The Very First Modification of Pleuromutilin and Lefamulin by Photoinitiated Radical Addition Reactions—Synthesis and Antibacterial Studies

Pleuromutilin is a fungal diterpene natural product with antimicrobial properties, semisynthetic derivatives of which are used in veterinary and human medicine. The development of bacterial resistance to pleuromutilins is known to be very slow, which makes the tricyclic diterpene skeleton of pleuromutilin a very attractive starting structure for the development of new antibiotic derivatives that are unlikely to induce resistance. Here, we report the very first synthetic modifications of pleuromutilin and lefamulin at alkene position C19–C20, by two different photoinduced addition reactions, the radical thiol-ene coupling reaction, and the atom transfer radical additions (ATRAs) of perfluoroalkyl iodides. Pleuromutilin were modified with the addition of several alkyl- and aryl-thiols, thiol-containing amino acids and nucleoside and carbohydrate thiols, as well as perfluoroalkylated side chains. The antibacterial properties of the novel semisynthetic pleuromutilin derivatives were investigated on a panel of bacterial strains, including susceptible and multiresistant pathogens and normal flora members. We have identified some novel semisynthetic pleuromutilin and lefamulin derivatives with promising antimicrobial properties.

Skin tolerant inactivation of multiresistant pathogens using far-UVC LEDs

Multiresistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) cause serious postoperative infections. A skin tolerant far-UVC (< 240 nm) irradiation system for their inactivation is presented here. It uses UVC LEDs in combination with a spectral filter and provides a peak wavelength of 233 nm, with a full width at half maximum of 12 nm, and an irradiance of 44 µW/cm2. MRSA bacteria in different concentrations on blood agar plates were inactivated with irradiation doses in the range of 15–40 mJ/cm2. Porcine skin irradiated with a dose of 40 mJ/cm2 at 233 nm showed only 3.7% CPD and 2.3% 6-4PP DNA damage. Corresponding irradiation at 254 nm caused 15–30 times higher damage. Thus, the skin damage caused by the disinfectant doses is so small that it can be expected to be compensated by the skin's natural repair mechanisms. LED-based far-UVC lamps could therefore soon be used in everyday clinical practice to eradicate multiresistant pathogens directly on humans.

Implications of COVID-19 Pandemic on the Emergence of Antimicrobial Resistance: Adjusting the Response to Future Outbreaks

The net effect of the coronavirus disease 2019 (COVID-19) pandemic and the response to it on the emergence of antimicrobial resistance is yet unknown. Positive impacts on the spread of multiresistant pathogens and infections in general may be observed with the implementation of general preventative measures for the spread of infectious disease such as social distancing, reduced travel and increased personal hygiene. This pandemic has accelerated the development of novel technologies, such as mRNA vaccines, that may be used to fight other diseases. These should be capitalized upon to manage the ongoing antimicrobial resistance pandemic in the background. However, it is likely that the COVID-19 pandemic is fueling the emergence of antimicrobial resistance due to high rates of inappropriate antimicrobial prescribing, the high use of biocides and the interruption of treatment for other conditions. Clinical uncertainty driven by the lack of effective diagnostics and practice of telemedicine may have driven the inappropriate use of antimicrobials. As pathogens know no borders, increased focus is needed for infectious diseases still threatening low- and middle-income countries such as tuberculosis. Stewardship measures for future outbreaks should stress the importance of social distancing and hand washing but discourage the overuse of disinfectants and antimicrobials that are not proven effective.

Diclofenac May Induce PIA-Independent Biofilm Formation in Staphylococcus aureus Strains

Staphylococcus aureus is a pathogen commonly resistant to antibiotics. Biofilm formation is one of the important factors related to its virulence. Non-antibiotics drugs, such as nonsteroidal anti-inflammatory agents (NSAIDs), have been studied as an alternative for treating infections by multiresistant pathogens and biofilm-associated infections. In this study, the effects of NSAID sodium diclofenac on growth inhibition and biofilm formation of S. aureus were evaluated. The minimum inhibitory concentration (MIC) of diclofenac for fifty isolates ranged from 200 to 400 μg/mL. Diclofenac sub-MICs induced biofilm in 32.3% of biofilm-negative strains in tryptic soy broth. All biofilms induced by the drug showed a PIA- (polysaccharide intercellular adhesion-) independent composition, and the scanning electron microscopy showed that the induced biofilm presented a very discrete matrix. The combination of diclofenac with rifampicin sub-MICs induced strong production of PIA-dependent biofilm in three of four strains, while combination of NSAID with NaCl induced the formation of partially polysaccharide biofilm in two strains and PIA-independent biofilm in another strain. The combination of NSAID with glucose resulted in PIA-independent biofilms in all four strains tested. The results showed that diclofenac can commonly induce biofilm production by a PIA-independent pathway. However, when this NSAID is combined with other types of inducing agents, the composition of the biofilm produced may vary.

Multirezisztens kórokozók szűrése szürkehályog-műtét előtt

Összefoglaló. Bevezetés: A multirezisztens kórokozók által okozott fertőzések komoly gondot okoznak. Szemészeti szempontból az ebbe a körbe tartozó meticillinrezisztens Staphylococcus aureus (MRSA) baktérium bír kiemelkedő jelentőséggel. Célkitűzés: Multirezisztens kórokozók irányában cataractaműtét előtt álló betegektől mintavétel és adatelemzés. Módszer: 257, cataractaműtét előtt álló beteg esetében végeztünk multirezisztens kórokozók szűrésére vizsgálatot a conjunctivazsákból. A mikrobiológiai tenyésztés során multirezisztens kórokozóra pozitív eredményt adó betegek esetében a preoperatív kórtörténetet és az általános kísérő betegségeket feltártuk és elemeztük. Eredmények: A minták 17 beteg esetében multirezisztens kórokozóra pozitívak voltak. 11 esetben szisztémás rizikófaktorokat is találtunk. A pozitív betegeknél a műtétet csak a felszabadító mikrobiológiai eredmények birtokában végeztük el. A dekolonizált betegeknél ezt követően a szakmai protokoll normális antibiotikumprevencióját alkalmaztuk. A 257 beteg 6,6%-ában találtunk multirezisztenskórokozó- és 5%-ában MRSA-pozitivitást. Posztoperatív endophthalmitis nem fordult elő. Következtetés: A cataractaműtéteknél alkalmazott antibiotikus endophthalmitisprevenció multirezisztens kórokozóra pozitív betegeknél kevéssé hatékony lehet. Ezért javasolt a veszélyeztetett betegek multirezisztens kórokozókra történő szűrése és dekolonizációja. Orv Hetil. 2021; 162(3): 106–111. Summary. Introduction: Infections caused by multiresistant pathogens may have serious consequences. In ophthalmological practice, methicillin-resistant Staphylococcus aureus (MRSA) is the most important multiresistant pathogen. Objective: We took samples for multiresistant pathogens from patients assigned for cataract surgery. Method: We carried out multiresistant pathogen screening from conjunctival sac in 257 patients, who were assigned for cataract surgery. Preoperative case history and concomitant systemic diseases were evaluated in patients, who turned out to be positive for multiresistant pathogens during the screening procedure. Results: The samples were positive for multiresistant pathogens in 17 patients. In the case history of 11 multiresistant pathogen positive patients, previous systemic risk factors could be explored. Multiresistant pathogen positive patients were operated only after the decolonisation. After the decolonisation, the normal antibiotic prevention was used before the surgery. Multiresistant pathogen positive was 6.6%, MRSA positive was 5% of the 257 patients. There were no cases of endophthalmitis in any of these patients. Conclusion: Endophthalmitis prevention with antibiotics, according to the guidelines, may not be efficient in multiresistant pathogen positive patients. Therefore, it is advisable to screen multiresistant pathogens and decolonisation at risk patients before cataract surgery. Orv Hetil. 2021; 162(3): 106–111.

Detection of the main multiresistant microorganisms in the environment of a teaching veterinary hospital in Brazil

ABSTRACT: Contamination of the veterinary hospital environment with multiresistant pathogens endangers not only hospitalized animals, but also the workplace safety of veterinarians and nurses, animal guardians and, when in case of a teaching hospital, veterinary students. The objective of this study was to map the main points of bacterial contamination of a veterinary teaching hospital in Brazil to identify multiresistant microorganisms and their antimicrobial resistance genes. Samples were collected from 39 different locations of a veterinary school hospital which comprised a pool according to each hospital environment. In certain environments, more than one pool has been collected. All samples were collected in quadruplicates for the selective isolation of the main multiresistant microorganisms: methicillin-resistant Staphylococcus (MRS), vancomycin resistant Enterococcus (VRE), cephalosporinases and/or extended-spectrum beta-lactamase-producing Gram-negative bacteria (ESBL) and Carbapenemase-producing (CP). After isolation and identification of isolates, multiplex-PCR reactions were performed to detect the main genes for each microorganism and antimicrobial susceptibility tests with the main antibiotics used for each bacterial group according to CLSI. Of the 39 veterinary teaching hospital sites collected, all (100%) had at least one of the microorganisms surveyed, and 17.95% (n=7) of the sites were able to isolate the four pathogens. From the 94 pools collected, it was possible to isolate MRS in 81.91% (n=77), VRE in 12.77% (n=12), cephalosporinases and/or ESBL in 62.77% (n=59) and CP in 24.47%. (n=23). Regarding MRS, the mecA gene was detected in all isolates. All isolated VREs were identified as Enterococcus faecalis and presented the vanA gene. Regarding cephalosporinases and/or ESBL, 89.83% (n=53) of the isolates presented the blaTEM gene, 57.63% (n=34) the blaOXA-1 gene, 37.29% (n=22) blaCTX-M gene from some group (1, 2, 9 ou 8/25) and 20.34% (n=12) the blaSHV gene. It was possible to identify the main microorganisms responsible for causing nosocomial infections in humans (VRE, MRS, ESBL and CP) in the veterinary hospital environment, suggesting a source of infection for professionals and students of veterinary medicine, placing a high risk for public health.

The Isolation of a Novel Streptomyces sp. CJ13 from a Traditional Irish Folk Medicine Alkaline Grassland Soil that Inhibits Multiresistant Pathogens and Yeasts

The World Health Organization recently stated that new sources of antibiotics are urgently required to stem the global spread of antibiotic resistance, especially in multiresistant Gram-negative bacteria. Although it was thought that many of the original sources of antibiotics were exhausted, innovative research has revealed promising new sources of antibiotic discovery in traditional medicine associated with Streptomyces. In this work we investigated the potential of a specific limestone grassland soil, associated with Irish folk medicine, as a new source of antimicrobial discovery. Using selective enrichment and isolation techniques on a limestone grassland soil sample obtained from Boho, West Fermanagh, we isolated Streptomyces sp. CJ13. This bacterium inhibited the growth of a broad range of pathogens in vitro including Gram positive Staphylococcus aureus (MRSA 43300) and Gram negative multiresistant Pseudomonas aeruginosa (PA01), as well as the anaerobic bacteria Propionibacterium acnes and the yeast Starmerella bombicola. Genome sequencing and phylogenetic analysis revealed Streptomyces sp. CJ13 to be closely related to an unclassified Streptomyces sp. MJM1172, Streptomyces sp. Mg1 and two species known as Streptomyces sp. ICC1 and ICC4 from a karst region in British Columbia. The closest type species to Streptomyces sp. CJ13 was Streptomyces lavendulae subspecies lavendulae. Analysis of Streptomyces sp. CJ13 whole genome sequence using the secondary metabolite prediction tool antiSMASH revealed similarities to several antibiotic gene synthesis clusters including salinichelin, mediomycin A, weishanmycin, combamide, heat stable antifungal factor and SAL-2242. These results demonstrate the potential of this alkaline grassland soil as a new resource for the discovery of a broad range of antimicrobial compounds including those effective against multiresistant Gram negative bacteria.

Challenges in Bone Tissue Regeneration: Stem Cell Therapy, Biofunctionality and Antimicrobial Properties of Novel Materials and Its Evolution

An aging population leads to increasing demand for sustained quality of life with the aid of novel implants. Patients expect fast healing and few complications after surgery. Increased biofunctionality and antimicrobial behavior of implants, in combination with supportive stem cell therapy, can meet these expectations. Recent research in the field of bone implants and the implementation of autologous mesenchymal stem cells in the treatment of bone defects is outlined and evaluated in this review. The article highlights several advantages, limitations and advances for metal-, ceramic- and polymer-based implants and discusses the future need for high-throughput screening systems used in the evaluation of novel developed materials and stem cell therapies. Automated cell culture systems, microarray assays or microfluidic devices are required to efficiently analyze the increasing number of new materials and stem cell-assisted therapies. Approaches described in the literature to improve biocompatibility, biofunctionality and stem cell differentiation efficiencies of implants range from the design of drug-laden nanoparticles to chemical modification and the selection of materials that mimic the natural tissue. Combining suitable implants with mesenchymal stem cell treatment promises to shorten healing time and increase treatment success. Most research studies focus on creating antibacterial materials or modifying implants with antibacterial coatings in order to address the increasing number of complications after surgeries that are mostly caused by bacterial infections. Moreover, treatment of multiresistant pathogens will pose even bigger challenges in hospitals in the future, according to the World Health Organization (WHO). These antibacterial materials will help to reduce infections after surgery and the number of antibiotic treatments that contribute to the emergence of new multiresistant pathogens, whilst the antibacterial implants will help reduce the amount of antibiotics used in clinical treatment.

Prognosis and effectiveness of antibacterial treatment of endometritis after cesarian section with isolating drug-resistent ESKAPE pathohens

Purpose. The purpose of this study was to determine the frequency of isolation of drug-resistant ESKAPE pathogens isolation in endometritis after cesarean section; to assess the prognosis of the disease and the effectiveness of initial empirical antimicrobial therapy for isolating multiresistant pathogens. Methods. A retrospective analysis of all the cases of endometritis after cesarean section in St. Petersburg was performed. The study period: September 2008 September 2019. Results. 68 (26.7%) out of 255 cases of endometritis after cesarean section were caused by pathogens of the rESKAPE group. In puerperas with endometritis caused by rESKAPE pathogens, the following are more often observed: clinical failures in prescribing initial empirical antimicrobial therapy compared with endometritis of another etiology (p = 0.0012); severe course of infectious process with the risk of its generalization and hysterectomy (p 0.05). Conclusions. Endometritis after abdominal delivery caused by rESKAPE pathogens is associated with an unfavorable prognosis of the disease and a high risk of ineffective antimicrobial therapy.

Modelling pathogen spread in a healthcare network: Indirect patient movements

Inter-hospital patient transfers (direct transfers) between healthcare facilities have been shown to contribute to the spread of pathogens in a healthcare network. However, the impact of indirect transfers (patients re-admitted from the community to the same or different hospital) is not well studied. This work aims to study the contribution of indirect transfers to the spread of pathogens in a healthcare network. To address this aim, a hybrid network–deterministic model to simulate the spread of multiresistant pathogens in a healthcare system was developed for the region of Lower Saxony (Germany). The model accounts for both, direct and indirect transfers of patients. Intra-hospital pathogen transmission is governed by a SIS model expressed by a system of ordinary differential equations. Our results show that the proposed model reproduces the basic properties of healthcare-associated pathogen spread. They also show the importance of indirect transfers: restricting the pathogen spread to direct transfers only leads to 4.2% system wide prevalence. However, adding indirect transfers leads to an increase in the overall prevalence by a factor of 4 (18%). In addition, we demonstrated that the final prevalence in the individual healthcare facilities depends on average length of stay in a way described by a non-linear concave function. Moreover, we demonstrate that the network parameters of the model may be derived from administrative admission/discharge records. In particular, they are sufficient to obtain inter-hospital transfer probabilities, and to express the patients’ transfers as a Markov process. Using the proposed model, we show that indirect transfers of patients are equally or even more important as direct transfers for the spread of pathogens in a healthcare network.