Essays academic service


Understanding the growth dynamics of e coli

Dozois, Editor Charles M. Address correspondence to Erick Denamur, rf. Day-to-day dynamics of commensal Escherichia coli in Zimbabwean cows evidence temporal fluctuations within a host-specific population structure. Appl Environ Microbiol 83: Received 2017 Mar 20; Accepted 2017 Apr 11.

The cows had not received antibiotic treatment during the previous 3 months. We performed viable E. We observed that E. No clone was shared by three or four cows. Clone richness and evenness were not different between cows. Within each host, the variability in the E. Dominant clones tended to persist longer than subdominant ones and were mainly from phylogenetic groups A and B1.

All cows harbored at least one Shiga toxin-producing E. Resistance to tetracycline, penicillins, trimethoprim, and sulfonamides was rare and observed in three clones that were shed at low levels in two cows. This study highlights the fact that the commensal E.

Over 25 days, we followed the total E.

Estimating bacterial growth dynamics

This study deals with the day-to-day dynamics of both quantitative and qualitative aspects of E. We show that the structure of these commensal populations was highly specific to the host, even though the cows ate and roamed together, and was highly dynamic between days.

Such data are of importance to understand the ecological forces that drive the dynamics of the emergence of E. Whether it is a pathogen 3 or not 4E. Although pathogenic strains have been extensively investigated and tracked to prevent health issues, key features of the gut commensal populations from which they emerge remain to be investigated.

As an example, Shiga toxin-producing E. STEC strains are primarily found in the gastrointestinal tract of ruminant animals, where they mainly live as commensals.

INTRODUCTION

Cattle feces are regarded as the main source of infection through the contamination of water or meat during the food chain process 67. However, the high degree of variability in the prevalence, duration, and level of shedding among cattle herds prevents us from defining a proper risk of human exposure to STEC isolates 89.

It has also been shown that gut commensal populations are implicated in the emergence and persistence of antibiotic-resistant pathogenic clones 10. When the gut microbiota is exposed to antibiotic molecules, resistant E. The rise in the incidence of carriage of these specific clones increases the resistance gene pool that may be transmitted to opportunistic pathogenic clones present in the gut. Moreover, knowledge about commensal E.

Understanding the growth dynamics of e coli

It would help us to predict which pathways of transmission between host populations that these pathogens are most likely to use 12— 14. The use of an indicator of pathogen transmission would be of great interest in some complex ecosystems where the high degree of ecological overlap between humans, domestic animals, and wild animals leads to a greater risk of interspecies pathogen spillover 17— 19.

Nonetheless, the population structure of commensal E.

  • When the gut microbiota is exposed to antibiotic molecules, resistant E;
  • Address correspondence to Erick Denamur, rf;
  • Similar patterns to those seen in vitro were also found for E.

Furthermore, most of the few studies that have aimed to obtain an understanding of the temporal dynamics of E. Combined with the already known intermittent nature of the shedding of STEC in cattle 926these studies highlight the fact that a precise description of the dynamic pattern at the clonal level requires shorter sampling intervals.

Individual-level sources of heterogeneity need to be untangled in upstream studies of the shedding and transmission patterns of clones of interest, such as STEC or antibiotic-resistant clones. The purpose of this study was to provide an in-depth baseline depiction of the temporal fluctuations in the gastrointestinal populations of E. We describe the daily variations, over a period of 25 days, in the total E.

All four cows shed E. The total mean E. The range of the E.

  1. Why do we care so much about the growth requirements of e coli let's review what we learned about e coli growth requirements understanding diseases.
  2. Summed across the population, the copy number of a DNA region will be higher the closer that region is to the replication origin and, conversely, lower the closer that region is to the terminus 20 , 21.
  3. However, the high degree of variability in the prevalence, duration, and level of shedding among cattle herds prevents us from defining a proper risk of human exposure to STEC isolates 8 , 9. During antibiotic recovery, obtained by washing the cultures after 2.
  4. To examine whether PTRs can be used to detect clinically relevant changes in culture conditions, we treated an in vitro culture of early log-phase nalidixic acid-resistant Citrobacter rodentium with the bacteriostatic antibiotic erythromycin.
  5. We describe the daily variations, over a period of 25 days, in the total E.

Within the cows, the range was narrower. Indeed, for each of the four cows, the E.