Inactivation kinetics of some microorganisms subjected to a variety of stresses

Cox, C. S.

doi:10.1128/aem.31.6.836-846.1976

Cited by 19 publications

(4 citation statements)

References 32 publications

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“…'Shouldering' refers to an increase of UV 254 dose with no corresponding increase in microbial inactivation, whereas 'tailing' is a decrease in UV 254 dose with no corresponding decrease in microbial inactivation (Hiatt, 1964). In contrast to the one-stage inactivation model, the two-stage model proposes that exposure of microbial populations to an inactivating agent may reveal two subpopulations: one subpopulation (f) more susceptible to inactivation and a second subpopulation (1-f) more resistant (Hiatt, 1964;Cox, 1976;Kowalski et al, 2002).…”

Section: Chick's Lawmentioning

confidence: 99%

“…‘Shouldering’ refers to an increase of UV 254 dose with no corresponding increase in microbial inactivation, whereas ‘tailing’ is a decrease in UV 254 dose with no corresponding decrease in microbial inactivation (Hiatt, 1964). In contrast to the one-stage inactivation model, the two-stage model proposes that exposure of microbial populations to an inactivating agent may reveal two subpopulations: one subpopulation ( f ) more susceptible to inactivation and a second subpopulation (1– f ) more resistant (Hiatt, 1964; Cox, 1976; Kowalski et al , 2002). where N t is the quantity of virus in the test sample after treatment with Dose t , N 0 is the quantity of virus in the unexposed control sample, f is the resistant fraction of the total initial virus population with inactivation rate K 2 , (1– f ) is the susceptible virus population fraction with inactivation rate K 1 , k 1 is the inactivation rate of the inactivation curve for the ‘fast decay population’, k 2 is the inactivation rate of the inactivation curve for the ‘resistant population’ and Dose t is the UV 254 intensity×time.…”

Section: Principles Of Inactivation By Uv Radiationmentioning

confidence: 99%

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Ultraviolet irradiation and the mechanisms underlying its inactivation of infectious agents

Cutler

Zimmerman

2011

Anim. Health. Res. Rev.

186

128

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We review the principles of ultraviolet (UV) irradiation, the inactivation of infectious agents by UV, and current applications for the control of microorganisms. In particular, wavelengths between 200 and 280 nm (germicidal UV) affect the double-bond stability of adjacent carbon atoms in molecules including pyrimidines, purines and flavin. Thus, UV inactivation of microorganisms results from the formation of dimers in RNA (uracil and cytosine) and DNA (thymine and cytosine). The classic application of UV irradiation is the inactivation of microorganisms in biological safety cabinets. In the food-processing industry, germicidal UV irradiation has shown potential for the surface disinfection of fresh-cut fruit and vegetables. UV treatment of water (potable and wastewater) is increasingly common because the process is effective against a wide range of microorganisms, overdose is not possible, chemical residues or by-products are avoided, and water quality is unaffected. UV has been used to reduce the concentration of airborne microorganisms in limited studies, but the technology will require further development if it is to gain wider application. For bioaerosols, the primary technical challenge is delivery of sufficient UV irradiation to large volumes of air, but the absence of UV inactivation constants for airborne pathogens under a range of environmental conditions (temperature, relative humidity) further compounds the problem.

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Section: Chick's Lawmentioning

confidence: 99%

Section: Principles Of Inactivation By Uv Radiationmentioning

confidence: 99%

Ultraviolet irradiation and the mechanisms underlying its inactivation of infectious agents

Cutler

Zimmerman

2011

Anim. Health. Res. Rev.

186

128

View full text Add to dashboard Cite

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“…Penetration into the alveolar region, in particular, is highly variable, and it is unclear whether the liquid delivered with the pathogenic agent might alter lung physiology, further complicating matters. Studies using aerosols of F. tularensis were employed extensively in the 1950s, 1960s, and 1970s (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). There has been renewed interest in F. tularensis since letters containing anthrax were sent in 2001.…”

mentioning

confidence: 99%

Development, Characterization, and Standardization of a Nose-Only Inhalation Exposure System for Exposure of Rabbits to Small-Particle Aerosols Containing Francisella tularensis

et al. 2019

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Inhalation of Francisella tularensis causes pneumonic tularemia in humans, a severe disease with a 30 to 60% mortality rate. The reproducible delivery of aerosolized virulent bacteria in relevant animal models is essential for evaluating medical countermeasures. Here we developed optimized protocols for infecting New Zealand White (NZW) rabbits with aerosols containing F. tularensis. We evaluated the relative humidity, aerosol exposure technique, and bacterial culture conditions to optimize the spray factor (SF), a central metric of aerosolization. This optimization reduced both inter-and intraday variability and was applicable to multiple isolates of F. tularensis. Further improvements in the accuracy and precision of the inhaled pathogen dose were achieved through enhanced correlation of the bacterial culture optical density and the number of CFU. Plethysmograph data collected during exposures found that respiratory function varied considerably between rabbits, was not a function of weight, and did not improve with acclimation to the system. Live vaccine strain (LVS)-vaccinated rabbits were challenged via aerosol with human-virulent F. tularensis SCHU S4 that had been cultivated in either Mueller-Hinton broth (MHB) or brain heart infusion (BHI) broth. LVS-vaccinated animals challenged with SCHU S4 that had been cultivated in MHB experienced short febrile periods (median, 3.2 days), limited weight loss (Ͻ5%), and longer median survival times (ϳ18 days) that were significantly different from those for unvaccinated controls. In contrast, LVS-vaccinated rabbits challenged with SCHU S4 that had been cultivated in BHI experienced longer febrile periods (median, 5.5 days) and greater weight loss (Ͼ10%) than the unvaccinated controls and median survival times that were not significantly different from those for the unvaccinated controls. These studies highlight the importance of careful characterization and optimization of protocols for aerosol challenge with pathogenic agents.

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“…This liquid/gas jet is further impacted against the inside of the Collison nebulizer jar to remove the larger fraction of the droplets from the aerosol (May 1973). The susceptibility of bacilli to nebulization has been shown to affect viability in the suspended aerosol (Cox 1976; Griffiths et al. 1996; Heidelberg et al.…”

Section: Discussionmentioning

confidence: 99%

Survival of Mycobacterium tuberculosis during experimental aerosolization and implications for aerosol challenge models

Clark¹,

Hall²,

Kelly³

et al. 2011

Journal of Applied Microbiology

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Aims: We undertook a series of experiments to investigate factors that contribute to variation in Mycobacterium tuberculosis viability and infectivity, during experimental aerosolization, with an aim to optimize a strategy to enable a more reproducible delivered dose within animal models of tuberculosis. Methods and results: The viability and infectivity of the challenge suspension was determined in relation to aerosolization time, concentration, method of preparation and M. tuberculosis strain. Challenge stocks generated from frozen aliquots of M. tuberculosis were shown to undergo a 1 log10 CFU ml−1 decrease in viability during the first 10 min of aerosolization. This correlated with a decrease in surface lung lesions developing in guinea pigs challenged during this time. The phenomenon of decreased viability in vitro was not observed when using freshly grown, nonfrozen cells of M. tuberculosis. The viability of aerosolized bacilli at the point of inhalation relative to the point of aerosolization always remained constant. Conclusion: Based on these findings, we have developed an improved strategy by which to reproducibly deliver aerosol infection doses to individually challenged animals and separately challenged groups of animals. Significance and Impact of the Study: Study of the aerobiological characteristics of micro‐organisms is a critical step in the validation of methodology for aerosol infection animal models, particularly where large numbers of animals and nonhuman primates are used.

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Inactivation kinetics of some microorganisms subjected to a variety of stresses

Cited by 19 publications

References 32 publications

Ultraviolet irradiation and the mechanisms underlying its inactivation of infectious agents

Ultraviolet irradiation and the mechanisms underlying its inactivation of infectious agents

Development, Characterization, and Standardization of a Nose-Only Inhalation Exposure System for Exposure of Rabbits to Small-Particle Aerosols Containing Francisella tularensis

Survival of Mycobacterium tuberculosis during experimental aerosolization and implications for aerosol challenge models

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