Subclinical Mastitis Related to <i>Streptococcus canis</i> Infection in Dairy Cattle

In the present study, we isolated <i>S. canis</i> from milk samples in a dairy farm with suspicions of subclinical mastitis. Milk samples testing positive on California Mastitis Test (CMT) were collected from different cows for bacteriological and genomic analyses to identify the causati...

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Main Authors: Alessio Sposato, Laura Del Sambro, Stefano Castellana, Elisabetta Catalano, Michela Galgano, Antonella Castellana, Annamaria Caffò, Viviana Manzulli, Marta Caruso, Leonardo Marino, Angelica Milano, Luciana Addante
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Language:English
Published: MDPI AG 2025-03-01
Series:Veterinary Sciences
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Online Access:https://www.mdpi.com/2306-7381/12/3/286
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author Alessio Sposato
Laura Del Sambro
Stefano Castellana
Elisabetta Catalano
Michela Galgano
Antonella Castellana
Annamaria Caffò
Viviana Manzulli
Marta Caruso
Leonardo Marino
Angelica Milano
Luciana Addante
author_facet Alessio Sposato
Laura Del Sambro
Stefano Castellana
Elisabetta Catalano
Michela Galgano
Antonella Castellana
Annamaria Caffò
Viviana Manzulli
Marta Caruso
Leonardo Marino
Angelica Milano
Luciana Addante
author_sort Alessio Sposato
collection DOAJ
description In the present study, we isolated <i>S. canis</i> from milk samples in a dairy farm with suspicions of subclinical mastitis. Milk samples testing positive on California Mastitis Test (CMT) were collected from different cows for bacteriological and genomic analyses to identify the causative pathogen, and somatic cell counts (SCC) were determined. A multiplex qPCR assay was conducted to detect 15 potential pathogens, and all samples showed negative results. Conventional bacteriology procedures were performed; DNA of the bacterial strains was extracted, sequenced, and submitted to bioinformatic analysis. Three CMT positive milk samples showed SCC > 200 × 10<sup>3</sup> cell/mL. However, these same three samples were positive for bacteria phenotypically identified as Streptococci, and the strains were confirmed as <i>S. canis</i> using MS MALDI-TOF methodology. In susceptibility testing, resistance against tetracycline was detected, revealing a potential chronic infection in one cow, while the presence of the same bacteria was observed in two other cows. Genomic DNA from four <i>S. canis</i> isolates, obtained in the first and second sampling, was sequenced. Genetic relationships revealed a unique sequence type (ST24). The gene (<i>tetM</i>) related with resistance to TE was highlighted. Although the association between <i>S. canis</i> and mastitis is not routinely detected, early diagnosis of bacterial infections and the study of the antimicrobial profile are crucial for effective therapy. Pets could act as a potential reservoir, so improving hygienic conditions is needed to prevent new infections.
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spelling doaj-art-d7a198f21ff24048abd3e2eb4c45efac2025-08-20T03:43:51ZengMDPI AGVeterinary Sciences2306-73812025-03-0112328610.3390/vetsci12030286Subclinical Mastitis Related to <i>Streptococcus canis</i> Infection in Dairy CattleAlessio Sposato0Laura Del Sambro1Stefano Castellana2Elisabetta Catalano3Michela Galgano4Antonella Castellana5Annamaria Caffò6Viviana Manzulli7Marta Caruso8Leonardo Marino9Angelica Milano10Luciana Addante11Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Via Carlo Forlanini 2, 27100 Pavia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIstituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, ItalyIn the present study, we isolated <i>S. canis</i> from milk samples in a dairy farm with suspicions of subclinical mastitis. Milk samples testing positive on California Mastitis Test (CMT) were collected from different cows for bacteriological and genomic analyses to identify the causative pathogen, and somatic cell counts (SCC) were determined. A multiplex qPCR assay was conducted to detect 15 potential pathogens, and all samples showed negative results. Conventional bacteriology procedures were performed; DNA of the bacterial strains was extracted, sequenced, and submitted to bioinformatic analysis. Three CMT positive milk samples showed SCC > 200 × 10<sup>3</sup> cell/mL. However, these same three samples were positive for bacteria phenotypically identified as Streptococci, and the strains were confirmed as <i>S. canis</i> using MS MALDI-TOF methodology. In susceptibility testing, resistance against tetracycline was detected, revealing a potential chronic infection in one cow, while the presence of the same bacteria was observed in two other cows. Genomic DNA from four <i>S. canis</i> isolates, obtained in the first and second sampling, was sequenced. Genetic relationships revealed a unique sequence type (ST24). The gene (<i>tetM</i>) related with resistance to TE was highlighted. Although the association between <i>S. canis</i> and mastitis is not routinely detected, early diagnosis of bacterial infections and the study of the antimicrobial profile are crucial for effective therapy. Pets could act as a potential reservoir, so improving hygienic conditions is needed to prevent new infections.https://www.mdpi.com/2306-7381/12/3/286<i>Streptococcus canis</i>bacteriabovine mastitiscattlewhole genome sequencingintramammary infection
spellingShingle Alessio Sposato
Laura Del Sambro
Stefano Castellana
Elisabetta Catalano
Michela Galgano
Antonella Castellana
Annamaria Caffò
Viviana Manzulli
Marta Caruso
Leonardo Marino
Angelica Milano
Luciana Addante
Subclinical Mastitis Related to <i>Streptococcus canis</i> Infection in Dairy Cattle
Veterinary Sciences
<i>Streptococcus canis</i>
bacteria
bovine mastitis
cattle
whole genome sequencing
intramammary infection
title Subclinical Mastitis Related to <i>Streptococcus canis</i> Infection in Dairy Cattle
title_full Subclinical Mastitis Related to <i>Streptococcus canis</i> Infection in Dairy Cattle
title_fullStr Subclinical Mastitis Related to <i>Streptococcus canis</i> Infection in Dairy Cattle
title_full_unstemmed Subclinical Mastitis Related to <i>Streptococcus canis</i> Infection in Dairy Cattle
title_short Subclinical Mastitis Related to <i>Streptococcus canis</i> Infection in Dairy Cattle
title_sort subclinical mastitis related to i streptococcus canis i infection in dairy cattle
topic <i>Streptococcus canis</i>
bacteria
bovine mastitis
cattle
whole genome sequencing
intramammary infection
url https://www.mdpi.com/2306-7381/12/3/286
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