Quality of life of patients treated for kidney stones 10-20mm in diameter in terms of the type of operation performed: A qualitative study

INTRODUCTION

Urolithiasis is a common chronic disease whose effect on patients' quality of life (QOL) is considerable but depends on the treatment received, differing between types of surgery. Intrarenal stones can be treated with different techniques: extracorporeal shock wave lithotripsy (ESWL), flexible ureteroscopy (fURS), and mini percutaneous nephrolithotomy (mini-PCNL), with proportional success and complication rates. The aim of this study was to qualitatively explore the impact of the different techniques on patients' QOL and understand their experiences of treatment choices.

METHODS

Patients treated for medium-sized kidney stones (10-20mm in diameter) were interviewed in a semi-structured manner. The interview data were transcribed and analyzed by theme according to consolidated criteria for reporting qualitative research (COREQ) guidelines.

RESULTS

Data saturation was achieved after interviewing 15 patients. The mean interview time was 34min (standard deviation (SD), 6.8min). The mean patient age was 54 years (SD, 9.5 years). Eight patients underwent ESWL, 10 were treated with fURS, and 8 underwent mini-PCNL. Twenty-seven subthemes were coded and regrouped into eight major themes, namely: no sense of choice in the decision-making process for eleven patients; extremely negative experiences of double-J stents for fourteen patients; concern about the risk of recurrence or treatment failure for thirteen patients; complicated hygiene and dietary recommendations for nine patients; technique-dependent postoperative outcomes; relatively well-tolerated operations for thirteen patients; a poor experience of sick leave, often because of a double-J stent; different views regarding future operations. In fact, a third of patients would choose the most effective treatment, a third would choose the simplest procedure and the last third would trust their urologist. Patients' experiences of these operations are variable.

CONCLUSION

Urologists must support their patients by presenting the different treatment options with clear, appropriate, and unbiased information. This should ensure patients take part in treatment decisions as part of a personalized treatment plan.

LEVEL OF EVIDENCE: 3

New host shift from human to cows within Staphylococcus aureus involved in bovine mastitis and nasal carriage of animal's caretakers

Staphylococcus aureus is a commensal and pathogen of both humans and bovines. While the epidemiology of both groups has been extensively studied individually, little is known about the potential zoonotic transfer from animal strains to human being and vice versa. To determine the S. aureus prevalence of bovine mastitis in Algeria and the zoonotic transfer of strains to human beings, mastitis milk samples were collected, and professionals in a close contact with bovines were nasal swabbed. S. aureus isolates were all characterized by methicillin resistance and spa-typing. DNA microarrays analysis was performed on a subset of strains in order to detect other virulence factors, including toxins, and to assign the isolates to theirs MLST clonal complexes. Overall, 116/222 (52.3%) cows suffered from mastitis, whose 38.8% (45/116) infected with S. aureus. Human nasal carriage was of 38% (49/129), with only 4 MRSA carriers (3.1%). A higher diversity of spa-types was observed in human (35/50) than in bovine (18/67) isolates, with a predominance of clonal complexes CC97 and CC22 in bovines. The typical animal clone CC97 was occasionally detected in human beings. Conversely, the CC22 S. aureus clone largely switched from humans to bovines. Our study highlights the potential dynamics of animal and human S. aureus strains in the farm environment in Algeria, which may represent a health threat in both populations.

Hidden Selection of Bacterial Resistance to Fluoroquinolones In Vivo: The Case of Legionella pneumophila and Humans

Background

Infectious diseases are the leading cause of human morbidity and mortality worldwide. One dramatic issue is the emergence of microbial resistance to antibiotics which is a major public health concern. Surprisingly however, such in vivo adaptive ability has not been reported yet for many intracellular human bacterial pathogens such as Legionella pneumophila.

Methods

We examined 82 unrelated patients with Legionnaire's disease from which 139 respiratory specimens were sampled during hospitalization and antibiotic therapy. We both developed a real time PCR assay and used deep-sequencing approaches to detect antibiotic resistance mutations in L. pneumophila and follow their selection and fate in these samples.

Findings

We identified the in vivo selection of fluoroquinolone resistance mutations in L. pneumophila in two infected patients treated with these antibiotics. By investigating the mutational dynamics in patients, we showed that antibiotic resistance occurred during hospitalization most likely after fluoroquinolone treatment.

Interpretation

In vivo selection of antibiotic resistances in L. pneumophila may be associated with treatment failures and poor prognosis. This hidden resistance must be carefully considered in the therapeutic management of legionellosis patients and in the control of the gradual loss of effectiveness of antibiotics.

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Legionellosis is a pneumonia caused by the inhalation of aerosols containing Legionella, mainly L. pneumophila.

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Its average mortality rate is 10%, despite availability of effective antibiotics such as the macrolides and the fluoroquinolones.

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Using modern molecular approaches, we identified the selection of fluoroquinolone resistance in L. pneumophila in patients under fluoroquinolone therapy.

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This may lead to reduction of treatment efficacy and prognosis worsening.

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Our findings should lead to revised guidelines for therapeutic management and prognosis evaluation of legionellosis.

α-Defensins partially protect human neutrophils against Panton-Valentine leukocidin produced by Staphylococcus aureus

α-Defensins produced by neutrophils are important effector molecules of the innate immune system. In addition to their microbicidal effects, α-defensins have the ability to neutralize bacterial toxins. Panton-Valentine leukocidin (PVL) is the hallmark of community-acquired methicillin-resistant Staphylococcus aureus. Staphylococcus aureus that produce PVL are responsible for severe diseases, including necrotizing pneumonia. Polymorphonuclear neutrophils (PMNs) are the target cells of PVL action. The goal of this study was to elucidate the effect of a group of α-defensins known as the human neutrophil peptides (HNPs) on the interactions between LukS-PV and LukF-PV, which compose PVL, and human PMNs. We observed that HNPs bound to both subunits of PVL and significantly decreased PVL pore formation in PMNs, with a maximum inhibition of 27%. When various HNP molecules were tested individually under the same conditions, we observed that HNP3, but not HNP1 or 2, decreased pore formation. Similarly, HNP3 significantly decreased PVL-induced PMN lysis, with a maximum inhibition of 31%. Interestingly, HNPs did not affect LukS-PV LukF-PV oligomerization, LukS-PV LukF-PV binding to PMNs or calcium influx induced by PVL in PMNs. Our results suggest that HNP3 partially protects neutrophils against PVL by interfering with the conformational changes of PVL required to form a functional pore.

SIGNIFICANCE AND IMPACT OF THE STUDY

Panton-Valentine leukocidin (PVL) is a pore-forming toxin produced by Staphylococcus aureus, responsible for neutrophil damage and key player of severe staphylococcal diseases. Antimicrobial peptides produced by neutrophils (HNP1-3) neutralize several other bacterial cytotoxins. We examined the impact of human neutrophil peptides (HNPs) on PVL cytotoxicity against human neutrophils and we found that HNPs bind to both LukS and LukF components of PVL, thereby inhibiting pore formation and neutrophil lysis. Our results suggest that HNP3 may impair PVL conformational changes required to form a functional pore and provide insight into the pathogenesis of PVL-related staphylococcal infection, with potential impact on the disease outcome.

Epidemiology of Staphylococcus aureus in Bangalore, India: emergence of the ST217 clone and high rate of resistance to erythromycin and ciprofloxacin in the community

This study aimed to determine the antibiotic susceptibility pattern of Staphylococcus aureus (SA) and the circulating clones in Bangalore, India. Susceptibility testing was performed for all cases of SA infections in a tertiary-care hospital. Panton-Valentine leucocidin (PVL) encoding genes were detected, and sequence type and spa type were determined. Out of the 92 collected strains, 52.2% were methicillin-resistant SA (MRSA), isolated from community-acquired (CA) infections in 60.4% and hospital-acquired (HA) infections in 39.6%. S. aureus isolates were also highly resistant to erythromycin (54.3%) and ciprofloxacin (70.6%) in methicillin-susceptible SA (MSSA) and MRSA, as well as in CA and HA infections. MRSA were found to be significantly more resistant to gentamicin (p <0.001), cotrimoxazole (p <0.001) and ciprofloxacin (p 0.001) than MSSA, but no significant difference was observed between CA- and HA-SA. ST217 appeared as a new emerging and prevalent clone, but ST772 remained the predominant clone, all being PVL-positive isolates. Our study points out the high prevalence of MRSA, even in the community, and the worrying increase of resistance to ciprofloxacin and erythromycin among CA-MSSA. Emergence of clone ST217 is reported for the first time in India.

Delta-toxin production deficiency in Staphylococcus aureus: a diagnostic marker of bone and joint infection chronicity linked with osteoblast invasion and biofilm formation

Biofilm formation, intra-osteoblastic persistence, small-colony variants (SCVs) and the dysregulation of agr, the major virulence regulon, are possibly involved in staphylococcal bone and joint infection (BJI) pathogenesis. We aimed to investigate the contributions of these mechanisms among a collection of 95 Staphylococcus aureus clinical isolates from 64 acute (67.4%) and 31 chronic (32.6%) first episodes of BJI. The included isolates were compared for internalization rate, cell damage and SCV intracellular emergence using an ex vivo model of human osteoblast infection. Biofilm formation was assessed in a microbead immobilization assay (BioFilm Ring test). Virulence gene profiles were assessed by DNA microarray. Seventeen different clonal complexes were identified among the screened collection. The staphylococcal internalization rate in osteoblasts was significantly higher for chronic than acute BJI isolates, regardless of the genetic background. Conversely, no differences regarding cytotoxicity, SCV emergence, biofilm formation and virulence gene distribution were observed. Additionally, agr dysfunction, detected by the lack of delta-toxin production using whole-cell matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) analysis (n = 15; 15.8%), was significantly associated with BJI chronicity, osteoblast invasion and biofilm formation. These findings provide new insights into MSSA BJI pathogenesis, suggesting the correlation between chronicity and staphylococcal osteoblast invasion. This adaptive mechanism, along with biofilm formation, is associated with agr dysfunction, which can be routinely assessed by delta-toxin detection using MALDI-TOF spectrum analysis, possibly providing clinicians with a diagnostic marker of BJI chronicity at the time of diagnosis.

The levels of antibodies to Panton-Valentine leukocidin (PVL) vary with PVL prevalence along a north-to-south gradient

Recent research on Staphylococcus aureus vaccine development has focused on active immunization against Panton-Valentine leukocidin (PVL), a potent leukotoxin associated with both superficial and severe deep-seated infections. PVL prevalence is highly variable worldwide, but it is unknown to what extent immunity to PVL varies between patients from geographic areas with different PVL-positive S. aureus prevalences. We conducted a retrospective multicentric study of anti-PVL and anti-alpha-toxin (Hla) antibody levels in uninfected adult patients from France (low PVL prevalence; n = 200), Algeria (moderate prevalence; n = 143), and Senegal (high prevalence; n = 228). The antibody levels were quantified by an enzyme-linked immunosorbent assay (ELISA) procedure. Because Hla is present in virtually all S. aureus strains, its corresponding antibody levels were considered to reflect population exposure to S. aureus. Compared with French participants, the average anti-PVL antibody levels were 2.5-fold and 8.2-fold higher in Algerian and Senegalese participants, respectively (p < 0.001). Conversely, anti-Hla antibody levels did not differ between participants from the three countries, suggesting that the observed differences in anti-PVL antibody levels were not biased by variations in population exposure to S. aureus. Hence, anti-PVL antibody levels in the general populations of France, Algeria, and Senegal vary widely and match variations in PVL-positive S. aureus strain prevalence, with an increasing north-to-south gradient. To conclude, immunity to PVL in a given population correlates with local PVL prevalence. This finding can help to inform PVL vaccine strategies.

Fatal NosocomialLegionella pneumophilaInfection Due to Exposure to Contaminated Water From a Washbasin in a Hematology Unit

A fatal nosocomial infection withLegionella pneumophilaserogroup 5 occurred in a patient with leukemia. Isolates recovered from both the potable water supply and the patient showed an identical genomic profile. With no other exposure identified, the water from the washbasin was evidently the source of infection.

Epidemiologic characteristics associated with ST23 clones compared to ST1 and ST47 clones of Legionnaires disease cases in France

In France, approximately 1200 cases of Legionnaires disease (LD) are reported annually, and isolates are available for approximately 20% of cases identified since 2000. All Legionella pneumophila serogroup 1 (sg1) isolates are characterized by sequence-based typing at the National Reference Centre. LD cases caused by L. pneumophila sg1 reported from 2008 through 2012 were considered for the study. Our study objective was to describe cases according to their sequence type (ST). We also constructed multivariable modified Poisson regression models to estimate the incidence rate ratio (IRR) and to identify characteristics potentially associated with ST23 clones compared to ST1 and ST47 clones. We studied 1192 patients infected by ST1 (n = 109), ST23 (n = 236), ST47 (n = 123) or other STs (n = 724). The geographic distribution of the ST23 cases across the country was significantly different compared to other ST groups. This genotype was significantly associated with the absence of corticosteroid therapy compared to ST1 (IRR = 0.56; p 0.016). Concerning exposure, the ST23 genotype was significantly less associated with hospital-acquired infections compared to ST1 (IRR = 0.32; p 0.001), but it was more associated with infections acquired in hospitals and elderly settings compared with ST47. Finally, the ST23 genotype was less frequently associated with travel than other STs. Despite the large number of cases of ST23 infection, we did not identify any characteristics specific to this ST. However, we identified independent associations between ST1 and nosocomial transmission and steroid therapy. These findings should encourage further exploration, especially in terms of environmental diffusion, strain virulence and host factors.

A new device for continuous assessment of gut perfusion: proof of concept on a porcine model of septic shock

INTRODUCTION

We evaluate an innovative device consisting of an enteral feeding tube equipped with a photoplethysmography (PPG) sensor in contact with the duodenal mucosa. This study aims to determine if the PPG signal, composed of a continuous (PDC) and a pulsatile part (PAC), is a reliable method to assess gut perfusion in a porcine model of septic shock.

METHOD

Fourteen piglets were anesthetized and mechanically ventilated. They were randomly assigned to two groups: the nonseptic (NS) group received an infusion of Ringer's lactate solution (RL) alone, the septic (S) group received in addition a suspension of live Pseudomonas aeruginosa. Heart rate (HR), pulse oximetry (SpO2), mean arterial pressure (MAP), cardiac index (CI) and serum lactates were recorded and gut microcirculation (GM) was monitored with a laser Doppler probe applied on the duodenal serosa. PDC and PAC were given by the PPG probe inserted in the duodenum. Data was collected every 15 minutes (t0, t15…) during 150 minutes (t150). After administration of the bacteria suspension (t0), resuscitation maneuvers were performed following a defined algorithm. GM PAC, and PDC were expressed as variation from baseline (GMvar, PACvar, PDCvar). Analysis of variance (ANOVA) with repeated measures was performed to compare hemodynamic variables, with Bonferroni correction as post hoc analysis on t0, t60 and t150.

RESULTS

One piglet was withdrawn from analysis due to a defective probe. S group (six piglets) received resuscitation therapy while NS group (seven piglets) did not. A significant group effect was found for the all parameters except HR. Post hoc analysis found a significant decrease for GM and PAC at t60. The correlation between PAC, PDC and microcirculatory parameters were as follows: rPACvar-GMvar = 0.496, P <0.001, rPDCvar-GMvar = 0.244; P = 0.002. In the septic group, correlations were as follows: rPAC-lactate = -0.772, P <0.001; rPDC-lactate = -0.681, P <0.01). At the onset of shock, a decrease of PAC, PDC and GM occurred before the alteration of MAP.

CONCLUSIONS

PAC and PDC decreased at the onset of shock and were correlated with GM and lactate. These results confirm that PPG signal reliably reflects the early perfusion alteration of the gut. Further studies should assess the clinical use of this device.

α-Hemolysin, not Panton-Valentine leukocidin, impacts rabbit mortality from severe sepsis with methicillin-resistant Staphylococcus aureus osteomyelitis

BACKGROUND

Severe sepsis, combining acute osteomyelitis and lung involvement, has been described increasingly in healthy children with the spread of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA).

METHODS

Outcomes (mortality, hematogenous spread, lung and bone involvements) of rabbit osteomyelitis caused by CA-MRSA LAC(WT) USA300 and its Panton-Valentine leukocidin (PVL)- and α-hemolysin (Hla)-negative isogenic derivatives (LACΔpvl and LACΔhla, respectively) were compared.

RESULTS

Three days after inoculation (D3), all LAC(WT)- and LACΔpvl-, and 72% of LACΔhla-infected rabbits had no hematogenous spread and similar lung and bone bacterial densities. LACΔpvl and LACΔhla caused less severe histological lung lesions than LAC(WT) (P ≤ .01). Between D3 and D9, 10 (53%) LAC(WT)-, 11 (55%) LACΔpvl-, but no LACΔhla-infected rabbits (P < .005) died of severe sepsis with disseminated infection. Unlike deceased animals, most LAC(WT), LACΔpvl, and LACΔhla D14 survivors had no hematogenous spread (P < .001). LAC(WT) (88%) caused more bone abscesses than LACΔpvl (0, P = .001) or LACΔhla (30%, P = .01).

CONCLUSION

In this model, both PVL and Hla seemed to be required for early lung involvement via hematogenous spread. Hla, but not PVL, significantly impacted severe sepsis-related mortality. PVL was the predominant factor determining late-stage bone abscesses.

Basic rules of hygiene protect health care and lab workers from nasal colonization by Staphylococcus aureus: an international cross-sectional study

Acquisition of nasal Staphylococcus aureus (S. aureus) colonization by contaminated hands is likely an important determinant of its nasal carriage rate in health care and lab setting. The objective of our cross-sectional study was to assess the prevalence of nasal methicillin-sensitive (MSSA) or -resistant Staphylococcus aureus (MRSA) carriage among health care professionals (HCPs) attending an international symposium and to study the association between compliance with hygiene rules, individual-related parameters, and medical conditions with nasal S. aureus carriage in this population. After obtaining consent, two nasal swabs were collected. Nasal MSSA and MRSA carriage was measured by the: i) molecular approach targeting spa, mecA and mecA-orfX junction sequences, and ii) culture on selective S. aureus media combined with mecA molecular detection of isolated strains. Information on compliance with hygiene rules, demographic variables, sector of activity and long-term medication was collected by anonymous questionnaire. The participation rate was 32.3%. In total, 176 subjects from 34 countries were included in the analysis. S. aureus was isolated from the nasal swabs of 57 (32.4%) subjects, of whom 3 (5.3%) harbored MRSA strains. Overall, 123 subjects reported working in microbiology laboratories with direct manipulation of S. aureus, and 29 acknowledged regular contacts with patients. In this exposed population, hydro-alcoholic solutions appeared to have a significant protective effect against nasal S. aureus carriage (OR = 0.36; 95% CI: 0.15-0.85). Hospital work was associated with increased risk of nasal S. aureus carriage (OR = 2.38; 95% CI: 1.07-5.29). The results of this study showed that compliance with basic rules of hygiene, such as the use of hydro-alcoholic solutions, could reduce the risk of nasal S. aureus colonization. Hydro-alcoholic solution could interrupt auto-transmission of the pathogen, consequently decreasing the overall nasal carriage rate, specifically in transient carriers.

Hospital washbasin water: risk of Legionella-contaminated aerosol inhalation

The contamination of aerosols by washbasin water colonized by Legionella in a hospital was evaluated. Aerosol samples were collected by two impingement technologies. Legionella was never detected by culture in all the (aerosol) samples. However, 45% (18/40) of aerosol samples were positive for Legionella spp. by polymerase chain reaction, with measurable concentrations in 10% of samples (4/40). Moreover, immunoassay detected Legionella pneumophila serogroup 1 and L. anisa, and potentially viable bacteria were seen on viability testing. These data suggest that colonized hospital washbasins could represent risks of exposure to Legionella aerosol inhalation, especially by immunocompromised patients.

Staphylococcal entertotoxins of the enterotoxin gene cluster (egcSEs) induce nitrous oxide- and cytokine dependent tumor cell apoptosis in a broad panel of human tumor cells

The egcSEs comprise five genetically linked staphylococcal enterotoxins, SEG, SEI, SElM, SElN, and SElO and two pseudotoxins which constitute an operon present in up to 80% of Staphylococcus aureus isolates. A preparation containing these proteins was recently used to treat advanced lung cancer with pleural effusion. We investigated the hypothesis that egcSEs induce nitrous oxide (NO) and associated cytokine production and that these agents may be involved in tumoricidal effects against a broad panel of clinically relevant human tumor cells. Preliminary studies showed that egcSEs and SEA activated T cells (range: 11-25%) in a concentration dependent manner. Peripheral blood mononuclear cells (PBMCs) stimulated with equimolar quantities of egcSEs expressed NO synthase and generated robust levels of nitrite (range: 200-250 μM), a breakdown product of NO; this reaction was inhibited by NG-monomethyl-L-arginine (L-NMMA) (0.3 mM), an NO synthase antagonist. Cell free supernatants (CSFs) of all egcSE-stimulated PBMCs were also equally effective in inducing concentration dependent tumor cell apoptosis in a broad panel of human tumor cells. The latter effect was due in part to the generation of NO and TNF-α since it was significantly abolished by L-NMMA, anti-TNF-α antibodies, respectively, and a combination thereof. A hierarchy of tumor cell sensitivity to these CFSs was as follows: lung carcinoma > osteogenic sarcoma > melanoma > breast carcinoma >neuroblastoma. Notably, SEG induced robust activation of NO/TNFα-dependent tumor cell apoptosis comparable to the other egcSEs and SEA despite TNF-α and IFN-γ levels that were 2 and 8 fold lower, respectively, than the other egcSEs and SEA. Thus, egcSEs produced by S. aureus induce NO synthase and the increased NO formation together with TNF-α appear to contribute to egcSE-mediated apoptosis against a broad panel of human tumor cells.

Severe leukopenia in Staphylococcus aureus-necrotizing, community-acquired pneumonia: risk factors and impact on survival

Background

Necrotizing pneumonia attributed to Panton-Valentine leukocidin-positive Staphylococcus aureus has mainly been reported in otherwise healthy children and young adults, with a high mortality rate. Erythroderma, airway bleeding, and leukopenia have been shown to be predictive of mortality. The objectives of this study were to define the characteristics of patients with severe leukopenia at 48-h hospitalization and to update our data regarding mortality predicting factors in a larger population than we had previously described.

Methods

It was designed as a case-case study nested in a cohort study. A total of 148 cases of community-acquired, necrotizing pneumonia were included. The following data were collected: basic demographic information, medical history, signs and symptoms, radiological findings and laboratory results during the first 48 h of hospitalization. The study population was divided into 2 groups: (1) with severe leukopenia (leukocyte count ≤3,000 leukocytes/mL, n=62) and (2) without severe leukopenia (>3,000 leukocytes/mL, n=86).

Results

Median age was 22 years, and the male-to-female gender ratio was 1.5. The overall in-hospital mortality rate was 41.2%. Death occurred in 75.8% of severe leukopenia cases with median survival time of 4 days, and in 16.3% of cases with leukocyte count >3,000/mL (P<0.001). Multivariate analysis indicated that the factors associated with severe leukopenia were influenza-like illness (adjusted odds ratio (aOR) 4.45, 95% CI (95% confidence interval) 1.67-11.88, P=0.003), airway bleeding (aOR 4.53, 95% CI 1.85-11.13, P=0.001) and age over 30 years (aOR 2.69, 95% CI 1.08-6.68, P=0.033). A personal history of furuncles appeared to be protective (OR 0.11, 95% CI 0.01-0.96, P=0.046).

Conclusion

S. aureus-necrotizing pneumonia is still an extremely severe disease in patients with severe leukopenia. Some factors could distinguish these patients, allowing better initial identification to initiate adapted, rapid administration of appropriate therapy.

PSMs of hypervirulent Staphylococcus aureus act as intracellular toxins that kill infected osteoblasts

Epidemic community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is associated with more severe and acute forms of osteomyelitis than healthcare-associated (HA-) MRSA. Although S. aureus is now recognized as a facultative intracellular pathogen, the contribution of osteoblast invasion by CA-MRSA to the pathogenesis of osteomyelitis is unknown. Using an ex vivo model of intracellular infection of human osteoblasts, we demonstrated that CA-MRSA strains of diverse lineages share an enhanced ability to kill infected osteoblasts compared to HA-MRSA. Cytotoxicity comparisons of CA-MRSA isogenic deletion mutants revealed that phenol-soluble modulins (PSMs), a class of membrane-damaging exoproteins that are expressed at higher levels in CA-MRSA than in HA-MRSA, are involved in this osteoblast killing, whereas other major CA-MRSA virulence determinants, the Panton-Valentine leukocidin and alpha-toxin, are not involved. Similarly, functional agr and sarA regulators, which control the expression of PSMs and alpha-toxin, were required for the expression of the intracellular cytotoxic phenotype by CA-MRSA, whereas the saeRS regulator, which controls the expression of alpha-toxin but not PSMs, had no impact on cytotoxicity. Finally, PSM transcript levels determined by quantitative reverse-transcriptase PCR were significantly higher in CA-MRSA than in HA-MRSA strains and associated with cell damage in MRSA-infected osteoblasts. These findings provide new insights into the pathogenesis of severe CA-MRSA osteomyelitis and unravel a novel virulence strategy of CA-MRSA, based on the invasion and subsequent killing of osteoblasts by PSMs acting as intracellular toxins.

Inflammasome activation restricts Legionella pneumophila replication in primary microglial cells through flagellin detection

Microglial cells constitute the first line of defense of the central nervous system (CNS) against microbial invasion. Pathogens are detected thanks to an array of innate immune receptors termed pattern recognition receptors (PRRs). PRRs have been thoroughly characterized in bone marrow-derived macrophages, but the PRRs repertoire and functionality in microglial cells remain largely unknown. Microglial cells express various Toll-like Receptors and the Nod1/2 receptors. Recently, a novel innate immune signalling pathway, the inflammasome pathway has been uncovered. Inflammasome activation leads to caspase-1 activation, release of the proinflammatory cytokines, IL-1β and IL-18 and cell death in a process termed pyroptosis. One inflammasome receptor, NLRP3, has been characterized in microglial cells and associated with response to infections and in the initiation of neuro-degeneration in an Alzheimer's disease model. Legionella pneumophila (L.pneumophila) is a flagellated bacterium replicating within macrophages. In bone marrow-derived macrophages, L. pneumophila is detected in a flagellin-dependent manner by the Naip5-NLRC4 (Ipaf) inflammasome pathway. In this study, we decided to use L. pneumophila to investigate the presence and the functionality of this inflammasome in primary murine microglial cells. We show that microglial cells detect L. pneumophila infection in a flagellin-dependent manner leading to caspase-1-mediated bacterial growth restriction, infected cell death and secretion of the proinflammatory cytokines IL-1β and IL18. Overall, our data demonstrate that microglial cells have a functional Naip5-NLRC4 inflammasome likely to be important to monitor and clear CNS infections by flagellated bacteria.

Methicillin resistance is not a predictor of severity in community-acquired Staphylococcus aureus necrotizing pneumonia--results of a prospective observational study

Staphylococcal necrotizing pneumonia (NP) is a severe disease associated with Panton-Valentine leucocidin (PVL). NP was initially described for methicillin-susceptible Staphylococcus aureus (MSSA) infection, but cases associated with methicillin-resistant S. aureus (MRSA) infection have increased concomitantly with the incidence of community-acquired MRSA worldwide. The role of methicillin resistance in the severity of NP remains controversial. The characteristics and outcomes of 133 patients with PVL-positive S. aureus community-acquired pneumonia (CAP) were compared according to methicillin resistance. Data from patients hospitalized for PVL-positive S. aureus CAP in France from 1986 to 2010 were reported to the National Reference Centre for Staphylococci and were included in the study. The primary end point was mortality. Multivariate logistic modelling and the Cox regression were used for subsequent analyses. We analysed 29 cases of PVL-MRSA and 104 cases of PVL-MSSA pneumonia. Airway haemorrhages were more frequently associated with PVL-MSSA pneumonia. However, no differences in the initial severity or the management were found between these two types of pneumonia. The rate of lethality was 39% regardless of methicillin resistance. By Cox regression analysis, methicillin resistance was not found to be a significant independent predictor of mortality at 7 or 30 days (p 0.65 and p 0.71, respectively). Our study demonstrates that methicillin resistance is not associated with the severity of staphylococcal necrotizing pneumonia.

ST93-Queensland community-acquired meticillin-resistant Staphylococcus aureus clone in France: outbreak in a scout camp and sporadic cases, July to August 2012

We describe the occurrence in France of a Panton-Valentine leukocidin (PVL)-positive meticillin-resistant Staphylococcus aureus (MRSA) ST93 clone, a predominant community-acquired (CA)-MRSA in Australia. In July to August 2012, an outbreak in a scout camp (n=3) and sporadic cases (n=2) of skin and soft tissue infections were reported. Investigations suggested importation of the clone through travel and onward transmission. This illustrates the epidemic potential of this lineage and the role of travellers in the spread of PVL-positive CA-MRSA.

Epidemiological data of staphylococcal scalded skin syndrome in France from 1997 to 2007 and microbiological characteristics of Staphylococcus aureus associated strains

Epidemiological data on staphylococcal scalded skin syndromes (SSSS), including bullous impetigo (BI) and generalized exfoliative syndrome (GES), are scarce. To better characterize SSSS and associated Staphylococcus aureus strains, we conducted a retrospective study of 349 cases collected in France between 1997 and 2007 by the National Reference Centre of Staphylococci. Our results showed a stationary evolution of SSSS cases, with a heterogeneous distribution of cases in France. Although notification was not exhaustive, we estimated an incidence of 0.56 cases/year/million inhabitants, in accordance with previous studies conducted in France and Europe, with a median age of 2 years old and sex ratios of 1. A seasonal effect was observed, with a higher GES/BI ratio in autumn compared with other seasons, which could be explained by the impact of viral co-infection. Genetic analysis of S. aureus strains showed that accessory gene regulator (agr) 4, exfoliative toxin A (eta) and B (etb) genes, staphylococcal and enterotoxin-like O (selo) gene and agr4 etb selo profiles were predominantly associated with GES, whereas agr2 eta and agr4 eta selo were more frequently observed with BI. Only one methicillin-resistant strain was found. Protein A (spa) typing identified two main genotypes: spa clonal complex (CC) 159/sequence-type (ST) 121 (75%) and spaCC346/ST15 (18%). spaCC159 was mainly associated with agr4 eta etb selo, agr4 eta selo and agr4 etb selo, and spaCC346 was mainly associated with agr2 eta, suggesting that French SSSS cases are caused by these two main lineages. However, in a multivariate analysis, only etb was independently associated with GES.

The effect of inactivated Lactobacillus LB fermented culture medium on symptom severity: observational investigation in 297 patients with diarrhea-predominant irritable bowel syndrome

INTRODUCTION

Little is known about the intensity of symptoms of diarrhea-predominant IBS (IBS-D) or the consequences of the disease on patients' health-related quality of life (HRQOL). This observational investigation assessed the symptoms (abdominal pain, bloating, number of stools per day, and stool consistency), impact on HRQOL, and consequence on anal continence in 297 patients with IBS-D before and after 1 month of probiotic treatment with Lacteol (inactivated Lactobacillus LB plus fermented culture medium).

METHODS

Functional assessment using a standardized visual analogue scale in order to quantify abdominal pain, bloating, and quality of life before and after 1 month of treatment with 2 capsules/day of Lacteol. The number of symptomatic days per week, number of stools, consistency of stools, secondary fecal incontinence rate, and potential trigger effect of food were quantified. A χ2 test was used to compare qualitative data and the variance of quantitative criteria was analyzed.

RESULTS

The pain score decreased from 4.46±0.15 on a scale of 0-10 before treatment to 2.8±0.14 after treatment (p<0.0001). Bloating decreased from 4.49±0.18 to 2.5±0.15 on a scale of 0-10 (p<0.0001). The HRQOL score, which is inversely correlated with quality of life, decreased from 5.99±0.14 to 3.92±0.16 (p<0.0001). In this cohort study, the fecal incontinence rate secondary to diarrhea was clearly higher than that of the general population: 18% versus a prevalence of 9-10%, according to different studies. The mean number of stools per week decreased from 17.59 to 12.83 after treatment (p<0.0001). Before treatment, 54% of patients had watery stools and 46% had smooth stools; at the end of treatment, only 18.5% of patients still had watery stools, and 34% had normal stools. 52% of patients attributed their symptoms to their diet: 34% to vegetables, 29% to fruit, 15% to milk, 15% to fat, 6% to peppers and spices, and 4% to sugar.

CONCLUSION

This observational investigation shed new light on patients with IBS-D, the HRQOL of which is altered by a fecal incontinence rate twice as high as that of the general population. Correlation with diet is confirmed by 1 out of 2 patients reporting poor tolerance of fiber and dairy products. Nutritional management should thus be part of these patients' treatment. Inactivated Lactobacillus LB plus fermented culture medium is a probiotic drug that has been used by physicians for a long time to treat patients with diarrhea. Strongly concentrated, it has no side effects and seems to help these patients. Due to a strong placebo effect in patients with this pathology, however, a controlled study is necessary to confirm this result.

Antibacterial resistance, genes encoding toxins and genetic background among Staphylococcus aureus isolated from community-acquired skin and soft tissue infections in France: a national prospective survey

The epidemiology of staphylococcal community-acquired skin and soft tissues infections (CA-SSTIs) has changed dramatically. We described prospectively the characteristics of the Staphylococcus aureus isolated from 71 non-teaching French hospitals and implicated in CA-SSTIs: antimicrobial susceptibility (mecA polymerase chain reaction [PCR], disk diffusion method), virulence factor gene (sea, tst, pvl) prevalence and genetic background (agr allele). During November 2006, 235 strains were collected (wound infection: 51%, abscess: 21%, whitlow: 8%, diabetic foot: 7%, furunculosis: 3%). sea, tst and pvl were identified in 22.1, 13.2 and 8.9% strains, respectively. agr allele 1 was the most frequently encountered genetic background, whatever the methicillin susceptibility. Among the 34 methicillin-resistant S. aureus (MRSA, 14.5% of all S. aureus), only one strain (2.9%) harboured pvl (belonging to the European ST80 clone), four (11.8%) tst (belonging to two endemic French clones) and 18 (52.9%) sea gene (mainly the Lyon clone). According to their in vitro activity, pristinamycin or trimethoprim/sulfamethoxazole could be considered as first-choice antibiotics. To date, the international pvl-positive MRSA clones have not spread in France. MRSA strains isolated from putative CA-SSTIs exhibited a genetic and phenotypic background of hospital-acquired (HA) clones. National survey should be continued, in order to monitor the emergence of virulent clones.

High prevalence of methicillin-resistant Staphylococcus aureus clone ST80-IV in hospital and community settings in Algiers

USA300 is an epidemic community-acquired methicillin-resistant Staphylococcus aureus (C-MRSA) clone in the USA, whereas the European C-MRSA clone ST80-IV has mainly a sporadic diffusion in Europe. The prevalence of European clone ST80-IV in Algeria is poorly documented. We prospectively studied S. aureus infections at Mustapha Bacha hospital in Algiers over a 20-month period. S. aureus nasal colonization was studied during a further 6-month period. The European clone ST80-IV was responsible for more than one-third of both community infections (35.7%) and hospital infections (35.8%). Panton-Valentine leukocidin (PVL)-positive MRSA isolated from hospital inpatients were resistant to multiple antibiotics, including fluoroquinolones in 44.9% of cases. The PVL-positive MRSA nasal carriage rate was high among patients and staff in the dermatology unit (8.7% and 18.5%, respectively), but low (2.7%) among patients attending the outpatient clinic. The European PVL-positive C-MRSA clone ST80-IV is widespread in the Algiers hospital and community settings.

Pragmatic management of Panton-Valentine leukocidin-associated staphylococcal diseases

Panton-Valentine leukocidin (PVL)-producing Staphylococcus aureus is associated with a broad spectrum of diseases, ranging from common uncomplicated soft tissue infections to severe diseases such as complicated soft tissue infections, extensive bone and joint infections, and necrotising pneumonia. Specialised management of infection based on the presence of PVL may not be required for mild infections, whereas it could be lifesaving in other settings. Moreover, most severe PVL diseases are recently identified entities and a 'gold standard' treatment from comparatives studies of different therapeutic options is lacking. Thus, recommendations are based on expert opinions, which are elaborated based on theory, in vitro data and analogies with other toxin-mediated diseases. In this review, we consider the potential need for specialised PVL-based management and, if required, which tools should be used to achieve optimal management.

Panton-Valentine leukocidin-positive Staphylococcus aureus strains are associated with follicular skin infections

BACKGROUND/AIMS

Panton-Valentine leukocidin (PVL)-positive Staphylococcus aureus have been associated with suppurative infections; however, their precise role in skin infections has not been elucidated. We studied the rate of PVL-positive S. aureus in the different types of skin infections and compared follicular to nonfollicular skin infections.

METHODS

In our institution, patients with a skin infection caused by S. aureus were enrolled in a prospective, observational cohort study (from July 1, 2003 to June 30, 2010). We studied the rate of PVL-positive S. aureus in the different clinical types of skin infections and compared the rate of PVL-positive S. aureus in follicular infections to that in nonfollicular infections.

RESULTS

A total 229 skin infections were included: 97 (42.5%) were caused by PVL-positive strains. Thirty-nine of the 53 (74%) follicular infections [8 of the 17 (47%) with folliculitis, 30 of the 35 (85.5%) with furuncles and 1 with a carbuncle (100%)] were caused by PVL-positive S. aureus, compared to 16 of the 131 (12%) nonfollicular infections (p < 0.001).

CONCLUSION

PVL-positive S. aureus strains are mainly associated with follicular skin infections.

Clinical manifestations and outcome of skin infections caused by the community-acquired methicillin-resistant Staphylococcus aureus clone ST80-IV

BACKGROUND

Several Panton-Valentin leukocidin-positive clones of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are spreading worldwide. The European clone ST80-IV is the main CA-MRSA clone in Europe. There is no reported study of the specific clinical manifestations and outcome of skin infections caused by the clone ST80-IV, using strict definitions of skin diseases.

METHODS

Single-centre observational prospective cohort of S. aureus skin infections caused by the clone ST80-IV.

RESULTS

From November 1999 to October 2009, we diagnosed skin infections due to the clone ST80-IV in 20 patients (median age 28 years, median 27; range 1-66). All the isolates had all the following characteristics: lukPV, etd and edin gene-positive, agr 3 allele, spa-type t044 and ST80. All the isolates were resistant to beta-lactam agents, kanamycin, tetracycline and fusidic acid. During the study period, the 20 patients had the following manifestations: 19 primary abscesses (18 single abscess and one patient with two), eight furuncles, four folliculitis, one case of cellulitis, one wound infection and one felon. Surgical treatment and drainage was required for all the primary abscesses. The infections occurred mainly in the perineal area (50%). No secondary infections occurred in family members. Despite strict hygiene measures, systemic antibiotics and nasal mupirocine, four patients (20%) had recurrent skin infections over a period of a few months to 6 years.

CONCLUSIONS

The CA-MRSA clone ST80-IV is responsible for suppurative skin infections such as furuncles and abscesses, which can recur over a period of several years.

Diagnosis and treatment of spontaneous group A streptococcal peritonitis

BACKGROUND

Primary group A streptococcal peritonitis (PSAP) is a rare, fulminant and often fatal infection. The clinical manifestations include diffuse peritoneal signs with toxic shock syndrome and sometimes fasciitis.

METHODS

Patients with PSAP diagnosed between December 2002 and December 2006 were studied retrospectively, focusing on the initial presentation, diagnosis, treatment and outcome.

RESULTS

Six patients were identified (five women and one man). The clinical presentation was heterogeneous. All six patients had diffuse peritonitis, four had toxic shock syndrome on hospital admission and two patients also had fasciitis. All patients were treated surgically, and the final diagnosis was confirmed after operation. There were no deaths, but two patients had aesthetic sequelae owing to necrotizing fasciitis.

CONCLUSION

PSAP is a rare condition, often requiring aggressive surgical treatment. Group A streptococcal peritonitis should be suspected in patients with no radiological evidence of a peritoneal portal of entry and no history of ascites.

Primary skin abscesses are mainly caused by Panton-Valentine leukocidin-positive Staphylococcus aureus strains

BACKGROUND

The role of Panton-Valentine leukocidin (PVL) in skin and soft-tissue infections is not clear.

OBJECTIVE

Our purpose was to determine the prevalence of PVL gene carriage among Staphylococcus aureus strains isolated from primary and secondary skin abscesses.

METHODS

A prospective study was conducted. From July 2003 to June 2008, S. aureus isolates from skin abscesses were screened for the PVL genes. The abscesses were considered primary if they occurred on previously healthy skin and secondary in all other cases.

RESULTS

Fifty-seven patients presenting with S. aureus skin abscesses were included in the study. The PVL genes were detected in 40 (70%) of the 57 S. aureus isolates. Thirty-eight (92.7%) of the 41 primary skin abscesses were due to PVL-positive strains, compared to only 2 (12.5%) of the 16 secondary skin abscesses (p < 0.001).

CONCLUSIONS

Primary skin abscesses are mainly caused by PVL-positive S. aureus strains.

Hemofiltration with the Cascade system in an experimental porcine model of septic shock

High-volume hemofiltration (HVHF) has been suggested as an adjuvant treatment of septic shock because of its capacities to remove inflammatory mediators from blood. Nevertheless, HVHF presents some important drawbacks, such as the depletion of low molecular weight molecules (nutriments, vitamins, trace elements and antibiotics) due to the high ultrafiltration rate, or the significant financial cost and nursing workload due to the frequent changes of large amounts of expensive sterile substitution fluids. A new hemofiltration system called "Cascade" has been developed, allowing very high ultrafiltration rates (120 mL/kg/h) limiting these drawbacks by using a special extracorporeal circuit. The objective of this study was to assess the technical feasibility of the Cascade system and to compare its hemodynamic impact to that of the standard HVHF system. Twenty sepsis-induced pigs were randomized in two groups: one group was hemofiltered with the standard HVHF system and the other with the Cascade system during a six-hour session. No technical problems were observed with the Cascade system during the experiment. At the end of the experiment, colloid requirements (989 +/- 355 mL vs. 1913 +/- 538 mL, P = 0.006), epinephrine requirements (0.82 +/- 0.42 mg vs. 3.27 +/- 3.02 mg, P < 0.001), lactic acidosis (pH = 7.33 +/- 0.08 vs. 7.10 +/- 0.07, P < 0.001) and mean pulmonary arterial pressure were less pronounced in the Cascade group. These results suggest that Cascade hemofiltration is technically feasible and safe. Moreover, compared with standard HVHF, it can reduce the severity of porcine septic shock.

Serum antibodies against Panton-Valentine leukocidin in a normal population and during Staphylococcus aureus infection

To determine whether Staphylococcus aureus Panton-Valentine leukocidin (PVL) is expressed during human infection, anti-PVL antibody titres were compared in patients with PVL-positive and PVL-negative staphylococcal infections, and in patients with no evidence of S. aureus infection. Patients with PVL-positive strains had higher levels of anti-PVL antibodies than individuals of both control groups. The median anti-PVL titre increased 8.6-fold during the course of PVL-positive infection and 1.4-fold during PVL-negative infection. These results indicate that only PVL-positive S. aureus strains elicit significant anti-PVL antibody production in humans, and demonstrate the production of PVL during PVL-positive S. aureus infection. The protective role of this immune response remains to be established.

The Panton-Valentine leukocidin vaccine protects mice against lung and skin infections caused by Staphylococcus aureus USA300

Methicillin-resistant Staphylococcus aureus is increasingly responsible for staphylococcal infections in the community. A large percentage of the community-acquired methicillin-resistant (CA-MRSA) strains in the USA produce Panton-Valentine leukocidin (PVL), which is associated with severe infections. The virulence of the clinical CA-MRSA strain USA300 was compared to that of its isogenic pvl-deleted mutant, and it was shown that PVL contributes to lung and muscle tissue destruction, respectively, in murine necrotizing pneumonia and skin infection models. Mice infected with the USA300 strain developed a dominant anti-PVL response. The PVL subunits were therefore tested as vaccinogens against this isolate, and their vaccine efficacy correlated with both the route of vaccination and infection. These data suggest that PVL is a virulence factor in murine CA-MRSA infections.