Identifying transmission routes of Streptococcus pneumoniae and sources of acquisitions in high transmission communities.

Identifying the transmission sources and reservoirs of Streptococcus pneumoniae (SP) is a long-standing question for pneumococcal epidemiology, transmission dynamics, and vaccine policy. Here we use serotype to identify SP transmission and examine acquisitions (in the same household, local community, and county, or of unidentified origin) in a longitudinal cohort of children and adults from the Navajo Nation and the White Mountain Apache American Indian Tribes. We found that adults acquire SP relatively more in the household than other age groups, and children 2-8 years old typically acquire in their own or surrounding communities. Age-specific transmission probability matrices show that transmissions within household were mostly seen from older to younger siblings. Outside the household, children most often transmit to other children in the same age group, showing age-assortative mixing behavior. We find toddlers and older children to be most involved in SP transmission and acquisition, indicating their role as key drivers of SP epidemiology. Although infants have high carriage prevalence, they do not play a central role in transmission of SP compared with toddlers and older children. Our results are relevant to inform alternative pneumococcal conjugate vaccine dosing strategies and analytic efforts to inform optimization of vaccine programs, as well as assessing the transmission dynamics of pathogens transmitted by close contact in general.

Impact of the Hajj on pneumococcal transmission.

Over two million Muslim pilgrims assemble annually in Mecca and Medina, Saudi Arabia, to complete the Hajj. The large number of people in a crowded environment increases the potential for pneumococcal carriage amplification. We evaluated pneumococcal carriage prevalence with four cross-sectional studies conducted at beginning-Hajj (Mecca) and end-Hajj (Mina) during 2011 and 2012. A questionnaire was administered and a nasopharyngeal swab was collected. The swab was tested for pneumococcus, serotype and antibiotic resistance. A total of 3203 subjects (1590 at beginning-Hajj and 1613 at end-Hajj) originating from 18 countries in Africa or Asia were enrolled. The overall pneumococcal carriage prevalence was 6.0%. There was an increase in carriage between beginning-Hajj and end-Hajj cohorts for: overall carriage (4.4% versus 7.5%, prevalence ratio (PR) 1.7, 95% CI 1.3-2.3), and carriage of 23-valent pneumococcal polysaccharide vaccine serotypes (2.3% versus 4.1%, PR 1.8, 95% CI 1.2-2.7), 13-valent pneumococcal conjugate vaccine (PCV) serotypes (1.1% versus 3.6%, PR 3.2, 95% CI 1.9-5.6), 10-valent PCV serotypes (0.6% versus 1.6%, PR 2.6, 95% CI 1.2-5.3), antibiotic non-susceptible isolates (2.5% versus 6.1%, PR 2.5, 95% CI 1.7-3.6) and multiple non-susceptible isolates (0.6% versus 2.2%, PR 3.8, 95% CI 1.8-7.9). Fifty-two different serotypes were identified, most commonly serotypes 3 (17%), 19F (5%) and 34 (5%). These results suggest that the Hajj may increase pneumococcal carriage-particularly conjugate vaccine serotypes and antibiotic non-susceptible strains, although the exact mechanism remains unknown. The Hajj may therefore provide a mechanism for the global distribution of pneumococci.

Variation at the capsule locus, cps, of mistyped and non-typable Streptococcus pneumoniae isolates.

The capsule polysaccharide locus (cps) is the site of the capsule biosynthesis gene cluster in encapsulated Streptococcus pneumoniae. A set of pneumococcal samples and non-pneumococcal streptococci from Denmark, the Gambia, the Netherlands, Thailand, the UK and the USA were sequenced at the cps locus to elucidate serologically mistyped or non-typable isolates. We identified a novel serotype 33B/33C mosaic capsule cluster and previously unseen serotype 22F capsule genes, disrupted and deleted cps clusters, the presence of aliB and nspA genes that are unrelated to capsule production, and similar genes in the non-pneumococcal samples. These data provide greater understanding of diversity at a locus which is crucial to the antigenic diversity of the pathogen and current vaccine strategies.

Use of serology and urine antigen detection to estimate the proportion of adult community-acquired pneumonia attributable to Streptococcus pneumoniae.

Streptococcus pneumoniae is a common cause of community-acquired pneumonia (CAP) but existing diagnostic tools have limited sensitivity and specificity. We enrolled adults undergoing chest radiography at three Indian Health Service clinics in the Southwestern United States and collected acute and convalescent serum for measurement of PsaA and PspA titres and urine for pneumococcal antigen detection. Blood and sputum cultures were obtained at the discretion of treating physicians. We compared findings in clinical and radiographic CAP patients to those in controls without CAP. Urine antigen testing showed the largest differential between CAP patients and controls (clinical CAP 13%, radiographic CAP 17%, control groups 2%). Serological results were mixed, with significant differences between CAP patients and controls for some, but not all changes in titre. Based on urine antigen and blood culture results, we estimated that 11% of clinical and 15% of radiographic CAP cases were due to pneumococcus in this population.

Measuring the incidence of adult community-acquired pneumonia in a Native American community.

Few population-based studies have investigated the epidemiology of adult community-acquired pneumonia (CAP). We aimed to determine the incidence of CAP in a population at high-risk for pneumococcal disease and to evaluate a standardized method for interpreting chest radiographs adapted from the World Health Organization paediatric chest radiograph interpretation guidelines. We reviewed radiology records at the two healthcare facilities serving the White Mountain Apache tribe to identify possible pneumonia cases > or =40 years of age. We categorized patients with clinical criteria and a physician diagnosis of pneumonia as clinical CAP and those with clinical criteria and an acute infiltrate as radiographic CAP. We identified 100 (27/1000 person-years) and 60 (16/1000 person-years) episodes of clinical and radiographic CAP, respectively. The incidence of CAP increased with age. Both radiographic and clinical CAP were serious illnesses with more than half of patients hospitalized. Our case definitions and methods may be useful for comparing data across studies and conducting vaccine trials.

The prevalence and incidence of end-stage renal disease in Native American adults on the Navajo reservation.

Whereas members of the Navajo Nation are at high risk for diabetes mellitus, there are no recent published estimates of the burden of end-stage renal disease (ESRD), an important sequela of diabetes, on the Navajo Nation, a 16 million acre area in Arizona, New Mexico, and Utah with more than 200 000 tribal members. We used data from the US Renal Data System to estimate the prevalence and incidence of ESRD among Native American adults (>/=18 years) living on the Navajo Nation. For comparison, we estimated the prevalence and incidence of ESRD among all adults in the US, all Native American adults in the US, and Native American adults living in Arizona, New Mexico, Utah, and Colorado excluding those living on the Navajo Nation. The age-adjusted prevalence of ESRD in the Native American adults on the Navajo Nation was 0.63%, which was higher than in the US adults (0.19%, P<0.0001) and among the Native American adults in the US (0.36%, P<0.0001), but lower than among the other Native American adults in the Southwest (0.89%, P<0.0001). The age-adjusted incidence of ESRD in the Native American adults on the Navajo Nation was 0.11%, which was also higher than in the US adults (0.045%, P<0.0001) and among the Native American adults in the US (0.073%, P<0.0009), but lower than among the other Native American adults in the Southwest (0.17%, P<0.0003). The reasons behind these disparities merit further study.

Evaluation of the indirect effects of a pneumococcal vaccine in a community-randomized study.

When a sufficiently high proportion of a population is immunized with a vaccine, reduction in secondary transmission of disease can confer significant protection to unimmunized population members. We propose a straightforward method to estimate the degree of this indirect effect of vaccination in the context of a community-randomized vaccine trial. A conditional logistic regression model that accounts for within-randomization unit correlation over time is described, which models risk of disease as a function of community-level covariates. The approach is applied to an example data set from a pneumococcal conjugate vaccine study, with study arm and immunization levels forming the covariates of interest for the investigation of indirect effects.

Early-onset neonatal sepsis in the era of group B streptococcal prevention.

OBJECTIVE: To determine whether intrapartum antibiotic prophylaxis for neonatal group B streptococcal (GBS) disease has resulted in an increased rate of non-GBS or antibiotic-resistant early-onset invasive neonatal disease. METHODS: Maternal and infant chart review of all infants with bacteria other than GBS isolated from blood or spinal fluid in 1996 through 1999 in 19 hospitals (representing 81% of in-state births to state residents) throughout Connecticut. Suspected cases were identified through clinical microbiology laboratory records or through International Classification of Diseases, Ninth Revision codes when microbiology records were incomplete. RESULTS: Ninety-four cases of non-GBS early-onset sepsis or meningitis were detected between 1996 and 1999. The rate of GBS-related early-onset infection (days 0-6 of life) dropped from 0.61/1000 to 0.23/1000 births, but the annual rate of non-GBS sepsis remained steady, ranging from 0.65 to 0.68/1000 during the surveillance period. There was an increase in the proportion of Escherichia coli infections that were ampicillin resistant between 1996 and 1998, but the proportion decreased. in 1999 CONCLUSION: There was no increase in the incidence of non-GBS early-onset neonatal infections between 1996 and 1999. Fluctuations in the annual incidence of E coli infections, including ampicillin-resistant infections, suggest the need for continuation of surveillance in Connecticut and expansion to monitor larger populations.

Randomized trial of presumptive sexually transmitted disease therapy during pregnancy in Rakai, Uganda.

OBJECTIVE: The purpose of this study was to assess presumptive sexually transmitted disease treatment on pregnancy outcome and HIV transmission. STUDY DESIGN: In a randomized trial in Rakai District, Uganda, 2070 pregnant women received presumptive sexually transmitted disease treatment 1 time during pregnancy at varying gestations, and 1963 control mothers received iron/folate and referral for syphilis. Maternal-infant sexually transmitted disease/HIV and infant outcomes were assessed. Intent-to-treat analyses estimated adjusted rate ratios and 95% confidence intervals. RESULTS: Sexually transmitted diseases were reduced: Trichomonas vaginalis (rate ratio, 0.28; 95% CI, 0.18%-0.49%), bacterial vaginosis (rate ratio, 0.78; 95% CI, 0.69-0.87), Neisseria gonorrhoeae /Chlamydia trachomatis (rate ratio, 0.43; 95% CI, 0.27-0.68), and infant ophthalmia (rate ratio, 0.37; 95% CI, 0.20-0.70). There were reduced rates of neonatal death (rate ratio, 0.83; 95% CI, 0.71-0.97), low birth weight (rate ratio, 0.68; 95% CI, 0.53-0.86), and preterm delivery (rate ratio, 0.77; 95% CI, 0.56-1.05); but there were no effects on maternal HIV acquisition or perinatal HIV transmission. CONCLUSION: Reductions of maternal sexually transmitted disease improved pregnancy outcome but not maternal HIV acquisition or perinatal HIV transmission.

Design of a group-randomized Streptococcus pneumoniae vaccine trial.

A group-randomized, double-masked, phase III trial of a Streptococcus pneumoniae conjugate vaccine is being conducted in American Indian populations in the southwestern United States. Approximately 9000 infants will be enrolled in the primary efficacy cohort with vaccine allocation determined by community of residence. The trial is designed to continue until 48 cases of invasive pneumococcal disease due to vaccine serotypes have accumulated. Thirty-eight geographically and socially distinct areas were randomized within blocks formed by population size and geographic location. This design affords the opportunity to capture the effects of herd immunity (indirect effects) by estimating the impact of the vaccine intervention on nonimmunized infants. Group-randomized trials have challenging design and analysis features, many of which are discussed here in the context of the first such trial designed to lead to licensure of a drug or biologic in the United States.

Invasive group A streptococcal infection and nonsteroidal antiinflammatory drug use among children with primary varicella.

OBJECTIONS: To test the hypothesis that nonsteroidal antiinflammatory drug use increases the risk of necrotizing soft tissue infections and, secondarily, all invasive group A streptococcal (GAS) infections in children with primary varicella infection. METHODS: We conducted a prospective, multicenter case-control study among children <19 years old. Cases were children hospitalized with primary varicella complicated by invasive GAS infection or necrotizing soft tissue infection identified by a network of 45 pediatric infectious disease specialists located throughout the United States. Controls were children with uncomplicated primary varicella residing in the same communities as the cases. Data on medical history, clinical features of the varicella infection, signs and symptoms of infectious complications, and medication use were collected by structured telephone interviews. Univariate and multivariate matched odds ratios were calculated using conditional logistic regression. RESULTS: Between June 1996 and September 1998, 52 cases of invasive GAS infection, including 21 with necrotizing soft tissue infection, and 172 controls with uncomplicated primary varicella were enrolled. Risk of invasive GAS infection was increased among children who were nonwhite (multivariate odds ratio [OR] 3.8, 95% confidence interval [CI]: 1.4-11), living in low-income households (OR 5.1, 95% CI: 1.7-15), exposed to varicella at home (OR 6.4, 95% CI: 2.6-16), or had a persistent high fever (OR 9.6, 95% CI: 2.8-33). Antipyretic regimen was associated with several measures of varicella illness severity among the controls. The risk of necrotizing soft tissue infection was not associated with the use of ibuprofen before the development of signs or symptoms of this complication (OR 1.3, 95% CI: 0.33-5.3). Risk of any invasive GAS infection was increased among children who had received ibuprofen (OR 3.9, 95% CI: 1.3-12), but not acetaminophen (OR 1.2, 95% CI: 0.50-3.0). However, there was no evidence of increasing risk with increasing duration of ibuprofen use. Subgroup analyses revealed that the risk of invasive GAS infection was increased only among children who had received both acetaminophen and ibuprofen. CONCLUSIONS: These data do not support the hypothesis that nonsteroidal antiinflammatory drugs, or ibuprofen in particular, increase the risk of necrotizing GAS infections. A statistically significant association was observed between nonnecrotizing invasive GAS infection and ibuprofen use; however, because of potential confounding, the meaning of this unexpected result is unclear. Nonetheless, these data suggest that parents use ibuprofen or ibuprofen together with acetaminophen to treat high fever and severe illness, which seems to identify children at high risk for invasive GAS infection.

Evaluation of a medium (STGG) for transport and optimal recovery of Streptococcus pneumoniae from nasopharyngeal secretions collected during field studies.

Field studies of Streptococcus pneumoniae (pneumococci) nasopharyngeal (NP) colonization are hampered by the need to directly plate specimens in order to ensure isolate viability. A medium containing skim milk, tryptone, glucose, and glycerin (STGG) has been used to transport and store NP material, but its ability to preserve pneumococci has not been evaluated. Our objective was to qualitatively and semiquantitatively evaluate the ability of STGG to preserve pneumococci in NP secretions. Entwined duplicate calcium alginate NP swab samples were obtained from children. One swab was plated directly onto a gentamicin blood agar plate; the other was placed in STGG. Growth from the directly plated specimen was compared with growth from an STGG aliquot immediately cultured or stored at -70 degrees C for 9 weeks, -20 degrees C for 9 weeks, or 4 degrees C for 5 days. Of 186 specimens, 96 (52%) were positive for pneumococci from the direct plating; 94 (98%) of these were positive from the fresh STGG specimen. Pneumococci were recovered from all 38 positive specimens frozen at -70 degrees C, all 18 positive specimens frozen at -20 degrees C, and 18 of 20 positive specimens stored at 4 degrees C. Recovery of pneumococci after storage of NP material in STGG medium at -70 degrees C is at least as good as that from direct plating. Storage at -20 degrees C is also acceptable. Storage at 4 degrees C for 5 days is not ideal.

Safety and immunogenicity of heptavalent pneumococcal vaccine conjugated to CRM(197) among infants with sickle cell disease. Pneumococcal Conjugate Vaccine Study Group.

OBJECTIVES: To determine the immunogenicity and safety of heptavalent pneumococcal polysaccharide vaccine (serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F) conjugated to CRM(197) (7-valent conjugate pneumococcal vaccine [7VPnC]) among infants with sickle cell disease (SCD) and a comparison group of infants without SCD (non-SCD). DESIGN: Two cohorts of infants were enrolled and received open-label doses of 7VPnC vaccine; infants enrolled before 2 months of age received 7VPnC vaccine at 2, 4, and 6 months of age followed by 23-valent pneumococcal polysaccharide vaccine (PS-23) at 24 months of age for those infants with SCD (schedule A), and infants enrolled between 2 and 12 months of age received 7VPnC at 12 months of age followed by PS-23 at 24 months of age for infants with SCD (schedule B). Safety data were collected for 3 days after each dose of vaccine. Antibody concentrations were measured to each of the 7VPnC serotypes by enzyme-linked immunosorbent assay before each vaccine dose and 1 month after the last 7VPnC dose and the PS-23 vaccine dose. RESULTS: Forty-five infants (34 SCD and 11 non-SCD) were vaccinated according to schedule A and 16 infants (13 SCD and 3 non-SCD) according to schedule B. The 7VPnC vaccine was highly immunogenic for all serotypes among infants with and without SCD who received 3 doses of vaccine according to schedule A: depending on serotype, 89% to 100% achieved antibody concentrations above.15 microg/mL and 56% to 100% achieved antibody concentrations above 1.0 microg/mL. Among infants immunized according to schedule B, a single dose of 7VPnC vaccine resulted in antibody concentrations above.15 microg/mL in 53% to 92% by serotype and above 1.0 microg/mL in 31% to 71% by serotype. A single dose of PS-23 resulted in dramatic increases in the antibody concentrations to all serotypes regardless of 1- or 3-dose priming. There was no difference in the reactogenicity of the 7VPnC vaccine between those with and without SCD. There were no serious reactions to the 7VPnC or PS-23 vaccines, even among those with high antibody concentrations before immunization. CONCLUSIONS: Infants with SCD respond to 7VPnC vaccine with antibody concentrations that are at least as high as infants without SCD. Infants immunized with 7VPnC vaccine at 2, 4, and 6 months of age developed antibody concentrations in the same range as those achieved among infants without SCD enrolled in a large trial that demonstrated vaccine efficacy against invasive disease. Significant rises were seen in antibody concentrations to all 7VPnC serotypes after the PS-23 booster in children receiving schedule A or B.

Toward elimination of Haemophilus influenzae type B carriage and disease among high-risk American Indian children.

OBJECTIVES: This report describes the epidemiology of Haemophilus influenzae type b (Hib) invasive disease and oropharyngeal colonization among Navajo and White Mountain Apache children younger than 7 years in an era of widespread immunization. METHODS: We conducted active surveillance for invasive H influenzae disease from 1992 to 1999 and an oropharyngeal carriage study from 1997 to 1999. The predominant vaccine used was PedvaxHib. RESULTS: The average annual incidence of invasive Hib disease among children younger than 24 months was 22 cases per 100,000. Of 381 children younger than 7 years, only 1 (0.3%; 95% confidence interval = 0.0%, 1.3%) was colonized with Hib; 370 (97%) had received 2 or more doses of Hib conjugate vaccine. CONCLUSIONS: Among Navajo and White Mountain Apache children, Hib conjugate vaccines have led to a sustained reduction in invasive Hib disease and a reduction in oropharyngeal Hib carriage. The disease incidence among children younger than 24 months remains 20 times higher than in the general US population. Hib elimination will require additional characterization of colonization and disease in these high-risk populations.

Severe pneumococcal pneumonia in previously healthy children: the role of preceding influenza infection.

An outbreak of severe pneumococcal pneumonia among children occurred in Iowa from November 1995 through January 1996. An associated outbreak of influenza disease was predominantly caused by influenza A (H1N1) for the first time since 1989. We conducted a case-control study to determine whether preceding influenza infection was directly associated with pneumococcal illness. We identified 13 children with severe pneumococcal pneumonia. Patients were more likely than control subjects to report experiencing an influenza-like illness in the 7-28 days preceding admission (matched odds ratio [OR], 12.4; 95% confidence interval [CI], 1.7-306). Likewise, family members of patients were more likely than those of control subjects to report experiencing an influenza-like illness in the 28 days preceding their admission date (OR, 2.6; 95% CI, 1.0-6. 3). Patients were more likely than control subjects to have a positive influenza A (H1N1) convalescent serology (matched OR, 3.7; 95% CI, 1.0-18.1). This study provides direct and indirect evidence that influenza infection led to severe pneumococcal pneumonia among these children. Prevention of pneumococcal disease should be included among the potential benefits of influenza vaccination.

Impact of azithromycin on oropharyngeal carriage of group A Streptococcus and nasopharyngeal carriage of macrolide-resistant Streptococcus pneumoniae.

BACKGROUND: Invasive group A streptococcal (GAS) infections are a cause of serious morbidity and high mortality. There is a need for a simple, effective antimicrobial regimen that could be used to prevent invasive GAS disease in high risk situations. To assess azithromycin as a chemoprophylactic agent, we evaluated its efficacy for eradication of oropharyngeal (OP) GAS and its impact on the nasopharyngeal (NP) colonization rate of macrolide-resistant Streptococcus pneumoniae. METHODS: We obtained OP and NP swabs for GAS and pneumococcus culture, respectively, from 300 schoolmates of a child with an invasive GAS infection. GAS culture-positive students were treated with daily azithromycin (12 mg/kg/day) for 5 days. We obtained follow-up OP and NP swabs at 9 (Day 17) and 24 (Day 32) days post-treatment from those students identified as GAS carriers on Day 0 and determined macrolide susceptibility of GAS and pneumococcal isolates. RESULTS: Of the 300 students swabbed 152 (50%) carried GAS in their oropharynx. On Day 17, efficacy of azithromycin for GAS eradication was 95% (140 of 147) for all students. NP colonization rates for pneumococci decreased from 46% (67 of 146) to 12% (17 of 144; P < 0.001) by Day 17 and to 20% (27 of 137; P < 0.001) by Day 32. The prevalence of erythromycin-resistant pneumococcal isolates increased from 2% (3 of 146) to 4% (6 of 144) by Day 17 and to 8% (11 of 137; P = 0.04) by Day 32. CONCLUSIONS: Azithromycin is an effective short course regimen for eradication of oropharyngeal GAS. However, azithromycin selected for macrolide-resistant strains of pneumococci. These findings highlight the importance of determining the appropriate circumstances for antimicrobial prophylaxis to prevent invasive GAS infections.

Epidemic of pediatric deaths from acute renal failure caused by diethylene glycol poisoning. Acute Renal Failure Investigation Team.

CONTEXT: Contaminated pharmaceutical products can result in substantial morbidity and mortality and should be included in the differential diagnosis of deaths of unknown origin. OBJECTIVE: To investigate an outbreak of deaths among children from acute renal failure in Haiti to determine the etiology and institute control measures. DESIGN: Case-control study, cohort study, and laboratory toxicologic evaluation. SETTING: Pediatric population of Haiti. PARTICIPANTS: Cases were defined as Haitian residents younger than 18 years with idiopathic anuria or severe oliguria for 24 hours or longer. Febrile hospitalized children without renal failure were enrolled as control subjects. MAIN OUTCOME MEASURE: The odds of exposure to suspected etiologic agents among cases and controls. RESULTS: We identified 109 cases of acute renal failure among children. The clinical syndrome included renal failure, hepatitis, pancreatitis, central nervous system impairment, coma, and death. Of 87 patients with follow-up information who remained in Haiti for treatment, 85 (98%) died; 3 (27%) of 11 patients transported to the United States for intensive care unit management died before hospital discharge. A locally manufactured acetaminophen syrup was highly associated with disease (odds ratio, 52.7; 95% confidence interval, 15.2-197.2). Diethylene glycol (DEG) was found in patients' bottles in a median concentration of 14.4%. The median estimated toxic dose of DEG was 1.34 mL/kg (range, 0.22-4.42 mL/kg). Glycerin, a raw material imported to Haiti and used in the acetaminophen formulation, was contaminated with 24% DEG. CONCLUSIONS: An epidemic of severe systemic toxicity and deaths from DEG-contaminated acetaminophen syrup occurred in Haiti. Good manufacturing practice regulations should be used by all pharmaceutical manufacturers to prevent such tragedies.