Three-year multicenter surveillance of systemic pneumococcal infections in children

Streptococcus Pneumoniae-Associated Hemolytic Uremic Syndrome in the Era of Pneumococcal Vaccine

Streptococcus pneumoniae-associated hemolytic uremic syndrome (Sp-HUS) is a serious complication of invasive pneumococcal disease that is associated with increased mortality in the acute phase and morbidity in the long term. Recently, Sp-HUS definition has undergone revision and cases are categorized as definite, probable, and possible, based on less invasive serological investigations that evaluate Thomsen-Friedenreich crypt antigen (T-antigen) activation. In comparison to the pre-vaccine era, Sp-HUS incidence seems to be decreasing after the introduction of 7-serotype valence and 13-serotype valence pneumococcal vaccines in 2000 and 2010, respectively. However, Sp-HUS cases continue to occur secondary to vaccine failure and emergence of non-vaccine/replacement serotypes. No single hypothesis elucidates the molecular basis for Sp-HUS occurrence, although pneumococcal neuraminidase production and formation of T-antigen antibody complexes on susceptible endothelial and red blood cells continues to remain the most acceptable explanation. Management of Sp-HUS patients remains supportive in nature and better outcomes are being reported secondary to earlier recognition, better diagnostic tools and improved medical care. Recently, the addition of eculizumab therapy in the management of Sp-HUS for control of dysregulated complement activity has demonstrated good outcomes, although randomized clinical trials are awaited. A sustained pneumococcal vaccination program and vigilance for replacement serotypes will be the key for persistent reduction in Sp-HUS cases worldwide.

Typical and Atypical Hemolytic Uremic Syndrome in the Critically Ill

Hemolytic uremic syndrome is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome have a similar clinical presentation. Diagnostic needs to be prompt to decrease mortality, because identifying the different disorders can help to tailor specific, effective therapies. However, diagnosis is challenging and morbidity and mortality remain high, especially in the critically ill population. Development of clinical prediction scores and rapid diagnostic tests for hemolytic uremic syndrome based on mechanistic knowledge are needed to facilitate early diagnosis and assign timely specific treatments to patients with hemolytic uremic syndrome variants.

Invasive pneumococcal infections in children following transplantation in the pneumococcal conjugate vaccine era

BACKGROUND

Pediatric recipients of hematopoietic stem cell and solid organ transplants are at increased risk of invasive pneumococcal infections (IPI). Data on IPI in this population are scarce. To our knowledge, this is the first study describing the epidemiology of IPI among pediatric transplant recipients in the pneumococcal conjugate vaccine (PCV) era.

METHODS

We identified transplant recipients with IPI at 8 children's hospitals in the U.S. from our surveillance database (2000-2014). Pneumococcal isolates were collected prospectively. Serotyping and antibiotic susceptibility were performed in a central laboratory. Categorical variables were analyzed by Fisher's exact test and continuous variables with nonparametric tests. Indirect cohort study design was used to calculate vaccine effectiveness.

RESULTS

We identified 65 episodes of IPI in transplant recipients. Recurrent IPI was observed in 10% of transplant recipients. The IPI crude incidence rate in solid organ transplant recipients was higher than in the general population. Most IPI episodes occurred >6 months after transplantation. Bacteremia and pneumonia were the most common presentations. Meningitis was unusual. No case fatalities were observed. Serotype 19A was the most common serotype (n=10), followed by 6C (n=7). In 2010-2014, 37% of IPI was caused by PCV13 serotypes. Four cases of vaccine breakthrough were identified. Most isolates were susceptible to penicillin and ceftriaxone. Pneumococcal conjugate and polysaccharide immunization rates were low.

CONCLUSION

Pediatric transplant recipients remain at increased risk of IPI in the vaccine era. Most cases presented as a late post-transplant infection. The interval between transplantation and IPI may allow adequate time for pneumococcal immunization.

Emergence of Multidrug-Resistant Pneumococcal Serotype 35B among Children in the United States

Streptococcus pneumoniae serotype 35B is a nonvaccine serotype associated with high rates of penicillin nonsusceptibility. An increase in the proportion of multidrug-resistant (MDR) 35B isolates has recently been reported. The genetic events contributing to the emergence of MDR serotype 35B are unknown. The sequence type (ST) composition of 78 serotype 35B isolates obtained from pediatric patients with invasive pneumococcal disease from 1994 to 2014 and 48 isolates from pediatric patients with otitis media (noninvasive) from 2011 to 2014 was characterized by multilocus sequence typing (MLST). The most common STs were ST558 (69.2%), ST156 (10.3%), and ST452 (3.8%). Two major clonal complexes (CC), CC558 and CC156, were identified by eBURST analysis. Overall, 91% (71/78) of isolates were penicillin nonsusceptible and 16.7% (13/78) were MDR. Among all invasive serotype 35B isolates, MDR isolates increased significantly, from 2.9% (1/35) to 27.9% (12/43) (P = 0.004), after the 13-valent pneumococcal conjugate vaccine (PCV13) was introduced. All CC156 isolates were identified after the introduction of PCV13 (0/35 [0%] before versus 9/43 [20.9%] after; P = 0.003) and were MDR. All CC156 isolates had similar antimicrobial susceptibility patterns; in contrast, high variability in antimicrobial susceptibility was observed among CC558 isolates. The distributions of CC558 and CC156 among invasive and noninvasive isolates were not different. The increased prevalence of MDR serotype 35B after the introduction of PCV13 was directly associated with the emergence of ST156. Genotyping suggests that capsular switching has occurred between MDR vaccine serotypes belonging to ST156 (e.g., 9V, 14, and 19A) and serotype 35B.

Impact of round-the-clock CSF Gram stain on empirical therapy for suspected central nervous system infections

The impact of round-the-clock cerebrospinal fluid (CSF) Gram stain on overnight empirical therapy for suspected central nervous system (CNS) infections was investigated. All consecutive overnight CSF Gram stains between 2006 and 2011 were included. The impact of a positive or a negative test on empirical therapy was evaluated and compared to other clinical and biological indications based on institutional guidelines. Bacterial CNS infection was documented in 51/241 suspected cases. Overnight CSF Gram stain was positive in 24/51. Upon validation, there were two false-positive and one false-negative results. The sensitivity and specificity were 41 and 99 %, respectively. All patients but one had other indications for empirical therapy than Gram stain alone. Upon obtaining the Gram result, empirical therapy was modified in 7/24, including the addition of an appropriate agent (1), addition of unnecessary agents (3) and simplification of unnecessary combination therapy (3/11). Among 74 cases with a negative CSF Gram stain and without formal indication for empirical therapy, antibiotics were withheld in only 29. Round-the-clock CSF Gram stain had a low impact on overnight empirical therapy for suspected CNS infections and was associated with several misinterpretation errors. Clinicians showed little confidence in CSF direct examination for simplifying or withholding therapy before definite microbiological results.

Impact of the 13-Valent Pneumococcal Conjugate Vaccine on Pneumococcal Meningitis in US Children

BACKGROUND

The impact of 13-valent pneumococcal conjugate vaccine (PCV13) on pneumococcal meningitis (PM) in US children is unknown. We compared the serotype distribution, antibiotic susceptibility, hospital course, and outcomes of children with PM 3 years before and 3 years after the introduction of PCV13.

METHODS

We identified patients ≤ 18 years of age with PM at 8 children's hospitals in the United States. Pneumococcal isolates were collected prospectively. Serotyping and antibiotic susceptibility were performed in a central laboratory. Clinical data were abstracted from medical records. Patients were divided into 3 subgroups: pre-PCV13 (2007-2009), transitional year (2010), and post-PCV13 (2011-2013). Categorical variables were analyzed by the χ(2) test and continuous variables by the Mann--Whitney U test.

RESULTS

During the study period, 173 of 1207 episodes (14%) of invasive pneumococcal disease were identified as PM; 76 of 645 (12%) were during 2007-2009 and 69 of 394 (18%) during 2011-2013 (50% increase; P = .03). The proportion of PCV13 serotype cases decreased from 54% in 2007-2009 to 27% in 2011-2013 (P = .001). Non-PCV13 serotype cases represented 73% of the isolates in 2011-2013. Isolates with ceftriaxone minimum inhibitory concentration ≥ 1 µg/mL decreased (13% to 3%) from 2007-2009 to 2011-2013 (P = .03). No significant differences were identified for hospital course or outcome, with the exception that a greater proportion of patients had subdural empyema and hemiparesis in 2011-2013.

CONCLUSIONS

After the introduction of PCV13, the number of cases of PM in children remained unchanged compared with 2007-2009, although the proportion of PCV13 serotypes decreased significantly. Serotype 19A continued to be the most common serotype in 2011-2013. Antibiotic resistance decreased significantly. Morbidity and case-fatality rate due to PM remain substantial.

Immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine administered to older infants and children naïve to pneumococcal vaccination

BACKGROUND

Streptococcus pneumoniae infections are a major cause of morbidity and mortality in children <5 years old worldwide. To increase serotype coverage globally, a 13-valent pneumococcal conjugate vaccine (PCV13) has been developed and approved in many countries worldwide.

OBJECTIVE

Assess the safety and immunogenicity of PCV13 in healthy older infants and children naïve to previous pneumococcal vaccination.

METHODS

This was a phase 3, open-label, multicenter study conducted in Polish children (N=354) who were vaccinated according to 3 age-appropriate catch-up schedules: Group 1 (aged 7 to <12 months) received two PCV13 doses with a booster at 12-16 months of age; Group 2 (aged 12 to <24 months) received two vaccine doses only; and Group 3 (aged 24 to <72 months) received a single dose of PCV13. Statistical analyses were descriptive. The proportion of immunological "responders" achieving serotype-specific antipneumococcal polysaccharide concentrations ≥0.35μg/mL, 1-month after the last dose of vaccine, was determined for each vaccine serotype. In addition, antipolysaccharide immunoglobulin (Ig) G geometric mean concentrations (GMCs) were calculated. Safety assessments included systemic and local reactions, and adverse events.

RESULTS

The proportion of immunological responders was ≥88% across groups for all serotypes. Antipolysaccharide IgG GMCs were generally similar across groups. Each schedule elicited immune response levels against all 13 serotypes comparable to or greater than levels previously reported in infants after a 3-dose series. The 3 catch-up schedules had similar tolerability and safety profiles; a trend was present towards greater local tenderness with increasing age and subsequent dose administration.

CONCLUSIONS

Immunological responses and safety results support the use of PCV13 for catch-up schedules in older infants and children naïve to pneumococcal vaccination.

Emergence of Streptococcus pneumoniae serogroups 15 and 35 in nasopharyngeal cultures from young children with acute otitis media

BACKGROUND

Surveillance of children with acute otitis media (AOM) for nasopharyngeal colonization with Streptococcus pneumoniae before, during and after the introduction of 7-valent pneumococcal conjugate vaccine (PCV7) indicated the near-complete elimination of PCV7 strains and the emergence of pneumococcal serotype 19A.

METHODS

To determine effects of the introduction of 13-valent pneumococcal conjugate vaccine (PCV13) on pneumococcal nasopharyngeal colonization, we obtained nasopharyngeal cultures from 228 children 6 through 23 of age months presenting with a new episode of AOM during 2012 and 2013 and enrolled in an ongoing clinical trial of antimicrobial efficacy. All children had received at least 2 doses of PCV13. The S. pneumoniae isolates were subjected to serotyping and testing for antimicrobial susceptibility. We compared the findings with results obtained in 3 earlier studies.

RESULTS

We found nasopharyngeal colonization with S. pneumoniae in 113 (50%) of the children with AOM. PCV7 and PCV13 serotypes accounted for 2% and 12%, respectively, of the pneumococcal isolates. Of the 14 PCV13 isolates, 8 were serotype 19A. Nonvaccine serotypes accounted for 69% of the isolates. Most frequently occurring were subtypes of serotype 15 (23%) and serotype 35B (9%). Overall, 33% of the isolates were penicillin nonsusceptible, a proportion not significantly different from proportions found in our 3 earlier studies (26%, 36% and 37%, respectively). Serotypes 15 and 35B accounted for 51% of penicillin-nonsusceptible isolates.

CONCLUSIONS

Expansion of contents of pneumococcal vaccine administered to children is followed by not-fully-predictable changes in nasopharyngeal pneumococcal colonization. Continued surveillance is required to help inform future vaccine development.

A prospective multicenter study of microbiologically defined infections in pediatric cancer patients with fever and neutropenia: Swiss Pediatric Oncology Group 2003 fever and neutropenia study

BACKGROUND

Fever and neutropenia (FN) often complicate anticancer treatment and can be caused by potentially fatal infections. Knowledge of pathogen distribution is paramount for optimal patient management.

METHODS

Microbiologically defined infections (MDI) in pediatric cancer patients presenting with FN by nonmyeloablative chemotherapy enrolled in a prospective multicenter study were analyzed. Effectiveness of empiric antibiotic therapy in FN episodes with bacteremia was assessed taking into consideration recently published treatment guidelines for pediatric patients with FN.

RESULTS

MDI were identified in a minority (22%) of pediatric cancer patients with FN. In patients with, compared with patients without MDI, fever [median, 5 (interquartile range: 3-8) vs. 2 (interquartile range: 1-3) days, P < 0.001] and hospitalization [10 (6-14) vs. 5 (3-8) days, P < 0.001] lasted longer, transfer to the intensive care unit was more likely [13 of 95 (14%) vs. 7 of 346 (2.0%), P < 0.001], and antibiotics were given longer [10 (7-14) vs. 5 (4-7) days, P < 0.001]. Empiric antibiotic therapy in FN episodes with bacteremia was highly effective if not only intrinsic and reported antimicrobial susceptibilities were considered but also the purposeful omission of coverage for coagulase-negative staphylococci and enterococci was taken into account [81% (95% confidence interval: 68-90) vs. 96.6% (95% confidence interval: 87-99.4), P = 0.004].

CONCLUSIONS

MDI were identified in a minority of FN episodes but they significantly affected management and the clinical course of pediatric cancer patients. Compliance with published guidelines was associated with effectiveness of empiric antibiotic therapy in FN episodes with bacteremia.

Emergency department epidemiology of pneumococcal bacteremia in children since the institution of widespread PCV7 vaccination

BACKGROUND

The heptavalent pneumococcal conjugate vaccine (PCV7) has produced a shift in the epidemiology of invasive infections from Streptoccoccus pneumoniae.

OBJECTIVE

Our aim was to determine the temporal changes in pneumococcal bacteremia (Streptococcus pneumoniae bacteremia [SPB]) in the emergency department (ED) since the introduction of PCV7.

METHODS

This was a retrospective cohort study of children 0-18 years with SPB evaluated from 1998-2009 in a tertiary-care pediatric ED. The primary outcome was annual proportion of children with SPB from PCV7 serotypes (ie, 4, 6B, 9V, 14, 18C, 19F, and 23F) and nonvaccine serotypes (NVT). Rates of SPB (per 10,000 ED visits) were calculated. SPB was analyzed by time period: before October 2000 was considered "pre-PCV7," November 2000 to October 2003 was considered "peri-PCV7," and after November 2003 was "post-PCV7." Febrile young children (FYC) were defined as children age <36 months and fever without source.

RESULTS

A total of 201 episodes of SPB occurred during the study, with a median age of 20.3 months (interquartile range 10.7-49.5 months; range 1.6-215.4 months); 56.7% were male and 69.7% were African American. SPB from PCV7 serotypes decreased more than fourfold, from 82.2% pre-PCV7 to 19.5% peri- and post-PCV7. Most SPB was from NVT serotype 19A (31.3%) peri- and post-PCV7. Annual rates of SPB were 4.01/10,000 ED visits pre-PCV7, decreasing to 2.10 peri-PCV7, and 1.75 post-PCV7. Among the 56 (27.8%) FYC with SPB, NVT were responsible for 11.5% of SPB pre-PCV7, and increased to 80.0% peri- and post-PCV7 (p < 0.001).

CONCLUSIONS

Rates of SPB have decreased since the introduction of PCV7, yet SPB still occurs among children in the ED. NVT are increasing in prevalence, and SPB from PCV7-serotypes have decreased.

Investigating the role of pneumococcal neuraminidase A activity in isolates from pneumococcal haemolytic uraemic syndrome

Streptococcus pneumoniae diseases are a rare but increasingly recognized trigger of atypical haemolytic uraemic syndrome (HUS) in young children and associated with a higher mortality rate than diarrhoea-associated HUS. This study aimed to determine the importance of neuraminidase A (NanA) and genomic diversity in the pathogenesis of pneumococcal HUS (pHUS). We investigated the nanA gene sequence, gene expression, neuraminidase activity and comparative genomic hybridization of invasive pneumococcal disease (IPD) isolates from patients with pHUS and control strains matched by serotype and sequence type (ST), isolated from patients with IPD but not pHUS. The nanA sequence of 33 isolates was determined and mutations at 142 aa positions were identified. High levels of diversity were observed within the NanA protein, with mosaic blocks, insertions and repeat regions present. When comparing nanA allelic diversity with ST and disease profile in the isolates tested, nanA alleles clustered mostly by ST. No particular nanA allele was associated with pHUS. There was no significant difference in overall neuraminidase activity between pHUS isolates and controls when induced/uninduced with N-acetylneuraminic acid. Comparative genomic hybridization showed little difference in genetic content between the pHUS isolates and the controls. Results of gene expression studies identified 12 genes differentially regulated in all pHUS isolates compared with the control. Although neuraminidase enzyme activity may be important in pHUS progression and contribute to pathogenesis, the lack of a distinction between pHUS isolates and controls suggests that host factors, such as acquired abnormalities of the alternative complement cascade in young children, may play a more significant role in the outcome of pHUS.

Trends in US hospital stays for Streptococcus pneumoniae-associated hemolytic uremic syndrome

BACKGROUND

Hemolytic uremic syndrome (HUS) is usually associated with diarrheal illness but can also occur in children with Streptococcus pneumoniae infection (SpHUS), particularly those with complicated pneumonia. Based on recent reports that hospital discharges for complicated pneumococcal pneumonia are increasing in US children, we studied whether discharges for SpHUS might also be increasing.

METHODS

We used the Kids' Inpatient Database samples from 1997, 2000, 2003, 2006 and 2009 to estimate trends in US hospital discharges of children (0-18 years) for whom diagnosis codes indicated invasive pneumococcal disease, HUS, or both (SpHUS). Univariate and multivariate analyses were based on 2009 discharges.

RESULTS

During the 5 study years, annual numbers of US hospital discharges for SpHUS approximately doubled (P = 0.025 for linear trend) and cumulatively totaled an estimated 211 discharges. In 2009, SpHUS accounted for 4.6% (95% confidence interval [CI]: 3.0%-6.7%) of HUS discharges, 0.7% (95% CI: 0.5%-1.0%) of invasive pneumococcal disease discharges and 3.0% (95% CI: 2.0%-3.9%) of discharges for complicated pneumococcal pneumonia. Discharges for SpHUS were more likely than those for other invasive pneumococcal disease to occur in children <3 years of age and to incur longer length of stay and greater hospital charges. SpHUS was independently associated with pneumococcal sepsis/bacteremia (age-adjusted odds ratio 3.8; 95% CI: 1.9-7.8) and complicated pneumonia (odds ratio 9.2; 95% CI: 4.1-20.7).

CONCLUSIONS

SpHUS is an uncommon but severe illness that primarily affects young children and is strongly associated with complicated pneumococcal pneumonia. US hospital stays for SpHUS appear to be increasing along with those for complicated pneumococcal pneumonia.

Clinical implications of pneumococcal serotypes: invasive disease potential, clinical presentations, and antibiotic resistance

Streptococcus pneumoniae can asymptomatically colonize the nasopharynx and cause a diverse range of illnesses. This clinical spectrum from colonization to invasive pneumococcal disease (IPD) appears to depend on the pneumococcal capsular serotype rather than the genetic background. According to a literature review, serotypes 1, 4, 5, 7F, 8, 12F, 14, 18C, and 19A are more likely to cause IPD. Although serotypes 1 and 19A are the predominant causes of invasive pneumococcal pneumonia, serotype 14 remains one of the most common etiologic agents of non-bacteremic pneumonia in adults, even after 7-valent pneumococcal conjugate vaccine (PCV7) introduction. Serotypes 1, 3, and 19A pneumococci are likely to cause empyema and hemolytic uremic syndrome. Serotype 1 pneumococcal meningitis is prevalent in the African meningitis belt, with a high fatality rate. In contrast to the capsule type, genotype is more closely associated with antibiotic resistance. CC320/271 strains expressing serotype 19A are multidrug-resistant (MDR) and prevalent worldwide in the era of PCV7. Several clones of MDR serotype 6C pneumococci emerged, and a MDR 6D clone (ST282) has been identified in Korea. Since the pneumococcal epidemiology of capsule types varies geographically and temporally, a nationwide serosurveillance system is vital to establishing appropriate vaccination strategies for each country.

Two cases of hemolytic uremic syndrome caused by Streptococcus pneumoniae serotype 3, one being a vaccine failure

We report two cases of Streptococcus pneumoniae-associated hemolytic uremic syndrome (SP-HUS) caused by serotype 3. One case occurred in an unvaccinated boy and 1 in a girl vaccinated with the 13-valent pneumococcal conjugate vaccine. SP-HUS must be considered in children, and conjugate vaccines may be less effective against serotype 3 than other serotypes.

Evaluation of serotype-specific immunity to Streptococcus pneumoniae in pregnant women and cord blood of infants: impact of race and ethnicity

BACKGROUND

Although invasive pneumococcal disease (IPD) has significantly decreased in children since the introduction of the pneumococcal conjugate vaccine, instances of IPD from non-PCV7 serotypes have increased. Concerns remain regarding the risk for IPD during the neonatal period. Our objective was to measure quantitative antibody levels to 16 serotypes of Streptococcus pneumoniae in pregnant non-Hispanic black, non-Hispanic white, and Hispanic mothers, and in cord blood samples.

METHODS

Antibody levels were evaluated by Luminex assay.

RESULTS

Forty-two percent of all mothers had protective (-0.35 microg/mL) antibody levels to 16 serotypes. Hispanic mothers were most likely to possess protective antibody levels for 12 serotypes but were less likely to possess protective antibody levels for serotypes 9V, 12F, and 18C, compared to non-Hispanic white or black mothers. Thirty-three percent of cord blood samples demonstrated protective antibody levels. Hispanic infants had a higher prevalence of protective antibodies to all serotypes except 11A, 14, 18C, and 23F. Non-Hispanic black infants had a higher prevalence of protective immunity to serotypes 11A, 14, and 18C, and non-Hispanic white infants to only serotype 23F.

CONCLUSIONS

Hispanic mothers and their infants have a higher prevalence of protective immunity to most serotypes of S pneumoniae, compared to white or black mothers/infants. We found no evidence of a lower prevalence of protective immunity to specific serotypes in non-Hispanic black vs. non-Hispanic white infants that might account for the reported higher incidence of IPDs in blacks. Environmental factors in Hispanic mothers may be responsible for their enhanced level of immunity. A significant number of cord blood samples had inadequate levels of protective immunity to a variety of S pneumoniae serotypes.

Streptococcus pneumoniae bacteremia: clinical and microbiological epidemiology in a health area of Southern Spain

Streptococcus pneumoniae remains an important cause of bacteremia worldwide. Last years, a decrease of S. pneumoniae penicillin-resistant isolates has been observed. The objective of this study was to describe the episodes of bacteremia due to S. pneumoniae during a period of 11 years. Epidemiological and clinical data, serotypes causing bacteremia, antibiotic susceptibility and prognosis factors were studied. Over a period of 11 years, all the episodes of S. pneumoniae bacteremia were analysed. Their clinical and microbiological features were recorded. Statistical analysis was carried out to determine risk factors for pneumococcal bacteremia and predictors of fatal outcome. Finally, 67 S. pneumoniae bacteremia episodes were included in this study. The majority of cases were produced in white men in the middle age of their life. The main predisposing factors observed were smoking, antimicrobial and/or corticosteroids administration, chronic pulmonary obstructive disease and HIV infection, and the most common source of bacteremia was the low respiratory tract. The main serotypes found were 19A, 1, 14 and 7F. Seventy-seven percent of these isolates were penicillin-susceptible, and the mortality in this serie was really low. Statistical significance was observed between age, sex and race factors and the presence of bacteremia, and there was relationship between the patient's condition and the outcome. In our study, S. pneumoniae bacteremia is mainly from community-acquired origin mainly caused in men in the median age of the life. 40% of bacteremias were caused by serotypes 19A, 1, 7F and 14. During the period of study the incidence of bacteremia was stable and the mortality rate was very low.

Retrospective review of invasive pediatric pneumococcal diseases in a military hospital in the southern region of Saudi Arabia

BACKGROUND AND OBJECTIVES

Invasive pneumococcal disease (IPD) is associated with high case-fatality rates and serious chronic sequelae. The objective of this study was to assess the magnitude of invasive pneumococcal infections in a pediatric population without universal vaccination during childhood in a single hospital.

DESIGN AND SETTING

Retrospective review of all pediatric cases of invasive pneumococcal infection during a 7-year period.

PATIENTS AND METHODS

We reviewed the microbiological and clinical records of cases of IPD in children <13 years of age admitted to the Armed Forces Hospital, Southern Region, Saudi Arabia.

RESULTS

We identified 41 patients with IPD; 27 (66%) were <2 years of age. Four (50%) of those with pneumoccal meningitis were <2 years of age. The case fatality was 3 of 41 (7.3%) due to meningitis and 2 of 41 (5%) due to sepsis, with a case fatality of 5 (12%) due to meningitis and sepsis. Nine patients developed sequelae; of those with meningitis, 5 (73%) developed sequelae. Only 15 (41%) patients had predisposing medical conditions. The overall intermediate and high levels of pneumococcal resistance to penicillin and ceftriaxone were found to be 48.5%, 2.4% and 2.4%, 0%, respectively. None of the pneumococcal isolates were serotyped, and none of the patients had been vaccinated against pneumococcal infections in our hospital.

CONCLUSIONS

Despite the presence of a targeted immunization program, a considerable number of cases of invasive pneumococcal infections were reported among our pediatric population over a period of 7 years. Prospective studies in serotypes and antibiotic resistance from the southern region are needed to provide baseline information for the formulation and evaluation of a national prevention and control program.

Streptococcus pneumoniae-associated hemolytic uremic syndrome among children in North America

BACKGROUND

To better characterize Streptococcus pneumoniae-associated hemolytic-uremic syndrome (SP-HUS), we report the largest series of SP-HUS among children in North America.

METHODS

We surveyed pediatric members of the Emerging Infections Network to identify SP-HUS cases. Respondents contributed clinical and laboratory features of these pediatric cases.

RESULTS

A total of 37 cases occurring between 1997 and 2009 were submitted. Of them, 33 cases (89%) were culture-confirmed and 4 (11%) were diagnosed clinically. The median patient age was 2 years, and 28 (76%) patients had completed their heptavalent pneumococcal conjugate vaccination (PCV7) series. Most patients presented with pneumonia (84%) and bacteremia (78%), whereas other clinical manifestations such as pericardial effusion (14%) and meningitis (11%) were less common. Of 29 patients, with bacteremia 6 (21%) had S. pneumoniae concurrently isolated from cerebrospinal fluid or pleural fluid. Severe illness was common with 35 (95%) patients requiring admission to the intensive care unit, over half requiring mechanical ventilation and chest tube placement or video-assisted thoracoscopic surgery, and 27 (73%) requiring dialysis during hospitalization. Among 30 patients with follow-up of 6 months, 7 (23%) remained dialysis dependent, 3 (10%) had undergone renal transplantation, 4 (13%) had neurologic sequelae, and 1 (3%) died. Among 24 serotyped isolates, 96% were non-PCV7 serotypes, most commonly 19A (50%), 92% are included in PCV13, and 10% were penicillin nonsusceptible (minimal inhibitory concentration >2 μg/mL).

CONCLUSIONS

North American children with SP-HUS had severe clinical manifestations and significant morbidity. In this series, nearly all cases were caused by serotypes that are not in PCV7 but are included in PCV13.

Reduced susceptibility to penicillin among pneumococci causing invasive infection in children - Canada, 1991 to 1998

OBJECTIVE

To determine, over time, the rate and serotypes of pneumococci with reduced penicillin susceptibility obtained from children with invasive infection.

DESIGN

Active, hospital-based, multicentre surveillance spanning from 1991 to 1998.

SETTING

Eleven Canadian tertiary care paediatric facilities located from coast to coast.

POPULATION STUDIED

1847 children with invasive pneumococcal infection whose isolates (from a normally sterile site) were available for serotyping and standardized testing for penicillin susceptibility at the National Centre for Streptococcus.

MAIN RESULTS

The prevalence of reduced penicillin susceptibility increased from 2.5% of 197 cases in 1991 to 13.0% of 276 cases in 1998. In the latter year, 8.7% of isolates had intermediate level resistance, and 4.3% had high level resistance. Since they were first detected in 1992, strains with high level resistance have been encountered only sporadically at most centres, but by 1998, all centres but two had encountered examples. Of 40 isolates with high level resistance and 101 isolates with intermediate level resistance, serotypes matched those included in new seven-valent conjugate vaccines for children in 97.5% and 79.2% of cases, respectively.

CONCLUSIONS

Pneumococci with reduced susceptibility to penicillin are increasing in frequency across Canada among children with invasive infection. The Immunization Monitoring Program, Active data indicate that new conjugate vaccines could help to curb infections due to pneumococci with reduced susceptibility to penicillin but are unlikely to control completely the problem of antibiotic resistance.

Serotype 19A Is the most common serotype causing invasive pneumococcal infections in children

OBJECTIVE

The purpose of this study was to monitor the clinical and microbiologic features of invasive infections caused by Streptococcus pneumoniae among children before and after the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7).

DESIGN

We conducted a 15-year prospective surveillance study of all invasive pneumococcal infections in children. The sample included infants and children at 8 children's hospitals in the United States with culture-proven invasive S pneumoniae infections.

RESULTS

Since the implementation of routine PCV7 immunization in 2000, invasive infections have decreased yearly from 2001 through 2004, to a nadir of 151 infections; the rate then increased from 2005 through 2008. Compared with the pre-PCV7 era, a greater proportion of children with invasive pneumococcal infection had an underlying condition in the post-PCV7 period. Compared with the total number of annual admissions, the number of 19A isolates increased significantly from 2001 to 2008 (P < .00001). In 2007 and 2008, only 16 isolates (4%) were vaccine serotypes; 19A accounted for 46% (168 of 369) of the non-PCV7 serotypes. Thirty percent of the 19A isolates were multidrug resistant. Serotypes 1, 3, and 7F accounted for 22% of the non-PCV7 serotypes. Among children with invasive pneumococcal infections, the likelihood of a 19A serotype increased with the number of preceding PCV7 doses.

CONCLUSIONS

Since 2005, the number of invasive pneumococcal infections in children has increased at 8 children's hospitals, primarily as a result of serotype 19A isolates, one third of which were resistant to multiple antibiotics in 2007 and 2008. Continued surveillance is necessary to detect emerging serotypes after the planned introduction of 13-valent or other pneumococcal vaccines.

Streptococcus pneumoniae--associated hemolytic uremic syndrome: classification and the emergence of serotype 19A

Streptococcus pneumoniae-associated hemolytic uremic syndrome (HUS) is an underrecognized condition that mainly occurs in young children. Early diagnosis is important because of the potential to improve morbidity and mortality rates. The purposes of this report are to review the clinical and laboratory features of 14 patients with pneumococcal HUS and present a modified classification to capture cases that may not have been documented with a diagnosis of pneumococcal HUS. We thereby provide a rationale for including patients with concurrent disseminated intravascular coagulopathy and/or those whose culture results were negative, and we highlight the emergence of serotype 19A subsequent to the introduction of 7-valent pneumococcal protein conjugate vaccine (Prevnar). This is the largest series of such subjects (to our knowledge) from a single center. Sixty-four percent of the patients recovered without any long-term sequelae. Three patients developed chronic kidney disease, 1 developed end-stage renal failure, and 1 died in the acute phase. The greatest risk factor for the development of chronic kidney disease is the need for acute dialysis for >20 days, and death in the acute phase is rare unless meningitis is the primary infection.

Ten years of pneumococcal-associated haemolytic uraemic syndrome in New Zealand children

AIM

To describe the epidemiology, clinical features, management and outcome of pneumococcal-associated haemolytic-uraemic syndrome (P-HUS) in New Zealand over the past decade.

METHODS

A retrospective chart review of children with P-HUS from 1998 to 2007 that were prospectively reported to the New Zealand Paediatric Surveillance Unit. P-HUS was defined as microangiopathic haemolytic anaemia (Hb <100 g/L with fragmented red blood cells), thrombocytopaenia (platelet count <130 x 10(9)/L), acute renal impairment with oliguria and elevated plasma creatinine, and confirmed or suspected pneumococcal infection.

RESULTS

Eleven children (nine male, two female), predominately Maori and Polynesian (10 children) were studied. The median age was 8.5 months. The median duration of hospitalisation was 25 days. Of the infections, 10 were confirmed pneumococcal (six pneumonia, four meningitis) and one pneumonia was suspected pneumococcal (culture negative, however T activation positive). Nine patients required dialysis for a median duration of 13 days. One child with meningitis died after therapy was withdrawn because of severe neurological injury. One patient developed end stage kidney disease and two further children had evidence of persisting renal sequelae at follow-up.

CONCLUSIONS

Pneumococcal disease remains an important public health problem in New Zealand children, particularly those of Maori and Pacific Island ethnicity. P-HUS should be considered in pneumococcal disease associated with severe haematological and renal abnormalities. These children should be monitored long-term, as they are at risk of permanent renal injury.

Host and microbiologic factors associated with mortality in Taiwanese children with invasive pneumococcal diseases, 2001 to 2006

We concurrently evaluated host- and organism-related factors in determining the outcomes of 160 invasive pneumococcal diseases episodes in 158 Taiwanese children during 2001 and 2006. Most (138/160, 86.2%) episodes occurred at age less than 60 months, and an underlying condition was present in 35 (22.2%) cases. Common disease syndromes included complicated pneumonia (29.4%), uncomplicated pneumonia (29.4%), occult bacteremia (17.5%), and meningitis (14.4%). Mortality (13/160, 8.1%) was associated with age less than 24 months, underlying conditions, meningitis, cytopenia, intensive care, and penicillin MIC >or=2 microg/mL in univariate analysis. Pneumococcal serotypes, genotypes, origin of infections, and discordant therapy did not influence the outcome. Multivariate analysis determined the presence of underlying conditions (adjusted odds ratio [OR], 30.5; 95% confidence interval [CI], 4.8-193.1) and penicillin MIC >or=2 microg/mL (adjusted OR, 8.1; 95% CI, 1.4-47.3), which are the independent predictors for fatality. This finding highlighted the importance of immunization of disadvantaged children, targeting drug-resistant pneumococci.

Pneumococcal osteomyelitis: report of one case

Acute osteomyelitis is uncommon in pediatric patients, affecting one in five thousand children younger than the age of thirteen. Bone infection caused by Streptococcus pneumoniae is extremely rare, accounting for only 1.3% of acute osteomyelitis in children. We report a case of penicillin-resistant Streptococcus pneumoniae-induced acute osteomyelitis in a 7-month-old male infant who was treated successfully with intravenous vancomycin and oral clindamycin.

Streptococcus pneumoniae-associated hemolytic uremic syndrome

Streptococcus pneumonia-associated hemolytic uremic syndrome (HUS) (pneumococcal HUS) is an uncommon condition mainly observed in young children. Early recognition is critical, because of the potential to improve morbidity and mortality. In our review we summarize the pathophysiology, clinical features, diagnostic difficulties and management of this potentially under-diagnosed condition.

Serotype distribution and antimicrobial resistance patterns of Streptococcus pneumoniae isolated from children in China younger than 5 years

This study examined the epidemiology, antibiotic susceptibility, and serotype distribution of Streptococcus pneumoniae associated with invasive and noninvasive pneumococcal disease in children in China. A total of 451 clinical isolates from children (age, <5 years) were collected from 8 cities from January 2005 to December 2006, including 31 isolated from invasive disease. In vitro susceptibility to 14 antimicrobial agents was determined by the agar dilution method. Among all isolates tested, 64.3% were resistant to penicillin, and for invasive isolates, the resistance rate was 55.2%. Isolates from Wuhan and Nanjing showed the highest prevalence of penicillin resistance (89.6% and 85%), followed by those from Shenzhen (72.4%) and Chengdu (56.7%). Multidrug resistance rates to tetracycline, erythromycin, and clindamycin reached 90%. The 6 most common serotypes were 19F, 19A, 14, 6B, 23F, and 15. These accounted for 80.7% of the isolates. Resistance to penicillin varied among the 6 leading serotypes, ranging from 20% in serotype 15 to 87.3% in serotype 19F. Each of the 8 cities had different serotype distribution. The potential coverage by 7-, 10-, and 13-valent pneumococcal conjugate vaccine were 63.6%, 64.8%, and 79.6%, respectively.

Streptococcus pneumoniae bacteraemia in children

Occult bacteraemia is the most frequent invasive disease caused by Streptococcus pneumoniae in children less than 3 years of age. Despite the relative frequency of this infection, its management is still a challenging task for paediatricians because fever is often the only symptom and a considerable overlap exists in the clinical presentation of children with fever without a focus due to viral illness and children with occult bacteraemia. Management protocols take into account the age of the patient, the clinical score for severity and the results of laboratory tests such as the white blood cell count, the C-reactive protein and the blood procalcitonin level in order to define accurately who will benefit from an antibiotic treatment. Despite appropriate healthcare facilities and access to care the case fatality rate in developed countries is around 9% in children aged less than 1 year. Prevention with the 7-valent conjugate vaccine against S. pneumoniae will decrease morbidity and mortality associated with invasive disease due to these bacteria. However, replacement by non-vaccine serotypes has been noted in countries where the vaccine is widely used and this concern needs to be monitored carefully over the next few years.

Recurrent systemic pneumococcal disease in children

BACKGROUND

Recurrent systemic pneumococcal infection usually occurs in immunocompromised patients and patients with underlying conditions.

METHODS

Between 1993 and 2006, investigators at 8 pediatric hospitals prospectively identified cases of invasive pneumococcal disease (IPD) and retrospectively documented demographics and clinical information. Antibiotic susceptibility was determined for penicillin and ceftriaxone by microbroth dilution. Isolates were serotyped and molecular relatedness determined using pulse field gel electrophoresis (PFGE).

RESULTS

Four thousand sixty-seven children were diagnosed with IPD over 12.3 years. One hundred and 8 episodes of recurrent disease were seen in 90 children (2.6%); 75 experienced 2 infections, 12 experienced 3 infections and 3 experienced 4 infections. Fourteen of the 15 children with >2 episodes of infection had underlying conditions. The mean duration between 1st and 2nd infection was 22.9 weeks for children with no known underlying condition and 43.0 weeks for children with an underlying condition (P = 0.001). Seventy episodes of IPD among the 90 patients were caused by a different serotype or a different genotype as demonstrated by the PFGE. Sixteen children had intervals <30 days between infections; 7 were caused by different strains.

CONCLUSIONS

Approximately 80% of the children with recurrent invasive pneumococcal disease had underlying conditions. Seven of 16 children with recurrent infection <30 days apart were caused by acquisition of a new strain. Relapse of infection requires documentation that the pneumococcal isolates are not only the same serotype but also have the same PFGE patterns.

Ten-year surveillance of pneumococcal infections in Temuco, Chile: implications for vaccination strategies

We monitored Streptococcus pneumoniae serotypes causing invasive infections in patients admitted to one hospital in southern Chile during a 10-year period (1994 to 2004). All specimens isolated from patients with invasive S. pneumoniae infections were serotyped at the CDC in Atlanta, GA. A total of 508 isolates belonged to 58 serotypes. There were 95 infections in patients <2 years old, 33 infections in patients 2 to 4 years old, 61 infections in patients 5 to 14 years old, 66 infections in patients 15 to 44 years old, 134 infections in patients 45 to 64 years old, and 120 infections in patients >or=65 years old. The 10 serotypes isolated with the highest frequency in all groups were, in decreasing order, 1, 3, 14, 5, 19F, 6B, 7F, 12F, 23F, and 6A. The 10 most frequent isolates in children under 2 years of age were 1, 6B, 14, 19F, 5, 23F, 6A, 9V, and 7F. In patients >or=65 years old, the most common serotypes were 3, 7F, 1, 14, 19A, 23F, 19F, 35B, 4, and 5. Penicillin resistance was detected in 14 (2.7%) clinical specimens isolated since 1998, with 13 resistant strains identified since 2001. Vaccine coverage for the 7-valent conjugate vaccine was 42% for children <2 years of age. This study is important for the design of vaccines for this region and to evaluate public health measures to decrease pneumococcal infections.

Streptococcus pneumoniae skin and soft tissue infections: characterization of causative strains and clinical illness

Streptococcus pneumoniae is an uncommon cause of skin and soft tissue infections, yet the incidence and clinical significance of its isolation in samples of skin or soft tissues in unselected hospital samples is poorly understood. In the present study, a review was conducted of the records of all patients with skin and soft tissue infections due to S. pneumoniae at a university hospital between January 1994 and December 2005. The isolates were identified by standard methods and were serotyped, and susceptibility testing was performed by the broth microdilution method following the guidelines of the Clinical and Laboratory Standards Institute. During the study period, 3,201 isolates of S. pneumoniae were recovered from several sources. Of these, 69 (2.2%) were from skin and soft tissue samples (69 patients). Complete information could not be obtained for 13 patients. Of the 56 patients remaining, 36 (64.3%) were infected and fulfilled the inclusion criteria. The following types of infections were observed: surgical wound infection (n = 11), burn infection (n = 7), pyomyositis (n = 6), cellulitis (n = 4), perineal or scrotal abscess (n = 3), and other (n = 5). Thirty-one (86%) patients had a favorable outcome, and 5 (13.8%) patients died. Mortality was directly attributable to S. pneumoniae infection in three of the five fatal cases. Of the 39 S. pneumoniae isolates obtained (36 from skin and soft tissues, three from blood cultures), 58.9% were penicillin nonsusceptible, 7.7% were cefotaxime nonsusceptible, and 20.5% were erythromycin resistant. The most frequent serotypes were 3, 19, 11, and 23. Of the overall number of isolates of S. pneumoniae recovered in a general institution, 2.2% involved skin and soft tissues (of which 64% were clinically significant). Mortality due to pneumococcal skin and soft tissue infections was low.

A Comparison of group A Streptococcus versus Streptococcus pneumoniae pneumonia

BACKGROUND

St reptococcus pyogenes is an uncommon cause of community-acquired pneumonia in children. Further, its clinical course in comparison to pneumonia caused by Streptococcus pneumonia has not been previously highlighted.

METHODS

We reviewed medical records of children 0-18 years of age from April 1983 to April 2005, with discharge diagnoses of invasive disease caused by group A streptococcus (GAS) (Streptococcus pyogenes), or Streptococcus pneumonia (SP) or pneumonia. Data were extracted from the charts, and a comparison of clinical characteristics between the 2 etiologies was performed. Confirmed disease required blood or pleural fluid isolates. Patients with single isolates of GAS in tracheobronchial secretions or sputum were classified as having presumed disease caused by GAS. Patients with confirmed disease due to GAS and SP were compared with respect to clinical characteristics.

RESULTS

Of 103 patients with invasive GAS disease, 12 (11.6%) had confirmed GAS lobar pneumonia. In addition 7 patients had presumed GAS pneumonia. There were 54 patients with confirmed SP pneumonia. Most children who had GAS pneumonia were healthy and recovered completely. Compared with patients with confirmed SP pneumonia, those with confirmed GAS pneumonia had more frequent and larger effusions, more culture positive effusions, had prolonged fever, and had longer hospitalizations. There was not an increasing trend to GAS pneumonia over the 22-year period. There was not a predominant serotype responsible for the pneumonias.

CONCLUSIONS

Lobar GAS pneumonia represents approximately 11% of all cases of invasive disease in this institution during a 22-year period. Compared with patients with SP pneumonia, it appears to cause more effusions and morbidity. The organism is also more frequently recovered from pleural fluid.

Is Antibiotic Cycling the Answer to Preventing the Emergence of Bacterial Resistance in the Intensive Care Unit?

Antibiotic resistance has emerged as an important determinant of mortality for patients in the intensive care unit (ICU) setting. This is largely due to the increasing presence of pathogenic microorganisms with resistance to existing antibiotic agents, resulting in the administration of inappropriate treatment. Escalating antibiotic resistance has also been associated with greater overall health care costs, as a result of prolonged hospitalizations and convalescence associated with failure of antibiotic treatment, the need to develop new antibiotic agents, and the implementation of broader infection control and public health interventions aimed at curbing the spread of antibiotic-resistant pathogens. Antibiotic cycling has been advocated as a tool to reduce the occurrence of antibiotic resistance, especially in the ICU setting. Unfortunately, the cumulative evidence to date suggests that antibiotic cycling has limited efficacy for preventing antibiotic resistance. Nevertheless, a strategy whereby multiple or all classes of antibiotics are available for use (i.e., antibiotic heterogeneity) can be part of a broader effort aimed at curtailing antibiotic resistance within ICUs. Such efforts should be routine, given the limited availability of new antibiotic drug classes for the foreseeable future.

Safety and immunogenicity of heptavalent pneumococcal conjugate vaccine booster in taiwanese toddlers

BACKGROUND/PURPOSE

Pneumococcal infection causes high morbidity and mortality in children. Prevention of pneumococcal diseases by effective vaccination is an urgent need. This study evaluated the safety and immunogenicity of heptavalent pneumococcal conjugate (7VPnC) vaccine (serotypes 4, 6B, 9V, 14, 18C, 19F, 23F) booster dose administered at 15-20 months of age in Taiwanese toddlers.

METHODS

Fifty-eight healthy Taiwanese toddlers who were primed with three doses of the 7VPnC vaccine in infancy received a booster dose in an open-label, noncomparative trial. Routine oral polio vaccine and diphtheria toxoid, tetanus toxoid, and pertussis vaccine were administered concomitantly. Surveillance for safety was conducted after vaccination. Antibody concentration to each of the seven pneumococcal serotypes was measured before and 1 month after the booster dose.

RESULTS

Mild to moderate local reactions were common (45-50%). Fever, fussiness, restlessness, and loss of appetite were the most frequent systemic reactions (31-50%). Before the booster dose of vaccine, 68% (for serotype 18C) to 100% (for serotype 14) of subjects had antibody concentrations >or= 0.2 microg/mL to different pneumococcal serotypes. After the booster dose, the geometric mean concentration of IgG increased significantly (p < 0.001) for all seven serotypes indicating the induction of immunologic memories. Ninety-eight percent of the toddlers had antibody concentration >or= 0.2 microg/mL against all serotypes after the booster.

CONCLUSION

The 7VPnC vaccine containing the prevalent serotypes in Taiwan is safe and effective in boosting immunity against pneumococcal disease in Taiwanese children.

Active surveillance of Streptococcus pneumoniae bacteremia in Italian children

There are few data published regarding the incidence of Streptococcus pneumoniae bacteremia in Italian children. A 14-month surveillance study was conducted in 10 paediatric hospitals to investigate the rate of Sp bacteremia in children aged less than 5 years. The serotype prevalence and antimicrobial susceptibility of isolates were determined. A total of 55 Sp isolates were obtained from 4576 blood cultures (incidence rate, 1.2%). In order of frequency, the most common serotypes were 14, 23F, 19F, 9V, 1. Serotypes in the 7-valent conjugate pneumococcal vaccine (4, 6B, 9V, 14, 18C, 19F, 23F) accounted for 70% of isolates under 2 years of age, and 58% in the interval between 2 and 5 years of age.

Hemolytic uremic syndrome associated with pneumococcal pneumonia in Taiwan

Streptococcus pneumoniae ( S. pneumoniae ) has been associated with hemolytic uremic syndrome (HUS), which is an unusual but serious disease in childhood. We conducted a retrospective review of children aged less than 18 years with S. pneumoniae -associated HUS in northern Taiwan from January 2000 to June 2005. The demographic characters, clinical courses, and outcomes were analyzed. Seven children (three girls, four boys) with S. pneumoniae -associated HUS were studied. The median age at onset of HUS was 40 months (range: 25-60 months). The median duration of hospital stay was 36 days (range: 15-50 days). The interval between the onset of illness attributable to S. pneumoniae and the development of HUS was around 1-2 weeks. The onset of oliguria developed within 2 weeks after illness. Six patients required dialysis with median duration of 16 days. Three patients had leukopenia as the initial presentation. All seven patients had pneumococcal pneumonia complicating with empyema, and two of them received decortication via video-assisted thoracoscopic surgery. Between patients who needed dialysis or not, there was no significant difference in age, sex, duration of thrombocytopenia, incidence of extra-renal complications, such as hepatitis, pancreatitis, and hypertension, and length of hospital stay. The seven patients survived with normal renal function. HUS is a potentially fatal complication of S. pneumoniae infection. Clinicians managing patients with pneumococcal pneumonia with empyema accompanied by leukopenia should beware of the development of HUS. The long-term prognosis for recovery of renal function appears to be good in these patients in northern Taiwan.

Streptococcus pneumoniae serogroups 15 and 33: an increasing cause of pneumococcal infections in children in the United States after the introduction of the pneumococcal 7-valent conjugate vaccine

BACKGROUND

After the widespread use of the 7-valent pneumococcal conjugate vaccine, replacement serotypes have emerged. Serogroups 15 and 33 have emerged as nonvaccine serotypes causing invasive disease. We describe the clinical characteristics of children with infections caused by these serogroups and determined the genetic relationship of the strains.

MATERIALS AND METHODS

The United States Pediatric Multicenter Pneumococcal Surveillance Group has prospectively identified children with pneumococcal infections since 1993. Charts were reviewed retrospectively, isolates were serogrouped and serotyped and randomly selected strains were fingerprinted with the use of pulsed field gel electrophoresis. Selected strains were further characterized by multilocus sequence typing.

RESULTS

Between January 1994 and December 2004, 103 children had pneumococcal disease caused by serogroup 15, and 40 children had infections caused by serogroup 33. There was an increase from a mean of 7 cases per year for serogroup 15 in the prevaccine period to 14 cases per year in the postvaccine period and from 2 cases per year for serogroup 33 to 7 cases per year in the same periods. Isolates were susceptible to penicillin and ceftriaxone in both periods. A predominant clone was found in each serogroup representing 60% (30 of 50) of serogroup 15 strains and 83% (24 of 29) of the serotype 33F strains. The serogroup 15 clone comprised strains of serotypes 15B and 15C, whereas the 33 clone contained only serotype 33F strains. One isolate from each of the 15 and 33 clones was characterized by multilocus sequence typing and were found to be ST199 and 100, respectively.

CONCLUSIONS

Pneumococcal disease in children caused by penicillin-susceptible clones of serogroups 15 and 33 is increasing in the United States. Clinicians should consider replacement serotypes when encountered with invasive pneumococcal disease in vaccinated children.

Risk factors for mortality in Paraguayan children with pneumococcal bacterial meningitis

BACKGROUND

Over the last decade Streptococcus pneumoniae has emerged as the most common bacterial pathogen for meningitis in all age groups, beyond the neonatal period.

OBJECTIVE

To determine the epidemiological and clinical characteristics; and risk factors for mortality of pneumoccocal meningitis in children in a developing transitional country.

MATERIALS AND METHODS

A retrospective study that included patients<15 years of age admitted at the Instituto de Medicina Tropical of Paraguay, from January 1990 until December 2003 with the diagnosis of bacterial meningitis caused by S. pneumoniae. Clinical and laboratory data were collected and analysed in order to identify risk factors associated with morbidity and mortality outcomes of this infection.

RESULTS

Seventy-two patients (between the ages of 35 days and 14 years) were identified. Forty-two per cent of patients had seizures prior to or at the time of admission, 36% were admitted in a comatose state, and 19% with shock. Mortality was 33% (24/72), and 18% of the survivors (11/60) developed severe sequelae. Upon admission, the following variables were strongly correlated with mortality: age<12 months (P=0.007), the presence of seizures (P=0.0001) or development of seizures 48 h after admission (P=0.01), a cerebrospinal fluid (CSF) glucose level of <10 mg/dl (P=0.01), CSF albumin>200 mg/dl (P=0.0003), an absolute blood neutrophil count<2000/mm3 (P=0.006) and a haemoglobin value of <9 g/dl (P=0.0001).

CONCLUSIONS

This study confirms the high morbidity and mortality associated with S. pneumoniae meningitis in Paraguay. Certain clinical parameters and laboratory findings in blood and CSF at the time of admission could be used as predictors for mortality or severe sequelae among survivors.

Strategies to prevent antimicrobial resistance in the intensive care unit

OBJECTIVE

To assemble the available clinical data for the prevention of antimicrobial resistance into practical recommendations for clinicians.

DATA SOURCE

A Medline database and references from identified articles were employed to perform a literature search relating to the prevention of antimicrobial resistance.

CONCLUSIONS

Antimicrobial resistance has emerged as an important determinant of mortality for patients in the intensive care unit. This is largely due to the increasing presence of pathogenic microorganisms with resistance to existing antimicrobial agents, resulting in the administration of inappropriate treatment. Effective strategies for the prevention of antimicrobial resistance within intensive care units are available and should be aggressively implemented. These strategies can be divided into nonpharmacologic infection control strategies (e.g., routine hand hygiene, implementation of infection-specific prevention protocols) and antibiotic management strategies (e.g., shorter courses of appropriate antibiotic treatment, narrowing of antimicrobial spectrum based on culture results). Increasing current efforts aimed at the prevention of antimicrobial resistance is especially important given the limited availability of new antimicrobial drug classes for the foreseeable future.

Antibiotic resistant Streptococcus pneumoniae and hemolytic uremic syndrome

The hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in young children and most often follows an episode of gastroenteritis caused by an enterohemorrhagic strain of Escherichia coli (O157:H7). HUS induced by Streptococcus pneumoniae (SP) is rare. We report an 18-month-old patient who presented with HUS associated with SP resistant to penicillin and cephalosporins.

CONCLUSION

Despite a protracted course including renal failure requiring 15 days of peritoneal dialysis, her kidney function completely recovered.

Decreasing antibiotic overuse in neonatal intensive care units: quality improvement research

Overutilization of antibiotics and emergence of resistant bacteria are important problems, particularly in intensive care units. To date, reproducible interventions to improve antibiotic utilization in hospitals have not been proven to be effective or safe. Evidence-based medicine, clinical practice guidelines, and health information technology are frequently promoted as means to cross the "quality chasm" described by the Institute of Medicine. This article outlines how these approaches intersect in a strategy for quality improvement research evaluating the safety and effectiveness of clinical practice guidelines designed to improve antibiotic use in neonatal intensive care units.