Table 3 Bacterial strain and inoculum
From: In vivo models of Escherichia coli infection in poultry
Bacterial strain information | Origin of the strain | Growth state | CFU (dose) | Volume (mL) | CFU/mL | CFU confirmation | Method of E. coli inoculation | Vehicle/broth | Positive control | Negative control | Time of euthanasia | References |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
EC317, O2:K1 | Isolated from a turkey with septicaemia | NA | Experiment 1: 1 × 104, 1 × 105 Experiment 2: 25, 250, 2500 | 100 µL | Dose dependent | NA | Intra-naval performed using a 27G needle and a 1 mL syringe | PBS | Not applicable | No | NA/reach of humane endpoint | [10] |
APEC O1 (O1:K1:H7) | Supplied by Prof Lisa Nolan, Iowa State University, USA | Stationary phase | Low dose: 2 × 105 High dose: 1.9 × 107 Repeat study: low, intermediate and high dose | 100 µL | Dose dependent | Serial dilutions | 100 µl PBS containing bacteria into the right caudal thoracic air sac | Luria Bertani broth, centrifuged and resuspended in PBS | Not applicable | In repeat study a sterile PBS control was included (n = 3) | 2 dpi and 7 dpi Repeat study: 14 h, 3 dpi, 7 dpi | [12] |
IMT5155, O2:K1:H5 | Outbreak isolate from the internal organs of a laying hen | Presumed exponential phase. Overnight culture diluted and grown at the day of inoculation, centrifuged and resuspended in PBS | 1 × 109 Depends on experiment | 0.5 mL | 109 | Serial dilutions | IT | Luria Bertani broth, centrifuged and resuspended in PBS | Not applicable | Intestinal E. coli isolate (IMT11327) and PBS | 24 and 48 h dpi | [11] |
APECO78 | Obtained from the ovary of a hen that died from egg yolk peritonitis | Grown until an optic density of 0.6–0.8 | 1 × 109 | 100 µL stated in pilot study | NA | NA | IU bacterial inoculation (1 mL syringe introduced through the vagina into to the uterus) and 2–3 mL egg yolk IP | Luria Bertani broth, centrifuged and washed in PBS and resuspended in egg yolk | Not applicable | Egg yolk IP and IU (Additionally, E. coli K12 during pilot studies) | 7 dpi | [13] |
O78 (nonhemolytic, aerobactin positive, serum resistant ad K1 negative) | Field isolate from broiler with cellulitis, pericarditis and airsacculitis | Grown for 12 h | Ranging from 1 × 105 to 1 × 109 (Bacteraemia induction 1 × 107) | 1 mL | Ranging from 1 × 105 to 1 × 109 | Serial dilutions | SC injection into the left caudal abdominal region | Grown in BHI, washed and resuspended in saline | Not applicable | Saline | Dose titration: 7 dpi Bacteraemia: 6 h and 1, 3, 5, 7 and 14 dpi | [14] |
E. coli O2 | Isolated from a chicken with septicaemia | Grown for 2.5 h | Approx. 1 × 103.7–4 | NA | NA | Serial dilutions | Inoculated into the left cranial thoracic air sac. At 8 dpi the birds were loaded onto a transportation vehicle, driven for 3 h and subsequently kept in the truck an additional 9 h. Temperature: 18–21 °C | Tryptose phosphate broth | Dexamethasone receiving groups | Yes, non-stressed and not receiving E. coli | 2 weeks dpi | [15] |
ST117 E44 (accession number LXWV00000000.1) | Clinical case of colibacillosis | Exponential phase (4 h growth at the final preparation step) | 1.9 × 107a,b | Not applicable | 1.9 × 107a,b | Serial dilutions | Inhalation of aerosolised inoculum while placed in a specialised chamber Aerosols were produced utilising Omron Ultrasonic Nebulizer NE-U17 (IT: buttoned cannula) | Lysogeny broth | Yes, IT | Sterile lysogeny broth (aerosolised and IT) | 2, 4, 5 and 7 dpi | [5] |
chicken/NL/Dev/SP01404Cou/05 | Hen with peritonitis from a flock with high mortality | 17 h growth prior to inoculation | 1 × 107.6–9.1 Aerosolsb: 1 × 105.1–5.7 and 1 × 106.2 | 1 mL (Aerosols: 100 mL diluted culture) | 1 × 107.6–9.1 | Bacterial counts | Numerous including IV (vena ulnaris, 23G needle), IP (23G needle), IT (knobbed, curved cannula), IVAG (knobbed, curved cannula), aerosol (1–4 exposures, spray head coupled to air compressor) and oral (knobbed, curved cannula) Some received 25 mL sterile egg yolk IP prior to E. coli inoculation (50 mL syringe, 18G needle) | Glucose broth (Aerosols: buffered peptone water) | Not applicable | IP or IT buffered peptone water | 2–4 weeks after inoculation | [16] |
EC-AR1, EC-CA1, EC-ALN1, EC-CA2, EC-ALN2, EC-AR2, EC-ALS1 | US cases of cellulitis in commercial broilers | Refers to [18] | Refers to [18] | Not applicable | 1 × 108 | Refers to [18] | Exp. 1: Scratches (2–3 cm and two on each bird paralleling the keel (to distinguish these from naturally occurring scratches), made with 18G needle) and placed on litter sprayed with 200 mL sterile saline or E. coli (108 CFU/mL) Exp. 2: Scratching as in exp. 1 and then placed on old litter from a previous cellulitis experiment | Refers to [19] | No/not applicable | Scratches and un-scratched birds on litter sprayed with 85% sterile saline | 7 dpi | [22] |
EC317 | Turkey with cellulitis, airsacculitis and pericarditis | 13 h of growth in BHI | Dose ranged from approx. 2 × 103.3 to 2 × 107c | 200 µL | Ranged between 1 × 104 and 1 × 108 | Plate count method | SC into breast | BHI | Not applicable | BHI | 21 dpi Earlier if severe clinical signs | [17] |
Cellulitis isolate | Cellulitis lesion in a broiler from Arkansas | Stationary (overnight culture) | Exp.1: 1 × 108 (main culture diluted 1:10) Exp.2: overnight culture | 1 mL | 1 × 109 | Serial dilutions | SC with a 1.5-inch, 20-Gauge needle either on dorsum, ventrum or the inguinal area (specified in the article) Swab onto area with plucked feather follicles (2–3 feathers plucked) Swab onto area with scratches (sterile scalpel used to induce scratches) | Exp.1: Sterile physiological saline Exp.2: Brain–heart infusion broth | Not applicable | Exp.1: 10 uninoculated | Exp.1: 7 dpi Exp.2: 6 h interval until 72 h thereafter 8 were killed weekly | [18] |
EC-AR1, EC-ALN1, ECALS1, EC-CA1 | Refers to [18] | Refers to [18] | Not applicable | Not applicable | 1 × 108 | Refers to [18] | Scratches with a length of 2–3 cm were induced with a 1.5-inch, 18-Gauge needle on the ventral surface paralleling the keel and subsequently placed on litter with 200 mL sterile saline/2.5 m2 or containing 108 CFU/mL | Sterile saline sprays on litter | No/not applicable | Scratched birds on un-inoculated litter Non-scratched birds | 7 dpi | [21] |
EC99 (O78), EC317 (O2) | Colisepticaemia in chicken and in turkey | 16 h growth | Not applicable/Aerosol | Not applicable (100 mL approx. was aerosolized) | 1 × 109 | Yes | Aerosols made with an Ultrasonic nebulizer. Administered in Horsfall unit (0.155 m3) or cone-shaped aerosol chamber (0.123 m3) depending on experiment | Grown in tryptic soy broth, washed 3× in PBS and resuspended in PBS | Not applicable | In one experiment, and PBS control was included | Depending on study 6 dpi (primarily) and 21 dpi | [20] |
E. coli strain C10821, ST117, O111:K_:H4 | Avian E. coli outbreak | Stationary (overnight culture) | 8.6 × 106 | 0.1 mL | 8.6 × 107 | Serial dilutions | Deposition directly into the oviduct during surgical procedure under general anaesthesia | Luria broth | Not applicable | Sterile broth | 48 h dpi | [19] |