Phytochemical screening, toxicity and antimicrobial activity of different Mimosa tenuiflora extracts on Aeromonas strains

The indiscriminate use of synthetic veterinary drugs in fish farms for disease control has caused recurring environmental pollution and reduced productivity; however, the search for ecologically viable alternatives is increasing. Thus, this study aimed to evaluate the phytochemical characterization of the hexanic, methanolic, and aqueous extracts of black jurema (M. tenuiflora), and their antimicrobial activity against strains of Aeromonas, and acute toxicity (LC50) to fingerlings of O. niloticus. The isolates were identified, and phenotypic virulence and antimicrobial susceptibility tests were performed. A. caviae, and A. veronii bv. veronii showed 75.0 - 87.5% positivity for the virulence factors tested, and resistance to the antimicrobials ampicillin, amoxicillin, erythromycin, and tetracycline of 67.0% and 50.0%, respectively. Phytochemical screening of black jurema extracts detected phenols, flavonoids, tannins, saponins, alkaloids, and steroids/triterpenoids, with methanol proving to be more efficient in the extraction of metabolites. The methanolic and aqueous extracts showed moderate antimicrobial activity, with minimum inhibitory concentration and minimum bactericidal concentration of 250 μg mL-1, and the methanolic extract revealed an LC50 of 40 μg mL-1 for O. niloticus. This study demonstrated the efficiency of the in vitro antimicrobial activity of M. tenuiflora extracts, and their use in vivo in the treatment or prophylaxis in fish farming can be investigated to replace the use of synthetic antimicrobials.

Colistin Resistance Mechanisms in Human Salmonella enterica Strains Isolated by the National Surveillance Enter-Net Italia (2016–2018)

Background: A collection of human-epidemiologically unrelated S. enterica strains collected over a 3-year period (2016 to 2018) in Italy by the national surveillance Enter-Net Italia was analysed. Methods: Antimicrobial susceptibility tests, including the determination of minimal inhibitory concentrations (MICs) for colistin, were performed. Colistin resistant strains were analysed by PCR to detect mobile colistin resistance (mcr) genes. In mcr-negative S. enterica serovar Enteritidis strains, chromosomal mutations potentially involved in colistin resistance were identified by a genomic approach. Results: The prevalence of colistin-resistant S. enterica strains was 7.7%, the majority (87.5%) were S. Enteritidis. mcr genes were identified only in one strain, a S. Typhimurium monophasic variant, positive for both mcr-1.1 and mcr-5.1 genes in an IncHI2 ST4 plasmid. Several chromosomal mutations were identified in the colistin-resistant mcr-negative S. Enteritidis strains in proteins involved in lipopolysaccharide and outer membrane synthesis and modification (RfbN, LolB, ZraR) and in a component of a multidrug efflux pump (MdsC). These mutated proteins were defined as possible candidates for colistin resistance in mcr-negative S. Enteritidis of our collection. Conclusions: The colistin national surveillance in Salmonella spp. in humans, implemented with genomic-based surveillance, permitted to monitor colistin resistance, determining the prevalence of mcr determinants and the study of new candidate mechanisms for colistin resistance.

Bacterial Causes and their Antimicrobial Susceptibility Testing among Urinary Tract Infection Patients in Tobruk Area, Libya

Urinary tract infections are very common among people of all ages, but the disease is more prevalent in women, so proper clinical and laboratory diagnosis, and the right treatment are very important to avoid complications and antimicrobial resistance. This study aimed to determine the bacterial causes and antibiotic susceptibility patterns of UTI patients. Recorded results of 6065 urine sample cultures and their antimicrobial susceptibility tests from the Department of Microbiology in Tobruk Medical Center, Tobruk City, were obtained from September 2016 to December 2018. The data was analyzed and discussed in compare with other studies. The study showed that a UTI is more common in females (78.8%) compared with male patients (21.2%). Gram-negative bacteria accounted for the majority of urinary pathogens (90%), where E. coli alone was (58.4%), klebsiellae (17.4%), Proteus (10.7%), while Pseudomonas species was the least common (3.3%) of the total. While the Gram-positive bacteria S. aureus constituted 9.6% of the total. The study was found statistically significant (P=0.000). The most effective antibiotics against all uropathogens were Imipenem and Amikacin, and less effective antibiotics were Ampicillin and Amoxicillin-clavulanic acid. This study concluded that the most common cause of UTI in Tobruk was Escherichia coli and the most effective antibiotics appear to be Imipenem and Amikacin.

Antifungal Resistance in Clinical Isolates of Candida glabrata in Ibero-America

In different regions worldwide, there exists an intra-and inter-regional variability in the rates of resistance to antifungal agents in Candida glabrata, highlighting the importance of understanding the epidemiology and antifungal susceptibility profiles of C. glabrata in each region. However, in some regions, such as Ibero-America, limited data are available in this context. Therefore, in the present study, a systematic review was conducted to determine the antifungal resistance in C. glabrata in Ibero-America over the last five years. A literature search for articles published between January 2015 and December 2020 was conducted without language restrictions, using the PubMed, Embase, Cochrane Library, and LILACS databases. The search terms that were used were “Candida glabrata” AND “antifungal resistance” AND “Country”, and 22 publications were retrieved from different countries. The use of azoles (fluconazole, itraconazole, voriconazole, posaconazole, isavuconazole, ketoconazole, and miconazole) varied between 4.0% and 100%, and that of echinocandins (micafungin, caspofungin, and anidulafungin) between 1.1% and 10.0%. The limited information on this subject in the region of Ibero-America emphasizes the need to identify the pathogens at the species level and perform antifungal susceptibility tests that may lead to the appropriate use of these drugs and the optimal doses in order to avoid the development of antifungal resistance or multi-resistance.

Candida species cause vulvovaginitis and resistance to antifungals used for treatment

In this study were identified Candida species from vaginal secretion isolates, evaluated their in vitro antifungal susceptibilities, and correlated these features with antifungal agents prescribed for patients assisted in a primary care service. Species identification by Polymerase Chain Reaction showed that 36.5% of isolates were characterized as non-C. albicans species. In antifungal susceptibility tests most isolates were susceptible to ketoconazole, fluconazole, and itraconazole, although between 40% and 50% of isolates show resistance or dose-dependent susceptibility to miconazole and nystatin, respectively. Analysis of drugs prescribed to patients revealed that 34.2% of the isolates were considered resistant to agents used in treatment. Several Candida species can cause vulvovaginitis and exhibit different susceptibility profiles to antifungal drugs used in treatment. The identification of Candida species is relevant and useful to the epidemiological management of infections. The antifungal susceptibility test may also be useful for choosing most effective drug treatment for each patient.

Evaluating the Inappropriate Prescribing and Utilization of Caspofungin, a Four-Year Analysis at a Teaching Hospital in Saudi Arabia

The appropriate use of antimicrobial agents improves clinical outcomes and reduces antimicrobial resistance. Nevertheless, data on inappropriate prescription and negative outcomes are inconsistent. The objective of this study was to assess the prescription appropriateness of Caspofungin at a tertiary teaching hospital in Saudi Arabia and the impact on mortality at 30 days. A retrospective chart review was performed for patients who received Caspofungin from May 2015 to December 2019 to obtain prescription information and culture and susceptibility tests. The appropriateness of the dosage (ApD), initiation time (ApI), agent selection (ApS), and duration of therapy (ApDUR) was evaluated based on recommendations of the infectious diseases society of America. 355 eligible patients who received 3458 Caspofungin doses were identified. Their median age was 54 years (range 18–96). Overall, 270 (76.1%) patients received empirical prescriptions, of which 74.4% had the appropriate dose, and 56.3% had received it for more than five days, despite no proven Candida infection. This was not influenced by past medical history (p = 0.394). Only 39% of patients who received definitive prescriptions met all four study criteria for appropriate prescription. Therefore, antimicrobial stewardship programs can improve the appropriate utilization of antifungal therapies.

Staphylococcus aureus isolates from Eurasian Beavers (Castor fiber) carry a novel phage-borne bicomponent leukocidin related to the Panton-Valentine leukocidin

Staphylococcus aureus can be a harmless coloniser, but it can also cause severe infections in humans, livestock and wildlife. Regarding the latter, only few studies have been performed and knowledge on virulence factors is insufficient. The aim of the present study was to study S. aureus isolates from deceased wild beavers (Castor fiber). Seventeen isolates from eleven beavers, found in Germany and Austria, were investigated. Antimicrobial and biocide susceptibility tests were performed. Isolates were characterised using S. aureus-specific DNA microarrays, spa typing and whole-genome sequencing. From two isolates, prophages were induced by mitomycin C and studied by transmission electron microscopy. Four isolates belonged to clonal complex (CC) 8, CC12, and CC398. Twelve isolates belonged to CC1956 and one isolate was CC49. The CC49 and CC1956 isolates carried distinct lukF/S genes related to the Panton-Valentine leukocidin (PVL) from human isolates of S. aureus. These genes were located on related, but not identical, Siphovirus prophages. The beavers, from which those isolates originated, suffered from abscesses, purulent organ lesions and necrotising pneumonia, i.e., clinical manifestations resembling symptoms of severe PVL-associated disease in humans. It might thus be assumed that the “Beaver Leukocidin (BVL, lukF/S-BV)”-positive strains are beaver-specific pathogens, and further studies on their clinical role as well as on a possible transmissibility to other species, including humans, are warranted.

Whole-Genome Sequencing to Identify Missed Rifampicin and Isoniazid Resistance Among Tuberculosis Isolates—Chennai, India, 2013–2016

India has a high burden of drug-resistant tuberculosis (DR TB) and many cases go undetected by current drug susceptibility tests (DSTs). This study was conducted to identify rifampicin (RIF) and isoniazid (INH) resistance associated genetic mutations undetected by current clinical diagnostics amongst persons with DR TB in Chennai, India. Retrospectively stored 166 DR TB isolates during 2013–2016 were retrieved and cultured in Löwenstein-Jensen medium. Whole genome sequencing (WGS) and MGIT DST for RIF and INH were performed. Discordant genotypic and phenotypic sensitivity results were repeated for confirmation and the discrepant results considered final. Further, drug resistance-conferring mutations identified through WGS were analyzed for their presence as targets in current WHO-recommended molecular diagnostics. WGS detected additional mutations for rifampicin and isoniazid resistance than WHO-endorsed line probe assays. For RIF, WGS was able to identify an additional 10% (15/146) of rpoB mutant isolates associated with borderline rifampicin resistance compared to MGIT DST. WGS could detect additional DR TB cases than commercially available and WHO-endorsed molecular DST tests. WGS results reiterate the importance of the recent WHO revised critical concentrations of current MGIT DST to detect low-level resistance to rifampicin. WGS may help inform effective treatment selection for persons at risk of, or diagnosed with, DR TB.