Urinary bactericidal activity and pharmacokinetics of enoxacin versus norfloxacin and ciprofloxacin in healthy volunteers after a single oral dose

In an open, randomised monocentric crossover study in six male and six female healthy volunteers, the urinary antibacterial activity and pharmacokinetics of enoxacin, norfloxacin and ciprofloxacin were assessed. Urine was collected up to 6 days, and venous blood samples up to 12 h, after a single oral dose of 400 mg enoxacin, 400 mg norfloxacin and 500 mg ciprofloxacin. Enoxacin (250 mg/l) demonstrated the highest peak concentration (median) in the urine (0-6 h), followed by ciprofloxacin (237 mg/l) and norfloxacin (157 mg/l) as determined by the HPLC assay. The total amount (mean) excreted by the kidneys as parent drugs were as follows: enoxacin 54% of dose, ciprofloxacin 33% of dose, and norfloxacin 22% of dose. The mean plasma concentrations decreased from 1 to 4 h after administration for enoxacin from 1.9 to 1.4 mg/l, for ciprofloxacin from 2.0 to 0.8 mg/l and for norfloxacin from 1.3 to 0.5 mg/l. The antibacterial activity in urine was determined as urinary bactericidal titers (UBT), i.e. the highest 2-fold dilution of urine still bactericidal for the reference organism (E. coli ATCC 25,922) and for five uropathogens with minimal inhibitory (MIC) and bactericidal (MBC) concentrations ranging from highly susceptible to resistant cultured from the urine of patients with complicated urinary tract infections (UTI). For the E. coli ATCC 25,922, the organism with the lowest MIC, median UBTs of ciprofloxacin were present for 4 days, decreasing from 1:512 to 1:2, that of enoxacin for 2 days, decreasing from 1:256 to 1:4, and that of norfloxacin for 2 days, decreasing from 1:128 to 1:2. For the five uropathogens (with increasing MICs: K. pneumoniae, P. mirabilis, E. coli (resistant to nalidixic acid), P. aeruginosa and E. faecalis), the UBTs decreased in general, according to MICs, demonstrating the same relations of UBTs for ciprofloxacin (highest) versus enoxacin (medium) versus norfloxacin (lowest) with one exception (P. mirabilis) for which norfloxacin showed higher UBTs than enoxacin. The minimal urinary bactericidal concentrations (MUBC), as derived from urinary concentrations, and UBTs showed a fairly wide inter- and intraindividual range and were generally higher than the corresponding MBCs as determined in Mueller Hinton broth. In conclusion, according to antibacterial activity in urine determined as UBTs, a single oral dose of ciprofloxacin (500 mg) generally resulted in the highest and longest-lasting UBTs followed by that of enoxacin (400 mg) and norfloxacin (400 mg). A dose of 400 mg enoxacin can be expected to be at least equivalent if not superior to that of 400 mg norfloxacin. Only enoxacin and ciprofloxacin exhibited urinary bactericidal activity against all test organisms up to 12 h in all individuals. Therefore, clinical comparison of enoxacin versus ciprofloxacin in the treatment of complicated UTI could be worth testing.

[Pathogenetic aspects of urinary tract infection]

Most urinary tract infections are caused by Enterobacteriaceae; E. coli-strains dominating in 50 to 80% of primary infections. Microorganisms possessing the ability to colonize the uroepithelium (fimbriae/pili) and to cytotoxically damage of cells (hemolysin) may initiate acute infections. On the other hand, properties favouring the survival of these strains in the tissue (K-antigen, iron sequestering/aerobactin) tend to produce relapse and/or chronic infection. A variety of host-specific factors, especially glycosphingolipids, on the surface of epithelial cells determine the virulence of pathogenic microorganisms in the urinary tract and the course of a disease. Structural damages resulting from intra- or extrarenal obstructions, disturbances of the urinary flow and metabolic disorders are essential, predisposing factors of a host organism. These different factors and interactions of these mechanisms determine the manifestation and course of urinary tract infections.

Evaluation of BBL CHROMagar orientation medium for detection and presumptive identification of urinary tract pathogens

The microbiological performance of BBL CHROMagar Orientation medium and CPS ID2 agar was compared to that of Columbia agar with 5% sheep blood and MacConkey agar without crystal violet for the enumeration and presumptive identification of bacteria responsible for urinary tract infections. Of a total of 658 clinical urine specimens, 118 specimens yielded no growth, 402 specimens yielded growth with cell counts of > or = 10(5) CFU/ml, and 138 specimens yielded growth with cell counts of < 10(5) CFU/ml. Of the specimens with cell counts of > or = 10(5) CFU/ml, 163 were pure cultures and 239 were mixed cultures. A total of 266 Escherichia coli organisms were isolated on both chromogenic media, 260 were isolated on blood agar, and 248 were isolated on MacConkey agar. One strain (0.4%) failed to develop the expected pink color on CHROMagar Orientation medium, and 23 strains (8.7%) failed to develop the expected pink color on CPS ID2 agar. Enterococci (CHROMagar Orientation medium, n = 266; CPS ID2 agar, n = 265) produced small blue-green colonies on both chromogenic media. Fifty of the mixed cultures contained enterococci that were detected only on the chromogenic media. The Klebsiella-Enterobacter-Serratia (KES) and the Proteus-Morganella-Providencia (PMP) groups could be identified on both chromogenic media. Of 66 isolates of the KES group, 63 grew with the expected color on CHROMagar Orientation medium and 58 of 64 isolates grew with the expected color on CPS ID2 agar. Other microorganisms required further identification. The use of chromogenic medium formulations offers a time-saving method for the reliable detection, enumeration, and presumptive identification of urinary tract pathogens. One of the greatest advantages of these media is the easy recognition of mixed cultures.

[Bacterial culture of chip tissue of enucleated prostates]

To assess the prevalence of infection and colonization of the prostate by bacteria, chip tissue samples from 166 patients undergoing retropubic prostatectomy were submitted for bacterial tissue culture. In 28 patients with an indwelling catheter before surgery, E. coli, Klebsiella, Pseudomonas and Enterobacter were the commonest species encountered, the first the most common. In only 7 patients (20%) who didn't have an indwelling catheter before operation was the culture positive. We confirmed that the longer the time the catheter was indwelling before surgery, the greater the likelihood of positive cultures. However, postoperative outcome and morbidity were not related to culture results. We conclude that even though it is worth trying to sterilize the urine and prostate before prostatectomy, the effect on the postoperative outcome is minimal when proper antimicrobial therapy is given perioperatively.

Urinary tract infections in young febrile children

UTI is a common and important clinical problem in infants and young children, with a prevalence of 5.3% among febrile infants seen in our Emergency Department. White females with rectal temperature > or = 39 degrees C are at particularly high risk (prevalence, 17%). Several studies have highlighted the limitations of the standard urinalysis for identifying UTI in infants and young children and have recommended performance of both urinalysis and urine culture. Alternative methods such as dipstick urinalysis, although attractive because of ease of performance, are inadequate as a screen for UTI. Hemocytometer WBC counts of an uncentrifuged urine specimen can be performed in an office or hospital-based laboratory with minimal training. Performance of Gram-stained smears, however, is most appropriate for the hospital-based laboratory. In the hospital setting where both tests can readily be performed, the positive predictive value of the combination of pyuria and bacteriuria (85%) allows prompt institution of antimicrobial therapy before culture results are available, whereas the lower positive predictive value of the single finding of either pyuria or bacteriuria (40%) justifies delaying treatment decisions until culture results are available. In the office setting where hemocytometer counts can easily be performed, culturing only specimens with pyuria and those of children presumptively treated with antimicrobials will result in the identification of almost all patients with true UTI, sparing large health care expenditures. Although the urine culture is traditionally regarded as the gold standard of UTI, positive urine cultures may occur secondary to contamination or in cases of ABU, leading to a false diagnosis of UTI. In contrast we found pyuria to be a reliable marker to discriminate infection from colonization of the urinary tract. The sustained absence of an inflammatory response, on repeat UA within 24 h, constitutes strong evidence that infection is absent. Management of ABU is controversial; many experts recommend withholding antibiotics because eradication of low virulence organisms may be followed by colonization with more virulent species that cause pyelonephritis. Preliminary results of our ongoing treatment trial suggest that management of young febrile children with UTI as outpatients receiving oral cefixime is as efficacious as inpatient management with intravenous cefotaxime. Results of renal ultrasound and DMSA scan at the time of infection have not modified management in any patient. Accordingly selective rather than routine performance of ultrasound is recommended. A voiding cystourethrogram at 1 month and a DMSA scan 6 months later have been valuable in identifying patients with vesicoureteral reflux and renal scarring, respectively. Among patients initially identified as having acute pyelonephritis, the incidence of renal scarring at 6 months has been substantially more frequent (approximately 40%) than we had expected. However, the long term implications of small scars identified with renal scintigraphy remain to be determined.

METHOD FOR THE DETECTION OF SIGNIFICANT BACTERIURIA IN LARGE GROUPS OF PATIENTS

A measured area of blotting paper was used as a vehicle for transferring a constant aliquot of urine on to the surface of a culture medium. The number of bacterial colonies growing in the inoculum area of the medium corresponded to the number of organisms in the urine. One thousand, two hundred and seventy-five urines from women attending an ante-natal clinic were tested by this method, and the results compared with the results of quantitative bacterial counting and of triphenyl tetrazolium chloride (T.T.C.) tests. The method was found to be a simple, cheap, and reliable way of screening urine specimens for significant bacteriuria.

Factors associated with preterm birth in Cardiff, Wales. II. Indicated and spontaneous preterm birth

OBJECTIVE

Our purpose was to examine and contrast associations of risk factors with spontaneous preterm birth and indicated preterm birth.

STUDY DESIGN

Separate multiple logistic regression analyses were performed of indicated and spontaneous preterm births in a large database of births in Cardiff, Wales.

RESULTS

Spontaneous preterm births were associated with young maternal age, low maternal weight, low or high parity, previous abortion, smoking, and early pregnancy bleeding. Indicated preterm births were associated with older age, low weight, previous stillbirth, bacteriuria, and early pregnancy bleeding.

CONCLUSION

Spontaneous and indicated preterm births have different overall profiles of association with pregnancy risk factors.

[Clinical study on antimicrobial prophylaxis following extracorporeal shock wave lithotripsy]

One hundred and sixty one patients with upper urinary stones were examined for antimicrobial prophylaxis following extracorporeal shock wave lithotripsy (ESWL). They were divided into two groups, the low-risk group (n = 133) and high-risk group (n = 28), according to the risk factors of urinary tract infection. The patients in the low-risk group were further randomized into two groups which were orally given ofloxacin for 7 days after ESWL (Group A, n = 66), no antimicrobial (Group B, n = 67). The patients in the high-risk group were randomly subdivided into three groups which were given flomoxef intravenously for 2 or 3 days and ofloxacin for 4 or 5 days thereafter (Group C, n = 10), flomoxef only for 2 or 3 days and no drugs later (Group D, n = 10), ofloxacin for 7 days (Group E, n = 8). In all of the patients in the low-risk group, during the 7 days after ESWL, fever elevation was observed in only 1.5% of patients, and bacteriuria in 10.0% on the 7th day. There was no difference in frequency of fever elevation and bacteriuria following ESWL between Group A and Group B. These findings indicate that prophylactic antimicrobial after ESWL treatment is not necessary for low risk patients with urinary tract infections. In the high-risk group, the over-all rates of fever elevation and bacteriuria were 21.4% and 24.0% respectively. The difference of effectiveness among the prophylactic regimens of the three groups (Group C, D, E) was not shown.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary sodium intake on glomerular filtration rate in partially nephrectomized dogs

Exogenous creatinine clearance rate was determined in 8 partially (approx 75%) nephrectomized dogs fed 2 concentrations of dietary sodium, beginning 9 weeks after partial nephrectomy was performed. In a double crossover design, dogs were then fed low-sodium diet (0.18% sodium on a dry-weight basis) or high-sodium diet (1.3% sodium on a dry-weight basis) in 2 sequences (L/H/L or H/L/H) for 3 consecutive 4-week observation periods. Glomerular filtration rate (GFR) was measured by exogenous creatinine clearance before and after partial nephrectomy, and every 2 weeks during the experimental diet periods. Initial mean +/- SD GFR (3.76 +/- 0.78 ml/min/kg of body weight) decreased precipitously after nephrectomy (1.25 +/- 0.45 ml/min/kg); however, during the postnephrectomy and experimental diet periods, GFR gradually increased in all dogs to nearly half the prenephrectomy values (1.87 +/- 0.22 ml/min/kg). Significant differences in GFR were not observed when dogs were fed the L/H/L or the H/L/H sequence. Therefore, it was concluded that abrupt changes from high dietary sodium (1.3%) to restricted dietary sodium (0.18%), or vice versa, does not cause deterioration of renal function in dogs with moderate renal impairment. However, caution should be used in extrapolating these findings to dogs with clinically evident (azotemia, isosthenuria) renal failure.

Pyelonephritis in male infants: how important is the foreskin?

We investigated the association of the uncircumcised foreskin and pyelonephritis in male infants less than 6 months old. During a 21-month prospective study 94 children (age range 2 weeks to 18.9 years) were hospitalized for febrile urinary tract infection. The male-to-female ratio for 35 patients less than 6 months old was 2.2:1. Of 59 patients older than 6 months the male-to-female ratio was reversed at 0.25:1 (p less than 0.001). In 13 of 24 infants (54%) less than 6 months old and in 8 of 12 boys (67%) older than 6 months a dimercaptosuccinic acid renal scan documented acute parenchymal damage (p = 0.72). Vesicoureteral reflux or other genitourinary abnormalities were found in only 3 of 24 patients (12.5%) less than 6 months old compared with 6 of 12 boys (50%) older than 6 months (p = 0.036). Of 24 infants less than 6 months old 22 (92%) were uncircumcised compared with 6 of 12 boys (50%) older than 6 months (p = 0.009). We then retrospectively compared the circumcision status of the infants who had febrile urinary tract infection with a control group of 63 infants matched for age, race and socioeconomic status hospitalized with febrile upper respiratory infection during a similar period. The frequency of uncircumcised infants in the control group with febrile upper respiratory infection was only 44% (28 of 63) compared with 91% of infants with febrile urinary tract infection (p less than 0.001). Overall the findings of the male predominance among patients less than 6 months old with febrile urinary tract infection, the disproportionately high frequency of infants with febrile urinary tract infection who were not circumcised, and the disproportionately low occurrence of vesicoureteral reflux and other genitourinary abnormalities in infants with febrile urinary tract infection strongly support an association between circumcision status and the risk for febrile urinary tract infection and pyelonephritis in male infants.

Asymptomatic bacteriuria, urinary antibody, and survival in the institutionalized elderly

OBJECTIVE

To compare clinical status of elderly institutionalized subjects with asymptomatic bacteriuria and normal urinary antibody to those with elevated urinary antibody to the major outer membrane of Escherichia coli.

DESIGN

Retrospective review.

SETTING

Long term facility for the elderly.

PARTICIPANTS

Convenience sample of 63 elderly subjects, 26% of those resident in the institution, aged 78.8 +/- 8.4 years with urine specimens collected and stored in 1987.

MAIN OUTCOME MEASURES

Differences in clinical or functional status, demographic features, and outcome during 3-years follow-up between bacteriuric subjects with normal and elevated urine antibody.

RESULTS

Thirteen subjects had no bacteriuria, and 12 had infrequent, intermittent bacteriuria; 38 (60%) had persistent bacteriuria, including four with frequent, intermittent infections. In the persistently bacteriuric group, 18 (47%) had persistently elevated urine antibody. There was no significant differences between bacteriuric residents with normal vs elevated urine antibody in clinical or functional status, age, duration of residence, or infecting organisms. However, 11 of 20 in the cohort with normal urine antibody were alive at 3 years compared to 3 of 18 with elevated urine antibody (P = 0.014).

CONCLUSIONS

Elderly institutionalized subjects with persistent bacteriuria and elevated urine antibody have decreased survival compared to those with normal urine antibody. No differences in underlying illness or clinical course to explain this survival difference were identified.