Efficacy of cloxacillin versus cefazolin for methicillin-susceptible Staphylococcus aureus bacteraemia (CloCeBa): study protocol for a randomised, controlled, non-inferiority trial

INTRODUCTION

Methicillin-susceptible Staphylococcus aureus (MSSA) bacteraemia is a common and severe disease responsible for approximately 65 000 deaths every year in Europe. Intravenous antistaphylococcal penicillins (ASP) such as cloxacillin are the current recommended antibiotics. However, increasing reports of toxicity and recurrent stock-outs of ASP prompted healthcare providers to seek for alternative antibiotic treatment. Based on retrospective studies, cefazolin, a first-generation cephalosporin, is recommended in patients at risk of severe ASP-associated toxicity.We hypothesised that cefazolin has a non-inferior efficacy in comparison to cloxacillin, with a better safety profile for the treatment of MSSA bacteraemia.

METHODS AND ANALYSIS

The CloCeBa trial is an open-label, randomised, controlled, non-inferiority trial conducted in academic centres throughout France. Eligible patients are adults with MSSA bacteraemia without intravascular device or suspicion of central nervous system infection. Patients will be randomised (1:1) to receive either cloxacillin or cefazolin by the intravenous route, for the first 14 days of therapy. The evaluation criteria is a composite criteria of negative blood cultures at day 5, survival, absence of relapse and clinical success at day 90 after randomisation. Secondary evaluation criteria include both efficacy and safety assessments. Three ancillary studies are planned to describe the epidemiology of β-lactamase encoding genes, the ecological impact and pharmacokinetic/pharmacodynamic parameters of cefazolin and cloxacillin. Including 300 patients will provide 80% power to demonstrate the non-inferiority of cefazolin over cloxacillin, assuming 85% success rate with cloxacillin and taking into account loss-to-follow-up, with a 0.12 non-inferiority margin and a one-sided type I error of 0.025.

ETHICS AND DISSEMINATION

This protocol received authorisation from the ethics committee Sud-Est I on 13 November 2017 (2017-87-PP)and French National Agency for Medicines and Health Products (170661A-43). Results will be disseminated to the scientific community through congresses and publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03248063 and 2017-003967-36.

Association between biofilm formation phenotype and clonal lineage in Staphylococcus aureus strains from bone and joint infections

Biofilm formation is a critical virulence factor responsible for treatment failure and chronicity in orthopaedic device-related infections (ODIs) caused by Staphylococcus aureus. Clonal lineages differ in terms of their biofilm forming capacities. The aim of this study was to investigate the correlation between the clonal complex (CC) affiliation and biofilm phenotype of 30 clinical S. aureus isolates responsible of ODI based on i) early biofilm formation using BioFilm Ring Test® and mature biofilm formation using crystal violet assays, ii) biofilm composition using DNase and proteinase K activity, and iii) prevention of biofilm formation by cloxacillin, teicoplanin and vancomycin using Antibiofilmogram® (biofilm minimal inhibitory concentration–bMIC). In terms of early biofilm formation, the CC30 strains were significantly slower than the CC5, CC15 and CC45 strains. CC45 strains produced significantly more mature biofilm than other group of strains did. The formation of biofilms was highly dependent on the presence of extracellular DNA in the CC5, CC15 and CC30 strains whereas it was mostly dependent on the presence of proteins in CC45. Finally, the CC30 group highlighted higher proportion of susceptible (bMIC < breakpoints of EUCAST guidelines) for cloxacillin, teicoplanin and vancomycin compared to the other CCs. These results demonstrate that the biofilm phenotype of clinical S. aureus isolates from ODIs is strongly related to their respective CC affiliation.

Should we expand the indications for the DAIR (debridement, antibiotic therapy, and implant retention) procedure for Staphylococcus aureus prosthetic joint infections? A multicenter retrospective study

To evaluate factors associated with failure in patients treated with DAIR (debridement, antibiotic therapy, and implant retention) for Staphylococcus aureus prosthetic joint infections (PJIs). We retrospectively analyzed consecutive patients with stable PJI due to S. aureus treated with DAIR at six hospitals between 2010 and 2014. Cox proportional hazards regression was used to study factors associated with treatment failure at 2 years. Of 154 eligible patients, 137 were included (mean age 73 ± 13 years; male 56%). The estimated success rate according to the Kaplan-Meier method was 76.2 [95% CI 68-83] at 2 years of follow-up. In multivariate analysis, longer duration of treatment (hazard ratio (HR) 0.78 [0.69-0.88]; p < 0.001) and combination therapy including rifampin (HR 0.08 [0.018-0.36]; p = 0.001) were independently associated with success, whereas active smoking was independently associated with failure (HR 3.6 [1.09-11.84]; p = 0.036). When the analysis was restricted to patients with early infection onset (< 3 months), early acute infection was also predictive of a better prognosis (HR 0.25 [0.09-0.7]; p = 0.009). Failure was not associated with time from prosthesis insertion to debridement, nor with duration of symptoms > 3 weeks and type of prosthesis (hip or knee). These results remained unchanged when the 14 patients under immunosuppressive therapy were removed from analysis. These data suggest that DAIR can be performed even if infection and symptoms are delayed but reserved to patients who are able to follow rifampin-based combination therapy for a prolonged duration that should not be different for hip and knee PJI.

Molecular characterization of Treponema pallidum subsp. pallidum in Switzerland and France with a new multilocus sequence typing scheme

Syphilis is an important public health problem and an increasing incidence has been noted in recent years. Characterization of strain diversity through molecular data plays a critical role in the epidemiological understanding of this re-emergence. We here propose a new high-resolution multilocus sequence typing (MLST) scheme for Treponema pallidum subsp. pallidum (TPA). We analyzed 30 complete and draft TPA genomes obtained directly from clinical samples or from rabbit propagated strains to identify suitable typing loci and tested the new scheme on 120 clinical samples collected in Switzerland and France. Our analyses yielded three loci with high discriminatory power: TP0136, TP0548, and TP0705. Together with analysis of the 23S rRNA gene mutations for macrolide resistance, we propose these loci as MLST for TPA. Among clinical samples, 23 allelic profiles as well as a high percentage (80% samples) of macrolide resistance were revealed. The new MLST has higher discriminatory power compared to previous typing schemes, enabling distinction of TPA from other treponemal bacteria, distinction between the two main TPA clades (Nichols and SS14), and differentiation of strains within these clades.

Impact of baseline plasma HIV-1 RNA and time to virological suppression on virological rebound according to first-line antiretroviral regimen

Objectives

We investigated the risk of virological rebound in HIV-1-infected patients achieving virological suppression on first-line combined ART (cART) according to baseline HIV-1 RNA, time to virological suppression and type of regimen.

Patients and methods

Subjects were 10 836 adults who initiated first-line cART (two nucleoside or nucleotide reverse transcriptase inhibitors + efavirenz, a ritonavir-boosted protease inhibitor or an integrase inhibitor) from 1 January 2007 to 31 December 2014. Cox proportional hazards models with multiple adjustment and propensity score matching were used to investigate the effect of baseline HIV-1 RNA and time to virological suppression on the occurrence of virological rebound.

Results

During 411 436 patient-months of follow-up, risk of virological rebound was higher in patients with baseline HIV-1 RNA ≥100 000 copies/mL versus <100 000 copies/mL, in those achieving virological suppression in > 6 months versus <6 months, and lower with efavirenz or integrase inhibitors than with ritonavir-boosted protease inhibitors. Baseline HIV-1 RNA >100 000 copies/mL was associated with virological rebound for ritonavir-boosted protease inhibitors but not for efavirenz or integrase inhibitors. Time to virological suppression >6 months was strongly associated with virological rebound for all regimens.

Conclusions

In HIV-1-infected patients starting cART, risk of virological rebound was lower with efavirenz or integrase inhibitors than with ritonavir-boosted protease inhibitors. These data, from a very large observational cohort, in addition to the more rapid initial virological suppression obtained with integrase inhibitors, reinforce the positioning of this class as the preferred one for first-line therapy.

Complex ecological interactions of Staphylococcus aureus in tampons during menstruation

Menstrual toxic shock syndrome (mTSS) is a severe disease that occurs in healthy women vaginally colonized by Staphylococcus aureus producing toxic shock toxin 1 and who use tampons. The aim of the present study was to determine the impact of the composition of vaginal microbial communities on tampon colonisation by S. aureus during menses. We analysed the microbiota in menstrual fluids extracted from tampons from 108 healthy women and 7 mTSS cases. Using culture, S. aureus was detected in menstrual fluids of 40% of healthy volunteers and 100% of mTSS patients. Between class analysis of culturomic and 16S rRNA gene metabarcoding data indicated that the composition of the tampons' microbiota differs according to the presence or absence of S. aureus and identify discriminating genera. However, the bacterial communities of tampon fluid positive for S. aureus did not cluster together. No difference in tampon microbiome richness, diversity, and ecological distance was observed between tampon vaginal fluids with or without S. aureus, and between healthy donors carrying S. aureus and mTSS patients. Our results show that the vagina is a major niche of. S. aureus in tampon users and the composition of the tampon microbiota control its virulence though more complex interactions than simple inhibition by lactic acid-producing bacterial species.

Microbiologic epidemiology depending on time to occurrence of prosthetic joint infection: a prospective cohort study

OBJECTIVES

The high microbiologic diversity encountered in prosthetic joint infection (PJI) makes the choice of empirical antimicrobial therapies challenging, especially in cases of implant retention or one-stage exchange. Despite the risk of dysbiosis and toxicity, the combination of vancomycin with a broad-spectrum β-lactam is currently recommended in all cases, even if Gram-negative bacilli (GNB) might be less represented in late PJI. In this context, this study aimed to describe the microbiologic epidemiology of PJI according to the chronology of infection.

METHODS

This prospective cohort study (2011-2016) evaluated the microbiologic aetiology of 567 PJI according to time of occurrence from prosthesis implantation-early (<3 months), delayed (3-12 months) and late (>12 months)-as well as mechanism of acquisition.

RESULTS

Initial microbiologic documentation (n = 511; 90.1%) disclosed 164 (28.9%) Staphylococcus aureus (including 26 (16.1%) methicillin-resistant S. aureus), 162 (28.6%) coagulase-negative staphylococci (including 81 (59.1%) methicillin-resistant coagulase-negative staphylococci), 80 (14.1%) Enterobacteriaceae, 74 (13.1%) streptococci and 60 (10.6%) Cutibacterium acnes. Considering nonhaematogenous late PJI (n = 182), Enterobacteriaceae (n = 7; 3.8%) were less represented than in the first year after implantation (n = 56; 17.2%; p <0.001), without difference regarding nonfermenting GNB (4.6% and 2.7%, respectively). The prevalence of anaerobes (n = 40; 21.9%; including 32 (80.0%) C. acnes) was higher in late PJI (p <0.001). Consequently, a broad-spectrum β-lactam might be useful in 12 patients (6.6%) with late PJI only compared to 66 patients (20.3%) with early/delayed PJI (p <0.001).

CONCLUSIONS

Considering the minority amount of GNB in late postoperative PJI, the empirical use of a broad-spectrum β-lactam should be reconsidered, especially when a two-stage exchange is planned.

Prevalence and Risk Factors for Anal Human Papillomavirus Infection in Human Immunodeficiency Virus-Positive Men Who Have Sex with Men

Background

We assessed prevalence and risk factors for anal human papillomavirus (HPV) in human immunodeficiency virus (HIV)-positive men who have sex with men (MSM), who are at high-risk of HPV-related anal cancer.

Methods

APACHES is a multicentric, prospective study of anal HPV infection and lesions in HIV-positive MSM aged ≥35 years. At baseline, participants underwent anal swabs for HPV and cytology, plus high-resolution anoscopy. High-risk HPV (HR-HPV) was tested by Cobas4800, with genotyping of HR-HPV positives by PapilloCheck.

Results

Among 490 participants, prevalence of HPV16 and HR-HPV was 29% and 70%, respectively, and did not differ significantly by age, sexual behavior, or markers of HIV or immune deficiency. Smoking was the only, albeit weak (odds ratio, 1.8; 95% confidence interval, 1.2-2.7), predictor of HR-HPV. High-risk HPV and HPV16 prevalence increased strongly with anal diagnosis severity, both by worse cytological/histological (composite) diagnosis at APACHES baseline and worse historical diagnosis. HPV16 rose from 19% among participants who were negative for lesions to 63% among participants with high-grade lesions. In contrast, non-HPV16 HR-HPVs were less prevalent in high-grade (37%) than negative (64%) composite diagnosis, and their causal attribution was further challenged by multiple HPV infections.

Conclusions

Human papillomavirus 16 is ubiquitously frequent among human immunodeficiency virus -positive men having sex with men, and more strongly associated with high-grade anal lesions than other high-risk types, confirming it as a target for anal cancer prevention.

Pressure ulcer-related pelvic osteomyelitis: evaluation of a two-stage surgical strategy (debridement, negative pressure therapy and flap coverage) with prolonged antimicrobial therapy

Background

A two-stage surgical strategy (debridement-negative pressure therapy (NPT) and flap coverage) with prolonged antimicrobial therapy is usually proposed in pressure ulcer-related pelvic osteomyelitis but has not been widely evaluated.

Methods

Adult patients with pressure ulcer-related pelvic osteomyelitis treated by a two-stage surgical strategy were included in a retrospective cohort study. Determinants of superinfection (i.e., additional microbiological findings at reconstruction) and treatment failure were assessed using binary logistic regression and Kaplan-Meier curve analysis.

Results

Sixty-four pressure ulcer-related pelvic osteomyelitis in 61 patients (age, 47 (IQR, 36–63)) were included. Osteomyelitis was mostly polymicrobial (73%), with a predominance of S. aureus (47%), Enterobacteriaceae spp. (44%) and anaerobes (44%). Flap coverage was performed after 7 (IQR, 5–10) weeks of NPT, with 43 (68%) positive bone samples among which 39 (91%) were superinfections, associated with a high ASA score (OR, 5.8; p = 0.022). An increased prevalence of coagulase negative staphylococci (p = 0.017) and Candida spp. (p = 0.003) was observed at time of flap coverage. An ESBL Enterobacteriaceae spp. was found in 5 (12%) patients, associated with fluoroquinolone consumption (OR, 32.4; p = 0.005). Treatment duration was as 20 (IQR, 14–27) weeks, including 11 (IQR, 8–15) after reconstruction. After a follow-up of 54 (IQR, 27–102) weeks, 15 (23%) failures were observed, associated with previous pressure ulcer (OR, 5.7; p = 0.025) and Actinomyces spp. infection (OR, 9.5; p = 0.027).

Conclusions

Pressure ulcer-related pelvic osteomyelitis is a difficult-to-treat clinical condition, generating an important consumption of broad-spectrum antibiotics. The lack of correlation between outcome and the debridement-to-reconstruction interval argue for a short sequence to limit the total duration of treatment.

Intraosteoblastic activity of daptomycin in combination with oxacillin and ceftaroline against MSSA and MRSA

BACKGROUND

The Staphylococcus aureus intracellular reservoir is associated with bone and joint infection (BJI) chronicity. As daptomycin is increasingly prescribed in BJI, strategies for improving its reduced intracellular activity should be promoted.

OBJECTIVES

Based on the known in vitro synergy of daptomycin with β-lactams, the aim of the present study was to evaluate the intracellular activity of these combinations in an ex vivo osteoblast infection model.

METHODS

Osteoblastic cells infected with an MRSA strain or its isogenic MSSA counterpart were incubated for 24 h with daptomycin, oxacillin or ceftaroline alone or in combination using usual intraosseous therapeutic concentrations. Intracellular bacteria were quantified by plating cell lysates. MICs for MSSA and MRSA were determined using the chequerboard method at pH 5 to mimic conditions expected within lysosomes, the foremost S. aureus intracellular location.

RESULTS

Daptomycin failed to reduce the intracellular MSSA inoculum, and was weakly active against MRSA compared with untreated cells (-27.6%; P < 10-3). Oxacillin and ceftaroline revealed significant intracellular activity, including oxacillin against MRSA-infected cells (-43.2%; P < 10-3). The daptomycin/oxacillin combination was significantly more active against intracellular MSSA and MRSA compared with daptomycin and oxacillin alone (-44.4% and -57.2%, respectively; P < 0.05). In contrast, daptomycin/ceftaroline was not more efficient than ceftaroline alone. Interestingly, oxacillin MICs for MRSA decreased in vitro from >256 to 0.023 mg/L when the pH decreased from 7 to 5, and chequerboards showed an additive effect of the daptomycin/oxacillin combination against MRSA at pH 5.

CONCLUSIONS

In acidic intracellular conditions, oxacillin enhances daptomycin activity against the intraosteoblastic reservoir of S. aureus, including MRSA.