Antimicrobial survey of urinary tract isolates from a pediatric department

Incidence of Breakthrough Urinary Tract Infection in Hospitalized Infants Receiving Antibiotic Prophylaxis

Urinary tract infections (UTIs) are a source of substantial morbidity in children in the neonatal intensive care unit. The incidence of UTIs that occur in critically ill infants during a course of antibiotic prophylaxis (i.e., breakthrough urinary tract infections [BUTIs]) is not known. We investigated the incidence of BUTI in a cohort of infants hospitalized on prophylactic antibiotics in neonatal intensive care units. Predictors of BUTI were evaluated using multivariable Cox regression. Out of 716 787 infants, 631 (0.09%) were prescribed 821 courses of antibiotic prophylaxis. Among this cohort, 60 infants (9.5%) suffered a total of 65 BUTIs. Of all prophylactic antibiotic courses, 65/821 (7.9%) were complicated by BUTI. Klebsiella, Enterobacter, and Escherichia coli species were the most common causes of BUTI. There was no statistically significant difference ( P = .78) in BUTI incidence among the 4 antibiotics assessed (amoxicillin, cephalexin, nitrofurantoin, or trimethoprim-sulfamethoxazole).

Febrile urinary tract infection in children: ampicillin and trimethoprim insufficient as empirical mono-therapy

The aim of this study was to characterize the pathogens and their antibiotic susceptibilities in defined groups of children (total number 694) with urinary tract infection (UTI) regarding age, first UTI (FUTI) or recurrent UTI (RUTI), renal abnormalities or vesico-ureteric reflux (VUR) in order to optimize empirical antibiotic therapy and prophylaxis. In patients aged between 1 month and 24 months with a first febrile UTI (FUTI; n = 205) the leading pathogen was Escherichia coli (E. coli) (83.4%). In comparison with patients with FUTI, those with RUTI (n = 24) had more Enterococcus and Enterobacter infections and higher resistance rates of E. coli against trimethoprim (TMP), trimethoprim/sulfamethoxazole (SXT) or ampicillin (AMP). Boys with ultrasound-detected renal abnormalities (n = 71) showed 14.2% Pseudomonas and 59.1% E. coli infections versus girls (n = 48) (2.1% Pseudomonas and 93.7% E. coli). Of 390 patients who underwent voiding cysto-urethrography, 31.5% had VUR. Of them, 45.5% received antimicrobial prophylaxis with SXT (n = 30) or cefazolin (n = 26). There was no difference between girls (n = 242) and boys (n = 148) regarding the frequency of VUR and pathogens. There were more TMP- and SXT-resistant E. coli cultures from patients with VUR (37.8%) than from those without VUR (25.8%). Treatment with TMP, SXT and AMP alone appeared to be insufficient in many cases because of high resistance rates of E. coli and other uropathogens.

Multidrug resistance in pediatric urinary tract infections

Urinary tract infections (UTIs) represent a common infection in the pediatric population. Escherichia coli is the most common uropathogen in children, and antimicrobial resistance in this species complicates the treatment of pediatric UTIs. Despite the impact of resistance on empiric antibiotic choice, there is little data on multidrug resistance in pediatric patients. In this paper, we describe characteristics of multidrug-resistant E. coli in pediatric patients using a large national database of uropathogens antimicrobial sensitivities. Antimicrobial susceptibility patterns to commonly prescribed antibiotics were performed on uropathogens isolated from children presenting to participating hospitals between 1999 and 2001. Data were analyzed separately for four pediatric age groups. Single and multidrug resistance to ampicillin, amoxicillin-clavulanate, cefazolin, ciprofloxacin, nitrofurantoin, and trimethoprim-sulfamethoxazole (TMP-SMX) were performed on all specimens. There were a total of 11,341 E. coli urine cultures from 343 infants (0-4 weeks), 1,801 toddlers (5 weeks-24 months), 6,742 preteens (2-12 years), and 2,455 teens (13-17 years). E. coli resistance to ampicillin peaked in toddlers (52.8%) but was high in preteens (52.1%), infants (50.4%), and teens (40.6%). Resistance to two or more antibiotics varied across age groups, with toddlers (27%) leading preteens (23.1%), infants (21%), and teens (15.9%). Resistance to three or more antibiotics was low in all age groups (range 3.1-5.2%). The most common co-resistance in all age groups was ampicillin/TMP-SMZ. In conclusion, less than half of all pediatric UTIs are susceptible to all commonly used antibiotics. In some age groups, there is a significant percentage of co-resistance between the two most commonly used antibiotics (ampicillin and TMP-SMZ).

Antibiotic resistance trends in paediatric uropathogens

The antimicrobial susceptibility patterns of paediatric uropathogens to six of the most common antibiotics in use for urinary tract infections were determined. The bacterial isolates came from the urine of children presenting as outpatients to participating US hospitals between April 2002 and May 2004. Strains of the six most common uropathogens were included in the analysis. Results were stratified by paediatric age group. In total, 11174 female and 1557 male positive cultures were analysed. The overall resistance rates for females and males, respectively, were as follows: ampicillin 44.3% and 44.6%; sulphamethoxazole/trimethoprim 24.5% and 36.7%; amoxicillin/clavulanic acid 12.4% and 27.5%; cefazolin 10.9% and 27.1%; ciprofloxacin 0.9% and 2.4%; and nitrofurantoin 4.4% and 11.0%. Uropathogen resistance to commonly used antibiotics in the paediatric population was high.

Antibiotic resistance patterns of uropathogens in pediatric emergency department patients

OBJECTIVES

To evaluate the prevalence of resistance of the various urinary tract infection (UTI) pathogens obtained from patients in an urban pediatric emergency department (PED), and to identify risk factors for infection with resistant strains.

METHODS

The data were collected retrospectively in an urban, academic PED in northeastern Florida. The microbiology-computerized database was used to identify all positive urine cultures from October 1999 through June 2000. All patients aged 17 years or less, whose urine specimen was collected in the ED and grew cultures with greater than 10,000 colony forming units (CFU) per milliliter of a single organism on Maconkey or blood agar, were included. The medical records of the patients were reviewed and selective demographic and clinical data were collected. Patients were excluded if their charts were unavailable for review or if the pathogen that grew in culture was a suspected contaminant. All patients lacking clinical symptoms of UTI (frequency, dysuria, abdominal pain, fever, or urgency) and whose urine was collected by clean-catch were excluded if their culture grew between 10,000 and 100,000 CFU. Resistance to trimethoprim-sulfamethoxazole (T-S) was estimated for the subset of gram-negative pathogens. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to compare rates of resistance among patients with and without the following risk factors: age greater than 4 years; current or recent antibiotic use; day care attendance; and previous UTI.

RESULTS

A total of 126 urine cultures were identified for inclusion. Of these, 45 patients were excluded, leaving 81 who met the study criteria. The majority of isolated organisms were Escherichia coli, accounting for 89% of the patients (n = 72). Other organisms identified were Klebsiella 3.7%, Proteus 1.2%, Citrobacter 1.2%, Staphylococcus 1.2%, and Enterococcus 3.7% (all in children < 4 years old). The resistance to T-S was 6.5% (95% CI = 0.9% to 12.1%) for gram-negative pathogens. Overall, 48% of gram-negative isolates were resistant to one or more antibiotics, any resistance (95% CI = 36.5% to 59.5%). T-S resistance was nominally higher for older children and for those with a history of antibiotic use, although not to a significant degree. Children less than age 4 were more likely to have any resistance (OR 2.6; 95% CI = 1.0 to 6.7).

CONCLUSIONS

The resistance to T-S in this study was 6.7% for gram-negative pathogens. These rates are lower than rates reported in adult populations, international pediatric studies, and the authors' hospital antibiograms, demonstrating the importance of local, population-specific data in selecting antibiotics. This study did not identify any statistically significant risk factors for resistance to T-S, but suggests that those with a recent history of antibiotic use may be at highest risk. While children less than 4 years old with gram-negative pathogens have nominally lower rates of T-S resistance, they are at higher risk for resistance to one or more antibiotics (any resistance) and are at risk for UTI caused by enterococcus (uniformly nonsusceptible to T-S). Prospective studies are needed to validate these results and to identify predisposing factors for urinary pathogens with antibiotic resistance.

[Urinary antimicrobial prophylaxis]

Antibiotics are usually used to prevent childhood recurrent urinary tract infections: cystitis or pyelonephritis. The mechanism of action of these antibiotics, although imperfectly known, seems to be double: the antibiotic acts by its bactericidal effect, but also probably for minimal concentrations by reducing adhesion capability of bacteria to the urothelium. The most commonly used molecules are cotrimoxazole, trimethoprime, pivmecillinam, cefaclor and nalidixic acid. However all have not been studied rigorously as for their prophylactic capacity, and in particular very little is known for patients presenting with vesico-ureteral reflux.

Cefixime in urinary tract infections with special reference to pediatrics: overview

Cefixime is a third-generation oral cephalosporin that is highly active against a broad range of gram-negative and some gram-positive aerobic bacteria. In non-complicated urinary tract infections it is at least as effective as other usual treatments, and has a low rate of side effects. Several clinical studies have been performed on cefixime in urinary tract infections both in adults and children. On the basis of the literature data, cefixime could be indicated in the treatment of non-complicated urinary tract infections in children either as monotherapy or as switch therapy.

Amphotericin B-induced nephrotoxicity: a review

Amphotericin B is the gold standard for antifungal treatment for the most severe mycoses. However, adverse effects are common, with nephrotoxicity being the most serious, occurring early in the course of treatment, and usually being reversible in most patients. Tubular damage is a well known problem associated with amphotericin B therapy but acute renal failure is the most serious complication. Recent studies have examined ways to ameliorate the well-known toxicities of amphotericin B. A new approach has been to complex the drug with lipids or entrap it in liposomes. This review will concern amphotericin B-induced nephrotoxicity, whose mechanisms are not completely clear. Nephrotoxicity seems related to direct amphotericin B action on the renal tubules as well as to drug-induced renal vasoconstriction. The main mechanisms of nephrotoxicity suggested in the literature are presented. The clinical picture at different ages (adults, children, newborns), interactions of clinical significance, strategies for prevention of amphotericin B-induced nephrotoxicity are summarized. To provide optimal patient care, it is imperative that the clinician understand the etiology of and the signs and symptoms associated with nephrotoxicity, as well as interventions to prevent nephrotoxicity in patients receiving amphotericin B.

Fluoroquinolones in pediatrics and their nephrotoxicity in adults: minireview

In recent years there is increasing pressure to use fluoroquinolones in pediatric patients but relatively few data have been published in the literature. Therefore this paper reviews the available information about the pharmacokinetics of fluoroquinolones in children and their use in pediatric urinary tract infections, taking into account their potential as nephrotoxic agents. From the available data it seems reasonable to suggest that there is no risk of quinolone-induced nephrotoxicity and that this class of antibiotics may therefore be considered as potential candidates in urinary tract infections in children. Nevertheless adequate pharmacokinetic investigations and further studies on long-term monitoring for potential toxicity need to be conducted in pediatric populations.

Antibiotic prophylaxis in children with relapsing urinary tract infections: review

Recurrent urinary tract infections (UTIs) are observed in 30-50% of children after the first UTI. Of these, approximately 90% occur within 3 months of the initial episode. The basic aim of antibiotic prophylaxis in children with malformative uropathy and/or recurrent UTIs, is to reduce the frequency of UTIs. The bacteria most frequently responsible for UTI are gram-negative organisms, with Escherichia coli accounting for 80% of urinary tract pathogens. In children with recurrent UTIs and in those treated with antibiotic prophylaxis there is a greater incidence of UTI due to Proteus spp., Klebsiella spp. and Enterobacter spp., whereas Pseudomonas spp., Serratia spp. and Candida spp. are more frequent in children with urogenital abnormalities and/or undergoing invasive instrumental investigations. Several factors are involved in the pathogenesis of UTI, the main ones being circumcision, periurethral flora, micturition disorders, bowel disorders, local factors and hygienic measures. Several factors facilitate UTI relapse: malformative uropathies, particularly of the obstructive type; vesico-ureteric reflux (VUR); previous repeated episodes of cystitis and/or pyelonephritis (3 or more episodes a year), even in the absence of urinary tract abnormalities; a frequently catheterized neurogenic bladder; kidney transplant. The precise mechanism of action of low-dose antibiotics is not yet fully known. The characteristics of the ideal prophylactic agent are presented in this review, as well as indications, dosages, side effects, clinical data of all molecules. While inappropriate use of antibiotic prophylaxis encourages the emergence of microbial resistance, its proper use may be of great value in clinical practice, by reducing the frequency and clinical expression of UTIs and, in some cases such as VUR, significantly helping to resolve the underlying pathology.