Phenotypical and Mass Spectral Assessment Methods for Identification of Some Contagious Mastitis Pathogens

Abstract

Mastitis is one of the most economic disease affecting dairy cows worldwide. Identification of mastitis pathogens still depends principally on culture and phenotypical method, which is a difficult and timeconsuming. Newly, microbiologists have focused their attention on the use of Mass Spectrometry (MS) for microbial identification, especially Matrix Assisted Laser Desorption Ionization Time-Of-Flight (MALDI-TOF). Therefore, this study was designated to evaluate the ability of MALDI-TOF to identify some contagious mastitis pathogens comparing with phenotypical methods such as API panels and VITEK 2 system. A total of one hundred twenty of Staphylococcus aureus (S. aureus), Coagulase Negative Staphylococci (CNS) and Streptococcus agalactiae (Strept. agalactiae) strains isolated from milk of cows affected by clinical and subclinical mastitis were used in the study. According to the results, ~95% of S. aureus, 100% of CNS and Strept. agalactiae were correctly identified by MALDI TOF MS. All S. aureus isolates were then confirmed by a nuc-based PCR technique. While ~92% of S. aureus, 87% of Strept. agalactiae and 76% of CNS were identified by VITEK 2 system. Moreover, ~89% of S. aureus, 80% of Strept. agalactiae and 72% of CNS were identified by API system. In brief, the results demonstrated that MALDI-TOF is a fast and truthful technique which has the capability to replace conventional identification of several bacterial strains usually isolated in clinical laboratories of microbiology. Therefore, it is recomended that MALDI-TOF MS technology can be regularly used in veterinary laboratories for identification of different species of bacteria, particularly when failure of phenotypic methods forces clinical microbiologists.

Comparison of MALDI-TOF mass spectrometry with phenotypic methods for identification and characterization of Staphylococcus aureus causing mastitis

“…Because the ID32 STAPH system is normally used as a reference approach, results attained with ID32 STAPH are added. In the study of El Behiry et al (2014), 89% of the tested S. aureus strains were correctly identified via the ID32 STAPH system, which matched our study, in which the ID32 STAPH system was able to correctly identify (84%) (in all tests) the Staphylococcal species.…”

“…PMFT is one of powerful, fast, truthful, and correct technique of identifying microorganisms, especially in subclinical and clinical cases of mastitis (Carbonnelle et al, 2007;El Behiry et al, 2014;Elbehiry et al, 2016). The application of PMFT in the diagnosis of mastitis has been demonstrated by Nonnemann et al (2018); it was shown to be a cost-effective and quick method when applied to 500 isolates, and twentyfour genera and sixty-one specifies were identified.…”

Performance of MALDI biotyper compared with Vitek™ 2 compact system for fast identification and discrimination of Staphylococcus species isolated from bovine mastitis

“…MALDI‐TOF‐MS therefore, represents one of the major, fast and correct tool for identification and typing of various microorganisms isolated from clinical and subclinical samples (Carbonnelle et al., ; El Behiry et al., ; Singhal et al., ). In our study, detection and typing of S. aureus and CNS strains were carried out by proteomic analysis and the frequency of precise identification at the genus and species levels was 194/198 (97.97%) and 44/44 (100%), respectively, with the score level ranging from 2,000 to 3,000 Da.…”

“…Bovine mastitis remains one of the most important complications among dairy farms all over the world from the diagnostic, economic, and public health related perspective (Benić et al, ; El Behiry et al., ; Preethirani et al, ). Several cases of mastitis in cattle are caused mainly by different types of bacteria, and the species of Staphylococcus aureus ( S. aureus ) and coagulase‐negative staphylococci (CNS) are considered the most common and important bacteria that cause mastitis, both subclinical and clinical form of mastitis among dairy farms (Cabral et al., ; Haveri, ; Vasudevan et al, ).…”

“…For this reason, there is still a need for supplementary quick, low‐cost, and a precise technique for detection of various microorganisms of infectious diseases. In general, innovative techniques such as MALDI‐TOF‐MS for accurate and fast characterization of different microbes is considered an important step toward suitable prevention and control of communicable diseases in medical and veterinary diagnosis and currently are of major concern (El Behiry et al., ; Hays & Van Leeuwen, ; Sauer et al., ).…”