Significance of Staphylococcus lugdunensis bacteremia: report of 28 cases and review of the literature

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.

Central venous catheter-related bloodstream infections: Epidemiology and risk factors for hematogenous complications

BACKGROUND

Central catheter-related bloodstream infections (CRBIs) can lead to severe complications, including suppurative thrombophlebitis, endocarditis, and metastatic infections. While complications due to CRBIs caused by Staphylococcus aureus (SA) are well-known, there are limited data regarding CRBIs caused by other bacteria.

METHODS

This 2-year retrospective single-center study of patients with CRBIs from a tertiary care hospital examined the hematogenous complications associated with CRBIs according to patient characteristics, central venous catheter (CVC) types, and causative bacteria.

RESULTS

All in all, 254 patients with confirmed CRBIs were included; 285 bacteria types were isolated, mainly Enterobacteriaceae (n = 94), coagulase-negative Staphylococci (CNS, n = 82), SA (n = 45), and non-fermenting Gram-negative bacteria (NGB, n = 45). Among the patients, 35 developed at least one hematogenous complication (14 %), including suppurative thrombophlebitis (n = 15), endocarditis (n = 7) and metastatic infections (n = 16). In multivariate analysis, hemodialysis, persistent bacteremia for at least 3 days, and CRBIs caused by SA were associated with increased risk for hematogenous complications, while previous curative anticoagulant treatment was associated with reduced risk. Diabetes, CVC maintenance, and hematogenous complications were associated with increased 3-month mortality.

CONCLUSION

A thorough investigation of hematogenous complications should be envisioned in patients with persistent bacteremia, particularly those with SA infections and those on hemodialysis.

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.

Clinical and microbiological characteristics of Staphylococcus lugdunensis

PURPOSE OF REVIEW

This review provides an update on recent findings about the clinical and microbiological characteristics of Staphylococcus lugdunensis .

RECENT FINDINGS

European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) differ in their methodology and breakpoints for the detection of penicillin and oxacillin resistance in S. lugdunensis . The EUCAST method for beta-lactamase detection recommends a 1-unit penicillin disk and has demonstrated superior performance compared to the 10-unit penicillin disk recommended by CLSI. A similar outcome has been previously reported in Staphylococcus aureus. In addition, there is emerging oxacillin resistance in some geographical areas. Of particular concern is that oxacillin resistance in mecA positive isolates may not be reliably detected by current cefoxitin breakpoints.

SUMMARY

Coagulase negative staphylococci are now recognised as a heterogenous group of organisms that do not microbiologically or clinically behave the same way. The spectrum of clinical disease is species dependent and is particularly true for S. lugdunensis , which causes an array of clinical infections like that of S. aureus. Further studies are needed to assess the performance of phenotypic tests to detect resistance, to ensure that appropriate antimicrobial therapy is delivered to patients.

Identification of New Drug Target in Staphylococcus lugdunensis by Subtractive Genomics Analysis and Their Inhibitors through Molecular Docking and Molecular Dynamic Simulation Studies

Staphylococcus lugdunensis is a coagulase-negative, Gram-positive, and human pathogenic bacteria. S. lugdunensis is the causative agent of diseases, such as native and prosthetic valve endocarditis, meningitis, septic arthritis, skin abscesses, brain abscess, breast abscesses, spondylodiscitis, post-surgical wound infections, bacteremia, and peritonitis. S. lugdunensis displays resistance to beta-lactam antibiotics due to the production of beta-lactamases. This study aimed to identify potential novel essential, human non-homologous, and non-gut flora drug targets in the S. lugdunensis strain N920143, and to evaluate the potential inhibitors of drug targets. The method was concerned with a homology search between the host and the pathogen proteome. Various tools, including the DEG (database of essential genes) for the essentiality of proteins, the KEGG for pathways analysis, CELLO V.2.5 for cellular localization prediction, and the drug bank database for predicting the druggability potential of proteins, were used. Furthermore, a similarity search with gut flora proteins was performed. A DNA-binding response-regulator protein was identified as a novel drug target against the N920143 strain of S. lugdunensis. The three-dimensional structure of the drug target was modelled and validated with the help of online tools. Furthermore, ten thousand drug-like compounds were retrieved from the ZINC15 database. The molecular docking approach for the DNA-binding response-regulator protein identified ZINC000020192004 and ZINC000020530348 as the most favorable compounds to interact with the active site residues of the drug target. These two compounds were subjected to an MD simulation study. Our analysis revealed that the identified compounds revealed more stable behavior when bound to the drug target DNA-binding response-regulator protein than the apostate.

Staphylococcus lugdunensis endocarditis: lower mortality in the contemporary era?

Background

Staphylococcus lugdunensis is a virulent coagulase-negative Staphylococcus that is a rare cause of infective endocarditis (IE) associated with high mortality. A linear growth of IE has occurred over the past several years in Saskatchewan, with overlapping epidemics of human immunodeficiency virus (HIV)/hepatitis C virus driven by injection drug use (IDU). We hypothesized that given the unique challenges faced by our population with IDU and inequitable healthcare access, our cases of S. lugdunensis IE might differ from those in the published literature.

Methods

We retrospectively reviewed the cases of S. lugdunensis endocarditis admitted at our tertiary care hospitals in Saskatoon over a 6-year period and analyzed their baseline characteristics, antimicrobial susceptibility data, management, and outcome data, where available, for each patient.

Results

Of the 24 blood cultures positive for S. lugdunensis, as identified by our laboratory, we verified 6 cases of definite IE, and 2 cases of probable IE, applying the modified Duke’s criteria. A total of 5 of 8 cases involved native valves, with only 1 infection of the bioprosthetic mitral valve, seen in patient with IDU. A total of 5 of 8 cases involved the left-sided valves, with 1 of 8 involving the tricuspid valve. Only 1 death was recorded.

Conclusions

The male predominance and primarily left-sided valve infection we noted in our review were similar to results in the published literature. We noted a lower rate of surgical intervention and mortality than previously observed, which merits further study. We did not find coinfection with HIV and/or hepatitis C virus as an epidemiologic risk factor, likely owing to the low rate of IDU in our study.

Infectious diseases specialist consultation in Staphylococcus lugdunensis bacteremia

Background

Commensal coagulase negative Staphylococcus lugdunensis may cause severe bacteremia (SLB) and complications. Treatment of SLB is not fully established and we wanted to evaluate if infectious diseases specialist consultation (IDSC) would improve management and prognosis.

Methods

Multicenter retrospective study of SLB patients followed for 1 year. Patients were stratified according to bedside (formal), telephone (informal) or lack of IDSC within 7 days of SLB diagnosis.

Results

Altogether, 104 SLB patients were identified: 24% received formal bedside and 52% informal telephone IDSC whereas 24% were managed without any IDSC. No differences in demographics, underlying conditions or severity of illness were observed between the groups. Patients with bedside IDSC, compared to telephone IDSC or lack of IDSC, had transthoracic echocardiography more often performed (odds ratio [OR] 4.00; 95% confidence interval [CI] 1.31–12.2; p = 0.012) and (OR 16.0; 95% CI, 4.00–63.9; P<0.001). Bedside IDSC was associated with more deep infections diagnosed compared to telephone IDSC (OR, 7.44; 95% CI, 2.58–21.4; p<0.001) or lack of IDSC (OR, 9.56; 95% CI, 2.43–37.7; p = 0.001). The overall mortality was 7%, 10% and 17% at 28 days, 90 days and 1 year, respectively. Considering all prognostic parameters, patients with IDSC, compared to lack of IDSC, had lower 90 days and 1 year mortality (OR, 0.11; 95% CI, 0.02–0.51; p = 0.005) and (OR, 0.22; 95% CI, 0.07–0.67; p = 0.007).

Conclusion

IDSC may improve management and outcome of Staphylococcus lugdunensis bacteremia.

The role of Staphylococcus lugdunensis as a pathogen in children: a multicentre retrospective study

Introduction: Staphylococcus lugdunensis (SL), a tube coagulase negative Staphylococcus, is known to be pathogenic in adults, causing mainly skin infections.Gap Statement: Previous studies assessing SL's role in paediatric populations are sparse and are mainly limited to case reports.Aim: Present the clinical characteristics consistent with SL infections and its putative role as a pathogen in the paediatric population.Methodology: A retrospective multicentre study was conducted in four paediatric medical centres in Israel. Patients with isolates of SL presenting between 2009-2019 were included.Results: SL was isolated from 40 patients. Average (±SD) age at presentation was 5.9 (±6.2) years, with 22 (55 %) being female. Skin, soft tissue and musculoskeletal infections were the most common (n=20, 50%) followed by ear infections (n=13, 32.5%). Five cases of urine isolates and two isolates from blood culture samples were also reported. Skin abscess was the most common infection among skin and soft tissue isolates, reported in 17 children (85%) with SL being the only pathogen in 15 (75%). Otitis media was the most common ear infection accounting for 12 (92%) of all cases with SL as the only isolate reported in 6 (46%). Five cases of SL isolates from urine specimens were reported, all of which with poor growth of bacteria and normal urinalysis. Two cases of SL growth in blood culture were found in children presenting with signs and symptoms consistent with invasive blood stream infection.Conclusions: In the paediatric population, studied infections caused by SL are increasingly observed. The results of this study highlight its role as a pathogen in soft tissue infections and its putative role in otitis media and invasive blood stream infections. However, the role of SL as an uropathogen was not established.

Does This Patient Need Blood Cultures? A Scoping Review of Indications for Blood Cultures in Adult Nonneutropenic Inpatients

Guidance regarding indications for initial or follow-up blood cultures is limited. We conducted a scoping review of articles published between January 2004 and June 2019 that reported the yield of blood cultures and/or their impact in the clinical management of fever and common infectious syndromes in nonneutropenic adult inpatients. A total of 2893 articles were screened; 50 were included. Based on the reported incidence of bacteremia, syndromes were categorized into low, moderate, and high pretest probability of bacteremia. Routine blood cultures are recommended in syndromes with a high likelihood of bacteremia (eg, endovascular infections) and those with moderate likelihood when cultures from the primary source of infection are unavailable or when prompt initiation of antibiotics is needed prior to obtaining primary source cultures. In syndromes where blood cultures are low-yield, blood cultures can be considered for patients at risk of adverse events if a bacteremia is missed (eg, patient with pacemaker and severe purulent cellulitis). If a patient has adequate source control and risk factors or concern for endovascular infection are not present, most streptococci or Enterobacterales bacteremias do not require routine follow-up blood cultures.

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).

Staphylococcus lugdunensis: a Skin Commensal with Invasive Pathogenic Potential

Staphylococcus lugdunensis is a species of coagulase-negative staphylococcus (CoNS) that causes serious infections in humans akin to those of S. aureus It was often misidentified as S. aureus, but this has been rectified by recent routine use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in diagnostic laboratories. It encodes a diverse array of virulence factors for adhesion, cytotoxicity, and innate immune evasion, but these are less diverse than those encoded by S. aureus It expresses an iron-regulated surface determinant (Isd) system combined with a novel energy-coupling factor (ECF) mechanism for extracting heme from hemoproteins. Small cytolytic S. lugdunensis synergistic hemolysins (SLUSH), peptides related to phenol-soluble modulins of S. aureus, act synergistically with β-toxin to lyse erythrocytes. S. lugdunensis expresses a novel peptide antibiotic, lugdunin, that can influence the nasal and skin microbiota. Endovascular infections are initiated by bacterial adherence to fibrinogen promoted by a homologue of Staphylococcus aureus clumping factor A and to von Willebrand factor on damaged endothelium by an uncharacterized mechanism. S. lugdunensis survives within mature phagolysosomes of macrophages without growing and is released only following apoptosis. This differs fundamentally from S. aureus, which actively grows and expresses bicomponent leukotoxins that cause membrane damage and could contribute to survival in the infected host. S. lugdunensis is being investigated as a probiotic to eradicate S. aureus from the nares of carriers. However, this is contraindicated by its innate virulence. Studies to obtain a deeper understanding of S. lugdunensis colonization, virulence, and microbiome interactions are therefore warranted.

Complete genome sequence of a methicillin-resistant Staphylococcus lugdunensis strain and characteristics of its staphylococcal cassette chromosome mec

Symptoms of Staphylococcus lugdunensis infection are often similar to those of Staphylococcus aureus infection, including skin and soft-tissue lesions, bacteremia and infective endocarditis. Despite the severity of these infections, S. lugdunensis is regarded as a less important pathogen than drug-resistant S. aureus. To investigate its ability to cause infectious diseases, a methicillin-resistant S. lugdunensis (MRSL) strain JICS135 was isolated from a patient with bacteremia and subjected to whole genome sequencing. Similar to most strains of methicillin-resistant S. aureus (MRSA), this MRSL strain possessed the staphylococcal cassette chromosome mec (SCCmec) located close to the origin of replication. However, the SCCmec in this MRSL strain, with three ccr complexes, was structurally unique and currently untypable. Moreover, the SCCmec of this MRSL strain was found to carry two genes encoding microbial surface components recognizing adhesive matrix molecules (MSCRAMM)-like proteins accompanied by glycosyl transferases, one of which may have been derived from S. aureus and the other from S. epidermidis, indicating that this MRSL evolved to carry virulence factors from other staphylococci. The emergence of this strain, the first MRSL strain whose genome has been sequenced completely, may be of public concern.

Candida albicans and Staphylococcus lugdunensis superinfection of liver cysts in a patient with autosomal dominant polycystic kidney disease under prednisolone treatment

We report a case of superinfection of liver cysts caused by Candida albicans and Staphylococcus lugdunensis in a patient with autosomal dominant polycystic kidney disease. A 69-year-old man with chief complaints of headache and blurred vision was admitted to the former institution for the evaluation of suspected temporal arteritis. He was prescribed oral prednisolone (55 mg/day) as a preemptive treatment; however, he became febrile and presented with bilateral flank pain during prednisolone tapering. Blood culture revealed fungemia as a result of Candida famata infection; thus, micafungin treatment was started. Thereafter, recrudescence of the C-reactive protein level ensued. Then a cyst infection as visualized on magnetic resonance imaging led to cyst aspiration sclerotherapy. Cyst aspirate culture revealed the presence of C. albicans in one of the cysts and S. lugdunensis in two of the cysts. The patient was clinically stabilized with an additional 3 weeks of antibiotic and antifungal drug administration.

Design, synthesis, and discovery of novel oxindoles bearing 3-heterocycles as species-specific and combinatorial agents in eradicating Staphylococcus species

A series of new functionalized 3-indolylindolin-2-ones, 3-(1-methylpyrrol-2-yl)indolin-2-ones, and 3-(thiophen-2-yl)indolin-2-ones were synthesized by using novel indium (III)-catalysed reaction of various 3-diazoindolin-2-ones with indoles, 1-methylpyrrole, or thiophene via one-pot procedure. The newly synthesized compounds were characterized and screened for their in vitro antibacterial activity against various Staphylococcus species, including methicillin-resistant Staphylococcus aureus. results revealed that five compounds KS15, KS16, KS17, KS19, and KS20 exhibited potent and specific antibacterial activity against Staphylococcus species albeit inactive against Gram-negative bacteria. Especially, compounds exhibited superior antibacterial potency against Staphylococcus epidermidis compared to the reference drug streptomycin. The most potential compound KS16 also increased the susceptibility of Staphylococcus aureus to ciprofloxacin, gentamicin, kanamycin, and streptomycin. Among them, KS16 was found to be a synergistic compound with gentamicin and kanamycin. Furthermore, the cellular level of autolysin protein was increased from the KS16-treated Staphylococcus aureus cells. Finally, in vitro CCK-8 assays showed that KS16 exhibited no cytotoxicity at the minimum inhibitory concentrations used for killing Staphylococcus species. From all our results, novel oxindole compounds directly have lethal action or boost existing antibiotic power with the reduction of doses and toxicity in the treatment of multidrug-resistant Staphylococcus species.

fbl-Typing of Staphylococcus lugdunensis: A Frontline Tool for Epidemiological Studies, but Not Predictive of Fibrinogen Binding Ability

Staphylococcus lugdunensis is increasingly recognized as a potent pathogen, responsible for severe infections with an outcome resembling that of Staphylococcus aureus. Here, we developed and evaluated a tool for S. lugdunensis typing, using DNA sequence analysis of the repeat-encoding region (R-domain) in the gene encoding the fibrinogen (Fg)-binding protein Fbl (fbl-typing). We typed 240 S. lugdunensis isolates from various clinical and geographical origins. The length of the R-domain ranged from 9 to 52 repeats. fbl-typing identified 54 unique 18-bp repeat sequences and 92 distinct fbl-types. The discriminatory power of fbl-typing was higher than that of multilocus sequence typing (MLST) and equivalent to that of tandem repeat sequence typing. fbl-types could assign isolates to MLST clonal complexes with excellent predictive power. The ability to promote adherence to immobilized human Fg was evaluated for 55 isolates chosen to reflect the genetic diversity of the fbl gene. We observed no direct correlation between Fg binding ability and fbl-types. However, the lowest percentage of Fg binding was observed for isolates carrying a 5'-end frameshift mutation of the fbl gene and for those harboring fewer than 43 repeats in the R-domain. qRT-PCR assays for some isolates revealed no correlation between fbl gene expression and Fg binding capacity. In conclusion, this study shows that fbl-typing is a useful tool in S. lugdunensis epidemiology, especially because it is an easy, cost-effective, rapid and portable method (http://fbl-typing.univ-rouen.fr/). The impact of fbl polymorphism on the structure of the protein, its expression on the cell surface and in virulence remains to be determined.

A case of Staphylococcus lugdunensis bacteremia complicated by reactive arthritis

Reactive arthritis has been described infrequently in association with staphylococcal infections, both those secondary to Staphylococcus aureus and coagulase-negative staphylococci. We present a case of a 51-year-old male undergoing chemotherapy for pancreatic cancer who presented with joint pain and fevers and was found to have Staphylococcus lugdunensis bacteremia. Transthoracic and transesophageal echocardiograms were negative for endocarditis. Arthrocentesis from one large joint revealed culture-negative inflammatory synovitis. This case illustrates that a possible systemic manifestation of Staphylococcus lugdunensis bacteremia, in addition to the more common endocarditis, can also include reactive arthritis.

A Case Series of Staphylococcus lugdunensis Infection in Cancer Patients at an Academic Cancer Institute in the United States

Background

Staphylococcus lugdunensis is a coagulase-negative staphylococcus (CoNS) that is a part of the normal human skin flora. Even though it belongs to CoNS family, it can cause severe and destructive infections in a similar fashion to Staphylococcus aureus. Skin and soft tissue infections (SSTI), bacteremia and endocarditis are amongst the most common clinical presentations. Diagnosis and clinical presentation of infections caused by S. lugdunensis in cancer patients is limited.

Materials and Methods

We performed a retrospective chart review of 24 patients who had cultures positive for S. lugdunensis. Out of 24 patients, 14 patients were diagnosed with a true infection and 10 other patients were considered to be colonized with this pathogen. We analyzed clinical manifestation, treatment and response to therapy.

Results

SSTI was the most common presentation in our study patients. All patients diagnosed with SSTI had a prior surgery or an invasive procedure at the affected site. Five urinary tract infections (UTIs), one catheter-associated bloodstream infection, and a deep pelvic abscess were other reported infections in our study. We observed that S. lugdunensis remains susceptible to a variety of antibiotics, with all isolates susceptible to vancomycin and linezolid and most remain susceptible to fluoroquinolone and trimethoprim/ sulfamethoxazole. All 14 patients received antibiotics and improved.

Conclusion

In our case series, SSTI was common and diagnosed in 50% of the patients with clinically significant isolates for S. lugdunensis. This is consistent with prior studies indicating that S. lugdunensis is a significant pathogen in SSTIs. UTI was the second most common infection type in our patient population.

Genomic Alterations of Staphylococcus aureus ATCC 25923 after Prolonged Passage in the Laboratory

Staphylococcus aureus reference strain ATCC 25923 has been maintained for more than a decade in our laboratory. Genomic study revealed that the resulting strain AFIPCBER_B_8.4 has lost a 37-kb genomic fragment of the ATCC 25923 parental strain.

Staphylococcus aureus reference strain ATCC 25923 has been maintained for more than a decade in our laboratory. Genomic study revealed that the resulting strain AFIPCBER_B_8.4 has lost a 37-kb genomic fragment of the ATCC 25923 parental strain. The missing fragment showed sequence similarity to genes of bacteriophage proteins.

Staphylococcus lugdunensis sepsis and endocarditis in a newborn following lotus birth

A term newborn, who underwent lotus birth, developed Staphylococcus lugdunensis sepsis and endocarditis on the 1st day of life. This case reports an uncommon pathogen known to cause destructive endocarditis in the adult and paediatric populations, causing endocarditis in a neonate. We speculate that lotus birth, an atypical birthing practice, may have contributed to the development of this infection.

Staphylococcus lugdunensis endocarditis in children

We report the case of a 2-year-old boy with severe Langerhans cell histiocytosis who had tricuspid endocarditis caused by Staphylococcus lugdunensis and required surgery despite appropriate antimicrobial therapy. Through this case and literature review of endocarditis caused by S. lugdunensis in children, we highlight pitfalls and mistakes to be avoided in the management of this rare but serious infection.

Clinical and Microbiological Aspects of β-Lactam Resistance in Staphylococcus lugdunensis

Antimicrobial susceptibility results from broth microdilution MIC testing of 993 Staphylococcus lugdunensis isolates recovered from patients at a tertiary care medical center from 2008 to 2015 were reviewed. Ninety-two oxacillin-susceptible isolates were selected to assess the accuracy of penicillin MIC testing, the penicillin disk diffusion test, and three β-lactamase tests, including the cefoxitin-induced nitrocefin test, penicillin cloverleaf assay, and penicillin disk zone edge test. The results of all phenotypic tests were compared to the results of blaZ PCR. The medical records of 62 patients from whom S. lugdunensis was isolated, including 31 penicillin-susceptible and 31 penicillin-resistant strains, were retrospectively reviewed to evaluate the clinical significance of S. lugdunensis isolation, the antimicrobial agents prescribed, if any, and the clinical outcome. MIC testing revealed that 517/993 (52.1%) isolates were susceptible to penicillin and 946/993 (95.3%) were susceptible to oxacillin. The induced nitrocefin test was 100% sensitive and specific for the detection of β-lactamase compared to the blaZ PCR results, whereas the penicillin disk zone edge and cloverleaf tests showed sensitivities of 100% but specificities of only 9.1% and 89.1%, respectively. The penicillin MIC test had 100% categorical agreement with blaZ PCR, while penicillin disk diffusion yielded one major error. Only 3/31 patients with penicillin-susceptible isolates were treated with a penicillin family antimicrobial. The majority of cases were treated with other β-lactams, trimethoprim-sulfamethoxazole, or vancomycin. These data indicate that nearly all isolates of S. lugdunensis are susceptible to narrow-spectrum antimicrobial agents. Clinical laboratories in areas with resistance levels similar to those described here can help promote the use of these agents versus vancomycin by effectively designing their antimicrobial susceptibility reports to convey this message.

Staphylococcus lugdunensis infections, filling in the gaps: a 3-year retrospective review from a comprehensive cancer center

OBJECTIVE

Staphylococcus lugdunensis is considered to be more aggressive than other coagulase-negative staphylococci (CoNS). There are gaps in knowledge regarding the importance of isolating S. lugdunensis from different sources and in different patient subsets. Our objective was to describe the spectrum, clinical manifestations, and outcomes of infections caused by S. lugdunensis in patients with cancer.

METHODS

A retrospective review of all cancer patients from whom S. lugdunensis was isolated in a pure culture from clinically significant sites.

RESULTS

Between 2011 and 2014, 2263 CoNS were isolated, of them 45 S. lugdunensis were isolated in a pure culture and were included in this analysis. Only three patients were neutropenic. Skin and skin structure infections (SSSIs) occurred most often (36 cases) followed by five blood stream infections, one of which had destructive endocarditis and four infections at other sites. Of the 36 SSSIs, 29 were related to surgical or invasive procedures, and six of these involved an implanted medical device. All isolates were susceptible to vancomycin, 98% to levofloxacin and 89% to oxacillin. All patients responded to the therapy.

CONCLUSIONS

Cancer patients including those with neutropenia do not appear to have an increased frequency of infections caused by S. lugdunensis. SSSIs are predominant and are often associated with surgical procedures and/or implanted medical devices. Blood stream infections caused by S. lugdunensis are uncommon but may have an increased rate of serious complications such as endocarditis. Nevertheless, these organisms are generally susceptible to multiple classes of antimicrobial agents, and the overall response to therapy is high.

The occurrence of infective endocarditis with Staphylococcus lugdunensis bacteremia: A retrospective cohort study and systematic review

BACKGROUND

Staphylococcus lugdunensis is a coagulase-negative staphylococcus with similar virulence characteristics as Staphylococcus aureus. Whether S. lugdunensis causes infective endocarditis (IE) in a similar proportion of cases as S. aureus (reported to be 12.6% in a definitive multicenter prospective study) is unclear.

METHODS

We conducted a retrospective cohort study of adult patients with at least one blood culture positive for S. lugdunensis at our institution from January 2006 to December 2014. We examined microbiology data, ascertained disease severity and determined the proportion of patients with definite or possible IE based on the 2000 Modified Duke Criteria. Because coagulase-negative staphylococci were routinely identified to the species level at our institution from 2012 onwards, we determined the proportion of patients with definite or possible IE before and after implementation of routine speciation. We also compared our results with reported proportions of IE among patients with S. lugdunensis bacteremia (SLB) in other institutions by conducting a systematic review of the scientific literature. Nonparametric bootstrapping methods were performed to determine 95% confidence intervals (CI) for proportions of IE in patients with SLB.

RESULTS

Seventy-four patients with SLB were identified, of whom 64% (47/74) had sepsis by SIRS criteria, and 18% (13/74) had severe illness by Pittsburgh bacteremia score (PBS). Kaplan-Meier survival analysis showed that one-year survival among patients with severe illness was worse than patients with non-severe illness (p = 0.02). Fifteen percent (11/74) of patients had definite or possible IE (95% CI 6.8-23.0%). The proportion of SLB patients with definite or possible IE was 15.8% (6/38, 95% CI 5.3-28.9%) prior to routine speciation and 13.9% (5/36, 95% CI 2.8-27.8%) after routine speciation (p = 0.71). Among patients with at least two positive blood cultures for S. lugdunensis, 25% (10/40, 95% CI 12.5-40.0%) had IE. Systematic review of the literature yielded eight relevant retrospective studies. Of studies that included patients with one or more positive blood cultures for S. lugdunensis, the proportion of IE ranged from 6.3% to 27.0%.

CONCLUSION

The proportion of definite or possible IE among patients with SLB is similar to the proportion of IE among patients with S. aureus bacteremia. The proportions of IE among patients with SLB at other institutions fall within the 95% CI yielded by bootstrapping. Our findings suggest that growth of S. lugdunensis in two separate blood cultures should prompt consideration of workup for IE.

Clinical Features, Outcomes, and Molecular Characteristics of Community- and Health Care-Associated Staphylococcus lugdunensis Infections

Staphylococcus lugdunensis is a major cause of aggressive endocarditis, but it is also responsible for a broad spectrum of infections. The differences in clinical and molecular characteristics between community-associated (CA) and health care-associated (HA) S. lugdunensis infections have remained unclear. We performed a retrospective study of S. lugdunensis infections between 2003 and 2014 to compare the clinical and molecular characteristics of CA and HA isolates. We collected 129 S. lugdunensis isolates in total: 81 (62.8%) HA isolates and 48 (37.2%) CA isolates. HA infections were more frequent than CA infections in children (16.0% versus 4.2%, respectively; P = 0.041) and the elderly (38.3% versus 14.6%, respectively; P = 0.004). The CA isolates were more likely to cause skin and soft tissue infections (85.4% versus 19.8%, respectively; P < 0.001). HA isolates were more frequently responsible for bacteremia of unknown origin (34.6% versus 4.2%, respectively; P < 0.001) and for catheter-related bacteremia (12.3% versus 0%, respectively; P = 0.011) than CA isolates. Fourteen-day mortality was higher for HA infections than for CA infections (11.1% versus 0%, respectively). A higher proportion of the HA isolates than of the CA isolates were resistant to penicillin (76.5% versus 52.1%, respectively; P = 0.004) and oxacillin (32.1% versus 2.1%, respectively; P < 0.001). Two major clonal complexes (CC1 and CC3) were identified. Sequence type 41 (ST41) was the most common sequence type identified (29.5%). The proportion of ST38 isolates was higher for HA than for CA infections (33.3% versus 12.5%, respectively; P = 0.009). These isolates were of staphylococcal cassette chromosome mec element (SCCmec)type IV, V, or Vt. HA and CA S. lugdunensis infections differ in terms of their clinical features, outcome, antibiotic susceptibilities, and molecular characteristics.

Frequency, clinical manifestations, and outcomes of Staphylococcus lugdunensis Bacteremia in children

BACKGROUND

Staphylococcus lugdunensis (S. lugdunensis) is known as a common cause of clinically significant infections in adults although the clinical importance of S. lugdunensis isolates from pediatric samples is less known. The aim of this study is to assess the incidence, characteristics, and outcomes of S. lugdunensis bacteremia (SLB) in children.

METHODS

From January 2009 to March 2014, all blood culture isolates were retrospectively screened for S. lugdunensis. We analyzed the isolates for antimicrobial susceptibility and patients who had developed SLB by reviewing the electronic medical records. Additionally, we identified mecA and blaZ for available isolates by polymerase chain reaction (PCR).

RESULTS

Of the 647 positive blood cultures during the period, 277 (42.8%) yielded coagulase negative Staphylococcus (CoNS), and 10 of 277 CoNS were S. lugdunensis (3.6% of all CoNS isolates). Of eight SLB episodes identified, seven (87.5%) were considered to have clinically significant bacteremia. All patients had underlying diseases, and all SLB were either healthcare-associated or hospital acquired. There was no infectious endocarditis (IE) development. All patients were treated with antibiotics and recovered without sequelae. We found that the isolates in our study showed higher antibiotic resistance to penicillin (8/8: 100%) and oxacillin (6/8: 75.0%) than previously reported. Among isolates available, we detected mecA in all four isolates resistant to oxacillin and blaZ in 5 of 6 isolates resistant to penicillin.

CONCLUSIONS

S. lugdunensis is a rare but an important cause of bacteremia in children.

Embolic Stroke Caused by Staphylococcus lugdunensis Endocarditis Complicating Vasectomy in a 36-Year-Old Man

Staphylococcus lugdunensis is part of the native flora in the inguinal region of the body. Inguinal surgeries, such as vasectomy, place carriers of this aggressive pathogen at risk for contamination. Native-valve endocarditis caused by coagulase-negative S. lugdunensis has a rapid and complicated clinical course. The pathogenicity of this organism is not limited to cardiac valvular destruction. We report the case of a 36-year-old man who presented with S. lugdunensis endocarditis, dysarthria, and hemiparesis 5 weeks after a vasectomy. To our knowledge, this is the first report of embolic stroke caused by S. lugdunensis endocarditis. In addition, we discuss the relevant medical literature.

Important contribution of the novel locus comEB to extracellular DNA-dependent Staphylococcus lugdunensis biofilm formation

The coagulase-negative species Staphylococcus lugdunensis is an emerging cause of serious and potentially life-threatening infections, such as infective endocarditis. The pathogenesis of these infections is characterized by the ability of S. lugdunensis to form biofilms on either biotic or abiotic surfaces. To elucidate the genetic basis of biofilm formation in S. lugdunensis, we performed transposon (Tn917) mutagenesis. One mutant had a significantly reduced biofilm-forming capacity and carried a Tn917 insertion within the competence gene comEB. Site-directed mutagenesis and subsequent complementation with a functional copy of comEB verified the importance of comEB in biofilm formation. In several bacterial species, natural competence stimulates DNA release via lysis-dependent or -independent mechanisms. Extracellular DNA (eDNA) has been demonstrated to be an important structural component of many bacterial biofilms. Therefore, we quantified the eDNA in the biofilms and found diminished eDNA amounts in the comEB mutant biofilm. High-resolution images and three-dimensional data obtained via confocal laser scanning microscopy (CSLM) visualized the impact of the comEB mutation on biofilm integrity. The comEB mutant did not show reduced expression of autolysin genes, decreased autolytic activities, or increased cell viability, suggesting a cell lysis-independent mechanism of DNA release. Furthermore, reduced amounts of eDNA in the comEB mutant biofilms did not result from elevated levels or activity of the S. lugdunensis thermonuclease NucI. In conclusion, we defined here, for the first time, a role for the competence gene comEB in staphylococcal biofilm formation. Our findings indicate that comEB stimulates biofilm formation via a lysis-independent mechanism of DNA release.

Molecular Characteristics of Disease-Causing and Commensal Staphylococcus lugdunensis Isolates from 2003 to 2013 at a Tertiary Hospital in Taiwan

Objectives

Staphylococcus lugdunensis can cause community- and healthcare-associated infections. This study investigated the molecular characteristics of S. lugdunensis isolates collected at our hospital and compared the characteristics of the infectious and commensal isolates.

Methods

We collected the S. lugdunensis isolates between 2003 and 2013. The antimicrobial resistance test, SCCmec typing, accessory gene regulator (agr) typing, pulsed-field gel electrophoresis (PFGE), and δ-like hemolysin activity were performed.

Results

In total, 118 S. lugdunensis isolates were collected, of which 67 (56.8%) were classified into the infection group and 51 (43.2%) into the commensal group. The oxacillin resistance rate was 36.4%. The most common SCCmec types were SCCmec types V (51.4%) and II (32.6%). In total, 34 pulsotypes were identified. The PFGE typing revealed five clones (pulsotypes A, J, M, N, and P) at our hospital. Pulsotypes A and N caused the spread of high oxacillin resistance. In total, 10.2% (12 of 118) of the isolates lacked δ-like hemolysin activity. Compared with the infection group, the commensal group showed a higher percentage of multiple drug resistance and carried a higher percentage of SCCmec type II (11 of 22, 50% and 3 of 21, 14.3%) and a lower percentage of SCCmec type V (8 of 22, 36.4% and 14 of 21, 66.7%). The commensal group (27 PFGE types) showed higher genetic diversity than did the infection group (20 PFGE types). No difference was observed in the distribution of the five main pulsotypes, agr typing, and the presence of δ-like hemolysin activity between the two groups.

Conclusions

Five main clones were identified at our hospital. The commensal group showed higher genetic diversity, had a higher percentage of multidrug resistance, and carried a higher percentage of SCCmec type II and a lower percentage of SCCmec type V than did the infection group.

Persistence of a major endemic clone of oxacillin-resistant Staphylococcus lugdunensis sequence type 6 at a tertiary medical centre in northern Taiwan

OBJECTIVES

The aim of this study was to investigate the molecular epidemiology and clinical characteristics of a major clone of oxacillin-resistant Staphylococcus lugdunensis in a tertiary hospital.

METHODS

All S. lugdunensis isolated from sterile sites between June 2003 and May 2013 were collected for analysis. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed to study their genetic relationships.

RESULTS

A total of 118 S. lugdunensis isolates were analysed by PFGE. Three major PFGE pulsotypes were found: A, H, and L. Most of the pulsotype A isolates were oxacillin-resistant, and SCCmec type V and type VT. Isolates from another major clonal group that consisted primarily of pulsotype L were oxacillin-resistant and SCCmec type II. These 14 SCCmec type II S. lugdunensis isolates demonstrated high PFGE similarity and were obtained in the study hospital over a period of 40 months. Three of these 14 patients had clinically significant bacteraemia, and all three cases were in the intensive care unit. Further MLST analysis of the isolates identified an endemic S. lugdunensis strain of sequence type 6, clonal complex 1.

CONCLUSIONS

This study identified a major endemic clone of S. lugdunensis that is oxacillin-resistant, SCCmec type II, ST6, and capable of long-term persistence in the hospital. Continuous infection control surveillance and monitoring of S. lugdunensis should be considered in endemic areas.

Right-sided infective endocarditis with a ruptured sinus of Valsalva and multiple septic pulmonary emboli in a patient with atopic dermatitis

We herein report the case of 34-year-old woman with acute tricuspid valve infective endocarditis (IE) associated with a ruptured sinus of Valsalva and multiple septic pulmonary emboli. She had no history of medical problems, except for atopic dermatitis (AD). Blood cultures identified methicillin-sensitive Staphylococcus aureus. Despite the administration of two months of antibiotic therapy, the patient experienced recurrent pulmonary emboli and developed heart failure due to a left-to-right shunt, whereas the area of vegetation did not change in size. She subsequently underwent surgery for shunt closure and tricuspid valve replacement. The AD was thought to be the cause of the patient's bacteremia, which consequently resulted in aggressive right-sided IE.

Virulence factors among Staphylococcus lugdunensis are associated with infection sites and clonal spread

Staphylococcus lugdunensis has emerged as a significant human pathogen, with distinct clinical and microbiological characteristics. Our goal was to identify the virulence factors in S. lugdunensis recovered from infected patients of two Greek hospitals during a six-year period (2008-2013). A collection of 38 S. lugdunensis was tested for biofilm formation, antimicrobial susceptibility, clonal distribution, virulence factors (ica operon, fbl, atlL, vwbl, slush) and antibiotic resistance genes (mecA, ermC) carriage. Strains were classified into pulsotypes by pulsed-field gel electrophoresis (PFGE) of SmaI DNA digests. The majority (22) was isolated from skin and soft tissue infections (SSTIs), nine from deep-sited infections (DSIs), including three bacteraemias and seven from prosthetic device-associated infections (PDAIs). All isolates were oxacillin-susceptible, mecA-negative and fbl-positive. The highest resistance rate was detected for ampicillin (50%), followed by erythromycin and clindamycin (18.4%). Fourteen isolates (36.8%) produced biofilm, whereas 26/38 (68.4%) carried the ica operon. Biofilm formation was more frequent in isolates from PDAIs. Thirty-six strains (94.7%) carried atlL and 31 (81.6%) carried vwbl, whereas slush was detected in 15 (39.5%). PFGE revealed a low level of genetic diversity: strains were classified into seven pulsotypes, with two major clones (C: 22 and D: nine strains). Type C strains recovered from all infection sites prevailed in biofilm formation and ermC carriage, whereas type D strains associated with SSTIs and DSIs carried more frequently vwbl, slush or both genes. Despite susceptibility to antimicrobials, the clonal expansion and carriage of virulence factors, combined with biofilm-producing ability, render this species an important pathogen that should not be ignored.

The adhesive properties of the Staphylococcus lugdunensis multifunctional autolysin AtlL and its role in biofilm formation and internalization

Although it belongs to the group of coagulase-negative staphylococci, Staphylococcus lugdunensis has been known to cause aggressive courses of native and prosthetic valve infective endocarditis with high mortality similar to Staphylococcus aureus. In contrast to S. aureus, only little is known about the equipment of S. lugdunensis with virulence factors including adhesins and their role in mediating attachment to extracellular matrix and plasma proteins and host cells. In this study, we show that the multifunctional autolysin/adhesin AtlL of S. lugdunensis binds to the extracellular matrix and plasma proteins fibronectin, fibrinogen, and vitronectin as well as to human EA.hy926 endothelial cells. Furthermore, we demonstrate that AtlL also plays an important role in the internalization of S. lugdunensis by eukaryotic cells: The atlL-deficient mutant Mut17 adheres to and becomes internalized by eukaryotic cells to a lesser extent than the isogenic wild-type strain Sl253 and the complemented mutant Mut17 (pCUatlL) shows an increased internalization level in comparison to Mut17. Thus, surface localized AtlL that exhibits a broad binding spectrum also mediates the internalization of S. lugdunensis by eukaryotic cells. We therefore propose an internalization pathway for S. lugdunensis, in which AtlL plays a major role. Investigating the role of AtlL in biofilm formation of S. lugdunensis, Mut17 shows a significantly reduced ability for biofilm formation, which is restored in the complemented mutant. Thus, our data provide evidence for a significant role for AtlL in adherence and internalization processes as well as in biofilm formation of S. lugdunensis.

The short life of an aortic cusp aneurysm: a case report

This report describes a 42-year-old man with a history of lymphoma who is admitted with symptoms of chest pain, ST elevation changes, and elevated troponins. Immediate bedside echocardiographic evaluation led to an aborted urgent coronary angiography and a diagnosis of presumed endocarditis. Transesophageal echocardiography (TTE) subsequently revealed an aortic noncoronary cusp aneurysm masking as vegetation. The rapid assessment by TTE and transesophageal echocardiogram prevented an alternate course for this patient's management. We reviewed the necessity of heart catheterization in patients with significantly elevated troponins, pericarditis symptoms, and the rare sighting of aortic valve cusp aneurysms.

Coagulase-negative staphylococci

The definition of the heterogeneous group of coagulase-negative staphylococci (CoNS) is still based on diagnostic procedures that fulfill the clinical need to differentiate between Staphylococcus aureus and those staphylococci classified historically as being less or nonpathogenic. Due to patient- and procedure-related changes, CoNS now represent one of the major nosocomial pathogens, with S. epidermidis and S. haemolyticus being the most significant species. They account substantially for foreign body-related infections and infections in preterm newborns. While S. saprophyticus has been associated with acute urethritis, S. lugdunensis has a unique status, in some aspects resembling S. aureus in causing infectious endocarditis. In addition to CoNS found as food-associated saprophytes, many other CoNS species colonize the skin and mucous membranes of humans and animals and are less frequently involved in clinically manifested infections. This blurred gradation in terms of pathogenicity is reflected by species- and strain-specific virulence factors and the development of different host-defending strategies. Clearly, CoNS possess fewer virulence properties than S. aureus, with a respectively different disease spectrum. In this regard, host susceptibility is much more important. Therapeutically, CoNS are challenging due to the large proportion of methicillin-resistant strains and increasing numbers of isolates with less susceptibility to glycopeptides.

Multi-virulence-locus sequence typing of Staphylococcus lugdunensis generates results consistent with a clonal population structure and is reliable for epidemiological typing

Staphylococcus lugdunensis is an emergent virulent coagulase-negative staphylococcus responsible for severe infections similar to those caused by Staphylococcus aureus. To understand its potentially pathogenic capacity and have further detailed knowledge of the molecular traits of this organism, 93 isolates from various geographic origins were analyzed by multi-virulence-locus sequence typing (MVLST), targeting seven known or putative virulence-associated loci (atlLR2, atlLR3, hlb, isdJ, SLUG_09050, SLUG_16930, and vwbl). The polymorphisms of the putative virulence-associated loci were moderate and comparable to those of the housekeeping genes analyzed by multilocus sequence typing (MLST). However, the MVLST scheme generated 43 virulence types (VTs) compared to 20 sequence types (STs) based on MLST, indicating that MVLST was significantly more discriminating (Simpson's index [D], 0.943). No hypervirulent lineage or cluster specific to carriage strains was defined. The results of multilocus sequence analysis of known and putative virulence-associated loci are consistent with a clonal population structure for S. lugdunensis, suggesting a coevolution of these genes with housekeeping genes. Indeed, the nonsynonymous to synonymous evolutionary substitutions (dN/dS) ratio, the Tajima's D test, and Single-likelihood ancestor counting (SLAC) analysis suggest that all virulence-associated loci were under negative selection, even atlLR2 (AtlL protein) and SLUG_16930 (FbpA homologue), for which the dN/dS ratios were higher. In addition, this analysis of virulence-associated loci allowed us to propose a trilocus sequence typing scheme based on the intragenic regions of atlLR3, isdJ, and SLUG_16930, which is more discriminant than MLST for studying short-term epidemiology and further characterizing the lineages of the rare but highly pathogenic S. lugdunensis.

First record of isolation and characterization of methicillin resistant Staphylococcus lugdunensis from clinical samples in Iraq

This study was conducted to determine the frequency of Staphylococcus lugdunensis in different clinical samples. Out of 690 clinical samples, a total of 178 coagulase negative staphylococci (CoNS) isolates were recovered. CoNS were identified as 10 different species; 22 isolates belonged to Staphylococcus lugdunensis. Two specific genes for S. lugdunensis were used (tanA gene and fbl gene) to confirm identification. Both of these specific genes were detected in 15 (68.1%) of 22 isolates that were identified phenotypically. The results of oxacillin MIC showed that 7 of the 15 (46.6%) S. lugdunensis isolates were oxacillin resistant. The antibiotic susceptibility testing against 16 antibiotics showed that resistance rates were variable towards these antibiotics. Eight of fifteen S. lugdunensis isolates (53.3%) were β-lactamase producer. Results of molecular detection of mecA gene found that mecA gene was detected in 6 (40%) of 15 S. lugdunensis. All of these 6 isolates (S1, S2, S3, S4, S5, and S6) were resistant to oxacillin. One isolate (S7) was resistant to oxacillin but mecA was not detected in this isolate. This study is a first record of isolation and characterization of methicillin resistant S. lugdunensis (MRSL) from clinical samples in Iraq.

Staphylococcus colonization of the skin and antimicrobial peptides

Staphylococci are the most abundant skin-colonizing bacteria and the most important causes of nosocomial infections and community-associated skin infections. Molecular determinants of staphylococcal skin colonization include surface polymers and proteins that promote adhesion and aggregation, and a wide variety of mechanisms to evade acquired and innate host defenses. Antimicrobial peptides (AMPs) likely play a central role in providing immunity to bacterial colonization on human epithelia. Recent research has shown that staphylococci have a broad arsenal to combat AMP activity, and can regulate expression of AMP-resistance mechanisms depending on the presence of AMPs. While direct in vivo evidence is still lacking, this suggests that the interplay between AMPs and AMP resistance mechanisms during evolution had a crucial role in rendering staphylococci efficient colonizers of human skin.

Bacterial pathogens

Bacterial infections are frequent complications among patients treated for cancer. The type, severity, and treatment of bacterial infections vary and depend upon the specific malignancy, associated chemotherapies, and transplantation. This chapter discusses commonly encountered bacterial pathogens as well as Nocardia and mycobacteria in patients with cancer and addresses the clinical syndromes and management. Drug-resistant bacteria are becoming an increasingly recognized problem in patients with cancer. Antimicrobial resistance in select gram-positive and gram-negative bacteria are discussed along with the mechanisms of resistance and recommended therapies.

Staphylococcus lugdunensis Endocarditis Complicated by Embolism in an 18-Year-Old Woman with Mitral Valve Prolapse

Staphylococcus lugdunensis is a coagulase-negative staphylococcus (CNS). It is a major cause of prosthetic valve endocarditis; mitral valve prolapse (MVP) has emerged as a prominent predisposing structural cardiac abnormality. We describe a case of Staphylococcus lugdunensis endocarditis in an 18-year-old woman with preexisting mitral valve prolapse complaining of fever, a one-month history of continuous-remittent fever (T_max 38.6°C). The transthoracic echocardiogram revealed large vegetation on the anterior mitral valve leaflet flopping from the atrial side to the ventricular side. Five sets of blood cultures were positive for coagulase-negative staphylococci. During hospitalization, after two weeks of antibiotic therapy, the patient complained of sudden pain in her right leg associated with numbness. Lower limb arterial Doppler ultrasound showed an arterial thrombosis of right common iliac artery. Transfemoral iliac embolectomy was promptly performed and on septic embolus S. lugdunensis with the same antibiotic sensitivity and the same MIC values was again isolated. Our patient underwent cardiac surgery: triangular resection of the A2 with removal of infected tissue including vegetation. Our case is an example of infective endocarditis by S. lugdunensis on native mitral valve in a young woman of 18 with anamnesis valve prolapse.

[Venous catheter-related infections]

Central venous catheter-related infections can lead to a substantial increase in morbidity and mortality in patients. Nowadays, with the increase in multi-resistant bacteria, the recent appearance of new antibiotics, and the development of new treatment guidelines, means that this has to be constantly reviewed. The objective of this review is to briefly define the epidemiological and pathogenic concepts and to look in detail at the preventive and therapeutic measures of this type of infection. Practical aspects are presented of different clinical situations such as, antibiotic-lock of the central venous catheter, and the withdrawal or maintenance of the catheter.

Mortality and hospital stay related to coagulase-negative Staphylococci bacteremia in non-critical patients

OBJECTIVES

To describe the morbidity and mortality related to coagulase-negative Staphylococci (CNS) bacteremia in non-critical patients.

METHODS

Prospective, matched case-control study nested in a cohort. Patients with CNS bacteremia and no other isolate in blood cultures during their admission were defined as cases. Each case was matched by age, sex and area of hospitalization to one control. A 30-day follow-up was performed. Mortality and hospital stay were defined as endpoints.

RESULTS

105 cases and 105 controls were included. All cases carried intravascular catheters at the time of inclusion. Cases presented higher mortality compared to controls (14.3% vs. 4.8%), although this association was not independent in a multivariate analysis (p = 0.11). CNS bacteremia was independently associated with longer hospital stay (mean 12 vs. 8.5 days, p = 0.008). Moreover, when patients with CNS bacteremia were specifically analyzed, the persistence of fever (p = 0.005) and inappropriate empirical treatment (p = 0.04) were independently related to mortality.

CONCLUSION

We did not observe increased mortality attributable to CNS bacteremia, although it was associated with longer hospitalizations. Early appropriate empirical antibiotic therapy pending blood culture results might improve the outcome of patients with CNS bacteremia. Close follow-up is recommended if fever persists beyond 72 h.

Iron-regulated surface determinant (Isd) proteins of Staphylococcus lugdunensis

Staphylococcus lugdunensis is the only coagulase-negative Staphylococcus species with a locus encoding iron-regulated surface determinant (Isd) proteins. In Staphylococcus aureus, the Isd proteins capture heme from hemoglobin and transfer it across the wall to a membrane-bound transporter, which delivers it into the cytoplasm, where heme oxygenases release iron. The Isd proteins of S. lugdunensis are expressed under iron-restricted conditions. We propose that S. lugdunensis IsdB and IsdC proteins perform the same functions as those of S. aureus. S. lugdunensis IsdB is the only hemoglobin receptor within the isd locus. It specifically binds human hemoglobin with a dissociation constant (K(d)) of 23 nM and transfers heme on IsdC. IsdB expression promotes bacterial growth in an iron-limited medium containing human hemoglobin but not mouse hemoglobin. This correlates with weak binding of IsdB to mouse hemoglobin in vitro. Unlike IsdB and IsdC, the proteins IsdJ and IsdK are not sorted to the cell wall in S. lugdunensis. In contrast, IsdJ expressed in S. aureus and Lactococcus lactis is anchored to peptidoglycan, suggesting that S. lugdunensis sortases may differ in signal recognition or could be defective. IsdJ and IsdK are present in the culture supernatant, suggesting that they could acquire heme from the external milieu. The IsdA protein of S. aureus protects bacteria from bactericidal lipids due to its hydrophilic C-terminal domain. IsdJ has a similar region and protected S. aureus and L. lactis as efficiently as IsdA but, possibly due to its location, was less effective in its natural host.