Search PubMed⌕ Search

Biomedical subjects

R Dagan

Publications and source records attributed to R Dagan.

At least 145 records · Page 8Linked to original sources

Respiratory carriage of Kingella kingae among healthy children.

The role of Kingella kingae as an invasive pathogen of young children is being increasingly recognized, but the niche of the organism in the respiratory tract and its prevalence in the normal flora of children remain unknown. To investigate these two aspects throat and nasopharyngeal cultures were obtained every 2 weeks from two cohorts of children, ages 6 to 42 months on enrollment, attending a day-care center in southern Israel. To determine the age-related prevalence of K. kingae, throat cultures were obtained from children ages 6 months to 14 years hospitalized for elective surgery who had not received antibiotics during the previous 30 days and from healthy infants younger than 6 months attending a well-baby-care clinic for routine vaccinations. During an 11-month follow-up 109 of 624 (27.5%) throat cultures but none of the nasopharyngeal cultures obtained from 48 day-care center attendees grew K. kingae. The monthly prevalence of K. kingae ranged from 6.1 to 34.6% with December and April peaks. Overall 35 of 48 (72.9%) children had at least one positive culture for the organism. Among the 27 children who had > or = 2 positive cultures, continuous and intermittent patterns of carriage were observed. None of the colonized children experienced an invasive K. kingae infection. The prevalence of pharyngeal carriage among surgical patients was 8.0%, and the organism was not isolated from any of the infants younger than 6 months attending the well-baby-care clinic.

Adolescent↗

Decay of maternally derived measles antibody in a highly vaccinated population in southern Israel.

The introduction of live attenuated measles vaccine in Israel during 1967 dramatically decreased the incidence of measles. However, cases still occur in periodic outbreaks and epidemics, with an increasing proportion of infants and children younger than 2 years of age. We examined the decay of maternally derived measles antibody during the first year of life in the Jewish population of Israel which represents a highly vaccinated population with immunization rates exceeding 90%. We used sera of healthy full term infants born in 1988 and 1989. Fifty specimens for each of the following age groups were used: 0 (cord blood), 2, 4, 6, 7 and 12 months. Three assays for each specimen were used: enzyme-linked immunosorbent assay (ELISA); hemagglutination-inhibition test (HI); and neutralization test (NT). Good correlation among all 3 tests was found. All cord blood specimens were positive by at least 2 assays. Seropositivity rates declined rapidly with age. Fifty percent of all 4-month-old infants and < 30% of all 6-month-old infants were positive by 1 test or more; at 12 months of age none of the tested specimens was positive by HI or NT and only 1 of 50 infants was positive by ELISA. In infants younger than 6 months of age, 5 (22%) of 23 specimens negative both by ELISA and by HI were positive by NT, but in 6-month-olds, only 2 (7%) of 28 negative by ELISA and HI were positive by NT, and in 12-month-olds none was positive. The results from southern Israel are similar to those obtained in North America and provide evidence that infants older than 6 months of age in a well-immunized population may be poorly protected against measles. On the basis of this information and epidemiologic data, the Israel Ministry of Health has recommended lowering the immunization age for measles, mumps and rubella from 15 months to 12 months.

Antibodies, Viral↗

Randomized comparison of meropenem with cefotaxime for treatment of bacterial meningitis. Meropenem Meningitis Study Group.

Broad-spectrum cephalosporins are drugs of choice for the treatment of meningitis in communities which can afford them. The emergence of cephalosporin-resistant pneumococci demands the clinical trial of alternate agents. Carbapenems are active against the bacteria causing meningitis, but the use of imipenem-cilastatin was frustrated by drug-associated seizures. The safety and efficacy of meropenem, a new carbapenem, were compared to those of cefotaxime in a prospective randomized trial of 190 children with bacterial meningitis. Seizures occurred within 24 h before antibiotic therapy in 16 of 98 patients (16%) randomized to receive meropenem and in 6 of 92 patients (7%) randomized to receive cefotaxime. In patients without seizures before therapy, seizures occurred during therapy in 5 of 82 patients (6%) receiving meropenem and in 1 of 86 patients (1%) receiving cefotaxime (95% confidence interval: -0.7%, 10.6%). None were thought to be drug related. Twenty-four meropenem-treated patients (24%) and 11 cefotaxime-treated patients (12%) had neurological abnormalities before therapy. In patients without pretherapy neurological abnormalities, these abnormalities were present after treatment in 4 of 74 meropenem-treated patients (5%) and in 2 of 81 cefotaxime-treated patients (2%) (95% confidence interval: -3.2%, 9.1%). Of 75 meropenem-treated and 64 cefotaxime-treated patients with pretherapy positive cerebrospinal-fluid cultures, 68 and 59, respectively, had repeat lumbar punctures. Bacterial eradication was found to be 100% in both groups. Our data suggest that meropenem may be a carbapenem agent that is well tolerated and effective in the treatment of bacterial meningitis.

Adolescent↗

Evaluation of novel vancomycin-containing medium for primary isolation of Kingella kingae from upper respiratory tract specimens.

A new selective medium (BAV), consisting of trypticase agar with 5% sheep hemoglobin and 2 micrograms of vancomycin per ml, was compared with the routine blood-agar medium for the primary isolation of Kingella kingae from upper respiratory specimens from a population of young children. Infection was detected by the BAV medium in 43 of 44 (98%) cultures positive for K. kingae, and detection of the organism was facilitated by inhibition of gram-positive flora. Infection was detected in only 10 of 44 (23%) positive cultures by the blood-agar medium, and plates were usually covered by abundant normal flora, making the recognition of K. kingae much more difficult. Challenge of the medium with different organisms of respiratory origin showed that the BAV medium was inhibitory for gram-positive cocci and Haemophilus influenzae but that it supported growth of eight K. kingae strains isolated from patients with invasive infections. The new medium appears to be a useful epidemiological tool for studying the respiratory carriage of K. kingae.

Bacteriological Techniques↗

Fluoroquinolones in paediatrics--1995.

The fluoroquinolones are characterised by a broad spectrum of antibacterial activity that includes many Mycobacterium, Chlamydia, Legionella, and Mycoplasma species as well as many multiply-resistant bacterial strains, good oral bioavailability, extensive tissue penetration, low protein binding and long elimination half-lives. Numerous clinical trials have shown that these compounds are effective and well tolerated in the treatment of adult patients with various infections, including urinary tract, respiratory tract, skin and soft tissue, bone and joint, and gynaecological infections, sexually transmitted diseases, infectious diarrhoea, infections in immunocompromised patients, and in surgical prophylaxis. Thus, there is increasing pressure to use this class of drugs in paediatric patients. However, concerns regarding adverse effects, particularly cartilage toxicity, have restricted development of the fluoroquinolone compounds for use in this population. Potential indications include Pseudomonas infections (mainly exacerbations of cystic fibrosis), urinary tract, gastrointestinal and central nervous system infections, infections in immunocompromised patients, certain otorhinolaryngological infections and infections caused by multiply-resistant pathogens. To date, clinical experience gained with fluoroquinolones in paediatric infections, which has been mainly on a compassionate-use basis, indicates that well-designed formal studies should be conducted to fully assess the efficacy and tolerability of these agents in specific indications in children.

Adolescent↗

Evaluation of an enzyme immunoassay for the detection of Cryptosporidium spp. in stool specimens from infants and young children in field studies.

Diagnosis of Cryptosporidium is made by the identification of oocysts in stool specimens. Screening in field studies relies mainly on acid-fast staining followed by microscopic examination. The more sensitive immunofluorescent antibody (IFA) staining method is time-consuming, may involve technical difficulties, and is extremely costly as a screening procedure in field studies. We evaluated the diagnostic utility of a commercially available enzyme immunoassay (EIA), which detects Cryptosporidium-specific antigen, in 204 unprocessed stool specimens obtained from patients less than three years of age from a field study in southern Israel. When compared with the routine screening procedure applied in this field study (screening by acid-fast staining and microscopy after concentration, and confirmation of positive results by IFA), both the sensitivity and specificity were 98%. Of 139 specimens negative by microscopy, 13 (9.3%) were positive by the EIA. Eleven of these were confirmed by inhibition with antibody to Cryptosporidia-specific antigen. The EIA is an important tool for identifying Cryptosporidium in fecal specimens in field studies since it is sensitive, specific, simple to use, and unaffected by the presence of a preservative.

Animals↗

Carbapenem treatment of meningitis.

The carbapenem class of antibacterial agents is highly effective in vitro against the bacterial pathogens causing meningitis. Both imipenem and meropenem penetrate into the cerebrospinal fluid of children with inflamed meninges in the acute phase of meningitis. The wider clinical use of imipenem/cilastatin for the treatment of meningitis has been limited by the high incidence of seizures (up to 33%) in patients not having seizures prior to drug therapy. However, imipenem/cilastatin has been successfully used for the treatment of pneumococcal meningitis following failure of treatment with third-generation cephalosporins. The bacteriological and clinical efficacy of meropenem appears similar to that of cefotaxime in the management of meningitis in children and there was no significant propensity of either meropenem or cefotaxime to cause seizures. Meropenem has also been usefully employed to treat multi-resistant Pseudomonas aeruginosa meningitis. These data suggest that meropenem should be further investigated for use in the treatment of meningitis.

Animals↗

Potential interventions for the prevention of childhood pneumonia: geographic and temporal differences in serotype and serogroup distribution of sterile site pneumococcal isolates from children--implications for vaccine strategies.

Streptococcus pneumoniae is a leading cause of fatal bacterial pneumonia in young children. Pneumococcal polysaccharide vaccines have not been promoted for use in young children because many constituent serotypes are not immunogenic in children < 2 years old. Conjugating pneumococcal polysaccharide epitopes to a protein carrier would likely increase vaccine immunogenicity in children. We reviewed published and unpublished pneumococcal serotype and serogroup data from 16 countries on 6 continents to determine geographic and temporal differences in serotype and serogroup distribution of sterile site pneumococcal isolates among children and to estimate coverage of proposed and potential pneumococcal conjugate vaccine formulas. The most common pneumococcal serotypes or groups from developed countries were, in descending order, 14, 6, 19, 18, 9, 23, 7, 4, 1 and 15. In developing countries the order was 6, 14, 8, 5, 1, 19, 9, 23, 18, 15 and 7. Development of customized heptavalent vaccine formulas, one for use in all developed countries and one for use in all developing countries, would not provide substantially better coverage against invasive pneumococcal disease than two currently proposed heptavalent formulas. An optimal nanovalent vaccine for global use would include serotypes 1, 5, 6B, 7F, 9V, 14, 18C, 19F and 23F. Geographic and temporal variation in pneumococcal serotypes demonstrates the need for a species-wide pneumococcal vaccine.

Age Distribution↗

Epidemiology of Shigella infections in two ethnic groups in a geographic region in southern Israel.

The epidemiology of shigellosis in the Jewish and Bedouin populations that coexist in the same geographic region in southern Israel and share the same medical facilities but live separately under different socioeconomic conditions was examined in a retrospective, culture-based study. The average annual attack rate for the four-year period 1989-1992 was 368/100,000 inhabitants. The average annual attack rate among the Jews, who enjoy Western socioeconomic conditions, was 413/100,000 and the disease showed summer and winter peaks. Shigella sonnei caused 3,336 of 4,560 (73.2%) attacks in this group, and the attack rate of Shigella flexneri decreased during the study period. Among the Bedouins, many of whom live in poverty and overcrowding, a single annual summer peak was observed, the average annual attack rate being 197/100,000 and Shigella flexneri caused 389 of 583 episodes (66.7%). Resistance to ampicillin or tetracycline was noted in 57% of all Shigella isolates, and 82% were resistant to cotrimoxazole. It is concluded that shigellosis is highly endemic in southern Israel, resistance to antimicrobial drugs is common and living conditions of the population influence the seasonal occurrence of the disease and select for morbidity with specific organisms.

Anti-Bacterial Agents↗

Acquisition of immunity in mothers of infants administered trivalent oral poliovirus vaccine.

The hypothesis that live oral poliovirus vaccine (OPV) confers immunity to persons in close contact with the vaccine recipient was tested by comparing cord blood antibody titers in 31 first-born neonates to those of 48 neonates with one or more siblings adequately immunized with OPV. A borderline or negative result (defined as a reciprocal titer of < or = 8) for at least one type was significantly more prevalent among first-born neonates than among neonates with one or more siblings [17/31 (55%) versus 17/48 (27%) respectively; p < 0.03]. This difference was consistent for all three poliovirus types. The geometric mean titer (GMT) was consistently higher for each serotype in infants with one or more siblings compared with first-born neonates: 134.9 versus 64.5 for poliovirus 1; 262.1 versus 95.6 for poliovirus 2; and 48.6 versus 19.4 for poliovirus 3, respectively. When cord blood of neonates with two or more siblings was compared to that of neonates with only one sibling, no difference in titers was observed. Since mothers of one or more infants were on average older and less educated, the results were adjusted accordingly, but the same trend was observed again. These findings support the notion that OPV is important, not only as a vaccine for the individual infants, but also as a means of conferring immunity to persons in close contact.

Adult↗

Detection of Cryptosporidium and Giardia intestinalis in Bedouin children from southern Israel.

During an 18 month period, a total of 4796 stool specimens collected from 151 Bedouin children enrolled in a cohort study and followed from birth, were screened for Giardia intestinalis, Cryptosporidium spp. and other intestinal parasites. Specimens were collected in phenol-alcohol-formalin (PAF) preservative and examined prior to, and after, formalin-ether concentration (FEC). During 6 months of the second year Giardia intestinalis was observed in 17.6% of the specimens and Cryptosporidium in 0.9% as compared with 1.8% (Giardia intestinalis) and 1.6% (Cryptosporidium) observed during the first year. Giardia intestinalis was detected in 8.4% (407/4796) of all the samples examined and Cryptosporidium in 1.3% (63/4796). Other intestinal protozoan parasites and helminthic ova demonstrated in the stool specimens included: Entamoeba coli (0.1%); Entamoeba histolytica (< 0.1%); Hymenolepis nana (0.1%); and Trichuris trichiura (< 0.1%). Mixed infection with 2 parasites was observed in 0.3% of the specimens. PAF fixation was found to be highly effective in preserving the integrity and antigenicity of both Cryptosporidium-oocysts and Giardia intestinalis-cysts. The detection rate of Giardia intestinalis and Cryptosporidium before FEC was not significantly different from that obtained after FEC, showing differences of only 1% and 3% for Giardia intestinalis and Cryptosporidium, respectively.

Animals↗

Sex differences in the humoral antibody response to live measles vaccine in young adults.

BACKGROUND: Following vaccination of children using high-titre live measles vaccine, excess non-specific mortality was reported, particularly among females. Since vaccination with live measles virus results in a temporary depression of the immune response to other antigens, the female predominance in subsequent non-measles mortality may be due to sex differences in response to live measles vaccines. METHODS: In this study, the immunogenicity of standard titre live Schwarz strain measles vaccine was examined 2 and 4 weeks post-vaccination in 223 males and 66 female aged 18-20 years in Israel in 1991. RESULTS: Females had higher post-vaccination geometric mean titre (GMT) at all levels of pre-vaccination titres at both 2 and 4 weeks. Furthermore, after controlling for differences in pre-vaccination titres, overall the post-vaccination GMT for females was about 50% higher than for males (P < 0.001). CONCLUSIONS: These findings indicate that females exhibit a stronger humoral immune response to measles vaccine. Possible sex differences in immunosuppression following measles vaccination should be explored.

Adolescent↗

Epidemiology of pediatric meningitis caused by Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis in Israel: a 3-year nationwide prospective study. Israeli Pediatric Bacteremia and Meningitis Group.

In a 3-year nationwide prospective study on pediatric meningitis caused by Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis in Israel, 1258 invasive infections with a known focus were observed. Meningitis was found in 482 (38%): 56%, 16%, and 76% of all infections by H. influenzae type b, S. pneumoniae, and N. meningitidis, respectively. The incidence of meningitis during the first year of life was 67.1, 17.5, and 9.5/100,000 for H. influenzae type b, S. pneumoniae, and N. meningitidis, respectively, and in children < 5 years old it was 18.5, 5.3, and 5.2. Extrapolated for a population in which 100,000 live births occur yearly, 2097 hospital days were required. The case fatality rate was 2.2%, 5.9%, and 6.3% for H. influenzae type b, S. pneumoniae, and N. meningitidis, respectively. Boys were affected significantly more often than girls, but mortality was higher among girls. On the basis of the observed serotypes and age distribution, even with optimal vaccine development in the next 5 years, it is not likely that > 50% of all cases will be prevented.

Age Distribution↗