title: Relationship between milk cathelicidin abundance and microbiologic culture in clinical mastitis.
abstract: The availability of reliable tools to enable the sensitive and specific detection of mastitis in dairy cows can assist in developing control strategies and promote the more rational use of antibiotics. We have developed a milk cathelicidin ELISA that shows high sensitivity and specificity for dairy cow mastitis, based on latent class analysis. In this study, we investigated the effect of microbial agents on cathelicidin abundance in the milk of cows with clinical mastitis. We subjected 535 quarter milk samples (435 from quarters showing signs of clinical mastitis and 100 from healthy quarters as a control) to milk cathelicidin ELISA, somatic cell count (SCC), and microbiologic culture. Of the 435 clinical mastitis samples, 431 (99.08%) were positive for cathelicidin, 424 (97.47%) had SCC >200,000 cells/mL, and 376 (86.44%) were culture-positive. Of the 59 culture-negative samples, 58 (98.30%) were positive for cathelicidin and 55 (93.22%) had SCC >200,000 cells/mL. The abundance of cathelicidin and the extent of SCC increase depended on the causative agent: Streptococcus agalactiae and coagulase-negative staphylococci showed the highest and lowest changes, respectively. We also observed differences in behavior between the 2 markers depending on the pathogen: Streptococcus agalactiae induced the highest cathelicidin abundance, and Serratia spp. induced the highest SCC. Nevertheless, the different ability of microorganisms to induce cathelicidin release in milk did not compromise its value as a mastitis marker, given its higher sensitivity compared to SCC or microbiologic culture. All 100 negative control samples (collected from healthy quarters with SCC <100,000 cells/mL and culture-negative) were also negative for cathelicidin, corresponding to 100% specificity in the evaluated sample cohort. This study confirmed the value of the milk cathelicidin ELISA for detecting bovine mastitis, and highlighted the influence of mastitis-causing microorganisms on cathelicidin abundance. This influence did not compromise diagnostic performance; instead, it may have better reflected disease severity and evolution than SCC.
authors.affiliation: Porto Conte Ricerche, SP 55 Porto Conte/Capo Caccia, Km 8.400, Loc. Tramariglio, 07041 Alghero, Italy. Electronic address: addis@portocontericerche.it.
authors.forename: M F
authors.initials: MF
authors.lastname: Addis
authors.affiliation: Dipartimento di Medicina Veterinaria, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Bronzo
authors.affiliation: Porto Conte Ricerche, SP 55 Porto Conte/Capo Caccia, Km 8.400, Loc. Tramariglio, 07041 Alghero, Italy.
authors.forename: G M G
authors.initials: GMG
authors.lastname: Puggioni
authors.affiliation: Porto Conte Ricerche, SP 55 Porto Conte/Capo Caccia, Km 8.400, Loc. Tramariglio, 07041 Alghero, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Cacciotto
authors.affiliation: Porto Conte Ricerche, SP 55 Porto Conte/Capo Caccia, Km 8.400, Loc. Tramariglio, 07041 Alghero, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Tedde
authors.affiliation: Porto Conte Ricerche, SP 55 Porto Conte/Capo Caccia, Km 8.400, Loc. Tramariglio, 07041 Alghero, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Pagnozzi
authors.affiliation: Dipartimento di Scienze Veterinarie per la Salute, la Produzione Animale e la Sicurezza Alimentare, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Locatelli
authors.affiliation: Dipartimento di Medicina Veterinaria, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Casula
authors.affiliation: Dipartimento di Medicina Veterinaria, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Curone
authors.affiliation: Porto Conte Ricerche, SP 55 Porto Conte/Capo Caccia, Km 8.400, Loc. Tramariglio, 07041 Alghero, Italy; Dipartimento di Scienze Biomediche, Università degli Studi di Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Uzzau
authors.affiliation: Dipartimento di Medicina Veterinaria, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy; Quality Milk Production Services, Animal Health Diagnostic Center, Cornell University, 240 Farrier Road, Ithaca, NY 14853.
authors.forename: P
authors.initials: P
authors.lastname: Moroni
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D023181:Antimicrobial Cationic Peptides; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D005260:Female; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000737:chemistry*; D013210:Staphylococcus; D054804:Cathelicidins
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins
keywords: ELISA; cathelicidin; clinical mastitis; dairy cow; intramammary infection