Quality of care among Aboriginal hemodialysis patients

Registry data report racial differences in hemodialysis (HD) care, with ethnic minorities at a disadvantage. However, little information is available regarding Aboriginal HD patients specifically. This study sought to compare the quality of HD care between Aboriginal and non-Aboriginal patients in Canada. All adults who were established on HD for > or = 6 mo in a single Canadian province were included. Clinical information was obtained by patient interview and chart review, with race determined by self-report. Quality of HD care was assessed by small solute clearance, BP control, mineral metabolism, and anemia management. Of the 835 patients, 95 (11.4%) were Aboriginal. Aboriginal patients were significantly younger, were more likely to have diabetes as the cause of ESRD, and had a higher degree of comorbidity than non-Aboriginal patients. There were no differences between Aboriginal and non-Aboriginal patients for small solute clearance, anemia management, or use of permanent vascular access. Aboriginal patients, however, were less likely to achieve a target predialysis systolic BP of < 140 mmHg (29.5 versus 44.9%; P = 0.004), a target phosphate level of < 1.8 mmol/L (40.0 versus 67.3%; P < 0.0001), and a calcium-phosphate product < 4.4 mmol2/L2 (52.6 versus 72.7%; P < 0.001). Quality of care was found to be similar for Aboriginal compared with non-Aboriginal HD patients except for differences in predialysis systolic BP and mineral metabolism, which may be influenced by individual and cultural factors. Explanations for these differences and their impact on morbidity and mortality warrant further investigation.

Acute Otitis Media Due to Penicillin-Nonsusceptible Streptococcus pneumoniae Before and After the Introduction of the Pneumococcal Conjugate Vaccine

BACKGROUND

The impact of the 7-valent pneumococcal conjugate vaccine (PCV7 [Prevnar]) on penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) recovered from children with acute otitis media (AOM) is unclear.

METHODS

At 5 hospitals, 505 pneumococcal isolates were collected from children with AOM between 1 January 1999 and 31 December 2002. Molecular subtyping was performed on 158 isolates.

RESULTS

Overall, the percentage of AOM cases due to non-PCV7 serogroups (including serotype 3) increased over time (from 12% in 1999 to 32% in 2002; P < .01) and according to the number of PCV7 doses received (18% [< or = 1 dose] vs. 35% [2-4 doses]; P < .01). The percentage of cases due to vaccine-related serotypes (including serotype 19A) increased according to the number of PCV7 doses received (10% [< or = 1 dose] vs. 19% [2-4 doses]; P = .05) but not over time, whereas the percentage of cases due to serotype 19F remained unchanged both over time and according to the number of PCV7 doses received. The frequency of penicillin nonsusceptibility among PCV7 serotypes (range, 65%-75%) and non-PCV7 serogroups (range, 11%-27%) did not significantly change overall. Although no change was detected among isolates collected from children with spontaneous drainage, the percentage of pneumococci recovered at the time of myringotomy and/or tympanostomy tube placement that were nonresistant to penicillin decreased over time (from 73% in 1999 to 53% in 2002; P = .03). All of the serotype 3 strains were genetically related, whereas 88% of the isolates that were either serotype 19F or serotype 23F were related to 1 of 3 international clones.

CONCLUSIONS

Among children with AOM, the proportion of cases due to non-PCV7 serogroups increased, vaccine-related serotypes increased, and serotype 19F remained unchanged. Although a decrease in the proportion of cases due to PNSP occurred among children who required myringotomy and/or tympanostomy tube placement, the proportion of PNSP remained unchanged overall and among children with spontaneous drainage. Because future trends in the susceptibility patterns of pneumococcal isolates recovered from children with AOM are not easy to predict, continued surveillance is essential.

Guidelines for the selection of antibacterial therapy in children

This article reviews factors important in the selection of antimicrobial agents in infants and children. Recommendations for antibiotic therapy for a wide range of infections occurring in children are provided.

Pharmacokinetics of gatifloxacin in infants and children

Gatifloxacin is an 8-methoxy fluoroquinolone effective against a broad spectrum of pathogens common in pediatric infections. The safety and pharmacokinetics of a single dose of gatifloxacin were studied in pediatric patients from 6 months to 16 years of age. Seventy-six pediatric patients (average age, 6.7 +/- 5.0 years) were administered a single oral dose of gatifloxacin suspension (5, 10, or 15 mg/kg of body weight; 600-mg maximum) in a dose-escalating manner. Subjects were stratified by age into 4 groups. An additional 12 children, greater than 6 years of age, received gatifloxacin as the tablet formulation at a dose of approximately 10 mg/kg. Gatifloxacin's apparent clearance and half-life were 5.5 +/- 2.1 ml/min/kg and 5.1 +/- 1.4 h. The maximum concentration of drug in plasma and area under the concentration-time curve (AUC) increased in a manner approximately proportional to the dose. At the 10-mg/kg dose, the bioavailability was similar between the suspension and tablet formulation. The apparent oral clearance of gatifloxacin, normalized for body weight, exhibited a small but statistically significant decrease with increasing age. In all subjects receiving gatifloxacin at 10 mg/kg, the AUC exceeded 20 microg . h/ml (estimated free AUC/MIC ratio of > or =34 for MIC of < or =0.5 microg/ml). These data suggest that gatifloxacin at a dose of 10 mg/kg every 24 h will achieve therapeutic concentrations in plasma in infants and children.

Defining pneumonia in critically ill infants and children

OBJECTIVE

To define pneumonia in critically ill children in the intensive care unit setting for surveillance of infection and for the design, conduct, and evaluation of clinical trials in the prevention and therapy of lower respiratory tract infections in this population.

DESIGN

Summary of the literature with review and consensus by experts in the field.

RESULTS

A variety of diagnostic criteria from the medical literature, professional societies, and governmental health agencies and regulators were identified. Very few of these diagnostic criteria have been validated for use in children. We propose definitions for definite, possible, and probable pneumonia that build on identified definitions in the literature and use combinations of symptoms, signs, and laboratory criteria. Gaps in knowledge were identified.

CONCLUSIONS

Although pneumonia is one of the most common diagnoses in critically ill children, there have been few studies validating diagnostic criteria. Definitions for definite, probable, and possible community-acquired pneumonia and nosocomial pneumonia were achieved by consensus of experts based on guidelines from governmental agencies, professional organizations, and published literature. Future research should determine the utility of these definitions in the critically ill child and adapt them accordingly.

Prediction of neurologic sequelae in childhood tuberculous meningitis: a review of 20 cases and proposal of a novel scoring system

BACKGROUND

Despite effective antituberculous medications, the mortality and morbidity remain high in children with tuberculous meningitis (TBM). The traditional clinical staging for TBM developed by Lincoln et al in 1960 has been widely used to predict long term neurologic sequelae (NS). In the current era of critical care medicine and corticosteroid therapy, a new scoring system is needed to predict NS more accurately in children with TBM.

METHODS

We reviewed all available cases of TBM in San Diego, CA, during 1991-2001 retrospectively, and we developed a novel scoring system to predict NS in children with TBM. We assessed a tuberculous meningitis acute neurologic (TBAN) score at day 0 and on day 3 of hospitalization, to compare children who subsequently developed severe NS with those who did not.

RESULTS

Among 20 children with TBM, 7 children developed severe NS and 1 child died during hospitalization. The TBAN score was higher on day 0 in those with severe NS (5.5 versus 2.0, P = 0.09), and the difference became statistically significant by day 3 of hospitalization (5.5 versus 0.0, P = 0.02). Sensitivity and specificity of the TBAN score (> or =4) on day 0 (75 and 92%) and day 3 (88 and 100%) to predict severe NS were superior to the traditional clinical staging system on day 0 (63 and 58%).

CONCLUSIONS

The TBAN score is an objective marker for predicting severe NS in children with TBM.

Using listening difficulty ratings of conditions for speech communication in rooms

The use of listening difficulty ratings of speech communication in rooms is explored because, in common situations, word recognition scores do not discriminate well among conditions that are near to acceptable. In particular, the benefits of early reflections of speech sounds on listening difficulty were investigated and compared to the known benefits to word intelligibility scores. Listening tests were used to assess word intelligibility and perceived listening difficulty of speech in simulated sound fields. The experiments were conducted in three types of sound fields with constant levels of ambient noise: only direct sound, direct sound with early reflections, and direct sound with early reflections and reverberation. The results demonstrate that (1) listening difficulty can better discriminate among these conditions than can word recognition scores; (2) added early reflections increase the effective signal-to-noise ratio equivalent to the added energy in the conditions without reverberation; (3) the benefit of early reflections on difficulty scores is greater than expected from the simple increase in early arriving speech energy with reverberation; (4) word intelligibility tests are most appropriate for conditions with signal-to-noise (S/N) ratios less than 0 dBA, and where S/N is between 0 and 15-dBA S/N, listening difficulty is a more appropriate evaluation tool.

Newer antistaphylococcal agents

PURPOSE OF REVIEW

As antibiotic resistance in staphylococci continues to evolve, the ability to treat infections in children with confidence using first-generation cephalosporins, penicillins, and macrolides is decreasing. Knowledge of the local trends in resistance is important in making decisions of empiric antibiotic therapy. The antibiotic resistance pattern for the child's pathogen should be assessed whenever possible, to allow the practitioner to properly judge the risks and benefits of alternative antibiotic agents, should they be required for definitive therapy.

RECENT FINDINGS

Options for therapy of most methicillin-resistant and macrolide-resistant community-acquired strains of Staphylococcus aureus include vancomycin, linezolid, and, in communities with a high proportion of susceptible strains, clindamycin. Daptomycin, a lipopeptide antibiotic with activity against virtually all strains of S. aureus, was recently approved by the United States Food and Drug Administration for adults. Second-generation glycopeptide antibiotics similar to vancomycin are in clinical trials in adults, including dalbavancin and oritavancin. Several new compounds, including cephalosporins active against methicillin-resistant S. aureus, are in preclinical development as well.

SUMMARY

The recent worldwide emergence and rapid spread of community-acquired methicillin-resistant S. aureus has prompted a change in the approach to therapy of staphylococcal infections in both the outpatient clinic and the hospital. Newer agents active against methicillin-resistant S. aureus such as linezolid have been recently approved for children and other agents recently approved for adults are under investigation in children. Older agents for which relatively few data from prospective, controlled, comparative studies exist in the treatment of staphylococcal infections may also offer effective and less costly options for therapy.

General method of preparation of mesoporous M/Si3N4 nano-composites via a non-aqueous sol–gel route

We report a general method for the preparation of transition-metal silicon nitride nanocomposites; for example, mesoporous Pd-Si3N4 nanocomposite materials with high surface area were prepared by pyrolysis of a silicon palladium imide-chloride complex which was synthesized by reaction of silicon diimide gel with palladium chloride. These porous nanocomposites catalyse organic reactions.

Measures for assessing architectural speech security (privacy) of closed offices and meeting rooms

Objective measures were investigated as predictors of the speech security of closed offices and rooms. A new signal-to-noise type measure is shown to be a superior indicator for security than existing measures such as the Articulation Index, the Speech Intelligibility Index, the ratio of the loudness of speech to that of noise, and the A-weighted level difference of speech and noise. This new measure is a weighted sum of clipped one-third-octave-band signal-to-noise ratios; various weightings and clipping levels are explored. Listening tests had 19 subjects rate the audibility and intelligibility of 500 English sentences, filtered to simulate transmission through various wall constructions, and presented along with background noise. The results of the tests indicate that the new measure is highly correlated with sentence intelligibility scores and also with three security thresholds: the threshold of intelligibility (below which speech is unintelligible), the threshold of cadence (below which the cadence of speech is inaudible), and the threshold of audibility (below which speech is inaudible). The ratio of the loudness of speech to that of noise, and simple A-weighted level differences are both shown to be well correlated with these latter two thresholds (cadence and audibility), but not well correlated with intelligibility.

Acute disseminated encephalomyelitis in childhood: epidemiologic, clinical and laboratory features

BACKGROUND

Acute disseminated encephalomyelitis (ADEM) is a central nervous system demyelinating disease that usually follows an apparently benign infection in otherwise healthy young persons. The epidemiology, infectious antecedents and pathogenesis of ADEM are poorly characterized, and some ADEM patients are subsequently diagnosed with multiple sclerosis (MS).

METHODS

We retrospectively (1991-1998) and prospectively (1998-2000) studied all persons aged < 20 years diagnosed with ADEM from the 3 principal pediatric hospitals in San Diego County, CA, during 1991-2000. Acute neurologic abnormalities and imaging evidence of demyelination were required for study inclusion. Epidemiologic variables, risk factors, clinical course, laboratory and radiographic findings, neuropathology and treatment data were analyzed. Interleukin (IL)-12, interferon-gamma (IFN-gamma) and IL-10 were assayed in blinded manner on cerebrospinal fluid (CSF) obtained prospectively from a subset of ADEM cases and compared with CSF from patients with enteroviral (EV) meningoencephalitis confirmed by polymerase chain reaction (PCR) and controls without pleocytosis.

RESULTS

Data were analyzed on 42 children and adolescents diagnosed with ADEM during 1991-2000, and CSF IL-12, IFN-gamma and IL-10 levels were compared among ADEM (n = 14), EV meningoencephalitis (n = 14) and controls without pleocytosis (n = 28). Overall incidence of ADEM was 0.4/100,000/year; incidence quadrupled during 1998-2000 compared with earlier years. No gender, age stratum, ethnic group or geographic area was disproportionately affected. A total of 4 (9.5%) patients initially diagnosed with ADEM were subsequently diagnosed with MS after multiple episodes of demyelination. Although most children eventually recovered, 2 died, including 1 of the 3 ultimately diagnosed with MS. Magnetic resonance imaging was required for diagnosis among 74% of patients; computerized tomography findings were usually normal. Patients with EV had significantly higher mean CSF IFN-gamma (P = 0.005) and IL-10 (P = 0.05) than patients with ADEM and controls without CSF pleocytosis. CSF from ADEM patients had CSF cytokine values statistically similar to those of 3 patients subsequently diagnosed with MS.

CONCLUSIONS

ADEM is a potentially severe demyelinating disorder likely to be increasingly diagnosed as more magnetic resonance imaging studies are performed on patients with acute encephalopathy. Further characterization of the central nervous system inflammatory response will be needed to understand ADEM pathogenesis, to improve diagnostic and treatment strategies and to distinguish ADEM from MS.

Rates of antimicrobial resistance among common bacterial pathogens causing respiratory, blood, urine, and skin and soft tissue infections in pediatric patients

Antimicrobial resistance patterns among the principal bacterial pathogens from infections of the respiratory tract, blood, skin and soft tissue, and urinary tract of pediatric patients from the USA, Canada, Germany, France, and Italy were studied using the The Surveillance Network (TSN) database. Among Streptococcus pneumoniae isolates from respiratory tract infections, the prevalence of high-level penicillin resistance (MIC>/=2 microg/ml) ranged from 1.1 (Italy) to 36.2% (USA); erythromycin resistance was higher, ranging from 13.4 (Germany) to 63.8% (France). The prevalence of beta-lactamase-positive Haemophilus influenzae among isolates from lower respiratory tract infections ranged from <10 (Italy and Germany) to 38.4% (USA). Among isolates from blood and skin and soft tissue infections, the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) ranged from 7.2% (Canada and Germany) to 27.3% (Italy). The prevalence of Escherichia coli and Klebsiella pneumoniae with putative extended-spectrum beta-lactamases among isolates from blood, urinary tract, and skin and soft tissue infections ranged from 0 (Germany and France) to 29.6% (Italy). With the exception of pseudomonal infections or infections with MRSA, amoxicillin-clavulanate retained moderate activity, whilst ceftriaxone and cefepime were the most effective broad-spectrum injectable agents. Meropenem was the most effective agent against Pseudomonas aeruginosa with <5% resistance. Low levels of resistance, along with acceptable safety profiles and the availability of convenient oral formulations, continue to support the use of ceftriaxone, cefepime, amoxicillin-clavulanate, and meropenem as viable options for the treatment of infections in pediatric patients.

Pneumococcal Endocarditis in Children

Endocarditis due to Streptococcus pneumoniae is unusual in children, accounting for 3%-7% of all cases of childhood endocarditis. The US Pediatric Multicenter Pneumococcal Surveillance Group has prospectively identified patients with invasive disease at 8 children's hospitals. During the period of 1 September 1993 through 28 February 2003, a total of 11 children with pneumococcal endocarditis were seen. Seven (64%) were 3-36 months old; 8 (73%) were boys. Ten (91%) had preexisting structural heart disease; 5 had undergone previous heart surgery. Concomitant sites of infection were noted in 6 patients (55%), including 3 patients with meningitis. One patient (9%) died during hospitalization, and 5 others (45%) experienced serious complications. Only 2 patients remained hospitalized for their entire course of parenteral antibiotic therapy. Eight of 10 pneumococcal isolates tested were vaccine or vaccine-related serotypes included in the currently licensed 7-valent conjugated pneumococcal vaccine. Pneumococcal endocarditis in children is unusual but often has serious complications.

Prevalence of antimicrobial resistance in bacteria isolated from central nervous system specimens as reported by U.S. hospital laboratories from 2000 to 2002

Background

Bacterial infections of the central nervous system, especially acute infections such as bacterial meningitis require immediate, invariably empiric antibiotic therapy. The widespread emergence of resistance among bacterial species is a cause for concern. Current antibacterial susceptibility data among central nervous system (CNS) pathogens is important to define current prevalence of resistance.

Methods

Antimicrobial susceptibility of pathogens isolated from CNS specimens was analyzed using The Surveillance Database (TSN^®) USA Database which gathers routine antibiotic susceptibility data from >300 US hospital laboratories. A total of 6029 organisms derived from CNS specimen sources during 2000–2002, were isolated and susceptibility tested.

Results

Staphylococcus aureus (23.7%) and Streptococcus pneumoniae (11.0%) were the most common gram-positive pathogens. Gram-negative species comprised approximately 25% of isolates. The modal patient age was 1 or <1 year for most organisms. Prevalence of MRSA among S. aureus from cerebrospinal fluid (CSF) and brain abscesses were 29.9–32.9%. Penicillin resistance rates were 16.6% for S. pneumoniae, 5.3% for viridans group streptococci, and 0% for S. agalactiae. For CSF isolates, ceftriaxone resistance was S. pneumoniae (3.5%), E. coli (0.6%), Klebsiella pneumoniae (2.8%), Serratia marcescens (5.6%), Enterobacter cloacae (25.0%), Haemophilus influenzae (0%). Listeria monocytogenes and N. meningitidis are not routinely susceptibility tested.

Conclusions

Resistance is commonly detected, albeit still at relatively low levels for key drugs classes such as third-generation cephalosporins. This data demonstrates the need to consider predominant resistance phenotypes when choosing empiric therapies to treat CNS infections.

Decrease of invasive pneumococcal infections in children among 8 children's hospitals in the United States after the introduction of the 7-valent pneumococcal conjugate vaccine

OBJECTIVE

To monitor clinical and microbiologic features including antimicrobial susceptibility and serogroup distribution of invasive infections caused by Streptococcus pneumoniae among children before and after the introduction of routine administration of the 7-valent pneumococcal conjugate vaccine (PCV7).

DESIGN

A 9-year (January 1, 1994 through December 31, 2002) prospective surveillance study of all invasive pneumococcal infections in children.

PATIENTS

Infants and children cared for at 8 children's hospitals in the United States with culture-proven invasive infections caused by S pneumoniae.

RESULTS

When compared with the mean of the years 1994 to 2000, the annual number of invasive pneumococcal infections for children < or =24 months of age declined 58% in 2001 and 66% in 2002. If only the serogroups in the PCV7 are considered, the number of cases in children < or =24 months old declined 63% and 77% in 2001 and 2002, respectively. The greatest decrease was observed for serogroup-14 isolates. The number of isolates in nonvaccine serogroups increased 28% in 2001 and 66% in 2002 for children < or =24 months old. Nonvaccine serogroup-15 and -33 isolates had the greatest increase in number. The proportion of all isolates nonsusceptible to penicillin increased yearly from 1994 to 2000, reached a plateau in 2001 at 45%, and declined to 33% in 2002. Decrease in nonsusceptibility to penicillin occurred entirely in the isolates with penicillin minimum inhibitory concentration > or =2 microg/mL. Nonsusceptibility to penicillin increased slightly among nonvaccine-serotype isolates. Most infections after at least 2 doses of PCV7 were caused by nonvaccine-serotype isolates.

CONCLUSIONS

Since the introduction of the PCV7, the number of invasive pneumococcal infections caused by vaccine-serogroup isolates among 8 US children's hospitals has decreased >75% among children < or =24 months old. In addition, penicillin resistance decreased in 2002 for the first time since our surveillance began in 1993-1994. However, we have noted that replacement may be developing with serogroups 15 and 33. Furthermore, penicillin resistance seems to be increasing among nonvaccine serogroups. Surveillance must be continued to detect the emergence of changes in the distribution of serotypes as well as antibiotic susceptibility.

Clinical challenges of nosocomial infections caused by antibiotic-resistant pathogens in pediatrics

Antibiotic resistance in nosocomial infections is an ever-increasing problem as health care institutions provide care for children with more complicated medical and surgical problems. Several mechanisms of antibiotic resistance are reviewed for both gram-negative and gram-positive nosocomial pathogens. These adaptive resistance mechanisms allow organisms to survive in an environment of extensive antibiotic use and result in clinically significant infections. Mobile genetic elements have facilitated the rapid spread of antibiotic resistance within and among species. The clinical challenge faced by many practitioners is to understand these mechanisms of antibiotic resistance and to develop strategies for successfully treating infection caused by resistant pathogens. Nosocomial outbreaks caused by resistant organisms are described, and an approach to empiric therapy based on presumed pathogens, site of infection, and local resistance patterns is discussed.

Streptococcus pneumoniae infections in the neonate

OBJECTIVE

Streptococcus pneumoniae infections in the neonate (SPIN) are relatively unusual events (1%-11% of neonatal sepsis) but are associated with substantial morbidity and mortality. Previous reports suggest that invasive SPIN is associated with prolonged rupture of membranes, maternal colonization/illness, prematurity, early-onset pneumonia presentation (<72 hours), and high mortality (50%). The aim of this study was to review the current epidemiology and clinical course of SPIN.

METHODS

The US Pediatric Multicenter Pneumococcal Surveillance Group has been prospectively monitoring S pneumoniae infections since 1993 in 8 children's hospitals. For this report, data were gathered retrospectively from the charts of neonates who were 30 days of age and younger and had SPIN from September 1993 to February 2001. All pneumococcal isolates were sent to a central laboratory for serogrouping/typing and susceptibility testing.

RESULTS

Twenty-nine cases of SPIN were identified from a total of 4428 episodes of S pneumoniae infection in children. Sixty-six percent were male, and 55% were white; the mean age was 18.1 day (+/-8.2). Ninety percent of infants were >or=38 weeks' gestation. Two mothers had bacterial infections at delivery; 1 had S pneumoniae isolated from both blood and cervix, and 1 had clinical amnionitis. The primary diagnoses in the neonates were bacteremia (8), meningitis (8), bacteremic pneumonia (4), septic arthritis/osteomyelitis (1), and otitis media (8). Thirty percent of infants with invasive SPIN presented with leukopenia/neutropenia, but this did not predict poor outcome. The infecting pneumococcal serogroups were 19 (32%); 9 (18%); 3 and 18 (11% each); 1, 6, and 14 (7% each); and 5 and 12 (3.5% each). Twenty-six percent of invasive neonatal infections were caused by serogroups 1, 3, 5, and 12, which are not contained in the heptavalent pneumococcal vaccine. In contrast, 6% of invasive nonneonatal disease was caused by these same nonvaccine serogroups. Susceptibility testing demonstrated that 21.4% of isolates were penicillin nonsusceptible and 3.6% were ceftriaxone nonsusceptible. Three (14.3%) neonates with invasive SPIN died; all deaths occurred within 36 hours of presentation. Deaths did not appear to be related to pneumococcal serogroup or susceptibilities.

CONCLUSIONS

Compared with previous studies of neonates with pneumococcal infection, this series showed that infants with SPIN were usually 2 to 3 weeks of age at presentation; likely to be full term; and ill with pneumonia, meningitis, and otitis media. This late-onset presentation was associated with an overall mortality rate of 10.3% (14.3% for invasive disease).

Macrolide resistance among middle ear isolates of Streptococcus pneumoniae observed at eight United States pediatric centers: prevalence of M and MLSB phenotypes

BACKGROUND

Increasing macrolide resistance among middle ear isolates complicates treatment of otitis media in children. When macrolide resistance is mediated via an efflux pump (M phenotype), the MICs of erythromycin, clarithromycin and azithromycin are usually below 32 microg/ml, and the pneumococcus remains susceptible to clindamycin. The association of prior specific macrolide therapy with the isolation of a macrolide resistant strain has not been reported.

OBJECTIVES

To determine the mechanism of macrolide resistance in Streptococcus pneumoniae recovered from the middle ears of children with otitis media and their association, if any, with ethnicity, age, serogroup/serotype and prior antibiotic therapy.

METHODS

Middle ear isolates collected by members of the United States Pediatric Multicenter Pneumococcal Surveillance Group during a 6-year period from September 1994 through August 2000 were studied. Antibiotic susceptibility to penicillin and ceftriaxone was determined by microbroth dilution. Disc diffusion susceptibility to erythromycin and clindamycin was performed to categorize macrolide resistance mechanisms. The medical record was reviewed to determine demographics and history of previous antibiotic therapy. Isolates were serogrouped or serotyped by the capsular swelling method.

RESULTS

Of the 1088 isolates available for testing, 51% were nonsusceptible to penicillin and 37% were nonsusceptible to erythromycin. Erythromycin resistance increased form 15% in 1994 through 1995 to 56% in 1999 through 2000. Seventy-five percent of macrolide-resistant strains were M phenotype. Macrolide resistance was less likely in isolates recovered from African-Americans and more likely in isolates obtained from children <3 years of age and from isolates obtained at time of tympanostomy tube placement. Neither erythromycin, nor clarithromycin nor azithromycin prescribed in the 30 days before infection was more likely than another to be associated with increased macrolide resistance. However, any macrolide alone or in combination with another antimicrobial taken before infection was associated with increased macrolide resistance among the S. pneumoniae organisms isolated from the middle ear.

CONCLUSIONS

Macrolide resistance among middle ear isolates of S. pneumoniae increased during the 6-year study. The proportion of M phenotype remained constant at 75%, meaning that these isolates remain susceptible to clindamycin. Continued surveillance to document potential changes is essential.

On the importance of early reflections for speech in rooms

This paper presents the results of new studies based on speech intelligibility tests in simulated sound fields and analyses of impulse response measurements in rooms used for speech communication. The speech intelligibility test results confirm the importance of early reflections for achieving good conditions for speech in rooms. The addition of early reflections increased the effective signal-to-noise ratio and related speech intelligibility scores for both impaired and nonimpaired listeners. The new results also show that for common conditions where the direct sound is reduced, it is only possible to understand speech because of the presence of early reflections. Analyses of measured impulse responses in rooms intended for speech show that early reflections can increase the effective signal-to-noise ratio by up to 9 dB. A room acoustics computer model is used to demonstrate that the relative importance of early reflections can be influenced by the room acoustics design.

Endotoxin content in renal calculi

PURPOSE

Manipulation of infection calculi (struvite and calcium apatite) can cause the sepsis syndrome due to endotoxemia or bacteremia. We sought to determine whether concentrations of endotoxin sufficient to produce the sepsis syndrome could be embedded in renal infection stones.

MATERIALS AND METHODS

Fragments of infection and noninfection renal calculi were processed and assayed for endotoxin concentration. Endotoxin concentrations, recorded as endotoxin units per gm. calculus, were converted to ng. (10 endotoxin units = 1 ng.). Urine culture results were available for some patients with infection stones.

RESULTS

A total of 34 renal calculi (16 infection and 18 noninfection) were evaluated. The composition of 62.5% of the infection stones was struvite, whereas 50% of the noninfection stones were calcium oxalate monohydrate. Mean endotoxin concentration in infection calculi was 12,223 ng./gm. stone (range 0.6 to 50,000), compared to 340.3 ng./gm. stone (range 0 to 3,490) in noninfection calculi. The endotoxin content difference was significant (p = 0.001). Urine culture results available from 9 patients with infection stones did not correlate with endotoxin concentrations.

CONCLUSIONS

Large endotoxin concentrations can be found in renal infection calculi. Noninfection stones can contain endotoxin but in much lower amounts. Massive endotoxin release could occur with infection stone manipulation, possibly producing increased serum endotoxin concentrations similar to those seen in gram-negative sepsis. Anti-endotoxin strategies may be beneficial in preventing and treating stone induced endotoxemia and the sepsis syndrome.

Preparation of a mesoporous silicon boron nitride via a non-aqueous sol-gel route

A silicon boron imide based gel Si3B(NH)x(NH2)y(NMe2)z was prepared via catalytic ammonolysis of tris[tris(dimethylamino)silylamino]boron B[HNSi[N(CH3)2]3]3; pyrolysis of the gel under ammonia at 1,000 degrees C gives a mesoporous silicon boron nitride with high surface area and narrow pore size distribution.

In vitro activities of cethromycin (ABT-773), a new ketolide, against Streptococcus pneumoniae strains that are not susceptible to penicillin or macrolides

Pneumococcal resistance to antimicrobials presents problems to physicians for empirical treatment of acute otitis media (AOM). Three hundred thirty-three isolates of Streptococcus pneumoniae selected for nonsusceptibility to penicillin (MIC >0.1 microg/ml) from the middle ear (n = 325) or mastoid (n = 8) of children seen between 1994 and 2000 at four children's hospitals in the United States were tested by broth microdilution for susceptibility to nine antibiotics. Using NCCLS 2002 breakpoints, resistance to the following drugs was as indicated: amoxicillin, 1%; azithromycin, 71%; cefprozil, 71%; ceftriaxone, 2%; cefdinir, 98%; erythromycin, 70%; levofloxacin, 0%; and trimethoprim-sulfamethoxazole, 93%. Of the penicillin- and erythromycin-nonsusceptible isolates, 97% were inhibited by cethromycin (ABT-773) and 83% were inhibited by telithromycin at a concentration of <or=0.125 microg/ml. Macrolide resistance among penicillin-nonsusceptible pneumococci increased from 44 to 80% in the 6 years of the study from which the isolates were selected; however, the proportion of isolates with M or MLS(B) phenotypes remained constant over the time period (53 and 18%, respectively). Prior treatment with a macrolide or clindamycin alone or in combination with a beta-lactam resulted in 94 or 85% of isolates causing infections being macrolide and or clindamycin resistant. No prior individual macrolide (azithromycin, erythromycin, or clarithromycin) resulted in more macrolide resistance or in a more prevalent resistance phenotype. The ketolides appear to be active antimicrobials against penicillin- and macrolide-resistant pneumococci.

Clinical characteristics of children with complicated pneumonia caused by Streptococcus pneumoniae

OBJECTIVE

The frequency of children who are hospitalized with pneumococcal pneumonia complicated by necrosis, empyema/complicated parapneumonic effusion, and lung abscess seems to be increasing. The factors that contribute to this increase are unclear; therefore, the objective of this study was to describe and compare the relative frequency, clinical characteristics, and outcome of hospitalized children with complicated pneumonia with those of children with uncomplicated pneumonia caused by Streptococcus pneumoniae in the era of antibiotic resistance.

METHODS

A multicenter, retrospective study of 8 children's hospitals in the United States was undertaken. A total of 368 children who were hospitalized with pneumococcal pneumonia identified from patients enrolled in the US Pediatric Multicenter Pneumococcal Surveillance Study over the period from September 1, 1993, to January 31, 2000 were studied. Demographic and clinical variables, antibiotic susceptibility, pneumococcal serotypes, antimicrobial therapy, and clinical outcome in hospitalized children with complicated versus uncomplicated pneumococcal pneumonia were measured.

RESULTS

A total of 368 patients with pneumococcal pneumonia were identified. Of the 368 isolates, 47 (12.8%) were intermediate and 37 (10.1%) were resistant to penicillin; 18 (5%) were intermediate to ceftriaxone, and 9 (2.5%) were resistant to ceftriaxone. A total of 133 patients met the criteria for complicated pneumonia and had a chest tube placed; 56 of these patients subsequently underwent decortication. The proportion of hospitalized patients with complicated pneumococcal pneumonia increased progressively over the study period from 22.6% in 1994 to 53% in 1999. Patients with complicated disease were older (median age: 45 vs 27 months) and significantly more likely to be of white race and have chest pain on presentation compared with patients with uncomplicated disease. Patients who had complicated disease and underwent decortication were more likely to have pleural fluid lactate dehydrogenase levels of >7500 IU/L compared with those patients who had chest tube placement alone. Fifty-three percent of children who were > or =61 months of age and were hospitalized had complicated pneumonia. This group of children accounted overall for 42% of the patients with complicated pneumonia, 48.2% of the patients who subsequently underwent decortication, and 44% of the patients who had received a course of antibiotics before diagnosis. Pneumococcal serotypes 1, 6, 14, and 19 were the most prevalent serotypes causing disease, with serotype 1 causing 24.4% of the complicated cases versus 3.6% of the uncomplicated cases. Ninety-eight percent of the patients in both groups recovered from their pneumonia. Antibiotic resistance was not found to be more prevalent in those patients with complicated disease.

CONCLUSIONS

The relative frequency of complicated disease in hospitalized children with pneumococcal pneumonia is increasing. Patients with complicated pneumococcal disease were older and significantly more likely to be of white race compared with those patients with uncomplicated disease. Pneumococcal serotype 1 caused significantly more disease in patients with complicated versus uncomplicated pneumonia. Patients with complicated disease were not more likely to be infected with an antibiotic-resistant isolate.

Management of community-acquired pediatric pneumonia in an era of increasing antibiotic resistance and conjugate vaccines

The antibiotic management of infants and children with pneumonia is based on the clinician's assessment of the most likely infecting pathogens, the susceptibilities of the infecting pathogens and the seriousness of the illness. The bacterial etiology of pneumonia changed significantly following the universal use of protein-conjugated vaccines for Haemophilus influenzae type b. Similar significant changes are likely to occur with universal use of protein-conjugated vaccines for Streptococcus pneumoniae, requiring the clinician to alter assumptions of the risk of invasive bacterial infection in the child who presents with pneumonia. New strategies are likely to require fewer ancillary tests (e.g. white blood cell count, C-reactive protein and blood culture) and suggest a decreased need for empiric antibiotic therapy. Although the majority of lower respiratory tract infections in children have a viral etiology and are not amenable to antibiotic therapy, for the seriously ill child who is thought to be likely to have pneumonia caused by a bacterial pathogen, recent changes in the susceptibility patterns of both common organisms such as S. pneumoniae and more unusual pulmonary pathogens such as Staphylococcus aureus have forced changes in the selection of both empiric and definitive antibiotic therapy. Third generation cephalosporins ceftriaxone and cefotaxime appear to be effective therapy for pneumonia caused by virtually all current isolates of S. pneumoniae. In contrast antibiotic regimens for life-threatening pulmonary infections in which Staphylococcus aureus is a suspected pathogen should include vancomycin.

Staghorn calculus endotoxin expression in sepsis

Staghorn calculi are infrequent and generally are infected stones. Struvite or apatite calculi are embedded with gram-negative bacteria, which can produce endotoxin. Sepsis syndrome may occur after surgical therapy or endoscopic manipulation of infected or staghorn calculi. Sepsis, which can occur despite perioperative antibiotic use, may be due to bacteremia or endotoxemia. We present a child with an infected staghorn calculus who developed overwhelming sepsis and died after percutaneous stone manipulation. Endotoxin assay of stone fragments demonstrated an extremely high level of endotoxin despite low colony bacterial culture growth. This is the first reported case in which endotoxin was demonstrated in stone fragments from a child who died of severe sepsis syndrome after percutaneous staghorn stone manipulation.

Invasive pneumococcal infections in children with asplenia

BACKGROUND

Asplenia is associated with an increased risk of infections caused by Streptococcus pneumoniae. Overwhelming infection can be fulminate and lead to a fatal outcome.

OBJECTIVE

To review the epidemiology and clinical course of invasive S. pneumoniae infections in children with asplenia before the release of the conjugate pneumococcal vaccine.

METHODS

Children with S. pneumoniae infections from eight children's hospitals in the US were identified prospectively from September, 1993, to August, 1999. Further demographic, medical and microbiologic information was gathered retrospectively from the charts of patients with asplenia.

RESULTS

Twenty-two asplenic patients with 26 episodes of invasive S. pneumoniae were identified. This represents 1% of the 2,581 episodes of invasive S. pneumoniae infections identified in our study. Twelve had congenital asplenia (CA), and 10 had undergone surgical splenectomy. Nine of the patients with CA had associated complex congenital heart disease. The median age at first infection was 12.5 months for CA patients as compared with 69 months in children with surgical splenectomy (P < 0.001). Seventy-five percent of those eligible had received the polysaccharide pneumococcal vaccine. The most common serotypes isolated were 6B (8), 23F (7), 18C (2) and 19A (2). Antimicrobial prophylaxis had been prescribed for 82% of the study cohort. Clinical presentations of the 26 episodes included fever (22), shock (7), petechiae or purpura (7), disseminated intravascular coagulation (5) and respiratory distress (5). Clinical illness included bacteremia alone (12), meningitis alone (8), bacteremia with otitis media-sinusitis (3), bacteremia with pneumonia (2) and meningitis with osteomyelitis (1). Five of the 6 patients who died had meningitis. Three of the survivors (19%) had significant morbidity, and all of them had meningitis. Two patients had 2 episodes each, and 1 patient had 3 episodes. All but 1 of the multiple episodes was with a different serotype. Forty-six percent of isolates were nonsusceptible to penicillin, and 19% were nonsusceptible to ceftriaxone. There was no association between antimicrobial resistance and mortality.

CONCLUSIONS

Invasive pneumococcal disease in patients with asplenia has a high mortality, especially in those with meningitis. Even though the new conjugate vaccine might increase protection, 19% of patients had disease caused by serotypes not included in the current heptavalent vaccine. Clinicians should continue to be aggressive in evaluating asplenic patients with unexplained fevers.

Old and new antibiotics for pediatric pneumonia

A variety of antibiotics, both parenteral and oral, are available to the clinician caring for a child with pneumonia. Although viral pathogens are the common etiologic agents causing community-acquired pneumonia, significant morbidity and mortality exists from disease caused by bacteria and atypical pneumonia agents. Treatment of nosocomial bacterial pneumonia has become particularly difficult with ever-increasing resistance documented in hospital-acquired organisms. This article discusses antibiotic therapy based on clinical presentation and based on identified pathogens, with a discussion of mechanisms of antibiotic resistance and the newer agents that have been designed to meet this continually evolving challenge.

Pediatric acute hemorrhagic leukoencephalitis: report of a surviving patient and review

Acute hemorrhagic leukoencephalitis (AHLE) is a rare, fulminant CNS demyelinating condition usually diagnosed at autopsy. We report the clinical, laboratory, radiographic, and pathologic features of the first nonfatal case of pediatric AHLE confirmed by brain biopsy. Pathologic diagnosis of this condition may be critical to exclude more-common processes and to expedite the decision to administer high-dose corticosteroid therapy, which is potentially lifesaving.

Six year multicenter surveillance of invasive pneumococcal infections in children

OBJECTIVE

Monitor clinical and microbiologic features including antimicrobial susceptibility of invasive pneumococcal infections among children.

DESIGN

A 6-year (September, 1993, through August, 1999) prospective surveillance study of all invasive pneumococcal infections in children.

PATIENTS

Infants and children cared for at eight children's hospitals in the United States with culture-proved invasive pneumococcal infection.

RESULTS

During the 6-year period 2581 episodes of invasive pneumococcal infection occurred in 2498 children. Underlying conditions were present in 29% of the children. Of children without an underlying condition, 15% of the total infections occurred in those 25 to 60 months old. As the ages of the children advanced the proportion of cases classified as bacteremia declined, whereas the proportion classified as pneumonia increased. Also, as the ages of the children increased the proportion of isolates in serotypes/serogroups 1, 3 and 23 increased. whereas the proportion for serotype 14 diminished. During the 6 years of the study, there was a significant increase in the percentage of isolates intermediate or resistant to penicillin (P < 0.000001) or intermediate to ceftriaxone (P < 0.002). By the sixth year of the study, 37 and 11% of the isolates were nonsusceptible to penicillin or ceftriaxone, respectively. Antibiotic use in the 30 days before diagnosis of systemic pneumococcal infection occurred in 30 to 35% of the children for each of the 6 years. The overall case-fatality rate for children with systemic pneumococcal infection was 1.56%. Mortality was greatest in children >60 months old and in those with underlying conditions; mortality was not related to antibiotic susceptibility.

CONCLUSIONS

The percentage of pneumococcal isolates recovered from children with systemic infection which were intermediate for penicillin or ceftriaxone or resistant to penicillin increased steadily during the 6-year period. There was also a trend toward increasing rates of resistance to ceftriaxone. The age and serogroup/serotype distributions of our patients support the recommendations to consider administration of the seven valent pneumococcal conjugate vaccine for all children 24 to 59 months old, with special consideration for selected groups.