Post-pneumococcal Conjugate Vaccine Era Research Articles

Prevalence and resistance characteristics of multidrug-resistant Streptococcus pneumoniae isolated from the respiratory tracts of hospitalized children in Shenzhen, China.

PCV13 introduction in China has led to a significant reduction of vaccine serotype Streptococcus pneumoniae. However, non-vaccine serotypes with highly resistance and invasiveness were often reported in the post-pneumococcal conjugate vaccine era and there was regional differences. A total of 669 S. pneumoniae strains were collected from the respiratory tracts of hospitalized children at Shenzhen Children's Hospital in 2021 and 2022. Antimicrobial resistance (AMR) characteristics were assessed through antibiotic susceptibility testing performed with the VITEK 2 compact system. AMR genes and single nucleotide polymorphisms (SNPs) in pbp1a, pbp2b, and pbp2x were identified via analysis of whole genome sequencing data. Statistical examination of the data was conducted employing chi-square and Fisher's exact tests. We found that non-vaccine serotypes strains had accounted for 46.6% of all the pneumococcal isolated strains. The most common non-vaccine serotype is 23A, with a prevalence rate of 8.9%, followed by 15A (6.6%), 6E (5.7%), 34 (3.2%), and 15B (2.9%). The multidrug resistance rates (MDR) of vaccine serotypes were 19F (99.36%), 19A (100%), 23F (98.08%), 6B (100%), and 6C (100%). Meanwhile, the MDR of non-vaccine serotypes were 15B (100.00%), 6E (100%), 15C (100%), 34 (95.24%), and 23A (98.31%). Resistance rates of 6E to more than six antibiotic classes reached 89.47%, which is similar to 19F (83.33%) and 19A (90%). Unique resistance profiles were also identified for non-vaccine serotypes, including significantly higher resistance to chloramphenicol in 6E, 15B, and 15C than in 19F and 19A. Furthermore, through genome sequencing, we revealed strong correlation of cat-TC with chloramphenicol resistance, patA/patB with tetracycline resistance, ermB and pmrA with erythromycin resistance. The introduction of PCV13 into China from 2017 has led to a shift in the dominant composition of pneumococcal strains. There has been a notable rise and spread of multidrug-resistant non-vaccine serotypes among children. Specifically, the non-vaccine serotype 6E, which was not widely reported in China previously, has emerged. To comprehend the resistance mechanisms, it is crucial to further investigate the molecular and genetic characteristics of these non-vaccine serotypes.

Epidemiology of bacteremia in a pediatric population – A 10-year study

IntroductionWith the widespread introduction of conjugate meningococcal and pneumococcal vaccines, the prevalence and etiology of invasive bacterial infections have changed. We aimed to review all cases of bacteremia in a level II pediatric department over a ten-year period in the post-pneumococcal conjugate vaccine era. MethodsWe reviewed all positive blood cultures (BC) obtained in our department between 2007 and 2016. Results were classified as contaminants, potential pathogens or confirmed pathogens, based on species, number of positive BC in the episode and the patients’ medical history. Demographic and clinical data were collected for patients with identified pathogens. ResultsA total of 638 positive BC were identified (6.6% of total BC); 120 (1.2%) were considered to represent true bacteremia. The most frequently identified microorganism was Streptococcus pneumoniae (29.2%), with a decrease in the number of cases between 2008 and 2015. Staphylococcus aureus was the second most common organism (19.2%) being 21.7% of these methicillin-resistant. Escherichia coli was the most common isolate in children aged less than three months. ConclusionWe found a rate of true bacteremia in children similar to recent studies. Although Streptococcus pneumoniae remains the most common microorganism, its prevalence may be declining. Monitoring microbiological data in children has implications in practice, particularly in local antibiotic prescription.

Genetic characterization of penicillin-binding proteins of nonencapsulated Streptococcus pneumoniae in the postpneumococcal conjugate vaccine era in Japan

ObjectivesNonencapsulated Streptococcus pneumoniae (NESp) is emerging after the introduction of pneumococcal conjugate vaccines (PCVs). This study aimed to elucidate the genetic characteristics of penicillin-binding proteins (PBPs; PBP1a, 2b, and 2x) associated with penicillin nonsusceptibility in emergent NESp. MethodsA total of 71 NESp isolates that were identified in our previous study during the PCV era in Japan (2011–2019) were analyzed for their amino acid sequences of transpeptidase domain in PBP 1a, 2b, and 2x. ResultsOverall, we identified 21 different PBP profiles (1a-2b-2x), all of which represent novel PBP profiles. The dominant PBP profiles were 13-16-ne1 (32.4%, n = 23), ne1-16-ne2 (14.1%, n = 10), and 13-7-ne4 (7.0%, n = 5) (novel PBP type was numbered with “ne” denoting “nonencapsulated”), accounting for 53.5% of all isolates. All isolates with the PBP profiles 13-16-ne1 and 13-7-ne4 and those having PBP1a type-13 and -131, PBP2b type-7, -ne1, and -ne2 showed nonsusceptibility to penicillin. A high degree of genetic diversity was found in PBP2x, with most of them (81.7%) being new types. ConclusionsOur current study identified the 21 novel PBP profiles and remarkable mutations in the PBPs, which may be potentially associated with penicillin nonsusceptibility in NESp.

Clinical pneumonia in the hospitalised child in Malawi in the post-pneumococcal conjugate vaccine era: a prospective hospital-based observational study

ObjectiveAssess characteristics of clinical pneumonia after introduction of pneumococcal conjugate vaccine (PCV), by HIV exposure status, in children hospitalised in a governmental hospital in Malawi.Methods and findingsWe evaluated 1139 children...

Aetiology and presentation of childhood pleural infections in the post-pneumococcal conjugate vaccine era in South Africa.

Background Complications of respiratory infections including pleural effusion (PE) are associated with a high morbidity. Differentiating between PE caused by Mycobacterium tuberculosis (Mtb) infection and other bacterial infections in endemic areas is difficult in children, thus, impacting treatment. Objectives To investigate the aetiology of PE and features distinguishing tuberculosis (TB) from bacterial PE in children. Methods We conducted a prospective study in children with PE admitted to a tertiary hospital in Cape Town from December 2017 to December 2019. Clinical information and routine laboratory investigations were compared between children with bacterial, Mtb or unclassified PE, categorised according to study definitions. Results A total of 91 patients were included in the present study and their median age was 31 months (interquartile range (IQR) 11.8 - 102.1). The aetiology was bacterial in 40% (n=37), Mtb in 39% (n=36) and unclassified in 20% (n=18) of patients. Staphylococcus aureus was the most common bacterial isolate, confirmed in 65% (n=24/37) patients, and Streptococcus pneumoniae was confirmed in only 8% of patients. TB was microbiologically confirmed in 33% (n=12/36) of patients. Patients with TB were older (91.6 v. 11.8 months; p<0.001), with more weight loss (28 v. 12 patients; p<0.001), and longer cough duration (10 v. 4 days; p<0.001) than those with other bacterial PE. In contrast, the latter had significantly higher serum C-reactive protein (median 250 v. 122 mg/L; p<0.001), procalcitonin (11 v. 0.5 mg/L; p<0.001), pleural fluid lactate dehydrogenase (7 280 v. 544 U/L; p<0.001), and adenosine deaminase levels (162 v. 48 U/L; p<0.001) and lower glucose levels (1.3 v. 4 mmol/L; p<0.001). Conclusion Post 13-valent pneumococcal conjugate vaccine, S. aureus is the dominant cause of PE in children using traditional culture methods, while Mtb remains a common cause of PE in our setting. Useful clinical and laboratory differences between Mtb and other bacterial PE were identified, but the cause of PE in 20% of children was underdetermined. Molecular testing of pleural fluid for respiratory pathogens may be useful in such children.

Occult bacteremia in children with simple febrile seizure in the post-pneumococcal conjugate vaccine era

Purpose: The authors aimed to investigate the utility of blood culture (BC) for children with simple febrile seizure (SFS) in the emergency department (ED) in the post-10/13-valent pneumococcal conjugate vaccine (PCV) era. Methods: This study was performed at the ED of a tertiary care university-affiliated women and children’s hospital, and involved 3,237 previously healthy children aged 6-60 months who visited the ED with SFS from January 2013 through December 2017. The SFS was defined according to the International Classification of Diseases, 11th Revision codes related to seizure. The children were divided into 2 groups according to the vaccination rates of the period of their visit: the 70-PCV (70%, 2013-2014) and 97-PCV (97%, 2015-2017) groups. The primary outcome was the yield, defined as a true positivity of BC. In addition, we collected information on baseline characteristics, ED length of stay, inflammatory biomarkers, and ED outcomes. Results: Of the 1,578 children with SFS who underwent BC, 1,357 belonged to the 97-PCV group. The median age of the study population was 22 months (interquartile range, 16.0-30.0), and 935 children (59.3%) were boys. Of the 41 children (2.6%) with positive BC results, 3 had the yield (0.2%): Staphylococcus aureus in 2 children and Streptococcus pneumoniae in the other. All 3 children belonged to the 97-PCV group. There were 38 contaminated BCs (2.4%; 95% confidence interval, 1.6%-3.2%). The 97-PCV group showed a shorter median ED length of stay (166.0 minutes [108.0-279.5] vs. 143.0 [109.5-209.5]; P = 0.010) and a lower rate of hospitalization (39.4% vs. 12.8%; P &lt; 0.001). No differences between the 2 groups were found in the baseline characteristics and biomarkers.Conclusion: This study suggests a low utility of BC in previously healthy children with SFS in emergency settings in the post-10/13-valent PCV era.

Epidemiology of bacteremia in a pediatric population – A 10-year study

IntroductionWith the widespread introduction of conjugate meningococcal and pneumococcal vaccines, the prevalence and etiology of invasive bacterial infections have changed. We aimed to review all cases of bacteremia in a level II pediatric department over a ten-year period in the post-pneumococcal conjugate vaccine era. MethodsWe reviewed all positive blood cultures (BC) obtained in our department between 2007 and 2016. Results were classified as contaminants, potential pathogens or confirmed pathogens, based on species, number of positive BC in the episode and the patients’ medical history. Demographic and clinical data were collected for patients with identified pathogens. ResultsA total of 638 positive BC were identified (6.6% of total BC); 120 (1.2%) were considered to represent true bacteremia. The most frequently identified microorganism was Streptococcus pneumoniae (29.2%), with a decrease in the number of cases between 2008 and 2015. Staphylococcus aureus was the second most common organism (19.2%) being 21.7% of these methicillin-resistant. Escherichia coli was the most common isolate in children aged less than three months. ConclusionWe found a rate of true bacteremia in children similar to recent studies. Although Streptococcus pneumoniae remains the most common microorganism, its prevalence may be declining. Monitoring microbiological data in children has implications in practice, particularly in local antibiotic prescription.

Clonal lineages and antimicrobial resistance of nonencapsulated Streptococcus pneumoniae in the post-pneumococcal conjugate vaccine era in Japan

ObjectivesThe emergence and spread of nonencapsulated Streptococcus pneumoniae (NESp) is a public health concern in the post-pneumococcal conjugate vaccine era. We analyzed the prevalence, molecular characteristics, and antimicrobial resistance of NESp responsible for noninvasive infections in northern Japan. MethodsNESp isolates were identified using molecular and phenotypical methods among 4463 S. pneumoniae isolates from noninvasive infection cases during 4 study periods between January 2011 and January 2019. NESp isolates were analyzed for antimicrobial susceptibility, genotype, and virulence-associated genes. ResultsSeventy-one NESp isolates were identified (1.6% of total clinical isolates) and assigned to the null capsule clade (NCC)1 (pspK+) (94.4%) or NCC2 (aliC+/aliD+) (5.6%). The dominant sequence types (STs) were ST7502 (23.9%), ST4845 (19.7%), ST16214 (11.3%), ST11379 (9.9%), and ST7786 (7.0%). These 5 dominant STs and all 7 novel STs were related to the sporadic NESp lineage ST1106 or PMEN clone Denmark14-ST230. High non-susceptibility rates of NESp were observed for trimethoprim-sulfamethoxazole, erythromycin, and tetracycline (>92.9%), and multidrug resistance was observed in 88.7% of the NESp isolates, including all ST7502, ST4845, and ST11379 isolates. ConclusionsThe study revealed that the dominant clonal groups of NESp were associated with a high prevalence of non-susceptibility to antimicrobials in northern Japan.

Change in Pneumococcus Serotypes but not Mortality or Morbidity in Pre- and Post-13-Valent Polysaccharide Conjugate Vaccine Era: Epidemiology in a Pediatric Intensive Care Unit over 10 Years.

Pneumococcus is a common commensal and an important pathogen among children for which immunization is available. Some serotypes occasionally cause severe pneumococcal disease with high mortality and morbidity. We reviewed all pneumococcal serotypes and mortality/morbidity in a pediatric intensive care unit (PICU) following universal pneumococcal conjugate vaccine (PCV) immunization. A 13-valent PCV was introduced in the universal immunization program in late 2011 in Hong Kong. We retrospectively reviewed all pneumococcal serotypes in the pre-(2007-11) and post-(2012-16) 13-valent PCV era. There were 29 (1.9%) PICU patients with pneumococcal isolation, of which 6 died (20% motality). Serogroups 6 and 19 predominated before and Serogroup 3 after 2012. In the post-13-valent PCV era, the prevalence of pneumococcus isolation in PICU was increased from 1 to 2% (p = 0.04); Serogroup 3 was the major serotype of morbidity, despite supposedly under vaccine coverage. The majority of pneumococcus were penicillin-sensitive (94%) in the post 13-valent PCV era. All pneumococcus specimens were sensitive to cefotaxime and vancomycin. Binary logistic regression showed that there were reductions in Serogroup 6 (odds ratio [OR], 0.050; 95% confidence interval [CI], 0.004-0.574; p = 0.016) and Serogroup 19 (odds ratio [OR], 0.105; 95% confidence interval [CI], 0.014-0.786; p = 0.028) but not mortality or morbidity for patients admitted after 2012. SPD is associated with significant morbidity and mortality, despite treatment with systemic antibiotics and ICU support. The expanded coverage of 13-valent PCV results in the reduction of Serotypes 6 and 19 but not mortality/morbidity associated with SPD in the setting of a PICU.

Epidemiology of Acute Otitis Media in the Postpneumococcal Conjugate Vaccine Era.

To study the epidemiology of acute otitis media (AOM), especially the otitis-prone condition, during the pneumococcal conjugate vaccines 7 and 13 era. Six hundred and fifteen children were prospectively managed from 6 to 36 months of life during a 10-year time frame (June 2006-June 2016). All clinical diagnoses of AOM were confirmed by tympanocentesis and bacterial culture of middle ear fluid. By 1 year of age, 23% of the children experienced ≥1 episode of AOM; by 3 years of age, 60% had ≥1 episodes of AOM, and 24% had ≥3 episodes. The peak incidence occurred at 6 to 12 months of life. Multivariable analysis of demographic and environmental data revealed a significantly increased risk of AOM associated with male sex, non-Hispanic white race, family history of recurrent AOM, day care attendance, and early occurrence of AOM. Risk factors for stringently defined (tympanocentesis-confirmed) otitis proneness, in which children suffered at least 3 episodes of AOM in a 6-month period or at least 4 within a year, were male sex, day care attendance, and family history of AOM, whereas breastfeeding in the first 6 months of life was protective. Stringently defined otitis prone children were also likely to experience their first AOM episode at a younger age. The proportion of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis causing AOM had dynamic changes during the past decade. We conclude that the epidemiology but not the risk factors for AOM have undergone substantial changes since the introduction of pneumococcal conjugate vaccines.

Bacterial etiology of acute otitis media in Spain in the post-pneumococcal conjugate vaccine era

Introduction Acute otitis media (AOM) is common in children aged <3 years. A pneumococcal conjugate vaccine (PCV) (PCV7; Prevenar, Pfizer/Wyeth, USA) has been available in Spain since 2001, which has a coverage rate of 50–60% in children aged <5 years. Materials and methods Children aged ≥3 to 36 months with AOM confirmed by an ear-nose-throat specialist were enrolled at seven centers in Spain (February 2009–May 2012) (GSK study identifier: 111425). Middle-ear-fluid samples were collected by tympanocentesis or spontaneous otorrhea and cultured for bacterial identification. Culture-negative samples were further analyzed using polymerase chain reaction (PCR). Results Of 125 confirmed AOM episodes in 124 children, 117 were analyzed (median age: 17 months (range: 3–35); eight AOM episodes were excluded from analyses. Overall, 69% (81/117) episodes were combined culture- and PCR-positive for ≥1 bacterial pathogen; 44% (52/117) and 39% (46/117) were positive for Haemophilus influenzae (Hi) and Streptococcus pneumoniae (Spn), respectively. 77 of 117 episodes were cultured for ≥1 bacteria, of which 63 were culture-positive; most commonly Spn (24/77; 31%) and Hi (32/77; 42%). PCR on culture-negative episodes identified 48% Hi- and 55% Spn-positive episodes. The most common Spn serotype was 19F (4/24; 17%) followed by 19A (3/24; 13%); all Hi-positive episodes were non-typeable (NTHi). 81/117 AOM episodes (69%) occurred in children who had received ≥1 pneumococcal vaccine dose. Conclusions NTHi and Spn were the main etiological agents for AOM in Spain. Impact of pneumococcal vaccination on AOM requires further evaluation in Spain, after higher vaccination coverage rate is reached.

Risk factors for community-acquired pneumonia in children under five years of age in the post-pneumococcal conjugate vaccine era in Brazil: a case control study.

BackgroundPneumonia plays an important role in children’s morbidity and mortality. In Brazil, epidemiological and social changes occurred concomitantly with the universal introduction of the 10-valent pneumococcal conjugate vaccine. This study identified risk factors for pneumonia following the implementation of a pneumococcal vaccination program.MethodsA hospital-based, case-control study involving incident cases of pneumonia in children aged 1–59 months was conducted between October 2010 and September 2013 at a tertiary hospital in northeastern Brazil. The diagnosis of pneumonia was based on the World Health Organization (WHO) criteria. The control group consisted of children admitted to the day-hospital ward for elective surgery. Children with comorbidities were excluded. The risk factors for pneumonia that were investigated were among those classified by the WHO as definite, likely and possible. A multivariate analysis was performed including variables that were significant at p ≤ 0.25 in the bivariate analysis.ResultsThe study evaluated 407 children in the case group and 407 children in the control group. Household crowding (OR = 2.15; 95 % CI, 1,46–3,18) and not having been vaccinated against the influenza virus (OR = 3.59; 95 % CI, 2,62–4.91) were the only factors found to increase the likelihood of pneumonia. Male gender constituted a protective factor (OR = 0.53; 95 % CI, 0,39–0,72).ConclusionChanges on risk factors for pneumonia were most likely associated with the expansion of the vaccination program and social improvements; however, these improvements were insufficient to overcome inequalities, given that household crowding remained a significant risk factor. The protection provided by the influenza vaccine must be evaluated new etiological studies. Furthermore, additional risk factors should be investigated.

Bacterial prevalence and antimicrobial prescribing trends for acute respiratory tract infections.

Antimicrobials are frequently prescribed for acute respiratory tract infections (ARTI), although many are viral. We aimed to determine bacterial prevalence rates for 5 common childhood ARTI - acute otitis media (AOM), sinusitis, bronchitis, upper respiratory tract infection, and pharyngitis- and to compare these rates to nationally representative antimicrobial prescription rates for these ARTI. We performed (1) a meta-analysis of English language pediatric studies published between 2000 and 2011 in Medline, Embase, and the Cochrane library to determine ARTI bacterial prevalence rates; and (2) a retrospective cohort analysis of children age <18 years evaluated in ambulatory clinics sampled by the 2000-2010 National Ambulatory Medical Care Survey (NAMCS) to determine estimated US ARTI antimicrobial prescribing rates. From the meta-analysis, the AOM bacterial prevalence was 64.7% (95% confidence interval [CI], 50.5%-77.7%); Streptococcus pyogenes prevalence during pharyngitis was 20.2% (95% CI, 15.9%-25.2%). No URI or bronchitis studies met inclusion criteria, and 1 sinusitis study met inclusion criteria, identifying bacteria in 78% of subjects. Based on these condition-specific bacterial prevalence rates, the expected antimicrobial rescribing rate for ARTI overall was 27.4% (95% CI, 26.5%-28.3%). However, antimicrobial agents were prescribed in NAMCS during 56.9% (95% CI, 50.8%-63.1%) of ARTI encounters, representing an estimated 11.4 million potentially preventable antimicrobial prescriptions annually. An estimated 27.4% of US children who have ARTI have bacterial illness in the post-pneumococcal conjugate vaccine era. Antimicrobials are prescribed almost twice as often as expected during outpatient ARTI visits, representing an important target for ongoing antimicrobial stewardship interventions.

Etiology of Community-acquired Pneumonia in Hospitalized Children in Northern Taiwan

Pneumonia is the leading reason for hospitalization in children. The heptavalent pneumococcal conjugate vaccine was introduced in Taiwan in October 2005. There has been no comprehensive study of the etiology of childhood community-acquired pneumonia (CAP), either in the pre- or postpneumococcal conjugate vaccine era, in Taiwan. From August 2001 to July 2002, consecutive children admitted to a teaching hospital with radiologically confirmed CAP were prospectively enrolled. The following were considered indicative of infection when positive: blood or pleural effusion bacterial culture or urinary Streptococcus pneumoniae antigen test (Binax NOW), direct immunofluorescent antigen test for Chlamydia species and viruses, virus isolation and identification and viral, mycoplasmal or chlamydial serologic tests. A total of 209 children were included, and 102 children (48.8%) were male. Patients' ages ranged from 7 months to 16 years with a median of 4 years and 3 months. The combined tests identified at least 1 etiologic agent in 85.6% of all cases, including typical bacterial pathogens in 88 cases (42.1%; 86 S. pneumoniae, 1 methicillin-resistant Staphylococcus aureus and 1 Mycobacterium tuberculosis), Mycoplasma pneumoniae in 77 cases (36.8%), Chlamydia species in 24 cases (11.5%), viral etiology in 86 cases (41.1%) and mixed viral-bacterial infections in 69 cases (33%). Children with S. pneumoniae infection were significantly younger than those with Mycoplasma pneumoniae infection (P = 0.0055) or unknown etiology (P = 0.0140). S. pneumoniae, Mycoplasma pneumoniae and viruses were equally common etiologic agents of childhood CAP in Taiwan. Frequent coinfection increased the difficulty of both predicting the responsible organisms and choosing empiric antibiotics for the management of pediatric CAP.

Pediatric acute mastoiditis in the post–pneumococcal conjugate vaccine era

To determine whether the characteristics of acute mastoiditis in children have changed in the post-heptavalent pneumococcal conjugate vaccine (PCV7) era. Case series. Clinical data for all patients admitted for acute mastoiditis at an urban tertiary children's hospital from July 1, 1996, to June 30, 2009, were reviewed. Patients with a known immune deficiency or cholesteatoma were excluded. Patients were divided into pre-PCV7 (July 1996 to December 2002; n = 38) and post-PCV7 (January 2003 to June 2009; n = 58) groups. Statistical analyses were used to compare the two groups. Ninety-six children met the inclusion criteria. There was a 53% increase in admission for acute mastoiditis in the post-PCV7 era. The pre- and post-PCV7 groups had similar demographic features, presenting history, signs and symptoms, laboratory study results, and medical management. Computed tomography scan abnormalities seen in the two groups were similar except for subperiosteal abscess, which was seen more frequently in the post-PCV7 group. Streptococcus pneumoniae was the most common pathogen isolated in both groups. The patients in the post-PCV7 group had shorter hospital stays, despite undergoing more extensive surgery to address their disease. The number of acute mastoiditis admissions did not decrease with the widespread use of PCV7. Computed tomography findings and surgical procedures required to address acute mastoiditis indicate that the post-PCV7 group had more advanced disease. S pneumoniae remains the main pathogen in acute mastoiditis, and its nonsusceptibility to penicillin and ceftriaxone may be increasing.

Serious Bacterial Infections in Febrile Infants in the Post–Pneumococcal Conjugate Vaccine Era

The objective was to identify the epidemiology of serious bacterial infections (SBI) and the current utility of obtaining routine complete blood counts (CBC) and blood cultures to stratify infants at risk of SBI, in the study population of febrile infants in the post-heptavalent pneumococcal conjugate vaccine (PCV7) era. A cohort study with nested case-controls was undertaken at a tertiary care military hospital emergency department (ED) from December 2002 through December 2003. Irrespective of clinical findings at the initial encounter, patients were included if they were under 3 months of age and had a home or ED temperature of >or=100.4 degrees F or if they were between 3 and 24 months of age with a temperature of >or=102.3 degrees F. Data abstracted included age, temperature, peripheral white blood cell (WBC) count, and discharge diagnosis. Culture (blood, urine, and cerebrospinal fluid [CSF]) and chest radiograph (CXR) results were obtained through review of the electronic hospital archives. SBI was defined as pneumonia, urinary tract infection (UTI), meningitis, or bacteremia. A total of 985 children aged 0 to 24 months were enrolled. Fifty-five percent were male, the median age was 12 months (interquartile range = 8-17 months), and 79% had received at least one PCV7. A total of 132 cases of SBI were identified in 129 infants (13.1%): 82 pneumonias, 45 UTI, five bacteremias, and no cases of bacterial meningitis. The frequency of bacteremia was 0.7%. No statistical difference was detected in the WBC count between the SBI and non-SBI groups (13.8 +/- 5.8 and 11.7 +/- 5.6, respectively; p = 0.055). No readily available WBC cutoff on the receiver operating characteristic (ROC) curve proved to be an accurate predictor of SBI. No statistical difference was detected in mean temperature between the SBI and non-SBI groups (103.3 +/- 1.2 and 103.2 +/- 1.2 degrees F, respectively; p = 0.26), nor was there a difference noted when groups were broken down by age or height of fever. The WBC count and height of fever were not found to be accurate predictors of SBI in infants age 3 to 24 months. UTI and pneumonias made up the vast majority of SBI in this population of infants. The overall bacteremia frequency was well below 1%. This calls into question the continued utility of obtaining routine complete cell counts and blood cultures in the febrile infant in the post-PCV7 era.

Occult Bacteremia in the Post-Pneumococcal Conjugate Vaccine Era: Does the Blood Culture Stop Here?

Occult Bacteremia in the Post-Pneumococcal Conjugate Vaccine Era: Does the Blood Culture Stop Here?

Prevalence of Occult Bacteremia in Children Aged 3 to 36 Months Presenting to the Emergency Department with Fever in the Postpneumococcal Conjugate Vaccine Era

The goal of this study was to identify the prevalence of occult bacteremia (OB) in well-appearing, previously healthy children aged 3 to 36 months who present to the emergency department (ED) with fever without source in the post-pneumococcal conjugate vaccine (PCV) era. This was a retrospective cohort study of children presenting to an urban pediatric ED between July 1, 2004, and June 30, 2007. Children were included if they were aged 3 to 36 months, febrile, and previously healthy; had no source of infection on examination; had a blood culture drawn; and were discharged from the ED. Outcome measures were rates of OB and contaminant rates. A total of 8,408 children met all inclusion criteria. There were 21 true-positives, yielding an OB rate of 0.25% (95% confidence interval [CI] = 0.16% to 0.37%). There were 159 contaminant cultures yielding a contaminant rate of 1.89% (95% CI = 1.61% to 2.19%), or a ratio of 7.6 contaminants for each true-positive. There were 14 included patients who grew Streptococcus pneumoniae from the blood, for a rate of 0.17% (95% CI = 0.09% to 0.27%). Given the current rate of OB in the post-PCV era, it may no longer be cost-effective to send blood cultures on well-appearing, previously healthy children aged 3 to 36 months who have fever without source.

Seasonal Invasive Pneumococcal Disease in Children: Role of Preceding Respiratory Viral Infection

Our objective was to demonstrate correlations between invasive pneumococcal disease in children and circulating respiratory viruses. This retrospective study included 6 winter respiratory viral seasons (2001-2007) in Intermountain Healthcare, an integrated health system in the Intermountain West, including Primary Children's Medical Center in Salt Lake City, Utah. Children <18 years of age who were hospitalized with either invasive pneumococcal disease in any Intermountain Healthcare facility or culture-confirmed invasive pneumococcal disease at Primary Children's Medical Center were included. We analyzed the correlation between invasive pneumococcal disease and circulating respiratory viruses. A total of 435 children with invasive pneumococcal disease and 203 with culture-confirmed invasive pneumococcal disease were hospitalized in an Intermountain Healthcare facility or Primary Children's Medical Center during the study period. During the same period, 6963 children with respiratory syncytial virus, 1860 with influenza virus, 1459 with parainfluenza virus, and 818 with adenoviruses were evaluated at Primary Children's Medical Center. A total of 253 children with human metapneumovirus were identified during the last 5 months of the study. There were correlations between invasive pneumococcal disease and seasonal respiratory syncytial virus, influenza virus, and human metapneumovirus activity. The correlation with invasive pneumococcal disease was strong up to 4 weeks after respiratory syncytial virus activity. For influenza virus and human metapneumovirus, the correlations were strong at 2 weeks after activity of these viruses. Pneumonia was the most common clinical disease associated with culture-confirmed invasive pneumococcal disease, mostly attributable to serotypes 1, 19A, 3, and 7F. In the post-pneumococcal conjugate vaccine era, seasonal increases in respiratory syncytial virus, influenza virus, and human metapneumovirus infections in children were associated with increased pediatric admissions with invasive pneumococcal disease, especially pneumonia caused by nonvaccine serotypes.

An Analysis of Pediatric Blood Cultures in the Postpneumococcal Conjugate Vaccine Era in a Community Hospital Emergency Department

Blood cultures are commonly included in the evaluation of febrile children younger than 3 years without focal source of infection. Clinicians treat patients with a positive blood culture before final identification of the organism. Their treatment might include reevaluation in the emergency department (ED), additional tests, parenteral antibiotics, and hospital admission even for children who ultimately have false-positive (FP) blood cultures. The advent of pneumococcal conjugate vaccine (PCV) has made occult bacteremia less common, decreasing the likelihood that a positive blood culture result before final organism identification will be a true pathogen. This study will identify the characteristics of patients with FP blood cultures in the post-PCV era. Charts were reviewed of all children ages 1 to 36 months with a temperature of at least 38.08 degrees C who had a blood culture obtained in our community hospital ED from January 1997 to January 2005. Bacteria grew in 106 (3.5%) out of 2971 blood cultures. True positives (TPs), defined as true pathogens, had a prevalence of 0.7%, representing 19.8% of positives. FPs, defined as contaminants, occurred in 2.8% of cultures, representing 80.2% of positives. Patients with FP cultures had lower mean white blood cell (WBC) counts (10.51 x 10(9)/L vs. 16.95 x 10(9)/L; P = 0.0001) and lower mean presenting temperatures (38.8 degrees C vs. 39.4 degrees C; P = 0.005). FPs had longer time to positivity (34.6 vs. 17.7 hours; P = 0.001) than TPs. A culture with a Gram stain suggestive of a contaminant, time to positivity greater than 24 hours and a WBC of less than 15 x 10(9)/L had a PPV for an FP of 97%. When analysis was restricted to well-appearing children age 2 to 36 months with temperature of more than 39 degrees C without focal source of infection who were discharged from the ED, these three criteria had a PPV for an FP of 100%. In these highly febrile children, the FPs had significantly lower WBCs (9.14 x 10(9)/L vs. 22.84 x 10(9)/L; P = 0.0001) and longer time topositivity (33.4 vs. 19.8 hours; P = 0.007) than TPs. The likelihood of obtaining FP cultures increased after the introduction of PCV from 62.5% to 87.8% odds ratio, 4.3; 95%confidence internal, 1.44-13.38). In the post-PCV era, the majority of blood culture results will be FPs. FP cultures are predictable in febrile children with WBC counts less than 15.00 x 10(9)/L, time to positivity of more than 24 hours, and a Gram stain result suggestive of a contaminant. Prospective studies applying these criteria to the at-risk population for occult bacteremia are indicated.