Historically, the rapid rise of human presence in Antarctica only started in the build-up to the International Geophysical Year in 1957/1958. Before that, there was relatively little human activity apart from a couple of whaling stations and Argentinian and UK research stations (Orcadas Base established on Laurie Island, South Orkneys in 1903 and several stations along the Antarctic Peninsula resulting from Operation Tabarin in 1943, respectively). The International Geophysical Year (IGY) of 1957-1958 sponsored the building of several research stations in Antarctica to support scientific exploration. This resulted in the core of the present-day network, which currently comprises 30 nations operating 76 permanent research stations [21, 22]. These represent a range of different sized operations, with some stations operating all year round, whilst others are only open for a few months in the Austral summer. Most stations generally have fewer than 60 beds. A handful has over 100 beds, including Marambio (170), Frei and Amundsen-Scott Pole (with 150 beds apiece), Rothera (136), Syowa (130) and Mario Zucchelli (124), but all are dwarfed by McMurdo, run by the USA near the Ross Sea with a capacity for 1200 personnel. Critically, the initial period of the station building and scientific expansion in Antarctica coincided with the development of modern antibiotics. Thus, even the earliest scientists had access to sulfonamides, as evidenced by medical stores lists from 1949 showing tablets and bottles of sulphathiazole (Additional file 1). They also potentially had access to penicillin in a period when waste regulation was non-existent.
Today, a wide range of antibiotics are available, which work against different aspects of cellular biosynthesis. These can be designated as natural, semi-synthetic or synthetic (Additional file 6), which aid in identifying whether humans are the potential drivers of resistance. Research investigating AMR in Antarctica dates back to the late 1970s/early 1980s with the limited screening (mainly for penicillin and tetracycline resistance) of environmentally isolated Antarctic bacteria and plasmids [24,25,26]. Since then, AMR screening on the continent has increased and revealed interesting results on the natural levels of AMR, mechanisms of resistance (albeit largely based on the identification of antibiotic resistance genes via sequencing, without associated functional data), evidence for anthropogenic influences on AMR levels and animals as vectors of AMR (Fig. 1, top panel; Additional file 3).
Penicillin Download J-rock
Resistance to β-lactams was more common than that to aminoglycosides in most studies carried out in the Antarctic, including King George Island (Additional file 5). Twelve studies found resistance to β-lactams across 29 sites, with phenotypic resistance to ampicillin, penicillin, cefazolin, cefuroxime, methicillin, oxacillin, amoxycillin, penicillin G, carbenicillin, ceftazidime and cefixime identified. Molecular resistance mechanisms to β-lactams, including genes such as blaCTX-M, blaTEM-117, blaTEM-157 and blaTEM-1, were also identified [51, 56, 63]. Ten of these studies found resistance to aminoglycosides across 16 sites. Phenotypic resistance was found to aminoglycosides such as streptomycin and kanamycin with the presence of genes such aadA, strA and strB [39, 63]. Additional antibiotic-resistant genes were identified that confer resistance to sulphonamides, e.g. sul1, sul2 and SulA [39, 47, 63]; quinolone, e.g. acra-04, oprJ, qacedelta and qach [59]; and efflux pumps, e.g. amrB and ceoB [39]. When the efficacy of some of these genes was assayed, it was interesting to note that the efflux pumps amrB and ceoB did not increase the tolerance of Antarctic bacteria to levels of clinical concern [39]. Therefore, it was suggested that even if these antibiotic-resistant genes are present, they may require selection pressure to generate significant risk in the future [39].
Since the discovery of penicillin in the 1920s, hundreds of antibiotic agents have been developed and applied for clinical use or animal treatment (Aarestrup and Wegener 1999). Vibrio species are usually susceptible to most veterinary and human antimicrobials (Oliver 2006). However, several studies have reported that antibiotic resistance has emerged and evolved in many bacterial genera including Vibrio spp. during the past few decades due to excessive use of antibiotics in human, agriculture, and aquaculture systems (Mazel and Davies 1999; Cabello 2006). As a result of the misuse of antibiotics to control infections during aquaculture production, V. parahaemolyticus exhibits multiple antibiotic resistance, which has increased concerns about public health and the economic threat of this bacterium (Lesmana et al. 2001; Ottaviani et al. 2013; Al-Othrubi et al. 2014; Shaw et al. 2014; Kim et al. 2016a, b; Kang et al. 2017). Elmahdi et al. (2016) reported that both environmental and clinical isolates of V. parahaemolyticus show similar antibiotic resistance profiles. Antibiotic resistance within a wide range of infectious agents is a growing public health threat of broad concern to multiple countries and sectors (WHO (World Health Organization) 2014).
Similarly, Kim et al. (2016a, b) reported that all V. parahaemolyticus strains (79 isolates), isolated in seawater samples from shellfish farms in Gomso Bay, Korea, were resistant to oxolinic acid, vancomycin, and penicillin, and 96.2% of all isolates also demonstrated resistance to ampicillin. Unexpectedly, all isolates were resistant to three or more classes of antibiotics.
PRE-PEN is indicated for the assessment of sensitization to penicillin (benzylpenicillin or penicillin G) in patients suspected to have clinical penicillin hypersensitivity. A negative skin test to PRE-PEN is associated with an incidence of immediate allergic reactions of less than 5% after the administration of therapeutic penicillin, whereas the incidence may be more than 50% in a history-positive patient with a positive skin test to PRE-PEN. These allergic reactions are predominantly dermatologic. Whether a negative skin test to PRE-PEN predicts a lower risk of anaphylaxis is not established. Similarly, when deciding the risk of proposed penicillin treatment, there are not enough data at present to permit relative weighing in individual cases of a history of clinical penicillin hypersensitivity as compared to positive skin tests to PRE-PEN and/or minor penicillin determinants.
PRE-PEN is contraindicated in those patients who have exhibited either a systemic or marked local reaction to its previous administration. Patients known to be extremely hypersensitive to penicillin should not be skin tested.
No reagent, test, or combination of tests will completely assure that a reaction to penicillin therapy will not occur. The value of the PRE-PEN skin test alone as a means of assessing the risk of administering therapeutic penicillin (when penicillin is the preferred drug of choice) in the following situations is not established:
In addition, the clinical value of PRE-PEN where exposure to penicillin is suspected as a cause of a current drug reaction or in patients who are undergoing routine allergy evaluation is not known. Likewise, the clinical value of PRE-PEN skin tests alone in determining the risk of administering semisynthetic penicillins (phenoxymethylpenicillin, ampicillin, carbenicillin, dicloxacillin, methicillin, nafcillin, oxacillin, amoxicillin), cephalosporin-derived antibiotics, and penem antibiotics is not known.
In addition to the results of the PRE-PEN skin test, the decision to administer or not administer penicillin should take into account individual patient factors. Healthcare professionals should keep in mind the following:
Pregnancy Category C: Animal reproduction studies have not been conducted with PRE-PEN. It is not known whether PRE-PEN can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. The hazards of skin testing in such patients should be weighed against the hazard of penicillin therapy without skin testing.
Fungi exist widely in different environments, such as soil, biological wastes and plants. Some of them have been utilized by humans for over 1000 years. In nature, fungi play a vital role in numerous degradation processes. In agriculture, many species of fungi are used for control of plant pests and diseases [1, 2]. In medicine, fungi are utilized to produce antibiotics for the treatment of diseases. For example, penicillin is a product of Penicillium chrysogenum and cephalosporin of Cephalosporium acremonium. Due to their good capacity in manufacturing valuable proteins and secondary metabolites, fungi are important economic contributors. With the explosion and exploration of fungal genomic sequence information, mycology is coming into a new era of functional studies [3].
Filamentous fungi, molds, grow well and rapidly on simple and inexpensive media and thus are preferred cell factories due to their outstanding capacity in expression and secretion of heterologous proteins with post-translational processing. They have also been used in the production of a wide variety of products, such as citric acid, kojic acid and other organic acids, secondary metabolites like penicillin, cephalosporin, as well as cellulase, amylase, glucanase, rennet, lipase, laccase and unsaturated fatty acids, soy sauce, fermented soya beans.
Aspergillus niger is a typical species used for producing glucoamylase and citric acid. In recent years, using fungi, such as A. niger, to produce cellulase to degrade inexpensive cellulosic materials into glucose with high efficiency has become one of research hotspots. Aspergillus oryzae, with a safe application history of over 1000 years, can be applied in producing protease, amylase, glucoamylase, cellulose, and phytase. As pointed out by Kubodera [6], A. oryzae, which has been one of the most important workhorses in Japanese fermentation industry, was used for the production of tempeh, one of the oldest fermented soy products in China [7]. A. oryzae can secrete a variety of enzymes, including amylase, protease and esterase, etc. Protein in beans can be hydrolyzed into soluble nitrogenous compounds by protease hydrolysis in the fermentation process. In addition, Kojic acid, which has an antibacterial effect on aerobic microbes, is an organic acid produced by A. oryzae. Because of its nontoxic property, Kojic acid has important applications such as being used as food additives, or in cosmetics, pharmaceuticals, etc. [8]. Aspergillus nidulans has been one of the most widely studied species in terms of genetics and biochemistry [9, 10]. It is often used as model organism in the identification of gene function and protein interaction studies [11, 12]. Penicillium is one of the most widely distributed fungi in nature. In medicine, penicillin also is the earliest clinical application of antibiotics. Additionally, Penicillium species have the capability of degrading lignocellulose. Monascus purpureus Went is mainly used traditionally for making wine, vinegar, food coloring, and meat preservation. In 1979, Brooklyn K (Monacolin K), an agent with activity to lower cholesterol levels [13], was isolated from Monascus. 2ff7e9595c
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