Early life supply of competitive exclusion products reduces colonization of extended spectrum beta-lactamase-producing Escherichia coli in broilers

Abstract

Broilers are an important reservoir of extended spectrum beta-lactamase and AmpC beta-lactamase (ESBL/pAmpC) -producing bacteria. In previous studies, a single supply of a competitive exclusion ( CE ) product before challenge with a high dose of ESBL/pAmpC-producing Escherichia coli led to reduced colonization, excretion, and transmission, but could not prevent colonization. The hypothesized mechanism is competition; therefore, in this study the effect of a prolonged supply of CE products on colonization, excretion, and transmission of ESBL-producing E. coli after challenge with a low dose at day 0 or day 5 was investigated. Day-old broilers (Ross 308) (n = 220) were housed in isolators. Two CE products, containing unselected fermented intestinal bacteria ( CEP ) or a selection of pre- and probiotics ( SYN ), were supplied in drinking water from day 0 to 14. At day 0 or 5, broilers were challenged with 0.5 mL with 10 1 or 10 2 cfu/mL E. coli encoding the beta-lactamase gene bla CTX-M-1 on an IncI plasmid ( CTX-M-1- E. coli ). Presence and concentration of CTX-M-1- E. coli were determined using cloacal swabs (days 0–14, 16, 19, and 21) and cecal content (day 21). Cox proportional hazard model and a mixed linear regression model were used to determine the effect of the intervention on colonization and excretion (log 10 cfu/g). When challenged on the day of hatch, no effect of CEP was observed. When challenged at day 5, both CEP and SYN led to a prevention of colonization with CTX-M-1- E. coli in some isolators. In the remaining isolators, we observed reduced time until colonization (hazard ratio between 3.71 × 10 −3 and 3.11), excretion (up to −1.60 log 10 cfu/g), and cecal content (up to −2.80 log 10 cfu/g), and a 1.5 to 3-fold reduction in transmission rate. Colonization after a low-dose challenge with ESBL-producing E. coli can be prevented by CE products. However, if at least 1 bird is colonized it spreads through the whole flock. Prolonged supply of CE products, provided shortly after hatch, may be applicable as an intervention to reduce the prevalence of ESBL/pAmpC-producing bacteria in the broiler production chain.

Competitive Exclusion Prevents Colonization and Compartmentalization Reduces Transmission of ESBL-Producing Escherichia coli in Broilers

“…In the control group, 93.5% of the broilers were colonized at the end of the experiment. These results are in line with earlier experiments within isolators, in which a continuous supply of CE product during the first 14 days was able to prevent colonization ( Dame-Korevaar et al, 2020 ). In the isolators in which at least one bird was colonized with ESBL-producing E. coli , application of CE products reduced the rate of colonization, decreased excretion (CFU/g) and reduced transmission, as previously shown in studies applying a single supply of CE ( Hofacre et al, 2002 ; Nuotio et al, 2013 ; Ceccarelli et al, 2017 ; Methner et al, 2019 ).…”

“…In chickens, microbiota in the first week of life contains Enterobacteriaceae ( Videnska et al, 2014 ; Ballou et al, 2016 ; Jurburg et al, 2019 ) suggesting that E. coli can easily colonize during the first week. Older bird might get less susceptible for colonization ( Dame-Korevaar et al, 2020 ), however in our study colonization with ESBL-producing E. coli still occurred at 21 days of life, maybe as a result of accumulation of excreted ESBL-producing E. coli in the environment. Once transmission between pens occurred, transmission within pens followed rapidly.…”

“…The unit of β within and β between in model 2 is 1/day 2 and is interpreted as the number of new colonized broilers per day, caused by each day that one positive broiler has been excreting CTX-M-1- E. coli ( Dekker et al, 2013 ; Dame-Korevaar et al, 2020 ).…”

“…Experimental studies showed that spatial separation between infectious and susceptible animals reduced the transmission rate of Campylobacter in broilers ( van Bunnik et al, 2012 ) and Streptococcus suis in pigs ( Dekker et al, 2013 ). Further, interventions aiming at preventing colonization by ESBL/pAmpC-producing E. coli in broilers have been described, such as acid-based feed additives ( Roth et al, 2017 ) or competitive exclusion (CE) products ( Nuotio et al, 2013 ; Ceccarelli et al, 2017 ; Methner et al, 2019 ; Dame-Korevaar et al, 2020 ). CE products are aimed at establishing a natural community of intestinal bacteria to protect broilers from colonization by invaders ( Nurmi et al, 1992 ).…”

“…Additionally, CE products resulted in a reduced intestinal and cecal excretion (CFU/g) after challenge with pathogenic E. coli ( Hofacre et al, 2002 ). A prolonged supply of CE product via the drinking water to broilers kept in isolators, from day of hatch until day 14 resulted in a delay and even prevention of colonization after challenge with a in the field realistic low dose of ESBL-producing E. coli ( Dame-Korevaar et al, 2020 ).…”