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Ron Dagan

Publications and source records attributed to Ron Dagan.

At least 37 records · Page 2Linked to original sources
PubMed2005

Serum serotype-specific pneumococcal anticapsular immunoglobulin g concentrations after immunization with a 9-valent conjugate pneumococcal vaccine correlate with nasopharyngeal acquisition of pneumococcus.

BACKGROUND: Immunization with pneumococcal conjugate vaccines (PCVs) reduces nasopharyngeal colonization by Streptococcus pneumoniae. We attempted to correlate postvaccination serum serotype-specific pneumococcal anticapsular immunoglobulin (Ig) G concentrations with new acquisitions of vaccine-type (VT) serotypes and the VT-related serotype 6A. METHODS: A total of 132 day care center attendees aged 12-35 months received a 9-valent PCV (PnCRM9) and were followed for 2 years for new nasopharyngeal acquisitions of S. pneumoniae. A total of 132 control subjects received a meningococcus type C conjugate vaccine. Serum serotype-specific pneumococcal anticapsular IgG concentrations were determined at 1 month after complete immunization. RESULTS: A logistic regression model of the probability of having a new acquisition of S. pneumoniae (for serotypes 9V, 14, 19F, and 23F) as a function of the IgG concentration showed a negative coefficient, indicating that higher IgG concentrations led to a decreasing probability of having a new acquisition, and achieved statistical significance for serotypes 14 and 19F. Similarly, a new acquisition of serotype 6A was shown to be significantly inversely related to the anti-6B IgG concentration. An effect of the IgG concentration on duration of carriage was not demonstrated. CONCLUSION: The magnitude of herd protection against S. pneumoniae provided by a PCV may depend on the magnitude of IgG concentrations.

Antibodies, Bacterial↗
PubMed2005

Acute otitis media caused by Streptococcus pyogenes in children.

BACKGROUND: Streptococcus pyogenes, or group A beta -hemolytic Streptococcus (GAS), is an important causative agent of bacterial pharyngotonsillititis and skin, soft-tissue, and invasive infections. Although it is also an important pathogen in acute otitis media (AOM), its exact role has not been determined. METHODS: Patients aged 0-18 years with AOM, from whom a specimen of middle-ear fluid was obtained and cultured during 1999-2003, were enrolled. Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and GAS were considered pathogens. Information collected included demographic characteristics, clinical history, and signs and symptoms. RESULTS: GAS otitis was observed in 350 (3.1%) of 11,311 episodes (of which 117 were also culture-positive for other pathogens). The other 10,961 episodes involved H. influenzae only (n = 2507), S. pneumoniae only (n = 2131), dual infection with H. influenzae and S. pneumoniae (n = 1290), M. catarrhalis only (n = 129), and other combinations of pathogens (n = 271). Increased age and Jewish ethnicity were independent, significant, positive risk factors for GAS AOM, and fall season was a negative risk factor. Episodes of GAS infection were less frequently bilateral, febrile, and accompanied by other systemic findings than were other episodes of other types of infection. Most patients with GAS AOM presented with acute drainage from the ears. A lower proportion of cases of AOM were due to GAS in children with recurrent AOM and in patients recently treated with antibiotics, compared with patients with AOM who did not have these factors. The risk for mastoiditis was highest among patients with GAS AOM, compared with patients infected with other pathogens: 11.6 episodes per 1000 episodes of GAS AOM, compared with 2.2, 0.3, and 0 episodes of mastoiditis per 1000 episodes of AOM due to S. pneumoniae, H. influenzae, and M. catarrhalis, respectively. CONCLUSION: Compared with AOM caused by pathogens other than GAS, GAS AOM is characterized by older age and higher local aggressiveness manifested by lower rates of fever and respiratory symptoms and higher rates of tympanic perforation and mastoiditis.

Acute Disease↗
PubMed2005

Nasopharyngeal carriage of Streptococcus pneumoniae at the completion of successful antibiotic treatment of acute otitis media predisposes to early clinical recurrence.

OBJECTIVE: We sought to investigate the role of Streptococcus pneumoniae (SP) nasopharyngeal (NP) colonization after successful antibiotic treatment (Rx) of acute otitis media (AOM) in recurrent AOM (RAOM). PATIENTS AND METHODS: NP cultures were obtained from 494 (93%) of 530 patients at the end of antibiotic treatment (EOT). RESULTS: At enrollment, middle ear fluid (MEF) cultures in 418 (79%) of 530 patients were positive for pathogens. At EOT, NP cultures in 208 (42%) of 494 patients were positive for SP. RAOM was found in 130 (26%) of 494 patients: 66 (32%) of 208 with SP-positive NP and 64 of 286 (22%) without SP-positive NP at EOT (P=.026). MEF was positive for SP during RAOM in 34 (61%) of 56 patients with SP-positive NP and 17 (36%) of 47 patients without SP-positive NP at EOT (P=.022). The same serotype was identified in 24 (80%) of 30 SP pairs; complete identity was found between isolates in 22 (96%) of 23 SP pairs. CONCLUSIONS: Early RAOM was more commonly caused by SP if the organism was present in NP at EOT during the initial AOM episode. Most SP-RAOM episodes were caused by SP isolates present in NP at EOT during the previous AOM episode.

Anti-Bacterial Agents↗
PubMed2005

Are anticapsular antibodies the primary mechanism of protection against invasive pneumococcal disease?

BACKGROUND: Antibody to capsular polysaccharide has been the basis of several vaccines that offer protection against invasive disease from Streptococcus pneumoniae. The success of such vaccines has led to the inference that natural protection against invasive pneumococcal disease is largely conferred by anticapsular antibody. If this is so, one would expect that the decline in disease from different serotypes would vary significantly, and that the appearance of substantial concentrations of anticapsular antibodies would coincide temporally with the decline in age-specific incidence. METHODS AND FINDINGS: Using incidence data from the United States, we show that, on the contrary, the decline in incidence with age is quite similar for the seven most important serogroups, despite large differences in exposure in the population. Moreover, only modest increases in antibody concentration occur over the second and third years of life, a period in which serotype-specific incidence declines to less than 25% of its peak. We also present detailed data on the distribution of antibody concentrations in Israeli toddlers, which are consistent with the United States findings. The same conclusion is supported by new data on age-specific incidence in Finland, which is compared with published data on antibody acquisition in Finnish toddlers. CONCLUSION: We suggest some additional studies of the mechanisms of protection that could distinguish among potential alternative mechanisms, including acquired immunity to noncapsular antigens, maturation of nonspecific immune responses, or changes in anatomy or exposure.

Age Factors↗
PubMed2005

Anemia as a risk factor for infectious diseases in infants and toddlers: results from a prospective study.

Anemia due to iron deficiency is the most prevalent form of micronutrient malnutrition in the world, however, the causal relationship between anemia and infection remains unclear. We examined prospectively, the association between anemia and infection among Bedouin infants. We recruited 293 families and newborns from the Bedouin population, which is ongoing major lifestyle changes, during the periods of 1989-1992 and 1994-1997 and followed them to age 18 months. The number of diarrhea and respiratory disease episodes as well as total days of diarrhea were ascertained weekly. Hemoglobin levels were obtained at age 6 months. Additional data on feeding practices, environmental, household and demographic characteristics were obtained throughout the 18 months. Diarrhea before 6 months of age was found to be a risk factor for diarrhea after that age. After controlling for early morbidity < 6 months, anemia (Hb < 11 g/dl) at 6 months was an independent risk factor for diarrhea and respiratory illness from 7 to 18 months of age. This associations remained significant even after controlling, in addition, for environmental and socio-economic factors. In the multivariable models, anemia at age 6 months increased the risk for diarrhea after that age by 2.9-fold (95% confidence interval 1.6 - 5.3; p = 0.001) and that of respiratory disease by 2-fold (1.1 - 3.7; p = 0.03). Our findings suggest that anemia may increase the rates of infections in toddlers. The possibility that reducing anemia in infants may be a preventive measure to lower disease burden from infectious disease in this and other vulnerable populations should be tested in further studies.

Anemia↗
PubMed2005

Acute otitis media-diagnosis and treatment in the era of antibiotic resistant organisms: updated clinical practice guidelines.

The treatment of children with AOM has to rely on an accurate diagnosis and a clear discrimination between AOM and serous otitis media. The last decade has seen major changes in the epidemiology of AOM with an earlier onset of disease and a greater proportion of children with recurrent/complicated AOM. The processes of changing susceptibility of bacterial pathogens added a major problem in treatment selection. Tastier, more efficient, safe and conveniently-dosing as well as cost effective drugs are required to achieve adherence to therapy. The recent published guidelines for the treatment of AOM in the present era of pneumoccocal resistance represent a major step forward in the approach to the management of this disease by establishing a clear hierarchy among the various therapeutic agents. A 48-72 h observation option without use of antibacterial therapy in selected children with uncomplicated AOM should be promoted. Immunization against S. pneumoniae with the heptavalent pneumococcal conjugated vaccines was showed to result in a decrease in the frequency of AOM caused by this pathogen, including AOM caused by antibiotic-resistant S. pneumoniae.

Acute Disease↗
PubMed2005

Acquisition of Streptococcus pneumoniae and nonspecific morbidity in infants and their families: a cohort study.

BACKGROUND: Most children are believed to acquire Streptococcus pneumoniae asymptomatically, with only a few developing overt S. pneumoniae disease. This study investigates the relationship between acquisition of S. pneumoniae and mild nonspecific infection leading to general practitioner (GP) consultation. METHODS: A prospective birth cohort study of 213 infants assessed at home 9 times during 24 weeks by nasopharyngeal swab and parental interview was conducted. RESULTS: All positive S. pneumoniae swabs (including acquisition and carriage) were significantly associated with GP consultations for infection by the study infant compared with infants with negative swabs [odds ratio (OR), 1.6; 95% confidence interval (CI) 1.1-2.2; P = 0.005]. There was a stronger association with S. pneumoniae acquisition alone (OR 2.1; 95% CI 1.3-3.4; P = 0.001) than with carriage only (OR 1.4; 95% CI 0.9-2.0; P = 0.1). Multivariate analysis confirmed that S. pneumoniae acquisition by the study subject was independently associated with GP consultations: adjusted hazard ratio, 1.8 (95% CI 1.1-2.9); P = 0.02. A similar and independent association was found between S. pneumoniae acquisition by the study subject, and GP consultations for infection by the family (adjusted hazard ratio, 1.8; 95% CI 1.1-2.8; P = 0.01). CONCLUSION: Acquisition of S. pneumoniae by the study infant was significantly associated with GP consultations for infection by the infant or family.

Carrier State↗
PubMed2005

Large dosage amoxicillin/clavulanate, compared with azithromycin, for the treatment of bacterial acute otitis media in children.

BACKGROUND: A large dosage pediatric formulation of amoxicillin/clavulanate with an improved pharmacokinetic/pharmacodynamic profile was developed to eradicate many penicillin-resistant strains of Streptococcus pneumoniae and Haemophilus influenzae (including beta-lactamase-producing strains). METHODS: This randomized, investigator-blinded, multicenter trial examined treatment of bacterial acute otitis media (AOM) in children 6-30 months of age with amoxicillin/clavulanate (90/6.4 mg/kg/d in 2 divided doses for 10 days) versus azithromycin (10 mg/kg for 1 day followed by 5 mg/kg/d for 4 days). Tympanocentesis was performed at entry for bacteriologic assessment, at the on-therapy visit (day 4-6) to determine bacterial eradication and at any time before the end-of-therapy visit (day 12-14) if the child was categorized as experiencing clinical failure. Clinical assessments were performed at the on-therapy, end-of-therapy and follow-up (day 21-25) visits. RESULTS: We enrolled 730 children; AOM pathogens were isolated at baseline for 249 of the amoxicillin/clavulanate group and 245 of the azithromycin group. For children with AOM pathogens at baseline, clinical success rates at the end-of-therapy visit were 90.5% for amoxicillin/clavulanate versus 80.9% for azithromycin (P < 0.01), and those at the on-therapy and follow-up visits were 94.9% versus 88.0% and 80.3% versus 71.1%, respectively (all P < 0.05). At the on-therapy visit, pretherapy pathogens were eradicated for 94.2% of children receiving amoxicillin/clavulanate versus 70.3% of those receiving azithromycin (P < 0.001). Amoxicillin/clavulanate eradicated 96.0% of S. pneumoniae (92.0% of fully penicillin-resistant S. pneumoniae) and 89.7% of H. influenzae (85.7% [6 of 7 cases] of beta-lactamase-positive H. influenzae). Corresponding rates for azithromycin were 80.4% (54.5%) for S. pneumoniae and 49.1% (100% [1 of 1 case]) for H. influenzae (all P < 0.01 for between-drug comparisons). CONCLUSION: Amoxicillin/clavulanate was clinically and bacteriologically more effective than azithromycin among children with bacterial AOM, including cases caused by penicillin-resistant S. pneumoniae and beta-lactamase-positive H. influenzae.

Acute Disease↗
PubMed2005

Middle ear fluid Streptococcus pneumoniae serotype distribution in Costa Rican children with otitis media.

BACKGROUND: Streptococcus pneumoniae conjugate vaccine became available in Costa Rica in 2004. Previous S. pneumoniae middle ear fluid (MEF) data obtained during the period 1999-2001 from Costa Rican children indicated that serotype 19F was the most common type (75%), but more recently other serotypes have become more prevalent. OBJECTIVES: To establish the most common S. pneumoniae serotypes present in the MEF of Costa Rican children with otitis media (OM) and to analyze serotype distribution by demographic factors, disease distribution and antimicrobial susceptibility patterns and assess the potential protection provided by the new conjugated heptavalent S. pneumoniae vaccine in Costa Rican children with OM. METHODS: During 2002 and 2003, 69 S. pneumoniae isolates were obtained from the MEF of Costa Rican children, ages 3-49 months, with OM. Serotyping was performed by the quellung reaction with antisera from Statens Serum Institute, Copenhagen, Denmark. RESULTS: The most common S. pneumoniae serotypes isolated were 19F (26.1%), 6B (14.5%), 9V (8.7%), 16F (8.7%), 14 (5.8%), 23F (5.8%), 3 (5.8%) and 6A (5.8%). Serotype distribution was similar among children younger than 24 months of age or 24 months of age or older and by disease distribution. There was a tendency towards more penicillin- and trimethoprim-sulfamethoxazole-nonsusceptible isolates among vaccine-type strains than among non-vaccine type strains. CONCLUSIONS: The serotype distribution of S. pneumoniae causing pediatric OM in Costa Rica is similar to those reported from developed countries. The current heptavalent pneumococcal conjugate vaccine covers 74% of OM episodes in Costa Rican children.

Anti-Bacterial Agents↗
PubMed2005

Clinical and bacterial characteristics of acute bacterial conjunctivitis in children in the antibiotic resistance era.

BACKGROUND: Acute conjunctivitis is the most common eye disorder in young children. Bacteria are responsible for 54-73% of all cases. The goals of the study were to identify the rates of Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis in cases of bacterial conjunctivitis in children and to define antibiotic resistance rates. METHODS: During a 2-year study period, conjunctival swabs of children 2-36 months old were collected prospectively. Nontypable H. influenzae, S. pneumoniae and M. catarrhalis were defined as the study pathogens. Analyzed variables included demography, clinical presentation, bacteriologic results and susceptibility patterns. RESULTS: There were 428 patients enrolled. Of all cultures, 55% (237 of 428) yielded at least 1 of the study pathogens. H. influenzae and S. pneumoniae were isolated from 29 and 20% of cultures, respectively. beta-Lactamase production was found in 29% of H. influenzae isolates, and penicillin nonsusceptibility was observed in 60% of S. pneumoniae isolates. The most common S. pneumoniae serotypes were: 19F (14%); 6A and 14 (11% each). Nontypable S. pneumoniae was found in 12%. The 7-valent pneumococcal conjugate vaccine (PCV-7) could potentially cover 44% of all isolates. Conjunctivitis-otitis syndrome was found in 32% of patients, of whom 82% of cultures yielded H. influenzae. CONCLUSIONS: Antibiotic resistance rates are alarmingly high. Conjunctivitis-otitis syndrome, predominantly caused by H. influenzae, is quite common. The potential coverage of the PCV-7 in conjunctivitis is relatively lower than that reported in other pneumococcal infections. Our findings should alert physicians on the choice of appropriate antibiotic treatment, on the frequent copresence of acute otitis media and on the potential role of conjunctivitis in the spread of antibiotic-resistant pathogens.

Acute Disease↗
PubMed2005

Superficial skin infection caused by Streptococcus pneumoniae in children.

Pneumococcal superficial skin infections are rarely described. We present 3 cases of Streptococcus pneumoniae superficial skin infections in previously healthy children. In 2 cases, lesions occurred on facial skin; in the third case they occurred on the scrotal raphe. One isolate was fully penicillin-resistant.

Cheek↗
PubMed2005

Community-acquired pneumonia in children: quantifying the burden on patients and their families including decrease in quality of life.

OBJECTIVES: Childhood respiratory infections have an important impact on society and are a frequent cause of physician visits, consumption of antibiotics and over-the-counter drugs, work loss, and reduction of quality of life. The aim of this study was to assess the burden of community-acquired pneumonia (CAP) on children and their families, including quantification of expenses and decrease in quality of life. METHODS: Patients <3 years old with pneumonia were enrolled in 3 sites in southern Israel: pediatric wards, the pediatric emergency department, and a primary health clinic. In the primary health clinic, the diagnosis was based on clinical judgment, and in the hospital the diagnosis was based on the World Health Organization Standardization of Interpretation of Chest Radiographs for the diagnosis of CAP in children. Data regarding the children's medical history and various aspects of direct and indirect burden were gathered every 2 to 3 days during the 29 days of follow-up. The patients' parents were asked to give the names of 2 healthy children who could serve as controls from among the child's friends, neighbors, or day care center attendees. RESULTS: Two-hundred thirteen children with pneumonia were enrolled: 34 (16.0%) in the pediatric wards, 73 (34.2%) in the pediatric emergency department, and 106 (49.8%) in the primary pediatric clinic. The control group consisted of 99 children. During the 29 follow-up days, hospitalized children had the most severe and prolonged symptoms, followed in decreasing order by children seen at the emergency department, primary health clinic, and controls: The mean +/- standard deviation (SD) of febrile days was 4.9 +/- 2.8, 4.8 +/- 3.1, 3.3 +/- 2.5, and 1.4 +/- 3.3, respectively (statistically significant between any patient group and the control group). The mean duration of respiratory distress +/- SD was 3.8 +/- 5.6, 2.8 +/- 4.4, 2.2 +/- 4.4, and 0.4 +/- 1.8 days, respectively (statistically significant between any patient group and the control group). The median duration of nonroutine days as judged by the parents was 13, 8, 7, and 0, respectively. The mean number of workdays lost by working mothers +/- SD was 4.2 +/- 4.8, 2.0 +/- 2.6, 1.7 +/- 1.9, and 0.2 +/- 0.9, respectively (between any patient group and the control group). The quality-of-life-questionnaire analysis reveals statistically significant differences with regard to all 11 questions asked between any of the patient groups and the control group. There was a clear trend toward decreasing quality of life from the control group to the primary health clinic, pediatric emergency department, and pediatric wards groups. CONCLUSIONS: CAP in children causes a significant burden on both patients and their families, including substantial expenses, loss of routine, and decrease in quality of life.

Caregivers↗
PubMed2005

Community prescribing and resistant Streptococcus pneumoniae.

We investigated the association between prescribing antimicrobial agents and antimicrobial resistance of Streptococcus pneumoniae among children with acute otitis media in southern Israel. During a 6-year period, all prescriptions of a sample of approximately 20% of Jewish and Bedouin children <5 years of age were recorded and all pneumococcal isolates from middle ear fluid were collected. Although antimicrobial drug use was significantly higher in Bedouin children, the proportion of S. pneumoniae isolates with penicillin MIC = or > 1.0 microg/mL was significantly higher in Jewish children. In both populations, antimicrobial prescriptions were markedly reduced over time, especially for penicillins and erythromycin. In contrast, azithromycin prescriptions increased from 1998 to 2001 with a parallel increase in macrolide and multidrug resistance. Penicillin resistance was associated with macrolide resistance. These findings strongly suggest that azithromycin affects increased antimicrobial resistance, including multidrug resistance, in S. pneumoniae.

Acute Disease↗
PubMed2005

[Infectious complications with herpes virus after ritual Jewish circumcision: a historical and cultural analysis].

Ritual circumcision performed on eight-day-old male infants is rooted in the Bible and is discussed in the earliest Jewish sources. The practice has been observed across the generations in every Jewish community in Israel and the Diaspora. According to Jewish ritual, the mohel--the ritual circumcisor--amputates the foreskin and then folds back the membrane that lies beneath it. This is followed by metzitza--"suction"--a practice performed throughout the ages by mouth. Halakhic literature sets down strict rules regarding this surgical intervention in order to prevent medical complications for the newborn. Metzitza by mouth has been recognized as a risk factor in the transfer of infection from the mohel to the newborn. A recent study relates to eight infants who became infected with herpes virus as a result of the procedure. We shall review the halakhic literature in order to clarify the custom of metzitza by mouth and understand the principles underlying the controversy that surrounds it. The custom of metzitza by mouth has been the subject of extensive rabbinic discussion since the middle of the nineteenth century. A better understanding of the historical, social and cultural background of the issue might allow us to formulate alternatives to the practice. The metzitza controversy gave rise to a stimulating discussion in the rabbinic literature with diverse and conflicting opinions. We shall undertake a precise analysis of the rabbinic discussion and its historical and social background, and attempt to identify the ideological underpinnings of the various positions. Rabbinic literature is replete with cautionary measures to be observed when circumcising a newborn child. The halakhic disputes beginning in the middle of the nineteenth century reflect ideological considerations and objectives. Metzitza was performed throughout the generations by mouth because that was the recognized method of disinfection at the time. Beginning in the nineteenth century, medical and esthetic considerations have led to the abolishment of metzitza by mouth or to its performance by way of a swab or through a glass tube in order to prevent infection. Ideological tendentiousness is evident in both approaches: Should the medical risks of metzitza by mouth be overlooked and denied out of loyalty to ancient tradition, thus allowing the practice to be continued? Or should the recognition of such risks along with esthetic considerations lead to changes in halakhic thinking to perform the metzitza in a hygienic technique? Historically, the issue of metzitza by mouth has been a bone of contention between traditional outlook and modern halakhic thinking, which takes into consideration advances in medical knowledge. In light of the reports in the medical literature about complications in the wake of metzitza by mouth, some of the halakhic rulings regarding circumcision should be reconsidered. Clinically, it is important to raise the medical community's awareness of the phenomenon and treat infected infants accordingly.

Circumcision, Male↗
PubMed2004

Emergence of penicillin-nonsusceptible Streptococcus pneumoniae clones expressing serotypes not present in the antipneumococcal conjugate vaccine.

BACKGROUND: Penicillin-nonsusceptible Streptococcus pneumoniae isolates are confined mainly to a few serogroups. Capsular transformation may serve as a mechanism for spreading antibiotic resistance to new serotypes. METHODS: Antibiogram and molecular typing, by pulsed-field gel electrophoresis (PFGE), were performed on 46 nasopharyngeal and middle ear fluid (MEF) isolates expressing serotype 11A, 45 MEF isolates expressing serotype 15B/C (recovered during 1998-2003 from Israeli children <5 years old), and 57 MEF isolates expressing serotype 19F (recovered during 1998-2001 from Costa Rican children <7.5 years old). RESULTS: PFGE patterns showed that 49 (86%) of 57 serotype 19F isolates and 19 (41%) of 46 serotype 15B/C isolates were closely related. The vast majority of these isolates (80% of serotype 19F and 100% of serotype 15B/C isolates) were nonsusceptible to penicillin. Multilocus sequence typing (MLST) data show that the serotype 15B/C isolates belonged to the ST346 cluster, whereas the serotype 19F isolates were a single-locus variant of ST346. For serotype 11A isolates, PFGE patterns and MLST analysis showed that 8 (80%) of the 10 penicillin-nonsusceptible isolates belonged to a single clone--namely, ST156--which was identical to the international Spain9V-3 clone. CONCLUSIONS: Penicillin-nonsusceptible pneumococcal clones of serotypes not related to those included in the 11-valent conjugate vaccines may derive from capsular transformation of vaccine-related serotypes. Of particular concern was the detection of serotype 11A variants of the successful international Spain9V-3 clone. This phenomenon, although seemingly rare at present, can have implications for the long-term effectiveness of the conjugate vaccines.

Child↗
PubMed2004

Association between carriage of Streptococcus pneumoniae and Staphylococcus aureus in Children.

CONTEXT: Widespread pneumococcal conjugate vaccination may bring about epidemiologic changes in upper respiratory tract flora of children. Of particular significance may be an interaction between Streptococcus pneumoniae and Staphylococcus aureus, in view of the recent emergence of community-acquired methicillin-resistant S aureus. OBJECTIVE: To examine the prevalence and risk factors of carriage of S pneumoniae and S aureus in the prevaccination era in young children. DESIGN, SETTING, AND PATIENTS: Cross-sectional surveillance study of nasopharyngeal carriage of S pneumoniae and nasal carriage of S aureus by 790 children aged 40 months or younger seen at primary care clinics in central Israel during February 2002. MAIN OUTCOME MEASURES: Carriage rates of S pneumoniae (by serotype) and S aureus; risk factors associated with carriage of each pathogen. RESULTS: Among 790 children screened, 43% carried S pneumoniae and 10% carried S aureus. Staphylococcus aureus carriage among S pneumoniae carriers was 6.5% vs 12.9% in S pneumoniae noncarriers. Streptococcus pneumoniae carriage among S aureus carriers was 27.5% vs 44.8% in S aureus noncarriers. Only 2.8% carried both pathogens concomitantly vs 4.3% expected dual carriage (P =.03). Risk factors for S pneumoniae carriage (attending day care, having young siblings, and age older than 3 months) were negatively associated with S aureus carriage. CONCLUSIONS: Streptococcus pneumoniae carriage, specifically of vaccine-type strains, is negatively associated with S aureus carriage in children. The implications of these findings in the pneumococcal vaccine era require further investigation.

Carrier State↗