Reversion of High-level Mecillinam Resistance to Susceptibility in Escherichia coli During Growth in Urine

Mecillinam (amdinocillin) is a β-lactam antibiotic used to treat uncomplicated urinary tract infections (UTIs). We have previously shown that inactivation of the Escherichia coli cysB gene is the major cause of mecillinam resistance (MecR) in clinical isolates. In this study, we used different E. coli strains (laboratory and clinical isolates) that were MecR due to cysB mutations to determine how mecillinam susceptibility was affected during growth in urine compared to growth in the commonly used growth medium Mueller Hinton (MHB). We also examined mecillinam susceptibility when bacteria were grown in urine obtained from 48 different healthy volunteers. Metabolome analysis was done on the urine samples and the association between the mecillinam susceptibility patterns of the bacteria and urine metabolite levels was studied. Two major findings with clinical significance are reported. First, MecRE. coli cysB mutant strains (both laboratory and clinical isolates) were always more susceptible to mecillinam when grown in urine as compared to laboratory medium, with many strains showing complete phenotypic susceptibility in urine. Second, the degree of reversion to susceptibility varied between urine samples obtained from different individuals. This difference was correlated with osmolality such that in urine with low osmolality the MecR mutants were more susceptible to mecillinam than in urine with high osmolality. This is the first example describing conditional resistance where a genetically stable antibiotic resistance can be phenotypically reverted to susceptibility by metabolites present in urine. These findings have several important clinical implications regarding the use of mecillinam to treat UTIs. First, they suggest that mecillinam can be used to treat also those clinical strains that are identified as MecR in standard laboratory tests. Second, the results suggest that testing of mecillinam susceptibility in the laboratory ought to be performed in media that mimics urine to obtain clinically relevant susceptibility testing results. Third, these findings imply that changes in patient behavior, such as increased water intake or use of diuretics to reduce urine osmolality and increased intake of cysteine, might induce antibiotic susceptibility in an infecting MecRE. coli strain and thereby increase treatment efficiency.

Mecillinam resistance and outcome of pivmecillinam treatment in uncomplicated lower urinary tract infection in women

Pivmecillinam (PIV) is a first-line antimicrobial for treatment of lower urinary tract infection in women (LUTIW). Mecillinam, the active substance of PIV, is bactericidal mainly against gram-negative uropathogens, whereas gram-positive species are considered intrinsically resistant. However, successful treatment of LUTIW caused by Staphylococcus saprophyticus has been reported, but more rarely for other gram-positive species. The aim of this study was to compare clinical and bacteriological outcome of PIV vs placebo treatment among uropathogens with special focus on mecillinam-resistant isolates. We analysed data from a prospective, multicentre, placebo-controlled, primary health care, therapy study performed in Sweden in 1995–1998 that included 1143 women with symptoms suggestive of LUTIW. Urine cultures were collected and symptoms registered at inclusion and at follow-up visits. Overall, the efficacy of PIV was superior to that of placebo. Clinical and bacteriological outcomes of PIV treatment were similar for S. saprophyticus, Escherichia coli as for most other uropathogens irrespective of their susceptibility to mecillinam. However, the occurrence of enterococci increased nearly fivefold shortly post PIV treatment, although with mild symptoms and a high spontaneous eradication. As susceptibility to mecillinam in vitro did not predict bacteriological and clinical outcome of PIV treatment, we suggest that the present breakpoints for mecillinam should be revised.

Changing trends in the prevalence of Shigella species: emergence of multi-drug resistant Shigella sonnei biotype g in Bangladesh

Shigellosis, caused by Shigella species, is a major public health problem in Bangladesh. To determine the prevalence and distribution of different Shigella species, we analyzed 10,827 Shigella isolates from patients between 2001 and 2011. S. flexneri was the predominant species isolated throughout the period. However, the prevalence of S. flexneri decreased from 65.7% in 2001 to 47% in 2011, whereas the prevalence of S. sonnei increased from 7.2% in 2001 to 25% in 2011. S. boydii and S. dysenteriae accounted for 17.3% and 7.7% of the isolates respectively throughout the period. Of 200 randomly selected S. sonnei isolates for extensive characterization, biotype g strains were predominant (95%) followed by biotype a (5%). Resistance to commonly used antibiotics including trimethoprim-sulfamethoxazole, nalidixic acid, ciprofloxacin, mecillinam and ampicillin was 89.5%, 86.5%, 17%, 10.5%, and 9.5%, respectively. All isolates were susceptible to ceftriaxone, cefotaxime, ceftazidime and imipenem. Ninety-eight percent of the strains had integrons belonging to class 1, 2 or both. The class 1 integron contained only dfrA5 gene, whereas among class 2 integron, 16% contained dhfrAI-sat1-aadA1-orfX gene cassettes and 84% harbored dhfrA1-sat2 gene cassettes. Plasmids of ∼5, ∼1.8 and ∼1.4 MDa in size were found in 92% of the strains, whereas only 33% of the strains carried the 120 MDa plasmid. PFGE analysis showed that strains having different integron patterns belonged to different clusters. These results show a changing trend in the prevalence of Shigella species with the emergence of multidrug resistant S. sonnei. Although S. flexneri continues to be the predominant species albeit with reduced prevalence, S. sonnei has emerged as the second most prevalent species replacing the earlier dominance by S. boydii and S. dysenteriae in Bangladesh.

Secondary syphilis with exclusive peno-scrotal localization

Syphilis is a sexually transmitted disease, caused by Treponema pallidum subspecies pallidum, its incidence, in the last decade, has significantly increased both in Western World and in developing countries. It represents a global health problem: it is estimated that each year the new cases of syphilis account for about 12 millions. The diagnosis is not always easy, especially in secondary syphilis in which the cutaneous manifestations are quite variable and should be considered in the differential diagnosis. A 26-year-old homosexual man had from some days papular lesions in the scrotum and penis. Four months before he had consulted a surgeon for the presence of an ulcerated nodular lesion in the perianal area, which advised to remove it in the suspicion of cancer. The patient declined surgery while observing in the following weeks a gradual and complete disappearance of the lesion. On the basis of clinical history, clinical features and laboratory results, a diagnosis of secondary syphilis with an exclusive peno-scrotal localization was made and systemic therapy with diaminocillin was started that led to complete resolution of skin lesions and to significant reduction of sierologic values.

Uncomplicated urinary tract infections. Bacterial findings and efficacy of empirical antibacterial treatment

OBJECTIVE

To assess bacterial aetiology, antimicrobial susceptibility and efficacy of empirical treatment in uncomplicated urinary tract infections and to evaluate the dipstick as a diagnostic tool.

DESIGN

Prospective study.

SETTING

Clinical microbiology laboratory and 17 general practice clinics in Telemark County, Norway.

SUBJECTS

A total of 184 female patients between 15 and 65 years of age with symptoms of uncomplicated urinary tract infection.

MAIN OUTCOME MEASURES

Results from dipstick testing (leucocyte esterase and nitrite), bacterial culture, susceptibility patterns and efficacy of empirical antibacterial therapy on symptoms.

RESULTS

Significant bacteruria was detected in 140 (76%) of the 184 urines. The leukocyte esterase test was of little help in predicting culture-positive UTI. A positive nitrite test accurately predicted culture-positivity, while a negative result was ambiguous. The most common bacterium, E. coli, was found in 112 (80%) of the 140 positive urines and was predominantly sensitive to ciprofloxacin (100%), mecillinam (94%), nitrofurantoin (97%), trimethoprim (88%), and sulphonamide (81%), and to a lesser extent to ampicillin (72%). In 18 patients the causative bacterium was resistant to the therapeutic agent used; 7 of these returned to their GP with persisting symptoms while in 11 symptoms resolved without further treatment.

CONCLUSION

The study confirms E. coli as the predominant cause of uncomplicated UTI. Since in the majority of cases the bacterium found was susceptible to the locally preferred antimicrobials and the patients' symptoms were cured, empiric therapy is found to be an effective practice in the study area and, by inference, in others with similar antimicrobial susceptibility patterns.

[Urinary tract pathogens in uncomplicated lower urinary tract infections in women in Norway]

BACKGROUND

We wanted to investigate the antimicrobial susceptibility of urinary tract pathogens in uncomplicated lower urinary tract infections in adult women in Norway.

MATERIAL AND METHODS

Urine samples from 312 adult women with symptoms of uncomplicated urinary tract infections from eight general practices were included.

RESULTS

Significant bacteriuria was found in 187 samples (60%). E coli was isolated from 153 (82%) of these samples. Other isolated uropathogens were S saprophyticus 18 (10%), Proteus spp 6 (3%), Klebsiella spp 4 (2%), Enterobacter spp 2 (1%), enterococci 1 (0.5%) and other Gram-positive bacteria 3 (1,5%). No fungi were isolated. Of the E coli isolates, 1 %, 1 % and 9 % were resistant to nitrofurantoin, mecillinam and trimetoprim respectively. All S saprophyticus isolates were sensitive to nitrofurantoin and trimetoprim.

INTERPRETATION

Antibiotic resistance of urinary tract pathogens causing uncomplicated urinary tract infections in adult women in general practice is still low in Norway.

Effects of sulfamethizole and amdinocillin against Escherichia coli strains (with various susceptibilities) in an ascending urinary tract infection mouse model

Resistance to antibiotics used for the treatment of urinary tract infections (UTIs) is increasing worldwide. The impact of in vitro resistance on clinical outcome in UTIs requires further study, since most studies of both humans and animals have evaluated only the efficacy of antibiotics toward bacteria susceptible in vitro. We were interested in evaluating the relationship between the in vitro antibacterial effect and the in vivo efficacy after antibiotic treatment. We simulated a natural ascending UTI by use of the ascending UTI mouse model and used Escherichia coli strains with various susceptibilities to amdinocillin (mecillinam) and sulfamethizole. Mice were treated for 3 days with antibiotic doses approximating human urinary tract concentrations after a standard oral dose. For a susceptible strain (MIC, 0.5 micro g/ml) and a resistant strain (MIC, 128 micro g/ml), respectively, there were significant reductions in bacterial counts in the urine, bladder, and kidneys after treatment with amdinocillin, whereas for a strain for which the MIC was 16 micro g/ml, there was a significant reduction in bacterial counts in the kidneys only (P < 0.05). Treatment with sulfamethizole resulted in a significant reduction in bacterial counts in all samples from a susceptible strain (MIC, 128 micro g/ml) and a resistant strain (MIC, 512 micro g/ml). Infection with a sulII gene-positive strain (MIC, >2,048 micro g/ml) could not be treated with sulfamethizole, as no effect could be demonstrated in the urine, bladder, or kidneys. For amdinocillin, there was no clear-cut relationship between the in vitro susceptibility and the in vivo outcome, while for sulfamethizole, we found a relationship between the MIC for the strain and the effect in the urinary tract.

[New molecules]

Presentation of six drugs: clopidogrel, raloxifene, mecillinam, natiglinide and repaglinide, pneumococcal conjugate vaccine. For each, positive and negative arguments, questions on hold and rating.

[New drugs]

Presentation of six drugs: clopidogrel, raloxifene, mecillinam, natiglinide and repaglinide, pneumococcal conjugate vaccine. For each, positive and negative arguments, questions on hold and rating.

Environmental risk assessment of antibiotics: comparison of mecillinam, trimethoprim and ciprofloxacin

The effects of mecillinam, trimethoprim and ciprofloxacin, antibiotics used in the treatment of urinary tract infections, on the aquatic environment were assessed. Mecillinam and ciprofloxacin were both readily biodegradable (primary degradation) in activated sludge, whereas trimethoprim persisted. The toxicity of these antibiotics towards sludge bacteria, a green alga, a cyanobacterium, a crustacean and a fish were investigated; both mecillinam and ciprofloxacin were highly toxic to the cyanobacterium Microcystis aeruginosa (EC50 in the range 5-60 microg/L). Risk characterization for the aquatic environment was performed for the three compounds by calculating the predicted environmental concentration (PEC) and the predicted no-effects concentration (PNEC). A PEC/PNEC ratio of <1 indicates that, with the present pattern of use, no environmental risk is expected. PEC/PNEC ratios of <1 for present usage in Europe were found for mecillinam and trimethoprim whereas a PEC/PNEC ratio >1 was found for ciprofloxacin.

Bacterial epididymitis in the rat: a model for assessing the impact of acute inflammation on epididymal antibiotic penetration

A rat model of bacterial epididymitis was developed and characterized for use in assessing the impact of acute epididymal inflammation on antibiotic penetration into the epididymis. A 0.2 ml. intratesticular injection of a 0.5 McFarland standard suspension of E. coli resulted in histologically confirmed acute epididymitis in all animals studied. Inflammatory changes were detectable as early as 24 hours following inoculation and were progressive to the last assessment point at 11 days. Early testicular infarction was observed in association with epididymal inflammation. Serial transcrotal ultrasounds of infected animals showed progressive increase in epididymal size and a late decrease in testicular size. Serum and epididymal drug concentrations were assayed following a single dose of the antibiotic amdinocillin. Fifteen minutes following the peak serum level, the drug concentration in infected epididymis was 2.3-fold higher than the contralateral, non-infected epididymis. These data suggest that acute inflammation enhances antibiotic penetration into the infected epididymis. The model described provides a rapid, reproducible method to study epididymal drug delivery in normal and diseased states.

Efficacy of the combination pivampicillin/pivmecillinam compared to placebo in the treatment of convalescent carriers of nontyphi Salmonella

In a randomized, double blind, placebo-controlled study 36 patients aged 16-77 years who had been carriers of nontyphi Salmonella species for 10-21 weeks were given the combination pivampicillin/pivmecillinam or placebo for four weeks in order to eradicate the carrier state. 34/36 patients who fulfilled the criteria for inclusion in the study were evaluable for efficacy, 16 in the pivampicillin/pivmecillinam group and 18 in the placebo group. Seven patients in the pivampicillin/pivmecillinam group had to terminate the treatment after 10-25 days because of adverse reactions, mainly exanthema and nausea. After therapy 8/16 patients treated with pivampicillin/pivmecillinam and 4/18 patients treated with placebo had negative stool cultures for Salmonella species during a mean follow-up time of 13 and 20 weeks, respectively. No abnormalities could be found in those patients who did not respond to therapy except for earlier cholecystectomy in two patients, both in the pivampicillin/pivmecillinam group.

Norfloxacin vs. pivmecillinam in the treatment of uncomplicated lower urinary tract infections in hospitalized elderly patients

In a single-blind, randomized study of multicentre trial design 343 hospitalized geriatric patients (median age 83 years) suffering from symptomatic urinary tract infections (UTI) were treated with either norfloxacin 200 mg twice daily or pivmecillinam 200 mg 3 times daily orally for 7 days to compare the clinical efficacy and safety of the antibiotics in the elderly. The pathogen was Escherichia coli in 56.7%, other gram-negative rods in 37.2% and gram-positive cocci in 6.1%. Up to 18 days after cessation of treatment the original pathogen was eradicated in 60.5% of the 114 who were assessable for the effect of norfloxacin therapy and in 36.5% of the 96 patients in the pivmecillinam group (p less than 0.001). Adverse drug reactions, mostly gastrointestinal disturbances, were noticed in single cases.

[Acute enteritis caused by Salmonella: effect of mecillinam and cotrimoxazole on the clinical course and fecal carrier state]

In a prospective randomized study we have evaluated the influence of co-trimoxazole and mecillinam on the clinical outcome and the fecal Salmonella sp carrier status in 134 adult patients with acute non-typhi Salmonella sp enteritis. The patients were distributed in three groups on the basis of predefined clinical and biological criteria, depending on their risk of bacteremia or severe complications of it, or on the enteroinvasive character of the causative organism. The inclusion in any group determined the treatment. Seventy-six patients received mecillinam (1.200 mg/day p.o.), 36 co-trimoxazole (1.600 mg/day p.o.), both during five days, and 22 only diet. The patients were investigated after 1, 3 and 6 weeks until stool culture was negative. The isolated Salmonella strains, either in stool or blood culture, had a sensitivity of 98.3% to mecillinam and 96.9% to cotrimoxazole. Resistance did not develop during therapy. All patients had a favorable outcome, including the six with bacteremia. No differences were found regarding clinical features (diarrhea, abdominal pain, fever) or the rate of positive stool cultures in the three therapeutic groups in any of the follow-up controls. It was concluded that the administration of mecillinam or co-trimoxazole to patients with Salmonella sp enteritis is not associated with a prolongation of the state of fecal carrier or with the development of resistant strains.

Amdinocillin treatment of catheter-associated bacteriuria in rabbits

The effect of the beta-lactam antibiotic, amdinocillin, on the bacterial biofilm adherent to the Foley catheter surface, the bacterial microcolonies attached to the urinary bladder mucosa, and on planktonic bacteria in the urine was studied in a rabbit model of the closed urinary catheter drainage system. Progressively increasing the dose of antibiotic in this experimental catheter-associated urinary tract infection model first eliminated the bacterial population adherent to the bladder mucosa and then the planktonic population in the urine. The bacterial biofilm on the Foley catheter could be eradicated only by the highest dose of antibiotic (400 mg/kg). Scanning electron microscopy showed a gradual deterioration of bacterial biofilm and reduction in bacterial numbers with increasing antibiotic dosages. These data suggest that antibiotics used in short-term catheterization may reduce the serious sequelae associated with catheter-related infections by clearing the potentially dangerous bladder mucosal bacterial populations and urine planktonic bacteria.

Are prophylactic antibiotics necessary during extracorporeal shockwave lithotripsy?

A randomised clinical study was carried out on patients admitted for ESWL treatment in order to establish the requirement for prophylactic treatment with antibiotics during this procedure. Patients with clinical signs of urinary tract infection, evidence of infectious stones or a positive urine culture were excluded. All other patients were consecutively randomised into 3 groups which were given either trimethoprim + sulphamethoxazole or mecillinam (Group A), methenamine hippurate (Group B), or no treatment at all (Group C). Evaluation with respect to clinical signs of infection was done immediately after the treatment and 4 weeks later. In addition, a urine culture was performed 2 weeks after ESWL, i.e. 1 week after completing treatment with antibiotics and methenamine hippurate. With respect to infectious complications there were no differences between Groups A and C, between Groups B and C or between Group A and B+C, whereas an unexplained slightly higher infectious rate was recorded for Group B compared with Group A. In all patients the occurrence of bacteriuria was low (6.7%) despite the fact that almost 30% of patients had a ureteric catheter during the ESWL procedure. Patients with ureteric catheters did not present with more infectious complications than those without. All patients had a bladder catheter during ESWL. It was concluded that prophylactic treatment with antibiotics during ESWL treatment is unnecessary in all situations where an infectious aetiology is unlikely.

[Chemotherapeutic effectiveness of mecillinam and dioxidine in an experiment using polyresistant Escherichia coli]

Chemotherapeutic efficacy of mecillinam and dioxidine was studied on a model of Escherichia coli septicemia of albino mice caused by polyresistant variants of E. coli 675. It was shown that the presence of RI plasmid in the bacterial cells markedly lowered the mecillinam chemotherapeutic efficacy whereas the presence of R64 plasmid did not change the drug efficacy as compared to the plasmid-free controls. It was noted that the presence of RI and R222 plasmids in the pathogen cells increased the dioxidine efficacy while pKM-101 plasmid had a contrary effect. Correlation between the level of dioxidine resistance of E. coli 675 in vitro and the drug chemotherapeutic efficacy in animals was observed.

A comparison of pivmecillinam/pivampicillin and amoxycillin in acute exacerbations of chronic bronchitis

Courses of 7 days on either 200 mg pivmecillinam/250 mg pivampicillin given twice daily or 250 mg amoxycillin given three times daily were compared in 3783 general practice patients with acute exacerbations of chronic bronchitis in a single-blind parallel group study. Patients on pivmecillinam/pivampicillin had significantly more 'excellent' responses, although there was no difference in overall response between treatments. Post-treatment sputum colour and consistency and peak expiratory flow rates were significantly better with pivmecillinam/pivampicillin. The incidence of side-effects was the same for both groups (approximately 10%), although significantly more patients reported lower gastro-intestinal problems with amoxycillin. Treatment was withdrawn due to side-effects in 47 (2.5%) patients on pivmecillinam/pivampicillin and 51 (2.7%) patients on amoxycillin. Amoxycillin is a standard therapy in the treatment of patients with acute exacerbations of chronic bronchitis. In this study, however, it was shown that pivmecillinam/pivampicillin offers benefits over amoxycillin in these patients.

Comparison of three- and ten-day regimens with a sulfadiazine-trimethoprim combination and pivmecillinam in acute lower urinary tract infections

132 female hospital employees (mean age 32 years) with uncomplicated, bacteriologically verified acute lower urinary tract infection were included in a randomized study. The patients were treated for 3 or 10 days with a sulfadiazine-trimethoprim combination (500 mg + 150 mg) b.i.d. or for 3 or 10 days with pivmecillinam (500 mg) t.i.d. The first follow-up evaluation was performed 3-5 days after the treatment. In both sulfadiazine-trimethoprim groups the cure rate was 97% and in both pivmecillinam groups 80%. This difference was mainly due to the occurrence of pivmecillinam-resistant Staphylococcus saprophyticus strains. 109 patients attended the second follow-up visit about 4 weeks after treatment. The prevalences of reinfections and relapses were 18% in both 3-day regimens and 4-7% in both 10-day regimens. No side-effects were reported in the 3-day sulfadiazine-trimethoprim group, while about 20% in the corresponding 10-day group had side-effects. Side-effects were not common in patients treated with pivmecillinam.

Single-dose treatment of bacteriuria in pregnancy

Comparison of the results of single-dose treatment of urinary tract infection in women is confused by differences between published series in the duration of follow-up and in the diagnosis of infection. Pregnancy allows prolonged follow-up in a motivated population, but increases the possibility of false positive diagnosis of infection from midstream urines due to increased vulvovaginal contamination. Suprapubic aspiration (SPA) is safe in pregnancy and accurately confirms the presence or absence of bacteria in the bladder urine. Bacteriuria was diagnosed by SPA in 86 pregnant women. Thirty-seven of these were treated with a single dose of 3 g cephalexin and 49 with 3 days of cephalexin 1 g or of a combined preparation of pivmecillinam-pivampicillin. Both single-dose and 3-day treatments prevented further bacteriuria in 65% of the patients for the remainder of their pregnancies. This is similar to the results achieved with 10-day treatment. If extended trials confirm that single-dose treatment is as effective as conventional treatment with the same drug, then single-dose treatment has the advantages in pregnancy of minimal medication, good patient compliance and lack of side-effects.

The influence of renal functional changes on the intrarenal distribution and urinary kinetics of amdinocillin

The maintenance of effective therapeutic concentrations of antibiotics within the renal parenchyma is an important issue in the management of acute and chronic pyelonephritis. Available clinical data indicate that an important clinical-therapeutic correlation exists between the physiologic state of the kidney and the antibiotic concentrations that can be achieved in the medulla and papilla. Using a healthy canine model, we evaluated the influence of hydration and the state of acid-base balance upon the intrarenal distribution and urinary clearance of the semisynthetic penicillin amdinocillin. Renal physiologic activity significantly modulates the intrarenal distribution pattern of this compound. During the production of maximally acid and concentrated urine, the highest renal parenchyma levels of amdinocillin are achieved. During the latter circumstances the antibiotic undergoes distal tubular nonionic diffusion, which appears to be an important contributing factor to the high medullary and papillary concentrations of the drug. Nonetheless, at all levels of tested renal physiologic activity tissue and urine drug concentrations are adequate for the treatment of sensitive urinary pathogens.

A comparative study of Miraxid (pivmecillinam plus pivampicillin) and Augmentin (amoxycillin plus clavulanic acid) in the treatment of lower respiratory tract infections in general practice

Two treatments, pivmecillinam 200 mg plus pivampicillin 250 mg (Miraxid) given twice-daily and amoxycillin 250 mg plus clavulanic acid 125 mg (Augmentin) given three times daily were compared in two parallel groups of 388 general practice patients with acute bronchitis or acute exacerbations of chronic bronchitis. Patients with acute bronchitis (140 on Miraxid, 144 on Augmentin) received a 7-day course of treatment and those with acute exacerbations of chronic bronchitis (55 on Miraxid, 49 on Augmentin) a 10-day course of treatment. Both treatments were equally effective, with 99 (71%) patients with acute bronchitis being successfully treated with Miraxid and 107 (74%) with Augmentin. In acute exacerbations of chronic bronchitis, Miraxid was successful in 29 (53%) patients and Augmentin in 24 (49%) patients. Side-effects were reported by 26 (12%) of patients in both treatment groups. This single blind multicentre general practice study comparing twice-daily Miraxid with 3 times daily Augmentin demonstrated that both treatments were equally effective clinically and equally well tolerated.

Antimicrobial update

New and soon-to-be introduced antimicrobials are reviewed and compared with agents already in use to determine possible therapeutic and/or cost advantages. Drugs discussed are amdinocillin, ticarcillin/clavulanic acid, ceftriaxone, ceftazidime, imipenem/cilastatin, aztreonam, and quinolones.

Antimicrobial prophylaxis of travelers' diarrhea: a selected summary

This paper summarizes the published controlled studies of the prophylaxis of travelers' diarrhea in which the following drugs have been used: neomycin, nonabsorbable sulfonamides, Streptotriad, doxycycline, erythromycin, and mecillinam. These studies have shown that antimicrobial prophylaxis can be highly effective in preventing episodes of travelers' diarrhea. The protection, however, lasts only as long as the drugs are being taken; there is no evidence that subclinical infections occur while the drug is being taken. None of the data suggest that antimicrobial prophylaxis increases the probability of infection with drug-resistant enteric pathogens. In these studies few subjects have experienced adverse drug reactions; however, the number of subjects has been too small to allow determination of accurate incidence data. Antimicrobial prophylaxis for travelers' diarrhea can be effectively and safely used on an individualized basis for persons traveling to areas of high risk.

The effectiveness of a short perioperative course with pivampicillin/pivmecillinam in transurethral prostatic resection: clinical results

In a randomized control study comprising 261 patients undergoing transurethral prostatic resection (TUR), the effect of a short perioperative course with the oral combination of pivampicillin/pivmecillinam (PAPM) was analysed in 129 patients. The study was divided in 2 parts: the first 60 patients received 450 mg and the following 69 patients, 900 mg every 12 h until removal of catheter but not longer than for 1 week. 132 controls received parenterally 1 g of cefotaxime (CFT) daily throughout the study. During the first part of the study the frequency of bacteriuria in the PAPM group was 43% preoperatively and 30% 10 days postoperatively, during the second part 47% and 12%, respectively (p less than 0.025). In the CFT group the frequency of bacteriuria was reduced from 52% preoperatively to 28% postoperatively. The prophylactic effect (i.e. the protection against acquired bacteriuria) was 96% and 92% in the PAPM and the CFT groups, respectively. Preoperative bacteriuria was eliminated in 40% of the patients during first part and 69% during second part in the PAPM group, while corresponding figures were 48% and 46% in the cefotaxime group. There were 2 cases of septicemia and 5 of upper urinary tract infections throughout the study evenly distributed between the two groups. Oral pivampicillin/pivmecillinam 900 mg every 12 h was found to be a good alternative for perioperative antibiotic prophylaxis at TUR.

Therapeutic considerations in using combinations of newer beta-lactam antibiotics

The in vitro activity, pharmacokinetic interactions, and clinical efficacy of newer beta-lactam antibiotic combinations are reviewed. Combinations of beta-lactam antibiotics offer an antimicrobial spectrum similar to that of aminoglycoside-beta-lactam combinations without the renal or eighth cranial nerve toxicity of aminoglycosides. Synergistic activity with beta-lactam combinations is demonstrable in vitro against a wide variety of aerobic gram-negative bacilli, but the frequency, with which it is found is substantially less than for aminoglycoside-beta-lactam combinations. Also, in vitro antagonism can be demonstrated, particularly with combinations containing an agent capable of inducing beta lactamase. Substantial alterations in the pharmacokinetics of cefotaxime and desacetylcefotaxime have been demonstrated by the concomitant administration of mezlocillin or azlocillin. In addition, the clearance of moxalactam has been shown to be reduced by concomitant administration of piperacillin, and the clearance of oxacillin is reduced by concomitant mezlocillin therapy. Dosage reductions of these drugs may be appropriate in certain situations. Several clinical trials comparing therapy with beta-lactam combinations versus aminoglycoside-containing regimens in neutropenic patients have shown no difference in overall efficacy between the two regimens, with the possible exception of infections in persistently granulocytopenic patients and perhaps in patients with Pseudomonas aeruginosa infections. beta-lactam combinations are generally less nephrotoxic, but potentially more costly when newer compounds are included, than amino-glycoside-containing regimens. These beta-lactam combinations should be reserved for use in patients at high risk for aminoglycoside toxicity.

The effectiveness of a short perioperative course with pivampicillin/pivmecillinam in transurethral prostatic resection: bacteriological results

We analysed the bacteriological findings in 261 patients undergoing transurethral prostatic resection (TUR) and receiving either an oral course of pivampicillin/pivmecillinam (PAPM) or parenteral cefotaxime (CFT) in a randomized clinical trial. 123/261 patients had bacteriuria before TUR; 80% of the bacteria were gram-negative strains and 20% gram-positive. 88% of the strains were sensitive to PAPM and 93% to CFT but only 58% to ampicillin. The sensitivity of recurring bacteria was not influenced by the short course of PAPM or CFT. The faecal flora was influenced by the treatment with PAPM in terms of growth of Pseudomonas aeruginosa and fungi in some patients, but no resistant strains of Enterobacteriaceae were observed. The peak serum concentrations of ampicillin and mecillinam were obtained 2 hours after intake of the drug and were 4.5 micrograms/ml and 1.7 micrograms/ml respectively. The prostate tissue concentration of ampicillin and mecillinam (AM) was low.

The combination of pivampicillin and pivmecillinam versus pivampicillin alone in the treatment of acute pyelonephritis

96 patients with clinical symptoms of acute pyelonephritis were randomized to 2 weeks treatment with either a fixed combination of pivampicillin and pivmecillinam or to pivampicillin alone. If needed, treatment was first started with the respective parenteral equivalents of the drugs. Acute pyelonephritis was bacteriologically verified in 57 patients, in whom Escherichia coli was isolated in 80% of the cases, Klebsiella in 7% and Proteus mirabilis in 5%. 22 of the 39 patients excluded did not have significant bacteriuria (less than 10(8) c.f.u./l). Combination treatment was superior to pivampicillin/ampicillin alone, in terms of clinical effect, with successful treatment being noted in 93% in the combination group and in 53% in the ampicillin group (p = 0.002). The combination was also more effective bacteriologically and it did not select resistant strains in the urinary tract. Ampicillin treatment alone, was, however, associated with a significant increase in urinary strains resistant to ampicillin and to mecillinam. Unsuccessful responders had a significantly higher mean age (p less than 0.01) than successful responders. No serious side-effects were noted.

[Comparative study of the chemotherapeutic effectiveness of mecillinam, ampicillin and their combination in coli bacillary pyelonephritis in rats]

The chemotherapeutic effect of mecillinam and ampicillin was studied comparatively on rats with hematogenic obturation colibacillary pyelonephritis. The antibiotics were administered intragastrically in a dose of 100 mg/kg for 7 days. The treatment was started 24 hours after infection. When the drugs were used in combination their doses were twice as lower. When used alone mecillinam and ampicillin had a significant effect which was practically the same. A marked increase in the therapeutic effect was observed with the use of the antibiotics in combination: sterilization of the tissues of the affected kidney and prevention of development of macroscopic lesions in it in all the animals.

Nalidixic acid and pivmecillinam for treatment of acute lower urinary tract infections

Women, 15-45 years of age, with symptoms of lower urinary tract infection (UTI) were randomly treated with nalidixic acid (1 g X 3) or pivmecillinam (200-400 mg X 3) for three or seven days, respectively. Therapeutic failure, relapse, or reinfection occurred among 18% of 82 women, even though the isolated strains of gram-negative rods in these patients were susceptible in vitro to the antibiotics used. Therapeutic failure, i.e. no effect or at best only a minor effect on the symptoms, was registered in 10 of 13 cases of UTI caused by Staphylococcus saprophyticus and treated with nalidixic acid, which was consistent with the high minimum inhibitory concentrations (MIC) (128-512 micrograms/ml) of this antibiotic. S. saprophyticus was isolated in 9 of 12 patients during treatment with nalidixic acid. On the other hand, pivmecillinam therapy was clinically effective in 16 of 18 patients with UTI caused by S. saprophyticus, even though the MIC of mecillinam to these strains was considerably higher (8-64 micrograms/ml) than that vis-à-vis gram-negative rods. Thus the clinical effect of pivmecillinam was significantly better than that of nalidixic acid in cases of UTI caused by S. saprophyticus. The organism was not isolated from 14 patients receiving pivmecillinam therapy.

Comparison of long-term, low-dose pivmecillinam and nitrofurantoin in the control of recurrent urinary tract infection in children. An open, randomized, cross-over study

Thirty-five children with a history of vesicoureteric reflux or with recurrent urinary tract infections were randomly allocated to low-dose prophylactic treatment with pivmecillinam or nitrofurantoin. After 6-10 months they were crossed over to the alternate drug for another 6 months, but only 24 completed the study because of lack of compliance or intolerance to nitrofurantoin. There was no significant difference in the long-term prophylactic effect between the two drugs, the overall infection rate being 0.7/patient-year. Pivmecillinam was significantly better tolerated than nitrofurantoin (P = 0.01). Nitrofurantoin effected no major change in the faecal flora, and nearly all urinary infections occurring during long-term treatment were caused by Escherichia coli. In contrast, a marked reduction of E. coli and a marked increase in Gram-positive cocci were found in the faecal flora during treatment with pivmecillinam. Seventy per cent of infections were caused by Streptococcus faecalis and only 20% by E. coli during pivmecillinam treatment (P = 0.001).

Management of typhoid

Typhoid fever is still a major problem in developing Third World countries where socioeconomic conditions and standards of hygiene are still well below standard. Prophylaxis is far from satisfactory. However, recent developments using live oral vaccines are encouraging. Specific treatment for the disease consists of chloramphenicol or co-trimoxazole; amoxycillin and ampicillin are inferior agents but are of value in several situations because their potential toxic effects are less marked. Most other agents also have drawbacks or are relatively ineffective. In the severely toxic patient, corticosteroids seem to affect prognosis favourably. Of the many other acute complications of typhoid fever, ileal perforation is the most serious; there is still controversy concerning the respective roles of conservative and surgical management, but it is clear that individual cases must be assessed on their merit. Amoxycillin, because it is very rapidly absorbed and produces very high blood concentrations, is probably the best antibiotic for the carrier state.

A clinical comparison of pivmecillinam plus pivampicillin (Miraxid) and a triple tetracycline combination (Deteclo) in respiratory infections treated in general practice

Seven-day courses of either pivmecillinam 200 mg plus pivampicillin 250 mg (Miraxid) or a combination of tetracycline hydrochloride, chlortetracycline hydrochloride and demeclocycline hydrochloride (Deteclo) 300 mg, both given twice daily, were compared in a multicentre general practice study in 408 patients with symptoms of upper or lower respiratory tract infection. Patients were stratified into four diagnostic groups: sinusitis, otitis media, throat infections, and acute bronchitis and randomly allocated to treatment within these groups. Assessment at 7 days showed no difference in clinical efficacy between the two treatments where 193 of the 208 infections receiving Miraxid (93%) were rated as either cured or improved compared with 181 of the 201 infections treated with Deteclo (90%). At 7 days, the percentage of patients completely free of symptoms was the same for both groups (66%). The mean time for symptoms to clear was 3.9 days in the Miraxid group and 4.0 days in the Deteclo group. Side-effects were reported by significantly fewer patients in the Miraxid group (9.3%) than the Deteclo group (17.5%) (p less than 0.05) and six patients in the latter group failed to complete the course of treatment. Miraxid given twice daily for respiratory tract infections is as effective as Deteclo but causes significantly fewer side-effects.

A multi-centre general practice clinical evaluation of pivmecillinam plus pivampicillin ('Miraxid') and co-trimoxazole ('Septrin') in respiratory tract infections

Seven-day courses of either 200 mg pivmecillinam plus 250 mg pivampicillin or co-trimoxazole (800 mg sulphamethoxazole plus 160 mg trimethoprim) given twice daily were compared in a multi-centre general practice study in 318 patients with signs and symptoms of upper or lower respiratory tract infection. Patients were stratified into four diagnostic groups (sinusitis, otitis media, throat infections, and acute bronchitis) and randomly allocated to treatment within these groups. Assessments at Day 7 showed that both treatments were equally effective clinically, 154 (91%) patients in the pivmecillinam plus pivampicillin group showing clinical cure or improvement and 142 (88%) patients in the co-trimoxazole group. Side-effects were reported by 19 (11.9%) patients in the pivmecillinam plus pivampicillin group and by 24 (15.8%) patients in the co-trimoxazole group. Two patients in the pivmecillinam plus pivampicillin group and 4 patients in the co-trimoxazole group stopped treatment.

Changes during travel in the composition and antibiotic resistance pattern of the intestinal Enterobacteriaceae flora: results from a study of mecillinam prophylaxis against travellers' diarrhoea

A randomized double-blind study was carried out in a group of Danish students visiting Mexico for 2 weeks to investigate the efficacy of mecillinam when given orally in preventing travellers' diarrhoea. The subjects took either 200 mg mecillinam daily as a single dose or placebo for 14 days. Nine (56%) out of 16 taking placebo and 3 (19%) out of 16 taking mecillinam developed travellers' diarrhoea (p less than 0.05). The pathogenic aetiology was not ascertained. A complete change in the Enterobacteriaceae flora took place during travel. A highly antibiotic-resistant Enterobacteriaceae flora was acquired in Mexico in subjects on mecillinam prophylaxis as well as on placebo. Selection of mecillinam-resistant bacteria was minimal.

Amdinocillin: a novel penicillin. Antibacterial activity, pharmacology and clinical use

Amdinocillin is a novel penicillin whose antibacterial activity is derived from its ability to bind specifically and avidly to Penicillin Binding Protein-2 (PBP 2). Other beta-lactams bind almost exclusively to PBPs 1 and 3. This unique feature has prompted many investigators to predict that amdinocillin would aggressively synergize with other antimicrobials, particularly other beta-lactams. Certain features of these predictions have been realized. Amdinocillin is active alone against many gram-negative organisms. Pseudomonas and non-fermenting gram-negative bacteria, however, are usually resistant. Amdinocillin, in combination with many beta-lactams, exhibits marked synergy against many enterobacteriaceae. No such synergy can be demonstrated for gram-positive organisms or pseudomonas species. Amdinocillin is not beta-lactamase stable. Organisms which produce high levels of plasma-mediated beta-lactamase are resistant to the drug. Amdinocillin is widely distributed to most tissues of the body. It is removed by renal tubular secretion which results in prodigious levels of the drug in the urine. Co-administration of probenecid results in markedly elevated plasma levels of amdinocillin and delays its excretion. Amdinocillin has a plasma half-life of about one hour in patients with grossly normal renal function. Its half-life increases to 3 to 6 hours in anephric patients. The spectrum of adverse reactions observed with amdinocillin is similar to that of other penicillins. Amdinocillin, as a single agent, is effective in the treatment of urinary tract infections caused by susceptible strains of E. coli and klebsiella and enterobacter species. When amdinocillin is used in concert with other antimicrobials, synergy can frequently be demonstrated but it is essentially limited to gram-negative aerobic organisms. At present, insufficient data are available to precisely profile the utility of amdinocillin, either alone or in combination, in the treatment of systemic infections.

[Travellers' diarrhea. Current data on the role of enterotoxigenic Escherichia coli]

50 to 70% of diarrheas contracted during travel in hot countries are due to an enterotoxigenic E. coli having the dual acquired ability to adhere to the intestinal epithelium and to produce an enterotoxin. This produces a liquid diarrhea, usually banal for the traveller but which can sometimes be serious in young children of developing nations. The genes coding for the above two characteristics are carried by a plasmid. Other colibacilli, enteropathogenic or entero-invasive, can also cause diarrhea; being liquid in the former case and dysenteriform in the latter. Other bacteria such as the vibrions and perhaps Aeronomonas, can also secrete an enterotoxin. The role of invasive organisms and viruses is briefly discussed. The prophylaxis is fairly illusive and treatment of the mild forms is usually symptomatic.

A comparison of pivmecillinam/pivampicillin and co-trimoxazole in hospitalized patients with acute exacerbations of chronic bronchitis

Forty-nine hospitalized patients with acute exacerbations of chronic bronchitis were randomly allocated a ten-day course of either pivmecillinam/pivampicillin or co-trimoxazole. Both treatments were equally effective clinically (pivmecillinam/pivampicillin successful in 72% of cases; co-trimoxazole in 70%) and in their ability to eradicate pus from sputum (pivmecillinam/pivampicillin 84%; co-trimoxazole 74%). One patient taking co-trimoxazole ceased therapy because of persistent nausea and vomiting. No side-effects were observed in the pivmecillinam/pivampicillin group.

Pivmecillinam, co-trimoxazole and oral mecillinam in gastroenteritis due to Vibrio spp

The comparative efficacy of antibacterial therapy with pivmecillinam or cotrimoxazole and general supportive care only was studied in patients with severe bacterial gastroenteritis. Overall, treatment with antibiotics proved significantly superior to rehydration alone in 42 children. Active therapy also had a statistically beneficial effect in children infected with Vibrio cholerae and V. parahaemolyticus. Pivmecillinam and co-trimoxazole were equally effective. Pivmecillinam and oral mecillinam appeared to be of equal value in a further 22 adults infected by Vibrio spp. No side-effects were recorded in any of the subjects treated. Further investigations with pivmecillinam and oral mecillinam are advocated.