Bovine mastitis due to Prototheca zopfii: clinical, epidemiological and pathological aspects in a Brazilian dairy herd

Investigation of Prototheca bovis Infection and Its Correlation with Dairy Herd Improvement Data from a Dairy Farm in Central China

Prototheca bovis (P. bovis), an alga that has attracted considerable attention over the years as a causative microorganism of mastitis in dairy cows, exhibits limited susceptibility to specific aminoglycosides and antifungal agents, and no effective clinical treatment is currently available, thereby posing challenges for both prevention and treatment. To investigate the infection of P. bovis mastitis and its impact on raw milk production, a total of 348 raw milk samples were collected from August to December 2022 from a dairy farm in central China. P. bovis and other bacteria were detected, and the average infection rate of P. bovis in raw milk was 60.34% (210/348). The total number of colonies and the somatic cell count (SCC) of P. bovis positive samples were significantly higher than those of P. bovis negative samples (p < 0.01). The daily milk yield, 305-day milk yield, peak milk yield, and days to peak milk yield of the P. bovis positive samples were significantly lower than those of P. bovis negative samples (p < 0.01). A correlation analysis showed that P. bovis infection was negatively correlated with daily milk yield, 305-day milk yield, peak milk yield, and days to peak milk yield (p < 0.0001), while being positively correlated with the total number of colonies, SCC, milk loss, and protein percentage (p < 0.0001). These findings may help practitioners in comprehending the occurrence of Prototheca mastitis and developing more effective strategies for the prevention of P. bovis infections.

Prototheca spp. induce an inflammatory response via mtROS-mediated activation of NF-κB and NLRP3 inflammasome pathways in bovine mammary epithelial cell cultures

Emergence of bovine mastitis caused by Prototheca algae is the impetus to better understand these infections. Both P. bovis and P. ciferrii belong to Prototheca algae, but they differ in their pathogenicity to induce inflammatory responses. The objective was to characterize and compare pathogenesis of inflammatory responses in bMECs induced by P. bovis versus P. ciferrii. Mitochondrial ultrastructure, activity and mtROS in bMECs were assessed with transmission electron microscopy and laser scanning confocal microscopy. Cytokines, including TNF-α, IL-1β and IL-18, were measured by ELISA and real-time PCR, whereas expressions of various proteins in the NF-κB and NLRP3 inflammasome pathways were detected with immunofluorescence or Western blot. Infection with P. bovis or P. ciferrii damaged mitochondria, including dissolution and vacuolation of cristae, and decreased mitochondrial activity, with P. bovis being more pathogenic and causing greater destruction. There were increases in NADPH production and mtROS accumulation in infected bMECs, with P. bovis causing greater increases and also inducing higher cytokine concentrations. Expressions of NF-κB-p65, p-NF-κB-p65, IκBα and p-IκBα proteins in the NF-κB pathway, as well as NLRP3, Pro Caspase1, Caspase1 p20, ASC, Pro IL-1β, and IL-1β proteins in the NLRP3 inflammasome pathway, were significantly higher in P. bovis-infected bMECs. However, mito-TEMPO significantly inhibited production of cytokines and decreased expression of proteins in NF-κB and NLRP3 inflammasome pathways in bMECs infected with either P. bovis or P. ciferrii. In conclusion, P. bovis or P. ciferrii infections induced inflammatory responses in bMECs, with increased mtROS in damaged mitochondria and activated NF-κB and NLRP3 inflammasome pathways, with P. bovis causing a more severe reaction.

A survey of Prototheca bovis infection in dairy farms of the Hubei province, China

Bovine mastitis, caused by Prototheca bovis, has received much attention worldwide. To investigate the status of P. bovis infection in dairy farms of Hubei, we collected 1,158 milk samples and 90 environmental samples from 14 dairy farms of Hubei, China. The isolates were identified with traditional biological methods and molecular biological techniques, and their pathogenicity was tested through mice infection experiments. Isolates from 57 milk and 20 environmental samples were identified as P. bovis. The mice infection tests proved that the isolated P. bovis could cause mastitis in mice, manifesting as severe red swelling of the mammary glands. Histopathological analysis of tissue sections showed necrosis and nodules lesions formed in the infected mice mammary tissue, accompanied by macrophage and neutrophil infiltration. These results suggested the existence of pathogenic P. bovis in dairy farms of the Hubei province, China, with brewer's grains and fresh feces possibly playing important roles in the spread of this disease.

A novel TaqMan qPCR assay for rapid detection and quantification of pro-inflammatory microalgae Prototheca spp. in milk samples

Animal or human protothecosis belongs to rather rare, endemic, pro-inflammatory infections. It is caused by achlorophyllous algae of the genus Prototheca. Especially, P. bovis (formerly P. zopfii genotype 2) is often inflected as a non-bacterial causative agent of dairy cattle mastitis. In this study, we present a multiplex real-time PCR (qPCR) system for rapid and exact Prototheca spp. detection and quantification. Limit of detection, diagnostic sensitivity, and specificity were determined. For the first time, specific sequences of AccD (encoding acetyl CoA reductase) for P. bovis, cox1 (encoding cytochrome C oxidase subunit 1) for P. wickerhamii, cytB (encoding cytochrome B) for P. blashkeae and atp6 (encoding transporting ATPase F0 subunit 6) for P. ciferrii (formerly P. zopfii genotype 1) were used for species identification and quantification together with 28S rRNA sequence detecting genus Prototheca. The developed qPCR assay was applied to 55 individual cow milk samples from a herd suspected of protothecosis, 41 bulk milk samples from different Czech farms, 16 boxed milk samples purchased in supermarkets and 21 environmental samples originating from a farm suspected of protothecosis. Our work thus offers the possibility to diagnose protothecosis in the samples, where bacterial mastitis is the most commonly presumed and thereby assisting adequate corrective measures to be taken.

Prototheca from bovine milk and associated minimal algaecide concentration of chlorhexidine and povidone-iodine in Taiwan

OBJECTIVE

Protothecal mastitis has emerged and affected the dairy industries globally in last decades; however, little is known about the occurrence of Prototheca in Taiwan. The present study identified the Prototheca isolated from bovine milk and revealed the algaecide efficacy of 2 disinfectants.

MATERIAL AND METHODS

From 2011 to 2014, a total of 176 Prototheca isolates were obtained from 10 625 milk samples collected from dairy cows in 24 Taiwanese dairy farms. Of these, 149 isolates were identified by biochemical tests and genotype differentiation with a specific PCR protocol. Minimal algaecide concentration (MAC) of chlorhexidine and povidone-iodine were obtained from 16 isolates by microdilution method.

RESULTS

Almost all (n = 147) isolates were P. zopfii, and remaining 2 isolates were P. wickerhamii and unidentified, respectively. Based on molecular genotyping, all P. zopfii isolates belonged to genotype 2. The MAC of 2 commonly used disinfectants, chlorhexidine and povidone-iodine, against 16 P. zopfii isolates was 1.56-3.13 and 48.83-390.63 µg/ml, respectively.

CONCLUSION

This report revealed for the first time the prevalence and the predominant P. zopfii genotype 2 of bovine protothecal infection in Taiwan. In vitro algaecide efficacy indicated that both tested disinfectants were effective against P. zopfii.

Mastites em ruminantes no Brasil

Resumo: A mastite é uma doença complexa e considerada uma das principais causas de perdas à indústria leiteira mundial. Objetivou-se com esta revisão compilar informações dos últimos dez anos sobre a mastite em ruminantes no Brasil. A prevalência da mastite subclínica chega a 48,64% na espécie bovina, 30,7% na espécie caprina, 31,45% na espécie ovina e 42,2% na espécie bubalina, destacando-se a etiologia por Staphylococcus spp. Os fatores de risco associados à ocorrência de mastite estão relacionados a problemas no saneamento ambiental e ao manejo dos animais. As bactérias isoladas do leite mastítico apresentam maior percentual de resistência a penicilina, ampicilina, amoxicilina e neomicina e a utilização de técnicas moleculares no diagnóstico dos agentes causadores de mastites no país, ainda é escassa o que dificulta a obtenção de um diagnóstico mais rápido, sensível e específico.

Cutaneous Disease as Sole Clinical Manifestation of Protothecosis in a Boxer Dog

Prototheca wickerhamii is ubiquitous, saprophytic achlorophyllous algae that cause opportunistic infections in the dog and cat and disseminated disease usually in immunocompromised animals. In this report an uncommon case of canine cutaneous protothecosis is presented. A 6-year-old female boxer was brought in with skin lesions that consisted of nodules and generalized footpad hyperkeratosis, depigmentation, and erosion. Cytology and histopathology showed pyogranulomatous inflammation along with organisms containing round sporangia with spherical sporangiospores. PCR and sequencing identified the causal organism as Prototheca wickerhamii. Therapy applied in this patient with either fluconazole alone or combination of amphotericin B and itraconazole proved effective only for footpad lesions but not for skin nodules. Systemic therapy seems to be ineffective for skin nodules, at least in chronic cases of canine cutaneous protothecosis. Although canine protothecosis usually presents with the disseminated form, cutaneous disease as sole clinical manifestation of the infection may also be witnessed.

Biofilm-producing ability and efficiency of sanitizing agents against Prototheca zopfii isolates from bovine subclinical mastitis

The objectives of the present study were to evaluate (1) the capacity of the microalga Prototheca zopfii isolated from subclinical bovine mastitis cases to form biofilms; and (2) the resistance of these isolates to sanitizing agents. Ten isolates of P. zopfii from cows with subclinical mastitis (somatic cell count>200×10(3) cells/mL), distributed in 5 dairy farms, were evaluated for their capacity to form biofilms in polystyrene microplate assays and stainless steel coupons, at 25°C and 37°C±1°C. Prototheca zopfii were isolated from milk samples via microbiological culture and analyzed by 18S rRNA gene sequencing. Biofilm formation on the coupons was observed by scanning electron microscopy. The resistance to sanitizing agents was assessed using the biofilm-forming P. zopfii isolates in stainless steel coupon assays, which were subjected to 3 sanitizers: peracetic acid, sodium hypochlorite, and iodine solution. To evaluate resistance to the sanitizers, the minimum inhibitory concentration (MIC) technique was performed using decreasing concentrations of the sanitizing agents (20, 10, 5, 2.5, 1.25, 0.625, 0.312, 0.156, 0.078, 0.039, and 0.019 g/L). After inoculating the isolates, all concentrations were evaluated at 3 distinct incubation periods (24, 48, and 72 h) to assess the effect of incubation time on the MIC. Using the polystyrene microplate assays, 1 isolate showed weak biofilm production, 5 moderate, and 4 strong, when incubated at 25°C±1. For isolates incubated at 37°C±1, 6 showed weak biofilm production and 4 moderate. All P. zopfii isolates (n=10) had the capacity to form biofilms on stainless steel coupons. The longer the incubation period of the P. zopfii isolates at different dilutions, the greater the concentrations of sanitizer needed to prevent growth of the microalgae under the tested conditions. We detected a significant effect of sanitizer and time of incubation (24, 48, and 72 h) on MIC values against P. zopfii isolates. The isolates were sensitive in vitro to peracetic acid (MIC90≥0.019 g/L), sodium hypochlorite (MIC90≥0.312 g/L), and iodine solution (MIC90≥0.625 g/L), after 24 h of incubation (where MIC90=concentration needed to inhibit 90% of isolates). Of the tested sanitizers, peracetic acid had the greatest efficiency against P. zopfii. We conclude that P. zopfii isolates are capable of biofilm production, which may contribute to their persistence in a milking and dairy environment.

Simultaneous identification by multiplex PCR of major Prototheca spp. isolated from bovine and buffalo intramammary infection and bulk tank

Bovine mastitis caused by Prototheca spp. infection is increasing worldwide, therefore becoming more relevant to the dairy industry. Almost all Prototheca isolates from bovine mammary protothecosis came from P. zopfii genotype 2, with a lower prevalence of infection due to P. blaschkeae and rarely to P. wickerhamii. In this study, we report the development of two multiplex PCR assays able to discriminate among the three species responsible for bovine intramammary infection (IMI). Our assay is based on the specific amplification of new DNA target from mitochondria and chloroplasts partial sequences, of different Prototheca isolates. Both methods were set up using reference strains belonging to all Prototheca species and validated by the analysis of 93 isolates from bovine and buffalo IMI and bulk tank milk samples. The investigation involves 70 isolates from North, 13 from Central and 10 from South Italian regions. Isolates from bovine were most commonly identified as P. zopfii genotype 2, and only in one case as P. blaschkeae, whereas isolates from buffaloes belonged both to P. zopfii genotype 2 and P. wickerhamii. These findings proved the suitability of our multiplex PCRs as a rapid test to discriminate among pathogenic Prototheca strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work reports PCR assays based on novel Prototheca spp. mitochondrial and chloroplastic target sequences. The multiplex PCR protocol described in this study is useful for rapid simultaneous detection of P. zopfii, P. wickerhamii and P. blaschkeae.

Etiology, antimicrobial susceptibility profile of Staphylococcus spp. and risk factors associated with bovine mastitis in the states of Bahia and Pernambuco

The purpose of this paper was to study the etiology of mastitis, determine the antimicrobial susceptibility profile of Staphylococcus spp. and to identify the risk factors associated with infection in dairy cows in the states of Bahia and Pernambuco, Brazil. From the 2,064 milk samples analyzed, 2.6% were associated with cases of clinical mastitis and 28.2% with subclinical mastitis. In the microbiological culture, Staphylococcus spp. (49.1%) and Corynebacterium spp. (35.3%) were the main agents found, followed by Prototheca spp. (4.6%) and Gram negative bacilli (3.6%). In the antimicrobial susceptibility testing, all 218 Staphylococcus spp. were susceptible to rifampicin and the least effective drug was amoxicillin (32.6%). Multidrug resistance to three or more drugs was observed in 65.6% of Staphylococcus spp. The risk factors identified for mastitis were the extensive production system, not providing feed supplements, teat drying process, not disinfecting the teats before and after milking, and inadequate hygiene habits of the milking workers. The presence of multiresistant isolates in bovine milk demonstrates the importance of the choice and appropriate use of antimicrobial agents. Prophylactic and control measures, including teat antisepsis and best practices for achieving hygienic milking should be established in order to prevent new cases of the disease in herds.

Treatment with gentamicin on a murine model of protothecal mastitis

The aim of this study was to establish a murine protothecal mastitis model and to evaluate the treatment efficiency of gentamicin. Challenge routes were determined with a pathogenic Prototheca zopfii genotype 2 (P. zopfii) strain. 25 BALB/c mice were inoculated in mammary glands with graded dosages (10(3), 10(4), 10(5), 10(6), 10(7) CFU of P. zopfii) and killed on the 7th day. Another 25 animals were also killed at 1, 3, 5, 7, and 9 days after inoculation of 1 × 10(6) CFU of P. zopfii, the milk somatic cell counts, pathological section of mammary glands, and P. zopfii burden were observed. The antimicrobial activity was tested using disc diffusion test and minimum inhibitory concentrations. Gentamicin was given intramuscularly to analyze the therapeutic effect. The results showed that the best infection route was intra-mammary gland, and the mastitis model was established with 1 × 10(6) CFU of P. zopfii. After infection, the somatic cell counts increased significantly. The pathological reaction mainly consisted of infiltration of inflammatory cells, destruction of acini, accumulation of lymphocyte cells and the severity of the changes was dosage and time-dependent. The P. zopfii burden revealed that P. zopfii continuously replicated. In vitro susceptibility tests indicated that the Prototheca strains were antimicrobial susceptible to gentamicin at concentrations between 0.03 and 4 μg/ml. In vivo therapeutic assay demonstrated that high concentrations of gentamicin (≥20 mg/kg) could inhibit the growth of P. zopfii. We conclude that the murine model of protothecal mastitis was established successfully and gentamicin may be an effective choice for treatment of P. zopfii.

Algal Meningoencephalitis due toProtothecaspp. in a Dog

A 6-year-old Boxer was examined because of progressive neurologic signs, with severe hindlimb ataxia and head tilt on presentation. There was no history of diarrhea or vomiting. MRI of the brain revealed multifocal ill-defined T1-enhancing lesions affecting the cerebrum, brainstem, and cervical meninges, without associated mass effect. Meningoencephalitis was considered the most likely diagnosis. Multiple algae were observed on the cytology of the CSF and were most consistent withProtothecaspp. Antiprotozoal treatment was denied by the owners, and 5 weeks after diagnosis, the dog was euthanized due to progression of the neurologic deficits, and a necropsy was performed. Histological changes in the brain were compatible with severe multifocal protothecal meningoencephalitis. The specificProtothecaspecies was not identified. The gastrointestinal tract was unremarkable on histology. According to this report,Protothecaspp. should be included in the differentials for neurological deficits even in the absence of gastrointestinal signs.

Herd characteristics and cow-level factors associated with Prototheca mastitis on dairy farms in Ontario, Canada

Prototheca spp. are algae that cause incurable acute or chronic mastitis in dairy cows. The aim of this case-control study was the identification of cow- and herd-level risk factors for this unusual mastitis pathogen. Aseptically collected composite milk samples from 2,428 milking cows in 23 case and 23 control herds were collected between January and May 2011. A questionnaire was administered to the producers, and cow-level production and demographic data were gathered. In 58 of 64 isolates, Prototheca spp. and Prototheca zopfii genotypes were differentiated using PCR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. All isolates were identified as Prototheca zopfii genotype 2. The mean within-herd prevalence for Prototheca spp. was 5.1% (range 0.0-12.5%). Case herds had a significantly lower herd-level prevalence of Staphylococcus aureus and a higher prevalence of yeasts than did control herds. The final logistic regression model for herd-level risk factors included use of intramammary injections of a non-intramammary drug [odds ratio (OR) = 136.8], the number of different injectable antibiotic products being used (OR = 2.82), the use of any dry cow teat sealant (external OR = 80.0; internal OR = 34.2), and having treated 3 or more displaced abomasums in the last 12 mo OR = 44.7). The final logistic regression model for cow-level risk factors included second or greater lactation (OR = 4.40) and the logarithm of the lactation-average somatic cell count (OR = 2.99). Unsanitary or repeated intramammary infusions, antibiotic treatment, and off-label use of injectable drugs in the udder might promote Prototheca udder infection.

Characterization of Prototheca zopfii associated with outbreak of bovine clinical mastitis in herd of Beijing, China

Prototheca zopfii (P. zopfii) has become an important cause of bovine mastitis in many countries. In the present study, to better understand the occurrence of one clinical mastitis (CM) outbreak due to P. zopfii, the molecular characterization and resistance patterns of the microalga were described. P. zopfii strains were isolated from 17 of 23 quarters, which suffered CM in the outbreak, and 7 of 46 CM recovered quarters before the outbreak, as well as 2 of 75 environmental samples in the dairy farm. All strains were identified as genotype 2 by genotype-specific PCR analysis. Results of in vitro antimicrobial and antifungal susceptibility tests indicated that these strains were resistant to majority of tested drugs, with the only exception of amphotericin B, nystatin, streptomycin, gentamicin, and amikacin. This is the first report about CM outbreak caused by P. zopfii in China. These data suggest that P. zopfii may represent a serious risk in the studied herd, and this microalga could be an important potential pathogen causing mastitis in dairy herds of Beijing.

Cutaneous and nasal protothecosis in a goat

A case of protothecosis is reported in an adult goat with inspiratory dyspnea and stertor. Dermatitis with prominent ulcerated nodules up to 3 cm in diameter was observed in the muzzle at the mucocutaneous junctions of nasal and lip skin, and in the border of the pinna. Histologic lesions were necrotizing pyogranulomatous dermatitis and rhinitis with myriads of walled sporangia, characteristic of Prototheca wickerhamii. This seems to be the first report of protothecosis in a goat.

Effect of Prototheca zopfii on neutrophil function from bovine milk

This study was carried to investigate neutrophil function in the presence of Prototheca zopfii. For this purpose, bovine milk neutrophils were incubated in the absence (control) of and presence of P. zopfii, and then they were examined hydrogen peroxide (H(2)O(2)) production, antioxidant enzyme activities, and phagocytic capacity. Milk was collected from negative "California Mastitis Test" (CMT) quarter from three lactating Holstein cows after induction of leukocytosis with an intramammary infusion of oyster glycogen. H(2)O(2) production was measured using the phenol red method. Catalase activity was measured following H(2)O(2) reduction at 240 nm and the activity of glutathione reductase was determined by measuring the rate of NADPH oxidation at 340 nm. P. zopfii death was assessed by fluorescent microscopy using acridine orange assay and by colony forming units (CFUs). Comparisons between the groups were initially performed by analysis of variance (ANOVA). Significant differences were then compared using Tukey's test with a significance coefficient of 0.05. Hydrogen peroxide production, catalase and glutathione reductase activities by neutrophils incubated in presence of P. zopfii were stimulated five times, 21% and 27% respectively, compared to the unstimulated-neutrophils. Neutrophils did not affect P. zopfii death as shown by microscopy and CFUs. These observations led to the conclusion that the P. zopfii promote a high increase of H(2)O(2) production by neutrophils from bovine milk during algae exposition accompanied by increase of antioxidant enzyme activities; however, this process did not affect P. zopfii death.

Epidemiological and clinical aspects of the first outbreak of bovine mastitis caused by Prototheca zopfii in Goiás State, Brazil

The purpose of this survey was to describe the occurrence of bovine mastitis caused by Prototheca zopfii in Goiás State, Brazil. Samples of milk, environment and udder were taken from a herd of 120 Holstein cows. Sabourauds dextrose agar plates were incubated under aerobic conditions at 37 degrees C/96 h, for microbiological analysis. Somatic cell count and milk composition were also determined. Histological sections from two udders were stained with HE and PAS. Prototheca zopfii was identified in six cows whose milk had a watery appearance. They also showed a pronounced decrease in milk yield, fat and lactose. Pronounced infiltration of mononuclear cells, atrophy of alveoli and fibrosis were observed. The presence of this agent in other herds in the State is highly likely.

Protothecal enteritis as a cause of protein-losing enteropathy in a bull

Prototheca spp are achlorophyllic saprophytic algae found in wastewater, sewage, agricultural waste, and possibly elsewhere in the environment. Infections with these organisms have been reported in cattle, humans, and dogs; affected cattle commonly develop mastitis. A 5-year-old Brahman-cross bull was evaluated because of a history of diarrhea and weight loss. The history and physical examination and clinicopathologic findings were similar to those associated with granulomatous enteritis caused by Mycobacterium avium subsp paratuberculosis (Johne's disease), which is the most common protein-losing enteropathy of cattle. However, diagnostic tests for paratuberculosis yielded negative results. Biopsy specimens from the ileum, jejunum, and ileocecal lymph node were collected for histologic examination and preparation of tissue impression smears; Prototheca-like organisms were identified. Because of the poor prognosis associated with this infection and the lack of safe and economical therapeutic agents for cattle, the owner decided to euthanatize the bull. Infection with Prototheca organisms was confirmed postmortem. As this case illustrates, protothecosis may be a cause of granulomatous enteritis in cattle.