Late Periprosthetic Joint Infection due to Staphylococcus lugdunensis Identified by Matrix-Assisted Laser Desorption/Ionisation Time of Flight Mass Spectrometry: A Case Report and Review of the Literature

Staphylococcus lugdunensis, member to the group of coagulase-negative staphylococci, is previously thought to be rarely isolated. Recently other staphylococci have been described, which were supposedly related to S. lugdunensis, such as Staphylococcus pseudolugdunensis and Staphylococcus pettenkoferi. To decrease the rate misidentifications, an accurate identification method, such as matrix-assisted laser desorption ionization time of flight mass spectrometry or molecular methods, should be used. S. lugdunensis is usually associated with severe infections similar to those caused by S. aureus. Moreover, it has been described that skin infections due to S. lugdunensis are severely underreported and could be also underreported in periprosthetic joint infections. Ours is the first case of a late periprosthetic infection of the hip due to S. lugdunensis, identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. A periprosthetic infection due to S. lugdunensis should be treated according to protocols of S. aureus periprosthetic infections, and therefore an accurate species identification is desirable

Occurrence of genes of putative fibrinogen binding proteins and hemolysins, as well as of their phenotypic correlates in isolates of S. lugdunensis of different origins

<p>Abstract</p> <p>Background</p> <p><it>Staphylococcus lugdunensis </it>is an important human pathogen that causes potentially fatal endocarditis, osteomyelitis and skin and soft tissue infections similar to diseases caused by <it>Staphylococcus aureus</it>. Nevertheless, in contrast to <it>S. aureus</it>, data on pathogenicity factors of <it>S. lugdunensis </it>is scarce. Two adhesins, a fibrinogen and a von Willebrand factor binding protein, and a <it>S. lugdunensis </it>synergistic hemolysin (SLUSH) have been previously described. Moreover, the newly sequenced genome of <it>S. lugdunensis </it>revealed genes of other putative fibrinogen binding adhesins and hemolysins. The aim of this study was to gain more insight into the occurrence of genes likely coding for fibrinogen binding adhesins and hemolysins using clinical strains of <it>S. lugdunensis</it>.</p> <p>Findings</p> <p>Most of the putative adhesin genes and hemolysin genes investigated in this study were highly prevalent, except for the SLUSH gene cluster. In contrast to previous reports, binding to fibrinogen was detected in 29.3% of the <it>S. lugdunensis </it>strains. In most strains, hemolysis on blood agar plates was weak after 24 h and distinct after 48 h of incubation. The fibrinogen binding and hemolysis phenotypes were also independent of the type of clinical specimen, from which the isolates were obtained.</p> <p>Conclusion</p> <p>In this study we described a pyrrolidonyl arylamidase negative <it>S. lugdunensis </it>isolate. Our data indicate that a matrix-assisted laser desorption ionisation time-of-flight MS-based identification of <it>S. lugdunensis </it>or species-specific PCR's should be performed in favour of pyrrolidonyl arylamidase testing. In contrast to the high occurrence of putative fibrinogen binding protein genes, 29.3% of the <it>S. lugdunensis </it>strains bound to fibrinogen. Putative hemolysin genes were also prevalent in most of the <it>S. lugdunensis </it>strains, irrespective of their hemolysis activity on Columbia blood agar plates. Similar to a previous report, hemolysis after 48 h of incubation is also indicative for <it>S. lugdunensis</it>. The SLUSH gene cluster was detected in an estimated 50% of the strains, indicating that this locus is different or non-prevalent in many strains.</p

Transport of D-serine and tetracycline resistance in Staphylococcus saprophyticus\textit {Staphylococcus saprophyticus} as well as binding of fibrinogen and fibronectin in Staphylococcus lugdunensis\textit {Staphylococcus lugdunensis}

$\textit {Staphylococcus saprophyticus}$ ist ein Harnwegspathogen. Es spaltet die im Urin vorkommende Amminosäure D-Serin, welche auf andere nicht-uropathogene Bakterien toxisch wirkt, zu Pyruvat und Ammonium. In dieser Arbeit wurde SSP1070 als ein D-Serintransporter in $\textit {S. saprophyticus}$ identifiziert und mindestens ein weiterer D-Serintransporter postuliert. Des Weiteren wurde gezeigt, dass ca. 10% aller $\textit {S. saprophyticus}$ Stämme Tetracyclin-resistent sind. Die Resistenzdeterminante ist $\it tet$K, welches sich auf pT181-ähnlichen Plasmiden befindet. $\textit {Staphylococcus lugdunensis}$ ist ein häufiger Vertreter der menschlichen Hautflora und verursacht ähnliche Erkrankungen wie $\textit {Staphylococcus aureus}$. In dieser Arbeit wurde zum ersten Mal die Transformation und genetische Manipulation dieser Spezies beschrieben. Dabei wurden Mutanten des $\it fbl$-gens erzeugt und charakterisiert. Fibrinogen- und Fibronektinbindungseigenschaften sind heterogen innerhalb der Spezies verteilt

Response of Human Macrophages to Clinically Applied Wound Dressings Loaded With Silver

Wound infections constitute an increasing clinical problem worldwide. To reverse this trend, several wound dressings with antimicrobial properties have been developed. Considering the increasing presence of antibiotic-resistant microorganisms, product developers have been focusing their efforts in introducing antibiotic-free antibacterial wound dressings to the market, with silver being the most commonly incorporated antimicrobial agent. In this scenario, gaining information about the microbial and eukaryotic cells’ response to these dressings is needed for a proper selection of antimicrobial dressings for the different cases of infected wounds. In particular, one insufficiently explored parameter is the effect of the dressings on the immunomodulation of macrophages, the main immune cell population participating in the repair process, because of their pivotal role in the transition of the inflammation to the proliferation phase of wound healing. In this work, three different clinically applied antimicrobial, silver impregnated wound dressings were selected: Atrauman® Ag, Biatain® Alginate Ag and PolyMem WIC Silver® Non-adhesive. Antimicrobial susceptibility tests (disk diffusion and broth dilution), cell viability evaluation (CellTiter-Blue®) and experiments to determine macrophage polarization (e.g., flow cytometry, ELISA and glucose uptake) were performed after 24 h of incubation. Among all products tested, Biatain® Alginate Ag induced the most evident bactericidal effect on Gram-positive and Gram-negative bacteria, followed by PolyMem WIC Silver® Non-adhesive, but did not show good cytocompatibility in vitro. On the other hand, Atrauman® Ag showed excellent cytocompatibility on L929 fibroblasts, HaCaT keratinocytes and THP-1 derived macrophages, but no significant antimicrobial activity was observed. Overall, it was confirmed that macrophages initiate, in fact, an alteration of their metabolism and phenotype in response to wound dressings of different composition in a short period of contact (24 h). M0 resting state macrophages common response to all silver-containing dressings used in this study was to increase the production of the anti-inflammatory cytokine TGF-β, which indicates an acquisition of M2-like macrophages characteristics

First description of <it>Escherichia coli</it> producing CTX-M-15- extended spectrum beta lactamase (ESBL) in out-patients from south eastern Nigeria

<p>Abstract</p> <p>We studied the presence of extended spectrum beta lactamases (ESBLs) in 44 clinical isolates of <it>Escherichia coli</it> collected from out-patients in two university teaching hospitals in South-Eastern Nigeria. Species identification was performed by standard microbiology methods and re-confirmed by MALDI-TOF technology. Phenotypic characterization of ESBL enzymes was done by double disc synergy test and presence of ESBL genes was determined by specific PCR followed by sequencing. Transfer of plasmid DNA was carried out by transformation using <it>E. coli</it> DH5 as recipient strain. Phenotypic characterization identified all isolates to be ESBL positive. 77% of strains were from urine, 13.6% from vaginal swabs and 9.0% from wound swabs. 63.6% were from female patients, 68% were from outpatients and 95.5% from patients younger than 30 years. All ESBL producers were positive in a PCR for <it>bla</it>_CTX-M-1 cluster, in exemplary strains <it>bla</it>_CTX-M-15 was found by sequencing. In all strains IS<it>Ecp1</it> was found upstream and ORF477 downstream of <it>bla</it>_CTX-M. PCR for <it>bla</it>_TEM and <it>bla</it>_OXA-1 was positive in 93.1% of strains, whereas <it>bla</it>_SHV was not detected, aac(6′)-Ib-cr was found in 97.7% of strains. RAPD analysis revealed seven different clonal groups named A through G with the majority of the strains (65.9%) belonging to clone A. Transfer of an ESBL plasmid with co-resistance to gentamicin, kanamycin, tobramycin, doxycycline and trimethropim-sulfamethoxazole was successful in 19 (43.2%) strains. This study showed a high rate of CTX-M-1 cluster - ESBLs in South-Eastern Nigeria and further confirms the worldwide spread of CTX-M ESBL in clinical isolates.</p

The major autolysin of Staphylococcus lugdunensis, AtlL, is involved in cell separation, stress-induced autolysis and contributes to bacterial pathogenesis

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