Lack of Interference between Streptococcus pneumoniae and Staphylococcus aureus in HIV-infected individuals?
Explore the source record for details and available documents.
Antibiosis↗
Biomedical subjects
Alex van Belkum
Publications and source records attributed to Alex van Belkum.
Staphylococcus aureus nasal carriage is associated with glucocorticoid receptor gene polymorphisms.
The aim of this study was to determine whether polymorphisms of the glucocorticoid receptor gene, influencing glucocorticoid sensitivity, are associated with persistent nasal carriage of Staphylococcus aureus. Two nasal swab cultures were obtained from each of 2,929 participants. Subjects were classified as persistent carriers (n=563) if both cultures were positive. GG homozygotes of the exon 9beta polymorphism were associated with a 68% reduced risk of persistent S. aureus nasal carriage, whereas carriers of the codon 23 lysine allele displayed an 80% increased risk. Thus, genotype-dependent variation in the sensitivity to glucocorticoids is associated with tolerance toward staphylococcal nasal colonization.
Aged↗
Translationally controlled tumor protein from Madurella mycetomatis, a marker for tumorous mycetoma progression.
About 40 years ago Abs against the fungus Madurella mycetomatis were first demonstrated to be present in eumycetoma patients, a disease characterized by tumorous swellings. To date nothing is known about the individual immunoreactive Ags present in this fungus. In the present study, we identify its first immunogenic Ag, a protein homologous to the translationally controlled tumor protein (TCTP), a well-conserved histamine release factor in a range of eukaryotes. The gene for this Ag was demonstrated to be present in two variants in M. mycetomatis, with 13% aa difference between the two proteins encoded. In vitro, TCTP was secreted into the culture medium. In vivo, it was found to be expressed on hyphae present in developing stages of the eumycetoma-characteristic black grain. Significant IgG and IgM immune responses, against the whole protein and selected M. mycetomatis-specific peptides, were determined. The Ab levels correlated with lesion size and disease duration. Overall, the patients with the largest lesions had the highest Ab level, which lowered with decreasing size of the lesion. After 6-15 years of disease duration the Ab levels were the highest. TCTP is the first well-characterized immunogenic Ag, simultaneously the first monomolecular vaccine candidate, identified for the fungus M. mycetomatis.
Adult↗
Identification of DNA sequence variation in Campylobacter jejuni strains associated with the Guillain-Barré syndrome by high-throughput AFLP analysis.
BACKGROUND: Campylobacter jejuni is the predominant cause of antecedent infection in post-infectious neuropathies such as the Guillain-Barré (GBS) and Miller Fisher syndromes (MFS). GBS and MFS are probably induced by molecular mimicry between human gangliosides and bacterial lipo-oligosaccharides (LOS). This study describes a new C. jejuni-specific high-throughput AFLP (htAFLP) approach for detection and identification of DNA polymorphism, in general, and of putative GBS/MFS-markers, in particular. RESULTS: We compared 6 different isolates of the "genome strain" NCTC 11168 obtained from different laboratories. HtAFLP analysis generated approximately 3000 markers per stain, 19 of which were polymorphic. The DNA polymorphisms could not be confirmed by PCR-RFLP analysis, suggesting a baseline level of 0.6% AFLP artefacts. Comparison of NCTC 11168 with 4 GBS-associated strains revealed 23 potentially GBS-specific markers, 17 of which were identified by DNA sequencing. A collection of 27 GBS/MFS-associated and 17 enteritis control strains was analyzed with PCR-RFLP tests based on 11 of these markers. We identified 3 markers, located in the LOS biosynthesis genes cj1136, cj1138 and cj1139c, that were significantly associated with GBS (P = 0.024, P = 0.047 and P < 0.001, respectively). HtAFLP analysis of 13 highly clonal South African GBS/MFS-associated and enteritis control strains did not reveal GBS-specific markers. CONCLUSION: This study shows that bacterial GBS markers are limited in number and located in the LOS biosynthesis genes, which corroborates the current consensus that LOS mimicry may be the prime etiologic determinant of GBS. Furthermore, our results demonstrate that htAFLP, with its high reproducibility and resolution, is an effective technique for the detection and subsequent identification of putative bacterial disease markers.
Bacterial Proteins↗
Identification of a sialate O-acetyltransferase from Campylobacter jejuni: demonstration of direct transfer to the C-9 position of terminalalpha-2, 8-linked sialic acid.
We have identified a sialate O-acetyltransferase in the lipo-oligosaccharide biosynthesis locus of Campylobacter jejuni. Strains possessing this locus are known to produce sialylated outer core structures that mimic host gangliosides, and have been implicated in triggering the onset of Guillain-Barré syndrome. The acetyltransferase, which was cloned and expressed as a fusion construct in Escherichia coli, is soluble and homologous with members of the NodL-LacA-CysE family of O-acetyltransferases. This enzyme catalyzes the transfer of O-acetyl groups onto oligosaccharide-bound sialic acid, with a high specificity for terminal alpha2,8-linked residues. The modification is directed to C-9 and not C-7 as is believed to occur more commonly in other organisms. Despite their wide prevalence and importance in both eukaryotes and prokaryotes, this is the first report to describe the characterization of a purified sialate O-acetyltransferase.
Acetyltransferases↗
Staphylococcal colonization and infection: homeostasis versus disbalance of human (innate) immunity and bacterial virulence.
PURPOSE OF REVIEW: This review identifies trends in the study of interactions between Staphylococcus aureus and humans. When nasal colonization is in the neutral state, infection clearly represents a state of host-pathogen disbalance. The features leading from apparent homeostatic colonization to pathogenesis are identified at an increasing rate. RECENT FINDINGS: Persistent carriage of S. aureus predisposes to infection but limits bacteraemia-associated mortality. Intermittent carriage is usually imposed and of lesser clinical relevance. The nature and function of several staphylococcal virulence factors have been elucidated and near complete gene catalogues have been established. There does not seem to be a difference in virulence, however, between methicillin-susceptible and resistant S. aureus. Biological selection takes place in the nose and innate immune features relevant to colonization have been discovered. Acquired immunity remains underexposed, but the host factors involved in the host-pathogen interaction have been identified. SUMMARY: Virulence assessment of S. aureus has been facilitated by novel technology: genome-wide inventories of virulence potential can be made and new pathogenic mechanisms have been presumptively identified. These involve invasion procedures but also (innate) immune evasion strategies. These cross-fertilizing developments shed light on the feasibility of novel prophylactic or therapeutic strategies for combating staphylococcal carriage and disease.
Antibodies, Bacterial↗
Unveiling electrotransformation of Moraxella catarrhalis as a process of natural transformation.
The human respiratory tract pathogen Moraxella catarrhalis is a naturally competent microorganism. However, electrotransformation has long been used to introduce foreign DNA into this organism. This study demonstrated that electrotransformants obtained with linear or circular nonreplicating plasmid DNA originated exclusively from natural transformation processes taking place during the recovery phase after the application of current. Only replicating plasmid DNA could be introduced into M. catarrhalis by electrotransformation, in a type IV pilus-independent manner. Electrotransformation with homologous genomic DNA indicated that restriction of double-stranded DNA was independent of type III restriction-methylation systems. Nontransformability of M. catarrhalis by electrotransformation was observed using double- as well as single-stranded DNA. In addition, the study showed that natural competence is a very constant feature of M. catarrhalis.
DNA↗
Staphylococcus aureus carriage patterns and the risk of infections associated with continuous peritoneal dialysis.
The epidemiology and risks of Staphylococcus aureus carriage in continuous peritoneal dialysis (CPD) patients was studied in a single tertiary-care institution. On outpatient visits samples for culture were routinely taken prospectively from the CPD catheter exit site and the vestibulum nasi. Seventy-five patients with at least one culture positive for S. aureus in this period were included: 43 had genotypically identical S. aureus strains in over 80% of the cultures and were classified as persistent carriers; 32 were intermittent carriers. Persistent carriage was associated with a threefold higher risk for CPD-related infections and sixfold higher rates of vancomycin consumption compared to those for the intermittent carriers. No methicillin or vancomycin resistance was detected.
Adolescent↗
Candida krusei transmission among hematology patients resolved by adapted antifungal prophylaxis and infection control measures.
A sudden increase in neutropenic hematology patients with Candida krusei colonization and bacteremia prompted a longitudinal epidemiological investigation. We identified 39 patients; 13 developed candidemia, and three died; 25 patients carried the same genotype. We intervened by changing antifungal prophylaxis and implementing strict infection control measures. The incidence dropped immediately.
Antifungal Agents↗
Distribution of the serine-aspartate repeat protein-encoding sdr genes among nasal-carriage and invasive Staphylococcus aureus strains.
The sdr locus was found in all 497 investigated Staphylococcus aureus strains, although in 29 strains it contained only the sdrC gene (sdrD negative, sdrE negative). The sdrC-positive, sdrD-negative, sdrE-negative gene profile was exclusive to methicillin-sensitive S. aureus (MSSA) strains (Fisher's exact test; P = 0.0005) and was not found in the strains collected from bone infections (P = 0.0019). We also found a strong association between the presence of the sdrD gene and methicillin-resistant S. aureus strains (P < 0.0001). Our findings suggest that MSSA strains with the newly uncovered sdrC-positive, sdrD-negative, sdrE-negative gene profile have a substantially decreased potential to establish bone infection.
Bacterial Proteins↗
Clonal distribution and differential occurrence of the enterotoxin gene cluster, egc, in carriage- versus bacteremia-associated isolates of Staphylococcus aureus.
The Staphylococcus aureus enterotoxin gene cluster, egc, was detected in isolates from healthy individuals and in those from patients with bacteremia. The egc genes cooccur and are slightly enriched in strains from healthy carriers (present in 63.7% of carriage-associated isolates versus 52.9% of invasive isolates; P = 0.03). Multilocus sequence typing revealed that successful staphylococcal clones usually harbor the egc locus.
Bacteremia↗
Realtime PCR on urine sediments in the diagnosis of trichomoniasis in male subjects.
Explore the source record for details and available documents.
Animals↗
Panton-Valentine leukocidin genes in Staphylococcus aureus.
Explore the source record for details and available documents.
Adolescent↗
Direct detection of human Staphylococcus aureus carriage in the nose using the Lightcycler Staphylococcus kit.
The Lightcycler Staphylococcus kit is a diagnostic tool for direct real-time detection of Staphylococcus aureus in clinical materials. We show here that detection of S. aureus nasal carriage using this test is hampered by competition of DNA from coagulase-negative staphylococci. However the test is well suited for species identification after culture and the identification of high-load S. aureus carriers.
Carrier State↗
Associations between Staphylococcus aureus Genotype, Infection, and In-Hospital Mortality: A Nested Case-Control Study.
We screened 14,008 adult nonsurgical patients for Staphylococcus aureus nasal carriage at hospital admission and assessed them for invasive S. aureus disease and in-hospital mortality. Multilocus sequence typing was performed on endogenous invasive strains and nasal strains of matched asymptomatic carriers to investigate whether virulent clones could be identified in nasal carriers. Clonal complex (CC) 45 was significantly underrepresented (odds ratio [OR], 0.16 [95% confidence interval {CI}, 0.04-0.59]) and CC30 was overrepresented (not statistically significant) among invasive strains (OR, 1.91 [95% CI, 0.91-4.0]). The distribution of CCs of invasive S. aureus strains in noncarriers did not differ from that in carriers. Those infected with S. aureus strains belonging to a CC had higher mortality than those infected with strains not belonging to a CC (P<.05), which indicates the coevolution of S. aureus virulence and spread in humans.
Adult↗
Moraxella catarrhalis is only a weak activator of the mannose-binding lectin (MBL) pathway of complement activation.
A hemolytic bystander assay was used to assess the functional serum mannose-binding lectin (MBL) activating capacity of five isolates of Moraxella catarrhalis obtained from children who suffered recurrent acute otitis media episodes. Results showed that this organism is only a poor activator of the lectin pathway of complement activation, with subsequent consequences for the etiology of otitis media by this organism.
Child↗
Staphylococcus aureus nasal carriage is not associated with known polymorphism in the Vitamin D receptor gene.
The vitamin D endocrine system has been shown to influence the immune response and polymorphisms in the vitamin D receptor (VDR) gene have been associated with susceptibility to infectious diseases. We determined if the Cdx2, FokI and BsmI-ApaI-TaqI polymorphisms in the VDR gene were associated with nasal carriage of Staphylococcal aureus. We defined the S. aureus nasal carriage status (persistent, intermittent or non-carriage) for a group of more that 2000 elderly volunteers. The prevalence of persistent S. aureus nasal carriage was 18%, which was, however, not associated with any of the variant VDR genotypes. Our study into genetic determinants of S. aureus carriage patterns is the largest in the field, but still we found no association between VDR gene variation and S. aureus nasal carriage.
Aged↗
International spread of major clones of methicillin resistant Staphylococcus aureus: nosocomial endemicity of multi locus sequence type 239 in Saudi Arabia and Romania.
Phenotypically identified methicillin resistant Staphylococcus aureus (MRSA) strains from several hospitals in Romania and Saudi Arabia (n = 103 and 68, respectively) were confirmed to be MRSA by mecA PCR and PBP-2' based latex agglutination. Subsequently, strains were differentiated at the sub-species level using pulsed field gel electrophoresis (PFGE) of SmaI DNA macro-restriction fragments. Comparison of the PFGE fingerprints identified major clusters of strains, persistently present in the various hospitals. Endemicity of certain strains was identified, amongst others one due to a particularly methicillin resistant type in the burn wound sector of the Romanian hospital. No PFGE-based overlap was found between the Saudi and Romanian strains. However, multi locus sequence typing (MLST), performed for 20% of all strains, revealed that genuine genetic similarity was obscured by the PFGE analysis. In both the Romanian and Saudi hospitals the renowned sequence type (ST) 239 was very over-represented. This was especially apparent in Saudi Arabia, where all strains except two shared the ST 239 genotype. This clonal type has previously been identified in a variety of other countries. Despite the MLST concordance, PFGE data indicate that ST 239 diversifies while maintaining its core genome intact. ST 80, another previously but less frequently identified clone, was introduced in 2000 in the Romanian institutes and persisted over the past 3 years as a frequent cause of infections in a surgical department. The successful MRSA types can acquire prominent positions in hospitals of previously low-endemicity MRSA status.
Bacterial Typing Techniques↗