Biomedical subjects

R Dagan

Publications and source records attributed to R Dagan.

At least 91 records · Page 5Linked to original sources

PubMed1998

Detection of enterotoxigenic Escherichia coli in stool specimens by polymerase chain reaction.

A polymerase chain reaction (PCR) protocol for rapid (7 h) detection of enterotoxigenic Escherichia coli (ETEC) is described. This protocol has been validated on 57 stool samples from young children by comparing it with the colony hybridization technique. A good agreement was found between the two methods with Cohen's kappa statistics of 0.87 and 0.79 for the detection of the heat-stable toxin (ST) and heat-labile toxin (LT), respectively. Of 26 samples positive for LT and 15 samples positive for ST by colony hybridization, 21 (81%) and 15 (100%) were also found to be positive for LT and ST by PCR, respectively. Only one sample identified as LT-negative by colony hybridization was found to be positive by PCR. However, 3 of 42 samples of ST-negative by colony hybridization were detected as positive by PCR. A reconstruction experiment revealed that PCR could detect LT-producing and ST-producing ETEC at minimal concentrations of 2.5 x 10(3) cfu and 2.5 x 10(2) cfu per gram of feces, respectively. These data indicate the possible use of this method for rapid identification of ETEC-associated diarrhea in clinical and epidemiological settings.

Bacterial Toxins↗

PubMed1998

Hospitalizations for infectious diseases in Jewish and Bedouin children in southern Israel.

Two different population groups reside in the Negev region of southern Israel and have equal, and free from financial barrier, access to tertiary care at a single regional hospital. The Jewish population has a largely urban and industrialized lifestyle, while the Moslem Bedouins are in transition from their traditional nomadic life to settlement. To examine the differences in morbidity patterns reflected in hospitalizations, the computerized hospitalization records of children <15 years of age, for 1989-1991 were used (n=15,947). Rates of hospitalizations for infectious diseases were significantly higher for Bedouins in comparison to Jews (250 and 121/10,000 child years, respectively, odds ratio (OR): 2.1, 95% confidence interval (CI): 2.0-2.2, p < 0.001). Rates of hospitalization per 10,000 child years in Bedouins and Jews for diarrhea were 114 and 32 (OR: 3.7, 95% CI: 3.3-4.0, p < 0.001), respectively, and for pneumonia 55 and 19 (OR: 2.9, 95% CI: 2.6-3.3, p < 0.001), respectively. In infants the differences were even more pronounced, especially for diarrheal diseases. In Bedouin children infectious diseases were associated with longer hospital stay, more pediatric Intensive Care hospitalizations (OR: 2.7, 95% CI: 1.7-4.5,p < 0.001), and higher in-hospital mortality (OR: 5.7, 95% CI: 2.8-12.2, p < 0.001). Thus, Bedouin children are at higher risks of hospitalizations for infectious diseases in early childhood, as compared to Jewish children. This may reflect the differences in lifestyle, environmental and social conditions of the two populations.

Adolescent↗

PubMed1998

Reply

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Journal Article↗

PubMed1998

Person-to-person transmission of Kingella kingae among day care center attendees.

Fifty Kingella kingae organisms, isolated from tonsillar cultures of day care center attendees during an 11-month period, and 60 isolates derived from epidemiologically unrelated individuals, including 19 isolates from respiratory carriers and 41 isolates from patients with invasive infections, were typed by immunoblotting, pulsed-field gel electrophoresis, and ribotyping. One strain, defined by unique immunoblotting, pulsed-field gel electrophoresis, and ribotyping patterns, represented 14 day care isolates (28%) and was frequently isolated during the first half of the follow-up period; a second strain represented 23 (46%) isolates and prevailed during the last 5 months. Children frequently carried the same strain continuously or intermittently for weeks or months, when it was replaced by a new strain. Epidemiologically unrelated organisms showed greater variability, and no strain represented >5% of isolates. The present results support person-to-person transmission of K. kingae among young children in the day care setting.

Carrier State↗

PubMed1998

Acquisition, carriage, and transmission of pneumococci with decreased antibiotic susceptibility in young children attending a day care facility in southern Israel.

The prevalence and transmission of antimicrobial drug-resistant pneumococci was studied in 48 children attending a day care facility in southern Israel. Nasopharyngeal cultures were obtained every 2 weeks for 10 months, and antibiotic susceptibility of isolates was determined by disk diffusion and E-test. Relatedness of isolates was investigated by capsular typing, ribotyping, and arbitrarily primed polymerase chain reaction. Pneumococci were recovered during 362 (63%) of 573 fortnights, and 219 (60%) of these isolates showed decreased susceptibility to at least one drug; 154 (43%) were intermediately susceptible to penicillin and 51 (14%) were multiresistant. Combining the different typing methods showed that a limited number of clones circulated in the facility. Clones exhibiting decreased antibiotic susceptibility (especially 23F, intermediately susceptible to penicillin and resistant to trimethoprim-sulfamethoxazole, and multiresistant 6B) were more frequently isolated and persisted longer than did fully susceptible clones. By multivariate analysis, carriage of organisms with decreased antibiotic susceptibility was associated with young age, female sex, winter season, and exposure to antimicrobial drugs during the previous month.

Age Factors↗

PubMed1998

Persistent diarrhea in a cohort of Israeli Bedouin infants: role of enteric pathogens and family and environmental factors.

This study examined the role of enteric pathogens and infant, family, and household characteristics in persistent diarrhea. Bedouin infants from southern Israel were followed from birth to age 18-23 months. During monthly home visits, stool samples were obtained, and feeding practices and history of diarrhea were determined, and at age 3 months, an environmental assessment was done. Diarrhea surveillance was either via a network covering all community health care facilities or via weekly interviews with the mother. None of the enteric pathogens examined, including Cryptosporidium parvum and enteroaggregative Escherichia coli, were associated with persistent diarrhea. In multivariate analyses, age at first diarrheal illness and maternal age and maternal education were independently and significantly associated with the risk of persistent diarrhea. These data suggest that persistent diarrhea is a clinical entity that may be related less to a specific enteric pathogen and more to the health experiences of children and their home environment.

Animals↗

PubMed1998

High prevalence of "Simkania Z," a novel Chlamydia-like bacterium, in infants with acute bronchiolitis.

The newly described microorganism "Simkania Z" ("Z"), an obligate intracellular, penicillin-resistant microorganism most closely related to the chlamydiae, has been associated with adult community-acquired pneumonia. The possible involvement of "Z" in bronchiolitis in infants was examined in a prospective study of 239 infants with bronchiolitis and 78 controls. Other potential etiologic agents sought were respiratory syncytial virus (RSV), adenovirus, and cytomegalovirus. Evidence for the presence of "Z" in nasopharyngeal wash specimens (polymerase chain reaction and/or culture) was found in 25% of infants with bronchiolitis, while controls were all negative (P < .001). A serum IgA response to "Z" infection was detected by immunoperoxidase assay in 15% of infants with bronchiolitis versus 1.3% of controls (P < .001). Clinical findings were not different for infants with bronchiolitis associated with RSV alone, "Z" alone, or RSV and "Z" together. The high prevalence of "Z" in infants with bronchiolitis, often accompanied by an immune response, suggests a possible etiologic role of this agent in the disease.

Adenoviruses, Human↗

PubMed1998

Resistance pattern of middle ear fluid isolates in acute otitis media recently treated with antibiotics.

BACKGROUND: Little information is available about the effect of antibiotic treatment on the prevalence and MIC of the subsequently isolated pathogens in cases of acute otitis media (AOM) failing a course of antibiotic therapy. This information is important, particularly regarding the effectiveness of the oral antibiotics used in children failing initial therapy. PATIENTS AND METHODS: One hundred eighty-one children with culture-positive AOM were prospectively studied between October, 1995, and July, 1996. Sixty-three (35%) patients received various antibiotics for variable periods during the 14 days preceding enrollment. RESULTS: A total of 94 Streptococcus pneumoniae (Pnc) and 113 Haemophilus influenzae (Hi) were isolated. Thirty-eight Pnc and 35 Hi were isolated in the 63 patients with recently treated AOM. Pnc as a single isolate was more prevalent in patients recently treated with antibiotics (27 of 63, 43%) than among those not recently treated (32 of 118, 27%, P = 0.047). The MIC50 values of penicillin, cefaclor and cefuroxime axetil for Pnc were significantly higher in the pneumococci isolated from patients recently treated than among those isolated from patients not recently treated with antibiotics (0.38, 3 and 0.75 microg/ml vs. 0.094, 0.38 and 0.12 microg/ml, respectively). Seventy-nine percent of Pnc isolates in the recently treated group had MIC for penicillin of >0.1 microg/ml vs. only 47% in those not recently treated (P < 0.05). The respective figures for MIC >0.5 microg/ml of cefaclor were 79% vs. 41% for the recently treated and not recently treated groups (P < 0.001); cefuroxime MIC >0.5 microg/ml was found in 61 and 25%, respectively (P = 0.001). CONCLUSIONS: Pneumococcus is more prevalent in AOM after a recent antibiotic treatment, and the MIC of the commonly used beta-lactam drugs for Pnc is considerably higher in this setting. In view of our data, the use of oral cephalosporins like cefaclor or cefuroxime as second line drugs in the treatment of unresponsive AOM, particularly in regions where resistant PNC is prevalent, should be reconsidered.

Acute Disease↗

PubMed1998

Prevalence of intestinal infections caused by diarrheagenic Escherichia coli in Bedouin infants and young children in Southern Israel.

OBJECTIVE: To evaluate the prevalence of different Escherichia coli categories in symptomatic and asymptomatic infants and children residing in a Bedouin township in Southern Israel. METHODS: A total of 1613 stool samples were collected from a cohort of 234 infants and young children followed from birth up to 2 years of age. E. coli colonies from stool cultures from children during a diarrhea episode and those from nondiarrhea stools were hybridized with DNA probes specific for enteropathogenic, enteroinvasive, enterotoxigenic (ETEC), enteroaggregative, diffuse adherent and enterohemorrhagic strains. RESULTS: There were 1469 of 1613 (91%) samples positive for E. coli. The prevalence of E. coli categories was: enteroaggregative (25.9%); diffuse adherent (21.8%), ETEC (12.9%); enteropathogenic (7.3%); enterohemorrhagic (0.5%); and enteroinvasive (0.2%). ETEC, expressing the heat-stable enterotoxin (ST), was the only category isolated significantly more often from cases than from controls (P = 0.005). Of the two heat-stable enterotoxins screened in this study, only ETEC-heat stable enterotoxin (STh), the form isolated from human pathogenic ETEC, could be associated with diarrhea, whereas ETEC-STp, produced by ETEC of porcine origin, was not related to diarrhea. ETEC infections peaked during the warm, dry season. Prolonged shedding of E. coli postdiarrhea was not found in this population. CONCLUSION: The present cohort study confirmed that in this semiurban area, highly endemic for diarrheal disease, ETEC is an important cause of diarrhea in children.

Arabs↗

PubMed1998

Early eradication of pathogens from middle ear fluid during antibiotic treatment of acute otitis media is associated with improved clinical outcome.

OBJECTIVE: To determine the relation between early bacteriologic eradication and clinical outcome of acute otitis media (AOM) in infants and young children treated with various antibiotics. STUDY DESIGN: The study group consisted of patients ages 3 to 24 months seen at the Pediatric Emergency Room with: (1) symptoms and physical findings consistent with AOM of < or = 7 days duration; (2) no spontaneous perforation or tympanostomy tubes; (3) positive initial middle ear fluid culture; and (4) a follow-up to at least Day 10+/-2 of the study with a second culture performed 72 to 96 h after initiation of antibiotic treatment. Any patient with a positive middle ear fluid culture 72 to 96 h after initiation of antibiotic treatment was considered to have bacteriologic failure. Otologic evaluation was done by an otolaryngologist unaware of the culture results and of the study drug allocation. A clinical score based on body temperature, report of irritability and ear tugging observed by the parents and the appearance and redness of the ear drum as observed by the otolaryngologist was also used for clinical evaluation. RESULTS: The study group consisted of 123 patients, of whom 57 (46%) had positive middle ear fluid 72 to 96 h after initiation of antibiotic treatment. Clinical failure was observed in 21 of 57 (37%) patients in whom bacteriologic eradication did not occur vs. only 2 of 66 (3%) patients with bacteriologic eradication after 3 to 4 days of treatment (P < 0.001). Clinical score for both moderate and severe disease decreased significantly faster in those with bacteriologic eradication than in those in whom middle ear fluid was still culture-positive 72 to 96 h after initiation of treatment. CONCLUSION: Clinical failures in our population were associated with inability to eradicate the causative organisms of AOM from the middle ear fluid within 3 to 4 days after initiation of antibiotic therapy. Most patients (including those without bacteriologic eradication) improved after 3 to 4 days of treatment, but patients with sterile middle ear fluid felt better after 3 to 4 days of treatment than patients in whom middle ear fluid was still culture-positive.

Acute Disease↗

PubMed1998

A nationwide prospective surveillance study in Israel to document pediatric invasive infections, with an emphasis on Haemophilus influenzae type b infections. Israeli Pediatric Bacteremia and Meningitis Group.

BACKGROUND AND METHODS: An ongoing nationwide prospective surveillance study was initiated in Israel in October, 1988, to document childhood invasive infections caused by Haemophilus influenzae type b (Hib), Streptococcus pneumoniae and Neisseria meningitidis. This study enabled us to document the effect on childhood invasive Hib disease of the introduction of conjugate Hib vaccines to Israel. RESULTS: The incidence of invasive Hib disease before the age of 5 years dropped from 34 per 100000 before initiation of immunization to < 5 per 100000 in 1995 and is projected to be <4 in 1996. After <2 years, when various conjugate vaccines had been available in the private sector alone and had achieved partial coverage only, the Israeli Ministry of Health decided to add Hib conjugate vaccine to the regular infant immunization program, free of charge, effective for all infants born after January 1, 1994. The vaccine chosen was Hib polysaccharide linked to outer membrane protein complex of N. meningitidis B. Vaccine coverage has exceeded 90% of all infants born since January 1, 1994. Efficacy and effectiveness during the first 34 months of the program (January 1, 1994, to October 31, 1996) were 95.4 and 99.7%, respectively, for all invasive Hib disease and 97 and 99.4%, respectively, for Hib meningitis. CONCLUSION: The described ongoing surveillance program showed the existence and extent of Hib problems in Israel and documented the success of the immunization program in essentially eliminating the disease in Israel.

Child, Preschool↗

PubMed1998

Dynamics of pneumococcal nasopharyngeal colonization during the first days of antibiotic treatment in pediatric patients.

BACKGROUND: Nasopharyngeal (NP) carriage of antibiotic-resistant Streptococcus pneumoniae was shown to be associated with recent antibiotic treatment. To date no studies have evaluated early dynamics of pneumococcal NP carriage during antibiotic treatment. OBJECTIVES: To observe changes in NP pneumococcal carriage within 3 to 4 days after initiation of antibiotic treatment in acute otitis media (AOM). METHODS: Patients ages 3 to 36 months with AOM treated with various antibiotics were prospectively followed. Nasopharyngeal culture for S. pneumoniae was obtained before (Day 1) and 72 to 96 h after initiation of treatment (Days 4 to 5). Antibiogram and serotyping were performed in all isolates as was also the MIC of penicillin. The disappearance and persistence of the initial isolates as well as the appearance of isolates with new serotype or with new antibiotic susceptibility patterns were investigated. RESULTS: A total of 120 patients were studied: 106 received beta-lactam antibiotics and 14 received azithromycin. Among the initial 76 pneumococcal isolates 63, 37 and 13% were resistant to > or =1, > or =2 and > or =3 antibiotic drugs. After 3 to 4 days of treatment with various beta-lactam drugs, 45, 63 and 100% of isolates with MIC values of <0.1 microg/ml, 0.125 to 0.25 microg/ml and 0.38 to 1.0 microg/ml, respectively, persisted in the NP (P = 0.038). There was a difference between the various beta-lactam drugs in their effect on NP colonization: a drug with lower MIC values (cefuroxime-axetil) had a better eradication rate of penicillin-susceptible organisms than a less active one (cefaclor), but neither significantly reduced carriage of penicillin nonsusceptible isolates. Azithromycin eliminated carriage of macrolide-susceptible organisms but increased the carriage of macrolide-resistant ones. In 19 of 120 (16%) patients a new S. pneumoniae isolate was recovered 3 to 4 days after initiation of treatment. Of those 16 (84%) were resistant to the drug the patient was receiving. CONCLUSION: A rapid selection of nonsusceptible NP pneumococcal isolates during antibiotic treatment for AOM is common. This phenomenon may contribute to the spread of resistant pneumococci.

Acute Disease↗

PubMed1998

Bacteriologic efficacy of a three-day intramuscular ceftriaxone regimen in nonresponsive acute otitis media.

OBJECTIVE: To determine the bacteriologic efficacy of ceftriaxone in nonresponsive acute otitis media in children. METHODS: In a prospective study 92 patients ages 3 to 36 months (median, 11 months) with culture-proved nonresponsive acute otitis media were studied from January, 1995, through August, 1997. The patients were treated with intramuscular ceftriaxone (50 mg/kg/l/day) for 3 days. Middle ear fluid was aspirated for culture by tympanocentesis on day of enrollment (Day 1); a second tap was performed on Days 4 to 10. Additional middle ear fluid cultures were obtained if clinical relapse occurred. Bacteriologic failure was defined by positive culture on Days 4 to 10. Patients were followed until Day 17+/-2. Susceptibility was measured by E test. RESULTS: The main drugs administered before enrollment were amoxicillin (38%), amoxicillinclavulanate (25%) and cefaclor (20%). Organisms recovered (n=105) were: Haemophilus influenzae, 54; Streptococcus pneumoniae, 47; Moraxella catarrhalis, 2; and Streptococcus pyogenes, 2. Thirty-four (72%) of the 47 S. pneumoniae isolates were intermediately resistant to penicillin (MIC 0.1 to 1.0 microg/ml), but all were susceptible to ceftriaxone (MIC < 0.5 microg/ml). Bacteriologic eradication was achieved in 100 of 105 (95%) cases: 54 of 54 (10O%) H. influenzae, 43 of 47 (92%) S. pneumoniae, 1 of 2 (50%) M. catarrhalis and 2 of 2 (100%) S. pyogenes. Bacteriologic success (with no relapse) occurred in 13 of 13 (100%) penicillin-susceptible S. pneumoniae vs. 28 of 34 (82%) S. pneumoniae intermediately resistant to penicillin (4 cases of bacteriologic failure and 2 cases of relapse). CONCLUSION: A 3-day intramuscular ceftriaxone regimen is efficacious for the treatment of nonresponsive acute otitis media. The optimal duration of treatment in cases of nonresponsive acute otitis media and whether ceftriaxone is efficacious for the treatment of nonresponsive otitis media caused by S. pneumoniae highly resistant to penicillin is yet to be determined.

Acute Disease↗

PubMed1998

Prevalence of antimicrobial-resistant pathogens in middle ear fluid: multinational study of 917 children with acute otitis media.

The management of acute otitis media is complicated by the emergence of resistance to beta-lactam and other antibiotics among common pathogens. We conducted a large, international study of infants and children with acute otitis media to identify pathogens and susceptibility patterns. During the winter of 1994 to 1995, middle ear fluid samples were collected from 917 patients with acute otitis media in Bulgaria, the Czech Republic, Hungary, Romania, Slovakia, Israel, and the United States. A single reference laboratory performed in vitro susceptibility testing. Pathogens were isolated from 62% of the patients. For Streptococcus pneumoniae (30% of the patients), untypeable Haemophilus influenzae (17%), and Moraxella catarrhalis (4%), there was significant variation among geographic regions (P < 0.001). The composite susceptibilities of these three organisms to amoxicillin ranged from 62% in the United States to 89% in Eastern and Central Europe; the corresponding susceptibilities to amoxicillin-clavulanate ranged from 90% in Israel to 95% in Eastern and Central Europe. beta-Lactamase was produced by 31 and 100% of the isolates of H. influenzae and M. catarrhalis, respectively. More isolates of S. pneumoniae were susceptible to amoxicillin (90%) or amoxicillin-clavulanate (90%) than to penicillin (70%; P = 0.002). The prevalence of resistant S. pneumoniae was highest in patients less than 12 months of age. S. pneumoniae, H. influenzae, and M. catarrhalis remain the most important bacterial pathogens in patients with acute otitis media; however, their prevalence is variable and resistance patterns are changing.

Acute Disease↗

PubMed1998

Reduced response to multiple vaccines sharing common protein epitopes that are administered simultaneously to infants.

The plethora of newly discovered vaccines implies that, in the future, many vaccines will have to be administered simultaneously to infants. We examined the potential interference with the immune response of several coadministered vaccines containing the same protein component, namely, tetanus toxoid (TT). Infants simultaneously receiving a tetravalent pneumococcal vaccine conjugated to TT (PncT) and a diphtheria-tetanus-pertussis-poliovirus-Haemophilus influenzae type b-tetanus conjugate vaccine showed significantly lower anti-H. influenzae type b polysaccharide (polyribosylribitol phosphate [PRP]) antibody concentrations than those receiving either a tetravalent pneumococcal vaccine conjugated to diphtheria toxoid or placebo. A dose range study showed that anti-PRP antibody concentrations were inversely related to the TT content of the PncT vaccines administered in infancy. Postimmunization antitetanus antibody concentrations were also affected adversely as the TT content of the coadministered vaccines was increased. This phenomenon, which we believe derives from interference by a common protein carrier, should be taken into account when the introduction of an immunization program including multiple conjugate vaccines is considered.

Antibodies, Bacterial↗

PubMed1998

Prospective study to determine clinical relevance of detection of pneumococcal DNA in sera of children by PCR.

We undertook a prospective study to evaluate the accuracy of PCR of serum (aimed at the pneumococcal pneumolysin gene) at detecting pneumococcal infections in infants and children. The assay was positive for all blood and cerebrospinal fluid culture-positive samples and for 38 and 44% of patients with lobar pneumonia and acute otitis media, respectively. It was positive for 17% of healthy controls. There was a marked effect of age on the rate of positivity among healthy controls, with the highest rate (33%) being in 2-year-old children, the age group with the highest rate of nasopharyngeal (NP) carriage; the lowest rate was found among infants <2 months of age (13%) and adults ages 18 to 50 years (0%), age groups with the lowest NP pneumococcal carriage rates. Carriers of pneumococci in the nasopharynges had a higher rate of positivity than noncarriers of pneumococci in the nasopharynges for all groups. Our results suggest that although PCR of serum is a sensitive test for the detection of Streptococcus pneumoniae in sterile fluids, its high rate of positivity for healthy controls, related to NP pneumococcal carriage, might exclude it from being useful in detecting deep-seated pneumococcal infections.

Adolescent↗

PubMed1998

Treatment failures in otitis media--what can we learn?

The role of antibiotics in acute otitis media is to eradicate the causative pathogen from the middle ear. It is therefore important to have antibiotics with good activity which reach the organism in an appropriate concentration at the infection site. Without these parameters successful treatment will not be achieved. The ultimate test of this concept is to demonstrate the eradication of a pathogen from middle ear aspirate post-treatment. Careful analysis of treatment failures show that increasing rate of resistance to existing drugs is associated with a decreased rate of pathogen eradication in acute otitis media and there is a clear correlation between bacteriologic failure and clinical failure.

Acute Disease↗

PubMed1998

[Epidemiology of invasive Hemophilus influenzae B infections in Bedouins and Jews; conjugate Hib vaccines].

From 1989 to 1996, 139 cases of invasive Hemophilus influenzae B (Hib) infections were identified in children in the Negev, 110 of which occurred before introduction of the conjugate vaccine (1989-92). At that time there were 60.5 cases of Hib per 100,000 in the Negev among children under 5 years of age. During 1995-1996, when Hib conjugate vaccine was part of the regular immunization program, Hib decreased to 6.5 cases per 100,000 in that age group. The effectiveness of PRP-OMP vaccine was 96.5% among Jews and 89% among Bedouins, and the efficacy of the immunization program was 99.99%. This degree of success exceeded all expectations based on the literature. During the whole study period, Hib infections were more frequent among Bedouins than Jews. There was no significant difference in the occurrence of Hib among Jews in the Negev before and after the vaccine was introduced. Hib among Bedouins in the Negev was significantly more frequent than in the Israeli population as a whole before the vaccine was introduced. That gap narrowed after the vaccine was introduced because of the decrease in morbidity among the 2 groups.

Arabs↗