Multiresistant Gram-negative Bacteria Research Articles

Predominance of Multidrug-Resistant Gram-Negative Bacteria on Contaminated Surfaces at a Tertiary Hospital in Tanzania: A Call to Strengthening Environmental Infection Prevention and Control Measures.

The spreading of multidrug resistance (MDR) strains in the hospital settings via contaminated surfaces have been increasingly reported where Gram-negative bacteria have been implicated in causing most nosocomial infections. This study aimed to determine the rate of contamination with multi-resistant gram-negative bacteria in the hospital environment. A cross-sectional study was conducted at Muhimbili National Hospital paediatric department, between July and August 2020. Non-repetitive surface swab samples were collected from predefined surfaces and medical device surfaces, and cultured on MacConkey agar with and without antibiotics. Isolates were identified using biochemical test and tested for antibiotic susceptibility using the Kirby-Bauer disk diffusion method. The rate of hospital contamination with Gram-negative bacteria across the Pediatrics units was 30%, with a high rate observed in oncology units (34.8%) and the malnutrition/diarrhoea ward (32.1%). Sink/washing basin had the highest frequency of bacterial contamination (74.2%). We observed a high rate of ESBL (32.5%), with Acinetobacter baumannii, Klebsiella pneumoniae, and E. coli being the predominant ESBL-producing Gram-negative bacteria, while carbapenemase-producing Gram-negative bacteria was detected at 22.8%. Highest resistance rates (63-100%) were observed against ceftriaxone and trimethoprim-sulfamethoxazole. Up to 51% of the Gram-negative bacteria showed resistant to meropenem. MDR strains were detected in 61.4% of Gram-negative bacteria isolated. In conclusion, we observed a high rate of MDR bacteria contaminating hospital surfaces. The higher rate of MDR calls for a need to strengthen infectious prevention control measures, including cleaning practices in the hospital environment, to reduce the risk of transmission of resistant strains to patients and healthcare workers.

Risk of bloodstream infections in allogeneic hematopoietic cell transplant recipients according to gut mucosal colonization and fluoroquinolone implementation during neutropenia

Background . Higher rate of gram-negative bloodstream infections (BSI) have been recently documented from transplantation centers providing fluoroquinolone (FQ) prophylaxis. Aim . To define the incidence of BSI during neutropenia according to gut mucosal colonization with resistant gramnegative bacteria and FQ administration. Materials and methods . Of 284 allogeneic hematopoietic cell transplant recipients included in the study, 154 (54.2 %) were identified as colonized with resistant gram-negative bacteria, and 130 (45.8 %) patients as non-colonized. Resistant gram-negative bacteria included Enterobacterales with extended spectrum beta-lactamase production, carbapenem-resistant Enterobacterales, Stenotrophomonas maltophilia , and carbapenem-resistant strains of Pseudomonas aeruginosa . Colonized patients did not receive FQ prophylaxis (n = 147) except 7 patients who received FQ as sequential therapy due to residual inflammatory lung lesions. Among non-colonized patients 98 received FQ prophylaxis, whereas 32 did not. Results . Probability of gram-negative BSI (71.4 %; p <0.0001), and extended spectrum beta-lactamase-producing Enterobacterales BSI (57.1 %; p <0.0001) was significantly higher in colonized patients receiving FQ. No significant difference was found in probability of gram-positive BSI (p = 0.452). In multivariate analysis colonized patients with (hazard ratio (HR) 35.32; 95 % confidence interval (CI) 9.15–136.44; p <0.0001) or without FQ (HR 3.44; 95 % CI 1.15–10.31; p = 0.007), omission of FQ in non-colonized patients (HR 4.03; 95 % CI 1.08–15.00; p = 0.038), and active disease before allogeneic hematopoietic cell transplantation (HR 2.17; 95 % CI 1.03–4.63; p = 0.042) were associated with higher risk of gram-negative BSI, whereas mismatched unrelated donor transplantations were associated with higher gram-positive BSI risk (HR 3.84; 95 % CI 1.63–9.08; p = 0,009). Conclusion . Colonization with multiresistant gram-negative bacteria is a predictor of gram-negative BSI, including multiresistant pathogens, especially when FQ are prescribed during neutropenia, while in non-colonized patients FQ prophylaxis is an effective approach significantly reducing gram-negative BSI.

Detection of multiresistant Gram-Negative bacteria associated with the irrational disposal of Pharmaceutical Chemical Waste, establishing environmental toxic impact on aquatic ecosystems in Araruama- RJ

Detection of multiresistant Gram-Negative bacteria associated with the irrational disposal of Pharmaceutical Chemical Waste, establishing environmental toxic impact on aquatic ecosystems in Araruama- RJ

Detection of colistin resistance via four methods in multidrug-resistant Gram-negative rods isolated from blood cultures.

The broth microdilution (BMD) method recommended for the detection of colistin resistance is labor-intensive, time-consuming, and difficult to apply in routine laboratories. Thus, various methods, such as disk elution, commercial microdilution, and rapid polymyxin-NP tests have been developed for the detection of colistin resistance. In this study, a total of 102 multi-resistant Gram-negative bacteria isolated from blood cultures were evaluated by four different methods for the detection of colistin resistance, and compared with the reference method. For the detection of the compatibility of these methods with the reference method, categorical and essential agreements, very major, major, and minor error rates were determined. Colistin-tigecycline and colistin-meropenem combinations were investigated in colistin-resistant isolates. Of the isolates, 15 (15%) [K. pneumoniae (n = 12), A. baumannii (n = 2), E. coli (n = 1)] were resistant to colistin with reference BMD method. MIC50 and MIC90 values of all isolates were ≤ 0.25 μg/mL and 16 μg/mL, respectively. The categorical agreement rates were 100% for commercial microdilution, disk elution, and RPNP test. The essential agreement rates of commercial microdilution, disk elution, and broth macrodilution were 78.4%, 86.3%, and 100%, respectively. Although there were no major errors in these methods, the macrodilution (12%) and commercial microdilution (20.6%) methods showed the most minor errors. Colistin-meropenem combination showed a 100% synergistic effect, but the colistin-tigecycline combination showed an 80% synergistic effect and 20% indifference effect. Disk elution and RPNP tests are suitable for routine use because they are the most efficient, easiest, low-cost, and good performance tests in detecting colistin resistance.

Visualisation of the transmission of microbial particles in the neonatal intensive care unit

Neonates in intensive care are vulnerable to colonisation and invasive infections from multi-resistant gram-negative bacteria [1]. In 2021 our neonatal unit (NNU) fell victim to an ESBL-Klebsiella outbreak. An outbreak control plan was formulated that included education; hand-hygiene and cleaning auditing; cohorting infants; mass screening infants and environment; and reduction of equipment in clinical areas. Our NNU has an active multidisciplinary simulation programme. Simulation is an effective educational tool to increase competence of healthcare providers [2]. We wanted to use simulation to highlight the ease of transmission of particles from a colonised infant. The simulation involved a preterm 28-week infant corrected to 35-week gestation with numerous desaturation episodes. The baby was known to be colonised with pseudomonas. A ‘monitored’ low-fidelity manikin was placed in a cot in an isolation room. Candidates were unaware that the manikin was covered with ultraviolet powder. The manikin had numerous desaturation and bradycardic episodes necessitating airway and breathing support, clinical assessment, and septic screen. The spread of powder was assessed afterwards with a black-light. The simulation lasted just 8 minutes. There were exemplary unprompted infection-prevention measures with appropriate handwashing and personal protective equipment. Despite this the powder spread to staff facemasks, stethoscope, resuscitation equipment, patient trolley, and monitor. This demonstrated the ease of transmission of particles to other surfaces despite adherence to infection prevention policies. Most striking was the transmission to candidates’ facemasks which are not routinely changed, and could be a potential risk of carriage of microbes to other infants. 1. Patel SJ, Green N, Clock SA, Paul DA, Perlman JM, Zaoutis T, Ferng YH, Alba L, Jia H, Larson EL, Saiman L. Gram-Negative Bacilli in Infants Hospitalized in The Neonatal Intensive Care Unit. J Pediatric Infect Dis Soc. 2017;6(3):227–230. 2. Aggarwal R, Mytton OT, Derbrew M, Hananel D, Heydenburg M, Issenberg B, MacAulay C, Mancini ME, Morimoto T, Soper N, Ziv A. Training and simulation for patient safety. BMJ Quality & Safety. 2010;19(Suppl 2):i34–43.

EPH128 Hospitalizations Caused By Infections with Carbapenem-Resistant, Gram-Negative Bacteria in Germany: An Epidemiologic Analysis Using Claims Data from Different Sources

Hospitalizations caused by infections with multiresistant gramnegative bacteria (in Germany 3 or 4MRGN) are of growing relevance also in the context of HTA for Ceftazidim Avibactam (CAZ/AVI). CAZ/AVI is part of the WHO reserve antibiotics group and is used in patients with 4MRGN infections. An extensive analysis using different data sources was performed to determine a realistic number of patients and hospital cases with these infections in Germany.

Use of the leaves of Alchornea cordifolia (Schumach. & Thonn.) Müll (Euphorbiaceae) and prospects for treatment of infections due to multidrug-resistant bacteria

BackgroundAfrica has a rich and diverse flora that people use for their food and health needs. This study aims to explore the possibility of using aqueous and/or ethanolic extracts of Alchornea cordifolia leaves as an alternative in the fight against multi-resistant bacteria responsible for gastritis and urinary tract infections.ResultsThe results show that 100% of the tested bacilli (E. coli, K. pneumoniae, P. aeruginosa) are resistant to the 10 antibiotic disks tested. This resistance is 66.66% for quinolones and fluoroquinolones. S. aureus was found to be resistant to glycopeptides and aminoglycosides. Three ESBL genes are identified in bacilli against only one type of ESBL gene in cocci. 100% of the bacilli carry the SHV genes, and S. aureus has the Mec A gene. The aqueous extract exerted a bactericidal effect on all the strains with MICs and BMCs varying, respectively, from 0.76 to 50 mg/ml and BMCs from 0.76 to 100 mg/ml. Only 40% of the chemical groups (tannin, flavonoids, mucilages and sterol-terpenes) sought were present in the aqueous extract. The ethanolic extract is not active.ConclusionsBased on these data, the aqueous extract of A. cordifolia leaves is a good phytomedical candidate for the treatment of gastritis (stomach cramps, watery or bloody diarrhea) and urinary tract infections caused by multi-resistant Gram-negative and Gram-positive bacteria.

Modes of action of the methanol extract and 3-O-[β-galactopyranosyl-(1→4)-β-D-galactopyranosyl]-oleanolic acid from Acacia polyacantha against multi-resistant Gram-negative bacteria

Background: Bacterial infections, especially those caused by multidrug-resistant (MDR) Gram-negative bacteria, remain a global health concern. Previous studies have reported the antibacterial activities of the methanol extract of the leaves of Acacia polyacantha Willd. (Fabaceae) (APL) as well as some of its phytoconstituents. In this study, APL and its constituent, 3-O-[β-galactopyranosyl-(1→4)-β-D-galactopyranosyl]-oleanolic acid (GGOA) were evaluated on growth kinetics, bacterial membrane, and H+-ATPase proton pumps. The acute toxicity of APL was also studied. Methods: The effects of APL and GGOA on bacterial growth kinetics and the bacterial membrane was determined using spectrophotometric methods. Their effects on the bacterial H+-ATPase proton pumps were evaluated through the acidification of the bacterial external environment using a pH-meter. The acute toxicity of APL was determined using the standard limit test method described by the Organization for Economic Cooperation and Development (OECD) code 425. Results: APL and GGOA modified the bacterial kinetics of Providencia stuartii ATCC29916 with emphasis on the latent phase. They blocked the proton pumps of this bacterium and destroy the bacterial membrane. The medium lethal dose (LD50) of APL was greater than 5000 mg/kg body weight (b.w.). Conclusion: The results of the present study provide important and complementary information on APL and GGOA as good antibacterial candidates for combating infections due to MDR Gram-negative bacteria. Keywords: 3-O-[β-galactopyranosyl-(1→4)-β-D-galactopyranosyl]-oleanolic acid; Acacia polyacantha; acute toxicity; Gram-negative bacteria; mode of action; multidrug resistance.

Aerosolized antibiotics – can they save us?

Introduction. In neonatal intensive care units, a serious complication for critical ill patients is represented by ventilator-associated pneumonia (VAP), most often caused by multiresistant Gram-negative bacteria. The treatment of this condition is very challenging, and neonatologists must take into consideration the side effects of broad-spectrum intravenous medications. According to different studies, aerosolized antibiotics could be efficient and safe for treating pulmonary infections in newborns. Case presentation. We report three cases of two extremely low birth weight (ELBW) premature babies and one late preterm with asphyxia who required long-term ventilatory support and who subsequently developed VAP, with the aggravation of their condition. Cultures from tracheal aspirates identified multiresistant Acinetobacter baumannii, rising issues regarding the therapeutic strategy. Colistin is a drug known to be active on most species of Acinetobacter in vitro, but for small premature babies there are concerns regarding its nephro- and neurotoxicity. Therefore, we chose to treat our patients with inhalatory colistimethate sodium for 14-21 days, given twice a day, as monotherapy in one case and as adjunctive therapy in the others, with clinical and bacteriological resolution. All babies could have been extubated and had a good respiratory outcome. Conclusions. In newborns with multiresistant VAP, aerosolized antibiotics can be beneficial and without systemic effects. The doses and regimens are yet to be standardized, but our experience confirms the studies that demonstrate this is a valid treatment which can be used alone or in association with intravenous antibiotics.

Phenotypical and genotypical assessment of resistance of carbapenemase producing Klebsiella pneumoniae strains

Introduction. The emergence and global spread of antimicrobial resistance genes, such as genes for extended-spectrum beta-lactamases and carbapenemases in Klebsiella pneumoniae strains, poses a significant threat to public health. The reason for this is that carbapenems are the latest therapeutic agent used to treat diseases caused by multi-resistant gram-negative bacteria. The detection of carbapenemases is epidemiologically important because ESBL-genes are plasmid-mediated and can be transmitted horizontally among different bacterial species. The aim of this research was to assess the spectrum of antibiotic resistance of carbapenemase-producing strains of K. pneumoniae circulating in hospitals in St. Petersburg using phenotypic and genotypic methods. Materials and methods. The susceptibility of K. pneumoniae strains (n=182), isolated from samples from patients admitted to hospitals in St. Petersburg in the period from 2016 to 2018, was assessed with 16 antimicrobials. Resistance to antibiotics was assessed by the gradient diffusion method. Carbapenemase genes were detected by molecular (PCR) and phenotypic (CIM) methods. Results. Most of the strains demonstrated a high percentage of resistance to ticarcillin/clavulanate (96.7%), quinolones (nalidixic acid (91.8%), norfloxacin (91.2%), ciprofloxacin (90.1%), ofloxacin (89%)), III and IV generation cephalosporins (cefotaxime (92.9%), ceftazidime (88.5%), cefoperazone (87.9%), ceftriaxone (86.8%), cefepime (91.2%)), netilmicin (83.5%) and gentamicin (80.2%). The investigated strains showed moderate resistance to amikacin (74.2%), meropenem (72.5%) and imepenem (65.9%). The main type of carbapenemases produced by the studied isolates of K. pneumoniae were NDM metallo-beta-lactamases (60.4%) and OXA-48 serine carbapenemases (49.5 %). KPC carbapenemases were found in only 1.1% of the strains. Discussion. The results of the study demonstrate a high resistance level of K. pneumoniae nosocomial isolates to various antibiotics. Therefore, the range of antimicrobials for treatment of Klebsiella infections is significantly reduced, which can lead to a decrease in the effectiveness of clinical therapy. Acknowledgments. The study had no sponsorship. Conflict of interest. The authors declare no apparent or potential conflicts of interest related to the publication of this article.

Detrimental Effect of Ozone on Pathogenic Bacteria.

(1) Background: Disinfection of medical devices designed for clinical use associated or not with the growing area of tissue engineering is an urgent need. However, traditional disinfection methods are not always suitable for some biomaterials, especially those sensitive to chemical, thermal, or radiation. Therefore, the objective of this study was to evaluate the minimal concentration of ozone gas (O3) necessary to control and kill a set of sensitive or multi-resistant Gram-positive and Gram-negative bacteria. The cell viability, membrane permeability, and the levels of reactive intracellular oxygen (ROS) species were also investigated; (2) Material and Methods: Four standard strains and a clinical MDR strain were exposed to low doses of ozone at different concentrations and times. Bacterial inactivation (cultivability, membrane damage) was investigated using colony counts, resazurin as a metabolic indicator, and propidium iodide (PI). A fluorescent probe (H2DCFDA) was used for the ROS analyses; (3) Results: No reduction in the count colony was detected after O3 exposure compared to the control group. However, the cell viability of E. coli (30%), P. aeruginosa (25%), and A. baumannii (15%) was reduced considerably. The bacterial membrane of all strains was not affected by O3 but presented a significant increase of ROS in E. coli (90 ± 14%), P. aeruginosa (62.5 ± 19%), and A. baumanni (52.6 ± 5%); (4) Conclusion: Low doses of ozone were able to interfere in the cell viability of most strains studied, and although it does not cause damage to the bacterial membrane, increased levels of reactive ROS are responsible for causing a detrimental effect in the lipids, proteins, and DNA metabolism.

Visualizing the Potential Impairment of Polymyxin B to Central Nervous System Through MR Susceptibility-Weighted Imaging.

Polymyxin B (PMB) exert bactericidal effects on the cell wall of Gram-negative bacteria, leading to changes in the permeability of the cytoplasmic membrane and resulting in cell death, which is sensitive to the multi-resistant Gram-negative bacteria. However, the severe toxicity and adverse side effects largely hamper the clinical application of PMB. Although the molecular pathology of PMB neurotoxicity has been adequately studied at the cellular and molecular level. However, the impact of PMB on the physiological states of central nervous system in vivo may be quite different from that in vitro, which need to be further studied. Therefore, in the current study, the biocompatible ultra-uniform Fe3O4 nanoparticles were employed for noninvasively in vivo visualizing the potential impairment of PMB to the central nervous system. Systematic studies clearly reveal that the prepared Fe3O4 nanoparticles can serve as an appropriate magnetic resonance contrast agent with high transverse relaxivity and outstanding biosafety, which thus enables the following in vivo susceptibility-weighted imaging (SWI) studies on the PMB-treated mice models. As a result, it is first found that the blood-brain barrier (BBB) of mice may be impaired by successive PMB administration, displaying by the discrete punctate SWI signals distributed asymmetrically across brain regions in brain parenchyma. This result may pave a noninvasive approach for in-depth studies of PMB medication strategy, monitoring the BBB changes during PMB treatment, and even assessing the risk after PMB successive medication in multidrug-resistant Gram-negative bacterial infected patients from the perspective of medical imaging.

Fusaricidins, Polymyxins and Volatiles Produced by Paenibacillus polymyxa Strains DSM 32871 and M1.

Paenibacilli are efficient producers of potent agents against bacterial and fungal pathogens, which are of great interest both for therapeutic applications in medicine as well as in agrobiotechnology. Lipopeptides produced by such organisms play a major role in their potential to inactivate pathogens. In this work we investigated two lipopeptide complexes, the fusaricidins and the polymyxins, produced by Paenibacillus polymyxa strains DSM 32871 and M1 by MALDI-TOF mass spectrometry. The fusaricidins show potent antifungal activities and are distinguished by an unusual variability. For strain DSM 32871 we identified numerous yet unknown variants mass spectrometrically. DSM 32871 produces polymyxins of type E (colistins), while M1 forms polymyxins P. For both strains, novel but not yet completely characterized polymyxin species were detected, which possibly are glycosylated. These compounds may be of interest therapeutically, because polymyxins have gained increasing attention as last-resort antibiotics against multiresistant pathogenic Gram-negative bacteria. In addition, the volatilomes of DSM 32781 and M1 were investigated with a GC–MS approach using different cultivation media. Production of volatile organic compounds (VOCs) was strain and medium dependent. In particular, strain M1 manifested as an efficient VOC-producer that exhibited formation of 25 volatiles in total. A characteristic feature of Paenibacilli is the formation of volatile pyrazine derivatives.

New insights about the EptA protein and its correlation with the pmrC gene in polymyxin resistance in Pseudomonas aeruginosa.

Nowadays, clinical and scientific interest in antibiotics, as polymyxin, has increased due to the large number of reports of multiresistant Gram-negative bacteria, as Pseudomonas aeruginosa. The aim of this study was to investigate a related group of proteins for resistance to polymyxins, encoded by P. aeruginosa genome, through in silico analysis. The mobilized colistin resistance 1 (MCR1) protein from Escherichia coli was used for comparison. Similar sequences to the protein MCR1 in P. aeruginosa were analysed for physicochemical properties. 31 protein isoforms in P. aeruginosa (EptA) were found able to confer resistance to polymyxin showing protein lengths between 551 and 572 amino acids, with molecular mass values between 61.36 - 62. 80kDa, isoelectric point between 6.10 to 7.17, instability index between 33.76 to 41.87, aliphatic index between 98.67 to 102.63 and the hydropathyindex between - 0.008 to 0.094. These proteins belong to the DUF1705 superfamily with bit-score values between 559.81 and 629.78. A high degree of similarity between EpTAs in P. aeruginosa was observed in relation to other proteins that confer resistance to polymyxins, present in Gram-negative bacteria species of clinical interest. Although, further studies are needed to identify the actual contribution of EptAs in P. aeruginosa species.

Efficacy of aerosolized hydrogen peroxide (Deprox) cleaning compared to physical cleaning in a Burns Unit

The performance of Deprox aerosolized hydrogen peroxide (aHP) has not been extensively studied in real-world clinical settings. A comparative study of aHP terminal disinfection was conducted in a Burns Unit and its performance compared to physical cleaning alone. Environmental surfaces were sampled pre-cleaning, post-cleaning and post-aHP disinfection. Samples were cultured for MRSA, VRE, Gram-negative multi-resistant organisms and other Gram-negative bacilli. 310 sites were sampled. There was a reduction in the rates of contaminated surfaces post-aHP, though pathogens were still recoverable in most cases, except for VRE. There was a marked reduction in MRSA contamination of soft surfaces (12% post-clean vs 6% post-aHP), and patient room surfaces (8.3% post-clean vs 2.8% post-aHP). It does not work as well for MRSA in bathrooms: 7% of surfaces were positive post-clean, and 9% post-aHP. There was a reduction in multiresistant Gram-negative bacteria (7%-3%), mostly due to drains (33%-13%). aHP is a useful method of environmental disinfection, especially for Gram-negative pathogens in drains and MRSA on hard and soft surfaces. Where ongoing acquisition of MRSA is a problem, an adjunctive method of terminal disinfection in bathrooms could be considered.

Antibiotic resistance markers are a necessary tool in many clinical areas

Antibiotic resistance (AR) is one of the leading and still far from solving the problems of mankind. Implementation of strategies for controling AR at different levels is a priority task, since crisis of the possibilities of creating new antibiotics is obvious. Implementation of this strategy in the medical field consists in the rational use of antibacterial agents and hygienic control of the spread of multiresistant strains.One of the ways to rationalize the use of antimicrobial agents was WHO AWaRe classification, the purpose of which is to expand the use of narrow-spectrum antibiotics and limit the misuse of reserve groups and drugs with growing resistance levels. Implementation of these tasks is impossible without microbiological studies. Laboratory diagnostics of the infectious causes has undergone significant improvement – automation, availability of routine determination of resistance markers. The review presents the main mechanisms of AR development by common pathogens and possibility of their reflection in resistance markers.An important milestone in 2020 was the Infectious Diseases Society of America (IDSA) clinical guideline for treatment of infectious caused by common multi-resistant gram-negative bacteria. In contrast to previous clinical guidelines, this makes the prescription of antibacterial drugs primarily on information about resistance markers, antibiotic susceptibility, and also on the location of infection. The purpose of the IDSA-2020 clinical guidelines is to assist clinicians in making decisions in treatment of infections caused by extended-spectrum β-lactamase or carbapenemase-producing Enterobacteriaceae bacteria and Pseudomonas feruginosa multi-drug resistant. The review presents the main points of this clinical guideline.Thus, effective treatment of infections caused by antibiotic-resistant microorganisms is possible due to contemporary microbiological methods according to evidence-based clinical guidelines. Automated microbiological research systems significantly expand the clinical possibilities of effective treatment of infections and epidemiological control of resistant strains.

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.

Phenotypic characterization of the resistance of Salmonella – Shigella isolates to colistin and detection of mcr1/2 genes

Objective: Colistin is one of the latest line of therapeutics used in the management of infections due to multiresistant Gram-negative bacteria. The current emergence of colistin resistance, in particular through the mediation of plasmid resistance genes (mcr1 and mcr2) in intestinal bacteria is a worldwide concern. The objective of this study is to evaluate the sensitivity of Salmonella and Shigella strains to colistin and the detection of mcr1 and mcr2 genes within these strains. Methodology and Results: The colistin sensitivity profile of 30 Salmonella strains and 5 Shigella strains was determined using the Minimum Inhibitory Concentrations in liquid medium of Mueller Hinton and the results were interpreted in accordance with the standards of the European Committee on Antimicrobial Susceptibility Testing Epidemiological cut-off 2020 version 10.0. Finally, the mcr1 and mcr2 genes were detected by a conventional PCR. Overall, a phenotypic resistance rate of 20% was recorded for Salmonella-Shigella pathogens, with a frequency of 17.1% for Salmonella and 2.9% for Shigella. Molecular screening of these isolates revealed a lack of detection of the mcr1 and mcr2 genes in their genetic heritage. Conclusion and application of results: this study shows that Salmonella and Shigella strains are resistant to colistin, however the mcr 1 and 2 genes have not been amplified. To this end, the rational use of colistin must be applied in the human and animal field in order to curb the increase and spread of resistance to this molecule. Keywords: Colistin, Gabon, mcr, resistance, Salmonella-Shigella

Prevalence of multiresistant gram-negative bacteria in inhabitants of long-term care facilities in 2019 in Thuringia

Multidrug-resistant gram-negative bacteria (MDRGN) pose an emerging threat in German hospitals and in the outpatient sector. However, only few studies have investigated the prevalence of MDRGN in nonhospital settings and the associated risk factors for colonization. In our study we determined the prevalence of MDRGN in inhabitants of long-term care facilities (LTCFs) and associated risk factors for colonization in the region Weimar, Weimarer Land, and Jena. Between May and August 2019, deep rectal swabs were taken from 307 inhabitants of 13facilities and examined microbiologically for the presence of MDRGN. Furthermore, using astandardized questionnaire, the characteristics of the inhabitants were collected and their association with the likelihood for colonization with MDRGN was analyzed. MDRGN were found in 59swabs, predominantly Escherichia coli (95%). The weighted prevalence of extended spectrum beta-lactamase-producing bacteria was 19.1% and for MDRGN with additional resistances to fluoroquinolones was 12.3%. Resistances to carbapenems or carbapenemases were not found. Multivariable as well as univariable analysis recognized the presence of chronic wounds to be apotential risk factor (OR: 2,66 [95 %-CI: 1,54-4,60]). Additionally, the univariable analysis detected the necessity of awheelchair and the accommodation in double rooms as risk factors. The prevalence of MDRGN found in our study is similar to findings of previous German studies. The result shows the importance of strict compliance with basic hygiene guidelines for all inhabitants of LTCFs for the prevention of transmission of MDRGN.

Alternative drugs against multiresistant Gram-negative bacteria

ObjectivesEnterobacterales and other non-fermenting Gram-negative bacteria have become a threat worldwide owing to the frequency of multidrug resistance in these pathogens. On the other hand, efficacious therapeutic options are quickly diminishing. The aims of this study were to describe the susceptibility of 50 multiresistant Gram-negative bacteria, mostly pan-resistant, against old and less-used antimicrobial drugs and to investigate the presence of antimicrobial resistance genes. MethodsA total of 50 genetically distinct isolates were included in this study, including 14 Acinetobacter baumannii (belonging to ST79, ST317, ST835 and ST836), 1 Pseudomonas aeruginosa (ST245), 8 Serratia marcescens and 27 Klebsiella pneumoniae (belonging to ST11, ST340, ST258, ST16, ST23, ST25, ST101, ST234, ST437 and ST442). The isolates were submitted to antimicrobial susceptibility testing and whole-genome sequencing to evaluate lineages and resistance genes. ResultsOur results showed that some strains harboured carbapenemase genes, e.g. blaKPC-2 (28/50; 56%) and blaOXA-23 (11/50; 22%), and other resistance genes encoding aminoglycoside-modifying enzymes (49/50; 98%). Susceptibility rates to tigecycline (96%) in all species (except P. aeruginosa), to minocycline (100%) and doxycycline (93%) in A. baumannii, to ceftazidime/avibactam in S. marcescens (100%) and K. pneumoniae (96%), and to fosfomycin in S. marcescens (88%) were high. Chloramphenicol and quinolones (6% susceptibility each) did not perform well, making their use in an empirical scenario unlikely. ConclusionsThis study involving genetically distinct bacteria showed promising results for tigecycline for all Gram-negative bacteria (except P. aeruginosa), and there was good activity of minocycline against A. baumannii, ceftazidime/avibactam against Enterobacterales, and fosfomycin against S. marcescens.