Viability and Estimation of Shelf-Life of Bacterial Populations1

DeArmon, Ira A.; Orlando, Michael D.; Rosenwald, Albert J.; Klein, Frederick; Fernelius, Albert L.; Lincoln, Ralph E.; Middaugh, Paul R.

doi:10.1128/aem.10.5.422-427.1962

Cited by 9 publications

(4 citation statements)

References 8 publications

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“…Naturally contaminated mud samples originating from Cattail Creek (Montana, USA) were stored under the same conditions but gave varying results, with persistence lasting throughout a 4- to 10-week period ( 12 ). Dearmon et al ( 48 ) investigated survival in F. tularensis liquid cultures after storage at constant temperatures (37, 26, 15, 3, and 0°C) for 1 to 111 days and found that long-term survival through the entire time period occurred only at the lowest temperatures (3°C and 0°C), with the highest proportions of culturable cells at 3°C. However, it should be noted that both studies ( 12 , 48 ) were performed before the division of F. tularensis into subspecies came into practice, and it is not clear if F. tularensis subsp.…”

Section: Discussionmentioning

confidence: 99%

Long-Term Survival of Virulent Tularemia Pathogens outside a Host in Conditions That Mimic Natural Aquatic Environments

Golovliov

Bäckman

Granberg

et al. 2021

Appl Environ Microbiol

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Francisella tularensis, causative agent of the zoonotic disease tularemia, can cause seasonal outbreaks of acute febrile illness in humans with disease peaks in late summer to autumn. Interestingly, its mechanisms for environmental persistence between outbreaks are poorly understood. One hypothesis is that F. tularensis forms biofilm in aquatic environments. We utilized two fully virulent wild type strains: FSC200 (F. tularensis subsp. holarctica) and Schu S4 (F. tularensis subsp. tularensis); and three control strains: the attenuated Live Vaccine Strain (LVS; F. tularensis subsp. holarctica), a Schu S4 ΔwbtI mutant that is documented to form biofilms, and the low virulence U112 strain of the closely-related species Francisella novicida. Strains were incubated in saline solution (0.9% NaCl) microcosms for 24 weeks at both 4°C and 20°C whereupon viability and biofilm formation were measured. These temperatures were selected to approximate winter and summer temperatures of fresh water in Scandinavia, respectively. U112 and Schu S4 ΔwbtI formed biofilms, but F. tularensis strains FSC200, Schu S4, and LVS did not. All strains exhibited prolonged viability at 4°C compared to 20°C. U112 and FSC200 displayed remarkable long-term persistence at 4°C, with only a one- and two-fold log reduction, respectively, of viable cells after 24 weeks. Schu S4 exhibited lower survival, yielding no viable cells by week 20. At 24 weeks, cells from FSC200, but not from Schu S4, were still fully virulent in mice. Taken together, these results demonstrate biofilm-independent, long-term survival of pathogenic F. tularensis subsp. holarctica in conditions that mimic over-winter survival in aquatic environments. Importance Tularemia, a disease caused by the environmental bacterium, Francisella tularensis, is characterized by acute febrile illness. F. tularensis is highly infectious: as few as 10 organisms can cause human disease. Tularemia is not known to be spread from person to person. Rather, all human infections are independently acquired from the environment via the bite of blood-feeding arthropods, ingestion of infected food or water, or inhalation of aerosolized bacteria. Despite the environmental origins of human disease events, the ecological factors governing the long-term persistence of F. tularensis in nature between seasonal human outbreaks are poorly understood. The significance of our research is in identifying conditions that promote long-term survival of fully virulent F. tularensis outside a mammalian host or insect vector. These conditions are similar to those found in natural aquatic environments in winter and provide important new insights on how F. tularensis may persist long-term in the environment.

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Section: Discussionmentioning

confidence: 99%

Long-Term Survival of Virulent Tularemia Pathogens outside a Host in Conditions That Mimic Natural Aquatic Environments

Golovliov

Bäckman

Granberg

et al. 2021

Appl Environ Microbiol

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“…The death rate of freeze dried bacteria is often assumed to be exponential but the published evidence for this is equivocal. I n fact one of the few statistical analyses of death rates (de Armon et al, 1962) suggested that for Pmteurella tularensis a probit model is preferable to an exponential model, and curves obtained by Heokley (1961) and Scott (1958) appear to indicate that the decay rate for the bacteria they were working with may decrease with time. The estimates of k used to calculate the h values in Table 2 assume that these rates are exponential but the variations in most of the data were such that it might have been equally valid to assume that they should follow probit curves or curves with small rates of decrease of k. In practice this may not be important because predictions of useful storage life for these organisms assuming an exponential decay would not be markedly different from predictions calculated by fitting the data to either of the other models.…”

Section: Discussionmentioning

confidence: 99%

The Preservation of Plant Pathogenic Bacteria

Lelliott¹

1965

J Appl Microbiol

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Some 160 cultures wcre preserved by freeze drying, under mineral oil and in soil. After storage for 5 years all freeze dried cultures were viable; most cultures of xanthomonads were viable under oil and in soil; pseudomonads snrvived well in soil but only moderately well under oil; soft-rotting Eruinia spp. survived poorly but storage under oil was better than in soil; other Erwinia spp. and most Corynebacterium spp.survived well in soil and under oil. The mean half lives in years (h) calculated for freeze dried cultures of groups of closely related bacteria were : Erwinia 'chrysanthemi group', 0.40; Erwinia 'carotovora group', 0.51 : Pseudomonas 'syringae group', 0.50; Xanthoinonas spp., 0 4 4 years. Estimated half lives for Corynebacterium spp. ranged from 1.8 to 6.5 years. There was no evidence that bacteria which had been in culture for more than 3 years before being freeze dried had a longer storage life than those freeze dried within 3 years of isolation. Cultures of the Pseudomonas 'syringae group' had a longer storage life when freeze dried by Greaves' method (h=0.73) than whcn freeze dried by Annear's method (h = 0.50). There appeared to be no general correlation between half life in storage and either the proportion of cells surviving the freeze drying process or the viable cell count immediately after freeze drying. Most of the variation in the results could be attributed to variation in viable cell count between different ampoules of the same batch of a culture.

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“…the ability to maintain viability over time) of vegetative bacterial agents in the environment is known to be less than that of bacterial spores (Stuart and Wilkening 2005;Sinclair et al 2008). Nonetheless, it has been demonstrated that viral and vegetative agents can remain viable in the environment for months to years (Dearmon et al 1962;Wolff and Croon 1968). Previous work by US EPA has shown that Br.…”

Section: Introductionmentioning

confidence: 99%

“…2008). Nonetheless, it has been demonstrated that viral and vegetative agents can remain viable in the environment for months to years (Dearmon et al. 1962; Wolff and Croon 1968).…”

Section: Introductionmentioning

confidence: 99%

The effects of environmental conditions on persistence and inactivation of Brucella suis on building material surfaces

Calfee

Wendling

2012

Letters in Applied Microbiology

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Aims: The purpose of this study was to evaluate the effects of environmental conditions and material type on persistence and inactivation of Brucella suis. Methods and Results: Brucella suis (approx. 1 × 108 CFU) was spiked onto surfaces (glass, aluminium and wood) by liquid inoculation. Persistence was evaluated over 56 days at 22 ± 2°C, 40 ± 15% r.h. and 5 ± 3°C, 30 ± 15% r.h. In addition, three readily available decontaminants (pH‐adjusted bleach, 70% ethanol and 1% citric acid) were evaluated for their effectiveness at inactivating Br. suis on these materials. Decontaminations were conducted following 0 and 28 days exposure to the two conditions. Results indicated that Br. suis can persist on environmental surfaces for at least 56 days. Persistence was highest at low temperature. Decontamination was most challenging on wood with all three decontaminants. Conclusions: Following a Br. suis contamination incident, passive decontamination (through attenuation) may not be feasible, as this organism can persist for months. In addition, the results suggest that some sporicidal decontaminants may be ineffective on materials such as wood, even for vegetative biological agents such as Br. suis. Significance and Impact of Study: This study aids incident commanders and remediation experts to make informed decisions regarding decontamination after a biological contamination incident.

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Viability and Estimation of Shelf-Life of Bacterial Populations1

Cited by 9 publications

References 8 publications

Long-Term Survival of Virulent Tularemia Pathogens outside a Host in Conditions That Mimic Natural Aquatic Environments

Long-Term Survival of Virulent Tularemia Pathogens outside a Host in Conditions That Mimic Natural Aquatic Environments

The Preservation of Plant Pathogenic Bacteria

The effects of environmental conditions on persistence and inactivation of Brucella suis on building material surfaces

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