Prevalence and predictors of bacteremia in dairy calves with diarrhea

Abstract

Gastrointestinal disease is the most common cause of mortality in dairy calves. Septicemia is an important sequela of diarrhea, and the possibility of bacteremia is the primary justification for empirical antimicrobial therapy. Prior reports estimate that approximately onethird of diarrheic calves are bacteremic; however, those estimates may not be representative of routine cases in heifer calves on commercial dairy operations early in the course of disease. We hypothesized that the prevalence of bacteremia in calves with diarrhea and systemic signs of illness is less than prior estimates (~31%), and that clinical signs or hematological values would be associated with the presence or absence of bacteremia. Female calves less than 21 d of age with and without diarrhea were enrolled from 2 commercial dairy farms over a 10-wk period. Diarrheic calves were enrolled if they were newly diagnosed, had loose to watery stool, had either dehydration (assessed by skin tent and eye position) or depression (assessed by suckle reflex and standing ability), and had no prior antimicrobial treatments. Complete health assessments were conducted at 0, 7, and 14 d following enrollment. An aseptic jugular venous sample was collected and cultured using aerobic and anaerobic methods, and bacterial species were identified using mass spectrometry. Poisson regression models were used to identify associations with bacteremia and compute adjusted prevalence ratios. The prevalence of bacteremia in diarrheic and healthy calves was 9.26% (10/108, 95% confidence interval: 4.5-16%) and 14.8% (4/27, 95% confidence interval: 1.4-28.2%), respectively. Among calves with diarrhea, those with a fever (>39.7°C) or depression were 4.8 and 6.5 times more likely, respectively, to have bacteremia. Only 1 of 47 calves (2%) without signs of depression was bacteremic. The prevalence of bacteremia in diar-rheic calves with signs of systemic illness (depression or dehydration) was significantly lower than previous estimates, and bacteremia was rare among calves without observed depression. Antimicrobial therapy targeting bacteremia is not currently justified in routine cases of diarrhea in preweaning calves without signs of depression. These results suggest a substantial opportunity for more targeted antimicrobial therapy to improve antimicrobial stewardship.

Calf Diarrhea Is Associated With a Shift From Obligated to Facultative Anaerobes and Expansion of Lactate-Producing Bacteria

“…In horses with grain overload and cattle with ruminal acidosis the increase in facultative anaerobes, especially Enterobacteriaceae along with an acidic luminal environment is associated with cecal and ruminal mucosal damage and facilitate translocation of bacteria and their products into systemic circulation ( 30 – 34 ). This is of interest because bacteremia ( 35 – 37 ) and endotoxemia ( 38 ) has been reported in diarrheic calves with bacteremia occurring in 10 to 30% of diarrheic calves with E. coli and other facultative anaerobic Enterobacteriaceae bacteria (e.g., Salmonella, Enterobacter, Klebsiella ) being the most common bacteria isolated ( 35 – 37 ). These findings highlight the crucial role of gastrointestinal bacterial communities in local and systemic inflammatory responses observed in diarrheic calves.…”

Bayesian evaluation of sensitivity and specificity of blood culture media and hypoglycemia in sepsis‐suspected calves

“…To differentiate "likely contaminants" from "likely true pathogens," certain assumptions described in human medicine were applied; bacteria were considered true pathogens when they were members of the Enterobacterales or when they were isolated out of both aerobic BC flasks. 16,23,24 In addition, when the identified organism was a wellknown significant bovine pathogen in other pathologies (pneumonia, mastitis, peritonitis, …), it was also categorized as likely true pathogen, even if only isolated from 1 culture flask. In case the BACTEC FX system signaled positive, but no microbiological isolate could be detected (negative culture result), it was categorized as a contaminant.…”

“…13 Limited studies on BC from calves and minimal research on optimal sampling techniques force veterinarians to resort to human literature. 4,[14][15][16][17] In humans, BC volume proved crucial for more sensitive bacterial detection, even when taking more recent automated BC systems into account. [18][19][20][21] Furthermore, an inverse association between volume and contamination rate has been observed.…”

Effect of time of sample collection after onset of diarrhea on fecal microbiota composition of calves

“…The most common bacteria isolated from the blood culture of bacteremic diarrheic calves is E . coli and other bacteria from the family Enterobacteriaceae translocated from the lumen of the gastrointestinal tract 40‐43 . Thus, the enrichment of Escherichia/Shigella identified in the D 24‐48 groups might lead to the development of systemic clinical signs such as fever, anorexia, or severe depression leading farmers to administer antimicrobial treatment.…”

“…[37][38][39] The most common bacteria isolated from the blood culture of bacteremic diarrheic calves is E. coli and other bacteria from the family Enterobacteriaceae translocated from the lumen of the gastrointestinal tract. [40][41][42][43] Thus, the enrichment of Escherichia/Shigella identified in the D 24-48 groups might lead to the development of systemic clinical signs such as fever, anorexia, or severe depression leading farmers to administer antimicrobial treatment. This highlights the importance of developing treatment strategies such as fecal matter transplantation, probiotics, or prebiotics to manipulate the gastrointestinal microbiota soon after diarrhea onset to limit the negative effects of dysbiosis on calf health and reduce antimicrobial drugs use in diarrheic calves.…”