Staphylococcus lugdunensis: antimicrobial susceptibility and optimal treatment options

Staphylococcus lugdunensis Peritoneal Dialysis-Related Peritonitis: A Matched Comparative Analysis

Rationale & Objective

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.

Study Design

A retrospective matched comparative analysis involving a single tertiary center from July 2000 to July 2020.

Setting & Participants

Forty-eight episodes of S aureus peritonitis were matched to 19 cases of S lugdunensis peritonitis.

Analytical Approach

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.

Results

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.

Limitations

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.

Conclusions

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.

The Deadly Contaminant: A Case of Staphylococcus lugdunensis Endocarditis

The incidence of infective endocarditis (IE) has been on the rise since it was first reported a century ago, and the associated mortality remains unchanged despite advances in medical and surgical management. To diagnose IE, the modified Duke criteria are used, which rely on isolating the causative organism. However, this can be challenging if the micro-organism is considered a contaminant. Staphylococcus lugdunensis (SL) is one such organism. In this case, an elderly female presented with intermittent chest pain, palpitation, and diaphoresis, for which she underwent left heart catheterization. Her hospital course was complicated by persistent fever and night sweats, leading to blood cultures isolating methicillin sensitivity. It was initially reported as a contaminant. However, an extensive workup was unremarkable, and a transthoracic echocardiogram was done, which revealed tricuspid vegetations with moderate regurgitation. The patient was treated with cefazolin, repeat cardiac imaging at the end of treatment revealed no vegetation, and the patient remained asymptomatic. Despite being associated with fulminant IE with higher mortality than Staphylococcus aureus (S. aureus), which requires surgical management in most cases, SL is still often reported as a contaminant. Isolation of SL should warrant further investigation beyond mere contaminants, and prompt treatment should be initiated in the appropriate clinical scenario to avoid poor outcomes.

Searching for Virulence Factors among Staphylococcus lugdunensis Isolates from Orthopedic Infections: Correlation of β-hemolysin, hemolysin III, and slush Genes with Hemolytic Activity and Synergistic Hemolytic Activity

Staphylococcus lugdunensis is an emerging high-virulent pathogen. Here, the presence and expression of virulence genes (icaA, fbl, vwbl, fbpA, slush A, B and C, and genes of the putative β-hemolysin and hemolysin III) and the ability to induce synergistic hemolytic activity and hemolysis after 24, 48 and 72 h were investigated in a collection of twenty-two S. lugdunensis clinical isolates. The collection of isolates, mainly from implant orthopedic infections, had previously been grouped by ribotyping/dendrogram analysis and studied for biofilm matrices, biomasses and antibiotic resistances. Two isolates, constituting a unique small ribogroup sharing the same cluster, exhibited an amplicon size of the slush operon (S. lugdunensis synergistic hemolysin) which was shorter than the expected 977 bp. This outcome can predict the genetic lineage of the S. lugdunensis strains. One isolate (cra1342) presented two deletions: one of 90 bp in slush A and the other of 91 bp in slush B. Another isolate (N860314) showed a single 193 bp deletion, which encompassed part of the slush B terminal sequence and most of slush C. The isolate N860314 was devoid of hemolytic activity after 24 h, and the first consideration was that the deleted region deals with the coding of the active enzymatic site of the slush hemolysin. On the other hand, cra1342 and N860314 isolates with different slush deletions and with hemolytic activity after 24 and 48 h, respectively, could have replaced the hemolytic phenotype through other processes.

From Obscurity To Spotlight: Staphylococcus lugdunensis-Induced Infective Endocarditis, a Profound Case Unraveling

Infective endocarditis (IE) represents a grave infection characterized by endocardial inflammation and valve impairment due to diverse pathogens. Staphylococcus lugdunensis, a coagulase-negative organism, has garnered increasing recognition as a significant etiological agent of IE. This bacterium is renowned for its aggressive tissue infections encompassing bone and joint, bloodstream, and IE sites. Particularly noteworthy is the rapid devastation and abscess formation it induces on heart valves, resulting in elevated mortality rates. The pathogen's affinity for von Willebrand factor facilitates its attachment to cardiac valves and blood vessels, thereby exacerbating its virulence. This abstract provides a comprehensive overview of S. lugdunensis-triggered IE. We present a compelling case involving a 66-year-old female afflicted by IE attributed to this microorganism, illuminating the clinical manifestations and challenges linked to the ailment. Moreover, we scrutinize previously reported instances of S. lugdunensis-related IE spanning from 1993 to 2022, accentuating the escalating importance of this pathogen in disease causality. The deleterious consequences of S. lugdunensis-induced IE emanate from its distinctive clinical attributes, necessitating tailored diagnostic strategies and treatment considerations. Given the gravity and swift progression of the infection, healthcare professionals play a pivotal role in administering timely and efficacious management for afflicted patients. Further research is imperative to enhance diagnostic modalities and explore therapeutic approaches aimed at effectively combating this formidable and life-threatening infection.

Trends in coagulase-negative staphylococci (CoNS), England, 2010-2021

Objective

To review the epidemiology of coagulase-negative staphylococci (CoNS) in England over the recent 12 year period.

Methods

Laboratory-confirmed CoNS reported from sterile sites in patients in England to the UK Health Security Agency (UKHSA) between 2010 and 2021 were extracted from the national laboratory database and analysed.

Results

Overall, 668 857 episodes of CoNS were reported. Unspeciated CoNS accounted for 56 % (374 228) of episodes, followed by Staphylococcus epidermidis (26 %; 174 050), S. hominis (6.5 %; 43 501) and S. capitis (3.9 %; 25 773). Unspeciated CoNS increased by 8.2 % (95 % CI, 7.1-9.3) annually between 2010 and 2016, then decreased annually by 6.4 % (95 % CI: -4.8 to -7.9) until 2021. Speciated CoNS increased by 47.6 % (95 % CI, 44.5-50.9) annually between 2010 and 2016 and increased annually by 8.9 % (95 % CI: 5.1 to 12.8) until 2021. Antimicrobial susceptibility profiles differed by species.

Conclusions

Reports of CoNS from normally sterile body sites in patients in England increased between 2010 and 2016 and remained stable between 2017 and 2021. There has been a striking improvement in species-level identification of CoNS in recent years. Monitoring trends in CoNS epidemiology is crucial for development of observational and clinical intervention studies on individual species.

Characteristics and outcomes in adult patients with Staphylococcus lugdunensis bacteremia compared to patients with Staphylococcus epidermidis and Staphylococcus aureus bacteremia: a retrospective study in a 16-year period at the university hospital, Japan

BACKGROUND

Staphyococcus lugudnensis (S. lugdunensis) is one of coagulase-negative Staphylococcus species with a potential to cause invasive infections. Few studies have evaluated the characteristics and outcomes of patients with S. lugdunensis bacteremia (SLB) compared with those of patients with Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus) bacteremia.

METHODS

We performed a single-center retrospective case-control study of patients aged ≥ 18 who had SLB with at least two sets of positive blood cultures at the Kyoto University Hospital, Japan, from January 2005 to June 2022. Patients who had S. epidermidis bacteremia (SEB) with at least two sets of positive blood cultures and those who had S. aureus bacteremia (SAB) with at least one set of positive blood cultures were randomly selected in a 1:5:5 (SLB:SEB:SAB) ratio.

RESULTS

A total of 22 patients with SLB, 110 patients with SEB, and 110 patients with SAB were included. The proportions of infective endocarditis (IE) and metastatic infections were statistically higher in the SLB group than in the SEB group (14% vs. 2%, p < 0.01 and 18% vs. 5%, p 0.02, respectively) and were not significantly different between the SLB and SAB groups (14% vs. 5%, p 0.16 and 18% vs. 16%, p 0.78, respectively). The seven-day mortality was higher in the SLB group than in the SEB group (9% vs. 1%, p 0.02) and similar between the SLB and SAB groups (9% vs. 7%, p 0.77).

CONCLUSIONS

The clinical course and outcome of SLB were worse than those of SEB and similar to those of SAB. Appropriate evaluation and treatment for SAB may be warranted in patients with SLB.

Characterization of oxacillin-resistant Staphylococcus lugdunensis isolated from sterile body fluids in a medical center in Taiwan: A 12-year longitudinal epidemiological study

BACKGROUND

In this study, our objective was to characterize Staphylococcus lugdunensis isolated from sterile body fluids (SBFs) in a medical center in Taiwan between 2009 and 2020.

METHODS

We used MALDI-TOF MS, disk diffusion testing, agar dilution assay, SCCmec typing, and antibiotic resistance gene screening to identify and investigate the characteristics of oxacillin-resistant S. lugdunensis (ORSL).

RESULTS

A total of 438 S. lugdunensis isolates were collected and 146 (33.3%) isolates were identified as ORSL. SCCmec type V was dominant (65.7%) in our ORSL isolates, followed by SCCmec type II (18.5%), and type IV (8.9%). After 2013, a slight increase in SCCmec types IV and V was revealed. Moreover, all ORSL isolates with type II and untypable SCCmec were highly resistant to oxacillin (MIC >32 μg/mL), compared to ORSL that had SCCmec types IV, V, and VT. All 146 ORSL isolates were resistant to penicillin and susceptible to teicoplanin and vancomycin. High resistance rates of ORSL to clindamycin (43.2%), erythromycin (43.2%), gentamicin (78.1%) and tetracycline (46.6%) was observed. Moreover, only two (1.4%) and six (4.1%) ORSL isolates were resistant to trimethoprim/sulfamethoxazole and ciprofloxacin, respectively. The erythromycin-resistant ORSL isolates mostly exhibited constitutive MLS_B resistant phenotype (61/63, 96.8%) and contained either ermC alone (27/63, 42.9%) or a combination of ermC with ermA (28/63, 44.4%).

CONCLUSION

Our present study showed a stable rate of ORSL from SBFs during 2009-2020. Moreover, teicoplanin, vancomycin, trimethoprim/sulfamethoxazole, and ciprofloxacin were shown to be highly efficient for the treatment of ORSL in vitro.

Staphylococcus lugdunensis Endophthalmitis Following Intravitreal Anti-vascular Endothelial Growth Factor Injections

Staphylococcus lugdunensis is a rare causative organism of endophthalmitis following intravitreal injections. It presents an aggressive disease course with potentially devastating outcomes. In this case, the patient presented late with a severely painful, red eye with a reduced visual acuity from 6/18 to light perception following bilateral intravitreal injections of anti-vascular endothelial growth factor. Strict adherence to the bilateral intravitreal injection protocol meant prevention of infection in the right eye. Intravitreal vancomycin was administered without delay and an emergency vitreous biopsy was performed, confirming S. lugdunensis as the causative organism. An intense course of oral and topical steroids was chosen due to the aggressiveness of this organism. Early vitreo-retinal opinion was sought but the patient was deemed not suitable for vitrectomy due to initial improvements in visual acuity to hand movements. The patient showed improvements in the visual acuity to 1/60, and remains on a weaning regime of oral and topical steroids with no further complications.

An lnu(A)-Carrying Multi-Resistance Plasmid Derived from Sequence Type 3 Methicillin-Resistant Staphylococcus lugdunensis May Contribute to Antimicrobial Resistance in Staphylococci

Methicillin-resistant Staphylococcus lugdunensis (MRSL) strains showing resistance to several common antibiotics have been reported recently. Sequence type (ST) 3 MRSL carrying SCCmec types IV, V, or Vt is the major lineage associated with health care-associated infections. We aimed to investigate the distribution and dissemination of antimicrobial resistance determinants in this lineage. Two representative ST3-MRSL strains, CGMH-SL131 (SCCmec V) and CGMH-SL138 (SCCmec IV), were subjected to whole-genome sequencing. Detection of antibiotic resistance genes and screening of susceptibility patterns were performed for 30 ST3-MRSL and 16 ST6-MRSL strains via PCR and standard methods. Except for mecA and blaZ, antimicrobial resistance genes were located within two plasmids: a 28.6 kb lnu(A)-carrying plasmid (pCGMH_SL138) in CGMH-SL138 and a 26 kb plasmid carrying non-lnu(A) resistance genes (pCGMH_SL131) in CGMH-SL131. Both plasmids shared common genetic features with multiple copies of IS257 flanked by genes conferring resistance to aminoglycoside (aacA-aphD and aadD), TET (tetk), and cadmium (cadDX) and tolerance to chlorhexidine (qacA/R); however, only pCGMH_SL138 harbored lnu(A) that conferred resistance to lincomycin and rep13 that encodes a replication initiation protein. Unlike ST6-MRSL, none of the ST3-MRSL isolates contained the ermA gene. Instead, most isolates harbored lnu(A) (20/30, 66.7%), and several other resistance genes found on pCGMH_SL138. These isolates and transformants containing pCGMH_SL138 exhibited susceptibility to ERY and higher MICs for lincomycin and aforementioned antibiotics. A novel lnu(A)-carrying plasmid, pCGMH_SL138, that harbored a multiresistance gene cluster, was identified in ST3-MRSL strains and may contribute to the dissemination of antibiotic resistance in staphylococci.

Antimicrobial Resistance and Antimicrobial Activity of Staphylococcus lugdunensis Obtained from Two Spanish Hospitals

Staphylococcus lugdunensis is a coagulase-negative-staphylococci (CoNS) that lately has gained special attention in public health as a human pathogen and also as a bacteriocin-producer bacteria. In this study, we characterized 56 S. lugdunensis isolates recovered from human samples in two Spanish hospitals. Antimicrobial susceptibility testing was performed and antimicrobial resistance and virulence genotypes were determined. Antimicrobial activity (AA) production was evaluated by the spot-on-lawn method against 37 indicator bacteria, including multidrug-resistant (MDR) isolates, and the presence of the lugD gene coding for lugdunin bacteriocin was analyzed by PCR. The antibiotic resistance detected was as follows (% resistance/genes detected): penicillin (44.6%/blaZ), oxacillin (1.8%/mecA on SCCmec-V), erythromycin-clindamycin inducible (7.1%/erm(C), msrA), tetracycline (5.3%/tetK), gentamicin and/or tobramycin (3.6%/ant(4′)-Ia, acc(6′)-aph(2″)), and fosfomycin (21.4%). A MDR phenotype was detected in 5% of isolates. Twenty-one of the S. lugdunensis isolates showed susceptibility to all 20 antibiotics tested (37.5%). The screening for AA revealed 23 antimicrobial producer (AP) isolates with relevant inhibition against coagulase-positive-staphylococci (CoPS), including both methicillin-susceptible and –resistant S. aureus. The lugD gene was detected in 84% of the 56 S. lugdunensis isolates. All of the AP S. lugdunensis isolates (n = 23) carried the lugD gene and it was also detected in 24 of the non-AP isolates, suggesting different gene expression levels. One of the AP isolates stood out due to its high antimicrobial activity against more than 70% of the indicator bacteria tested, so it will be further characterized at genomic and proteomic level.

May Staphylococcus lugdunensis Be an Etiological Factor of Chronic Maxillary Sinuses Infection?

Staphylococcus lugdunensis is an opportunistic pathogen found in the healthy human skin microbiome bacterial community that is able to cause infections of diverse localization, manifestation, and course, including laryngological infections, such as necrotizing sinusitis. Chronic maxillary sinusitis is a disease present in up to one third of European and American populations, and its etiology is not fully described. Within this study, we aimed to characterize 18 S. lugdunensis strains recovered from maxillary sinuses and evaluate them as etiological agents of chronic disease. We performed MLST analysis, the complex analysis of both phenotypic and genetic virulence factors, antibiotic susceptibility profiles, and biofilm formation assay for the detection of biofilm-associated genes. Altogether, S. lugdunensis strains were clustered into eight different STs, and we demonstrated several virulence factors associated with the chronic disease. All tested strains were able to produce biofilm in vitro with numerous strains with a very strong ability, and overall, they were mostly susceptible to antibiotics, although we found resistance to fosfomycin, erythromycin, and clindamycin in several strains. We believe that further in-depth analysis of S. lugdunensis strains from different niches, including the nasal one, should be performed in the future in order to reduce infection rate and broaden the knowledge about this opportunistic pathogen that is gaining attention.

Staphylococcus lugdunensis Urinary Tract Infection With Associated Neutropenic Fever

We present a 62-year-old woman with a history of uterine cancer status post-total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH-BSO) on paclitaxel, who presented to the emergency department febrile at 101.7 Fahrenheit and complaining of fatigue and urinary incontinence. Laboratory testing revealed neutropenia and urinalysis showed elevated bacteria with minimal white blood cells, and negative leukocyte and negative nitrites. Urine cultures ultimately showed Staphylococcus lugdunensis with negative blood cultures.

S. lugdunensis is a less frequently speciated Staphylococcus and has been increasingly found due to advances in identification using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). S. lugdunensis are Gram-positive cocci, nonsporulating, nonmotile, facultatively anaerobic, catalase-positive, coagulase-negative, oxidase-negative, delta-hemolytic organism. Traditionally, it is seen in skin and soft-tissue infections, as well as vascular infections, however, has minimal occurrences in urinary tract infections.

The risk of infection is increased in immunocompromised states and empiric treatment is warranted while waiting for definitive results. Our patient was started on cefepime, valacyclovir, fluconazole, and a single dose of vancomycin while in the emergency department. Worsening thrombocytopenia during her antibiotic course necessitated the re-evaluation of antibiotic agents which can cause thrombocytopenia. Subsequently, due to the patient’s improved clinical status, and low risk of severe outcome, fluconazole and valacyclovir were discontinued, and cefepime was changed to ceftriaxone.

Comparative Genomic Analyses Reveal Potential Factors Responsible for the ST6 Oxacillin-Resistant Staphylococcus lugdunensis Endemic in a Hospital

Oxacillin-resistant Staphylococcus lugdunensis (ORSL) is considered a life-threatening isolate in healthcare settings. Among ORSL clones, ST6-SCCmec II strains are associated with an endemic spread in hospitals. We analyzed the complete genome of ORSL CGMH-SL118, a representative strain. Results revealed that this strain contained three MGEs (two prophages and one plasmid) other than the SCCmec II element, which showed remarkable differences in genome organization compared to the reference strains from NCBI. Eight multidrug-resistant genes were identified. All but blaZ were carried by MGEs, such as the SCCmec II element [mecA, ant (9)-Ia, and ermA] and the prophage φSPbeta [aac (6')-aph (2'), aph (3')-III, and ant (6)-Ia], indicating that MGEs carrying multidrug-resistant genes may be important for ST6 strains. The prophage φSPbeta contains sasX gene, which was responsible for the pathogenesis of Staphylococcus aureus. A phage-mediated resistant island containing fusB (SlRI_fusB-118) was found near φSPbeta, which was highly homologous to type III SeRI_fusB-5907 of Staphylococcus epidermidis. In contrast to previous studies, over 20% of ST6 isolates showed a fusidic acid-resistant phenotype, suggesting that phage-mediated intraspecies transmission of resistant islands may become an important issue for ST6 strains. Sixty-eight clinical isolates of ST6 Staphylococcus lugdunensis (50 OSSL, oxacillin-sensitive S. lugdunensis, and 18 ORSL, including CGMH-SL118) collected from various types of specimens in the hospital were studied. Among these isolates in this study, ORSL showed similar drug-resistant genes and phenotypes as CGMH-SL118. The comparative genomic analyses highlight the contribution of MGEs in the development and dissemination of antimicrobial resistance in ST6 strains, suggesting that resistance determinants and virulence factors encoded by MGEs provide a survival advantage for successful colonization and spread in healthcare settings.

Staphylococcus lugdunensis as Cause of Septic Pericarditis

Staphylococcus lugdunensis (S. lugdunensis) is a coagulase-negative gram-positive bacterium, considered part of skin flora, which can simultaneously cause human diseases. S. lugdunensis has been reported in the literature as one of the causative agents for infective endocarditis.1 Although one of the coagulasenegative staphylococci, S. lugdunensis shares many virulent characteristics with Staphylococcus aureus (S. aureus), including biofilm formation. It has been associated with various foreign body-related infections such as prosthetic joint infections,2 in addition to bacteremia, osteomyelitis, septic arthritis, central nervous system, urinary tract infections, peritonitis, infective endocarditis and others. Given the association with severe and aggressive infections, it is important to treat S. lugdunensis as true infection rather than a contaminant, particularly in a suspect clinical context.3-6 Currently, there are no reported cases in the literature on pericarditis secondary to S. lugdunensis. We present a case of a 69-year-old woman with pericarditis, sepsis and disseminated intravascular coagulopathy (DIC) due to S. lugdunensis.

Antimicrobial Susceptibility Testing for Staphylococcus lugdunensis

Evaluation of penicillin and oxacillin susceptibility testing was conducted on two hundred Staphylococcus lugdunensis isolates. Disc diffusion with penicillin 1 IU (P1, EUCAST) and penicillin 10 IU (P10, CLSI) was compared with nitrocefin discs (Cefinase®) and automated broth microdilution (Vitek2®). Oxacillin susceptibility was extrapolated from cefoxitin 30μg disc diffusion (FOX) and compared with Vitek2®. Reference methods were blaZ and mecA PCR. Penicillin zone diameter and zone edge correlated with blaZ in all except two P10 susceptible isolates (VME; very major error) and one P1 resistant isolate (ME). One hundred and forty-eight isolates were blaZ-negative of which one hundred and forty-six and one hundred and forty-nine isolates were susceptible by P1 and P10 respectively. One hundred and twenty-seven isolates were penicillin susceptible by Vitek2®. Vitek2® overcalled resistance in twenty-one blaZ-negative, twenty P1 and twenty-two P10 susceptible isolates (Vitek2® ME rate, 14.2%). Two mecA-positive isolates were oxacillin resistant by FOX and Vitek2® (categorical agreement). However, eighteen FOX susceptible, mecA-negative isolates tested resistant by Vitek2®. In conclusion, Vitek2® over-estimated penicillin and oxacillin resistance compared with disc diffusion and PCR. Disc diffusion with zone edge interpretation was more accurate and specific than automated broth microdilution for S. lugdunensis in our study.

Evaluation of penicillin G susceptibility testing methods for Staphylococcus lugdunensis

Background

Staphylococcus lugdunensis belongs to the CoNS group, but is regarded to be more virulent than most other CoNS. It is also remarkably susceptible to antibiotics, including penicillin G.

Objectives

To evaluate different methods for penicillin susceptibility testing, to assess penicillin susceptibility rates among S. lugdunensis and to describe the clinical presentation including antibiotic treatment.

Methods

Clinical isolates of S. lugdunensis were tested for penicillin susceptibility using disc diffusion according to CLSI (10 U disc) and EUCAST (1 U disc), assessment of zone-edge appearance, nitrocefin test and Etest for MIC determination. PCR of the blaZ gene was used as a reference method.

Results

Of the 112 isolates included in the study, 67% were susceptible to penicillin G according to blaZ PCR. The EUCAST disc diffusion test had 100% sensitivity, whereas the CLSI method had one very major error with a false-susceptible isolate. When zone-edge appearance was included in the assessment, the false-susceptible isolate was correctly classified as resistant. Foreign-body infection was the most common focus of infection, affecting 49% of the participants. Only 4% of the patients were treated with penicillin G.

Conclusions

Penicillin susceptibility is common in S. lugdunensis and the disc diffusion method according to EUCAST had a higher sensitivity than that of CLSI. Assessment of zone-edge appearance could increase the sensitivity of the disc diffusion test. Penicillin susceptibility testing and treatment should be considered in S. lugdunensis infections.

Update on Coagulase-Negative Staphylococci-What the Clinician Should Know

Coagulase-negative staphylococci (CoNS) are among the most frequently recovered bacteria in routine clinical care. Their incidence has steadily increased over the past decades in parallel to the advancement in medicine, especially in regard to the utilization of foreign body devices. Many new species have been described within the past years, while clinical information to most of those species is still sparse. In addition, interspecies differences that render some species more virulent than others have to be taken into account. The distinct populations in which CoNS infections play a prominent role are preterm neonates, patients with implanted medical devices, immunodeficient patients, and those with other relevant comorbidities. Due to the property of CoNS to colonize the human skin, contamination of blood cultures or other samples occurs frequently. Hence, the main diagnostic hurdle is to correctly identify the cases in which CoNS are causative agents rather than contaminants. However, neither phenotypic nor genetic tools have been able to provide a satisfying solution to this problem. Another dilemma of CoNS in clinical practice pertains to their extensive antimicrobial resistance profile, especially in healthcare settings. Therefore, true infections caused by CoNS most often necessitate the use of second-line antimicrobial drugs.

Equivalent effect of extracellular proteins and polysaccharides on biofilm formation by clinical isolates of Staphylococcus lugdunensis

Biofilm formation by Staphylococcus lugdunensis involves formation of an extracellular matrix; however, the identity of the constituents responsible for the structure of biofilms fabricated by different clinical strains is largely unclear. Here, biofilms produced by 24 clinical isolates of S. lugdunensis were characterized. The optimal medium for S. lugdunensis was selected, and the biofilm-forming capacity was assessed. Extracelullar polymeric substances (EPS) contributing to biofilm robustness were determined by evaluating the susceptibility of biofilms to EPS-degrading agents using field emission scanning electron microscopy and confocal laser scanning microscopy. Biofilm formation by the clinical isolates of S. lugdunensis was augmented by glucose supplementation. Further, extracellular DNA (eDNA), proteins, and polysaccharides were present in the 24 clinical isolates. Proteins and polysaccharides were the most common components within the S. lugdunensis biofilms, whereas the eDNA content was marginal in biofilm formation. Therefore, proteins and polysaccharides within biofilms may be used as the primary targets for developing eradication strategies to prevent S. lugdunensis biofilm formation.

Virulence Factors in Coagulase-Negative Staphylococci

Coagulase-negative staphylococci (CoNS) have emerged as major pathogens in healthcare-associated facilities, being S. epidermidis, S. haemolyticus and, more recently, S. lugdunensis, the most clinically relevant species. Despite being less virulent than the well-studied pathogen S. aureus, the number of CoNS strains sequenced is constantly increasing and, with that, the number of virulence factors identified in those strains. In this regard, biofilm formation is considered the most important. Besides virulence factors, the presence of several antibiotic-resistance genes identified in CoNS is worrisome and makes treatment very challenging. In this review, we analyzed the different aspects involved in CoNS virulence and their impact on health and food.

Endocarditis due to Staphylococcus lugdunensis-a retrospective national registry-based study

We present characteristics of infective endocarditis (IE) caused by Staphylococcus lugdunensis and compare with IE caused by Staphylococcus aureus and other CoNS, in the National Swedish Registry of IE (2008–2018). Thirty episodes of S. lugdunensis IE were registered, of which 21 cases affected native valves, and 7 patients were subjected to surgery. The mortality rate at 30 days was significantly higher for S. lugdunensis IE (20%, n = 6), than for IE caused by other CoNS (7%) or S. aureus (9%) p = 0.016. Septic embolisation was only reported in two cases (7%). The most common treatment was isoxazolyl penicillin (n = 18).

Cross-sectional study of Staphyloccus lugdunensis prevalence in cats

Staphylococcus lugdunensis is a commensal bacterium in humans and other animals that can cause serious infections. The aim of this research was to estimate the frequency of S. lugdunensis in pet cats and to characterize the S. lugdunensis isolates obtained. The prevalence of S. lugdunensis was 0.77% (4/523) in healthy cats and 1.23% (1/81) in sick cats. The isolates (N = 5), which colonized conjunctival sacs, nares, and the anus, were almost fully phenotypically sensitive to antibiotics, but harbored resistance genes to four chemotherapeutic groups. Their sequence types (STs) included ST2, ST3, ST9, and ST15. There was detected a far lower prevalence of S. lugdunensis in pet cats than is reported in the human population. Nevertheless, the phenotypic and genotypic properties of S. lugdunensis isolates found in the current study were very similar to those described previously in isolates of human origin.

Staphylococcus lugdunensis: Review of Epidemiology, Complications, and Treatment

Staphylococcus lugdunensis is a species of coagulase-negative staphylococci (CNS) that induces a variety of infectious diseases, including skin and soft tissue infection (SSTI), infective endocarditis (IE), and bone and PJI. This review article underscores the important points in the literature about S. lugdunensis infections, including its epidemiology, diagnosis, and treatment, as well as specific types of infections it can cause. Anatomical and age-related distributions of S. lugdunensis SSTIs have been noted, though they most commonly occur as abscesses. S. lugdunensis can also manifest as an aggressive form of IE presenting with valve destruction and abscess formation, frequently requiring surgery and with a high mortality rate. Bone and joint infections caused by S. lugdunensis are also more invasive than infections by other species of CNS. The clinical presentation of S. lugdunensis infection in SSTI, IE, and bone/joint infection is frequently more similar to that of S. aureus infection than that of other CNS infections, necessitating species-level differentiation of CNS for proper diagnosis. Though historically, this depended upon biochemical tests that were neither routine nor reliable, the implementation of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) in clinical laboratories has made identification of CNS species such as S. lugdunensis more practical. Imaging modalities, especially the fluorodeoxyglucose (FDG) with positron emission tomography (PET), are another important emerging trend in the diagnosis of infectious diseases such as S. lugdunensis infection. S. lugdunensis remains highly susceptible to a wide gamut of antibacterial therapies, which is uncharacteristic of other CNS. Infections can usually be treated by antibiotics traditionally used for CNS such as oxacillin. The breakpoints for S. lugdunensis are higher than those of other CNS and similar to S. aureus breakpoints. In the case of aggressive IE or bone/joint infection by S. lugdunensis, it is recommended to treat with a β-lactam agent. Further study is needed to understand the diversity, virulence, and population structure of this species, as well as its role in other infections, such as urinary tract infections (UTIs), respiratory infections, peritonitis, and bacteremia. 

Aggressive Staphylococcus lugdunensis Endocarditis in a Young Healthy Patient: A Case Report

Staphylococcus lugdunensis (S. lugdunensis) is a β-hemolytic coagulase-negative staphylococcus causing skin and soft tissue infections with an increasing incidence. Commonly found as normal flora in the perineal region, S. lugdunensis has been found in rare cases of infective endocarditis causing increased morbidity and mortality. We present a case of a previously healthy young male diagnosed with S. lugdunensis-caused infective endocarditis. A 31-year-old male with no significant past medical history, who presented to the emergency department with acute onset crushing substernal chest pressure and dyspnea with profuse sweating following 1-week-long febrile illness and malaise. The initial electrocardiogram (ECG) showed diffuse ST depressions in all precordial leads, consistent with an acute coronary syndrome. Emergent transthoracic echocardiogram revealed an ejection fraction (EF) of 45% with severe aortic insufficiency with emanating from a torn right coronary cusp. The patient had a cardiac arrest, and recovery of spontaneous circulation (ROSC) was obtained after 13 min. He subsequently underwent mechanical aortic valve replacement surgery. The native valve specimen cultures grew S. lugdunensis. Postoperatively and after a long course of antibiotics, the patient fully recovered without complications. S. lugdunensis is a common organism with increasing incidence that can lead to significant morbidity and mortality if not properly detected and treated. We hope this case presentation would support emergency valve replacement surgery in patients with S. lugdunensis-suspected infective endocarditis.

Clinical Performance of the Novel GenMark Dx ePlex Blood Culture ID Gram-Positive Panel

Rapid identification from positive blood cultures is standard of care (SOC) in many clinical microbiology laboratories. The GenMark Dx ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a multiplex nucleic acid amplification assay based on competitive DNA hybridization and electrochemical detection using eSensor technology. This multicenter study compared the investigational-use-only (IUO) BCID-GP Panel to other methods of identification of 20 Gram-positive bacteria, four antimicrobial resistance genes, and both Pan Candida and Pan Gram-Negative targets that are unique to the BCID-GP Panel.

Rapid identification from positive blood cultures is standard of care (SOC) in many clinical microbiology laboratories. The GenMark Dx ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a multiplex nucleic acid amplification assay based on competitive DNA hybridization and electrochemical detection using eSensor technology. This multicenter study compared the investigational-use-only (IUO) BCID-GP Panel to other methods of identification of 20 Gram-positive bacteria, four antimicrobial resistance genes, and both Pan Candida and Pan Gram-Negative targets that are unique to the BCID-GP Panel. Ten microbiology laboratories throughout the United States collected residual, deidentified positive blood culture samples for analysis. Five laboratories tested both clinical and contrived samples with the BCID-GP Panel. Comparator identification methods included each laboratory’s SOC, which included matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and automated identification systems as well as targeted PCR/analytically validated real-time PCR (qPCR) with bidirectional sequencing. A total of 2,342 evaluable samples (1,777 clinical and 565 contrived) were tested with the BCID-GP Panel. The overall sample accuracy for on-panel organisms was 89% before resolution of discordant results. For pathogenic Gram-positive targets (Bacillus cereus group, Enterococcus spp., Enterococcus faecalis, Enterococcus faecium, Staphylococcus spp., Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Listeria spp., Listeria monocytogenes, Streptococcus spp., Streptococcus agalactiae, Streptococcus anginosus group, Streptococcus pneumoniae, and Streptococcus pyogenes), positive percent agreement (PPA) and negative percent agreement (NPA) ranged from 93.1% to 100% and 98.8% to 100%, respectively. For contamination rule-out targets (Bacillus subtilis group, Corynebacterium, Cutibacterium acnes, Lactobacillus, and Micrococcus), PPA and NPA ranged from 84.5% to 100% and 99.9% to 100%, respectively. Positive percent agreement and NPA for the Pan Candida and Pan Gram-Negative targets were 92.4% and 95.7% for the former and 99.9% and 99.6% for the latter. The PPAs for resistance markers were as follows: mecA, 97.2%; mecC, 100%; vanA, 96.8%; and vanB, 100%. Negative percent agreement ranged from 96.6% to 100%. In conclusion, the ePlex BCID-GP Panel compares favorably to SOC and targeted molecular methods for the identification of 20 Gram-positive pathogens and four antimicrobial resistance genes in positive blood culture bottles. This panel detects a broad range of pathogens and mixed infections with yeast and Gram-negative organisms from the same positive blood culture bottle.

Tailoring Antimicrobial Susceptibility Testing to Individual Species of Coagulase-Negative Staphylococci: Next Up, Staphylococcus epidermidis

Accurate detection of methicillin resistance among staphylococci is vital for patient care. Methicillin resistance is most commonly mediated by acquisition of the mecA gene, which encodes an altered penicillin binding protein, PBP2a. Application of phenotypic methods to detect mecA-mediated beta-lactam resistance in staphylococci is becoming more complex as species-specific differences are identified among coagulase-negative staphylococci (CoNS). Previously, interpretative criteria and antimicrobial susceptibility testing (AST) methods specific to the CoNS group were used to evaluate Staphylococcus epidermidis A manuscript by S. N. Naccache, K. Callan, C.-A. D. Burnham, M. A. Wallace, et al. (J Clin Microbiol 57:e00961-19, 2019, https://doi.org/10.1128/JCM.00961-19) details experiments revealing that S. epidermidis, the most common clinically isolated CoNS, requires tailored use of previously described methods and interpretive criteria to reliably identify the presence of mecA-mediated methicillin resistance.