Emergence of Streptococcus pneumoniae Serotype 12F after Sequential Introduction of 7- and 13-Valent Vaccines, Israel

Israel implemented use of 7- and 13-valent pneumococcal vaccine in 2009 and 2010, respectively. We describe results of prospective, population-based, nationwide active surveillance of Streptococcus pneumoniae serotype 12F (Sp12F) invasive pneumococcal disease (IPD) dynamics in the 7 years after vaccine introduction. Of 4,573 IPD episodes during July 2009-June 2016, a total of 434 (9.5%) were caused by Sp12F. Sp12F IPD rates (cases/100,000 population) increased in children <5 years of age, from 1.44 in 2009-2010 to >3.9 since 2011-2012, followed by an increase in all ages. During 2011-2016, Sp12F was the most prevalent IPD serotype. Sp12F isolates were mostly penicillin nonsusceptible (MIC >0.06 µg/mL; MIC₅₀ = 0.12) and predominantly of sequence type 3774), a clone exclusively found in Israel (constituting ≈90% of isolates in 2000-2009). The sharp increase, long duration, and predominance of Sp12F IPD after vaccine implementation reflect a single clone expansion and may represent more than a transient outbreak.

Flavin Reductase Contributes to Pneumococcal Virulence by Protecting from Oxidative Stress and Mediating Adhesion and Elicits Protection Against Pneumococcal Challenge

Pneumococcal flavin reductase (FlaR) is known to be cell-wall associated and possess age dependent antigenicity in children. This study aimed at characterizing FlaR and elucidating its involvement in pneumococcal physiology and virulence. Bioinformatic analysis of FlaR sequence identified three-conserved cysteine residues, suggesting a transition metal-binding capacity. Recombinant FlaR (rFlaR) bound Fe²⁺ and exhibited FAD-dependent NADP-reductase activity, which increased in the presence of cysteine or excess Fe²⁺ and inhibited by divalent-chelating agents. flaR mutant was highly susceptible to H₂O₂ compared to its wild type (WT) and complemented strains, suggesting a role for FlaR in pneumococcal oxidative stress resistance. Additionally, flaR mutant demonstrated significantly decreased mice mortality following intraperitoneal infection. Interestingly, lack of FlaR did not affect the extent of phagocytosis by primary mouse peritoneal macrophages but reduced adhesion to A549 cells compared to the WT and complemented strains. Noteworthy are the findings that immunization with rFlaR elicited protection in mice against intraperitoneal lethal challenge and anti-FlaR antisera neutralized bacterial virulence. Taken together, FlaR's roles in pneumococcal physiology and virulence, combined with its lack of significant homology to human proteins, point towards rFlaR as a vaccine candidate.

CodY Regulates Thiol Peroxidase Expression as Part of the Pneumococcal Defense Mechanism against H2O2 Stress

Streptococcus pneumoniae is a facultative anaerobic pathogen. Although it maintains fermentative metabolism, during aerobic growth pneumococci produce high levels of H₂O₂, which can have adverse effects on cell viability and DNA, and influence pneumococcal interaction with its host. The pneumococcus is unusual in its dealing with toxic reactive oxygen species (ROS) in that it neither has catalase nor the global regulators of peroxide stress resistance. Previously, we identified pneumococcal thiol peroxidase (TpxD) as the key enzyme for enzymatic removal of H₂O₂, and showed that TpxD synthesis is up-regulated upon exposure to H₂O₂. This study aimed to reveal the mechanism controlling TpxD expression under H₂O₂ stress. We hypothesize that H₂O₂ activates a transcription factor which in turn up-regulates tpxD expression. Microarray analysis revealed a pneumococcal global transcriptional response to H₂O₂. Mutation of tpxD abolished H₂O₂-mediated response to high H₂O₂ levels, signifying the need for an active TpxD under oxidative stress conditions. Bioinformatic tools, applied to search for a transcription factor modulating tpxD expression, pointed toward CodY as a potential candidate. Indeed, a putative 15-bp consensus CodY binding site was found in the proximal region of tpxD-coding sequence. Binding of CodY to this site was confirmed by EMSA, and genetic engineering techniques demonstrated that this site is essential for TpxD up-regulation under H₂O₂ stress. Furthermore, tpxD expression was reduced in a ΔcodY mutant. These data indicate that CodY is an activator of tpxD expression, triggering its up-regulation under H₂O₂ stress. In addition we show that H₂O₂ specifically oxidizes the 2 CodY cysteines. This oxidation may trigger a conformational change in CodY, resulting in enhanced binding to DNA. A schematic model illustrating the contribution of TpxD and CodY to pneumococcal global transcriptional response to H₂O₂ is proposed.

Outbreaks of Invasive Kingella kingae Infections in Closed Communities

OBJECTIVES

To describe the results of the epidemiologic investigation of outbreaks of invasive Kingella kingae infections among attendees at daycare facilities located in 4 closed communities in Israel.

STUDY DESIGN

The preschool-aged population of communities with clusters of Kingella cases had oropharyngeal cultures performed. K kingae isolates from infected patients and healthy contacts were genotyped by pulsed field gel electrophoresis to determine the spread of outbreak strains.

RESULTS

The affected closed communities (3 military bases and 1 "kibbutz" commune) were characterized by tight social and family networks and intensive mingling. The outbreaks affected 9 of 51 attendees (attack rate: 17.6%) age 8-19 months (median: 12 months), within a 21-day period. Cases included skeletal system infections (n = 8) and bacteremia (n = 1); K kingae isolates were confirmed by the use of blood culture vials and selective media. Clinical presentation was mild and acute-phase reactants were usually normal or only moderately elevated. Thirty out of 55 (54.5%) asymptomatic children carried the outbreak strains. Analysis of the 3 clusters in which the entire preschool-aged population was cultured revealed that 31 of 71 (43.7%) children younger than 24 months of age were colonized with K kingae organisms compared with 8 of 105 (7.6%) older children (P < .001).

CONCLUSIONS

Clusters of invasive K kingae infections characterized by sudden onset, high attack rate, and wide dissemination of the outbreak strain can occur in daycare facilities and closed communities. Because the mild clinical presentation of invasive K kingae infections and the fastidious nature of the organism, a high index of suspicion and use of sensitive detection methods are recommended.

Etiology and antimicrobial susceptibility of middle ear fluid pathogens in Costa Rican children with otitis media before and after the introduction of the 7-valent pneumococcal conjugate vaccine in the National Immunization Program: acute otitis media microbiology in Costa Rican children

Acute otitis media (AOM) microbiology was evaluated in children after 7-valent pneumococcal conjugate vaccine (PCV7) introduction in Costa Rica (private sector, 2004; National Immunization Program, 2009). This was a combined prospective and retrospective study conducted in a routine clinical setting in San José, Costa Rica. In the prospective part of the study, which was conducted post-PCV7 introduction (2010-2012), standard bacteriological procedures were used to evaluate the etiology and serotype distribution of middle ear fluid samples collected by tympanocentesis or otorrhea from children aged 3-59 months diagnosed with AOM. E-tests were used to evaluate antimicrobial susceptibility in culture-positive samples. Retrospective data recorded between 1999 and 2004 were used for comparison of bacterial etiology and serotype distribution before and after PCV7 introduction. Statistical significance was evaluated in bivariate analyses at the P-value < 0.05 level (without multiplicity correction). Post-PCV7 introduction, Haemophilus influenzae was detected in 118/456 and Streptococcus pneumoniae in 87/456 AOM episodes. Most H. influenzae isolates (113/118) were non-typeable. H. influenzae was more (27.4% vs 20.8%) and S. pneumoniae less (17.1% vs 25.5%) frequently observed in vaccinated (≥ 2 PCV7 doses or ≥ 1 PCV7 dose at >1 year of age) versus unvaccinated children. S. pneumoniae non-susceptibility rates were 1.1%, 34.5%, 31.7%, and 50.6% for penicillin, erythromycin, azithromycin, and trimethoprim/sulfamethoxazole (TMP-SMX), respectively. H. influenzae non-susceptibility rate was 66.9% for TMP-SMX. Between pre- and post-PCV7 introduction, H. influenzae became more (20.5% vs 25.9%; P-value < 0.001) and S. pneumoniae less (27.7% vs 19.1%; P-value = 0.002) prevalent, and PCV7 serotype proportions decreased among pneumococcal isolates (65.8% vs 43.7%; P-value = 0.0005). Frequently identified pneumococcal serotypes were 19F (34.2%), 3 (9.7%), 6B (9.7%), and 14 (9.7%) pre-PCV7 introduction, and 19F (27.6%), 14 (8.0%), and 35B (8.0%) post-PCV7 introduction. Following PCV7 introduction, a change in the distribution of AOM episodes caused by H. influenzae and pneumococcal serotypes included in PCV7 was observed in Costa Rican children. Pneumococcal vaccines impact should be further evaluated following broader vaccination coverage.

Persistence and complex evolution of fluoroquinolone-resistant Streptococcus pneumoniae clone

This clone has persisted in a post–acute care facility for >5 years.

Prolonged outbreaks of multidrug-resistant Streptococcus pneumoniae in health care facilities are uncommon. We found persistent transmission of a fluroquinolone-resistant S. pneumoniae clone during 2006–2011 in a post–acute care facility in Israel, despite mandatory vaccination and fluoroquinolone restriction. Capsular switch and multiple antimicrobial nonsusceptibility mutations occurred within this single clone. The persistent transmission of fluoroquinolone-resistant S. pneumoniae during a 5-year period underscores the importance of long-term care facilities as potential reservoirs of multidrug-resistant streptococci.

Efficacy of 13-valent pneumococcal conjugate vaccine (PCV13) versus that of 7-valent PCV (PCV7) against nasopharyngeal colonization of antibiotic-nonsusceptible Streptococcus pneumoniae

BACKGROUND

Pediatric respiratory infections caused by antibiotic-nonsusceptible Streptococcus pneumoniae (ANSP) continue to present an important challenge, even after introduction of 7-valent pneumococcal conjugate vaccine (PCV7). This randomized double-blind trial assessed the potential additional impact of PCV13 over PCV7 on reducing ANSP carriage.

METHODS

Healthy infants were randomly assigned to receive PCV13 (n = 932) or PCV7 (n = 934) at ages 2, 4, 6, or 12 months. Eight nasopharyngeal specimens were collected by swabbing between ages 2 and 24 months. S. pneumoniae isolates were serotyped and tested for antimicrobial susceptibility by the disk-diffusion method and the Etest. Nasopharyngeal acquisition and prevalence of ANSP during ages 7-24 months were compared between the 2 vaccine groups.

RESULTS

In general, new acquisition of pneumococci nonsusceptible to penicillin, erythromycin, clindamycin, penicillin plus erythromycin, and multiple drugs (≥3 antibiotics) was significantly lower in the PCV13 group compared with the PCV7 group; the main serotypes contributing to this significant decrease were serotype 19F, present in PCV13 and PCV7, and serotypes 6A and 19A, present in PCV13 only.

CONCLUSIONS

PCV13 has a significant added benefit over PCV7 in reducing carriage of ANSP. Because carriage determines transmission, these results suggest that PCV13 will provide protection against ANSP disease that exceeds protection provided by PCV7.

CLINICAL TRIALS REGISTRATION

NCT00508742.

Age-Dependent Carriage of Kingella kingae in Young Children and Turnover of Colonizing Strains

In a longitudinal study, Kingella kingae carriage rate was nil below 6 months of age, 1.5% at 6 months, 9.6% at 12 months, remained stable between 10.4% and 12.0% during the second year of life, and decreased significantly to 5.3% at 30 months. Replacement of carried strains occurred over time.

Comparative immunogenicity and efficacy of 13-valent and 7-valent pneumococcal conjugate vaccines in reducing nasopharyngeal colonization: a randomized double-blind trial

BACKGROUND

The 13-valent pneumococcal conjugate vaccine (PCV13) was licensed to replace the 7-valent pneumococcal conjugate vaccine (PCV7) based on serological noninferiority criteria. To date no randomized PCV13 pediatric trial has included clinical endpoints.

METHODS

This randomized double-blind trial compared the impact of PCV13 versus PCV7 on nasopharyngeal (NP) colonization and immunogenicity. Healthy infants were randomized (1:1) to receive PCV7 or PCV13 at ages 2, 4, 6, and 12 months; NP swabs were collected at 2, 4, 6, 7, 12, 13, 18, and 24 months, and blood was drawn at 7 and 13 months. Rates of NP acquisition and prevalence, and serotype-specific immunoglobulin G (IgG) concentrations were assessed.

RESULTS

The per protocol analysis population included 881 PCV13 and 873 PCV7 recipients. PCV13 significantly reduced NP acquisition of the additional PCV13 serotypes 1, 6A, 7F, and 19A; the cross-reacting serotype 6C; and the common PCV7 serotype 19F. For serotype 3, and the other PCV7 serotypes, there were no significant differences between the vaccine groups. There were too few serotype 5 events to draw inference. The impact on prevalence at predefined time points was similar to that observed with NP acquisition. PCV13 elicited significantly higher IgG responses for PCV13 additional serotypes and serotype 19F, and similar or lower responses for 6/7 PCV7 serotypes.

CONCLUSIONS

PCV13 resulted in lower acquisition and prevalence of NP colonization than PCV7 did for 4 additional PCV13 serotypes, and serotypes 6C and 19F. It was comparable with PCV7 for all other common serotypes. These findings predict vaccine effectiveness through both direct and indirect protection.

CLINICAL TRIALS REGISTRATION

NCT00508742.

Multilocus sequence typing and rtxA toxin gene sequencing analysis of Kingella kingae isolates demonstrates genetic diversity and international clones

Background

Kingella kingae, a normal component of the upper respiratory flora, is being increasingly recognized as an important invasive pathogen in young children. Genetic diversity of this species has not been studied.

Methods

We analyzed 103 strains from different countries and clinical origins by a new multilocus sequence-typing (MLST) schema. Putative virulence gene rtxA, encoding an RTX toxin, was also sequenced, and experimental virulence of representative strains was assessed in a juvenile-rat model.

Results

Thirty-six sequence-types (ST) and nine ST-complexes (STc) were detected. The main STc 6, 14 and 23 comprised 23, 17 and 20 strains respectively, and were internationally distributed. rtxA sequencing results were mostly congruent with MLST, and showed horizontal transfer events. Of interest, all members of the distantly related ST-6 (n = 22) and ST-5 (n = 4) harboured a 33 bp duplication or triplication in their rtxA sequence, suggesting that this genetic trait arose through selective advantage. The animal model revealed significant differences in virulence among strains of the species.

Conclusion

MLST analysis reveals international spread of ST-complexes and will help to decipher acquisition and evolution of virulence traits and diversity of pathogenicity among K. kingae strains, for which an experimental animal model is now available.

Streptococcus pneumoniae serotypes isolated from the middle ear fluid of Costa Rican children following introduction of the heptavalent pneumococcal conjugate vaccine into a limited population

BACKGROUND

The heptavalent pneumococcal conjugate vaccine (PCV-7) was introduced in high risk children and into the private market in Costa Rica in 2004 (<5% annual birth cohort). The aim of this study was to compare the Streptococcus pneumoniae serotype (ST) distribution, antibiotic resistance patterns and potential coverage before and after partial introduction of PCV-7.

METHODS

A comparison between the S. pneumoniae isolates obtained and serotyped from the middle ear fluid (MEF) of Costa Rican children with otitis media between years 1999 and 2003 (before PCV-7 usage) and those isolates obtained from 2004 to 2008.

RESULTS

A total of 145 and 218 MEF S. pneumoniae were serotyped between years 1999 and 2003 and 2004 and 2008, respectively. Considering a 19F outbreak observed between years 1999 and 2003, the following statistically significant changes in serotype distribution were detected between 1999 and 2003 and 2004 and 2008: ST 3: 4.8-12.8% (P=0.01); ST 11A: 0-4.1% (P=0.01); ST 14: 3.5-21.1% (P<0.001) and ST 19F: 52.4-18.3% (P<0.05). Comparison of the two study periods demonstrated that during 2004 and 2008 a statistically significant decrease in penicillin non-susceptible serotypes (36.2-20.4% [P=0.003]) and a statistically significant increase in trimethoprim-sulfametoxazole resistant serotypes (54.9-68.5%, respectively [P=0.03]) was observed. Potential pneumococcal vaccines coverage between 1999 and 2003 and between 2004 and 2008 were: for PCV-7: 77.2-60.5%, respectively (P=0.001); for the 10-valent conjugated vaccine (PCV-10): 78.6-61.4%, respectively (P=0.0008) and for the 13-valent conjugated vaccine (PCV-13): 84.8-79.3%, respectively (P=0.2).

CONCLUSIONS

Changes in the serotype distribution and antimicrobial susceptibility of MEF S. pneumoniae have been observed in Costa Rican children with OM. Because of the limited use of PCV-7 during the study period, these changes probably cannot be attributed to PCV-7 use. Between 2004 and 2008, PCV-13 offered the highest potential vaccine coverage.

Differential occurrence of Streptococcus pneumoniae serotype 11E between asymptomatic carriage and invasive pneumococcal disease isolates reflects a unique model of pathogen microevolution

BACKGROUND

Streptococcus pneumoniae is a commensal colonizer of the human nasopharynx (NP) that causes disease after evasion of host defenses and dissemination. Pneumococcal strains expressing the newly identified serotype 11E arise from antigenically similar 11A progenitors by genetic inactivation of the O-acetyltransferase gene wcjE. Each 11E strain contains a distinct mutation to wcjE, suggesting that 11E strains are not transmitted among hosts despite their recovery from multiple patients with pneumococcal disease. We investigated whether the presumed lack of transmission of serotype 11E is consistent with its inability to survive in the NP.

METHODS

More than 400 pneumococcal carriage, middle ear, conjunctiva, and blood isolates, serotyped as 11A by Quellung reaction, were reexamined for reactivity to 11A- and 11E-specific antibodies. We confirmed serotyping of isolates with sequencing of wcjE alleles.

RESULTS

Serotype 11E strains were statistically more likely to occur among blood (4 of 15), conjunctiva (1 of 14), or middle ear (2 of 21) isolates than among carriage isolates (2 of 355). All 11E isolates contained unique mutations that putatively decrease wcjE expression.

CONCLUSIONS

The lack of a circulating 11E clone and the increased occurrence of 11E strains among disease isolates supports the idea that serotype 11E independently arises during infection after initial colonization with a serotype 11A progenitor. Factors encountered in the NP likely contribute to relative rarity of 11E among carriage isolates, whereas selective pressures in deeper tissues possibly promote 11E emergence. These findings illustrate a novel model of microevolution that transpires during the span of a single encounter with serotype 11A, highlighting the adaptability of bacterial pathogens within hosts.

Appropriateness of viscoelastic soft materials as in vitro simulators of the periodontal ligament

The periodontal ligament is a viscoelastic soft tissue that connects the tooth to the alveolar bone. This tissue should be simulated in numerical as well as in laboratory models. The mechanical properties of this tissue were previously determined ex vivo and in vivo. The aim of the study was to analyse the appropriateness of impression and reline materials used in dentistry to simulate viscoelastic behaviour of the periodontal ligament. Two reline [Durabase (Reliance Dental MFG, Co.) and Soft Liner (GC Corporation)] and two impression [President Plus (Coltene) and Prestige L (Vanini Dental Industry)] materials were examined in recovery and tensile relaxation tests. Recovery: This experiment simulated in vivo test. Roots of a pair of plastic maxillary premolar teeth were covered with each test material and embedded in acryl while maintaining the contact point. A 0·1-mm stainless steel strip, inserted at the contact point and maintained for 10 s, was used to tip the teeth. After removal, the tightness of dental contact point was measured over 30 min by determining the force needed to insert a 0·05-mm metal strip. Tensile relaxation: strips were elongated to 120%, 140% and 160% of their initial length and maintained at that length for 30 min. Two-phase decay function was applied. The results showed that elastic modulus and relaxation behaviour were significantly different between materials. Elastic modulus values were in the same range of those reported in the literature. However, the recovery values and behaviour showed that impression materials, especially President, are the materials of choice for this purpose because they simulated better the in vivo test.

Distribution, dynamics and antibiotic resistance patterns of Streptococcus pneumoniae serotypes causing acute otitis media in children in southern Israel during the 10 year-period before the introduction of the 7-valent pneumococcal conjugate vaccine

OBJECTIVES

To determine the dynamics of serotype prevalence, potential coverage by pneumococcal conjugate vaccines (PCV) and antibiotic resistance patterns of Streptococcus pneumoniae causing acute otitis media (AOM) in children in southern Israel before PCV7 introduction in the routine immunization program in Israel.

METHODS

All S. pneumoniae isolates from middle ear fluid from children with AOM during 1999-2008 were included. Prospectively collected demographic data on S. pneumoniae serotypes and antibiotic resistance patterns were analyzed.

RESULTS

A total of 14,911 tympanocenteses yielded 5281 (35%) S. pneumoniae. Proportion of S. pneumoniae-AOM did not vary significantly (overall 35%; 33% in 2007; 38% in 2002 and 2003). The most frequent serotypes were 19F, 14, 23F and 19A; in both Jewish and Bedouin children; serotypes 6A and 19A contributed 6% and 10%, respectively, of all S. pneumoniae isolates. Serotypes included in PCV7, PCV10 and PCV13 represented 60%, 64%, 85% in Jewish children vs. 49%, 55% and 74%, respectively, in Bedouin children (P < 0.001). Nonsusceptibility to TMP/SMX decreased significantly, in parallel with a significant increase in the nonsusceptibility to erythromycin, clindamycin and in multidrug resistant (MDR) isolates. No changes were recorded in the proportion of S. pneumoniae isolates with penicillin MIC ≥ 1.0 μg/ml. The proportion of penicillin- and erythromycin-nonsusceptible and of MDR serotype 6A and 19A isolates increased significantly in Bedouin children.

CONCLUSIONS

(1) No significant changes were recorded in the yearly proportions of serotypes 23F, 19F, 19A, 14 and 6A in both ethnic populations; (2) Potential coverage of the 3 PCVs was higher in Jewish children than in Bedouin children; (3) The relatively high coverage of macrolides- and multidrug-resistant S. pneumoniae by PCV13 and lack of increase in penicillin, erythromycin and multidrug nonsusceptibility among non-PCV13 isolates is encouraging.

Use of colour-coded labels for intravenous high-risk medications and lines to improve patient safety

PROBLEM

Labelling of high-risk drug infusions and lines is a well-recognised safety strategy to prevent medication errors. Although hospital wards characterised by multiple high-risk drug infusions use different types of labelling, little is known about the contribution of a colour-coded label (CCL) to patient safety.

SETTING

A quality improvement programme audit at a tertiary care facility, the Hadassah University Medical Center Ein Kerem, Jerusalem, Israel.

STRATEGY FOR CHANGE

A CCL for intravenous (IV) high-risk medications and lines was designed to promote safer medication administration at the intensive care unit bedside and in other acute wards.

METHODS

The purpose of the study was to compare a new CCL method (intervention) with the current labelling method (control). Laboratory simulation, imitating an intensive care unit, was designed. Safety of the medication treatment and overall duration of nurses' orientation with drugs and lines at the patient's bedside were measured.

EFFECTS OF CHANGE

The use of the new CCL improved proper identification of IV bags (p<0.0001), reduced the time required for description of overall drugs and lines (p = 0.04), improved identification of errors at the treatment setting-drugs and lines (p = 0.03) and reduced the average performance time for overall tasks (p<0.0001).

LESSONS LEARNT

The use of CCLs for IV high-risk medications and lines can improve patient safety and improve medical staff efficiency.

Control of Streptococcus pneumoniae serotype 5 epidemic of severe pneumonia among young army recruits by mass antibiotic treatment and vaccination

During an outbreak of severe pneumonia among new army recruits, an epidemiological investigation combined with repeated nasopharyngeal/oropharyngeal cultures from sick and healthy contacts subjects was conducted. Fifteen pneumonia cases and 19 influenza-like illness cases occurred among 596 recruits over a 4-week period in December 2005. Pneumonia attack rates reached up to 5.5%. A single pneumococcus serotype 5 clone was isolated from blood or sputum cultures in 4 patients and 30/124 (24.1%) contacts. Immunization with 23-valent polysaccharide vaccine supplemented with a 2-dose azithromycin mass treatment rapidly terminated the outbreak. Carriage rates dropped to <1%, 24 and 45 days after intervention.

Increasing importance of multidrug-resistant serotype 6A Streptococcus pneumoniae clones in acute otitis media in southern Israel

BACKGROUND

The major aim of this study was to establish the molecular epidemiology dynamics of Streptococcus pneumoniae serotype 6A in acute otitis media, before the introduction of the 7-valent pneumococcal conjugate vaccine.

METHODS

Acute otitis media in Jewish and Bedouin children <5 years old undergoing tympanocentesis during 1999 to 2006, were studied. Serotype 6A was identified by the Quellung reaction and by polymerase chain reaction (PCR) of the wciN gene, to differentiate between 6A and 6C. Antibiogram and molecular typing by pulsed field gel electrophoresis were performed on all 6A isolates. Multilocus sequence typing was performed on representative isolates of each clone. The 7-valent conjugate vaccine had not yet been licensed in Israel during the study period.

RESULTS

Serotype 6A constituted 5.8% (254/4408) of all pneumococcal acute otitis media episodes. The yearly proportion of serotype 6A among the Jewish children showed no distinct trend, whereas among the Bedouin children serotype 6A exhibited a significant increase, from 3.0% in 1999 to 7.6% in 2006. Among the Jewish children a single penicillin-nonsusceptible and erythromycin-resistant clone, ST-473, constituted 73.6% of the strains and dominated throughout the study period. Among the Bedouin children, the proportions of the most common, penicillin-nonsusceptible clone, ST-1988, gradually decreased, from 44.1% in 1999 to 2000 to 21.4% in 2005 to 2006, concurrently with the expansion of a multidrug-resistant clone, ST-457, from 5.9% in 1999 to 2000 to 28.6% in 2005 to 2006.

CONCLUSIONS

The expansion of multidrug-resistant serotype 6A clone occurred before the introduction of the vaccine. Continued surveillance following vaccine introduction is warranted to further investigate its efficacy on vaccine-related serotypes.

Streptococcus pneumoniae serotype 3 among Costa Rican children with otitis media: clinical, epidemiological characteristics and antimicrobial resistance patterns

BACKGROUND

After the introduction of the seven valent-pneumococcal conjugated vaccine into our National Immunization Program, it is important to establish and track local serotype distribution in order to evaluate its impact specially because serotype replacement phenomena has been described.To describe the clinical, epidemiological and antimicrobial resistance patterns of Costa Rican children with otitis media caused by Streptococcus pneumoniae serotype 3.

METHODS

Middle ear fluid samples were obtained from Costa Rican children with otitis media who participated in various antimicrobial clinical trials between 1992 and 2007. Streptococcus pneumoniae was identified according to laboratory standard procedures. Strains were serotyped and antimicrobial susceptibility to penicillin, amoxicillin, cefuroxime, ceftriaxone, azithromycin and levofloxacin was determined by E-test.

RESULTS

Throughout 1992-2007 a total of 1919 tympanocentesis were performed in children with otitis media (median age: 19 months) and yielded a total of 1208 middle ear isolates. The most common pathogens were: Streptococcus pneumoniae, 511 isolates (49%); Non-Typable Haemophilus influenzae, 386 isolates (37%); Moraxella catarrahalis, 100 isolates (9.5%); and Streptococcus pyogenes, 54 isolates (5%). Streptococcus pneumoniae serotyping was performed in 346/511 isolates (68%) recovered during years 1999-2006. The most common serotypes were 19F (101/30.0%), 14 (46/13.7%), 3 (34/10.1%), 6B (30/8.9%) and 23F (23/6.8%). Analysis performed per years showed a higher prevalence of serotype 3 Streptococcus pneumoniae during the study period 2004 and 2005. During the entire study period (1999-2006) serotype 3 was most commonly isolated in children older than 24 months (61.2% vs 40.6%;P = 0.05) and showed a lower rate of penicillin non-susceptibility (4.0% vs 18%; P = 0.003).

CONCLUSION

Streptococcus pneumoniae serotype 3 is an important pathogen in Costa Rican children with otitis media, especially in children older than 24 months of age (P = 0.05). Most serotype 3 isolates were susceptible to penicillin, cephalosporins, macrolides and quinolones.

Introduction and proliferation of multidrug-resistant Streptococcus pneumoniae serotype 19A clones that cause acute otitis media in an unvaccinated population

BACKGROUND

Introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in the United States in 2000 was temporally associated with an increase in the incidence of disease caused by Streptococcus pneumoniae serotype 19A (Sp19A) and with increasing drug resistance within this serotype. A causative role of PCV7 was speculated. We prospectively studied the dynamics of acute otitis media (AOM) caused by Sp19A in southern Israel before the introduction of PCV7.

METHODS

AOM in children < 5 years old undergoing tympanocentesis during 1999-2006 was studied. Antibiotic prescriptions for approximately 20% of children < 5 years old were recorded. Sp19A isolates were studied for antibiotic-resistance and pulsed-field gel electrophoresis patterns; multilocus sequence typing of representative isolates was compared with that of international clones.

RESULTS

Sp19A caused 438 (9.8%) of 4449 pneumococcal AOM episodes, increasing by 63.1% from 1999-2001 (mean +/- SD, 8.4% +/- 0.8%) to 2004-2006 (mean +/- SD, 13.7% +/- 0.9%) among Bedouin children, who were characterized by overcrowding and high antibiotic use. Penicillin, erythromycin, and multidrug resistance increased from < 10% to 78.6%, 50.0%, and 50.0%, respectively (P < .001), and was associated with the introduction and proliferation of 2 multidrug-resistant clones that were not previously associated with multidrug resistance. This was temporally associated with the introduction of and rapid increase in azithromycin use and the frequent use of oral cephalosporins.

CONCLUSIONS

The introduction and proliferation of multidrug-resistant Sp19A occurred before the introduction of PCV7. The increasing proportion of antibiotic-resistant Sp19A suggests that antibiotic use plays an important role in the community.

Complicated community acquired pneumonia in children prior to the introduction of the pneumococcal conjugated vaccine

Increasing prevalence of pleural empyema (PE) complicating community acquired pneumonia (CAP) is reported worldwide. We compared hospitalized children with PE or non-purulent pleural effusion (NP-PEF) prior to the inclusion of the pneumococcal conjugated vaccine (PCV7) in the Israeli immunization schedule. We conducted a retrospective analysis of medical files of all children <18 y of age hospitalized with either PE or NP-PEF and CAP during 1990-2002. 75 children with NP-PEF and 37 with PE were identified. PE annual incidence increased from 0.5 in 1990 to 4.2 per 100,000 children in 2002. Higher WBC and absolute neutrophils counts were found in sera and pleural fluid of PE. The leading pathogens included Streptococcus pneumoniae (42%, all penicillin-susceptible) and Staphylococcus aureus (23%, all methicillin-susceptible). Blood cultures were positive only in children with PE (12/37, 32.4%). Patients with PE presented with higher respiratory rate and required longer hospitalization, more PICU admission, and more patients needed mechanical ventilation. PE prevalence increased in southern Israel during the study period. Streptococcus pneumoniae (62.5% serotype 1) was the most common pathogen causing PE before the introduction of PCV7. Future introduction of PCV7 or equivalents in the immunization schedule may impact clinical presentation and epidemic trends and will require future consideration.

Impact of 4% chlorhexidine whole-body washing on multidrug-resistant Acinetobacter baumannii skin colonisation among patients in a medical intensive care unit

The prevalence of skin colonisation with Acinetobacter baumannii (ACBA) on admission to the medical intensive care unit (MICU) was studied in an institution endemic for ACBA bloodstream infections (BSIs). The impact of 4% chlorhexidine gluconate (4% CG) whole-body washing on the patients' ACBA skin colonisation was also determined. A prospective cohort trial in a MICU during March 2002 to December 2003 was performed, with a comparison between the prevalence and incidence of ACBA-BSIs obtained after intervention and retrospectively. During the intervention period, ACBA skin-screening swabs were taken from all patients on admission and periodically until discharge. Patients underwent whole-body disinfection with 4% CG immediately after obtaining the initial cultures. Disinfection was carried out on a daily basis until discharge, regardless of colonisation status. Of the 320 patients at ward admission, 55 (17%) yielded ACBA. The prevalence of ACBA colonisation among the remaining MICU patients was 5.5% at 24h and 1% at 48h following the disinfection regimen (P=0.002, OR: 2.4). Following a second screen, 80% of colonised patients were decolonised. Prevalence of ACBA-BSIs decreased from 4.6 to 0.6 per 100 patients (P < or = 0.001; OR: 7.6) and incidence decreased from 7.8 to 1.25 (85% reduction). We conclude that daily whole-body disinfection with 4% CG significantly reduced ACBA skin colonisation. This regimen may be considered in addition to well-known infection control measures, particularly in institutions with endemic rates of multidrug-resistant ACBA-BSIs.

Effect of hydrogen peroxide production and the Fenton reaction on membrane composition of Streptococcus pneumoniae

As part of its aerobic metabolism, Streptococcus pneumoniae generates high levels of H(2)O(2) by pyruvate oxidase (SpxB), which can be further reduced to yield the damaging hydroxyl radicals via the Fenton reaction. A universal conserved adaptation response observed among bacteria is the adjustment of the membrane fatty acids to various growth conditions. The aim of the present study was to reveal the effect of endogenous reactive oxygen species (ROS) formation on membrane composition of S. pneumoniae. Blocking carbon aerobic metabolism, by growing the bacteria at anaerobic conditions or by the truncation of the spxB gene, resulted in a significant enhancement in fatty acid unsaturation, mainly cis-vaccenic acid. Moreover, reducing the level of OH(.) by growing the bacteria at acidic pH, or in the presence of an OH(.) scavenger (salicylate), resulted in increased fatty acid unsaturation, similar to that obtained under anaerobic conditions. RT-PCR results demonstrated that this change does not originate from a change in mRNA expression level of the fatty acid synthase II genes. We suggest that endogenous ROS play an important regulatory role in membrane adaptation, allowing the survival of this anaerobic organism at aerobic environments of the host.

Use of FTIR spectroscopy to distinguish between capsular types and capsular quantities in Streptococcus pneumoniae

Fourier transform infrared (FTIR) spectroscopy has shown remarkable ability in distinguishing between bacterial species and identifying bacterial colony structures, when used in tandem with methods such as cluster analysis, principal component analysis, or linear discriminant analysis. The present work was aimed to evaluate the potential of FTIR-microscopy (FTIR-MSP) to distinguish between different serotypes and capsular quantities of Streptococcus pneumoniae. In general, the results obtained have consistently proven that the spectral information at the region 900-1,185 cm(-1) was sufficient to distinguish between various pneumococcal serotypes. Moreover, the method was able to differentiate between S. pneumoniae phase variants on the basis of their relative carbohydrate content. The unsupervised cluster analysis of the samples showed differences, not only in the carbohydrate content, but also in the region 1,350-1,480 cm(-1), which is dominated by absorptions due to lipids and phospholipids. This approach proved to be useful for the distinction between S. pneumoniae serotypes and between phase variants, which were shown to acquire different pathogenic capacity.

The important role of nontypable Streptococcus pneumoniae international clones in acute conjunctivitis

BACKGROUND

In a recent epidemiological study in southern Israel, nontypable Streptococcus pneumoniae isolates were found to be highly associated with sporadic cases of acute conjunctivitis (AC). The purpose of the present study was to evaluate the relative importance in causing AC of the absence of capsule versus genotype properties.

METHODS

DNA typing by pulsed-field gel electrophoresis (PFGE) was performed on 148 nontypable organisms isolated from 3 sites: nasopharynx of healthy children, middle-ear fluid, and conjunctiva.

RESULTS

Analysis of the PFGE patterns revealed the presence of 6 clusters; 2 clusters that included 44% of the isolates (65/148) were associated with AC, and the remaining 4 were frequently isolated from the nasopharynx. Multilocus sequence typing, performed on representative isolates of the 2 major clusters, confirmed that the organisms were pneumococci; one is a single-locus variant of sequence type (ST) 448, and the other is related to ST344. Both types appear to be members of pneumococcal lineages that have lost capsular loci. The nontypable isolates showed high rates of resistance to antimicrobial agents.

CONCLUSIONS

Our data suggest that the absence of the capsule--along with other, yet-unidentified genetic characteristics--provide S. pneumoniae with a selective virulence advantage in conjunctivitis.

Site-specific disease potential of individual Streptococcus pneumoniae serotypes in pediatric invasive disease, acute otitis media and acute conjunctivitis

BACKGROUND

Recent studies have shown that some Streptococcus pneumoniae serotypes possess a higher potential to cause invasive disease than others. However, it is unknown whether disease potential for specific serotypes is similar for mucosal disease. Our objective was to assess the disease potential of individual S. pneumoniae serotypes causing invasive pneumococcal disease (IPD), acute otitis media (AOM) and acute conjunctivitis (AC) in children.

METHODS

Serotypes of pneumococcal isolates from children with IPD, AOM and AC were compared with those carried by healthy children aged <3 years. All children resided in the same area and were studied during the same period. Odds ratios for disease were calculated for each diagnosis following multivariate analysis, including gender, age, ethnic group, previous antibiotic treatment and year variability.

RESULTS

A total of 5,500 isolates were collected: 189 from blood or cerebrospinal fluid, 3,200 from middle ear fluid, 348 from conjunctiva and 1,763 from nasopharynx of healthy children. A significant positive association with IPD was demonstrated for serotypes 1, 5 and 12F; with AOM for serotypes 1, 3, 5, 12F, 19A and 19F; and with AC for serotype 3 and nontypeable S. pneumoniae. A significant negative association with IPD was demonstrated for nontypeable S. pneumoniae and with AOM for serotypes 6A, 6B, 15A and nontypeable S. pneumoniae.

CONCLUSIONS

Our results reflect the importance of the polysaccharide capsule in site-specific disease potential and provide useful information regarding disease potential of nonvaccine serotypes shown to be involved in carriage replacement after vaccination with the 7-valent conjugate vaccine.

Outbreak of Kingella kingae skeletal system infections in children in daycare

OBJECTIVE

The objective of this study is to describe the investigation of an outbreak of one culture-proven and two presumptive cases of Kingella kingae osteomyelitis detected within a 15-day period in a daycare center in Israel.

METHODS

Surveillance pharyngeal cultures were obtained from all attendees at the index daycare center and from two neighboring facilities. Combined amoxicillin-rifampin prophylaxis was administered to all children aged 6 to 30 months living in the community. K. kingae isolates were typed by pulsed field gel electrophoresis, random amplified polymorphic DNA analysis and sequencing of the rRNA genes.

RESULTS

Surveillance cultures showed that four of 11 attendees at the index facility as well as five of 12 and one of 15 attendees at neighboring daycare centers carried K. kingae. Typing of isolates showed that the isolate from a child with osteomyelitis was identical to all other isolates from the same daycare center and different from organisms derived from the other facilities. Administration of prophylactic antibiotics resulted in partial eradication of the organism.

CONCLUSIONS

Dissemination of K. kingae in a susceptible pediatric population may result in an outbreak of invasive disease. Our experience suggests the need for increased alertness for clusters of K. kingae infections among children in daycare.

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.

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.

Emergence of Penicillin‐NonsusceptibleStreptococcus pneumoniaeClones 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.

Lack of evidence of transmission of Pseudomonas aeruginosa among cystic fibrosis patients attending health camps at the Dead Sea, Israel

BACKGROUND

Transmission of Pseudomonas aeruginosa among cystic fibrosis patients attending health camps has been reported previously.

OBJECTIVES

To determine the transmission of P. aeruginosa among CF patients during three winter camps in the Dead Sea region in southern Israel.

METHODS

Three consecutive CF patient groups were studied, each of which spent 3 weeks at the camp. The patients were segragated prior to camp attendance: patients who were not colonized with P. aeruginosa constituted the first group, and colonized patients made up the two additional groups. Sputum cultures were obtained upon arrival, at mid-camp and on the last day. Environmental cultures were also obtained. Patients were separated during social activities and were requested to avoid social mingling. Isolates were analyzed by antibiotic susceptibility profile and by pulsed field gel electrophoresis.

RESULTS

Ninety isolates from 19 patients produced 28 different fingerprint patterns by PFGE. Isolates from two siblings and two patients from the same clinic displayed the same fingerprint pattern. These patients were already colonized with these organisms upon arrival. Two couples were formed during the camp, but PFGE showed no transmission of organisms. All other patients' isolates displayed unique fingerprint patterns and were distinguishable from those of other attendees, and none of the P. aeruginosa-negative patients acquired P. aeruginosa during camp attendance. Environmental cultures were negative for P. aeruginosa.

CONCLUSIONS

We were unable to demonstrate cross-infection of P. aeruginosa among CF patients participating in health camps at the Dead Sea who were meticulously segregated.

Differences in membrane fluidity and fatty acid composition between phenotypic variants of Streptococcus pneumoniae

Phase variation in the colonial opacity of Streptococcus pneumoniae has been implicated as a factor in the pathogenesis of pneumococcal disease. This study examined the relationship between membrane characteristics and colony morphology in a few selected opaque-transparent couples of S. pneumoniae strains carrying different capsular types. Membrane fluidity was determined on the basis of intermolecular excimerization of pyrene and fluorescence polarization of 1,6-diphenyl 1,3,5-hexatriene (DPH). A significant decrease, 16 to 26% (P < or = 0.05), in the excimerization rate constant of the opaque variants compared with that of the transparent variants was observed, indicating higher microviscosity of the membrane of bacterial cells in the opaque variants. Liposomes prepared from phospholipids of the opaque phenotype showed an even greater decrease, 27 to 38% (P < or = 0.05), in the pyrene excimerization rate constant compared with that of liposomes prepared from phospholipids of bacteria with the transparent phenotype. These findings agree with the results obtained with DPH fluorescence anisotropy, which showed a 9 to 21% increase (P < or = 0.001) in the opaque variants compared with the transparent variants. Membrane fatty acid composition, determined by gas chromatography, revealed that the two variants carry the same types of fatty acids but in different proportions. The trend of modification points to the presence of a lower degree of unsaturated fatty acids in the opaque variants compared with their transparent counterparts. The data presented here show a distinct correlation between phase variation and membrane fluidity in S. pneumoniae. The changes in membrane fluidity most probably stem from the observed differences in fatty acid composition.

Virulence ofStreptococcus pneumoniaemay be determined independently of capsular polysaccharide

Mice were inoculated intranasally with Streptococcus pneumoniae isolates of serotype 14 with different genetic backgrounds (14R, 14DW) and a capsular switch of 14R, strain 9VR (serotype 9V). Inoculation of the mice with 14R and 9VR resulted in 60% mortality. All the mice survived 14DW inoculation. No differences in lungs' bacterial loads were found 3 h following inoculation. Bacterial clearance of 5 logs was observed 48 h after inoculation with 14DW versus within 1 log 48 h after inoculation with 14R and 9VR. No significant differences in bacterial size or the capsular amount could be found between 14R and 14DW. We conclude that factor(s) in addition to the capsule, contribute to disease outcome.

Antibiotic-resistant invasive pediatric Streptococcus pneumoniae clones in Israel

Antibiotic-resistant international clones of Streptococcus pneumoniae are increasingly reported in different parts of the world. We investigated the spread of these clones through an active surveillance performed at the Israeli Streptococcal National Center during 1998 and 1999. Isolates were tested for antibiotic susceptibility, serotyped, and genotyped by random amplified polymorphic DNA analysis and pulsed-field gel electrophoresis. Of 437 isolates, 276 (63.4%) were antibiotic resistant and 156 (35%) were penicillin nonsusceptible (PNS). The PNS isolates were less frequently encountered in southern Israel (27 of 136 [20%]) than in other regions (127 of 301 [42%]). Among 276 antibiotic-resistant isolates, 43 fingerprint patterns were observed. The most common clones were 9V/14-a (19.2%), 5-a (17.8%), and 1-a (10%). The 9V/14-a clone was less common, while the 1-a clone was more frequent in the south than in other regions. The 5-a clone was more common in Jerusalem than in other regions. Among the Jewish and Arab populations the most frequent clones were 9V/14-a (20%) and 1-a (25%), respectively. Three international clones, 9V/14-a-Spain(9V)-3, 6B-a-Spain(6B)-2, and 5-a-Colombia(5)-19, comprised 40% of all antibiotic-resistant isolates and 56% of all PNS isolates. The seven-valent conjugate vaccine covers 58% of the most common clones, all highly PNS clones, and 94% of the multidrug-resistant clones in Israel, while the nine-valent vaccine covers all of them. The most common antibiotic-resistant invasive pediatric S. pneumoniae clones-mainly the three international ones-contribute significantly to increases in antibiotic resistance. Their geographic distribution varies within the country and between the different populations.

Nasopharyngeal carriage of Streptococcus pneumoniae by adults and children in community and family settings

The rate of Streptococcus pneumoniae carriage among adults was compared with that among children (age, < or =6 years) in the same population. Nasopharyngeal culture results for 1300 adults and 404 children were analyzed. S. pneumoniae was carried by only 4% of the adults, compared with 53% of children in the same community. Young age, day care center attendance, having young siblings, and no antibiotic use during the month before screening were associated with the high carriage rate among children, whereas the only risk factor associated with carriage among adults was the presence of a respiratory infection on the screening day. S. pneumoniae serotype distribution and antibiotic resistance patterns differed between adults and children. Isolates of the same serotype--even of the same clone--differed in their antibiotic susceptibility patterns between children and adults. In a subanalysis of 151 pairs of children and their parents and of 32 pairs of siblings, intrafamilial transmission of S. pneumoniae could not be demonstrated.