Clinical outcome of invasive infections by penicillin-resistant Streptococcus pneumoniae in Korean children

Cost-effectiveness of a national immunization program with the 13-valent pneumococcal conjugate vaccine compared with the 10-valent pneumococcal conjugate vaccine in South Korea

Introduction

Globally, pneumococcal disease represents a significant burden. South Korea implemented the 7-valent pneumococcal conjugate vaccine (PCV7) in 2003, replaced with the 10-valent (PCV10) and 13-valent (PCV13) vaccine in 2010. In 2014, both vaccines were introduced in the national immunization program (NIP) for infants with 3 primary doses and one booster dose We performed a cost-effectiveness evaluation to elucidate which vaccine may be expected to provide greater impact if included in a NIP.

Methodology

Using an established model, we estimated the impact of introducing either PCV13 or PCV10 into the South Korean NIP in 2015. Vaccine impact was based on historic observed impact of PCV13 from 2010 to 2015 in Korea given high uptake of PCV13, and PCV10 impact was estimated based on experiences in countries using PCV10. Incidence and costs for all ages and including invasive pneumococcal disease, pneumonia, and acute otitis media were derived from the literature and Health Insurance Review and Assessment database.

Results

In the base-case, over 5-years PCV13 was estimated to avert 550,000 more cases of pneumococcal disease compared to PCV10, driven by broader serotype coverage and less replacement due to serotypes 3 and 19A. This translated to a cost-savings of $47.4 million USD despite PCV13’s higher cost. Sensitivity analysis found incremental cost-effectiveness ratios (ICERs) ranged from cost-saving to $7,300 USD per quality-adjusted life year (QALY).

Conclusion

A NIP using PCV13 was estimated to have a more substantial public health impact and be cost-saving compared to a program with PCV10 due to broader serotype coverage.

The changing epidemiology of childhood pneumococcal disease in Korea

The wide use of antimicrobial agents and 7-valent pneumococcal conjugate vaccine (PCV7) has led to major changes in the epidemiology of childhood pneumococcal diseases. In Korea, data on the population-based incidence of childhood invasive pneumococcal diseases (IPD) are not available; however, institution-based surveillance data suggest a substantial burden of childhood IPD. Following the introduction of the PCV7 in Korea in 2003, the proportion of IPD caused by vaccine-type pneumococci has decreased, while non-PCV7 serotypes, especially serotypes 19A and 6A, whose proportions had been increasing before the introduction of the vaccine, became predominant among childhood IPD isolates. This article reviews the overall impact of PCV7 utilization and summarizes the results obtained so far. Continuous monitoring and gathering of scientific evidence for the epidemiological transition of pneumococcal carriage and IPD will be important for the management of pneumococcal infections in Korea.

Pharmacotherapy for pneumococcal infections: an update

INTRODUCTION

The management of pneumococcal diseases still places a significant burden on medical and economic resources. The subjects at greatest risk of pneumococcal infections are children.

AREAS COVERED

The aim of this review is to analyse the best current therapeutic approach to pneumococcal resistance, taking into account the level of susceptibility of Streptococcus pneumoniae, and the pharmacokinetics and pharmacodynamics of different antibiotics in the various pneumococcal diseases.

EXPERT OPINION

Antibiotic treatment of a number of pneumococcal diseases remains difficult or impossible due to the presence of strains resistant to commonly used antibiotics. In children the problem is significantly more important than in adults due to the reduced number of licenced drugs for subjects in the first years of life. The new conjugate pneumococcal vaccines containing 10 (PCV10) and 13 serotypes (PCV13), which include most of the recently emerging strains, might reduce the incidence of pneumococcal infections and the circulation of resistant pathogens. However, it is likely that optimal results will only be reached after the development of effective vaccines based on conserved proteins that are capable of preventing all pneumococcal infections, regardless of the serotype of the causative organism.

Impact of penicillin nonsusceptibility on clinical outcomes of patients with nonmeningeal Streptococcus pneumoniae bacteremia in the era of the 2008 clinical and laboratory standards institute penicillin breakpoints

To investigate the impact of penicillin nonsusceptibility on clinical outcomes of patients with nonmeningeal Streptococcus pneumoniae bacteremia (SPB), a retrospective cohort study was performed. The characteristics of 39 patients with penicillin-nonsusceptible SPB (PNSPB) were compared to those of a group of age- and sex-matched patients (n = 78) with penicillin-susceptible SPB (PSSPB). Susceptibility to penicillin was redetermined by using the revised Clinical and Laboratory Standards Institute (CLSI) penicillin breakpoints in CLSI document M100-S18. Although the PNSPB group tended to have more serious initial manifestations than the PSSPB group, the two groups did not differ significantly in terms of their 30-day mortality rates (30.8% versus 23.1%; P = 0.37) or the duration of hospital stay (median number of days, 14 versus 12; P = 0.89). Broad-spectrum antimicrobial agents, such as extended-spectrum cephalosporins, vancomycin, and carbapenem, were frequently used in both the PNSPB and PSSPB groups. Multivariate analysis revealed that ceftriaxone nonsusceptibility (adjusted odds ratio [aOR] = 4.88; 95% confidence interval [CI] = 1.07 to 22.27; P = 0.041) was one of the independent risk factors for 30-day mortality. Thus, when the 2008 CLSI penicillin breakpoints are applied and the current clinical practice of using wide-spectrum empirical antimicrobial agents is pursued, fatal outcomes in patients with nonmeningeal SPB that can be attributed to penicillin nonsusceptibility are likely to be rare. Further studies that examine the clinical impact of ceftriaxone nonsusceptibility in nonmningeal SPB may be warranted.

Risk factors for 30-day mortality in adult patients with pneumococcal bacteraemia, and the impact of antimicrobial resistance on clinical outcomes

The clinical impact of antimicrobial resistance on the outcome of pneumococcal bacteraemia has remained unclear. This study aimed to evaluate risk factors for mortality and determine the impact of antimicrobial resistance on clinical outcomes. A total of 150 adult patients with pneumococcal bacteraemia were identified over a period of 11 years at Seoul National University Hospital. Of the 150 patients, 122 (81·3%) had penicillin-susceptible (Pen-S) strains and 28 (18·7%) penicillin-non-susceptible (Pen-NS) strains; 43 (28·7%) had erythromycin-susceptible (EM-S) strains and 107 (71·3%) erythromycin-non-susceptible (EM-NS) strains. On multivariate analysis, elevated APACHE II score [odds ratio (OR) 1·24, 95% confidence interval (CI) 1·14–1·34, P<0·001) and presence of solid organ tumour (OR 2·99, 95% CI 1·15–7·80, P=0·025) were independent risk factors for mortality. Neither erythromycin resistance nor penicillin resistance had a significant effect on clinical outcomes. However, for the 76 patients with pneumococcal pneumonia, the time required for defervescence was significantly longer in the EM-NS group than in the EM-S group (5·45±4·39 vs. 2·93±2·56, P=0·03 by log rank test). In conclusion, antimicrobial resistance does not have an effect on mortality in adult patients with pneumococcal bacteraemia.

Clinical and economic burden of community-acquired pneumonia amongst adults in the Asia-Pacific region

Community-acquired pneumonia (CAP) is an important cause of mortality and morbidity amongst adults in the Asia-Pacific region. Literature published between 1990 and May 2010 on the clinical and economic burden of CAP amongst adults in this region was reviewed. CAP is a significant health burden with significant economic impact in this region. Chronic obstructive pulmonary disease, cardiovascular disease, diabetes mellitus and advanced age were risk factors for CAP. Aetiological agents included Streptococcus pneumoniae, Klebsiella pneumoniae, Gram-negative bacteria, Mycobacterium tuberculosis, Burkholderia pseudomallei, Staphylococcus aureus and atypical pathogens (Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella spp.), with important differences in the prevalence of these pathogens within the region. Antibiotic resistance was significant but was not linked to excess mortality. Aetiological pathogens remained susceptible to newer antimicrobial agents. Rational antibiotic use is essential for preventing resistance, and increased surveillance is required to identify future trends in incidence and aetiology and to drive treatment and prevention strategies.

Global prevailing and emerging pediatric pneumococcal serotypes

Streptococcus pneumoniae is the leading cause of vaccine-preventable deaths among children younger than 5 years of age worldwide. The 7-valent pneumococcal conjugate vaccine (PCV7) is currently licensed in more than 90 countries and has contributed to significant declines in the incidence of invasive pneumococcal disease (IPD). Recent studies report an increased incidence of IPD caused by non-PCV7 vaccine serotypes (NVTs). Seroepidemiology of IPD caused by NVTs following the introduction of PCV7 is of interest, and this article provides a comprehensive global summary of the prevailing and emerging serotypes causing IPD in children. Currently, globally emerging or persistent NVTs include serotypes 1, 3, 5, 6A, 7F and 19A. Serotypes included in the recently licensed 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13) account for pneumococcal disease burdens in most developed countries of 65-85% and 80-90%, respectively. The seroprevalence of NVTs after widespread use of PCV10 and PCV13 requires ongoing monitoring.

Antibiotic resistance in invasive Streptococcus pneumoniae isolates identified in Scotland between 1999 and 2007

Data from 4727 invasive isolates of Streptococcus pneumoniae submitted to the Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory between 1999 and 2007 were analysed to establish susceptibility profiles to penicillin, erythromycin and cefotaxime. Pneumococcal resistance to penicillin over the study period remained low, with only 0.2 % (n=7/4727) of isolates falling into this category (MIC ≥2 mg l(-1)). These isolates have been sporadic, and have mainly represented serogroup 14 (ST9) and 9 (ST156). In comparison, the 'intermediate sensitivity' group (MIC 0.12-1 mg l(-1)) ranged between 2 and 6 % per year, the majority from serogroup 9 (ST156). Over the study period, we found that 12 % (n=585/4727) of isolates were erythromycin-resistant (MIC >0.5 mg l(-1)), with the majority (n=467; 80 %) of these isolates identified as serogroup 14 (ST9). Cephalosporin resistance (cefotaxime MIC >1 mg l(-1)) was found in only 0.06 % (n=2/3135) of isolates. Internationally recognized clones (Pneumococcal Molecular Epidemiology Network) accounted for 35 % (n=28/81) of the penicillin non-susceptible isolates and 75 % (n=248/330) of the macrolide-resistant isolates, with ST9 and ST306 predominating. Between 1999 and 2007 we found that 11.6 % (n=18/155) of the penicillin non-susceptible isolates and 4.8 % (n=28/585) of the macrolide-resistant isolates were from serogroups not covered by the 7-valent conjugate pneumococcal vaccine in use in the UK since 2006. Susceptibility to first-line antimicrobial agents for invasive pneumococcal disease in Scotland remained high over the period 1999-2007.

Pneumococcal meningitis in Taiwanese children: emphasis on clinical outcomes and prognostic factors

Pneumococcal meningitis causes high morbidity or mortality in childhood despite the progress in medicine. Children with pneumococcal meningitis were identified and retrospectively reviewed. Forty-nine children were eligible, with mortality in 24.5% of all and neurological sequelae in 40.5% of survivors. In the analysis of clinical profiles, ventilator support (p = 0.001), septic shock (p < 0.001), multiple organ failure (p < 0.001) and lower cerebrospinal fluid (CSF) leukocyte count (p = 0.001) were more frequently found in non-survivors. Besides, CSF protein (p = 0.006) was higher in survivors with neurological sequelae. Initial dexamethasone usage and disease severity did not affect the occurrence of neurological sequelae. Multivariate logistic regression analysis revealed that CSF leukocyte count <or=200 mm(-3) (p = 0.013) and protein level >or=330 g l(-1) (p = 0.022) were significantly risk factors associated with poor outcomes, and physicians should be cautious if such conditions occur.

Pneumococcal antimicrobial resistance: therapeutic strategy and management in community-acquired pneumonia

Streptococcus pneumoniae has been consistently shown to represent the most frequent causative agent of community-acquired pneumonia (CAP) and pneumococcal antibiotic resistance towards different families of antibiotics continues to be a much-debated issue. Microbial resistance causes a great deal of confusion in choosing an empirical treatment for pneumonia and this makes it necessary to know which factors actually determine the real impact of antimicrobial resistance on the outcome of pneumococcal infections. Several different aspects have to be taken into account when analyzing this matter, such as the study design, the condition of the patient at the time of diagnosis, the choice of the initial antimicrobial regimen (combination or monotherapy) and the pharmacokinetic/pharmacodynamic variables of the chosen antibiotic. It is generally accepted that in the treatment of beta-lactam-resistant pneumococcal infections, the use of standard antipneumococcal beta-lactam agents is unlikely to impact negatively on the outcome of CAP when appropriate agents are given in sufficient doses. As a general rule, for infections with penicillin-sensitive strains, penicillin or an aminopenicillin in a standard dosage will be effective; in the cases of strains with intermediate resistance, beta-lactam agents are still considered appropriate treatment although higher dosages are recommended; finally, infections with isolates of high-level penicillin resistance should be treated with alternative agents such as the third-generation cephalosporins or the new antipneumococcal fluoroquinolones. In areas of high prevalence of high-level macrolide resistance, empirical monotherapy with a macrolide is not optimal for the treatment of hospitalised patients with moderate or moderately-severe CAP. Fluoroquinolones are considered to be excellent antibiotics in the treatment of pneumococcal CAP in adults, but their general recommendation has been withheld due to fears of a widespread development of resistance. Most international guidelines recommend combination therapy (beta-lactam plus a macrolide) for the treatment of hospitalised patients with CAP.

Epidemiology, clinical characteristics and antimicrobial resistance patterns of community-acquired pneumonia in 1702 hospitalized children in Singapore

OBJECTIVE AND BACKGROUND

Childhood community-acquired pneumonia (CAP) remains a leading cause of morbidity and mortality worldwide. The features of childhood CAP vary between countries. The aim of this study was to delineate the clinical characteristics, complications, spectrum of pathogens and patterns of antimicrobial resistance associated with hospitalized cases of childhood CAP in Singapore.

METHODS

A retrospective study was conducted of patients discharged from Singapore's only children's hospital over a 3-year period with a principal diagnosis of CAP.

RESULTS

A total of 1702 children, with a median age of 4.2 years (range: 1 month-16.3 years) were enrolled. A pathogen was identifiable in 38.4% of cases, including Mycoplasma pneumoniae in 20.3%, typical respiratory bacteria in 10.3% (64.6%Streptococcus pneumoniae; 21.7% non-typeable Haemophilus influenzae), viruses in 5.5% and mixed bacterial/viral infections in 2%. The majority of M. pneumoniae infections were in school-aged children (>5 years). Severity of infection was greater in CAP caused by typical bacteria, as reflected by length of hospital stay, CRP level, white cell and absolute neutrophil counts. Mortality from typical bacterial infections (8.9%) exceeded that from M. pneumoniae (0.3%) and viral pneumonias (0%) (P < 0.001). Aminopenicillins were often prescribed empirically for suspected S. pneumoniae and H. influenzae infections; however, resistance to these agents was frequently documented among S. pneumoniae (58.5%) and H. influenzae isolates (51%).

CONCLUSION

In Singaporean children hospitalized with CAP, M. pneumoniae is the most commonly identified causative organism, followed by common respiratory viruses, S. pneumoniae and H. influenzae. Streptococcus pneumoniae and H. influenzae are associated with greater severity of infection than other organisms, and have high levels of resistance to commonly prescribed antibiotics.

The roles of pneumococcal serotypes 1 and 5 in paediatric invasive disease

A small number of serotypes are responsible for most invasive pneumococcal disease in children worldwide. Serotypes 1 and 5 were among the first pneumococcal serotypes to be identified, reflecting their great prominence as causes of disease in the early part of the 20th century. In the antibiotic era, these serotypes persist as important causes of disease in children in most countries even though they, unlike some other common serotypes, remain sensitive to antimicrobial agents. These types also exhibit a high level of virulence, cause disease clusters or outbreaks, infect all age groups, and cause severe disease. Future vaccine formulations that protect against these types are important for developed and developing countries alike.

Therapeutic options for pneumococcal pneumonia in Turkey

BACKGROUND

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality worldwide. Streptococcus pneumoniae continues to be the most important causative agent in CAP.

OBJECTIVE

This article reviews options for the empiric treatment of pneumococcal pneumonia in Turkey based on local epidemiologic data.

METHODS

This was a retrospective review of studies evaluating antimicrobial susceptibility patterns among clinical isolates of S pneumoniae in Turkey from 2000 onward. Relevant studies were identified through literature searches of both Turkish (Ulakbim and Pleksus) and international (MEDLINE) databases using the search terms S pneumoniae and Turkey. Only antibiotics likely to be used in pneumococcal pneumonia were evaluated. The minimum concentration required to inhibit 90% of isolates (MIC(90)) for each antibiotic was obtained by averaging all reported values to arrive at a single value for the entire country.

RESULTS

The MIC(90) for penicillin was 1 g/mL; among all isolates of S pneumoniae, 6.4% were penicillin resistant and 30.9% showed intermediate susceptibility. The MIC(90)s and overall rates of resistance (combined intermediate susceptibility and resistance) for the other antibiotics studied were as follows: cefaclor, 4 microg/mL (26.3%); cefuroxime, 2 microg/mL (15.4%); ceftriaxone, 0.25 microg/mL (0.75%); imipenem, 0.06 microg/mL (0%); erythromycin, 2 microg/mL (13.9%); clarithromycin, 2 microg/mL (13.7%); azithromycin, 2 microg/mL (13.8%); telithromycin, 0.06 microg/mL (no published breakpoints); trimethoprim-sulfamethoxazole, 4 microg/mL (63.8%); tetracycline, 16 microg/mL (24.6%); ciprofloxacin, 2 microg/mL (no published breakpoints); ofloxacin, 2 microg/mL (4%); levofloxacin, 1 microg/mL (0%); gemifloxacin, 0.06 microg/mL (no published breakpoints); and moxifloxacin, 0.06 microg/mL (0%). Penicillin G, at standard parenteral doses, has been shown to achieve concentrations above the MIC for >40% to 100% of the dosing interval, depending on the MIC of the isolate. Based on pharmacodynamic studies, the MIC(90) for penicillin in Turkey should easily be exceeded with the use of penicillin G 3 mU QID. In vitro, susceptibility is generally greater to amoxicillin than to penicillin, with average amoxicillin MIC values approximately 1 dilution lower than those for penicillin. Amoxicillin's better pharmacodynamic/pharmacokinetic properties relative to penicillin make it a reasonable option for the treatment of CAP. In pharmacodynamic studies, amoxicillin 1 g TID achieved and maintained serum concentrations of 2 to 4 microg/mL for at least 40% of the dosing interval. A new formulation of amoxicillin/clavulanate given 2000/125 mg BID is expected to eradicate isolates of S pneumoniae at an amoxicillin MIC < or = 4 microg/mL.

CONCLUSIONS

Based on data from Turkish surveillance studies performed from 2000 onward, high-dose parenteral penicillin G and parenteral/oral amoxicillin may be initial choices for the empiric treatment of uncomplicated pneumococcal pneumonia in Turkey. If these agents cannot be used for any reason, other options include parenteral cefuroxime, ceftriaxone, cefotaxime, newer quinolones, macrolides, and telithromycin. Due to elevated rates of resistance in Turkey, trimethoprim-sulfamethoxazole and tetracyclines are not recommended for empiric use in these infections.

[Guidelines for the management of community pneumonia in adult who needs hospitalization]

Community acquired pneumonia is still an important health problem. In Spain the year incidence is 162 cases per 100,000 inhabitants with 53,000 hospital admission costing 115 millions of euros per year. In the last years there have been significant advances in the knowledge of: aetiology, diagnostic tools, treatment alternatives and antibiotic resistance. The Spanish Societies of Intensive and Critical Care (SEMICYUC), Infectious Diseases and Clinical Microbiology (SEIMC) and Pulmonology and Thoracic Surgery (SEPAR) have produced these evidence-based Guidelines for the management of community acquired pneumonia in Adults. The main objective is to help physicians to make decisions about this disease. The different points that have been developed are: aetiology, diagnosis, treatment and prevention.

Antimicrobial susceptibility patterns of Streptococcus pneumoniae in Mexico

The susceptibility to 14 beta-lactam and non-beta-lactam antimicrobial agents was evaluated for Streptococcus pneumoniae from patients with community-acquired respiratory infections in a Mexican medical center. Three hundred fifteen pneumococcal isolates obtained from patients between 1995 and 2001 were tested by the broth microdilution test. Fifty-two percent of the isolates were nonsusceptible to penicillin (minimal inhibitory concentration, >0.06 microg/mL). Penicillin-nonsusceptible isolates were more likely to exhibit resistance to cephalosporins, macrolides, ciprofloxacin, trimethoprim/sulfamethoxazole, chloramphenicol, and tetracycline when compared to penicillin-susceptible isolates. Ninety-three percent of the penicillin-nonsusceptible isolates were resistant to at least one other class of antimicrobials, in contrast to only 47% of the penicillin-susceptible strains (p < 0.0001). More than 90% of the tested isolates were susceptible to amoxicillin/clavulanate, ceftriaxone, levofloxacin, and gatifloxacin. Reduced susceptibility to penicillin was considered to be a reliable marker for the higher probability of multidrug resistance, thus requiring in vitro tests to guide chemotherapy or the choices of parenteral extended spectrum cephalosporins or newer respiratory quinolones.

Clinical Outcomes of Pneumococcal Pneumonia Caused by Antibiotic-Resistant Strains in Asian Countries: A Study by the Asian Network for Surveillance of Resistant Pathogens

To evaluate the clinical outcomes of pneumococcal pneumonia caused by antibiotic-resistant strains in Asian countries, we performed a prospective observational study of 233 cases of adult pneumococcal pneumonia in 9 Asian countries from January 2000 to June 2001. Among 233 isolates, 128 (55%) were not susceptible to penicillin (25.3% were intermediately susceptible, and 29.6% were resistant). Clinical severity of pneumococcal pneumonia was not significantly different between antibiotic-resistant and antibiotic-susceptible groups. Mortality rates among patients with pneumococcal pneumonia caused by penicillin-, cephalosporin-, or macrolide-resistant strains were not higher than those with antibiotic-susceptible pneumococcal pneumonia. Bacteremia and mechanical ventilation were significant risk factors for death, but any kind of antibiotic resistance was not associated with increased mortality due to pneumococcal pneumonia. Outcome of pneumococcal pneumonia was not significantly affected by drug resistance, and current antimicrobial regimens are mostly effective in the treatment of pneumococcal pneumonia, despite the widespread emergence of in vitro resistance.

Clinical relevance of antimicrobial resistance in the management of pneumococcal community-acquired pneumonia

Streptococcus pneumoniae remains the most common bacterial cause of community-acquired pneumonia, and these infections are associated with significant morbidity and mortality worldwide. A major concern is the increasing incidence of antibiotic resistance among pneumococcal isolates, which, in the case of certain of the antibiotic classes, has been associated with treatment failure. Yet despite multiple reports of infections with penicillin-resistant pneumococcal isolates, no cases of bacteriologic failure have been documented with the use of penicillin or ampicillin in the treatment of pneumonia caused by penicillin-resistant pneumococci. Current prevalence and levels of penicillin resistance among pneumococal isolates in most areas of the world do not indicate a need for substantial treatment changes with regard to the use of the penicillins. For infections with penicillin-sensitive strains, penicillin or an aminopenicillin in a standard dosage will still be effective for treatment. In the cases of strains with intermediate resistance, beta-lactam agents are still considered appropriate treatment, although higher dosages are recommended. Infections with isolates of high-level penicillin resistance should be treated with alternative agents such as the third-generation cephalosporins or the new antipneumococcal fluoroquinolones. In the case of the cephalosporins, pharmacodynamic/pharmacokinetic parameters help predict which of those agents are likely to be successful, and the less active agents should not be used. Debate continues in the literature with regard to the impact of macrolide resistance on the outcome of pneumococcal pneumonia, with some investigators providing evidence of an "in vivo-in vitro paradox," referring to discordance between reported in vitro resistance and clinical success of macrolides/azalide in vivo. However, several cases of macrolide/azalide treatment failure have been documented, and many clinicians recommend that these agents not be used on their own in areas with a high prevalence and levels of macrolide/azalide resistance. However, evidence is emerging to show beneficial effects on outcome with combination therapy, especially that of a beta-lactam agent and a macrolide given together to sicker, hospitalized patients with pneumococcal pneumonia. In an attempt to prevent the emergence of resistance, it has been recommended by some that the new fluoroquinolones not be used routinely as first-line agents in the treatment of community-acquired pneumonia; instead, they say, these agents should be reserved for patients who are allergic to the commonly used beta-lactam agents, for infections known to be or suspected of being caused by highly resistant strains, and for patients in whom initial therapy has failed.

Drug‐Resistant Pneumococcal Pneumonia: Clinical Relevance and Related Factors

A multicenter study of 638 cases of community-acquired pneumonia due to Streptococcus pneumoniae (SP-CAP) was performed to assess current levels of resistance. Of the pneumococcal strains, 35.7% had an minimum inhibitory concentration (MIC) of penicillin of > or =0.12 microg/mL (3 isolates had an MIC of 4 microg/mL), 23.8% had an MIC of erythromycin of 128 microg/mL, and 22.2% were multidrug resistant. Logistic regression determined that chronic pulmonary disease (odds ratio [OR], 1.44], human immunodeficiency virus infection (OR, 1.98), clinically suspected aspiration (OR, 2.12), and previous hospital admission (OR, 1.69) were related to decreased susceptibility to penicillin, and previous admission (OR, 1.89) and an MIC of penicillin of MIC > or =0.12 microg/mL (OR, 15.85) were related to erythromycin resistance (MIC, > or =1 microg/mL). The overall mortality rate was 14.4%. Disseminated intravascular coagulation, empyema, and bacteremia were significantly more frequent among patients with penicillin-susceptible SP-CAP. Among isolates with MICs of penicillin of > or =0.12 microg/mL, serotype 19 was predominant and was associated with a higher mortality rate. In summary, the rate of resistance to beta -lactams and macrolides among S. pneumoniae that cause CAP remains high, but such resistance does not result in increased morbidity.

Antibacterial resistance among children with community-acquired respiratory tract infections (PROTEKT 1999-2000)

OBJECTIVE

To determine the susceptibility of bacterial respiratory tract pathogens, isolated from children (0-12 years) as part of the global PROTEKT surveillance study (1999-2000), to a range of antibacterials, including the ketolide telithromycin.

METHODS

Minimum inhibitory concentrations of the antibacterials studied were determined at a central laboratory using the NCCLS microdilution broth method. Macrolide resistance mechanisms were detected by PCR.

RESULTS

Of 779 Streptococcus pneumoniae isolates worldwide, 43% were non-susceptible to penicillin (18% intermediate; 25% resistant) and 37% were resistant to erythromycin, with considerable intercountry variation. Eighteen per cent of 653 Haemophilus influenzae and >90% of 316 Moraxella catarrhalis isolates produced beta-lactamase. Of 640 Streptococcus pyogenes isolates, 10% were resistant to erythromycin, with considerable intercountry variation. All S. pneumoniae and 99.8% of H. influenzae isolates were susceptible to telithromycin using breakpoints proposed to the NCCLS (<or=1 and <or=4 mg/L, respectively). All M. catarrhalis and 97% of S. pyogenes and isolates were susceptible to <or=1 mg/L telithromycin.

CONCLUSIONS

Antibacterial resistance complicates the empirical treatment of respiratory tract infections in children and requires continued monitoring. Telithromycin may be a useful therapeutic alternative as it is highly active against strains exhibiting various resistance phenotypes.

The epidemiology of antibiotic resistance in Streptococcus pneumoniae and the clinical relevance of resistance to cephalosporins, macrolides and quinolones

Invasive non-meningeal pneumococcal infections remain a major cause of morbidity and mortality worldwide. The factors affecting the epidemiology and mortality of pneumococcal infections are discussed. The increase and spread of resistance to antimicrobial agents among pneumococci is a cause of concern to the clinician. There are links between the usage of antibacterial agents and the development of resistance. Resistance to penicillin and other beta-lactams has become widespread but this does not appear to have decreased the efficacy of some of these agents against non-meningeal infections. There is evidence that the good pharmacokinetic and pharmacodynamic features of the third generation cephalosporins (cefotaxime and ceftriaxone) contribute to their efficacy in vivo. New breakpoints for cefotaxime and ceftriaxone against non-meningeal pneumococcal isolates were proposed by the National Committee for Clinical Laboratory Standard (NCCLS, US), based on the clinical evidence of the efficacy of these drugs. In contrast there is increasing evidence that resistance to macrolides can lead to a poor clinical response. Fluoroquinolones have been widely used to treat respiratory tract infections among others, and pneumococcal resistance to these agents in vitro, although currently low, is increasing. There are reports that resistance to fluoroquinolones can develop during treatment and may be reflected in a lack of clinical response. Several clinical and epidemiological variables (e.g. prior antibiotic use) can be useful to identify patients at risk from infections with antibiotic-resistant pneumococci. These patients would be those who would benefit the most from a pneumococcal vaccination programme.

Pediatric invasive pneumococcal disease in a teaching hospital in Bangkok

BACKGROUND

Increased problems with drug-resistant Streptococcus pneumoniae (SP) and the dearth of epidemiologic and clinical information on invasive pneumococcal disease in children in Asia formed the basis for this study.

METHODS

A periodic retrospective review of the records of 0-15-year-old patients was conducted at a teaching hospital in Bangkok, during 1971-2000.

RESULTS

Infections with penicillin-non-susceptible SP (PNSSP) strains rapidly increased after they first appeared in 1988, and they accounted for 71% (29/41) of the total cases during 1996-2000. Of 137 patients, 74% were <60 months old, and 66% had an underlying condition. Infections included: bacteremia without focus 51; pneumonia 38; meningitis 35; peritonitis 13; and bone/joint infection 2. Two patients had two foci of infection. Eight of 10 episodes in patients with AIDS were bacteremic pneumonia. Median ages (range) in months for patients with and without an underlying condition were 24 (1-174) and 10 (0-160); and for the patients without an underlying condition they were: pneumonia 23 (4-156); bacteremia without focus 12 (0-160); and meningitis 7 (2-156). Case-fatality rates were 18% and 2% for patients with and without an underlying condition. The study also examined factors associated with PNSSP infection and death. During 1991-2000, 74% (43/58) of the total cases occurred from November to April, which are dry months.

CONCLUSIONS

This study population contained a high proportion with both an underlying condition and infection with PNSSP, and a moderately low proportion with bacteremia without focus. The disease was two to three times more common in dry months than in rainy months.

Invasive pneumococcal disease in Oxford, 1985-2001: a retrospective case series

AIMS

To describe a series of children with invasive pneumococcal disease (IPD).

METHODS

A review of patient records for children aged 0-18 years admitted to the John Radcliffe Hospital with IPD from 1985 to 2001. Social deprivation was measured by the Jarman index. The proportion of children with congenital abnormalities was compared with national data.

RESULTS

We identified 140 children with IPD; complete data were available for 136 children. The median age at diagnosis was 1.5 years. The social deprivation score of households of children with IPD was higher than that of the average Oxfordshire household (-2.5 v -7.3, p < 0.001). Forty four per cent of cases had at least one preceding health problem. The children with preceding health problems were significantly older than those with no preceding problems (median age 2.67 years, interquartile range 1.21 to 6.20 versus 1.11 years, interquartile range 0.51 to 2.21; p < 0.001). There was an increased risk of IPD for children with central nervous system malformations (OR = 99, 95% CI 31 to 236), congenital heart disease (OR = 62, 95% CI 24 to 131), and chromosomal abnormalities (OR = 32, 95% CI 6.6 to 96).

CONCLUSIONS

There is an increased risk of IPD associated with increased social deprivation; and also with central nervous system malformations, congenital heart disease, and chromosomal abnormalities.

Invasive pneumococcal infections: a clinical and microbiological analysis of 53 patients in Taiwan

OBJECTIVE

To track penicillin susceptibility among Streptococcus pneumoniae causing invasive diseases and to evaluate risk factors for antibiotic resistance.

METHODS

A retrospective study was performed in a medical center of all patients with invasive pneumococcal infections based on positive microbiological findings, confirmed by appropriate clinical and laboratory findings. MICs of penicillin and ceftriaxone were determined and interpreted by NCCLS methodology.

RESULTS

Fifty-three episodes of invasive S. pneumoniae infections (ISPI) among 22 children and 31 adults were identified. The disease patterns of ISPI were similar between children and adults, and the most common modes were pneumonia (70%) and primary bacteremia (23%). The rate of penicillin-nonsusceptible S. pneumoniae (PNSP) isolated from pediatric patients was higher than that in adult patients (95.5% vs. 54.8%, P < 0.001). This finding was correlated to prior antibiotic use that was more common in children (36.4%) than in adults (18.9%). The rate of penicillin-resistance among S. pneumoniae isolates (PRSP) was extremely high in this area: 45.5% from pediatric patients and 41.9% from adult patients. More adults (90.3%) with ISPI had major underlying diseases than children (4.5%). This may explain why adult patients tended to run an unfavorable outcome (mortality rate, 51.6% and 4.5% in adults and children, respectively), although most of the cases with empyema were children. None of the patients enrolled in this study received pneumococcal vaccination.

CONCLUSION

We suggest that vaccines be administered for young children and the elderly with major underlying diseases to prevent ISPI.

Clinical and microbiological epidemiology of Streptococcus pneumoniae bacteremia in eight French counties

OBJECTIVE

To describe the incidence of pneumococcal bacteremia not associated with infection of the central nervous system, investigate the susceptibility of bacterial isolates to beta-lactams, evaluate risk factors for antibiotic resistance, and determine factors predicting patient outcome.

METHODS

Over a period of 1 year, 919 Streptococcus pneumoniae isolates were collected from 919 patients with bacteremia in eight French counties. Their clinical and microbiological features were recorded. Univariate and multivariate analyses were used to determine risk factors for penicillin-non-susceptible pneumococcal bacteremia and predictors of fatal outcome.

RESULTS

Of the 919 patients in the study, 27% were infected with penicillin-non-susceptible pneumococci (PNSP): 17.8% of the isolates were intermediate to penicillin, 7.2% were resistant to penicillin, 16% were intermediate to amoxicillin, and 11% were intermediate to cefotaxime; no PNSP were resistant to either of the last two antibiotics. The most common PNSP serotypes isolated were 14 (41%) and 23 (24%). A statistically significant relationship between PNSP infection and age below 5 years or above 60 years in the different counties was observed by univariate and multivariate analysis. Gender, origin of bacteremia, co-morbidity, immunodeficiency, previous hospitalization and nosocomial infection were not predisposing factors associated with PNSP. The mortality rate was 20.6%: there was no increase in mortality among patients with PNSP bacteremia. Age was the strongest risk factor for mortality, but immunodeficiency also seemed to have had an impact on mortality. Clinical outcome was more closely related to clinical conditions than to the susceptibility status of S. pneumoniae.

CONCLUSION

Among cases of bacteremia, 27% were caused by PNSP, but this level varies according to the counties and the age of the patients. Infection-related mortality was high, but there was no increase related to penicillin G non-susceptibility of the infecting strain.

Lower respiratory tract infection in hospitalized children

OBJECTIVE

The aim of the present study was to investigate the aetiology and antibiotic-resistance patterns of community-acquired lower respiratory tract infection (LRTI) in 1999 and compare it with data from 1995 and 1988.

METHODOLOGY

A prospective observational study of LRTI in hospitalized children at KK Women's & Children's Hospital, Singapore, was undertaken.

RESULTS

A positive isolate was found in 58% of patients (671/1158), comprising viruses (n = 477, 41.2%), non-type B Haemophilus influenzae (n = 101, 8.7%), Streptococcus pneumoniae (n = 66, 5.7%), Mycoplasma pneumoniae (n = 92, 8%), Moraxella catarrhalis (n = 19, 1.6%) and other bacteria (n = 19, 1.6%). Mixed virus-bacteria (n = 104, 9%) infections were comprised mostly of virus-H. influenzae combinations. In 1999, S. pneumoniae resistance rates were penicillin 44.6% (17%, 1995), amoxycillin 3% (18%, 1995; MIC 0.5-2 microg/mL reclassified as susceptible in 1999), erythromycin 55% (30%, 1995), trimethoprim-sulfamethoxazole (TMP/SMX) 60% (23%, 1995). H. influenzaeresistance rates were amoxycillin 26.7% (38%, 1995), erythromycin 99% (37%, 1995), TMP/SMX 98% (37%, 1995). There were 15 cases of empyema of which seven were proven S. pneumoniae and there was one pneumococcal death (0.08%).

CONCLUSIONS

Pneumococcal pneumonia needs to be treated aggressively due to its high morbidity. Amoxycillin still remains useful for treating pneumococcus despite an increasing resistance to penicillin, erythromycin and TMP/SMX. Judicious use of antibiotics is needed to curb the increasing rate of antibiotic-resistance.

The era of antimicrobial resistance-implications for the clinical laboratory

The emergence of resistance to antimicrobial drugs in a range of bacterial pathogens of the respiratory tract creates a challenge for the clinical diagnostic laboratory. Resistance to macrolides among strains of Streptococcus pneumoniae has reached high levels in many countries. There are two main types of resistance mechanisms, one (MLSB phenotype) leading to high-level resistance and the other (M phenotype) resulting in a lower level of resistance. As there are indications that high-level resistance may have clinical relevance, it is important to be able to detect such strains. This is now possible with the erythromycin/clindamycin double disc diffusion test. Although resistance to beta-lactams has also increased, there is now evidence that some beta-lactams are still effective against isolates that have low-level resistance. In response to these observations, new breakpoints have now been introduced by the National Committee for Clinical Laboratory Standards (NCCLS) for amoxicillin, cefotaxime and ceftriaxone, which increase the percentage of pneumococcal isolates that can still be treated effectively with these agents. As a consequence of the increasing use of fluoroquinolones, resistance has now emerged to this group of compounds and this has been associated with clinical failures. Although standard minimum inhibitory concentration tests can detect strains with high levels of resistance (double step mutants) they are not reliable in detecting strains with a single mutation. This is important as there is increasing evidence that strains with a single mutation in the target topoisomerase are even more likely to develop a second mutation, leading to higher levels of resistance and thus probably, therapeutic failure. Because resistance to fluoroquinolones is currently low in the US, the NCCLS does not recommend that susceptibility testing with the newer respiratory fluoroquinolones be carried out routinely. However, since the respiratory fluoroquinolones have in fact become the first line of therapy for the treatment of community-acquired pneumonia, it may now be time to institute routine testing of clinical isolates of pneumococci to these agents. Simple techniques for the clinical diagnostic laboratory to enable these first-step mutants to be detected are urgently required.

Influence of macrolide susceptibility on efficacies of clarithromycin and azithromycin against Streptococcus pneumoniae in a murine lung infection model

We evaluated the activities of clarithromycin and azithromycin against 19 isolates of Streptococcus pneumoniae using a neutropenic lung infection model. The isolates included five susceptible isolates (clarithromycin and azithromycin MICs, </=0.12 micro g/ml), nine isolates exhibiting low-level, mefA-mediated resistance (clarithromycin and azithromycin MICs, 0.5 to 32 micro g/ml), and five isolates expressing high-level, ermB-mediated macrolide resistance (clarithromycin and azithromycin MICs, >/=64 micro g/ml). Infected mice were administered either saline (control), clarithromycin (4, 40, or 200 mg/kg of body weight twice daily or 200 mg/kg once daily), or azithromycin (4, 40, or 200 mg/kg once daily or 40 mg/kg twice daily) by oral gavage for 72 h. Mortality was assessed at regular intervals for 10 days, and survival in each group was compared to that of untreated controls. Animals infected with susceptible isolates demonstrated significant improvement in survival compared to the controls following treatment with either agent at doses of >/=40 mg/kg. In contrast, none of the regimens improved the survival of animals infected with isolates exhibiting high-level macrolide resistance. Among mice infected with strains expressing low-level resistance, significant improvement in survival compared to the controls was noted among isolates treated with clarithromycin at 40 (seven of nine isolates) and 200 (nine of nine isolates) mg/kg twice a day and with azithromycin at 40 (one of nine isolates) and 200 (three of nine isolates) mg/kg once a day. Animals infected with isolates of S. pneumoniae exhibiting low-level, mefA-mediated macrolide resistance responded to treatment with clarithromycin at rates similar to those observed among mice infected with fully susceptible isolates.

A critical assessment of published guidelines and other decision-support systems for the antibiotic treatment of community-acquired respiratory tract infections

Guidelines are an important means by which professional associations and governments have sought to improve the quality and cost-effectiveness of disease management for infectious diseases. Prescribing of initial antibiotic therapy for community-acquired respiratory tract infections (RTIs) is primarily empiric and physicians may often have a limited appreciation of bacterial resistance. Recent guidelines for managing RTIs have adopted a more evidence-based approach. This process has highlighted important gaps in the existing knowledge base, e.g. concerning the impact of resistance on the effectiveness of oral antibiotics for outpatient community-acquired pneumonia and the level of resistance that should prompt a change in empiric prescribing. In upper RTIs, the challenge is to identify patients in whom antibiotic therapy is warranted. Concentrated, sustained efforts are needed to secure physicians' use of guidelines. The information should be distilled into a simple format available at the point of prescribing and supported by other behavioral change techniques (e.g. educational outreach visits). Advances in information technology offer the promise of more dynamic, computer-assisted forms of guidance. Thus, RTI prescribing guidelines and other prescribing support systems should help control bacterial resistance in the community. However, their effect on resistance patterns is largely unknown and there is an urgent need for collaborative research in this area. Rapid, cost-effective diagnostic techniques are also required and new antibiotics will continue to have a role in disease management.

The battle against emerging antibiotic resistance: should fluoroquinolones be used to treat children?

Inappropriate use of antibiotic drugs in humans and animals has led to widespread resistance among microbial pathogens. Resistance is the phenotypic expression corresponding to genetic changes caused by either mutation or acquisition of new genetic information. In some cases, multidrug resistance occurs. Streptococcus pneumoniae is one of the most important respiratory pathogens, playing a major role in both upper and lower respiratory tract infections. Pneumococcal resistance to antimicrobials may be acquired by means of horizontal transfer followed by homologous recombination of genetic material from the normal flora of the human oral cavity or by means of mutation. Resistance to penicillins and macrolides has been increasing for some time, but, recently, fluoroquinolone resistance has become an issue as well. We are concerned that, if fluoroquinolones are approved for use in children, their widespread use will result in rapid emergence of pneumococcal resistance, because children are more often colonized in the nasopharynx with high-density populations of pneumococci than are adults.

The effect of cephalosporin resistance on mortality in adult patients with nonmeningeal systemic pneumococcal infections

PURPOSE

To evaluate the clinical relevance of cephalosporin (ceftriaxone/cefotaxime) resistance among patients with nonmeningeal systemic pneumococcal infection.

SUBJECTS AND METHODS

From January 1994 to October 2000, we prospectively studied 522 episodes of nonmeningeal systemic pneumococcal infections (448 pneumonias) in 499 adults who were treated according to hospital guidelines. In vitro antibiotic susceptibility, as the minimum inhibitory concentration (MIC), was determined by microdilution method. The MIC methods and breakpoints (cutoffs) were established by the National Committee for Clinical Laboratory Standards.

RESULTS

Of the 522 pneumococcal strains, 413 strains (79%) were susceptible to ceftriaxone/cefotaxime, MIC < or =0.5 microg/mL; 79 (15%) were intermediate, MIC = 1 microg/mL; and 30 (6%) were resistant, MIC = 2 microg/mL. After adjusting for several variables, including pneumococcal serogroups/serotypes, infections due to nonsusceptible (intermediate and resistant) pneumococcal strains were independently associated with prior antibiotic therapy, with an odds ratio of 5.9 (95% confidence interval: 2.6 to 13.6). Thirty-day mortality among the 185 patients who were treated with ceftriaxone (1 g/d) or cefotaxime (1.5 g every 8 hours) did not differ by cephalosporin susceptibility: 18% (26/148) among those with susceptible organisms, 13% (3/24) with intermediate organisms, and 15% (2/13) in resistant cases (P = 0.81).

CONCLUSION

Ceftriaxone or cefotaxime were effective in treating patients with nonmeningeal systemic pneumococcal infections caused by strains with MIC < or =2 microg/mL. These results support the newly established ceftriaxone/cefotaxime MIC breakpoints (cutoffs) for nonmeningeal pneumococcal infections.

Clinical aspects and cost of invasive Streptococcus pneumoniae infections in children: resistant vs. susceptible strains

Invasive Streptococcus pneumoniae infections in children are associated with serious consequences in terms of morbidity and mortality. The main objective of the study was to determine if invasive infections caused by penicillin-resistant Streptococcus pneumoniae (PRSP) differed in clinical presentation, outcome, risk factors, or cost from those caused by penicillin-susceptible strains (PSSP) in children. All patients aged 18 or less with invasive Streptococcus pneumoniae infections admitted to two teaching hospitals in Montreal between 1989 and 1998 were included in the study. We present a case-control study in which for each index case of PRSP, 3 controls with PSSP infections were matched for age, sex, and site of infection. One hundred and forty-four patients were included in the analysis (36 cases, 108 controls). There was no difference between the two groups in terms of initial clinical presentation (vital signs, laboratory results) or total length of stay. Mortality was 2.7% in both groups. Hospital antibiotic cost was higher in the PRSP group (211 Canadian dollars (CAD) vs. 74 CAD; P=0.02). Antibiotic consumption in the preceding month was significantly associated with PRSP infection. Underlying diseases or day-care attendance were not shown to be significant risk factors for acquiring invasive PRSP infection. There were no differences between invasive infections caused by PRSP and PSSP in terms of clinical presentation, morbidity or mortality in a paediatric population.

Emerging resistance to antibiotics against respiratory bacteria: impact on therapy of community-acquired pneumonia in children

Perhaps because of its etiologic complexity, community-acquired pneumonia (CAP) in infants and children remains a significant problem worldwide. Over the last few years, difficulties related to CAP treatment in children have greatly increased because of the emergence of resistance to the most widely used antibiotics against some of the bacterial pathogens involved in the development of the disease. There are few data describing the impact of antibiotic resistance on clinical outcomes in CAP, but many experts believe that the clinical impact is limited. We here discuss the prevalence of different etiologic agents in CAP of children, the diagnostic criteria, problems related to antibiotic resistance, therapeutic strategies, and future implications.

Appropriate use of antimicrobials for drug-resistant pneumonia: focus on the significance of beta-lactam-resistant Streptococcus pneumoniae

The beta-lactam antibiotics (penicillins and cephalosporins) are commonly prescribed for the treatment of community-acquired pneumonia. However, Streptococcus pneumoniae, the most common etiologic agent of community-acquired pneumonia, has become increasingly resistant to beta-lactams over the past decade. The results of several studies suggest that penicillins remain effective for streptococcal pneumonia when the infecting pathogen has a minimal inhibitory concentration (MIC) </=2 microgram/mL, presumably because the pharmacokinetic and pharmacodynamic parameters associated with current dosing regimens are still sufficient. However, when the MIC >/=4 microgram/mL, increased rates of mortality (for patients who survive their first 4 days of hospitalization) may occur. Currently, 3.5%-7.8% of S. pneumoniae clinical isolates have MICs that fall in this latter class, but these rates may rise in the future. The clinical relevance of in vitro resistance may be related to at least 3 factors: concordance of antimicrobial therapy, severity of illness, and virulence.

Clinical outcomes of bacteremic pneumococcal pneumonia in the era of antibiotic resistance

Limited data are available about the impact of antimicrobial resistance on clinical outcomes in cases of pneumococcal pneumonia. This was studied in 146 persons hospitalized with invasive pneumonia due to Streptococcus pneumoniae (minimum inhibitory concentration of cefotaxime, > or = .25 microg/mL) who were identified through population-based active surveillance for the period of November 1994 through April 1996. Compared with matched control subjects who had infection with more-susceptible S. pneumoniae, the proportion of subjects who died or who were admitted to an intensive care unit did not differ significantly. Multivariable analysis showed no significant contribution of antimicrobial resistance to mortality or the requirement for care in an intensive care unit. The ability to detect an effect of antimicrobial resistance on these important outcome measures may have been influenced by aggressive multidrug empirical therapy in this group of hospitalized patients. Factors other than resistance, such as severity of illness at presentation and advance directive status ("do not resuscitate" orders), appear to have a stronger influence on pneumococcal pneumonia outcomes.

Pneumococcal meningitis in children: relationship of antibiotic resistance to clinical characteristics and outcomes

BACKGROUND

The relationship of antibiotic susceptibility to clinical outcome in children with pneumococcal meningitis is uncertain. Previous studies have been limited by inclusion of relatively few patients infected with nonsusceptible pneumococci and inconsistent use of empiric vancomycin.

METHODS

Medical records of 86 children with culture-confirmed pneumococcal meningitis at a single institution from October, 1991, to October, 1999, were retrospectively reviewed, and differences in presentation and outcome based on antibiotic susceptibility of pneumococcal isolates were assessed.

RESULTS

Of 86 isolates 34 were nonsusceptible to penicillin (12 resistant). Of 60 isolates for which cefotaxime susceptibility data were available, 17 were nonsusceptible (12 resistant). Antibiotic susceptibility was not significantly associated with death, intensive care unit admission, mechanical ventilation, focal neurologic deficits, seizures, secondary fever, abnormal neuroimaging studies or hospital days. Children with penicillin-resistant isolates had significantly higher median blood leukocyte counts (24,100/microliter vs. 15,700/microliter, P = 0.03) and lower median CSF protein concentrations (85 mg/dl vs. 219 mg/dl, P = 0.04), were more likely to have a CSF glucose concentration of > or = 50 mg/dl (7 of 11 vs. 15 of 68, P = 0.009) and had lower rates of sensorineural hearing loss (1 of 8 vs. 25 of 40, P = 0.02) than children with isolates that were not resistant to penicillin. Children with cefotaxime-nonsusceptible isolates had an increased median duration of primary fever compared with those with nonsusceptible strains (6 days vs. 3.5 days, P = 0.02).

CONCLUSIONS

In children with pneumococcal meningitis, penicillin resistance was associated with a reduced risk of hearing loss, while cefotaxime resistance was associated with a longer duration of fever. Other outcome measures were not significantly influenced by the antibiotic susceptibility of pneumococcal isolates.

Outcome of invasive infections outside the central nervous system caused by Streptococcus pneumoniae isolates nonsusceptible to ceftriazone in children treated with beta-lactam antibiotics

OBJECTIVE

To determine the outcome of children treated primarily with beta-lactam antibiotics for a systemic infection outside the central nervous system (CNS) caused by isolates of Streptococcus pneumoniae nonsusceptible to ceftriaxone (MIC > or = 1.0 microg/ml).

DESIGN

Retrospective review of the medical records of children identified prospectively with invasive infections outside of the CNS caused by isolates of S. pneumoniae that were not susceptible to ceftriaxone between September, 1993, and August, 1999. A subset of this group treated primarily with beta-lactam antibiotics was analyzed for outcome.

PATIENTS

Infants and children with pneumococcal infections cared for at eight children's hospitals.

RESULTS

Among 2,100 patients with invasive infections outside the CNS caused by S. pneumoniae, 166 had isolates not susceptible to ceftriaxone. One hundred patients treated primarily with beta-lactam antibiotics were identified. From this group 71 and 14 children had bacteremia alone or with pneumonia, respectively, caused by strains with an MIC of 1.0 microg/ml. Bacteremia or pneumonia caused by isolates with a ceftriaxone MIC > or = 2.0 microg/ml occurred in 6 and 5 children, respectively. Three children with septic arthritis and 1 with cellulitis had infections caused by strains with an MIC to ceftriaxone of 1.0 microg/ml. Most were treated with parenteral ceftriaxone, cefotaxime or cefuroxime for one or more doses followed by an oral antibiotic. All but one child were successfully treated. The failure occurred in a child with severe combined immune deficiency and bacteremia (MIC = 1.0 microg/ml) who remained febrile after a single dose of ceftriaxone followed by 12 days of cefprozil.

CONCLUSION

Ceftriaxone, cefotaxime or cefuroxime are adequate to treat invasive infections outside the CNS caused by pneumococcal isolates with MICs up to 2.0 microg/ml, a concentration currently considered resistant for these antibiotics by National Committee for Clinical Laboratory Standards breakpoints.

Standard case management of pneumonia in hospitalized children in Uruguay, 1997 to 1998

OBJECTIVE

To report the results of the use of antimicrobial guidelines for the management of children with community-acquired bacterial pneumonia.

METHODS

Admittance and discharge criteria and algorithms for diagnosis and treatment were established. The decision to treat with antibiotics was based on radiologic findings in pneumonia with pulmonary consolidation and left to the attending physician's criteria in the remaining cases. The use of antibiotics was limited to penicillin and derivatives (ampicillin, amoxicillin) and macrolides.

RESULTS

Of the 1163 children treated as bacterial pneumonia, hospitalized in public and private health facilities in Montevideo from September, 1997, through September, 1998, standard case management was applied in 1082 (93%). Age distribution was: <1 month, 1%; between 1 and 11 months, 29%; between 1 and 5 years, 50%; >5 years, 20%. Chest radiography showed evidence of pulmonary consolidation in 843 children (73%). Bacteria were detected in blood culture and/or pleural fluid of 57 children (5%). In 51 the identified microorganism was Streptococcus pneumoniae, susceptible to penicillin in 30, intermediate in 6 and resistant in 5 (maximum MIC, 4 microg/ml); in 10 cases etiologic diagnosis was made by antigen detection. Empyema was present in 62 children (5.3%); 38 (3.27%) required treatment in an intensive care unit; and 5 (0.4%) died.

CONCLUSIONS

Compliance with standard case management was highly satisfactory. Outcome of children treated with penicillin and derivatives was good, including children with empyema and pneumatocele and two patients with penicillin-resistant S. pneumoniae. At the present time S. pneumoniae resistant to penicillin is not an important problem in children with pneumonia in Uruguay. Surveillance of identified microorganisms and their antimicrobial susceptibility must continue.

Increasing prevalence of multidrug-resistant Streptococcus pneumoniae in the United States

BACKGROUND

The emergence of drug-resistant strains of bacteria has complicated treatment decisions and may lead to treatment failures.

METHODS

We examined data on invasive pneumococcal disease in patients identified from 1995 to 1998 in the Active Bacterial Core Surveillance program of the Centers for Disease Control and Prevention. Pneumococci that had a high level of resistance or had intermediate resistance according to the definitions of the National Committee for Clinical Laboratory Standards were defined as "resistant" for this analysis.

RESULTS

During 1998, 4013 cases of invasive Streptococcus pneumoniae disease were reported (23 cases per 100,000 population); isolates were available for 3475 (87 percent). Overall, 24 percent of isolates from 1998 were resistant to penicillin. The proportion of isolates that were resistant to penicillin was highest in Georgia (33 percent) and Tennessee (35 percent), in children under five years of age (32 percent, vs. 21 percent for persons five or more years of age), and in whites (26 percent, vs. 22 percent for blacks). Penicillin-resistant isolates were more likely than susceptible isolates to have a high level of resistance to other antimicrobial agents. Serotypes included in the 7-valent conjugate and 23-valent pneumococcal polysaccharide vaccines accounted for 78 percent and 88 percent of penicillin-resistant strains, respectively. Between 1995 and 1998 (during which period 12,045 isolates were collected), the proportion of isolates that were resistant to three or more classes of drugs increased from 9 percent to 14 percent; there also were increases in the proportions of isolates that were resistant to penicillin (from 21 percent to 25 percent), cefotaxime (from 10 percent to 15 percent), meropenem (from 10 percent to 16 percent), erythromycin (from 11 percent to 16 percent), and trimethoprim-sulfamethoxazole (from 25 percent to 29 percent). The increases in the frequency of resistance to other antimicrobial agents occurred exclusively among penicillin-resistant isolates.

CONCLUSIONS

Multidrug-resistant pneumococci are common and are increasing. Because a limited number of serotypes account for most infections with drug-resistant strains, the new conjugate vaccines offer protection against most drug-resistant strains of S. pneumoniae.

Clinical outcome of invasive infections in children caused by highly penicillin-resistant Streptococcus pneumoniae compared with infections caused by penicillin-susceptible strains

BACKGROUND

In this report based on data from the Institutional Surveillance System during 1994-1998, we document the continuing emergence of drug-resistant Streptococcus pneumoniae strains at the Hospital Infantil de Mexico Federico Gómez in Mexico City.

METHODS

We evaluate the clinical course of 49 invasive pneumococcal infection outside the central nervous system (CNS) by a number of factors including the site, severity, and place where the infection was acquired, the underlying health of the patient, and the adequacy of antimicrobial therapy.

RESULTS

An underlying illness was present in 21 of 49 (43%) patients, 37 (75%) patients had taken previous antimicrobial therapy, and 25% of the infections were nosocomially acquired. Overall, 25 of 49 (51%) of the pneumococcal strains tested were pencillin-resistant; strains with the highest resistance to penicillin were also resistant to cephalosporins. Twenty-two percent of all strains were considered to be multidrug-resistant. Eleven of 25 penicillin-resistant strains were identified as multidrug-resistant, i.e., to erythromycin, TMP/SMX, and chloramphenicol. Ten serotypes accounted for 88% of the isolates, the most frequent serotypes being 23F, 14, 19V, 6A, and 6B. The overall case-fatality rate was 37% (18 of 49), with most deaths occurring within 3-5 days after antibiotic therapy was initiated. There was no difference in the case fatality rate between children with penicillin-nonsusceptible and penicillin-susceptible pneumococcal infections; instead; case-fatality rate correlated with severity of illness on admission and presence of underlying disease.

CONCLUSIONS

Characterizing groups at risk for invasive pneumococcal disease could aid in the development of preventive programs and increase the benefits from wide use of future conjugated vaccines.