Biomedical subjects

Katherine L O'Brien

Publications and source records attributed to Katherine L O'Brien.

26 records · Page 2Linked to original sources

PubMed2003

Invasive pneumococcal infections in children with sickle cell disease in the era of penicillin prophylaxis, antibiotic resistance, and 23-valent pneumococcal polysaccharide vaccination.

Rates and severity of pneumococcal infections in children with sickle cell disease were examined before licensure of pneumococcal-conjugated vaccine (PVC). Rates of peak invasive infection rates in 1-year-old children with hemoglobin SS and mortality in those 0 to 10 years of age were 36.5 to 63.4 and 1.4 to 2.8 per 1000 person-years, respectively (>10 and 100 times as frequent as in the general population). Overall, 71% of serotyped isolates (n=80) were PVC serotypes and 71% of nonvaccine serotype strains were penicillin-sensitive. Clinical presentation in children with hemoglobin SS (n=71; more with hypotension) and hemoglobin SC (n=18; more with acute chest syndrome, otitis media) differed. Penicillin nonsusceptibility (38% of isolates) varied between geographic study sites. Penicillin prophylaxis appeared less effective against intermediate and resistant strains. Of all infected children, meningitis developed in 20% and 15% died (hemoglobin SS, n=15 and 11; hemoglobin SC, n=1 each). Factors associated with death included age >4 years (58%), serotype 19F, and not being followed by a hematologist (42% each). The pneumococcal-polysaccharide vaccine was 80.4% effective within 3 years after vaccination (95% CI, 39.7, 93.6). Children with sickle cell disease of all ages may benefit from PVC boosted with polysaccharide vaccination.

Anemia, Sickle Cell↗

PubMed2003

Report from a WHO working group: standard method for detecting upper respiratory carriage of Streptococcus pneumoniae.

BACKGROUND: Numerous studies evaluating the efficacy of conjugate pneumococcal vaccines are being conducted or planned throughout the world. Some of these studies are evaluating the effect of vaccine on nasopharyngeal (NP) carriage. METHODS: The World Health Organization established a Working Group composed of representatives from these trials and other NP colonization experts to establish core, standardized methods for the study of pneumococcal NP colonization that could be used in these trials. The intent was to reduce or eliminate variability in key methods which themselves could contribute to variability of observed pneumococcal NP colonization. In this way variability of vaccine effects between trials on NP colonization could more easily be analyzed for population or vaccine differences without the confounding effect caused by differences in study methodology. RESULTS: This paper presents the evidence base supporting the need for standardized NP colonization study methods, the methods themselves (Core Consensus Methods found in the electronic version of this article at www.pidj.com and on the WHO website at http://www.who.int/vaccines-research/rd/docsrd.shtml), including collection techniques, culture media, equipment, serotyping, storage of specimens and transport of isolates agreed on by the Working Group as well as a discussion of research priorities. CONCLUSIONS: The Core Consensus Methods provide a common methodology to conduct pneumococcal NP colonization studies with minimum interstudy method variability. The intention is to allow more meaningful comparisons of study results from conjugate pneumococcal vaccine trials.

Bacteriological Techniques↗

PubMed2003

Report from a WHO Working Group: standard method for detecting upper respiratory carriage of Streptococcus pneumoniae.

BACKGROUND: Numerous studies evaluating the efficacy of conjugate pneumococcal vaccines are being conducted or planned throughout the world. Some of these studies are evaluating the effect of vaccine on nasopharyngeal (NP) carriage. METHODS: The World Health Organization established a Working Group comprised of representatives from these trials and other NP colonization experts to establish core, standardized methods for the study of pneumococcal NP colonization that could be used in these trials. The intent was to reduce or eliminate variability in key methods which themselves could contribute to variability of observed pneumococcal NP colonization. In this way variability of vaccine effects between trials on NP colonization could more easily be analyzed for population or vaccine differences without the confounding effect caused by differences in study methodology. RESULTS: This paper presents the evidence base supporting the need for standardized NP colonization study methods, the methods themselves (Core Consensus Methods), including collection techniques, culture media, equipment, serotyping, storage of specimens and transport of isolates agreed on by the Working Group as well as a discussion of research priorities. CONCLUSIONS: The Core Consensus Methods provide a common methodology to conduct pneumococcal NP colonization studies with minimum interstudy method variability. The intention is to allow more meaningful comparisons of study results from conjugate pneumococcal vaccine trials.

Age Distribution↗

PubMed2003

Impact of intrapartum antibiotics on the care and evaluation of the neonate.

BACKGROUND: Management of infants whose mothers receive intrapartum antibiotic prophylaxis (IAP) is controversial. In 1996 consensus guidelines for prevention of neonatal Group B streptococcal disease included an algorithm for management of infants whose mothers received IAP. To assess practices for testing and treatment of infants, we evaluated a population-based sample of deliveries to see whether excessive evaluation and treatment occurs after IAP. METHODS: Medical records for 869 deliveries in Connecticut during 1996 were sampled. IAP was administered in 96 full term deliveries. We excluded infants <37 weeks and those with intrapartum fever. We reviewed hospital records for infants born after IAP (n = 81) and a random sample of those not exposed (n = 180). Analyses were conducted with sample weights to account for unequal probability of selection. RESULTS: Infants whose mothers received IAP were more likely to have complete blood counts, (26% vs. 9% P = 0.05) but were no more likely to receive antibiotics in the first week of life (P = 0.48), have an intravenous catheter placed (P = 0.83), or to have other invasive procedures. Mean length of hospital stay was 6 h longer for infants born by vaginal delivery to mothers who had IAP (47.0 h) than for those without IAP (41.3 h) (P = 0.06). CONCLUSION: Despite concerns that IAP guidelines would result in excessive neonatal evaluations, infants sampled whose mothers received IAP were not more likely to undergo invasive procedures or to receive antibiotics. Consistent with the guidelines, collection of complete blood counts was more common among such infants.

Adult↗

PubMed2002

Epidemiology of invasive group a streptococcus disease in the United States, 1995-1999.

Severe invasive group A streptococcal (GAS) disease is believed to have reemerged during the past 10-20 years. We conducted active, laboratory, population-based surveillance in 5 US states (total population, 13,214,992). From 1 July 1995 through 31 December 1999, we identified 2002 episodes of invasive GAS (3.5 cases per 100,000 persons). Rates varied by age (higher among those <2 or >/=65 years old), surveillance area, and race (higher among black individuals) but did not increase during the study period. The 5 most common emm types (1, 28, 12, 3, and 11) accounted for 49.2% of isolates; newly characterized emm types accounted for 8.9% of isolates. Older age; presence of streptococcal toxic shock syndrome, meningitis, or pneumonia; and infection with emm1 or emm3 were all independent predictors of death. We estimate that 9600-9700 cases of invasive GAS disease occur in the United States each year, resulting in 1100-1300 deaths.

Antigens, Bacterial↗

PubMed2002

Integrated monitoring of a new group B streptococcal disease prevention program and other perinatal infections.

OBJECTIVE: To determine levels of prenatal screening for several infections, intrapartum recognition of risk factors, and prophylaxis against mother-to-child transmission of group B streptococcus. METHODS: Review of stratified random sample of hospital records for deliveries in Connecticut during 1996. SUDAAN analysis was used to adjust for the complex survey design, and weighting adjusted for the probability of being sampled and nonresponse. RESULTS: Of 992 records requested, 868 (88%) were abstracted and analyzed. Thirty-six percent of women had prenatal screening for group B streptococcus and 26% had been tested for human immunodeficiency virus (HIV), while 97-99% of women had been screened prenatally for hepatitis B surface antigen, rubella, and syphilis. Of those women tested, 17% were detected as group B streptococcus carriers, and 78% of these received intrapartum antibiotic prophylaxis. Among women who were not screened for group B streptococcus prenatally, 22% met risk-based criteria for prophylaxis, but only 45% of these received intrapartum prophylaxis. Among unscreened women with a risk factor, those with shorter hospital stays prior to delivery, admitted on evening or night shifts, or who delivered on the weekend were significantly less likely to receive intrapartum prophylaxis. CONCLUSION: In 1996, the majority of women who delivered in Connecticut were not tested prenatally for group B streptococcus and the majority of those not tested in whom there was an indication for prophylaxis were not treated. Compliance with group B streptococcus prevention recommendations can be improved through increased prenatal testing and/or better recognition of risk-based criteria for intrapartum prophylaxis.

Anti-Bacterial Agents↗

PubMed2002

Respiratory syncytial virus infection in Navajo and White Mountain Apache children.

OBJECTIVE: The hospitalization rate for bronchiolitis of any cause among US children younger than 1 year is estimated at 31.2 per 1000. No data exist on respiratory syncytial virus (RSV)-specific hospitalization rates among high-risk Native Americans other than Alaska Natives, for whom the incidence of RSV hospitalization was estimated at 150 per 1000 among infants younger than 1 year. We aimed to estimate RSV hospitalization rates among Navajo and White Mountain Apache children younger than 2 years. METHODS: We conducted prospective population-level hospital-based surveillance to determine RSV hospitalization rates among Navajo and White Mountain Apache children younger than 2 years. From 1997 to 2000, all children who were admitted for acute lower respiratory tract infection between October 1 and March 31 had a nasopharyngeal aspirate obtained and tested for RSV by commercial enzyme immunoassay kits. We reviewed charts of children who tested positive for RSV antigen to determine disease severity. RESULTS: During 3 RSV seasons (1997-2000), 51.3% of 1837 admissions for acute lower respiratory tract infection among children younger than 2 years were attributed to RSV infection. The overall seasonal RSV hospitalization rate among children younger than 2 years was 63.6 per 1000 and 91.3 per 1000 among children younger than 1 year. In a univariate analysis, predictors of severity included age <6 months (relative risk: 6.8; 95% confidence interval: 3.1-17.0). CONCLUSIONS: Navajo and White Mountain Apache children are at high risk for RSV disease requiring hospitalization. A lower threshold for hospitalization or underlying chronic conditions that predispose to severe RSV disease do not seem to explain high RSV hospitalization rates in this population.

Hospitalization↗

PubMed2002

Trends in incidence and antimicrobial resistance of early-onset sepsis: population-based surveillance in San Francisco and Atlanta.

OBJECTIVE: Although increased use of intrapartum antibiotics caused significant declines in early-onset group B Streptococcus (GBS) infection, the effect on infections caused by other pathogens is not clear. The objective of this study was to determine trends in the incidence of early-onset sepsis caused by organisms other than group B streptococcus in the era of antimicrobial prophylaxis. METHODS: We conducted surveillance for early-onset sepsis as part of the Active Bacterial Core surveillance. A case was defined as isolation of bacteria from blood or cerebrospinal fluid from an infant who was 0 to 6 days of age and born in the surveillance area during 1998 through 2000 (248 184 births). RESULTS: We identified 408 cases of early-onset infection. GBS caused 166 (40.7%) cases (52 in 1998, 51 in 1999, and 63 in 2000 for incidences 0.62, 0.62, and 0.76 cases per 1000 live births, respectively). Other bacterial pathogens were identified in 242 cases (82 in 1998, 79 in 1999, and 81 in 2000 for incidences 0.99, 0.95, and 0.98 per 1000 live births, respectively) of early-onset sepsis. Escherichia coli caused 70 cases (0.25, 0.28, and 0.31 cases per 1000 live births, respectively, in 1998-2000). The proportion of E coli infections that were resistant to ampicillin increased significantly among preterm infants from 29% (2 of 7) in 1998 to 84% (16 of 18) in 2000 but not in full-term infants: 50% (4 of 8) in 1998 and 25% (1 of 4) in 2000. CONCLUSIONS: Whereas rates of early-onset sepsis caused by GBS and other pathogens were low and did not change significantly during the study period, antibiotic-resistant E coli infections among preterm infants increased. Overall, these trends are reassuring, but careful evaluation of the increase in resistant infections in very young infants is critical in the future.

Age of Onset↗