Short-course versus conventional length antimicrobial therapy for uncomplicated lower urinary tract infections in children: a meta-analysis of 1279 patients

OBJECTIVE

The objective was to compare the efficacies of single-dose, short-course (4 days or less), and standard course (5 days or greater) antimicrobial therapy for uncomplicated childhood cystitis.

METHODS

Prospective, randomized, controlled trials comparing 4 days or less of therapy (short courses) with 5 days or more of therapy (conventional therapy) were included if all of the subjects were <18 years of age, the initial infection was documented by urine culture, at least 1 subsequent culture was obtained between 3 and 30 days of enrollment, and some attempt was made to separate upper tract from lower tract infection. Composite differences among treatment groups were compared with a fixed or random effects model, depending on the test for heterogeneity.

RESULTS

Of the 517 citations identified by literature search, 37 were selected for detailed review, and 22 were included in the final meta-analysis. The overall difference in cure rates between short and conventional courses of therapy was significant (6.38%; 95% CI: 1.88% to 10.89%), favoring the conventional course. Similar results were obtained when only studies comparing the same agents in the short and conventional courses were included (7.92%; 95% CI: 2.09% to 13.8%). Short-course amoxicillin was inferior to conventional length course (difference in cure rate, 13%; 95% CI: 4% to 24%); no difference was found between short-course and conventional length courses of trimethoprim-sulfamethoxazole (difference in cure rate, 6.24%; 95% CI = -3.74% to 16.2%).

CONCLUSIONS

We conclude that single-dose amoxicillin is inadequate therapy for uncomplicated cystitis of childhood. Three days of trimethoprim-sulfamethoxazole therapy appears to be as effective as conventional length courses of the drug.

The effect of alginate on the invasion of cystic fibrosis respiratory epithelial cells by clinical isolates of Pseudomonas aeruginosa

Chronic infection in the cystic fibrosis (CF) lung is characterized by Pseudomonas aeruginosa strains that overproduce the mucoid exopolysaccharide, alginate. Previous experiments have shown that long-term survival of P. aeruginosa in the CF lung may be facilitated by increased adherence and decreased invasion of respiratory epithelial cells. Therefore, mucoid and nonmucoid clinical isolates of P. aeruginosa were assayed for their ability to associate with and invade the CF respiratory epithelial cell line, CF/T43. Association assays and gentamicin exclusion assays demonstrated that mucoid P. aeruginosa associates with and invades CF/T43 cell monolayers significantly less than nonmucoid P. aeruginosa strains (P = .004, .02). Fluorescence microscopy invasion assays confirmed these results. The differences in association and invasion by the P. aeruginosa strains were not due to differences in lipopolysaccharide phenotype or cytotoxicity for CF/T43 respiratory epithelial cells. Exogenous bacterial alginate had no effect on the invasion of CF respiratory epithelia by a nonmucoid strain. Invasion assays with the wild-type P. aeruginosa strain PAO1 and isogenic algU and mucA mutant strains failed to show differences in invasion (P = .25). We conclude that (i) mucoid P. aeruginosa isolates associate with and invade CF/T43 respiratory epithelial cells with less efficiency than nonmucoid P. aeruginosa, (ii) these differences are not due to variations in lipopolysaccharide phenotype between strains, (iii) neither exogenous nor endogenous alginate affects the ability of P. aeruginosa to invade CF/T43 respiratory epithelial cells, and (iv) invasion of CF/T43 respiratory epithelial cells by a laboratory reference strain of P. aeruginosa does not appear to be regulated by AlgU.

Use of the paraffin wax baiting system for identification of Pseudomonas aeruginosa clinical isolates

Pseudomonas aeruginosa is the primary pathogen among the Pseudomonads and is known for its minimal nutritional requirements, capacity to use paraffin as a sole carbon source, and biofilm formation. Because the ability of Pseudomonads to grow on paraffin is not commonly found among human pathogens and the primary Pseudomonas human pathogen is P. aeruginosa, we studied the adaptation of the paraffin baiting system for the growth and identification of clinical isolates of P. aeruginosa. We also studied the effectiveness of combining a fluorescence assay measuring fluorescein (pyoverdin) production and oxidase test with the paraffin baiting assay for P. aeruginosa speciation. Strains were tested for the capacity to use paraffin as a sole carbon source using the paraffin baiting system with Czapek's minimal salt medium. Of 111 P. aeruginosa clinical isolates tested for using paraffin as a sole carbon source, 45% exhibited growth on paraffin at 24 h and 76.6% exhibited growth on paraffin at 48 h. The ability of the reference strains and clinical isolates were then tested for their ability to associate with the paraffin slide in the presence of an additional carbon source. Of 111 P. aeruginosa clinical isolates tested, 85 strains (76.6%), and 102 (93%) were associated with the paraffin surface at 24 and 48 h. We successfully combined fluorescence and oxidase assays with the paraffin baiting system for identification of P. aeruginosa. The simple and inexpensive paraffin baiting system is a useful method for the identification and study of P. aeruginosa suitable for both the clinical and research laboratory.

Prophylactic antibiotics with intracranial pressure monitors and external ventricular drains: a review of the evidence

BACKGROUND

The role of prophylactic antibiotics (PABs) in preventing infections associated with intracranial pressure (ICP) monitors and external ventricular drains (EVD) is not well defined.

METHODS

This study includes an analysis of published reports and a survey of current practices regarding the use of PABs with ICP monitors and EVDs. A computerized data search and a review of the abstracts from two major national neurosurgical meetings over the past decade yielded 85 related articles. Three independent investigators, blinded to the title, author(s), institution(s), results, and conclusions of the articles used predetermined inclusion criteria to select studies for meta-analysis. Thirty-six responses were returned from 98 questionnaires (37%) mailed to university neurosurgical programs.

RESULTS

Among the articles reviewed, only two studies met the predetermined inclusion criteria for the meta-analysis, and they were of insufficient size to produce statistically significant results. Among the 36 programs that responded to the survey, 26 (72%) used PABs, mainly cephalosporins (46%) and semisynthetic penicillins (38%), with ICP monitors and EVDs. Twenty-two (85%) used one drug, and 4 (15%) used two drugs. Twenty-two (61%) of the total group reported intra-institutional variation in practices among individual staff neurosurgeons. Nineteen (53%) expressed interest in a retrospective study, and 27 (75%) expressed interest in a prospective study on the role of PABs in minor neurosurgical procedures.

CONCLUSION

No consensus regarding the use of PABs with ICP monitors and EVDs is noted. Randomized controlled trials of sufficiently large size with appropriate blinding are needed to address this issue.

Reduced interleukin-8 production by cystic fibrosis airway epithelial cells

The acquisition of Pseudomonas aeruginosa in the airways of patients with cystic fibrosis (CF) is the initial event leading to bronchiectasis and lung disease. Although the host factors that permit initial airway colonization are largely unknown, recent studies suggest that secretion of interleukin (IL)-8 by airway epithelia and local recruitment of neutrophils is the final pathway in a pulmonary cytokine network. To determine whether differences in cytokine production exist between normal and CF airway epithelia, secretion of immunoreactive IL-8 and IL-10 as well as specific messenger RNA (mRNA) abundance were compared in airway epithelia expressing normal and mutant CF transmembrane regulator. After induction with IL-1beta, a CF airway cell line engineered to express the wild-type CF gene (CFT1-LCFSN) secreted significantly more immunoreactive IL-8 than did its isogenic parent that expressed the mutant CF gene (CFT1) or an isogenic vector control line (CFT1-LC3). Further studies with the three related cell lines demonstrated that expression of CFT1-LCFSN was associated with a significant increase in uninduced secretion of immunoreactive IL-8 as well as a 10- to 20-fold increase in IL-8 mRNA abundance when compared with the isogenic lines expressing the mutant gene. IL-1beta induction and intracellular accumulation of IL-8 appeared to be unaffected by CF genotype. These studies suggest that IL-8 secretion by CF airway epithelial cells is defective and may contribute to Pseudomonas persistence in the CF airway. Further studies are needed to confirm this difference in other cell lines and determine the linkage between IL-8 production and CF gene expression.

Multidisciplinary evidence-based medicine journal clubs: curriculum design and participants' reactions

BACKGROUND

Evidence-based medicine (EBM) is becoming an accepted educational paradigm in medical education at a variety of levels. It focuses on identifying the best evidence for medical decision making and applying that evidence to patient care.

METHODS

Three EBM journal clubs were developed at the West Virginia University School of Medicine. One was for senior medical students, another for residents, and the third for primary care faculty members. In each, the sessions stressed answering clinical questions arising from actual patient-care issues. The curricular structure and development of the journal clubs are described. Participants anonymously evaluated aspects of the journal clubs regarding their educational value with Likert scale questions.

RESULTS

Faculty members and residents generally gave high evaluations to all aspects of the EBM journal clubs. Student evaluations were more mixed. For each of the evaluation questions, the student means were lower than those of faculty and residents. However the differences reached statistical significance only in the responses to the usefulness of the sessions in understanding the medical literature (P < 0.01). Residents and faculty rated the EBM sessions more favorably than grand rounds or the resident lecture series.

CONCLUSIONS

The establishment of evidence-based medicine journal clubs is feasible, and learners seem to value the sessions. More developed learners may gain more from the experience than those earlier in their medical education.

Effects of pentoxifylline on sputum neutrophil elastase and pulmonary function in patients with cystic fibrosis: preliminary observations

High concentrations of free human neutrophil elastase in bronchial epithelial fluid are believed to be a major factor in the evolution of pulmonary injury in cystic fibrosis (CF). To test this hypothesis, we studied pentoxifylline, a compound that inhibits tumor necrosis factor alpha transcription and its stimulatory effect on polymorphonuclear neutrophils, in patients with CF who had chronic Pseudomonas bronchitis. Subjects older than 11 years of age randomly received placebo or pentoxifylline (1600 mg/day) orally, in a double-blind fashion, for 6 months. Pulmonary function and sputum elastase concentrations were determined before therapy and bimonthly during therapy; compliance was determined by measuring serum drug concentrations. Of the 16 patients who completed the study, 9 received pentoxifylline. The sputum elastase concentrations among placebo recipients were significantly increased from baseline at 4 and 6 months (F = 3.44; p < 0.05); the values remained unchanged in the treatment group. The mean forced vital capacity for the placebo group decreased from 59.2% +/- 15.4% predicted at baseline to 52.0% +/- 12.9% predicted at 6 months; the values in the treatment group remained largely unchanged. The forced vital capacity improved between baseline and 6 months for four of nine pentoxifylline recipients and none of the seven control patients (p = 0.09). During the study, four of seven placebo recipients experienced a significant pulmonary exacerbation compared with one of nine treated patients (p = 0.077). These findings support the hypothesis that polymorphonuclear neutrophil elastase is a factor in the evolution of CF lung disease; further studies are needed to define the role of pentoxifylline in the treatment of CF.

Effective short-course treatment of acute group A beta-hemolytic streptococcal tonsillopharyngitis. Ten days of penicillin V vs 5 days or 10 days of cefpodoxime therapy in children

OBJECTIVE

To compare bacteriologic and clinical efficacy and safety of 10 vs 5 days of cefpodoxime proxetil vs 10 days of penicillin V potassium for the treatment of acute group A beta-hemolytic streptococcal tonsillopharyngitis in children.

DESIGN

Prospective, randomized, observer-blind, multicenter study.

PATIENTS/INTERVENTIONS

Four hundred eighty-four children (age range, 2 to 17 years) with signs and symptoms of acute tonsillopharyngitis were enrolled; 377 had a positive throat culture for group A beta-hemolytic streptococci and were fully evaluable. One hundred twenty-one patients received cefpodoxime once a day for 10 days, 126 received cefpodoxime twice a day for 5 days, and 130 received penicillin V three times a day for 10 days.

RESULTS

Cefpodoxime for 10 days vs cefpodoxime for 5 days vs penicillin V for 10 days produced bacteriologic eradication at the end of therapy in 95%, 90%, and 78% of the patients, respectively. The 10- and 5-day cefpodoxime treatment regimens were more efficacious than penicillin V (P = .003 and P = .02, respectively). The cumulative bacteriologic failure rate among assessable patients by the 32- to 38-day posttreatment visit was 20 (17%) of 121 patients who were treated with cefpodoxime for 10 days, 24 (19%) of 125 patients who were treated with cefpodoxime for 5 days, and 45 (35%) of 130 patients who were treated with penicillin V for 10 days (P = .001 and P = .005, respectively). Clinical cure or improvement was observed at the end of therapy in 96%, 94%, and 91% of the patients, respectively (P = not significant). Adverse events were infrequent and similar in all three treatment groups, with minor gastrointestinal side effects predominating.

CONCLUSIONS

Five days of treatment with cefpodoxime is as efficacious in bacteriologic eradication and clinical response (cure plus improvement) as 10 days of cefpodoxime therapy, and both cefpodoxime regimens produced superior bacteriologic efficacy compared with a 10-day regimen of penicillin V in the treatment of group A beta-hemolytic streptococcal tonsillopharyngitis in children.

Longitudinal serum IgG response to Pseudomonas cepacia surface antigens in cystic fibrosis

In cystic fibrosis (CF), serum antibody against surface antigens of Pseudomonas aeruginosa is detected only after colonization. Since pulmonary acquisition of P. cepacia usually follows colonization with P. aeruginosa and since P. aeruginosa-colonized patients with CF have demonstrable antibody against outer membrane proteins of P. cepacia, it appears that acquisition of the latter organism occurs in the presence of specific serum antibody. To test this hypothesis, serum obtained from six P. aeruginosa-colonized patients 4 and 2 years prior to and 3 months and 2 years after P. cepacia colonization were assayed for total and specific IgG to P. cepacia outer membrane components. Four patients demonstrated 6-fold or greater increases in specific IgG titers to whole outer membranes following colonization. By immunoblot, all patients had demonstrable serum IgG against the 27- and 36-kDa outer membrane proteins of P. cepacia 4 and 2 years prior to colonization. Immunoblots after P. cepacia acquisition demonstrated an intensification of the 28- and 36-kDa bands and the appearance of antibody to a very low molecular weight compound which was not hydrolyzed by proteinase K and was present in purified LPS. These observations suggest that low serum titers of antibody against two P. cepacia outer membrane proteins are present in patients with CF prior to P. cepacia colonization, and that these antibodies fail to protect for intrinsic or extrinsic reasons.

The effect of sodium on amiloride-tobramycin synergy in Pseudomonas cepacia

Amiloride combined with subinhibitory concentrations of tobramycin is synergistic against Pseudomonas cepacia in vitro. It is known that amiloride blocks transmembrane sodium (Na+) flux in eukaryotic cells, but the mechanism of action in bacteria is unknown. Amiloride-mediated Na+ gradient changes might affect transcellular tobramycin transport, resulting in synergy between these two drugs. To examine this hypothesis, we studied the effect of extracellular [Na+] on amiloride-tobramycin synergy with a reference strain of P. cepacia. Control growth in Mueller-Hinton broth (MHB) alone, MHB supplemented with 200 mmol/L NaCl, and MHB dialyzed against a Na+-free solution was determined by absorbance at 650 nm over 3 hours. Inhibition in the presence of amiloride, tobramycin, or a combination was expressed as percentage of control growth. Growth in the presence of tobramycin alone was significantly higher in MHB + NaCl than in MHB or dialyzed MHB (81% +/- 5%; vs 57% +/- 5%; 35% +/- 4%; mean +/- SEM, respectively, p = 0.003). Growth in the presence of amiloride alone was not significantly different in the three media (84% +/- 4%; 80% +/- 3%; 80% +/- 1%; respectively, p = 0.746). Percent control growth was significantly lower when the two drugs were combined, but results were not statistically different among the three media (3.5% +/- 3%; 0.2% +/- 0.8%; 4% +/- 1%; respectively, p = 0.604). We conclude that growth inhibition of P. cepacia in the presence of tobramycin is antagonized by increasing extracellular [Na+]. This antagonistic effect of [Na+] is reversed by amiloride. Changes in [Na+] do not appear to directly affect amiloride-tobramycin synergy in P. cepacia.

The emergence of beta-lactam resistance among strains of Enterobacter cloacae and Pseudomonas aeruginosa

The development of multiresistant bacterial strains associated with the use of the new beta-lactam antibiotic agents has prompted investigation into the mechanisms involved. Factors influencing beta-lactamase production, alterations of target-protein structure or production and decreases in bacterial outer membrane permeability have been identified as the three general mechanisms of beta-lactam resistance in aerobic Gram-negative bacteria. Because there is no DNA interaction by beta-lactam agents, emergence of resistance results from either spontaneous mutation or the presence of resistant subpopulations; the presence of antibiotics allows for overgrowth of resistant strains. Studies have indicated that there is a significant relationship between the rate of emerging resistance and the ratio of the minimum inhibitory concentration of a beta-lactam to the drug concentration used to select for resistance in vitro or achieved at the infection site in vivo. It is concluded that the use of synergistic combinations of agents should reduce the emergence of beta-lactam-resistant bacterial strains. Thus the choice of an appropriate therapeutic agent requires thorough evaluation of the specific pathogen for susceptibility to a variety of beta-lactam agents and aminoglycosides.

In vitro activity of YTR 830

YTR 830, now known as tazobactam, is a new penicillanic acid sulfone beta-lactamase inhibitor. The in vitro activity of YTR 830 combined with various penicillins was determined and compared to that of clavulanate and sulbactam combined with the same agents. Combined with ampicillin or amoxicillin, all three inhibitors were active against beta-lactamase producing strains of Staphylococcus aureus, Haemophilus influenzae, Klebsiella, Citrobacter diversus, and all anaerobes except for Bacteroides fragilis homology group II. YTR 830 was also effective against Escherichia coli and indole-positive Proteus. The inhibitors had no effect against Enterobacter or Serratia. Overall, the activity of YTR 830 was comparable to that of clavulanate, and superior to that of sulbactam.

Outer membrane permeability in Pseudomonas cepacia: diminished porin content in a beta-lactam-resistant mutant and in resistant cystic fibrosis isolates

Since beta-lactam resistance is a feature of Pseudomonas cepacia isolates causing pulmonary infections in cystic fibrosis (CF), this study was undertaken to determine whether alterations in beta-lactam permeability mediate drug resistance in this species. A beta-lactam-susceptible non-CF isolate (strain 75-26), a resistant mutant derived from 75-26 by selection for cross-resistance to ciprofloxacin and ceftazidime, and two resistant CF isolates of P. cepacia were used. Permeability constants were calculated from the rate of nitrocefin hydrolysis in intact bacterial cells. Qualitative changes in outer membrane proteins were determined electrophoretically. The permeability constants of the mutant and the resistant CF isolates were lower than the value for the reference strain, 75-26. Whereas the lipopolysaccharide side chains were present in the test and reference strains, the resistant mutant and the CF isolates contained reduced amounts of the 36-kilodalton (kDa) outer membrane protein and failed to express the 27-kDa outer membrane protein. These observations suggest that the 27-kDa outer membrane protein may be a major porin or a major protein component of the porin complex in P. cepacia and that decreased expression of the 36-kDa outer membrane and loss of the 27-kDa porin are associated with high-level beta-lactam resistance in some CF isolates of P. cepacia.

Serum IgG antibody to outer membrane antigens of Pseudomonas cepacia and Pseudomonas aeruginosa in cystic fibrosis

IgG antibody to the outer membrane of Pseudomonas cepacia was quantified in sera from controls without cystic fibrosis (CF) and from Pseudomonas aeruginosa- and P. cepacia-infected and noninfected patients with CF. The mean antibody titer in the P. cepacia-infected group was significantly higher than that in the other three groups; the mean titer in the P. aeruginosa-infected group was significantly higher than that in the noninfected and control groups. Preabsorption of CF sera with P. cepacia outer membrane produced a significantly lower mean antibody concentration than did matched samples preabsorbed with an equal amount of lipopolysaccharide. By western blot, significantly more P. cepacia-infected patients produced IgG to the 27- than the 36-kilodalton (kDa) porin protein of P. cepacia; 12 of 16 P. aeruginosa-infected patients produced IgG to the 27-kDa porin. Sera from all patients in both groups contained IgG to the porin protein of P. aeruginosa by western blot. We conclude that the 27-kDa porin of P. cepacia is antigenic in most P. cepacia-infected patients with CF and that some P. cepacia outer membrane components may be antigenically related to those of P. aeruginosa.

The effect of exocrine pancreatic function on chloramphenicol pharmacokinetics in patients with cystic fibrosis

The effect of exocrine pancreatic function on the pharmacokinetics of the choramphenicol oral capsule (CAP-base), chloramphenicol palmitate oral liquid (CAP-P), and chloramphenicol succinate intravenous (CAP-S) formulations was evaluated in 10 patients, aged 16-30 yr, with cystic fibrosis. Pancreatic insufficiency was assessed in each patient by measuring the absorption of p-amino-benzoic acid after oral administration of N-benzoyl-L-tyrosyl-p-aminobenzoic acid which requires chymotrypsin to cleave p-aminobenzoic from the parent molecule. In a controlled cross-over design, the overall biodisposition of each formulation was assessed in each patient with or without concurrent administration of oral pancreatic enzymes. The relative amounts of active chloramphenicol available in systemic circulation was CAP-base greater than CAP-S greater than CAP-P. Pancreatic enzyme replacement had little effect on the biodisposition parameters for the CAP-base and CAP-S formulation, but significantly increased the peak concentration and bioavailability of the CAP-P formulation. Although pancreatic enzyme replacement improved the absorption characteristics of the CAP-P formulation, absorption remained prolonged and unreliable. Serum concentration-time profiles for either CAP-base or CAP-S consistently exceeded the MIC of important nonpseudomonal pathogens. This finding was not observed after CAP-P administration independent of pancreatic enzyme replacement. The results of this study support the continued clinical use of either CAP-base or CAP-S, but the cautious use of CAP-P formulations in CF patients with concurrent pancreatic insufficiency.

In vitro activity of amiloride combined with tobramycin against Pseudomonas isolates from patients with cystic fibrosis

The diuretic amiloride has been under recent investigation as adjunctive therapy for pulmonary disease in children with cystic fibrosis (CF). In preliminary studies, the antimicrobial activity of this agent alone or combined with beta-lactam agents against reference strains of Pseudomonas aeruginosa and P. cepacia was poor; however, amiloride was markedly synergistic with tobramycin against P. cepacia. The purpose of this study was to determine the extent of amiloride-tobramycin synergy against CF respiratory isolates of P. aeruginosa, P. cepacia, and P. maltophilia. The MICs of tobramycin and amiloride alone against the Pseudomonas test strains were determined by agar dilution. Synergy was determined by combining each of four subinhibitory concentrations of amiloride (at least fourfold below the MIC) with doubling dilutions of tobramycin and comparing the MIC of tobramycin alone and in combination for each strain. At the highest concentration tested, the drug combination synergistically inhibited 50% of the P. cepacia strains tested; the combination was synergistic against fewer isolates of P. aeruginosa and P. maltophilia. Only P. cepacia was inhibited by tobramycin combined with amiloride at achievable airway concentrations. We conclude that the combination of tobramycin and amiloride may be potentially useful in the treatment of P. cepacia infections in children with CF.

Derepressed beta-lactamase production as a mediator of high-level beta-lactam resistance in Pseudomonas cepacia

A mechanism of high-level resistance to readily and poorly hydrolyzable beta-lactam substrates in Pseudomonas cepacia was identified using a hypersusceptible, beta-lactamase-inducible, non-CF clinical isolate, 75-26, and a drug-resistant mutant derived from this strain. Inoculation of 75-26 onto agar containing 16 micrograms/ml of ceftazidime produced a stable, beta-lactam-resistant mutant at a frequency of 1.7 x 10(-5). Baseline beta-lactamase production by a representative mutant isolate (75-26z) was almost 40-fold greater than the parent. Both strains produced major beta-lactamase bands with isoelectric points of 6.9, 7.8, 8.1, 8.5, and 9.2 by isoelectric focusing. Compared with the parental strain, multiple satellite bands associated with the major beta-lactamase bands were present in the mutant. Growth of an indicator strain, E. coli ATCC 25922, was inhibited by ceftazidime and piperacillin but was not inhibited after the compounds were preincubated with the beta-lactamase preparation from 75-26z. Preincubation of ceftazidime with beta-lactamase, followed by the addition of a beta-lactamase inhibitor, inhibited the growth of the indicator strain; piperacillin failed to inhibit growth of the indicator strain in a similar experiment. One mechanism of high-level resistance to both poorly and readily hydrolyzable beta-lactam substrates in P. cepacia is derepressed chromosomal beta-lactamase production.

Pseudomonas aeruginosa as a primary pathogen in children with bacterial peritonitis

This prospective study compared the efficacy of sulbactam/ampicillin and clindamycin/gentamicin in the treatment of children with bacterial peritonitis. Of the 29 children enrolled, 17 were evaluable; eight received sulbactam/ampicillin/gentamicin and nine clindamycin/gentamicin. Sixteen patients were previously healthy children with appendicitis. An average of 3.6 bacterial species were recovered from the peritoneal fluid of each patient. E coli and B fragilis were the most common aerobic and anaerobic isolates, recovered from 15 and ten patients, respectively. Pseudomonas aeruginosa was recovered from seven of 17 children; the three children with P aeruginosa infections randomized to the sulbactam/ampicillin group received gentamicin in addition to the investigational agents throughout the treatment course. Although the study groups were small, there was no difference in age, sex, number of pathogens per patient, duration of hospitalization, toxicity, or treatment failures between the two treatment groups or between children infected with P aeruginosa and controls. As a result of the high prevalence of P aeruginosa in the peritoneal exudate of otherwise healthy children with appendicitis, initial antimicrobial therapy in this patient population should include agents effective against this organism.

Factors that influence the evolution of beta-lactam resistance in beta-lactamase-inducible strains of Enterobacter cloacae and Pseudomonas aeruginosa

Induction ratios were determined for beta-lactamase-inducible strains of Enterobacter cloacae and Pseudomonas aeruginosa by using 10 beta-lactam agents. For E. cloacae, pre-incubation with ceftriaxone, cefoxitin, cefamandole, cefoperazone, or imipenem produced significantly larger amounts of beta-lactamase than did pre-incubation with moxalactam, clavulanate, ceftazidime, or aztreonam. For P. aeruginosa, imipenem was the best inducer, whereas ceftriaxone, piperacillin, cefoperazone, cefamandole, clavulanate, and aztreonam were poor beta-lactamase inducers. The rate of emergence of resistance by E. cloacae p99 and P. aeruginosa ATCC 27853 did not correlate with the induction ratio of the selecting agent; however, a strong correlation was noted between the mutation rate and the ratio of the MIC to the concentration of selecting antibiotic used. Emergence of resistance is related to the MIC of the antibiotic and the concentration of antibiotic used to select for resistance and is independent of the efficacy of the beta-lactam inducer. Resistant mutants arise through both beta-lactamase-dependent and -independent mechanisms.

Sultamicillin in the treatment of superficial skin and soft tissue infections in children

Fifty-two children with superficial skin and soft tissue infections were randomized to receive sultamicillin or cloxacillin for 7 days. Twenty-one children in each group finished the study. A total of 16 of 21 in the sultamicillin group and 13 of 21 in the cloxacillin group were cured. One child in the sultamicillin group and two in the cloxacillin group failed therapy. Four children who received sultamicillin and six who received cloxacillin had recurrences of lesions. Differences were not statistically significant.

Differences in drug susceptibility between isolates of Pseudomonas cepacia recovered from patients with cystic fibrosis and other sources and its relationship to beta-lactamase focusing pattern

Pseudomonas cepacia, a significant pulmonary pathogen among children with cystic fibrosis (CF), often possesses an inducible beta-lactamase. The beta-lactamase isoelectric focusing pattern and beta-lactam susceptibility of CF and non-CF isolates of P. cepacia were compared. Against all of the test strains, ceftazidime and piperacillin were more effective than aztreonam. More CF isolates were resistant to 8 micrograms/ml of ceftazidime than non-CF isolates. Isoelectric focusing of cefoxitin-induced, cell-free preparations of the CF isolates produced significantly more bands than comparable preparations of non-CF isolates. Organisms producing a beta-lactamase band that focused in the pH range of 8.5 to 8.7 were significantly more resistant to 8 micrograms/ml of ceftazidime than other isolates. The increased resistance of CF isolates of P. cepacia to ceftazidime may be the result of the production of a specific bacterial beta-lactamase.

Efficacy and safety of sequential treatment with parenteral sulbactam/ampicillin and oral sultamicillin for skeletal infections in children

Nine children with osteomyelitis and/or septic arthritis were treated sequentially with parenteral sulbactam/ampicillin and oral sultamicillin. Causative pathogens were identified in six cases; all were susceptible to the combination of ampicillin and sulbactam. The mean duration of parenteral therapy was 7.1 days (6-11 days), and the average hospital stay was 10.3 days (6-18 days). Peak serum bactericidal titers of greater than or equal to 1:8 were achieved in all patients during parenteral therapy; only one child receiving oral therapy did not achieve a titer of greater than or equal to 1:4. At follow-up, all of the children were cured clinically and there was no evidence of relapse. Adverse reactions to oral therapy were minimal. The regimen of parenteral sulbactam/ampicillin and oral sultamicillin used sequentially is effective and safe for the treatment of skeletal infections in children. The use of this approach significantly reduced the duration of hospitalization.

Decreased baseline beta-lactamase production and inducibility associated with increased piperacillin susceptibility of Pseudomonas cepacia isolated from children with cystic fibrosis

The incidence of pulmonary infections in children with cystic fibrosis caused by Pseudomonas cepacia, an organism which may possess an inducible beta-lactamase, has increased since 1978. Seven of 13 sputum isolates of P. cepacia from children with cystic fibrosis were classified as inducible by quantitative enzyme production following preincubation with 100, 200, or 400 micrograms/ml of cefoxitin. The recovery of inducible strains tended to be associated with recent ceftazidime therapy. Susceptibility to aztreonam, ceftazidime, and piperacillin alone or combined with the beta-lactamase inhibitors. YTR 830 or sulbactam, and isoelectric focusing for beta-lactamase were performed. Inducible isolates produced significantly more beta-lactamase than noninducible strains with or without the addition of cefoxitin. Noninducible isolates were more susceptible than inducible isolates to 8 micrograms/ml of piperacillin, a difference that was eliminated with the addition of either beta-lactamase inhibitor. Twelve of 13 strains produced a beta-lactamase band in the pH range of 7.9-8.1; no differences in satellite patterns were noted between the two groups of organisms. Increased production of beta-lactamase in the absence of an inducer may account for piperacillin resistance in P. cepacia in children with cystic fibrosis.

Single-dose pharmacokinetics of aztreonam in children with cystic fibrosis

The single-dose pharmacokinetics of aztreonam was evaluated in 10 clinically stable subjects with cystic fibrosis. Each child received 30 mg aztreonam/kg intravenously over 2 to 3 minutes. Multiple timed blood samples were obtained over 8 hours for determination of aztreonam elimination kinetics; all urine excreted for 24 hours was collected in timed aliquots for the determination of aztreonam and its microbiologically inactive metabolite, SQ 26,992. Aztreonam pharmacokinetic parameters were determined by model-independent methods. Mean t1/2, steady-state volume distribution, and body clearance were 1.3 hr, 0.25 L/kg, and 127.2 ml/min/1.73m2, respectively. In 9 of the 10 subjects, two-compartment pharmacokinetic analysis was possible and compared favorably with model-independent parameter estimates. Twenty-four-hour urinary recovery of aztreonam was 76.3% of the administered dose; 2.6% was recovered as the metabolite SQ 26,992. The renal clearance of aztreonam averaged 92.5 ml/min/1.73m2. When these data are combined with in vitro susceptibility data for aztreonam against Pseudomonas aeruginosa isolated from the sputum of patients with cystic fibrosis, a dose of 200 mg aztreonam/kg/day divided six hourly would be predicted to maintain serum concentrations above the minimum inhibitory concentration (MIC) for these organisms for the majority of the dosing interval.

Comparative activities of the beta-lactamase inhibitors YTR 830, clavulanate and sulbactam combined with extended-spectrum penicillins against ticarcillin-resistant Enterobacteriaceae and pseudomonads

The in-vitro synergistic activity of YTR 830, a new beta-lactamase inhibitor, combined with four extended-spectrum penicillins (ticarcillin, piperacillin, mezlocillin and apalcillin) against ticarcillin-resistant clinical isolates of Gram-negative enteric bacilli was compared with that of clavulanate and sulbactam. Synergy testing was performed with fixed concentrations of beta-lactamase inhibitors (8 mg/l) combined with doubling dilutions of beta-lactams in microdilution trays. Synergy was defined as a four-fold or greater decrease of beta-lactam MIC in the combination compared with the beta-lactam alone. For 79 ticarcillin-resistant Enterobacteriaceae, ticarcillin-YTR 830 and ticarcillin-clavulanate were synergistic against 90% of strains; for ticarcillin-sulbactam, 70% showed synergy. The synergistic activity of all three inhibitors was similar against strains resistant only to ticarcillin; for strains resistant to all four extended-spectrum penicillins, the activity of ticarcillin with YTR 830 and clavulanate was similar (synergy against 79% of strains) and superior to ticarcillin-sulbactam (synergy against 39% of strains). YTR 830 was more active than clavulanate against Serratia, Citrobacter, Proteus and Providencia spp. Piperacillin, mezlocillin and apalcillin susceptible strains, with MICs of 8-16 mg/l, showed synergy with inhibitors against 37-87% of strains. Amongst pseudomonads, no synergy was demonstrated against Pseudomonas aeruginosa; ticarcillin produced synergy with the inhibitors against Ps. maltophilia, while piperacillin-YTR 830 and apalcillin-YTR 830 were synergistic against Ps. cepacia. YTR 830 appears to have comparable in-vitro activity to that of clavulanate, and further development of this compound is warranted.

Synergy of amoxycillin combined with clavulanate and YTR 830 in experimental infections in mice

YTR 830, a new beta-lactamase inhibitor, is synergistic with amoxycillin in vitro against a number of beta-lactamase-producing organisms. The combination of amoxycillin-YTR 830 was compared to amoxycillin-clavulanate in the treatment of experimental Staphylococcus aureus, Citrobacter freundii and Proteus mirabilis infections in mice. Both combinations were synergistic with amoxycillin against all three test organisms. The amoxycillin-clavulanate combination was superior against S. aureus and C. freundii while amoxycillin-YTR 830 was more effective against P. mirabilis. The difference in efficacy between the two drug combinations appears to relate to the degree of protection afforded the animals by the beta-lactamase inhibitor alone. YTR 830 is a promising new agent and should undergo further investigation.

Comparative activities of the beta-lactamase inhibitors YTR 830, clavulanate, and sulbactam combined with ampicillin and broad-spectrum penicillins against defined beta-lactamase-producing aerobic gram-negative bacilli

The in vitro synergistic activities of the beta-lactamase inhibitors YTR 830, clavulanate, and sulbactam, combined with ampicillin, ticarcillin, mezlocillin, azlocillin, piperacillin, and apalcillin, were determined against 34 strains of members of the Enterobacteriaceae family, Pseudomonas aeruginosa, Aeromonas hydrophila, and Haemophilus influenzae with characterized plasmid or chromosomal beta-lactamases or both. Strains were tested against fixed concentrations of beta-lactamase inhibitors (8 micrograms/ml) combined with doubling dilutions of beta-lactams. Synergy was defined as a fourfold or greater decrease in the MIC of the beta-lactam. Against Enterobacteriaceae producing Richmond and Sykes class III and V plasmid-mediated beta-lactamases, synergy was obtained against most strains with YTR 830- and clavulanate-beta-lactam combinations, with sulbactam being less effective. Against Enterobacteriaceae producing class I chromosomal beta-lactamases, combinations containing YTR 830 or sulbactam were more synergistic than combinations containing clavulanate. Against strains producing class V PSE enzymes, all three inhibitors were synergistic with piperacillin and apalcillin against strains producing PSE-1, -3, and -4 enzymes, while the PSE-2-producing strain was resistant to all inhibitors. YTR 830-beta-lactam combinations were also synergistic against strains producing the novel beta-lactamases OHIO-1, TLE-1, AER-1, and ROB-1. Overall, YTR 830 with piperacillin or apalcillin was the most effective combination.

Clinical presentation and management of Pseudomonas osteomyelitis

To determine the incidence and clinical characteristics of Pseudomonas aeruginosa osteomyelitis in children, the records of 144 hospitalized patients under 19 years of age were reviewed; 104 fulfilled the study criteria for the diagnosis of acute or chronic osteomyelitis. Pseudomonas aeruginosa was recovered from 10.6 percent of the children and was the second most common pathogen isolated. In comparison to children with staphylococcal infections, patients with pseudomonal osteomyelitis were significantly older, gave an antecedent history of penetrating trauma, and lacked clinical and laboratory evidence of systemic illness. The data collected in this study suggest that osteomyelitis due to Pseudomonas aeruginosa is a distinct entity with clinical features differing from those of Staphylococcus aureus. Management should be directed at adequate surgical debridement followed by 10 to 21 days of antimicrobial therapy.

Hemophilus influenzae type f meningitis in an adolescent

A 17-year-old male with Hemophilus influenzae type f meningitis is reported. Recent studies which suggest that the incidence of H. influenzae meningitis in older individuals is increasing are reviewed. Therefore, we recommend that antimicrobial therapy directed against H. influenzae be included in the initial management of older children, adolescents, and adults with acute bacterial meningitis.

In-vitro activity of ciprofloxacin and other antibacterial agents against Pseudomonas aeruginosa and Pseudomonas cepacia from cystic fibrosis patients

The in-vitro activities of ciprofloxacin, a new oxyquinoline derivative, norfloxacin and six anti-pseudomal beta-lactam antibiotics were tested against pulmonary isolates of smooth and mucoid colony forms of Pseudomonas aeruginosa, and Ps. cepacia from children with cystic fibrosis. Ciprofloxacin was the most effective of the agents tested against either species. Minimal inhibitory concentrations of ciprofloxacin were 0.5, and 16 mg/l, for 90% of the Ps. aeruginosa and Ps. cepacia strains tested, respectively. No effect of inoculum size or discordance between inhibitory or bactericidal concentrations was observed. Ciprofloxacin is a potentially useful agent for the treatment of acute pseudomonal pulmonary exacerbations in children with cystic fibrosis.

Comparison of cefpiramide (HR-810) and four anti-pseudomonal beta-lactam agents against pseudomonas isolates from children with cystic fibrosis

Cefpiramide (HR-810), ceftazidime, piperacillin, ticarcillin, and aztreonam were tested against tobramycin-sensitive and -resistant strains of Pseudomonas aeruginosa and tobramycin/amikacin-resistant isolates of Ps. cepacia recovered from the sputum of patients with cystic fibrosis. Against Ps. aeruginosa, none of the drugs inhibited 90% of the test strains at levels of less than 128 mg/l. Median minimal, inhibitory concentrations (MIC50) for all of the beta-lactam agents were lower for tobramycin-sensitive versus tobramycin-resistant isolates of Ps. aeruginosa. Ceftazidime was the most effective agent against Ps. cepacia. Aminoglycoside-resistance appears to be associated with significant beta-lactam resistance in Ps. aeruginosa isolated from the sputum of patients with cystic fibrosis.

Pharmacokinetics and cerebrospinal fluid penetration of ceftazidime in children with meningitis

The single dose pharmacokinetics and cerebrospinal fluid (CSF) penetration of ceftazidime were determined in 10 children with bacterial meningitis. Serum ceftazidime pharmacokinetics showed a distinct age dependence in which the clearance in children less than 1 month of age was markedly reduced. Ceftazidime concentrations in CSF, which ranged from 1.4-8.5 micrograms/ml, exceeded the minimum bactericidal concentrations for infecting pathogens throughout the 8-hour sampling period. These concentrations were found to be independent of CSF cell count, protein concentration or the day of therapy on which the study was performed. The ratio of CSF to serum ceftazidime concentration increased with time, suggesting that ceftazidime was cleared more slowly from CSF than from peripheral blood. Our data support the initiation of a study comparing the efficacy of ceftazidime to conventional therapy in children with bacterial meningitis.

Comparative activities of the beta-lactamase inhibitors YTR 830, sodium clavulanate, and sulbactam combined with amoxicillin or ampicillin

YTR 830, a new beta-lactamase inhibitor, was compared with clavulanic acid and sulbactam against aminopenicillin-resistant clinical isolates. At a concentration of 8 micrograms/ml, YTR 830 was as effective as clavulanate or sulbactam in reducing the aminopenicillin MICs. Combined with amoxicillin, YTR 830 is a potentially useful agent for therapy of many bacterial infections.

Ceftazidime as initial therapy for suspected bacterial infections in hospitalized pediatric patients

Ceftazidime, a new beta-lactam antibiotic, was used to treat 60 children with suspected bacterial infections occurring outside the central nervous system. The patients ranged in age from 0.1 to 21 years and received 30 mg of ceftazidime per kg up to a total single dose of 1 g administered every 8 h. Fifty-three pathogens were isolated from 43 children before the initiation of therapy. All children responded clinically, although one child failed bacteriologically and five children were considered colonized at the end of ceftazidime therapy. Adverse reactions associated with ceftazidime administration were primarily alterations in laboratory parameters and were clinically insignificant. Ceftazidime administered on an 8-h dosing regimen is effective monotherapy for the treatment of childhood infections.

Moxalactam therapy of serious pediatric infections

Forty children with documented or suspected bacterial infections arising outside the central nervous system (CNS) were studied. Fifteen different pathogens for a total of 30 isolates were obtained from multiple sources. Staphylococcus aureus (minimum inhibitory concentrations 4-8 micrograms/ml) was the most common pathogen isolated, involving seven patients. Each patient received moxalactam 50 mg/kg iv over 15 minutes q8h and responded favorably to therapy, exhibiting bacteriologic and/or clinical cures. Toxicity associated with moxalactam occurred in only two patients and necessitated discontinuation of drug therapy. Moxalactam 50 mg/kg iv q8h is effective therapy for non-CNS infections occurring in infants and children.

A double-blinded comparative study of sultamicillin and potassium penicillin V in the treatment of childhood streptococcal pharyngitis

Fifty-two children with positive pharyngeal cultures for group A streptococci were randomized to receive phenoxymethyl penicillin or sultamicillin, an ester of ampicillin and sulbactam. By serological and bacteriological criteria, sultamicillin was effective in 100% of the 20 evaluable cases of infection and carriage while penicillin was effective in six out of eight (75%) and three out of eight (93%) respectively. Of the eight children with infections treated with sultamicillin, three (37.5%) became recolonized with the organism compared to none of the children in the penicillin group. These differences were not statistically significant.

In vitro activities of aztreonam, piperacillin, and ticarcillin combined with amikacin against amikacin-resistant Pseudomonas aeruginosa and P. cepacia isolates from children with cystic fibrosis

Amikacin, combined with aztreonam, piperacillin, or ticarcillin, synergistically inhibited amikacin-resistant sputum isolates of Pseudomonas aeruginosa and P. cepacia from children with cystic fibrosis. Ticarcillin-amikacin was the least active combination. Aminoglycoside resistance should not preclude the use of beta-lactam-aminoglycoside combinations in the treatment of pulmonary infections in cystic fibrosis.

Comparison of the efficacy and safety of ceftriaxone to ampicillin/chloramphenicol in the treatment of childhood meningitis

Ceftriaxone is a new cephalosporin with a broad spectrum of antibacterial activity and unique serum and CSF pharmacokinetics. The drug was compared in a randomized fashion with ampicillin and chloramphenicol in the treatment of 19 children with Haemophilus influenzae type b meningitis. Ceftriaxone was also administered non-randomly to six other patients including three children with Gram-negative meningitis. Among the children with H. influenzae meningitis, no deaths were noted and the outcomes of the study and the control groups were similar. Ninety per cent of the isolates of H. influenzae were inhibited by 0.0625, 1 and 1 mg/l of ceftriaxone, ampicillin and chloramphenicol respectively. One child with pneumococcal meningitis and two children with meningococcal meningitis recovered rapidly and without incident during ceftriaxone therapy. Three children with Gram-negative meningitis caused by multiply-drug resistant organisms were bacteriologically cured within five days of the onset of therapy. Persistent pleocytosis and neurological disabilities were noted in two at the conclusion of therapy. Ceftriaxone, as a single agent, was comparable in efficacy with traditional antimicrobial therapy usually employed in childhood meningitis.

Evaluation of latamoxef as initial therapy of bone and joint infections in childhood

The efficacy and pharmacokinetics of latamoxef were evaluated during initial therapy of bacteriologically proven bone and joint infections in children. Pharmacokinetic evaluation revealed no significant difference in latamoxef biodisposition after the first dose or at steady state. Peak serum concentrations exceeded 140 mg/l and 8-hour trough concentrations averaged 6.5 mg/l. The patients were infected with a variety of gram-positive and gram-negative pathogens. All were sensitive to readily achievable serum concentrations of latamoxef; moreover, the serum concentration remained above the MIC of the most resistant organism for at least 7 h after each dose. All patients responded favorably to initial therapy and there have been no relapses in more than 2 years of clinical follow-up.

Single-dose plasma and cerebrospinal fluid pharmacokinetics of ceftriaxone in infants and children

Pharmacokinetic variables were studied in children with central nervous system infections who received a single dose of ceftriaxone sodium. After initial lumbar puncture of children with documented or suspected bacterial meningitis, ventriculitis, or both, therapy was initiated with i.v. ampicillin and chloramphenicol. Children were randomly selected to receive a single i.v. dose of ceftriaxone. Concentrations of ceftriaxone were measured in plasma at intervals from 0 to 720 minutes after the beginning of the infusion and in cerebrospinal fluid (CSF) at one to five hours after the dose. Blood samples were obtained immediately after the second lumbar puncture for assessment of drug penetration into CSF. Elimination rate constant, elimination half-life, apparent volume of distribution, and plasma clearance were determined from samples obtained 30-720 minutes after the start of the infusion. In two children with ventriculoperitoneal shunts, serial determinations of ceftriaxone in CSF were obtained. All eight children who received 75 mg/kg and five of eight who received 50 mg/kg had positive CSF cultures. Volume of distribution was less after the 50 mg/kg dose than after the 75 mg/kg dose. In the children with shunts, adequate CSF drug concentrations were maintained throughout 12 hours of testing. These data support a 12-hour dosage interval, but clinical studies are needed to evaluate efficacy of the drug at both 12-hour and 24-hour dosage regimens.

Efficacy and safety of ceftriaxone in serious pediatric infections

Thirty-four patients aged 1 month to 19 years were treated with ceftriaxone for suspected bacterial infections. Bacterial pathogens were isolated from 25 children. The overall bacterial cure rate was 88%, with an overall clinical response rate of 96%. No side effects requiring cessation of therapy were observed. Ceftriaxone proved to be safe and effective in the treatment of serious infections in children.

Developmental pharmacokinetics of moxalactam

A pharmacokinetic evaluation of moxalactam was performed with 30 infants and children with documented or suspected bacterial infections arising outside the central nervous system. Each child received 50 mg of moxalactam per kg infused intravenously over a period of 15 min every 8 h. A total of 26 children were studied after receiving the first dose; 20 of these, along with 4 additional patients, were evaluated after receiving continuous therapy for at least 3 days. After the first dose, the elimination half-life, apparent volume of distribution, and plasma clearance averaged 1.59 h, 0.331 liter/kg, and 100.9 ml/min per 1.73 m2, respectively. The biodisposition of the moxalactam epimers was also evaluated, with similar overall results. No differences in pharmacokinetic parameters were observed when the first-dose values were compared with those obtained at the steady state. Age-dependent changes in moxalactam elimination were observed for children of less than or equal to 1 year of age, suggesting that a dosage reduction may be necessary for children of less than or equal to 2 months of age.