Luzia Veletzky

Daptomycin plus Fosfomycin, a Synergistic Combination in Experimental Implant-Associated Osteomyelitis Due to Methicillin-Resistant Staphylococcus aureus in Rats

ABSTRACT The aim of this study was to evaluate the combination of daptomycin and fosfomycin in experimental chronic implant-associated osteomyelitis due to methicillin-resistant Staphylococcus aureus (MRSA). Infection was induced in the tibiae of rats by the insertion of a bacterial inoculum (1 to 5 × 108 CFU/ml) of a clinical MRSA isolate and a titanium wire. Four weeks after infection, each animal was assigned to a treatment group: daptomycin monotherapy at 60 mg/kg of body weight once daily (n = 10), fosfomycin monotherapy at 40 mg/kg once daily (n = 10), or daptomycin and fosfomycin combined at 60 mg/kg and 40 mg/kg, respectively, once daily (n = 9). Ten animals were left untreated. After a 3-week treatment period, the animals were euthanized, and the infected tibiae and implants were processed for quantitative bacterial cultures. The bacterial cultures from bones were positive for MRSA in all animals in the untreated group, the daptomycin group, and the fosfomycin group, with median bacterial counts of 2.34 × 106 CFU/g bone, 1.57 × 106 CFU/g bone, and 3.48 × 102 CFU/g bone, respectively. In the daptomycin-fosfomycin group, 6 out of 9 animals were positive for MRSA, with a median count of 7.92 CFU/g bone. Bacterial cultures derived from the titanium wires were negative in the fosfomycin- and daptomycin-fosfomycin-treated groups. Based on bacterial counts in bones, treatment with daptomycin-fosfomycin was statistically significantly superior to all that of the other groups (P ≤ 0.003). Fosfomycin was superior to daptomycin and no treatment (P < 0.0001). No development of resistance was observed in any treatment arm. The combination of daptomycin and fosfomycin demonstrated synergism against MRSA in experimental implant-associated osteomyelitis.

Use of Capillary Blood Samples Leads to Higher Parasitemia Estimates and Higher Diagnostic Sensitivity of Microscopic and Molecular Diagnostics of Malaria Than Venous Blood Samples

Background Diagnosis of malaria is usually based on samples of peripheral blood. However, it is unclear whether capillary (CAP) or venous (VEN) blood samples provide better diagnostic performance. Quantitative differences of parasitemia between CAP and VEN blood and diagnostic performance characteristics were investigated. Methods Patients were recruited between September 2015 and February 2016 in Gabon. Light microscopy and quantitative polymerase chain reaction (qPCR) measured parasitemia of paired CAP and VEN samples. CAP and VEN performance characteristics using microscopy were evaluated against a qPCR gold standard. Results Microscopy revealed a median parasitemia of 495/μL in CAP and 429/μL in VEN samples, manifesting in a 16.6% (P = .04) higher CAP parasitemia compared with VEN parasitemia. Concordantly, in qPCR -0.278 (P = .006) cycles were required for signal detection in CAP samples. CAP sensitivity of microscopy relative to the gold standard was 81.5% vs VEN sensitivity of 73.4%, while specificities were 91%. CAP and VEN sensitivities dropped to 63.3% and 45.9%, respectively, for a subpopulation of low-level parasitemias, whereas specificities were 92%. Conclusions CAP sampling leads to higher parasitemias compared to VEN sampling and improves diagnostic sensitivity. These findings may have important implications for routine diagnostics, research, and elimination campaigns of malaria.

Efficacy and Safety of Fosmidomycin–Piperaquine as Nonartemisinin-Based Combination Therapy for Uncomplicated Falciparum Malaria: A Single-Arm, Age De-escalation Proof-of-Concept Study in Gabon

Fosmidomycin–piperaquine is being developed as nonartemisinin-based combination therapy to meet the challenge of emerging artemisinin resistance. The combination appeared to have high efficacy and be safe and well tolerated despite observed transient changes in electrocardiogram with prolongation of the QT interval.

Zika virus-induced itching rash in a returning traveller from Brazil.

• Zika virus infections are an important differential diagnosis in febrile patients returning from endemic areas.

Validity and reliability of methods to microscopically detect and quantify malaria parasitaemia

The recommended microscopy method by WHO to quantify malaria parasitaemia yields inaccurate results when individual leucocyte (WBC) counts deviate from 8000 leucocytes/μl. A method avoiding WBC count assumptions is the Lambaréné method (LAMBA). Thus, this study compared validity and reliability of the LAMBA and the WHO method.

Detection of the Malaria causing Plasmodium Parasite in Saliva from Infected Patients using Topoisomerase I Activity as a Biomarker

Malaria is among the major threats to global health with the main burden of disease being in rural areas of developing countries where accurate diagnosis based on non-invasive samples is in high demand. We here present a novel molecular assay for detection of malaria parasites based on technology that may be adapted for low-resource settings. Moreover, we demonstrate the exploitation of this assay for detection of malaria in saliva. The setup relies on pump-free microfluidics enabled extraction combined with a DNA sensor substrate that is converted to a single-stranded DNA circle specifically by topoisomerase I expressed by the malaria causing Plasmodium parasite. Subsequent rolling circle amplification of the generated DNA circle in the presence of biotin conjugated deoxynucleotides resulted in long tandem repeat products that was visualized colorimetrically upon binding of horse radish peroxidase (HRP) and addition of 3,3′,5,5′-Tetramethylbenzidine that was converted to a blue colored product by HRP. The assay was directly quantitative, specific for Plasmodium parasites, and allowed detection of Plasmodium infection in a single drop of saliva from 35 out of 35 infected individuals tested. The results could be determined directly by the naked eye and documented by quantifying the color intensity using a standard paper scanner.

Dalbavancin for treatment of implant-related methicillin-resistant Staphylococcus aureus osteomyelitis in an experimental rat model

Dalbavancin is a new semisynthetic lipoglycopeptide with improved antimicrobial activity against various gram-positive pathogens. It demonstrates an extensive plasma half-life which permits outpatient parenteral antimicrobial therapy with weekly intervals and might therefore be an excellent treatment alternative for patients requiring prolonged antimicrobial therapy. The present study investigated dalbavancin monotherapy in an experimental implant-related methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis model. A clinical MRSA isolate and a Kirschner-wire were inserted into the proximal tibia of anaesthetized Sprague-Dawley rats. Four weeks after infection 34 animals were treated over 4 weeks with either dalbavancin (20 mg/kg loading-dose; 10 mg/kg daily), vancomycin (50 mg/kg twice daily) or left untreated. Twenty-four hours after the last treatment dose tibial bones and Kirschner-wires were harvested for microbiological examination. Based on quantitative bacterial cultures of osseous tissue, dalbavancin was as effective as vancomycin and both were superior to no treatment. No emergence of an induced glycopeptide-/lipoglycopeptide- resistance was observed after a treatment period of four weeks with either dalbavancin or vancomycin. In conclusion, monotherapy with dalbavancin was shown to be as effective as vancomycin for treatment of experimental implant-related MRSA osteomyelitis in rats, but both antimicrobials demonstrated only limited efficacy. Further studies are warranted to evaluate the clinical efficacy of dalbavancin for the treatment of periprosthetic S. aureus infections.

Molecular evidence for relapse of an imported Plasmodium ovale wallikeri infection

BackgroundMalaria caused by Plasmodium ovale spp. has been neglected by and large from research and has received only little scientific attention during the past decades. Ovale malaria is considered to feature relapses by liver hypnozoites although scientific evidence for this paradigm is scarce.Case presentationHere, the case of a 16-year-old male, who presented with fevers to the outpatient department in Vienna, Austria, after travelling to Uganda and Papua New Guinea is described. Infection with Plasmodium malariae was diagnosed by microscopy and the patient was treated accordingly with a full course of supervised artemether–lumefantrine. He was discharged in good clinical condition with a negative blood smear. One month after initial diagnosis, he returned complaining of fever. Thick blood smear was positive again for malaria parasites, which were confirmed as P. ovale wallikeri by PCR. Retrospective analysis revealed the identical Plasmodium spp. in the initial blood samples. Molecular analysis of various gene loci (nuclear porbp2, 18S rRNA and potra genes) gave identical results providing further evidence for relapse by an identical parasite genotype. Consecutively, the patient was retreated with artemether–lumefantrine and received a regimen of primaquine according to WHO guidelines.ConclusionConclusive evidence for relapses with P. ovale spp. is rare. The presented case provides convincing confirmation for the relapse paradigm based on re-appearing parasitaemia following supervised treatment in a non-endemic region with a parasite strain of identical genotype.

Behavioural and clinical predictors for Loiasis

Background Loiasis is a vector-borne disease in Central and West Africa. While there is still uncertainty to what extent loiasis is responsible for population morbidity, individuals having both loiasis and onchocerciasis have a high risk of fatal encephalopathy when treatment (ie, ivermectin) for onchocerciasis is given. Therefore it is current policy that communities of high loiasis-burden are excluded from mass drug administration programmes of ivermectin. To address this treatment gap we present diagnostic scores, based on clinical and behavioural predictors that may help to rapidly identify sub-groups with loiasis within high-burden communities. Methods A cross-sectional survey was performed in the province of la Ngounie, Gabon between December 2015 and Februrary 2016 and 947 participants of all ages were recruited. Clinical parameters and behavioural exposure factors were ascertained by questionnaire-based interviews. Parasitological analysis of blood samples was performed for L. loa detection. Diagnostic scores consisting of clinical and behavioural factors were modelled to predict loiasis in sub-groups residing in endemic regions. Results Increasing sylvan exposure was identified as important risk factor for loiasis with adjusted odds ratios of 5.1 (95% confidence interval CI 2.6-9.9) for occasional forest exposure, 11.1 (95% CI 5.4-22.6) for frequent forest exposure and 25.7 (95% CI 12.5-52.9) for intensive forest exposure. Individuals with loiasis were 7.7 (95% CI 5.4-11.0) times more likely to report recurrent pruritus than those without loiasis. Reporting of regular daily exposure to the deep rain forest and recurrent pruritus was 9-fold (positive likelihood ratio 9.18; 95% CI: 6.39-13.18) more prevalent in individuals with loiasis than in controls. Concordantly, the absence of regular weekly forest exposure was associated with extremely low disease-likelihood (negative likelihood ratio 0.09; 95% CI 0.05-0.16). Conclusions These composite scores may serve as a simple tool to rapidly identify both those most and those least at risk of disease and may simplify loiasis control activities as well as screening procedures for studies on loiasis. Further, they may aid policy-makers to tailor the delivery of ivermectin mass drug administration for onchocerciasis control programmes more effectively and safely in regions of high loiasis-burden.

Artemether-lumefantrine for the treatment of Plasmodium malariae, Plasmodium ovale, and mixed Plasmodium malaria: A prospective clinical trial assessing species-specific efficacy in Gabon

ABSTRACT Treatment recommendations for Plasmodium malariae and Plasmodium ovale malaria are largely based on anecdotal evidence. The aim of this prospective study, conducted in Gabon, was to systematically assess the efficacy and safety of artemether-lumefantrine for the treatment of patients with uncomplicated P. malariae or P. ovale species monoinfections or mixed Plasmodium infections. Patients with microscopically confirmed P. malariae, P. ovale, or mixed-species malaria with at least one of these two Plasmodium species were treated with an oral, fixed-dose combination of artemether-lumefantrine for 3 consecutive days. The primary endpoints were per-protocol PCR-corrected adequate clinical and parasitological response (ACPR) on days 28 and 42. Tolerability and safety were recorded throughout the follow-up period. Seventy-two participants (42 male and 30 female) were enrolled; 62.5% of them had PCR-corrected mixed Plasmodium infections. Per protocol, PCR-corrected ACPR rates were 96.6% (95% confidence interval [CI], 91.9 to 100) on day 28 and 94.2% (95% CI, 87.7 to 100) on day 42. Considering Plasmodium species independently from their coinfecting species, day 42 ACPR rates were 95.5% (95% CI, 89.0 to 100) for P. falciparum, 100% (exact CI, 84.6 to 100) for P. malariae, 100% (exact CI, 76.8 to 100) for P. ovale curtisi, and 90.9% (95% CI, 70.7 to 100) for P. ovale wallikeri. Study drug-related adverse events were generally mild or moderate. In conclusion, this clinical trial demonstrated satisfying antimalarial activity of artemether-lumefantrine against P. ovale wallikeri, P. ovale curtisi, P. malariae, and mixed Plasmodium infections, with per-protocol efficacies of 90% to 100% and without evident tolerability or safety concerns. (This trial was registered in the clinical study database ClinicalTrials.gov under the identifier NCT02528279.)