Anaerobic resistance

Kulda J, Tachezy J, Cerkasovova A. 1993. In vitro induced anaerobic resistance to meteronidazole in Trichomonas vaginalis. J Eukary Microbiol 40 262-9. 

Anaerobic resistance was developed in both pathogenic species by prolonged cultivation of drug-susceptible strains or clones under increasing pressure of... 

Development of anaerobic resistance in both species was accompanied by a progressive decrease and eventual loss of PFOR and hydrogenase activities and ferredoxin levels. For development of anaerobic resistance in T. foetus, the decrease in PFOR activity was of crucial importance (Cerkasovova et al. 

Fig. 8 SDS-PAGE (a) and Western blot (b) analysis of the purified hydrogenosomal fractions isolated from the metronidazole-susceptible T. vaginalis strain TV 10-02 (P) and its metronidazole-resistant derivatives MR-3, MR-5, MR-30, MR-50, and MR-100 displaying the aerobic (3), early anaerobic (5), advanced anaerobic (30, 50), and fully developed anaerobic resistance (100) to metronidazole. Numbers in the designation of MR strains indicate the concentrations of metronidazole in ixg/ml at which the organisms multiply in culture. About 10 pg protein was loaded per line. PFOR pyruvate ferredoxin oxidoreduc-tase, a-STK a subunit of succinate thiokinase (hydrogenosomal enzyme not involved in metronidazole resistance used as control), Fdx ferredoxin. From Rasoloson et al. (2002) by courtesy of the Society of General Microbiology...

Of the two types of resistance identified, aerobic resistance is of clinical importance as most clinical isolates from treatment-refractory patients show resistance of this type. However, findings regarding the stepwise development of resistance, and continuity of resistance development from the aerobic to the anaerobic type, point to the possibility that I vaginalis strains at the early stage of anaerobic resistance could also appear in the field. In fact, some isolates reported from Upcroft s laboratory (Dunne al. 2004) and occasional isolates from surveys (e.g., Lossick et al. 1987) displaying high aerobic MLC... 

Kabickova H, Kulda J, Cerkasovova A, Nemcova H (1988) Metronidazole resistant Tritrichomonas foetus-, activities of hydrogenosomal enzymes in course of development of anaerobic resistance. Acta Univ Carol Biol 30 513-519 Kulda J (1999) Trichomonads, hydrogenosomes and drug resistance. Int J Parasitol 29 199-212... 

Small amounts of TAIC together with DAP have been used to cure unsaturated polyesters in glass-reinforced thermo sets (131). It has been used with polyfunctional methacrylate esters in anaerobic adhesives (132). TAIC and vinyl acetate are copolymerized in aqueous suspension, and vinyl alcohol copolymer gels are made from the products (133). Electron cure of poly(ethylene terephthalate) moldings containing TAIC improves heat resistance and transparency (134). 

Aerobic, Anaerobic, and Combined Systems. The vast majority of in situ bioremediations ate conducted under aerobic conditions because most organics can be degraded aerobically and more rapidly than under anaerobic conditions. Some synthetic chemicals are highly resistant to aerobic biodegradation, such as highly oxidized, chlorinated hydrocarbons and polynuclear aromatic hydrocarbons (PAHs). Examples of such compounds are tetrachloroethylene, TCE, benzo(a)pyrene [50-32-8] PCBs, and pesticides. 

Cefuroxime (35) is effective against community-acquired pneumonia in which ampicillin-resistant Haemophilus influence is the probable etiologic agent. Cefoxitin (23) is used to treat mixed aerobic—anaerobic infections including pelvic infections, intra-abdorninal infections, and nosocomial aspiration pneumonia. Cefonicid (31), because of its long half-life has been used in a once-a-day regimen to treat a variety of mild to moderate infections including community-acquired pneumonias, urinary tract infections, and infections of the skin and soft tissue (132,215). 

Light, sandy, well-drained soil of high electrical resistivity is low in corrosivity and coated steel or bare stainless steels can be employed. It is unlikely that the whole pipe run would be in the same type of soil. In heavier or damp soils, or where the quality of back filling cannot be guaranteed, there are two major corrosion risks. Steel, copper alloys and most stainless steels are susceptible to sulfide attack brought about by the action of sulfate-reducing bacteria in the soil. SRB are ubiquitous but thrive particularly well in the anaerobic conditions which persist in compacted soil, especially clay. The mechanism of corrosion where SRB are involved is described in Section... 

Soil resistivity The role of soil in the electrical circuitry of corrosion is now apparent. Thus the conductivity of the soil represents an important parameter. Soil resistivity has probably been more widely used than any other test procedure. Opinions of experts vary somewhat as to the actual values in terms of ohm centimetres which relate to metal-loss rates. The extended study of the US Bureau of Standards presents a mass of data with soil-resistivity values given. A weakness of the resistivity procedure is that it neither indicates variations in aeration and pH of the soil, nor microbial activity in terms of coating deterioration or corrosion under anaerobic conditions. Furthermore, as shown by Costanzo rainfall fluctuations markedly affect readings. Despite its short comings, however, this procedure represents a valuable survey method. Scott points out the value of multiple data and the statistical nature of the resistivity readings as related to corrosion rates (see also Chapter 10). 

Measurement of some of these parameters identifies the risk of a particular type of corrosion, for example pH measurements assess the risk of acid attack and redox potential measurements is used to assess the suitability of the soil for microbiological corrosion, a low redox potential indicates that the soil is anaerobic and favourable for the life cycle of anaerobic bacteria such as to sulphate-reducing bacteria. Other measurements are more general, resistivity measurements being the most widely quoted. However, as yet no single parameter has been identified which can confidently be expected to assess the corrosion risk of a given soil. It is therefore common practice to measure several parameters and make an assessment from the results. 

As other cheaper materials usually give satisfactory performance, nickel and nickel alloys are not normally required for applications involving resistance to corrosion underground. Data on their behaviour in these circumstances are therefore sparse in particular, whether micro-organisms responsible for the accelerated corrosion of ferrous and other metals in certain anaerobic soils have any influence on nickel and its alloys, is uncertain. 

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