Emerging experience with meningococcal serogroup B protein vaccines

INTRODUCTION

The successful development of two broadly protective vaccines targeting Neisseria meningitidis serogroup B (MenB); 4CMenB and rLP2086, is the most significant recent advance in meningococcal disease prevention. Areas covered: Here we review the principles underlying the development of each vaccine and the novel methods used to estimate vaccine coverage. We update clinical and post-licensure experience with 4CMenB and rLP2086. Expert commentary: The immunogenicity and acceptable safety profile of 4CMenB and rLP2086 has been demonstrated in clinical trials. Continuing uncertainties exist around the appropriate age groups to be immunized, the degree and duration of efficacy, and the impact on nasopharyngeal carriage which has implications for strategies to interrupt transmission and maximize herd protection effects. Universal vaccination programs such as those undertaken in Quebec and the United Kingdom are providing important information on these issues. The potential for MenB vaccines to prevent infection by other serogroups appears promising, and the impact of MenB vaccines on other pathogenic neisserial species with similar surface proteins warrants further investigation.

Multidrug-Resistant Pathogens in Hospitalized Syrian Children

Since 2013, wounded and ill children from Syria have received treatment in Israel. Screening cultures indicated that multidrug-resistant (MDR) pathogens colonized 89 (83%) of 107 children. For 58% of MDR infections, the pathogen was similar to that identified during screening. MDR screening of these children is valuable for purposes of isolation and treatment.

Intense pre-admission carriage and further acquisition of ESBL-producing Enterobacteriaceae among patients and their caregivers in a tertiary hospital in Rwanda

OBJECTIVES

To assess the presence and risk factors of intestinal carriage of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) among patients admitted to the University Teaching Hospital of Butare and among their attending caregivers, and to analyse the acquisition of ESBL-PE carriage during hospital stay and associated factors.

METHODS

We screened 392 patients and their attending caregivers at admission and discharge for ESBL-PE carriage. Bacterial species were determined using the API-20E system, and antimicrobial susceptibility testing was performed by agar disc diffusion. Data on socio-economic status, diet, behaviour, household assets, livestock and hospital procedures were collected.

RESULTS

At admission, 50% of the patients showed intestinal ESBL-PE carriage (Escherichia coli, 51%; Klebsiella pneumoniae, 39%; Enterobacter cloacae, 19%) as did 37% of their caregivers. Co-resistance was common but no carbapenem resistance was detected. At discharge, the proportion of ESBL-PE-colonised patients increased to 65% (caregivers, 47%) with almost complete carriage in paediatric patients (93%). The acquisition rate among initially non-colonised patients was 55% (or, 71/1000 patient days). Independent predictors of admission carriage included a colonised caregiver, prior antibiotic intake, egg consumption and neglecting to boil drinking water, whereas being a paediatric patient, undergoing surgery and male gender predicted acquisition during hospitalisation.

CONCLUSIONS

Abundant admission carriage of ESBL-PE and a high acquisition rate in a Rwandan university hospital point to potential intrahospital transmission and community dissemination. Caregivers are an additional source of possible spread. Risk factors of colonisation such as diet and water source need to be tackled to prevent the further emergence and spread of ESBL-PE.

Screening of ESBL-producing Enterobacteriacae concomitant with low degree of transmission in intensive care and bone marrow transplant units

BACKGROUND

Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) are spreading worldwide in both hospital and community settings. In this study, the molecular epidemiology and the transmission modalities of ESBL-E in intensive care- and bone marrow transplant were investigated.

METHODS

All patients included in this study were screened for presence of ESBL-E on admission and weekly. Relevant β-lactamase genes were identified by PCR and sequencing.

RESULTS

A total of 669 patients were included in this study. On admission, ESBL-producing Escherichia coli were detected in 49 (7.3%) patients and ESBL-producing Klebsiella pneumoniae in one patient. The most common ESBL types among E. coli isolates were CTX-M-15 (38.8%) and CTX-M-1 (38.8%). Furthermore, 12 of 49 (24.5%) ESBL-producing E. coli could be assigned to the epidemic clone ST131. A single patient acquired ESBL-producing E. coli during the hospital stay but cross-transmission could not be demonstrated. Among 1095 environmental samples none revealed ESBL.

CONCLUSIONS

Our results suggest that early detection of ESBL-producing Enterobacteriaceae and consequent implementation of basic hygiene measures and contact isolation may reduce the transmission rate during the hospital stay.

Pneumococcal Colonization in the Familial Context and Implications for Anti-Pneumococcal Immunization in Adults: Results from the BINOCOLO Project in Sicily

The spread of Streptococcus pneumoniae within families has been scarcely investigated so far. This feasibility study aimed to estimate the prevalence of pneumococcal carriage in school-aged children and co-habiting relatives and to explore the potential link between the family environment and the sharing of pneumococcal serotypes covered by the vaccine. Oropharyngeal samples of 146 subjects belonging to 36 different family groups were molecularly tested for pneumococcal detection and serotyping. The overall prevalence of pneumococcal carriage was 65.8% (n = 96/146), whereas it was higher among schoolchildren (77.8%, n = 28/36); subjects of seven years of age had the highest odds of being colonized (odds ratio, OR = 5.176; p = 0.145). Pneumococcal serotypes included in the 13-valent conjugate vaccine formulation were largely detected in the study population and multiple serotypes colonization was considerable. Factors relating to a close proximity among people at the family level were statistically associated with pneumococcal carriage (OR = 2.121; p = 0.049), as well as active smoking habit with a clear dose-response effect (ORs = 1.017–3.326). About half of family clusters evidenced similar patterns of carried pneumococcal serotypes and the odds of sustaining a high level of intrafamilial sharing increased with household size (ORs = 1.083–5.000). This study highlighted the potential role played by the family environment in sustaining both the circulation and horizontal transmission of pneumococcus.

Prevalence of Candida albicans and carriage of Candida non-albicans in the saliva of preschool children, according to their caries status

OBJECTIVE

This study was conducted to establish associations among the Candida carriage rate, the diversity of Candida species carried and the different caries status of preschool children.

MATERIALS AND METHODS

Sixty-one children between 2 and 5 years of age were examined by a single expert examiner and were divided into three groups, the caries-free, moderate caries and severe caries groups, according to the criteria of the International Caries Detection and Assessment System II (ICDAS). Saliva samples were obtained from the members of each group and were plated on Sabouraud agar plates to assess the Candida carriage rates. CHROMagar Candida medium was used for the preliminary screening. Biochemical testing or PCR/sequencing was conducted to identify the different Candida species in the samples. The differences observed were considered significant if the p value was <0.05.

RESULTS

The Candida carriage rate and the number of species of this fungus carried were higher in the group with the highest level of caries severity (p < 0.05). Whereas Candida albicans was the most predominant Candida species in the saliva of all of the children, C. dubliniensis was identified only in the most caries-affected group in addition to other rare species of Candida non-albicans.

CONCLUSIONS

A high salivary Candida carriage rate and the presence of specific species of this fungus (such as C. albicans and C. dubliniensis) appear to be related to the severity of caries experienced by preschool children.

High group B streptococcus carriage rates in pregnant women in a tertiary institution in Nigeria

INTRODUCTION

In contrast to industrialized countries, until recently Group B Streptococcus (GBS) was infrequently reported in the developing world. This study was aimed at investigating the prevalence of GBS maternal colonization and to analyze the serotype distribution among the isolates.

METHODS

Vagino-rectal swabs collected from pregnant women were cultured for GBS using conventional media. Swabs were also taken from the mouths, ears and umbilical stumps of the neonates born to colonized mothers. Multiplex PCR and a conventional PCR to discern the gbs2018-ST-17 gene (specific for sequence type(ST)-17 clone) was performed to characterize the Group B streptococcus isolates.

RESULTS

A total of 300 pregnant women and 53 neonates were studied by culture but only 175 mothers by PCR. GBS was identified in four (6.8%) of 59 (19.7%) neonates of colonized mothers. Out of 175 mothers investigated by PCR, 112 (64%) were colonized. Serotype Ia (23.9%) was the most common among vagino-rectal isolates. Serotype II (71.4%) predominates among colonizing strain in newborns. A significant association between frequency of intercourse of > 2 per week and GBS carriage was found (t-test= 2.2; P value < 0.05).

CONCLUSION

GBS carriage is high with low transmission. Strains that have been associated with GBS neonatal disease were reported, though in very low rates. Though none of the babies studied had invasive GBS disease, a more expansive study in the future will be required to establish if invasive GBS neonatal disease is uncommon in Nigeria.

The multifaceted impact of pneumococcal conjugate vaccine implementation in children in France between 2001 to 2014

In 2003, France was the first European country to recommend 7-valent pneumococcal conjugate vaccine (PCV7) for a large proportion of healthy children. With complicated recommendations, the vaccine coverage during the first 4 y of implementation was low, then progressively increased to reach 90% in 2008. The aim of this review was to describe the particular impact of PCVs in a country where the vaccine coverage was initially suboptimal. After PCV7 implementation, the PCV7 serotypes nearly disappeared among pneumococci isolated from meningitis (-73%), other invasive pneumococcal disease (IPD; -90%) and pneumococcal carriage (-97%). Consequently, the rates of penicillin-resistant strains declined. However, because of important serotype replacement, the global effect on the incidence of meningitis (-31%) or other IPD (-14%) was modest and observed only in young children < 2 y old. After PCV13 transition, with immediate high vaccine coverage, the vaccine had an important impact on all pneumococcal disease: reduction of -20% for pneumococcal meningitis, -36% for non-meningitis IPD, -32% for community acquired pneumonia and -15% for S. pneumoniae carriage. These findings underline the complexity of pneumococcal epidemiology and the importance of high and fast vaccination coverage to obtain the optimal effect of PCVs.

Proton Pump Inhibitor Use Is Associated With Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae Rectal Carriage at Hospital Admission: A Cross-Sectional Study

In this cross-sectional study, 8.5% of patients using proton pump inhibitors (PPIs) were rectal carriers of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E), compared with 2.9% of non-PPI users. In multivariable analysis, PPI use was independently associated with ESBL-E rectal carriage at hospital admission (adjusted odds ratio, 3.89; 95% confidence interval, 1.65 - 9.19).

Limited Dissemination of Extended-Spectrum β-Lactamase- and Plasmid-Encoded AmpC-Producing Escherichia coli from Food and Farm Animals, Sweden

Food is a limited source of these antimicrobial resistance genes for humans.

Extended-spectrum β-lactamase (ESBL)– and plasmid-encoded ampC (pAmpC)–producing Enterobacteriaceae might spread from farm animals to humans through food. However, most studies have been limited in number of isolates tested and areas studied. We examined genetic relatedness of 716 isolates from 4,854 samples collected from humans, farm animals, and foods in Sweden to determine whether foods and farm animals might act as reservoirs and dissemination routes for ESBL/pAmpC-producing Escherichia coli. Results showed that clonal spread to humans appears unlikely. However, we found limited dissemination of genes encoding ESBL/pAmpC and plasmids carrying these genes from foods and farm animals to healthy humans and patients. Poultry and chicken meat might be a reservoir and dissemination route to humans. Although we found no evidence of clonal spread of ESBL/pAmpC-producing E. coli from farm animals or foods to humans, ESBL/pAmpC-producing E. coli with identical genes and plasmids were present in farm animals, foods, and humans.

High Nasal Carriage Rate of Staphylococcus aureus Containing Panton-Valentine leukocidin- and EDIN-Encoding Genes in Community and Hospital Settings in Burkina Faso

The objectives of the present study were to investigate the rate of S.aureus nasal carriage and molecular characteristics in hospital and community settings in Bobo Dioulasso, Burkina Faso. Nasal samples (n = 219) were collected from 116 healthy volunteers and 103 hospitalized patients in July and August 2014. Samples were first screened using CHROMagar Staph aureus chromogenic agar plates, and S. aureus strains were identified by mass spectrometry. Antibiotic susceptibility was tested using the disk diffusion method on Müller-Hinton agar. All S. aureus isolates were genotyped using DNA microarray. Overall, the rate of S. aureus nasal carriage was 32.9% (72/219) with 29% in healthy volunteers and 37% in hospital patients. Among the S. aureus isolates, only four methicillin-resistant S. aureus (MRSA) strains were identified and all in hospital patients (3.9%). The 72 S. aureus isolates from nasal samples belonged to 16 different clonal complexes, particularly to CC 152-MSSA (22 clones) and CC1-MSSA (nine clones). Two clones were significantly associated with community settings: CC1-MSSA and CC45-MSSA. The MRSA strains belonged to the ST88-MRSA-IV or the CC8-MRSA-V complex. A very high prevalence of toxinogenic strains 52.2% (36/69), containing Panton-Valentine leucocidin- and EDIN-encoding genes, was identified among the S. aureus isolates in community and hospital settings. This study provides the first characterization of S. aureus clones and their genetic characteristics in Burkina Faso. Altogether, it highlights the low prevalence of antimicrobial resistance, high diversity of methicillin-sensitive S. aureus clones and high frequency of toxinogenic S. aureus strains.

Copy Number Variation of Mitochondrial DNA Genes in Pneumocystis jirovecii According to the Fungal Load in BAL Specimens

Pneumocystis jirovecii is an unculturable fungus and the causative agent of Pneumocystis pneumonia, a life-threatening opportunistic infection. Although molecular diagnosis is often based on the detection of mtLSU rRNA mitochondrial gene, the number of copies of mitochondrial genes had not been investigated. We developed and optimized six real-time PCR assays in order to determine the copy number of four mitochondrial genes (mtSSU rRNA, mtLSU rRNA, NAD1, and CYTB) in comparison to nuclear genome (DHPS and HSP70) and tested 84 bronchoalveolar fluids of patients at different stages of the infection. Unexpectedly, we found that copy number of mitochondrial genes varied from gene to gene with mtSSU rRNA gene being more represented (37 copies) than NAD1 (23 copies), mtLSU rRNA (15 copies) and CYTB (6 copies) genes compared to nuclear genome. Hierarchical clustering analysis (HCA) allowed us to define five major clusters, significantly associated with fungal load (p = 0.029), in which copy number of mitochondrial genes was significantly different among them. More importantly, copy number of mtLSU rRNA, NAD1, and CYTB but not mtSSU rRNA differed according to P. jirovecii physiological state with a decreased number of copies when the fungal load is low. This suggests the existence of a mixture of various subspecies of mtDNA that can harbor different amplification rates. Overall, we revealed here an unexpected variability of P. jirovecii mtDNA copy number that fluctuates according to P. jirovecii’s physiological state, except for mtSSU that is the most stable and the most present mitochondrial gene.

Rate of colonization of health care workers by carbapenem-resistant Enterobacteriaceae in an endemic hospital: A prospective study

The role of health care workers in transmission of carbapenem-resistant Enterobacteriaceae (CRE) has not been evaluated thoroughly. We sought to determine the rate of fecal carriage of CRE among health care workers in our hospital, which is endemic for CRE (prevalence of 19 out of 800 beds and incidence of 128 out of 49,325 hospital admissions). We found no carriers among the 177 health care workers that participated in the study, suggesting that transmission does not occur through personnel gastrointestinal carriage of the bacteria.

Density, Serotype Diversity, and Fitness of Streptococcus pneumoniae in Upper Respiratory Tract Cocolonization With Nontypeable Haemophilus influenzae

BACKGROUND

 Coinfections by Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) are frequently implicated in complex otitis media. Whereas upper respiratory tract carriage precedes disease for both pathogens, interactions between species in cocolonized hosts are poorly understood. We compared colonization densities and the diversity and fitness of pneumococcal serotypes in single-species and mixed-species colonization.

METHODS

 We analyzed nasopharyngeal pneumococcal carriage and nasopharyngeal and oropharyngeal NTHi carriage in 13 541 samples collected over 6909 study visits from 769 children 2-30 months old in a 7-valent pneumococcal conjugate vaccine dosing trial. We measured density associations between the species and compared pneumococcal serotype diversity during and in the absence of NTHi colonization. We used logistic regression to quantify associations between NTHi colonization and previously published pneumococcal serotype factors related to fitness.

RESULTS

 Densities of the 2 species were positively associated when they co-occur in the nasopharynx. NTHi colonization was associated with reduced pneumococcal serotype diversity among children 2-18 months old and was more prevalent among children carrying pneumococcal serotypes with greater capsular thickness, neutrophil resistance, and metabolic efficiency.

CONCLUSIONS

 Pneumococcal-NTHi cocolonization is associated with an elevated density of both species and with reduced diversity and increased fitness of pneumococcal serotypes. NTHi colonization may create a selective environment favoring pneumococci with immune-evasive phenotypes.

Impact of the 13-Valent Pneumococcal Conjugate Vaccine on Pneumococcal Carriage Among American Indians

BACKGROUND

Community-wide impact of pneumococcal conjugate vaccines (PCV) is conferred by reductions in vaccine-type nasopharyngeal carriage. We evaluated the impact of PCV13 on carriage of PCV13-specific types (1, 3, 5, 6A, 7F and 19A) and 6C among American Indians.

METHODS

A nasopharyngeal specimen was collected from community members of all ages between January 2010 and April 2012 (3 months before and 24 months after PCV13 introduction). Pneumococci were isolated by culture and serotyped using antisera. Monthly carriage prevalence and PCV13 coverage were calculated to identify the timing of vaccine impact relative to PCV13 introduction. Prevalence ratios (PRs) were used to compare PCV13-specific carriage before and in years 1 and 2 of PCV13 use. Coverage was calculated according to age and number of doses received.

RESULTS

6645 participants (2859 <5 years and 3786 ≥5 years of age) provided 6628 specimens. A decline in PCV13-specific and type 6C carriage among children <5 years of age was observed 9 and 15 months after PCV13 introduction, respectively. Among underimmunized children, a decline in PCV13-specific carriage was observed 11 months after PCV13 introduction, when coverage in the community reached 58%. In year 2 of PCV13 use, PCV13-specific and 6C carriage were reduced by 60% and 70%, respectively (PCV13 specific: PR = 0.4, P < 0.001; 6C: PR = 0.3, P < 0.001) among children <5 years of age. The reduction in PCV13-specific carriage among those 5 to <8 years and 18+ years of age in year 2 of PCV13 use was not statistically significant.

CONCLUSIONS

PCV13 reduced PCV13-specific and 6C carriage among children <5 years of age. Low pre-PCV13 carriage prevalence of PCV13-specific types limited confirming this reduction for adults.

Relating Pneumococcal Carriage Among Children to Disease Rates Among Adults Before and After the Introduction of Conjugate Vaccines

The use of pneumococcal conjugate vaccines (PCVs) in children has a strong indirect effect on disease rates in adults. When children are vaccinated with PCVs, other serotypes that are not targeted by the vaccine can increase in frequency (serotype replacement) and reduce the direct and indirect benefits of the vaccine. To understand and predict the likely impacts of serotype replacement, it is important to know how patterns in the transmission of serotypes among children relate to disease rates in adults. We used data on pneumococcal carriage and disease from Navajo Nation children and adults collected before and after the routine use of PCVs (1998-2012). Using regression models within a Bayesian framework, we found that serotype-specific carriage and invasiveness (disease incidence divided by carriage prevalence) had similar patterns in children and adults. Moreover, carriage in children, invasiveness in children, and a serotype-specific random intercept (which captured additional variation associated with the serotypes) could predict the incidence serotype-specific pneumococcal disease in adults 18-39 years of age and those 40 years of age or older in the era of routine use of PCVs. These models could help us predict the effects of future pneumococcal vaccine use in children on disease rates in adults, and the modeling approach developed here could be used to test these findings in other settings.

Fecal Carriage of Staphylococcus aureus in the Hospital and Community Setting: A Systematic Review

BACKGROUND AND RATIONALE

Staphylococcus aureus fecal carriage has been identified as a potential source for nosocomial transmission and a risk factor for disease development. This systematic review determined the overall S. aureus [including methicillin susceptible and resistant S. aureus (MSSA and MRSA)] fecal carriage rates within the community and healthcare settings.

METHODOLOGY

Peer-reviewed articles indexed in Medline, Scopus, Academic Search Premier, Africa-Wide Information, CINAHL, and Web of Science were identified using applicable and controlled vocabulary through to 11 November 2015. Eligible studies were ascertained by three independent reviewers. Random-effects meta-analyses of proportions were performed to determine S. aureus, MSSA and MRSA fecal carriage rates reported by eligible studies.

RESULTS

Twenty six studies were included in this review. The pooled estimates for S. aureus, MSSA and MRSA fecal carriage were 26% (95% confidence interval (CI): 16.8-36.3%), 86% (95% confidence interval (CI): 65.9-97.9%) and 10% (95% CI: 0.7-27.0%), respectively. Fecal S. aureus carriage rates increased on average from 10 to 65% during the first 8 weeks of life, followed by an average carriage rate of 64% at 6 months and 46% at 1 year of life. Genotyping techniques were employed mainly in studies conducted in developed countries and comprised largely of gel-based techniques. Six studies reported on the role of S. aureus fecal strains in diarrhea (n = 2) and the risk for acquiring infections (n = 4). Eight of the 26 studies included in this review performed antibiotic susceptibility testing of S. aureus fecal isolates.

CONCLUSION

This study provides evidence that screening for S. aureus fecal carriage, at least in populations at high risk, could be an effective measure for the prevention of S. aureus transmission and infection in the healthcare and community setting. More well-structured studies need to be conducted and sequence-based genotyping techniques should be employed for the comparison of isolates on a global scale in both developing and developed countries.

Infection with and Carriage of Mycoplasma pneumoniae in Children

“Atypical” pneumonia was described as a distinct and mild form of community-acquired pneumonia (CAP) already before Mycoplasma pneumoniae had been discovered and recognized as its cause. M. pneumoniae is detected in CAP patients most frequently among school-aged children from 5 to 15 years of age, with a decline after adolescence and tapering off in adulthood. Detection rates by polymerase chain reaction (PCR) or serology in children with CAP admitted to the hospital amount 4–39%. Although the infection is generally mild and self-limiting, patients of every age can develop severe or extrapulmonary disease. Recent studies indicate that high rates of healthy children carry M. pneumoniae in the upper respiratory tract and that current diagnostic PCR or serology cannot discriminate between M. pneumoniae infection and carriage. Further, symptoms and radiologic features are not specific for M. pneumoniae infection. Thus, patients may be unnecessarily treated with antimicrobials against M. pneumoniae. Macrolides are the first-line antibiotics for this entity in children younger than 8 years of age. Overall macrolides are extensively used worldwide, and this has led to the emergence of macrolide-resistant M. pneumoniae, which may be associated with severe clinical features and more extrapulmonary complications. This review focuses on the characteristics of M. pneumoniae infections in children, and exemplifies that simple clinical decision rules may help identifying children at high risk for CAP due to M. pneumoniae. This may aid physicians in prescribing appropriate first-line antibiotics, since current diagnostic tests for M. pneumoniae infection are not reliably predictive.

Routinely vaccinating adolescents against meningococcus: targeting transmission & disease

Adolescents have the highest rates of meningococcal carriage and transmission. Interrupting the adolescent habitat in order to reduce carriage and transmission within adolescents and to other age groups could help to control meningococcal disease at a population level. Compared to immunization strategies restricted to young children, a strategy focused on adolescents may have more profound and long-lasting indirect impacts, and may be more cost effective. Despite challenges in reaching this age-group, experience with other vaccines show that high vaccine coverage of adolescents is attainable.

Current Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in Elderly French People: Troublesome Clones on the Horizon

Objective: In 2015, we conducted at 44 healthcare facilities (HCFs) and 21 nursing homes (NHs) a 3-month bloodstream infection (BSI) survey, and a 1-day prevalence study to determine the rate of carriage of methicillin-resistant Staphylococcus aureus (MRSA) in 891 patients and 470 residents. We investigated the molecular characteristics of the BSI-associated and colonizing MRSA isolates, and assessed cross-transmission using double-locus sequence typing and pulsed-field gel electrophoresis protocol.

Results: The incidence of MRSA-BSI was 0.040/1000 patient-days (19 cases). The prevalence of MRSA carriage was 4.2% in patients (n = 39) and 8.7% in residents (n = 41) (p < 0.001). BSI-associated and colonizing isolates were similar: none were PVL-positive; 86.9% belonged to clonal complexes 5 and 8; 93.9% were resistant to fluoroquinolones. The qacA/B gene was carried by 15.8% of the BSI-associated isolates [3/3 BSI cases in intensive care units (ICUs)], and 7.7% of the colonizing isolates in HCFs. Probable resident-to-resident transmission was identified in four NHs.

Conclusion: Despite generally reassuring results, we identified two key concerns. First, a worryingly high prevalence of the qacA/B gene in MRSA isolates. Antisepsis measures being crucial to prevent healthcare-associated infections, our findings raise questions about the potential risk associated with chlorhexidine use in qacA/B⁺ MRSA carriers, particularly in ICUs. Second, NHs are a weak link in MRSA control. MRSA spread was not controlled at several NHs; because of their frequent contact with the community, conditions are favorable for these NHs to serve as reservoirs of USA300 clone for local HCFs.

Genomic Analysis of Serogroup Y Neisseria meningitidis Isolates Reveals Extensive Similarities Between Carriage-Associated and Disease-Associated Organisms

BACKGROUND

Neisseria meningitidis is a frequent colonizer of the human nasopharynx, with asymptomatic carriage providing the reservoir for invasive, disease-causing strains. Serogroup Y (MenY) strains are a major cause of meningococcal disease. High-resolution genetic analyses of carriage and disease isolates can establish epidemiological relationships and identify potential virulence factors.

METHODS

Whole-genome sequence data were obtained for 99 MenY carriage isolates recovered in the United Kingdom during 1997-2010. Sequences were compared to those of 73 MenY invasive isolates recovered during 2010-2011, using a gene-by-gene approach.

RESULTS

Comparisons across 1605 core genes resolved 91% of isolates into one of 8 clusters containing closely related disease and carriage isolates. Six clusters contained carried meningococci isolated during 1997-2001, suggesting temporal stability. One cluster of isolates, predominately sharing the designation Y: P1.5-1,10-1: F4-1: ST-1655 (cc23), was resolved into one subcluster with 86% carriage isolates and a second with 90% invasive isolates. These subclusters were defined by specific allelic differences in 5 core genes encoding glycerate kinase (glxK), valine-pyruvate transaminase (avtA), superoxide dismutase (sodB), and 2 hypothetical proteins.

CONCLUSIONS

High-resolution genetic analyses detected long-term temporal stability and temporally overlapping carriage and disease populations for MenY clones but also evidence of a disease-associated clone.

Pneumococcal Acquisition Among Infants Exposed to HIV in Rural Malawi: A Longitudinal Household Study

The prevalence of Streptococcus pneumoniae (pneumococcus) carriage is higher in adults who are infected with human immunodeficiency virus (HIV) than in adults who are not. We hypothesized that infants exposed to HIV become carriers of nasopharyngeal pneumococcus earlier and more frequently than infants who are not exposed to HIV. We compared infant pneumococcal acquisition by maternal HIV status and household exposure in Karonga District, Malawi, in 2009–2011, before the introduction of pneumococcal conjugate vaccine. Nasopharyngeal swabs were collected every 4–6 weeks in the first year of life from infants with known HIV-exposure status, their mothers, and other household members. We studied infant pneumococcal acquisition by maternal HIV status, serotype-specific household exposure, and other risk factors, including seasonality. We recruited 54 infants who were exposed to HIV and 131 infants who were not. There was no significant difference in pneumococcal acquisition by maternal HIV status (adjusted rate ratio (aRR) = 1.00, 95% confidence interval (CI): 0.87, 1.15). Carriage by the mother was associated with greater acquisition of the same serotype (aRR = 3.09, 95% CI: 1.47, 6.50), but the adjusted population attributable fraction was negligible (1.9%, 95% CI: 0.0, 4.3). Serotype-specific exposure to children under 5 years of age was associated with higher acquisition (aRR = 4.30, 95% CI: 2.80, 6.60; adjusted population attributable fraction = 8.8%, 95% CI: 4.0, 13.4). We found no evidence to suggest that maternal HIV infection would affect the impact of pneumococcal vaccination on colonization in this population.

Effects of carrying handles, postures, materials and distances on carrying capability

This study recruited 14 industrial workers to examine the effects of carrying handles, postures, materials and distances on maximum acceptable weights of carrying (MAWC), and resulting heart rate and body rating of perceived exertion (RPE) for a 20 min intensive carrying task. This study showed that MAWC of carrying with bar handles, carrying with hands-and-body posture, solid materials and 4 m distance were significantly higher than that of carrying with groove handles, carrying with hands posture, liquid materials and 8 m distance, respectively. The resulting heart rates while carrying MAWCs of groove handles, hands-and-body carrying posture, solid materials and 4 m distance were lower than the resulting heart rates while carrying MAWCs of bar handles, hands carrying posture, liquid materials and 8 m distance, respectively. Most pair levels of independent variables resulted in similar body's RPEs except for the pair levels of carrying distance.

Prevalence and risk factors for methicillin resistant Staphylococcus aureus carriage among emergency department workers and bacterial contamination on touch surfaces in Erciyes University Hospital, Kayseri, Turkey

OBJECTIVE

The aim of this study was to determine Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) nasal carriage among emergency department (ED) workers, and bacterial contamination on hand-touch surfaces at ED.

METHODS

This single-centered study enrolled 105 ED workers and 190 hand-touch surfaces at ED in June 2014. Nasal and environmental samples for S. aureus carriage and for bacterial contamination were obtained. For isolation swabs were cultured on ChromAgar S. aureus and environmental samples first cultured in broth and antibiogram obtained by clinical and Laboratory Standards Institute guidelines. A questionnaire was completed for each subject.

RESULTS

The S. aureus carriage rate was 18.1% (n=19), with 2.9% (n=3) MRSA positivity. There were two (1.9%) mobile phone positivities for S. aureus, one of them was MRSA, and a computer keyboard contamination for MRSA was also detected. All MRSA isolates were susceptible for the tested antibiotics. There was significant difference between gender (p=0.044) in terms of nasal carriage of S. aureus and MRSA, all three MRSA isolates were from females.

CONCLUSION

Our study showed that the carriage of MRSA was not affected by clinical exposure in the hospital because of the existing infection control policy in our hospital.

Persisting high prevalence of pneumococcal carriage among HIV-infected adults receiving antiretroviral therapy in Malawi: a cohort study

OBJECTIVE

HIV-infected adults have high rates of pneumococcal carriage and invasive disease. We investigated the effect of antiretroviral therapy (ART) on pneumococcal carriage in HIV-infected adults prior to infant pneumococcal conjugate vaccine (PCV) rollout.

DESIGN

Observational cohort study.

METHODS

We recruited HIV-infected adults newly attending a rural HIV clinic in northern Malawi between 2008 and 2010. Nasopharyngeal samples were taken at baseline and after 6, 12, 18 and 24 months. We compared pneumococcal carriage by ART status using generalized estimated equation models adjusted for CD4 cell count, sex, seasonality, and other potential confounders.

RESULTS

In total, 336 individuals were included, of which 223 individuals started ART during follow-up. Individuals receiving ART had higher pneumococcal carriage than individuals not receiving ART (25.9 vs. 19.8%, P = 0.03) particularly for serotypes not included in PCV13 (16.1 vs. 9.6% P = 0.003). Following adjustment, increased carriage of non-PCV13 serotypes was still observed for individuals on ART, but results for all serotypes were nonsignificant [all serotypes: adjusted risk ratio (aRR) 1.22 (0.95-1.56); non-PCV13 serotypes: aRR 1.72, 95% CI 1.13-2.62].

CONCLUSION

Pneumococcal carriage in HIV-infected adults in Malawi remained high despite use of ART, consistent with failure of mucosal immune reconstitution in the upper respiratory tract. There was evidence of increased carriage of non-PCV13 serotypes. HIV-infected adults on ART could remain an important reservoir for pneumococcal diversity post infant pneumococcal vaccine introduction. Control of pneumococcal disease in African HIV remains a priority.