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AIMS: This study aimed to evaluate matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) bacterial subtyping for the rapid detection of biomarkers in Staphylococcus aureus from subclinical bovine mastitis. METHODS AND RESULTS: A total of 229 S. aureus isolates were obtained from milk samples collected from cows with subclinical mastitis using microbiological culture. Staphylococcus aureus isolates were also submitted to PCR analysis targeting the mecA and mecC genes, which are indicative of methicillin resistance. Confirmation of the species was achieved through MALDI-TOF MS analysis. To analyze antimicrobial resistance patterns, the MALDI BioTyper Compass Explorer and ClinProTools Bruker software were employed, and dendrograms were generated using Bionumerics software. CONCLUSIONS: MALDI-TOF MS successfully identified S. aureus at the species level, but no methicillin resistance was observed. Moreover, spectral typing displayed limited similarity when compared to pulsed-field gel electrophoresis (PFGE).
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Mastite Bovina , Infecções Estafilocócicas , Animais , Bovinos , Feminino , Staphylococcus aureus/genética , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Mastite Bovina/diagnóstico , Mastite Bovina/microbiologia , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/veterinária , Infecções Estafilocócicas/microbiologia , BiomarcadoresRESUMO
The study aimed to evaluate the genetic diversity of Staphylococcus aureus causing subclinical mastitis (SM) isolated from dairy cows and to assess the effect of the infection status (transient vs. persistent) on the milk and component yield. A total of six dairy farms in São Paulo state were used for the selection of cows with SM caused by S. aureus. S. aureus strains (n = 56) obtained from three biweekly aseptic mammary quarter milk samplings (n = 1140 from 95 cows) were subjected to MALDI-TOF MS analysis for species confirmation and further PFGE analysis. Intramammary infections (IMI) caused by S. aureus were categorized as transient (T: when only one out of 3 milk samplings had positive isolation of any pulsotype) or persistent (P: when two (P2) or three (P3) milk samplings had positive isolation of identical pulsotype over the consecutive episodes of SM. The SmaI macrorestriction fragment profiles of 56 S. aureus isolates showed a dominant S. aureus clonal pattern (PFGE type A; n = 50; 89.3%) within and among the herds. The SM-causing S. aureus represented a reduction of quarter milk yield of 26.2% in transient and 54.8% in persistent cases as well as a reduction of total solid yield of 38.1% and 49.4%, respectively, when compared with the healthy control quarters. Overall, the greater chance of S. aureus to be persistent is when a dominant clonal pattern is present in the herd which consequently may be associated with the cause of accentuated milk loss.
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Mastite Bovina , Infecções Estafilocócicas , Bovinos , Animais , Feminino , Humanos , Staphylococcus aureus/genética , Fazendas , Mastite Bovina/microbiologia , Brasil , Infecções Estafilocócicas/veterinária , Infecções Estafilocócicas/microbiologia , Leite/microbiologiaRESUMO
Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is a polyphagous pest species capable of feeding on almost all forage and grain crops, although the food quality for the larvae likely varies among plant species and cultivars. The cultivation of grass forage species with grains has increasingly been adopted in Brazil, within both no-tillage and crop-livestock integration systems. In this study, we evaluated the performance of S. frugiperda larvae on 14 forage cultivars of Brachiaria, Panicum, and Cynodon, which are widely used in integrated cropping systems in Brazil. The biological performance of S. frugiperda varied among the cultivars. The larval survival rates were lower on Panicum maximum 'Massai' and P. maximum 'Tamani' cultivars. The insects had the highest performance indexes on Brachiaria brizantha 'Paiaguás', B. brizantha 'Marandu', and B. brizantha 'Xaraés' cultivars, followed by Brachiaria ruziziensis, previously proposed as a standard grass forage for comparisons with other species. On P. maximum, the insect had the lowest performance indexes, with values equal to zero when feeding on the P. maximum 'Massai' and 'Tamani' cultivars. These results will help make management decisions when cultivating grass forage plants in crop production systems in which S. frugiperda infestation is of concern.
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We aimed to evaluate the impact of selective dry cow therapy (SDCT) (protocol 1: antimicrobial combined with internal teat sealant (ITS); vs. protocol 2: ITS alone) on bacterial diversity and the abundance of quarter milk. Eighty high production cows (parity ≤ 3 and an average milk yield of 36.5 kg/cow/day) from the largest Brazilian dairy herd available were randomly selected; milk quarter samples were collected for microbiological culture (MC) on the day of drying-off (n = 313) and on day 7 post-calving (n = 313). Based on the results of the MC before and after calving, 240 quarters out of 313 were considered healthy, 38 were cured, 29 showed new infections and 6 had persistent infections. Mammary quarters were randomly selected based on intramammary information status and SDCT protocols for bacterial diversity analyses. The bacterial diversity was similar when comparing both healthy and cured quarters submitted to both drying-off protocols. Despite healthy cows that were treated at dry-off using only teat sealant showing no alteration in the alpha and beta bacterial diversity, they did show a higher abundance of bacterial groups that may be beneficial to or commensals of the mammary gland, which implies that antibiotic therapy should be reserved for mammary quarters with a history of mastitis.
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SU-8 polymer is an excellent platform for diverse applications due to its high aspect ratio of micro/nanostructure fabrication and exceptional physicochemical and biocompatible properties. Although SU-8 polymer has often been investigated for various biological applications, how its surface properties influence the interaction of bacterial cells with the substrate and its colonization is poorly understood. In this work, we tailor SU-8 nanoscale surface properties to investigate single-cell motility, adhesion, and successive colonization of phytopathogenic bacteria, Xylella fastidiosa. Different surface properties of SU-8 thin films have been prepared using photolithography processing and oxygen plasma treatment. A more significant density of carboxyl groups in hydrophilic plasma-treated SU-8 surfaces promotes faster cell motility in the earlier growth stage. The hydrophobic nature of pristine SU-8 surfaces shows no trackable bacterial motility and 5-10 times more single cells adhered to the surface than its plasma-treated counterpart. In addition, plasma-treated SU-8 samples suppressed bacterial adhesion, with surfaces showing less than 5% coverage. These results not only showcase that SU-8 surface properties can impact the spatiotemporal bacterial behavior but also provide insights into pathogens' prominent ability to evolve and adapt to different surface properties.
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Biofilmes , Polímeros , Polímeros/farmacologia , Aderência Bacteriana , Propriedades de Superfície , Membrana CelularRESUMO
Mn5Si3nanowires are believed to be the building blocks of the newest trends of flexible and stretchable devices in nanoelectronics. In this context , growing Mn5Si3nanowires, as well as characterizing their electronic transport properties provide insight into their phenomenology. In this work, we report on the growth mechanism of Mn5Si3nanowires produced by the metallic flux nanonucleation method, as well as the resistivity measurements of these nanostructures. Our calculation allows us, by using the Washburn equation for pore infiltration, to give a guess on why we obtain Mn-rich nanowires. In addition, some morphological aspects of the diameter-modulated Mn5Si3nanowires were discussed based on the classical nucleation theory. From the resistivity measurements for the smallest diameter among the nanowires, we observed a significant reduction of around 37% of the phonons characteristic temperature by fitting the Bloch-Grünesein formula with other sources of scattering. Our results lead to a better understanding on the recent metallic flux nanonucleation growth method, as well as going a step further into the electronic transport properties of the Mn5Si3nanowires.
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Staphylococcus aureus is a contagious pathogen frequently associated with bovine mastitis in Brazil. Molecular characterization of Staph. aureus isolated from affected mammary quarters of cows with clinical mastitis (CM) can provide data on epidemiological behavior of this pathogen and antimicrobial susceptibility (AMS) assessment at the genotypic level. This study genotypically characterized Staph. aureus isolates recovered from cows with CM and determined the association of genotypes and AMS. A total of 84 Staph. aureus strains identified from affected mammary quarters of cows with CM in 13 dairy herds from Southeastern Brazil were submitted for susceptibility testing to 10 antimicrobials using the technique of minimal inhibitory concentration. The same isolates were also genotyped using the spa-typing methodology. Results showed a high genotypic similarity between the Staph. aureus isolates within and between herds, which were categorized as resistant to most antimicrobials, especially to ß-lactam antibiotics. In addition, differences in AMS were observed among genotypic clusters, which may affect the efficacy of antimicrobials used to treat CM in different dairy herds.
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We evaluated the use of MALDI-TOF MS for the identification of 3 major, dairy-associated Prototheca species, namely, Prototheca bovis (formerly P. zopfii genotype 2), P. blaschkeae, and P. ciferrii (formerly P. zopfii genotype 1). The MALDI-TOF MS spectra established for those species were introduced into the reference spectra library of the Bruker Biotyper MALDI-TOF MS analysis software. Next, 31 Prototheca isolates from Holstein cows with mastitis, from herds located in the midwestern area of São Paulo State, Brazil, were subjected to MALDI-TOF MS profiling. MALDI-TOF MS allowed identification of 22 of 27 P. bovis and 3 of 4 P. blaschkeae isolates with scores >2.0, with 5 of 27 P. bovis and 1 of 4 P. blaschkeae isolates identified only to the genus level. With our extended algae database, MALDI-TOF MS can contribute to quick and effective speciation of Prototheca from mastitis cases.
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Doenças dos Bovinos , Mastite Bovina , Prototheca , Animais , Brasil , Bovinos , Genótipo , Mastite Bovina/diagnóstico , Prototheca/genética , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/veterináriaRESUMO
The aims of the present study were to provide a portrait of the techno-economic status of dairy herds in Minas Gerais, Brazil, particularly with respect to bulk-tank somatic cell count (BTSCC) data, and to examine the herd-level associations of BTSCC with various economic performance indicators (EPI). Data from 543 herds, 1,052 herd-year records in total, spread over 3 years (2015-2017), from the South and Southwest mesoregions of Minas Gerais State were provided by the Brazilian Support Agency to Micro and Small Companies Division Minas Gerais (SEBRAE). Herds had an average of 82 lactating cows per herd, milk yield of 17 L/cow per day, and availability of financial information via routine monthly economic surveys. The EPI data (revenue, gross margin, GM; net margin, NM; profit; break-even point; and operational profitability) of each herd was measured monthly by SEBRAE personnel, and herd-year averages of all variables were computed. Bulk-tank data (SCC, total bacterial count, content of crude protein and fat) taken by producers or dairy processors were recorded by SEBRAE personal; and corresponding herd-year averages were calculated and included in the SEBRAE database. There were 209 selected herds, which passed all edit checks, and which had data for all 3 years. The EPI (all expressed on a per-cow basis, $/cow per year) were analyzed, including the effects of region, year, log (ln) BTSCC, production level, and herd size, together with the random effect of herd nested within region. A high proportion of herds (94.6%) presented data records (herd-years) with an average BTSCC > 200 × 103 cells/mL: 37.8% of herd-year records had BTSCC between >200 and ≤400, 14.5% with BTSCC between >400 and ≤500, 25% with BTSCC between >500 and ≤750, and 17.3% with BTSCC >750. For each unit increase in ln BTSCC, revenue declined by $228.5/cow per year, GM by $155.6/cow per year, and profit by $138.6/cow per year. Herds with cows of lower production (<14 kg/d) presented lower GM ($286.8/cow per year) compared with herds containing cows producing ≥14 kg/d (≥14 and <19 kg/d = $446.5, and ≥19 kg/d = $601.9). The small-scale milk producers (<39 lactating cows) presented lower revenue ($1,914.9/cow per year) and GM ($274.5/cow per year) and consequently a negative profit (-$224.1/cow per year) compared with other herd size categories (≥39 lactating cows). The reduction in milk yield was 641 L/cow per lactation for each unit increase in ln BTSCC; this represented 9.4% of the milk yield per lactation, assuming an average milk production of 6,843.3 L/cow per lactation of cows from herds that had BTSCC ≤ 200 × 103 cells/mL. Consequently, we found a negative association of BTSCC with profit; profit declining from $227.0 to -53.1/cow per year when the BTSCC increased from 100 to 750 × 103 cell/mL. In short, the lower the BTSCC, the greater the revenue, GM and NM, profit, and operational profitability of the herds. The reduction of milk yield was the main factor associated with higher BTSCC.
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Bovinos/fisiologia , Indústria de Laticínios/economia , Lactação/fisiologia , Leite/citologia , Animais , Brasil , Contagem de Células/veterinária , Indústria de Laticínios/métodos , Feminino , Renda/estatística & dados numéricos , Inquéritos e QuestionáriosRESUMO
The aim of this study was to compare the efficacy of two dry-off protocols: (a) dry cow therapy using ciprofloxacin hydrochloride 400 mg followed by the administration of an internal teat sealant composed of 4 g of bismuth subnitrate, and (b) a positive control using dry cow therapy with 250 mg cephalonium followed by the administration of 2.6 g bismuth subnitrate internal teat sealant. A total of 578 Holstein cows selected from 7 commercial herds were randomly allocated into two groups at drying off: (a) ciprofloxacin hydrochloride 400 mg (CH) associated with ITS, n = 1112 mammary quarters/296 cows, or (b) positive control (PC) = cephalonium (250 mg) associated with ITS, n = 1058 mammary quarters/282 cows). A total of 1787 out of 2170 mammary quarters (82%) had negative culture at drying off. The microorganisms most frequently isolated at drying off were CNS (5.62%), Strep. uberis (1.9%), Corynebacterium spp. (1.8%), and Staphylococcus aureus (1.01%). A total of 465 mammary quarters experienced new intramammary infections (NIMIs), and the main microorganisms causing NIMI were CNS (21.94%), Strep. uberis (17.2%), and Pseudomonas spp. (9.7%). The CH protocol was not inferior to PC, as the cure risk of mammary quarters CH-treated was at the noninferiority limit. However, the mammary quarters treated by CH protocol had 24% and 31% lower risk of overall NIMI and NIMI caused by major pathogens, respectively, than mammary quarters dried with the PC protocol. In addition, the mammary quarters treated with CH protocol had a lower risk of CM through the first 60 DIM than those treated with PC protocol. Both DCT protocols showed similar odds of microbiological cure, but the CH protocol had greater prevention against NIMI during dry-off period.