Novel Riboswitch Ligand Analogs as Selective Inhibitors of Guanine-Related Metabolic Pathways

Riboswitches are regulatory elements modulating gene expression in response to specific metabolite binding. It has been recently reported that riboswitch agonists may exhibit antimicrobial properties by binding to the riboswitch domain. Guanine riboswitches are involved in the regulation of transport and biosynthesis of purine metabolites, which are critical for the nucleotides cellular pool. Upon guanine binding, these riboswitches stabilize a 5′-untranslated mRNA structure that causes transcription attenuation of the downstream open reading frame. In principle, any agonistic compound targeting a guanine riboswitch could cause gene repression even when the cell is starved for guanine. Antibiotics binding to riboswitches provide novel antimicrobial compounds that can be rationally designed from riboswitch crystal structures. Using this, we have identified a pyrimidine compound (PC1) binding guanine riboswitches that shows bactericidal activity against a subgroup of bacterial species including well-known nosocomial pathogens. This selective bacterial killing is only achieved when guaA, a gene coding for a GMP synthetase, is under the control of the riboswitch. Among the bacterial strains tested, several clinical strains exhibiting multiple drug resistance were inhibited suggesting that PC1 targets a different metabolic pathway. As a proof of principle, we have used a mouse model to show a direct correlation between the administration of PC1 and the reduction of Staphylococcus aureus infection in mammary glands. This work establishes the possibility of using existing structural knowledge to design novel guanine riboswitch-targeting antibiotics as powerful and selective antimicrobial compounds. Particularly, the finding of this new guanine riboswitch target is crucial as community-acquired bacterial infections have recently started to emerge

Antimicrobial susceptibility patterns and characterization of clinical isolates of Staphylococcus aureus in KwaZulu-Natal province, South Africa

BACKGROUND: Antimicrobial resistance of Staphylococcus aureus especially methicillin-resistant S. aureus (MRSA) continues to be a problem for clinicians worldwide. However, few data on the antibiotic susceptibility patterns of S. aureus isolates in South Africa have been reported and the prevalence of MRSA in the KwaZulu-Natal (KZN) province is unknown. In addition, information on the characterization of S. aureus in this province is unavailable. This study investigated the susceptibility pattern of 227 S. aureus isolates from the KZN province, South Africa. In addition, characterization of methicillin-sensitive S. aureus (MSSA) and MRSA are reported in this survey. METHODS: The in-vitro activities of 20 antibiotics against 227 consecutive non-duplicate S. aureus isolates from clinical samples in KZN province, South Africa were determined by the disk-diffusion technique. Isolates resistant to oxacillin and mupirocin were confirmed by PCR detection of the mecA and mup genes respectively. PCR-RFLP of the coagulase gene was employed in the characterization of MSSA and MRSA. RESULTS: All the isolates were susceptible to vancomycin, teicoplanin and fusidic acid, and 26.9% of isolates studied were confirmed as MRSA. More than 80% of MRSA were resistant to at least four classes of antibiotics and isolates grouped in antibiotype 8 appears to be widespread in the province. The MSSA were also susceptible to streptomycin, neomycin and minocycline, while less than 1% was resistant to chloramphenicol, ciprofloxacin, rifampicin and mupirocin. The inducible MLS(B )phenotype was detected in 10.8% of MSSA and 82% of MRSA respectively, and one MSSA and one MRSA exhibited high-level resistance to mupirocin. There was good correlation between antibiotyping and PCR-RFLP of the coagulase gene in the characterization of MRSA in antibiotypes 1, 5 and 12. CONCLUSION: In view of the high resistance rates of MRSA to gentamicin, erythromycin, clindamycin, rifampicin and trimethoprim, treatment of MRSA infections in this province with these antibacterial agents would be unreliable. There is an emerging trend of mupirocin resistance among S. aureus isolates in the province. PCR-RFLP of the coagulase gene was able to distinguish MSSA from MRSA and offers an attractive option to be considered in the rapid epidemiological analysis of S. aureus in South Africa. Continuous surveillance on resistance patterns and characterization of S. aureus in understanding new and emerging trends in South Africa is of utmost importance

Calculated parenteral initial therapy of bacterial infections: Bacterial meningitis

This is the thirteenth chapter of the guideline "Calculated initial parenteral treatment of bacterial infections in adults - update 2018" in the 2nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience.Bacterial meningitis is a life-threatening infectious disease with high mortality and disability rates requiring prompt initiation of antimicrobial treatment to lower these rates.Dies ist das 13. Kapitel der von der Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) herausgegebenen S2k Leitlinie "Kalkulierte parenterale Initialtherapie bakterieller Erkrankungen bei Erwachsenen - Update 2018" in der 2. aktualisierten Fassung.Die bakterielle Meningitis ist eine lebensbedrohliche Infektionskrankheit mit hohen Mortalitäts- und Invaliditätsraten, die den sofortigen Beginn einer antimikrobiellen Behandlung erfordert, um diese Raten zu senken

Intestinal carriage of multidrug-resistant bacteria among healthcare professionals in Germany

Healthcare professionals (HCP) might be at increased risk of acquisition of multidrug-resistant bacteria (MDRB), i.e., methillicin-resistant Staphyl oc occus aureus (MRSA), vancomycin-resistant enterococci (VRE), and multidrug-resistant gram-negative bacteria (MDRGN) and could be an unidentified source of MDRB transmission.The aim of this study was to determine the prevalence as well as risk factors of MDRB colonization among HCP.HCP (n=107) taking part in an antibiotic stewardship program, were voluntarily recruited to perform a rectal swab and to fill in a questionnaire to identify risk factors of MDRB carriage, i.e. being physician, gender, travel abroad within the previous 12 months, vegetarianism, regular consumption of raw meat, contact to domestic animals, household members with contact to livestock, work or fellowship abroad, as well as medical treatment abroad and antibiotic therapy within the previous 12 months. Selective solid media were used to determine the colonization rate with MRSA, VRE and MDRGN. MDRGN were further characterized by molecular analysis of underlying beta-lactamases. None of the participants had an intestinal colonization with MRSA or VRE. 3.7% of the participants were colonized with extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae , predominantly bla CTX-M type. Neither additional flouroquinolone resistance nor carbapenem resistance was detected in any of these isolates. No risk factors were identified to have a significant impact of MDRB carriage among HCP.A colonization rate of 3.7% with ESBL-producing Enterobacteriaceae is of interest, but comparing it to previously published data with similar colonization rates in the healthy population in the same geographic area, it is probably less an occupational risk

Nach Feuchteschaden durch Schimmelpilzbefall eines Gebäudes verursachtes Building Related Illness (BRI) bei allen Mitgliedern einer Familie

Introduction: In 2010, dampness damage in a single-family house caused a massive mold infestation. In the further course, the 5 family members developed severe health problems. This report investigates the extent and cause of the water damage. In addition, the various visible fungal infestations were analyzed in a specialized laboratory.Results: Due to building construction errors, starting from the basement, an increased moisture penetration of the residential building was detected.Within 2 years, massive mold infestation occurred. In 2016, the following species were detected: Cladosporium sphaerospermum, Chaetomium globosum, Penicillium chrysogenum, Scopularis brevicaulis, Acremonium furculum, A. charticola and A. sclerotigenum, Trichomonascus apis Aspergillus versicolor and Debaryomyces hansenii . Additionally, different black molds were macroscopically detected.The severity of the disease process varied, probably due to the different daily exposure of the family members, and possibly influenced by age. The children presented acute episodes with nocturnal cough, associated with sleep disturbances and respiratory infections with severe rhinitis. In addition, general fatigue was noticeable. The course of the disease was complicated by recurrent nightly nosebleeds. The mother developed a much more severe course as chronic fatigue syndrome. Additionally, the following continuous complaints occurred: sore throat and headache, nocturnal irritable cough, chronic rhinitis, difficulty concentrating, increasing forgetfulness and word-finding disorders, cognitive impairment with reduced short-term memory, extremely dry eyes with red sclerae, morning stiffness, dyspnea, disturbed temperature regulation (chills), increased feeling of thirst, and menstrual disorders. The father's building-related illness (BRI) was comparatively mild due to much lower exposure, with nocturnal irritable cough, rhinitis, and marked fatigue. In 2018, after moving out of the house, the father was symptom-free after 2 weeks, the three children after 6 months, but the mother only after 18 months.Discussion: The symptoms are consistent with reports from the literature, according to which fatigue, sleep disturbances, lack of concentration and headache as well as recurrent infections of the upper respiratory tract are caused by microbial volatile organic compounds (MVOCs) released by molds. The association with recurrent nosebleeds in childhood has not been described in this form before. Conclusion: Since in all family members complete remission of symptoms occurred after cessation of the 6-year exposure, there is no doubt that the BRI was caused by the massive mold infestation.Einleitung: Im Jahr 2010 kam es auf Grund eines Feuchteschadens in einem Wohnhaus zu massivem Schimmelpilzbefall und im weiteren Verlauf bei der 5-köpfigen Familie zu zunehmenden gesundheitlichen Beschwerden. Aus diesem Anlass sollte eine Ursachenklärung mit Ermittlung des Ausmaßes des Wasserschadens und Differenzierung des optisch sichtbaren Pilzbefalls durchgeführt werden. Ergebnisse: Es konnte ausgehend vom Kellergeschoss eine baulich bedingte zunehmende Durchfeuchtung des Wohnhauses nachgewiesen werden. Innerhalb von 2 Jahren kam es zu massivem Schimmelpilzbefall. Im Jahr 2016 wurden folgende Species nachgewiesen: Cladosporium sphaerospermum, Chaetomium globosum, Penicillium chrysogenum, Scopularis brevicaulis, Acremonium furculum, A. charticola, d A. sclerotigenum, Trichomonascus apis Aspergillus versicolor und Debaryomyces hansenii . Zusätzlich waren makroskopisch verschiedene Schwarzschimmelspecies vertreten. Die Erkrankung war unterschiedlich schwer ausgeprägt, vermutlich bedingt durch die unterschiedliche tägliche Exposition der Familienmitglieder und möglicherweise altersabhängig beeinflusst. Bei den Kindern traten die Beschwerden in Form akuter Schübe mit nächtlichem Husten, verbunden mit Schlafstörungen und respiratorischen Infektionen mit starker Rhinitis auf. Zusätzlich war eine generelle Ermüdung auffällig. Der Krankheitsverlauf wurde durch nächtlich auftretendes rezidivierendes Nasenbluten kompliziert. Bei der Mutter entwickelte sich eine deutlich schwerere Verlaufsform in Form eines Chronic Fatigue Syndroms. Zusätzlich traten folgende Dauerbeschwerden auf: Hals- und Kopfschmerzen, nächtlicher Reizhusten, chronische Rhinitis, Konzentrationsschwierigkeiten, zunehmende Vergesslichkeit und Wortfindungsstörungen, kognitive Einschränkungen mit reduziertem Kurzzeitgedächtnis, extrem trockene Augen mit roten Skleren, morgendliche Steifigkeit, Dyspnoe, gestörte Temperaturregulierung (Frösteln), vermehrtes Durstgefühl und Störungen der Menstruation. Beim Vater war das BRI wegen deutlich geringerer Exposition vergleichsweise gering ausgeprägt mit nächtlichem Reizhusten, Rhinitis und ausgeprägter Müdigkeit. Nach dem Wechsel der Wohnung waren der Vater nach 2 Wochen, die drei Kinder nach 6 Monaten und die Mutter erst nach 18 Monaten beschwerdefrei. Diskussion: Das Beschwerdebild deckt sich mit Berichten aus der Literatur, wonach durch von Schimmelpilzen freigesetzte MVOCs Müdigkeit, Schlafstörungen, Konzentrationsschwäche und Kopfschmerz sowie rezidivierende Infektionen der oberen Atemwege verursacht werden. Die Vergesellschaftung mit rezidivierendem Nasenbluten im Kindesalter ist in dieser Form bisher nicht beschrieben. Schlussfolgerung: Da es nach der Unterbrechung der insgesamt über 6 Jahre währenden Exposition zur kompletten Remission der Beschwerden kam, gibt es keinen Zweifel daran, dass die BRI durch den massiven Schimmelpilzbefall ausgelöst worden ist

Anti-tubercular activity of a natural stilbene and its synthetic derivatives

Objectives: Tuberculosis (TB) and multidrug- and extensively drug-resistant TB in particular are remaining a major global health challenge and efficient new drugs against TB are needed. This study evaluated the anti-tubercular activity of a natural stilbene and its synthetic derivatives against M. tuberculosis .Methods: Isopropylstilbene and its synthetic derivatives were analyzed for their anti-tubercular activity against M. tuberculosis ATCC 27294 as well as multidrug- and extensively drug-resistant M. tuberculosis clinical isolates by using MGIT 960 instrumentation and EpiCenter software equipped with TB eXiST module. Cytotoxic effects of drug candidates were determined by a MTT dye reduction assay using A549 adenocarcinomic human alveolar basal epithelial cells.Results: Growth of M. tuberculosis ATCC 27294 was suppressed by the natural isopropylstilbene HB64 as well as synthetic derivatives DB56 and DB55 at 25 µg/ml. Growth of clinical isolates MDR and XDR M. tuberculosis was suppressed by HB64 at 100 µg/ml as well as by synthetic derivatives DB56 and DB55 at 50 µg/ml and 25 µg/ml, respectively. No anti-tubercular activity was demonstrated for synthetic derivatives DB53, EB251, and RB57 at 100 µg/ml. Toxicity in terms of IC50 values of HB64, DB55 and DB56 were 7.92 µg/ml, 12.15 µg/ml and 16.01 µg/ml, respectively.Conclusions: Synthetical derivatives of stilbene might be effective candidates as anti-tubercular drugs. However, toxicity of these substances as determined by IC50 values might limit therapeutic success in vivo . Further investigations should address lowering the toxicity for parenteral administration by remodeling stilbene derivatives

Calculated parenteral initial treatment of bacterial infections: Microbiology

This is the second chapter of the guideline "Calculated initial parenteral treatment of bacterial infections in adults - update 2018" in the 2nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience.Preliminary microbiological findings regarding the patient and their immediate environment are crucial for the calculation of treatment with antibiotics in each case, as well as the resistance situation of the ward on which the patient is being cared for. If such data is not available, regional or supra-regional data can be used as a fallback. This chapter describes the methods of susceptibility testing, informs about the resistance situation in Germany and describes the main resistance mechanisms of bacterial pathogens against antibiotics. Further, the chapter informs about collateral damage of antibiotics as well as medical measures against increasing resistance.Dies ist das zweite Kapitel der von der Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) herausgegebenen S2k Leitlinie "Kalkulierte parenterale Initialtherapie bakterieller Erkrankungen bei Erwachsenen - Update 2018" in der 2. aktualisierten Fassung.Entscheidend für die Kalkulation einer Therapie mit Antibiotika im Einzelfall sind vorausgehende mikrobiologische Befunde des Patienten selbst und seiner unmittelbaren Umgebung sowie die Resistenzsituation der Abteilung, in der der Patient versorgt wird. Sind solche Daten nicht verfügbar, kann auf regionale oder überregionale Daten zurückgegriffen werden. Dieses Kapitel beschreibt die Methoden der Empfindlichkeitsprüfung, informiert über die überregionale Resistenzsituation in Deutschland und beschreibt die wichtigsten Resistenzmechanismen bakterieller Krankheitserreger gegen Antibiotika. Ferner informiert das Kapitel über Kollateralschäden von Antibiotika sowie medizinische Maßnahmen gegen die zunehmende Resistenz