Evaluation of Chromogenic Culture Media for Rapid Identification of Gram-Positive Bacteria Causing Subclinical Mastitis in Postpartum Period

Sep 8, 2026

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The study evaluates two chromogenic culture media for presumptive microbiological identification of mastitis-causing pathogens in postpartum milk samples, focusing on Gram-positive bacteria associated with subclinical mastitis. It addresses limitations of traditional approaches by comparing colony characteristics on chromogenic media with blood agar, including colony number, color, size, and hemolysis plus colony staining. A total of 536 samples are analyzed using a gold-standard framework with true-positive, true-negative, false-positive, and false-negative metrics.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages16

Reading Time40 min

AccessFree to download

Objective

Pathogens and target groups

Methods

Culture media evaluated

Sample size and comparison

Assessment criteria and gold standard

Evaluation of Chromogenic Culture Media for Rapid Identification of Gram-Positive Bacteria Causing Subclinical Mastitis in Postpartum Period Breno L. N. Garcia 1 , Brunna M. Granja 1 , Carlos E. Fidelis ¹ , Gustavo Freu¹ , Renata de F. Leite ¹ , Marcos V. dos Santos 1 1University of Sao Paulo, Pirassununga, São Paulo, Brazil Post-partum mastitis | NEB | • Poorly response to IMI
• Harm neutrophils and phagocytes migration and activity | | --- | --- | (AMARAL et al. , 2012) | Pre-existing and uncured IMI and new IMI = ↑ risk of CM postpartum | Dry Period | | --- | --- | (ARRUDA et al. , 2013) Laboratório de Pesquisa em Qualidade do Leite – [FMVZ/USP ](FMVZ/USP qualileite.org)[ qualileite.org](FMVZ/USP qualileite.org) On-farm Culture Chromogenic media Visual differentiation Sp Se Laboratório de Pesquisa em Qualidade do Leite – FMVZ/USP Differentiate species (FERREIRA et al. , 2018) [qualileite.org](qualileite.org) Objective Evaluate two chromogenic culture media for the presumptive microbiological identification of mastitis-causing pathogens in postpartum milk samples Laboratório de Pesquisa em Qualidade do Leite – FMVZ/USP Strep. uberis Strep. agalactiae Strep. dysgalactiae Staph. aureus Staph. saprophyticus Staph. epidermidis [qualileite.org](qualileite.org) Chromogenic media CHROMagar Mastitis GP base (GP) CHROMagar Staphylococcus (S) Gram-positive bacteria Staphylococcus Turquoise blue Strep. agalactiae Strep. dysgalactiae Turquoise blue Staph. saprophyticus Pink Staph. aureus Pink Staph. aureus Compared with blood agar (BA) Metallic blue Strep. uberis Enterococcus spp. Colourless/Pinkish Staph. epidermidis Laboratório de Pesquisa em Qualidade do Leite – [FMVZ/USP ](FMVZ/USP qualileite.org)[ qualileite.org](FMVZ/USP qualileite.org) 536 samples Laboratório de Pesquisa em Qualidade do Leite – FMVZ/USP Analysis BA • Number of colonies • Color • Size • Hemolysis Colony staining [qualileite.org](qualileite.org) Laboratório de Pesquisa em Qualidade do Leite – FMVZ/USP Gold standard • TP: true-positive • TN: true-negative • FP: false-positive • FN: false-negative [qualileite.org](qualileite.org)

FAQs

What is the main objective of the study?

To evaluate two chromogenic culture media for presumptive identification of mastitis-causing pathogens in postpartum milk samples.

Which types of media are compared in the evaluation?

The study compares chromogenic media (CHROMagar Mastitis GP base and CHROMagar Staphylococcus) with blood agar (BA).

What criteria are used to assess bacterial growth and identification?

Assessment includes colony number, color, size, and hemolysis, supported by colony staining and a gold-standard TP/TN/FP/FN evaluation.

Sep 8, 2026

Upload by Noah