Colony variation in Staphylococcus lugdunensis

Staphylococcus lugdunensis Endocarditis Causing Secondary Splenic Abscess: A Potentially Lethal Complication

Infective endocarditis is a potentially life-threatening condition caused by a bacterial infection of the heart valves. The incidence of splenic abscess associated with infective endocarditis varies between 1-10% of cases, and its presence may indicate a severe form of the disease. We present a 24-year-old man diagnosed with infective endocarditis who was found to have a splenic abscess upon further evaluation. The patient was initially managed conservatively with targeted antibiotics, but after unsuccessful percutaneous drainage, a splenectomy was performed. The patient underwent mitral valve replacement surgery and made a good recovery. The patient's case highlights the importance of considering a secondary abscess in the management of infective endocarditis. This complication can easily be missed and cause significant morbidity. This case underscores the importance of early diagnosis and effective collaboration between various healthcare professionals to achieve the best possible outcome for patients with infective endocarditis and its associated complications.

Longitudinal characterization of multispecies microbial populations recovered from spaceflight potable water

While sequencing technologies have revolutionized our knowledge of microbial diversity, little is known about the dynamic emergent phenotypes that arise within the context of mixed-species populations, which are not fully predicted using sequencing technologies alone. The International Space Station (ISS) is an isolated, closed human habitat that can be harnessed for cross-sectional and longitudinal functional microbiome studies. Using NASA-archived microbial isolates collected from the ISS potable water system over several years, we profiled five phenotypes: antibiotic resistance, metabolism, hemolysis, and biofilm structure/composition of individual or multispecies communities, which represent characteristics that could negatively impact astronaut health and life-support systems. Data revealed a temporal dependence on interactive behaviors, suggesting possible microbial adaptation over time within the ecosystem. This study represents one of the most extensive phenotypic characterization of ISS potable water microbiota with implications for microbial risk assessments of water systems in built environments in space and on Earth.

Emergency Endovascular Management of a Symptomatic Pseudoaneurysm of the Left Subclavian Artery Ostium Using a Combination of an Abdominal Aortic Stent-Graft Extension Cuff and a Periscope Stent Graft

A pseudoaneurysm located at the subclavian artery ostium is an infrequent but life-threatening pathology that usually requires major thoracic surgery with a high risk of mortality and morbidity. Endovascular therapy applied to the aortic arch branches is a recent alternative technique, which is still in its early stages because dedicated endovascular devices for the aortic arch are lacking. In this article, we present the emergency endovascular management of a symptomatic pseudoaneurysm of the left subclavian artery ostium which was presumably secondary to an atherosclerotic plaque rupture. Endovascular exclusion required a combination of an abdominal aortic stent-graft extension cuff, which was placed via a retroperitoneal iliac access, and a subclavian artery periscope stent graft.

Phenotypic variants of staphylococci and their underlying population distributions following exposure to stress

This study investigated whether alterations in environmental conditions would induce the formation of small colony variant phenotypes (SCV) with associated changes in cell morphology and ultra-structure in S. aureus, s. epidermidis, and S. lugdunensis. Wild-type clinical isolates were exposed to low temperature (4 °C), antibiotic stress (penicillin G and vancomycin; 0-10,000 µg mL(-1)), pH stress (pH 3-9) and osmotic challenge (NaCl concentrations of 0-20%). Changes in cell diameter, cell-wall thickness, and population distribution changes (n ≥ 300) were assessed via scanning and transmission electron microscopy (SEM and TEM), and compared to control populations. Our analyses found that prolonged exposure to all treatments resulted in the subsequent formation of SCV phenotypes. Observed SCVs manifested as minute colonies with reduced haemolysis and pigmentation (NaCl, pH and 4°C treatments), or complete lack thereof (antibiotic treatments). SEM comparison analyses revealed significantly smaller cell sizes for SCV populations except in S. aureus and S. epidermidis 10% NaCl, and S. epidermidis 4 °C (p<0.05). Shifts in population distribution patterns were also observed with distinct sub-populations of smaller cells appearing for S. epidermidis, and S. lugdunensis. TEM analyses revealed significantly thicker cell-walls in all treatments and species except S. lugdunensis exposed to 4 °C. These findings suggest that staphylococci adapted to environmental stresses by altering their cell size and wall thickness which could represent the formation of altered phenotypes which facilitate survival under harsh conditions. The phenotypic response was governed by the type of prevailing environmental stress regime leading to appropriate alterations in ultra-structure and size, suggesting downstream changes in gene expression, the proteome, and metabolome.

Staphylococcus lugdunensis: the coagulase-negative staphylococcus you don't want to ignore

Staphylococcus lugdunensis is a virulent coagulase-negative staphylococcus (CoNS) that behaves like Staphylococcus aureus. Toxic shock syndrome, osteomyelitis, septic arthritis and postoperative endopthalmitis have been observed. Endocarditis complicated by heart failure, periannular abscess formation and embolic phenomenon have brought particular attention to this CoNS. Mortality rates for endocarditis appear higher when compared with other CoNS. Owing to the laboratory methods used, identification may be misleading. β-lactam antimicrobials are recommended pending sensitivities. Evaluation for endocarditis should be pursued in bacteremic patients due to its pathogenic potential.

Effect of low temperature on growth and ultra-structure of Staphylococcus spp

The effect of temperature fluctuation is an important factor in bacterial growth especially for pathogens such as the staphylococci that have to remain viable during potentially harsh and prolonged transfer conditions between hosts. The aim of this study was to investigate the response of S. aureus, S. epidermidis, and S. lugdunensis when exposed to low temperature (4°C) for prolonged periods, and how this factor affected their subsequent growth, colony morphology, cellular ultra-structure, and amino acid composition in the non-cytoplasmic hydrolysate fraction. Clinical isolates were grown under optimal conditions and then subjected to 4°C conditions for a period of 8 wks. Cold-stressed and reference control samples were assessed under transmission electron microscopy (TEM) to identify potential ultra-structural changes. To determine changes in amino acid composition, cells were fractured to remove the lipid and cytoplasmic components and the remaining structural components were hydrolysed. Amino acid profiles for the hydrolysis fraction were then analysed for changes by using principal component analysis (PCA). Exposure of the three staphylococci to prolonged low temperature stress resulted in the formation of increasing proportions of small colony variant (SCV) phenotypes. TEM revealed that SCV cells had significantly thicker and more diffuse cell-walls than their corresponding WT samples for both S. aureus and S. epidermidis, but the changes were not significant for S. lugdunensis. Substantial species-specific alterations in the amino acid composition of the structural hydrolysate fraction were also observed in the cold-treated cells. The data indicated that the staphylococci responded over prolonged periods of cold-stress treatment by transforming into SCV populations. The observed ultra-structural and amino acid changes were proposed to represent response mechanisms for staphylococcal survival amidst hostile conditions, thus maintaining the viability of the species until favourable conditions arise again.

Staphylococcus lugdunensis, a common cause of skin and soft tissue infections in the community

Staphylococcus lugdunensis, a rare cause of severe infections such as native valve endocarditis, often causes superficial skin infections similar to Staphylococcus aureus infections. We initiated a study to optimize the identification methods in the routine laboratory, followed by a population-based epidemiologic analysis of patients infected with S. lugdunensis in Viborg County, Denmark. Recognition of a characteristic Eikenella corrodens-like odor on Columbia sheep blood agar combined with colony pleomorphism and prominent beta-hemolysis after 2 days of incubation, confirmed by API-ID-32 Staph, led to an 11-fold increase in the detection of S. lugdunensis. By these methods we found 491 S. lugdunensis infections in 4 years, corresponding to an incidence of 53 per 100,000 per year, an increase from 5 infections per 100,000 inhabitants in the preceding years. Seventy-five percent of the cases were found in general practice; these were dominated by skin abscesses (36%), wound infections (25%), and paronychias (13%). Fifty-six percent of the infections occurred below the waist, and toes were the most frequently infected site (21%). Only 3% of the patients suffered from severe invasive infections. The median age was 52 years, and the male/female ratio was 0.69. Our study shows that S. lugdunensis is a common cause of skin and soft-tissue infections (SSTI) and is probably underrated by many laboratories. S. lugdunensis should be accepted as a significant pathogen in SSTI and should be looked for in all routine bacteriological examinations, and clinicians should be acquainted with the name and the pathology of the bacterium.

From clinical microbiology to infection pathogenesis: how daring to be different works for Staphylococcus lugdunensis

Staphylococcus lugdunensis has gained recognition as an atypically virulent pathogen with a unique microbiological and clinical profile. S. lugdunensis is coagulase negative due to the lack of production of secreted coagulase, but a membrane-bound form of the enzyme present in some isolates can result in misidentification of the organism as Staphylococcus aureus in the clinical microbiology laboratory. S. lugdunensis is a skin commensal and an infrequent pathogen compared to S. aureus and S. epidermidis, but clinically, infections caused by this organism resemble those caused by S. aureus rather than those caused by other coagulase-negative staphylococci. S. lugdunensis can cause acute and highly destructive cases of native valve endocarditis that often require surgical treatment in addition to antimicrobial therapy. Other types of S. lugdunensis infections include abscess and wound infection, urinary tract infection, and infection of intravascular catheters and other implanted medical devices. S. lugdunensis is generally susceptible to antimicrobial agents and shares CLSI antimicrobial susceptibility breakpoints with S. aureus. Virulence factors contributing to this organism's heightened pathogenicity remain largely unknown. Those characterized to date suggest that the organism has the ability to bind to and interact with host cells and to form biofilms on host tissues or prosthetic surfaces.

Staphylococcus lugdunensis pacemaker-related infection

We report the first known case of a device-related bloodstream infection involving Staphylococcus lugdunensis small-colony variants. Recurrent pacemaker-related bloodstream infection within a period of 10 months illustrates the poor clinical and microbiologic response even to prolonged antimicrobial drug therapy in a patient infected with this staphylococcal subpopulation.

Genotypic versus phenotypic characterization, with respect to susceptibility and identification, of 17 clinical isolates of Staphylococcus lugdunensis

OBJECTIVES

To compare different methods for the identification and determination of susceptibility to penicillin and methicillin of Staphylococcus lugdunensis.

METHODS

Seventeen clinical isolates of S. lugdunensis (identified by PCR amplification and sequencing of the rpoB gene) were studied using the ATB32-Staph, Crystal, Vitek 2 and Wider commercial systems. The clumping factor test and the tube coagulase test were also performed. Beta-lactamase production was studied by chromogenic methods. Methicillin resistance was phenotypically studied by the MRSA slide latex agglutination test, growth in MRSA agar, and the Vitek 2 and Wider systems (based on oxacillin MIC), and genotypically studied by detection of the mecA gene by PCR.

RESULTS

The clumping factor test was negative in 35.3% of strains. All isolates were correctly identified to species level by the ATB32-Staph system. Species misidentification rates were 5.9%, 23.5% and 29.4% with the Crystal, the Vitek 2 and the Wider systems, respectively, mostly as Staphylococcus haemolyticus. Beta-lactamase was present in 11.8% of strains. Whereas 76.5% and 47.1% of strains exhibited oxacillin resistance (MIC range 0.5-2 mg/L) by the Vitek 2 system and the Wider system, respectively, none of the strains was positive in the MRSA slide latex agglutination test or grew in MRSA agar. All strains lacked the mecA gene.

CONCLUSIONS

The clumping factor test and some commercial systems may misidentify S. lugdunensis. Oxacillin resistance detected by commercial systems is not indicative of the presence of the mecA gene. These facts, together with beta-lactamase production, may preclude adequate treatment of infections by this virulent coagulase-negative Staphylococcus.

Characterization of the fibrinogen-binding surface protein Fbl of Staphylococcus lugdunensis

The fbl gene of Staphylococcus lugdunensis encodes a protein Fbl that is 58 % identical to the clumping factor A (ClfA) of Staphylococcus aureus. The fbl gene was present in eight clinical isolates of S. lugdunensis. When Fbl was expressed on the surface of Lactococcus lactis it promoted adherence to immobilized fibrinogen and cell clumping in a fibrinogen solution. Purified recombinant Fbl region A bound to immobilized fibrinogen in a dose-dependent manner and inhibited the adherence of both Fbl-expressing and ClfA-expressing strains of L. lactis to fibrinogen. Adherence of S. lugdunensis and L. lactis Fbl(+) to immobilized fibrinogen was also inhibited by rabbit anti-Fbl region A antibodies and rabbit anti-ClfA region A antibodies, as well as by human immunoglobulin with a high level of anti-ClfA antibodies. Alignment of the A domains of CflA and Fbl revealed that all of the ClfA residues implicated in binding to the gamma-chain of fibrinogen are conserved in Fbl. Nevertheless Fbl had a tenfold lower affinity for fibrinogen, suggesting that sequence differences that occur elsewhere in the protein, possibly in beta-strand E of domain N2, affect ligand binding.

Molecular identification of Staphylococcus lugdunensis in a patient with meningitis

A 12-year-old child developed meningitis 6 days after a third ventriculostomy by endoscopy. A coagulase-negative Staphylococcus sp. was isolated in pure culture from the cerebrospinal fluid and was definitely identified as Staphylococcus lugdunensis after the 16S ribosomal DNA gene and rpoB gene were sequenced. This report describes the first case of S. lugdunensis meningitis.

Distribution of Staphylococcus sciuri subspecies among human clinical specimens, and profile of antibiotic resistance

The distribution of three subspecies comprising Staphylococcus sciuri was determined for a collection of 30 clinical isolates originating from Morocco, the United Kingdom, and France. The sources of these isolates were principally wounds, skin, and soft tissue infections. At the species level, the isolates were identified according to biochemical characteristics and at the subspecies level by the ribotyping technique. PCR analysis performed with the 16S-23S ribosomal DNA intergenic spacer was less powerful for subspecies differentiation. S. sciuri subsp. sciuri was the most frequent subspecies (21 isolates) found in the collection, whereas S. sciuri subsp. rodentium (seven isolates) and S. sciuri subsp. carnaticus (two isolates) were less common. mecA or a mecA-related gene was detected by PCR and Southern blot in all 30 S. sciuri isolates, supporting the suggestion that S. sciuri species are the natural reservoir of the mecA gene. While the linA/linA' gene coding for lincomycin resistance was present in five isolates, an uncharacterized gene for this resistance was suspected in seventeen other isolates.

Case of Staphylococcus schleiferi endocarditis and a simple scheme to identify clumping factor-positive staphylococci

Staphylococcus schleiferi is a coagulase-negative staphylococcus infrequently reported as a human pathogen. We report a case of prosthetic valve endocarditis attributed to this organism, contrast it to another Staphylococcus species that gives similar clumping factor results (S. lugdunensis), and propose a simple, effective identification scheme for identification of clumping factor-positive staphylococci.