README file
Data Set Title: “Hospitalized horses dataset: antimicrobial stewardship and AMR colonization”
Data Set Authors: 
Karen Mazzola1
Aliai Lanci1 (ORCID: https://orcid.org/0000-0002-9828-4317)
Silvia Piva1 (ORCID: https://orcid.org/0000-0003-0998-3368)
Jole Mariella1 (ORCID: https://orcid.org/0000-0003-4881-3898)
Raffaele Scarpellini1 (ORCID: https://orcid.org/0000-0002-9727-941X)
Francesca Freccero1 (ORCID: https://orcid.org/0000-0002-1645-2111)
Carolina Castagnetti1 (ORCID: https://orcid.org/0000-0001-5533-7637)

1Department of Veterinary Medical Sciences, University of Bologna, Ozzano dell’Emilia, Italia. 

Data set Contributors:
Viviana Schisa2 (ORCID: https://orcid.org/0009-0007-1479-0356)
Erica de Carolis2 (ORCID: https://orcid.org/0009-0005-0645-2977)
2 Department of Statistical Sciences, University of Bologna, Italy

Data Set Contact Person:
Aliai Lanci1: aliai.lanci2@unibo.it
1Department of Veterinary Medical Sciences, University of Bologna, Ozzano dell’Emilia, Italia.

Data Set License: This data set is distributed under a Creative Commons Attribution 4.0 
Publication Year: 2026 
A reference to the present dataset can be found in this manuscript which is currently being published: Clinical audit on antimicrobial stewardship effectiveness in reducing antimicrobial‐resistant bacterial colonisation in hospitalised horses, Equine Veterinary Journal, DOI: 10.1002/evj.70171

Data set Contents and Specifications
The data set consists of:
 •	1 tabular quantitative files saved in .csv format named “Dataset_Clinical_Audit_AMR.csv”. This file includes clinical and microbiological data from 328 hospitalized horses (foals and adults) across two audit cycles: A1 performed in 2022 and A2 performed in 2023 after antimicrobial stewardship implementation. File Specifications: the CSV file uses UTF-8 encoding, semicolons (;) as field separators, double quotes (") as string delimiters and commas (,) as decimal separators.”
 •	1 README file “Hospitalized_horses_Dataset:_antimicrobial_stewardship_and_AMR_colonization.rtf”
Data set Documentation
 •	Abstract
This dataset supports a clinical audit evaluating antimicrobial stewardship program (ASPs) in a Veterinary Teaching Hospital, focusing on antimicrobial-resistant bacteria (AMRb) colonization rates (CR) in horses under the One Health approach. Nasal and rectal swabs from 328 hospitalized horses (foals and adults) across two audit cycles:
 •	A1 (Jan-Jul 2022);
 •	A2 (Jan-Jul 2023): after ASP implementation about antimicrobial use (AMU) and biosecurity policy.
Swabs were collected at admission/birth (T0) and discharge/euthanasia/death (T1); tested for Methicillin-resistant Staphylococci (MRS), 3rd-generation Cephalosporin-resistant Gram-Negative Bacteria (3GCR-GNB), and Carbapenem-resistant Gram-Negative Bacteria (CR-GNB).

Content of the file:
This dataset includes clinical and microbiological data including signalment data (breed, age, gender, parity), medical history (diseases and antibiotic treatment before hospitalization), diagnosis, antibiotic treatment (type, dose and duration) and procedures (venous/urinary catheter, surgery, enemas, total parenteral nutrition and intranasal oxygen therapy) during hospitalization, ward assignments, hospitalization details (duration, seasonal periods). Furthermore, bacteriology results of swabs at T0 admission/birth and T1 discharge/death for MRS, 3GCR-GNB, CR-GNB and overall AMRb.

 •	Methodologies 
All 328 hospitalized horses were enrolled. Groups included foals (born at unit or ≤30 days old at admission) and adults (periparturient mares or other sick adults). Nasal/rectal swabs were collected at admission/birth (T0) and discharge/euthanasia/death (T1) using sterile AMIES swabs, refrigerated at 4°C, and processed within 48h. Collected clinical data included breed, age, history and clinical data during hospitalization.
Nasal swabs were cultured on Oxacillin Resistance Screening Agar Base (ORSAB, Oxoid, Wesel, Germany) for MRS. Rectal swabs were cultured on CHROMAGAR TM ESBL (Chromagar™, Paris, France) for 3GCR-GNB and on CHROMAGAR TM KPC (Chromagar™, Paris, France) for CR-GNB. Each streaked plate was incubated at 37+/- 1°C for 24 to 48 hours. Positive cultures were macroscopically evaluated, and every single colony typology was cloned into Tryptone Soy Agar media and kept at 37+/-1°C for 24 hours. Cloned strains were for phenotypic identification using the matrix-assisted laser desorption–ionization time-of-flight mass spectrometry method (MALDI-TOF MS; Biotyper, Bruker Daltonics, Billerica, MA), following manufacturer’s instructions (Bruker Daltonik, Bremen, Germany). Species identification was considered acceptable with a final ID score >2 (1.8 for Staphylococcus spp.). AMRb colonization rate was calculated by dividing the number of patients positive for at least one new AMRb species (MRS or 3GCR-GNB or CR-GNB) at T1 compared to T0 by the total number of subjects sampled.

List of variables
Year	A1= first audit cycle in 2022
A2= second audit cycle in 2023 after implementation	
Population A	Foals born at the unit	
Population B	Foal ≤30 days old hospitalized after birth.	
Population C	mares with normal or high-risk pregnancy hospitalized for attended parturition	
Population D	mares hospitalized after parturition with their foal for either one or both of the pair component disease	
Population E	adults other than periparturient mares.	
SIRS	Systemic Inflammatory Response Syndrome	
FPT	Failure of passive transfer of immunity (only for foals)	
Sample T0	Sample at admission/birth	
AMRb	antimicrobial-resistant bacteria	
MRS	Methicillin-resistant Staphylococci	
3GCR-GNB	3rd-generation Cephalosporin-resistant Gram-Negative Bacteria	
CR-GNB	Carbapenem-resistant Gram-Negative Bacteria	
CIAs	Critically Important Antibiotics: macrolides (rifampicin), fluoroquinolones (enrofloxacin, marbofloxacin), third- and fourth-generation cephalosporins (ceftiofur)	
EPU	Equine Perinatology Unit	
IMU	Internal Medicine Unit	
Sample T1	Sample at discharge/euthanasia/death