-day course of talampicillin.