Representation of Streptococcus Pneumoniae in Outpatient Population of Sarajevo Canton

Introduction:

Streptococcus pneumoniae in asymptomatic manner colonize the mucous membranes of the nasopharynx of children and adults, but can cause serious illness in the media which are naturally sterile. In 5-40% of healthy population this bacteria colonize the nasopharyngeal mucosa thanks to the surface adhesin protein, which allow the bacteria to attach to the epithelial cells. The normal nasopharyngeal microflora retains pneumococcus in a small number and does not allow it to express its pathogenic potential and cause disease. If this dominance of the normal microflora is violated, after adherence and local duplication, pneumococcus can spread to the middle ear, sinuses or lungs. Colonization is more common in children than in adults.

Goal:

The goal of this study was to determine the prevalence of the carrier state and susceptibility of pneumococcal strains that circulate in the outpatient population of Sarajevo Canton as a potential source of infection.

Material and methods:

In the microbiological laboratory of the Institute of Public Health of Canton Sarajevo in the period from July 1, 2013 until April 15, 2014 were analyzed swabs of the nose and nasopharynx, eye and ear from a total of 4109 outpatients. Swabs were inoculated on blood agar nutrient medium. Then was performed catalase test, preparation by Gram and susceptibility test on Optochin. Isolates positive for S. pneumoniae were subjected to in vitro assays to investigate the antimicrobial susceptibility/resistance.

Results:

Out of 4109 analyzed swabs the pneumococcus positive was 180 (4.38%). Of these, 137 (76.11%) nasal and nasopharyngeal swabs, 33 (18.33%) of the eyes and 10 (5.56%) ear. The highest number of positive swabs were isolated in children aged 6 years and less, a total of 168 (93.33%), in children aged 7-13 years were positive 7 (3.89%), while among respondents aged 14-20 years only 5 (2.78%).

Conclusions:

The most common site for isolation of pneumococci is the nose and throat, and the most common carriers of these bacteria are children under 6 years of age. Determining the prevalence of the carrier state contributes to the improvement of preventive measures to reduce the risk of infection and possible sequels.

The Diversity of Meningococcal Carriage Across the African Meningitis Belt and the Impact of Vaccination With a Group A Meningococcal Conjugate Vaccine

Background. Study of meningococcal carriage is essential to understanding the epidemiology of Neisseria meningitidis infection.

Methods. Twenty cross-sectional carriage surveys were conducted in 7 countries in the African meningitis belt; 5 surveys were conducted after introduction of a new serogroup A meningococcal conjugate vaccine (MenAfriVac). Pharyngeal swab specimens were collected, and Neisseria species were identified by microbiological and molecular techniques.

Results. A total of 1687 of 48 490 participants (3.4%; 95% confidence interval [CI], 3.2%–3.6%) carried meningococci. Carriage was more frequent in individuals aged 5–14 years, relative to those aged 15–29 years (adjusted odds ratio [OR], 1.41; 95% CI, 1.25–1.60); in males, relative to females (adjusted OR, 1.17; 95% CI, 1.10–1.24); in individuals in rural areas, relative to those in urban areas (adjusted OR, 1.44; 95% CI, 1.28–1.63); and in the dry season, relative to the rainy season (adjusted OR, 1.54; 95% CI, 1.37–1.75). Forty-eight percent of isolates had genes encoding disease-associated polysaccharide capsules; genogroup W predominated, and genogroup A was rare. Strain diversity was lower in countries in the center of the meningitis belt than in Senegal or Ethiopia. The prevalence of genogroup A fell from 0.7% to 0.02% in Chad following mass vaccination with MenAfriVac.

Conclusions. The prevalence of meningococcal carriage in the African meningitis belt is lower than in industrialized countries and is very diverse and dynamic, even in the absence of vaccination.

Colonization with Enterobacteriaceae producing ESBLs in children attending pre-school childcare facilities in the Lao People's Democratic Republic

Objectives

Intestinal carriage constitutes an important reservoir of antimicrobial-resistant bacteria, with some of the highest rates reported from Asia. Antibiotic resistance has been little studied in Laos, where some antibiotics are available without restriction, but others such as carbapenems are not available.

Patients and methods

We collected stools from 397 healthy children in 12 randomly selected pre-school childcare facilities in and around Vientiane. Colonization with ESBL-producing Enterobacteriaceae (ESBLE) and carbapenemase-producing Enterobacteriaceae (CPE) was detected using a disc diffusion screening test and ESBLE were characterized using WGS. Risk factor data were collected by questionnaire.

Results

Ninety-two children (23%) were colonized with ESBLE, mainly Escherichia coli carrying bla_CTX-M and Klebsiella pneumoniae carrying bla_SHV or bla_CTX-M, which were frequently resistant to multiple antibiotic classes. Although residence in Vientiane Capital, foreign travel, higher maternal level of education, antibiotic use in the preceding 3 months and attending a childcare facility with a ‘good’ level of hygiene were all associated with ESBLE colonization on univariable analysis, a significant association remained only for antibiotic use when a stepwise approach was used with a multivariate random-effects model. WGS analysis suggested transmission in both childcare facilities and community settings.

Conclusions

The high prevalence of paediatric colonization with ESBLE in Laos, one of the highest reported in Asia, is probably the result of inappropriate antibiotic use. Paediatric colonization with CPE was not identified in this study, but it is important to continue to monitor the spread of antibiotic-resistant Enterobacteriaceae in Laos.

Multicentre evaluation of the Check-Direct CPE® assay for direct screening of carbapenemase-producing Enterobacteriaceae from rectal swabs

OBJECTIVES

The objective of this study was to evaluate in a multicentre survey the analytical performance of the Check-Direct CPE® assay (CDCPE), a multiplex PCR assay for the detection of carbapenemase-producing Enterobacteriaceae (CPE), directly from rectal swabs.

METHODS

Adult patients admitted to a high-risk unit in four participating centres were prospectively screened for CPE carriage by rectal swabbing. Samples were cultured on chromogenic CPE-selective media in the local laboratories. All growing Enterobacteriaceae strains were transferred for confirmation of carbapenemase production by multiplex PCR, together with the faecal swabs for CDCPE, to the coordinating laboratory.

RESULTS

Overall, 38 of the 394 samples analysed (9.6%; range 3%-20% per centre) yielded a positive signal for a carbapenemase gene with CDCPE, including 17 samples (4.3%; range 0%-15% per centre) that grew a total of 25 CPE-confirmed isolates (all OXA-48-like producers, including one isolate that simultaneously harboured a VIM-type carbapenemase). No CPE culture-positive samples were missed by CDCPE. Among the 21 samples that were CPE-positive with CDCPE but negative on culture, five were collected from previously known CPE carriers and 6/9 OXA-48-positive signals were detected at one participating centre that was undergoing a hospital-wide outbreak of OXA-48 CPE. When compared with the selective culture, the sensitivity and specificity of CDCPE were 100% and 94%, respectively.

CONCLUSIONS

This study showed the value of CDCPE as a tool for screening CPE carriage in an epidemiological setting with a high prevalence of OXA-48 CPE. However, the potential added value for infection control management remains to be demonstrated.

Persistent low carriage of serogroup A Neisseria meningitidis two years after mass vaccination with the meningococcal conjugate vaccine, MenAfriVac

BACKGROUND

The conjugate vaccine against serogroup A Neisseria meningitidis (NmA), MenAfriVac, is currently being introduced throughout the African meningitis belt. In repeated multicentre cross-sectional studies in Burkina Faso we demonstrated a significant effect of vaccination on NmA carriage for one year following mass vaccination in 2010. A new multicentre carriage study was performed in October-November 2012, two years after MenAfriVac mass vaccination.

METHODS

Oropharyngeal samples were collected and analysed for presence of N. meningitidis (Nm) from a representative selection of 1-29-year-olds in three districts in Burkina Faso using the same procedures as in previous years. Characterization of Nm isolates included serogrouping, multilocus sequence typing, and porA and fetA sequencing. A small sample of invasive isolates collected during the epidemic season of 2012 through the national surveillance system were also analysed.

RESULTS

From a total of 4964 oropharyngeal samples, overall meningococcal carriage prevalence was 7.86%. NmA prevalence was 0.02% (1 carrier), significantly lower (OR, 0.05, P = 0.005, 95% CI, 0.006-0.403) than pre-vaccination prevalence (0.39%). The single NmA isolate was sequence type (ST)-7, P1.20,9;F3-1, a clone last identified in Burkina Faso in 2003. Nm serogroup W (NmW) dominated with a carriage prevalence of 6.85%, representing 87.2% of the isolates. Of 161 NmW isolates characterized by molecular techniques, 94% belonged to the ST-11 clonal complex and 6% to the ST-175 complex. Nm serogroup X (NmX) was carried by 0.60% of the participants and ST-181 accounted for 97% of the NmX isolates. Carriage prevalence of serogroup Y and non-groupable Nm was 0.20% and 0.18%, respectively. Among the 20 isolates recovered from meningitis cases, NmW dominated (70%), followed by NmX (25%). ST-2859, the only ST with a serogroup A capsule found in Burkina Faso since 2004, was not found with another capsule, neither among carriage nor invasive isolates.

CONCLUSIONS

The significant reduction of NmA carriage still persisted two years following MenAfriVac vaccination, and no cases of NmA meningitis were recorded. High carriage prevalence of NmW ST-11 was consistent with the many cases of NmW meningitis in the epidemic season of 2012 and the high proportion of NmW ST-11 among the characterized invasive isolates.

Methicillin-resistant Staphylococcus aureus carriage among veterinary staff and dogs in private veterinary clinics in Hokkaido, Japan

To explore the prevalence and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) in veterinary medical practices, MRSA carriage was tested among 96 veterinarians (Vets), 70 veterinary technicians (VTs) and 292 dogs with which they had contact at 71 private veterinary clinics (VCs) in Hokkaido, Japan. MRSA isolates were obtained from 22 Vets [22.9%] and 7 VTs [10%]. The prevalence of MRSA among Vets was as high as that found in an academic veterinary hospital in our previous study. In contrast, only two blood donor dogs and one dog with liver disease (1.0%, 3/292) yielded MRSA. All MRSA-positive dogs were reared or treated in different VCs, in each of which at least one veterinary staff member carrying MRSA worked. Sequence types (ST) identified by multilocus sequence typing, spa types, and SCCmec types for canine MRSA isolates (ST5-spa t002-SCCmec II [from two dogs] or ST30-spa t021-SCCmec IV [from a dog]) were concordant with those from veterinary staff members in the same clinics as the MRSA-positive dogs, with which they had potentially had contact. Most MRSA isolates from veterinary staff were the same genotype (SCCmec type II and spa type t002) as a major hospital-acquired MRSA clone in Japan. The remaining MRSA was the same genotypes as domestic and foreign community-associated MRSA. Measures against MRSA infection should be provided in private VCs.

Impact of the Hajj on pneumococcal transmission

Over two million Muslim pilgrims assemble annually in Mecca and Medina, Saudi Arabia, to complete the Hajj. The large number of people in a crowded environment increases the potential for pneumococcal carriage amplification. We evaluated pneumococcal carriage prevalence with four cross-sectional studies conducted at beginning-Hajj (Mecca) and end-Hajj (Mina) during 2011 and 2012. A questionnaire was administered and a nasopharyngeal swab was collected. The swab was tested for pneumococcus, serotype and antibiotic resistance. A total of 3203 subjects (1590 at beginning-Hajj and 1613 at end-Hajj) originating from 18 countries in Africa or Asia were enrolled. The overall pneumococcal carriage prevalence was 6.0%. There was an increase in carriage between beginning-Hajj and end-Hajj cohorts for: overall carriage (4.4% versus 7.5%, prevalence ratio (PR) 1.7, 95% CI 1.3-2.3), and carriage of 23-valent pneumococcal polysaccharide vaccine serotypes (2.3% versus 4.1%, PR 1.8, 95% CI 1.2-2.7), 13-valent pneumococcal conjugate vaccine (PCV) serotypes (1.1% versus 3.6%, PR 3.2, 95% CI 1.9-5.6), 10-valent PCV serotypes (0.6% versus 1.6%, PR 2.6, 95% CI 1.2-5.3), antibiotic non-susceptible isolates (2.5% versus 6.1%, PR 2.5, 95% CI 1.7-3.6) and multiple non-susceptible isolates (0.6% versus 2.2%, PR 3.8, 95% CI 1.8-7.9). Fifty-two different serotypes were identified, most commonly serotypes 3 (17%), 19F (5%) and 34 (5%). These results suggest that the Hajj may increase pneumococcal carriage-particularly conjugate vaccine serotypes and antibiotic non-susceptible strains, although the exact mechanism remains unknown. The Hajj may therefore provide a mechanism for the global distribution of pneumococci.

Extended-spectrum and AmpC β-lactamase-producing Escherichia coli in broilers and people living and/or working on broiler farms: prevalence, risk factors and molecular characteristics

OBJECTIVES

The objectives of this study were to: estimate the prevalence of extended-spectrum β-lactamase (ESBL)- and AmpC β-lactamase-producing Escherichia coli carriage among broiler farmers, their family members and employees; identify and quantify risk factors for carriage, with an emphasis on contact with live broilers; and compare isolates from humans and broilers within farms with respect to molecular characteristics to gain insight into transmission routes.

METHODS

A cross-sectional prevalence study was conducted on 50 randomly selected Dutch broiler farms. Cloacal swabs were taken from 20 randomly chosen broilers. Faecal swabs were returned by 141 individuals living and/or working on 47 farms. ESBL/AmpC-producing E. coli were isolated and, for selected isolates, phylogenetic groups, plasmids and sequence types were determined. Questionnaires were used for risk factor analysis.

RESULTS

All sampled farms were positive, with 96.4% positive pooled broiler samples. The human prevalence was 19.1%, with 14.3% and 27.1% among individuals having a low and a high degree of contact with live broilers, respectively. Five pairs of human-broiler isolates had identical genes, plasmid families and E. coli sequence types, showing clonal transmission. Furthermore, similar ESBL/AmpC genes on the same plasmid families in different E. coli sequence types in humans and broilers hinted at horizontal gene transfer.

CONCLUSIONS

The prevalence among people on broiler farms was higher than in previous studies involving patients and the general population. Furthermore, an increased risk of carriage was shown among individuals having a high degree of contact with live broilers. The (relative) contribution of transmission routes that might play a role in the dissemination of ESBL/AmpC-encoding resistance genes to humans on broiler farms should be pursued in future studies.

Outbreaks of Kingella kingae infections in daycare facilities

During the past decade, transmission of the bacterium Kingella kingae has caused clusters of serious infections, including osteomyelitis, septic arthritis, bacteremia, endocarditis, and meningitis, among children in daycare centers in the United States, France, and Israel. These events have been characterized by high attack rates of disease and prevalence of the invasive strain among asymptomatic classmates of the respective index patients, suggesting that the causative organisms benefitted from enhanced colonization fitness, high transmissibility, and high virulence. After prophylactic antibacterial drugs were administered to close contacts of infected children, no further cases of disease were detected in the facilities, although test results showed that some children still carried the bacterium. Increased awareness of this public health problem and use of improved culture methods and sensitive nucleic acid amplification assays for detecting infected children and respiratory carriers are needed to identify and adequately investigate outbreaks of K. kingae disease.

Duration of shedding of Verocytotoxin-producing Escherichia coli in children and risk of transmission in childcare facilities in England

Exclusion of children with presumptive Verocytotoxin-producing Escherichia coli (VTEC) from childcare facilities until negative stool specimens are obtained is routine practice that disrupts families. We estimated the shedding and exclusion duration and transmission risk in such facilities. The study population comprised 225 children aged <6 years attending 201 childcare facilities in England with microbiologically confirmed VTEC in 2010-2011. We estimated the interval from onset to first negative specimen, and identified transmission events with secondary cases linked to facilities. The median duration of shedding was 31 days, and median period of exclusion was 39·5 days. Cases attending facilities while shedding VTEC did so for a median of 2 days before exclusion. Secondary cases occurred in 6/83 facilities (7%) attended by infectious cases. Despite evidence of VTEC shedding at facilities, transmission is relatively low. Revised control guidelines could consider supervised return for prolonged asymptomatic shedders.

The impact of specific and non-specific immunity on the ecology of Streptococcus pneumoniae and the implications for vaccination

More than 90 capsular serotypes of Streptococcus pneumoniae coexist despite competing for nasopharyngeal carriage and a gradient in fitness. The underlying mechanisms for this are poorly understood and make assessment of the likely population impact of vaccination challenging. We use an individual-based simulation model to generalize widely used deterministic models for pneumococcal competition and show that in these models short-term serotype-specific and serotype non-specific immunity could constitute the mechanism governing between-host competition and coexistence. We find that non-specific immunity induces between-host competition and that serotype-specific immunity limits a type's competitive advantage and allows stable coexistence of multiple serotypes. Serotypes carried at low prevalence show high variance in carriage levels, which would result in apparent outbreaks if they were highly pathogenic. Vaccination against few serotypes can lead to elimination of the vaccine types and induces replacement by others. However, in simulations where the elimination of the targeted types is achieved only by a combination of vaccine effects and the competitive pressure of the non-vaccine types, a universal vaccine with similar-type-specific effectiveness can fail to eliminate pneumococcal carriage and offers limited herd immunity. Hence, if vaccine effects are insufficient to control the majority of serotypes at the same time, then exploiting the competitive pressure by selective vaccination can help control the most pathogenic serotypes.

Using pneumococcal carriage data to monitor postvaccination changes in invasive disease

Pneumococcal conjugate vaccines (PCVs) have been introduced worldwide. However, few developing countries have high-quality surveillance systems available for monitoring vaccine impact. We evaluated whether data from nasopharyngeal carriage studies can be used to accurately monitor post-PCV changes in the incidence of invasive pneumococcal disease (IPD) among children under 5 years of age. For various dates during 1991-2010, data on nasopharyngeal pneumococcal carriage and on IPD before and after administration of 7-valent PCV (PCV7) were available from England and Wales, the Netherlands, the Navajo and White Mountain Apache American Indian populations, and the US states of Massachusetts and Alaska. We estimated the change in carriage prevalence for each serotype in each study and then either calculated the average change (inverse variance-weighted) among vaccine and nonvaccine serotypes (model 1) or used mixed-effects models to estimate the change for each serotype individually, pooling serotype data within or between studies (models 2 and 3). We then multiplied these values by the proportion of IPD caused by each serotype during the pre-PCV7 period to obtain an estimate of post-PCV7 disease incidence. Model 1 accurately captured overall changes in IPD incidence following PCV7 introduction for most studies, while the more detailed models, models 2 and 3, were less accurate. Carriage data can be used in this simple model to estimate post-PCV changes in IPD incidence.

Routine vaccination against MenB: considerations for implementation

Effective polysaccharide(conjugate) vaccines against Neisseria meningitidis serogroups A, C, W, and Y have been widely used, but serogroup B meningococci remain a major cause of severe invasive meningococcal disease (IMD) worldwide, especially in infants. Recently, a vaccine, 4CMenB (Bexsero^®), containing three recombinant proteins, and outer membrane vesicles (OMV) derived from a serogroup B meningococcal strain (MenB) has been licensed in Europe and Australia and is indicated for persons aged 2 mo or older. This article discusses what should be considered to enable a successful implementation of a broad coverage MenB vaccine in national immunization programs. Epidemiology data, vaccine characteristics including vaccine coverage, immunogenicity, post-implementation surveillance and costs are relevant aspects that should be taken into account when selecting an appropriate immunization strategy. The potential impact on strain variation and carriage, as well as monitoring vaccine effectiveness, and rare but potentially serious adverse events are points that need to be included in a post-implementation surveillance plan.

High genetic diversity of methicillin-susceptible Staphylococcus aureus (MSSA) from humans and animals on livestock farms and presence of SCCmec remnant DNA in MSSA CC398

OBJECTIVES

To investigate the genetic diversity of methicillin-susceptible Staphylococcus aureus (MSSA) carriage isolates from animals and humans on pig, veal, dairy, beef and broiler farms.

METHODS

S. aureus isolates were genotyped using spa typing and multilocus sequence typing (MLST). Antimicrobial susceptibility phenotypes and genotypes were determined. The presence of staphylococcal cassette chromosome mec (SCCmec)-associated DNA was characterized by PCR and sequencing among isolates of clonal complex (CC) 398.

RESULTS

Overall, 41 MSSA isolates in humans and 141 in animals were found, originating from all farm types. These MSSA were mainly assigned to CC398, CC1, CC5, CC9, CC30, CC97, CC133 and CC705/151. MSSA CC398 showed resistance to tetracycline, trimethoprim, macrolides and/or lincosamides, aminoglycosides, ciprofloxacin, spectinomycin and quinupristin/dalfopristin, whereas non-CC398 MSSA showed considerably less resistance. Three porcine MSSA CC398-t011 isolates harboured remnant DNA of a composite SCCmec V(5C2&5)c element that lacked the mec gene complex. This resulted from an MRSA-to-MSSA conversion due to recombination between the ccrC genes flanking the mec gene complex. The SCC remnant still contained an intact J1 region harbouring czrC and tet(K), encoding zinc and tetracycline resistance, respectively, thereby illustrating the capacity of S. aureus CC398 to adapt to different antibiotic selection pressures in the farming environment. Processes such as mec gene complex deletion probably contribute to the enormous diversity of SCC(mec) elements observed in staphylococci.

CONCLUSIONS

MSSA CC398 precursors from which MRSA CC398 might (re)emerge were present on pig, veal and broiler farms, all of which are livestock sectors commonly known to be affected by MRSA CC398. The multiresistance phenotype of S. aureus CC398 appears to be independent of methicillin resistance.

Surveillance of pneumococcal serotype 1 carriage during an outbreak of serotype 1 invasive pneumococcal disease in central Australia 2010-2012

BACKGROUND

An outbreak of serotype 1 invasive pneumococcal disease (IPD) occurred in Central Australia from October 2010 to the latter part of 2012. Surveillance of serotype 1 carriage was conducted to determine epidemiological features of asymptomatic carriage that could potentially be driving the outbreak.

METHODS

130 patients and accompanying persons presenting at Alice Springs Hospital Emergency Department consented to nasopharyngeal swab (NPS) collection. NPS were processed by standard methods, including culture, pneumococcal lytA quantitative real-time PCR, serotype 1-specific real-time PCR and multi-locus sequence typing (MLST).

RESULTS

Pneumococcal carriage was detected in 16% of participants. Carriage was highest in the under 10 year olds from remote communities surrounding Alice Springs (75%). Four NPS were positive for serotype 1 DNA by PCR; 3 were also culture-positive for serotype 1 pneumococci. Serotype 1 isolates had atypical colony morphology on primary culture. All serotype 1 carriers were healthy children 5 to 8 years of age from remote communities. By MLST, serotype 1 isolates were ST306, as were IPD isolates associated with this outbreak.

CONCLUSIONS

During an outbreak of serotype 1 ST306 IPD, carriage of the outbreak strain was detected in 3% NPS collected. All carriers were healthy children 5 to 8 years of age.

Live attenuated influenza vaccine, but not pneumococcal conjugate vaccine, protects against increased density and duration of pneumococcal carriage after influenza infection in pneumococcal colonized mice

Secondary bacterial infections due to Streptococcus pneumoniae and Staphylococcus aureus, responsible for excess morbidity and mortality during influenza epidemics, are often preceded by excess bacterial density within the upper respiratory tract. Influenza and pneumococcal vaccines reduce secondary infections within the lungs; however, their effects on upper respiratory tract carriage remain unknown. We demonstrate that a live attenuated influenza vaccine significantly reduces pneumococcal growth and duration of carriage during subsequent influenza to levels seen in influenza-naive controls. No benefit was seen after pneumococcal conjugate vaccine. Our results suggest that live attenuated influenza vaccines may significantly reduce bacterial disease during influenza epidemics.

Causes, consequences, and perspectives in the variations of intestinal density of colonization of multidrug-resistant enterobacteria

The intestinal microbiota is a complex environment that hosts 10¹³ to 10¹⁴ bacteria. Among these bacteria stand multidrug-resistant enterobacteria (MDRE), which intestinal densities can substantially vary, especially according to antibiotic exposure. The intestinal density of MDRE and their relative abundance (i.e., the proportion between the density of MDRE and the density of total enterobacteria) could play a major role in the infection process or patient-to-patient transmission. This review discusses the recent advances in understanding (i) what causes variations in the density or relative abundance of intestinal colonization, (ii) what are the clinical consequences of these variations, and (iii) what are the perspectives for maintaining these markers at low levels.

Patient nostril microbial flora: individual-dependency and diversity precluding prediction of Staphylococcus aureus acquisition

The potential role of a patient's resident microbial flora in the risk of acquiring multiresistant bacteria (MRB) during hospitalization is unclear. We investigated this role by cross-sectional study of 103 patients at risk of acquisition of Staphylococcus aureus (SA), resistant (MRSA) or not (MSSA) to methicillin, recruited in four French hospitals. The flora was analysed by an exhaustive culture-based approach combined with molecular and/or mass-spectrometry-based identification, and SA strain typing. Forty-three of the 53 SA-negative patients at entry were followed for up to 52 weeks: 19 (44.2%) remained negative for SA and 24 (55.8%) became positive, including 19 (79%) who acquired an MSSA, four (17%) who acquired an MRSA and one who acquired both (4%). Fifty-one different species were identified among the 103 patients, of which two, Corynebacterium accolens and Staphylococcus haemolyticus (p = 0.02-0.01), were more prevalent in the absence of SA. However, the same number of patients carrying or not these two species acquired an MSSA/MRSA during follow-up, regardless of antibiotic treatment received. Clustering analysis showed that the microbial flora was highly specific to each patient, and not predictive for acquisition of MSSA/MRSA or not. Patient-specific microbial resident flora is not predictive of SA acquisition.

Understanding the pneumococcus: transmission and evolution

Streptococcus pneumoniae is part of the normal bacterial flora of the narsopharynx, but is also associated with several invasive and non-invasive diseases. Recently, there has been a plethora of research information on the pneumococcus, however, there are few comprehensive review papers discussing the research information. This paper provides a review of the pneumococcus in two vital areas related to its biology including transmission and evolution. Transmission of the pneumococcus is a highly efficient process that usually occurs through respiratory droplets from asymptomatic carriers. Following acquisition, the pneumococcus may only establish in the nasopharynx of the new host, or further progress to sites such as the lungs and cause disease. Pneumococcus transmission risk factors, as well as factors involved in its translocation from the nasophyarnx to diseases sites are still not fully understood. Pneumococcal evolution is dominated by recombination. The recombinational events usually involve genetic exchange with streptococci of the mitis group and some pneumococci are thought to exhibit hyper-recombination.

Carriage of Streptoccoccus pneumoniae in healthy adults aged 60 years or over in a population with very high and long-lasting pneumococcal conjugate vaccine coverage in children: rationale and perspectives for PCV13 implementation

A serial cross-sectional study of nasopharyngeal carriage among adults aged 60 y or over was conducted in winter-spring 2012 with the aim to describe circulating Streptococcus pneumoniae in an area, Liguria Administrative Region, where the vaccine was implemented for a decade and coverage in pediatric age group reached a value close to 100% for more than 5 y, determining a picture of very high vaccine immunological pressure. The serotype-specific carriage picture in adults was compared with that observed in children by means of a cross-sectional study performed one year before using the same sampling and laboratory methods.   Cluster sampling enrolled 283 adults, representative of the open population. Detection of multi-serotype carriage was performed using, real-time PCR and primer specific PCRs. Carriage prevalence of participants with at least one positive sample adjusted for age, i.e., period prevalence, was 18.7%, considering the Ligurian population as standard population, showing that the pneumococcal carriage in the elderly is not a rare event as emerged in other surveys. The long-term use of PCV7 has resulted in strong decrease of vaccine types carriage among adults and children. A multivariate analysis showed that age class and contact with children attending day care covariates were strongly associated with Streptococcus pneumoniae carriage. A strong link between the picture observed in < 5-y-old children and ≥ 60-y-old adults emerged: a strong correlation of specific-serotype prevalence between adults and children and risk factor analysis supported the role played by inter-age-group transmission.

Carriage rates and serogroups of Neisseria meningitidis among freshmen in a University dormitory in Korea

PURPOSE

Neisseria meningitidis is a leading cause of bacterial meningitis in young adults. University students, especially those living in dormitories, have been known to be at increased risk of meningococcal disease. We performed a longitudinal study to determine the carriage rates of N. meningitidis and the changes thereof.

MATERIALS AND METHODS

We recruited Inha University freshmen who were, at that time, admitted to a student dormitory. A pharyngeal swab was taken from all participant who were also asked to complete a questionnaire. This was repeated four weeks later.

RESULTS

A total of 136 students were enrolled at the first culture. After four weeks, 128 students were enrolled, including 106 re-participants. The overall carriage rates changed from 11.8% to 14.1%. In analysis of the 106 re-participants, "visiting to pubs" was associated with carriage of N. meningitis for both the first (p=0.047) and second cultures (p=0.026). Serogroup C was found to be the most frequent serogroup (5 isolates), while 3 isolates were found from serogroup B. The most prevalent PorA types were P1.22,14-6 (4 isolates) and P1.19,15 (3 isolates). The DNA sequences of PorA VR2 were changed in 2 students during prolonged carriage.

CONCLUSION

The meningococcal carriage rate among first year university students who resided in a dormitory did not significantly increase over 4-week interval between cultures, which is markedly different from those reported in Western studies. Close social contact appeared to be related with carriage. Our data also revealed diversity in PorA types, suggesting the possibility of rapid mutation of the PorA gene during the 4-week interval.

Carriage of methicillin-resistant Staphylococcus pseudintermedius in dogs--a longitudinal study

BACKGROUND

Methicillin-resistant S. pseudintermedius strains (MRSP) are reported with increasing frequency in bacterial cultures from dogs. The objectives of this study were to determine whether MRSP could be found in dogs several months after a clinically apparent infection and whether the length of carriage varied depending on systemic antimicrobial treatment, diagnosis at time of the first positive MRSP culture and the presence of skin disease or wounds. Thirty-one dogs previously diagnosed with a clinical infection were sampled repeatedly for a minimum of eight months or, with the exception of two dogs, until two consecutive negative results were obtained. Five specified locations were sampled, and the results were evaluated to determine future recommendations concerning sample strategies when screening for MRSP carriage. Information was collected from medical records and questionnaires to evaluate factors that may influence length of carriage.

RESULTS

The overall median length of MRSP carriage was 11 months (48 weeks). The presence of wounds and signs of dermatitis did not influence length of carriage. Systemic treatment for three weeks or longer with antimicrobial agents to which the bacterium was resistant was associated with prolonged carriage compared to dogs treated for a shorter period of time. Three of five dogs treated with an antimicrobial to which their MRSP-isolates were susceptible (tetracycline) were found to still be MRSP-positive when sampled after the end of treatment. Wound samples had the highest positive MRSP yield (81%) for the positive sample sites, compared to less than 70% for each of the other four sample sites. Cultures from the nostrils were less likely to detect MRSP carriage relative to the pharynx, perineum, wounds and the corner of the mouth.

CONCLUSIONS

Dogs can carry MRSP for more than a year after a clinically apparent infection. Systemic antimicrobial treatment of infections with antimicrobial agents to which the MRSP-bacteria are resistant should be avoided when possible in dogs with possible or confirmed MRSP carriage or infection, since it may prolong time of MRSP carriage. Simultaneous sampling of pharynx, perineum, and the corner of the mouth as well as wounds when present is recommended when screening for MRSP. Cultures from nostrils were shown to be less likely to detect MRSP carriage.

The immune response to pneumococcal proteins during experimental human carriage

Colonization of the nasopharynx is the initial step in all infections caused by Streptococcus pneumoniae. The antibody response to carriage was examined in an experimental model of human colonization in healthy adults. Asymptomatic colonization was detected in 6/14 subjects and continued for up to 122 d. Susceptibility to carriage did not correlate with total serum immunoglobulin (Ig)G to the homotypic capsular polysaccharide. All of the colonized subjects, in contrast, developed a serum IgG and secretory IgA response to a 22 kD protein, whereas 7 of 8 subjects who did not become colonized had preexisting antibody to this protein. Analysis of the 22 kD protein identified it as the NH(2)-terminal region of pneumococcal surface protein A (PspA). Our findings provide evidence for the role of antibody to this protein fragment in preventing pneumococcal carriage by humans.