Staphylococcus lugdunensis is a gram-positive, coagulase-negative organism, typically found in the normal skin flora, predominantly colonizing the perineal region. It has gained recognition as an opportunistic pathogen capable of causing severe infections. This manuscript presents a case study of a 75-year-old female with multiple comorbidities, including hypertension, hyperlipidemia, atrial fibrillation on Xarelto, type 2 diabetes mellitus, hypothyroidism, and a bioprosthetic aortic valve. The patient exhibited symptoms of fever, chills, and lethargy following a dog scratch that resulted in wounds on the left lower extremity. Despite initial negative findings in the drug screen and unremarkable workup for other infectious etiologies, the patient\'s clinical course revealed the presence of S. lugdunensis in the blood cultures. Timely intervention with broad-spectrum intravenous antibiotics and a six-week course of cefazolin led to significant improvement without recurrence. Staphylococcus lugdunensis, previously considered a relatively benign microorganism, has become a significant player in infectious diseases, particularly causing skin and soft tissue infections and infective endocarditis (IE). It is considered an aggressive pathogen, especially in chronic immunocompromised personnel, with a high potential for morbidity and mortality. S. lugdunensis was found to be the fourth most common cause of IE. The manuscript discusses the epidemiology, clinical presentation, and management of S. lugdunensis infections, emphasizing the importance of early recognition and treatment to prevent potentially fatal outcomes.

Cryoglobulinemic vasculitis and acute disseminated encephalomyelitis (ADEM) are characterized by damage to either blood vessels or grey matter. For both diseases, infections can be an etiology. In cryoglobulinemic vasculitis, the initial insult causes damage to the glomerulus, and in the case of ADEM, damage leads to a central nervous system demyelinating disorder. Infective endocarditis can be associated with both diseases and can be challenging to diagnose. Individuals on antibiotics may present with negative blood cultures, making underlying infective endocarditis difficult to diagnose. In this report, we describe a 21-year-old male who presented to the hospital after an assault with splenic laceration and was subsequently found to have infective endocarditis associated with cryoglobulinemic vasculitis and ADEM.

Biofilms make it difficult to eradicate bacterial infections through antibiotic treatments and lead to numerous complications. Previously, two periprosthetic infection-related pathogens, Enterococcus faecalis and Staphylococcus lugdunensis were reported to have relatively contrasting biofilm-forming abilities. In this study, we examined the proteomics of the two microorganisms\' biofilms using LC-MS/MS. The results showed that each microbe exhibited an overall different profile for differential gene expressions between biofilm and planktonic cells as well as between each other. Of a total of 929 proteins identified in the biofilms of E. faecalis, 870 proteins were shared in biofilm and planktonic cells, and 59 proteins were found only in the biofilm. In S. lugdunensis, a total of 1125 proteins were identified, of which 1072 proteins were found in common in the biofilm and planktonic cells, and 53 proteins were present only in the biofilms. The functional analysis for the proteins identified only in the biofilms using UniProt keywords demonstrated that they were mostly assigned to membrane, transmembrane, and transmembrane helix in both microorganisms, while hydrolase and transferase were found only in E. faecalis. Protein-protein interaction analysis using STRING-db indicated that the resulting networks did not have significantly more interactions than expected. GO term analysis exhibited that the highest number of proteins were assigned to cellular process, catalytic activity, and cellular anatomical entity. KEGG pathway analysis revealed that microbial metabolism in diverse environments was notable for both microorganisms. Taken together, proteomics data discovered in this study present a unique set of biofilm-embedded proteins of each microorganism, providing useful information for diagnostic purposes and the establishment of appropriately tailored treatment strategies. Furthermore, this study has significance in discovering the target candidate molecules to control the biofilm-associated infections of E. faecalis and S. lugdunensis.

Recently, a novel cyclo-heptapeptide composed of alternating D,L-amino acids and a unique thiazolidine heterocycle, called lugdunin, was discovered, which is produced by the nasal and skin commensal Staphylococcus lugdunensis. Lugdunin displays potent antimicrobial activity against a broad spectrum of Gram-positive bacteria, including challenging-to-treat methicillin-resistant Staphylococcus aureus (MRSA). Lugdunin specifically inhibits target bacteria by dissipating their membrane potential. However, the precise mode of action of this new class of fibupeptides remains largely elusive. Here, we disclose the mechanism by which lugdunin rapidly destabilizes the bacterial membrane potential using an in vitro approach. The peptide strongly partitions into lipid compositions resembling Gram-positive bacterial membranes but less in those harboring the eukaryotic membrane component cholesterol. Upon insertion, lugdunin forms hydrogen-bonded antiparallel β-sheets by the formation of peptide nanotubes, as demonstrated by ATR-FTIR spectroscopy and molecular dynamics simulations. These hydrophilic nanotubes filled with a water wire facilitate not only the translocation of protons but also of monovalent cations as demonstrated by voltage-clamp experiments on black lipid membranes. Collectively, our results provide evidence that the natural fibupeptide lugdunin acts as a peptidic channel that is spontaneously formed by an intricate stacking mechanism, leading to the dissipation of a bacterial cell\'s membrane potential.

UNASSIGNED: Staphylococcus lugdunensis (S lugdunensis) is a coagulase-negative staphylococcus species that has been increasingly recognized to cause serious infections with virulence resembling Staphylococcus aureus (S aureus). No studies have evaluated the characteristics and outcomes of patients with S lugdunensis peritoneal dialysis-related peritonitis compared with those with S aureus peritonitis. We aim to evaluate the clinical course of peritonitis as caused by these organisms.
UNASSIGNED: A retrospective matched comparative analysis involving a single tertiary center from July 2000 to July 2020.
UNASSIGNED: Forty-eight episodes of S aureus peritonitis were matched to 19 cases of S lugdunensis peritonitis.
UNASSIGNED: The cases were individually matched for year of peritonitis, sex, age (±10 years), and Charlson Comorbidity Index (±3). A comparative analysis was performed between the 2 organisms. The outcome includes responses at day 5 of peritonitis and the rate of complete response.
UNASSIGNED: There is a higher predilection of diabetes in those with S aureus peritonitis than in those with S lugdunensis (64.6% vs 31.6%; P = 0.03). Patients with S aureus peritonitis also have a much higher total cell count at presentation (4,463.9 ± 5,479.5 vs 1,807.9 ± 3,322.7; P = 0.05); a higher prevalence of poor response at day 5 (50.0% vs 15.8%; P = 0.03); a lower rate of complete response (64.6% vs 94.7%; P = 0.01) and are more prone to relapse with the same organism (29.2% vs 0%, respectively; P = 0.01) as compared to those with S lugdunensis.
UNASSIGNED: The result of this small retrospective study involving a single center may not be generalizable to other centers. There is also no data for comparative analysis on other coagulase-negative staphylococci such as Staphylococcus epidermidis, which belongs to the same family as S lugdunensis.
UNASSIGNED: Although S aureus peritonitis is more virulent with significant morbidity, S lugdunensis can cause similarly serious peritonitis. This largest case series of S lugdunensis peritonitis enabled better characterization of clinical features and outcomes of patients with S lugdunensis peritonitis.
Staphylococcus lugdunensis is a coagulase-negative staphylococcus species that has been increasingly recognized to cause serious infections with virulence resembling Staphylococcus aureus. No studies have evaluated the characteristics and outcomes of patients with S lugdunensis peritoneal dialysis-related peritonitis compared those with S aureus peritonitis. This largest retrospective matched comparative analysis of S lugdunensis peritonitis enabled better characterization of clinical features and outcomes of patients with S lugdunensis. Our result suggested that although S. aureus peritonitis is more virulent with significant morbidity, S lugdunensis can cause similarly serious peritonitis. Regardless, S lugdunensis remains susceptible to most antibiotics and penicillin group, penicillin G in particular, can be considered as the first line antibiotic.

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.

Background Staphylococcus lugdunensis is a pathogen that can cause various diseases in humans, of which bacteremia and infective endocarditis have been described most extensively. In Saudi Arabia, reports of S. lugdunensis infection are extremely rare, and no studies have reported S. lugdunensis antibiotic susceptibility. The objective of this study was to determine S. lugdunensis clinical disease, potential risk factors, susceptibility pattern, and 30-day mortality. Methods A retrospective study was performed at King Abdulaziz University Hospital in Jeddah, Saudi Arabia, from January 1, 2015, to December 31, 2022. Patients ≥14 years old were included. All variables, such as age, sex, body mass index (BMI), clinical manifestations, source of infection, antimicrobial susceptibility, antimicrobial given, duration of treatment, and 30-day mortality, were obtained from electronic health charts. Results Twenty-five patients with S. lugdunensis infection were identified, with a median age of 58 years and all had comorbidities (mean: 2, range 1-10). The patients had a median BMI of 28, and most patients were either overweight (28%, n = 7) or obese (48%, n = 12). The 30-day mortality was only 8% (n = 2). S. lugdunensis was most often cultured from wound swabs (72%, n = 18) and blood (20%, n = 5). The majority (68%, n = 17) of infections were community-acquired. Antibiotic susceptibility to vancomycin was 100% (n = 25), oxacillin 72% (n = 18), and clindamycin and trimethoprim-sulfamethoxazole 64% (n = 16) each. The mean Charlson comorbidity index was significantly higher (p-value = 0.027) among the deceased patients (6.00 ± 2.12) than those that survived (1.83 ± 1.77). Conclusion S. lugdunensis can cause clinically significant disease, especially in patients with multiple comorbidities, and a higher Charlson comorbidity index was found in patients who died.

OBJECTIVE: Our previous studies showed that lugdunin activities are associated with Staphylococcus lugdunensis genotypes, and most isolates do not exhibit lugdunin activity. As a continuation of our previous analysis, we focused on the reasons for defects in lugdunin production in S. lugdunensis clinical isolates.
METHODS: A comparative analysis of 36 S. lugdunensis whole genome sequencing data revealed three major mutation types, unknown deletion mechanism that caused most of lug operon genes lost, mobile genetic element (MGE) insertion, and nonsense mutations, which potentially damaged lugdunin production. A total of 152 S. lugdunensis clinical isolates belonging to lugdunin nonproducers were further examined for the above three mutation types. PCR products were sequenced to examine these variations.
RESULTS: Forty-six of the 152 isolates were CRISPR-Cas IIC isolates, including 26 ST27, 14 ST4, and 6 ST29 isolates; further investigation confirmed that all of their lug operons had lost almost all lug operon genes except lugM. An IS256 insertion in lugA was identified in 16 isolates, and most isolates (15 over 16) belonged to ST3. In addition, three nonsense mutations caused by single nucleotide substitutions (an adenine deletion in lugB at the 361th and 1219th nucleotides and an adenine deletion in lugC at the 1612nd nucleotide) that were frequently observed among 36 S. lugdunensis whole genome sequencing data were further observed in our clinical isolates. These three nonsense mutations were frequently found in most of CRISPR-Cas IIIA strains, especially in ST6 isolates.
CONCLUSIONS: Our findings suggest that the mechanisms affecting lugdunin production are associated with S. lugdunensis molecular types.

The haloacid dehalogenase superfamily implicated in bacterial pathogenesis comprises different enzymes having roles in many metabolic pathways. Staphylococcus lugdunensis, a Gram-positive bacterium, is an opportunistic human pathogen causing infections in the central nervous system, urinary tract, bones, peritoneum, systemic conditions and cutaneous infection. The haloacid dehalogenase superfamily proteins play a significant role in the pathogenicity of certain bacteria, facilitating invasion, survival, and proliferation within host cells. The genome of S. lugdunensis encodes more than ten proteins belonging to this superfamily. However, none of them have been characterized. The present work reports the characterization of one of the haloacid dehalogenase superfamily proteins (SLHAD1) from Staphylococcus lugdunensis. The functional analysis revealed that SLHAD1 is a metal-dependent acid phosphatase, which catalyzes the dephosphorylation of phosphorylated metabolites of cellular pathways, including glycolysis, gluconeogenesis, nucleotides, and thiamine metabolism. Based on the substrate specificity and genomic analysis, the physiological function of SLHAD1 in thiamine metabolism has been tentatively assigned. The crystal structure of SLHAD1, lacking 49 residues at the C-terminal, was determined at 1.7 Å resolution with a homodimer in the asymmetric unit. It was observed that SLHAD1 exhibited time-dependent cleavage at a specific point, occurring through a self-initiated process. A combination of bioinformatics, biochemical, biophysical, and structural studies explored unique features of SLHAD1. Overall, the study revealed a detailed characterization of a critical enzyme of the human pathogen Staphylococcus lugdunensis, associated with several life-threatening infections.

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