Characterization of Staphylococcus aureus strains isolated from raw milk of bovine subclinical mastitis in Tehran and Mashhad (original) (raw)
Related papers
International Journal of One Health, 2021
Background and Aim: Milk is a chief source of many nutrients. However, we must also bear in mind that it is a potential source for many cases of food poisoning. This study was conducted to investigate the prevalence of cow mastitis and evaluate the presence of enterotoxins and antibiotic resistance patterns in Staphylococcus aureus isolated from milk and contact humans in El-Behira Province, Egypt. Materials and Methods: A total of 680 milk samples from 170 cows and 86 human samples consisting of 43 hand swabs and 43 nasal swabs were analyzed. The milk samples were subjected to the California mastitis test. Results: The general occurrence was 23.1% (157/680) where 48 quarters had clinical mastitis and 109 had subclinical mastitis. Subsequently, S. aureus was isolated in Baird-Parker agar where typical and atypical colonies were selected and submitted to coagulase and complementary tests. Out of 48 samples of mastitic milk studied, 16 (33.3%) showed contamination by S. aureus whereas 109 samples of subclinical mastitis showed contamination in only 18 (16.5%). On the opposite hand, of the 86 human samples, 33 revealed S. aureus contamination, corresponding to 38.37% of the samples. Furthermore, multiplex polymerase chain reaction targeting nuc and the staphylococcal enterotoxin-encoding genes sea, seb, sec, sed, and see were performed after culture, revealing that 88.2% (30/34) of milk samples and 93.9% (31/33) of human samples were variably positive to those genes. Conclusion: The use of nuc gene based PCR is an accurate and rapid method for S aureus isolates detection. A high prevalence of multiple drug-resistant isolates of S. aureus recovered from both human and milk represents further evidence for possible veterinary hazards as well as public hazards, especially to those that consume milk from this region.
Comparative Clinical Pathology, 2012
Staphylococcus aureus is a major causative pathogen of clinical and subclinical mastitis of dairy domestic ruminants. This organism produces a variety of extracellular toxins and virulence factors such as enterotoxin SEI and SEJ that contribute to its pathogenic potential. In this study 25 S. aureus isolates obtained from four dairy herds of Urmia region which is located in West Azerbaijan province in Iran. The tested isolates were identified on the basis of the cultural and biochemical properties, as well as amplification of the aroA gene which is specific for S. aureus. All isolates were also analyzed for the presence of the SEI (sei) and SEJ (sej) encoding genes using polymerase chain reaction (PCR). Seven positive isolates were detected for sei, but sej gene was not detected in any of the total number of 25 isolates. The present study revealed that the PCR amplification of the aroA gene could be used as a powerful tool for identification of S. aureus from the cases of bovine mastitis. Results of the present study also showed that the strains of S. aureus which cause mastitis can potentially produce enterotoxin SEI. Overall, our results suggest that it is of special importance to follow the presence of enterotoxin-producing S. aureus in other dairy products, especially for protecting the consumers from staphylococcal food poisoning.
Veterinary Medicine and Science, 2024
Introduction: Raw milk is a nutrient-rich food, but it may harbour harmful bacteria, such as enterotoxigenic Staphylococcus aureus (S. aureus), which can cause staphylococcal food poisoning. Antibiotic resistance of S. aureus in raw milk can increase the risk of such infections, particularly among susceptible individuals. Objective: This study aimed to investigate the prevalence of enterotoxin genes a, d, g, i and j and the antibiotic resistance of S. aureus isolated from raw milk samples. Methods: During a 6-month sampling period, 60 raw milk specimens were obtained from diverse locations in Yazd province, Iran. Antibiogram profiling was conducted via the disc diffusion method. In addition, staphylococcal enterotoxin (SE) genes a, d, g, i, and j were detected through real-time PCR analysis. Results: Bacteriological assays confirmed the presence of S. aureus in 11 samples (18.3%). All isolates demonstrated 100% resistance to penicillin G but exhibited sensitivity to vancomycin, while resistance to other antibiotics ranged from 36.4% to 45.5%. The prevalence of enterotoxin genes in these strains showed variable distribution, with sea being the predominant SE (45.5%), followed by sed (36.4%), seg (18.2), sej and sei (9.1% each). Conclusions: This study discovered the presence of multiple enterotoxins in S. aureus strains obtained from raw milk samples. These strains also demonstrated resistance to a variety of antibiotics. Since enterotoxigenic S. aureus is known to cause human food poisoning, monitoring food hygiene practices, especially during raw milk production, is critical.
Journal of Human Environment and Health Promotion, 2019
"Background: Staphylococcus aureus is one of the major causes of food poisoning. Since milk is a nutritious source of proteins and vitamins, it could provide the optimal conditions for the growth of several bacterial pathogens, such as S. aureus. The present study aimed to assess the frequency of Staphylococcus aureus classical enterotoxin genes in raw milk samples in Zanjan, Iran. Methods: In total, 82 bovine, unpasteurized milk samples were collected from the dairy farms in various rural areas in Zanjan, Iran. The isolation and identification of S. aureus were performed using the Baird-Parker agar, routine biochemical tests, and polymerase chain reaction (PCR) targeting the S. aureus-specific femA gene. In addition, staphylococcal enterotoxin genes (e.g., sea, seb, sec, sed, and see) were assessed using PCR. Results: Following the appearance of yellow colonies with yellow zones on Mannitol salt agar, 21 S. aureus isolates (25.6%) were detected. In total, 80.9% of the isolates were positive for the presence of SE genes, and the most frequent SE gene was sea (88.2%), followed by see (58.8%), and seb (52.9%). Furthermore, 76.5% of the isolates had two or more SE genes simultaneously. Conclusion: According to the results, the presence of enterotoxigenic S. aureus in the studied raw milk samples confirmed the possible risk posed on the public health. Therefore, it is recommended that the quality of dairy product quality programs be optimized in order to intensify the sanitary inspection of these products."
Indian Journal of Comparative Microbiology, Immunology and Infectious Diseases, 2016
To understand the prevalence and characteristics of Staphylococci causing goat mastitis in Algeria, mastitis milk samples were collected and cultured on both blood agar and mannitol salt 2 agar medium. Staphylococci isolates were identified by API-Staph gallery and tested for antibiotic susceptibility by disk diffusion method. DNA microarrays analysis was performed on S. aureus strains in order to detect virulence factors, including toxins, and to assign the isolates to theirs MLST clonal complexes. Overall, 86/266 (32.3%) goats suffered from mastitis, whose 32.5% (28/86) infected with Staphylococci. Most of strains were susceptible to many antibiotics, except for penicillin, tetracycline and fusidic acid, and the resistance incidence of which were 21.4%, 25%, and 10.7% respectively. Only twelve (42.8%) isolates were resistant to utmost two antibiotics and bi-drug resistance was associated to four Coagulase negative Staphylococci (CNS) strains. Nine different species were identified in CNS isolates while S. aureus strains were clustered within CC130-agr3-[lukF-P83, lukM+] (four isolates; 50%), CC6-agr1 (three isolates; 37.5%) and one agr4 non-typables cluster. Enterotoxins genes were found in 62.5% of the S. aureus strains. Of which sec, sel were the most prevalent (62.5%: n=5) followed by sea (12.5%: n=1). CC130 showed edinB, tst and tetK (2/4) genes and CC6 were positive to cna and fosB genes. The current investigation provide the data for prevalence of Staphylococci in goats in Tizi-Ouzou region and S. aureus characterization which will help in tracking evolution of epidemic strains and their control methods.
The study was carried out from July 2010 to June 2011. The aim of the present investigation was to isolate Staphylococcus aureus from raw milk obtained from cow from different parts of Nagpur district, India and to determine their antibiotic susceptibility profile. General biochemical tests along with the MASTASTAPH TM rapid agglutination tests were employed for bacterial identification. All the well characterized isolates were further confirmed by amplifying coa gene by PCR. A total 95 S. aureus isolates were obtained during this study from 50 raw milk samples. When all the well characterized isolates were subjected to antibiotic susceptibility testing, erythromycin and chloramphenicol were the most effective antibiotics. A large proportion of isolates were found to be resistant to Co-trimoxazole (89%) followed by Linomycin (81%) and Penicillin (35%) It was concluded from the current study that the hygiene of the milk was poor and resistant strains contaminated the milk probably during the process of transportation.
Staphylococcus aureus is commonly associated with mastitis in dairy herds with potential public health implications. This study was conducted to investigate the existence of S. aureus in mastitic milk and to determine the antimicrobial resistance profiles of the isolated strains as well as the resistance and virulence associated genes. Materials and Methods: Two hundred quarter milk samples were collected from 3 dairy farms at Dakahliya (n = 2) and Damietta (n = 1) Governorates, Egypt from September to December 2016. Conventional culturing and Polymerase Chain Reaction (PCR) assays targeting nuc (thermonuclease) and coa (coagulase) genes were performed. Isolates were tested for its susceptibility against 14 antimicrobial agents using disk diffusion method. All the isolates were screened for the presence of $-lactamases ( blaZ, mec A) and virulence associated ( pvl and tst ) genes by PCR. Results: The S. aureus was detected in 42% (84/200) of the total examined milk samples. Regarding the antibiogram results, S. aureus revealed a high resistance against ampicillin (95.2%) and penicillin (83.3%) and a lower resistance was observed against gentamicin (23.8%), amikacin (16.7%) and ciprofloxacin (14.3%). Multidrug resistances were detected in 83.3% of the isolated S. aureus . Of the 70 penicillin-resistant S. aureus isolates, blaZ gene was identified in 67 (95.7%) isolates. Fifty percent of S. aureus isolates harbored the specific amplicon of mec A gene. Markedly, all mec A positive strains displayed multidrug resistance and were also positive for blaZ gene. The virulence determinants pvl and tst were detected in 7.1 and 11.9% of the isolated S. aureus , respectively. Conclusion: Presence of multidrug resistant and toxin producing S. aureus in dairy farms pose a major risk to public health. Therefore, this study highlighted the importance of developing an efficient control program to inhibit the transmission of S. aureus , particularly multidrug resistant strains to humans.
Clinical and Vaccine Immunology, 2001
In the present study, 103 Staphylococcus aureus strains isolated from milk samples from 60 cows with mastitis from eight different farms in seven different locations in one region of Germany were compared pheno-and genotypically and by identification of various toxins. On the basis of culture and hemolytic properties and by determination of the tube coagulase reaction, all of the isolates could be identified as S. aureus. This could be confirmed by PCR amplification of species-specific parts of the gene encoding the 23S rRNA. In addition, all of the S. aureus isolates harbored the genes encoding staphylococcal coagulase and clumping factor and the genes encoding the X region and the immunoglobulin G binding region of protein A. These four genes displayed size polymorphisms. By PCR amplification, the genes for the toxins staphylococcal enterotoxin A (SEA), SEC, SED, SEG, SEI, SEJ, and TSST-1 but not those for SEB, SEE, SEH, and the exfoliative toxins ETA and ETB could be detected. To analyze the epidemiological relationships, the isolates were subjected to DNA fingerprinting by macrorestriction analysis of their chromosomal DNAs. According to the observed gene polymorphisms, the toxin patterns, and the information given by macrorestriction analysis of the isolates by pulsedfield gel electrophoresis, a limited number of clones seemed to be responsible for the cases of bovine mastitis on the various farms.
Molecular characterization ofStaphylococcus aureusstrains in bovine mastitis milk in Bangladesh
International Journal of Veterinary Science and Medicine, 2018
Staphylococcus aureus is a common causative agent of bovine mastitis in dairy herds worldwide. This study was designed to assess the prevalence of mastitis in cows through screening tests and molecular characterization of Staphylococcus aureus strains. Out of 175 randomly screened cows, mastitis was detected in 50 cows by California Mastitis Test (CMT), and from those mastitic cows, 200 quarter milk samples were collected for subsequent culture and PCR based identification. The herd, cow and quarter level prevalence of mastitis was 73.3, 28.6 and 29.5% respectively, and subclinical mastitis (SCM) was the predominant type in all cases. According to bacteriology the overall prevalence of herd, cow and quarter level Staphylococcus aureus mastitis was 72.7, 74.0 and 62.0%, respectively, and the pathogen was mostly associated with clinical mastitis (CM). Cows breed, parity, daily milk yield, regular teat dipping, and dry cow therapy were significantly associated (P < 0.05) risk factors for mastitis onset. This study identifies 145 Staphylococcus aureus isolates which varied greatly with the categories of mastitis (higher in CM), udder quarter location (highest in right rear quarters), and to a lesser extent in the study areas (P < 0.05). Antimicrobial susceptibility testing revealed that 79.3% Staphylococcus aureus strains were resistant to at least one antimicrobial, 49.0% to two or more antimicrobials, and clinical isolates showed more resistance to all tested antibiotics. The highest resistance rate was found to oxytetracyclin, and no resistance to ceftriaxone and azithromycin. Seven enterotoxin gene profile were detected in the tested isolates, and mecA was found in 20.0% isolates indicating the emergence and spread of methicillin-resistant Staphylococcus aureus (MRSA). The isolates were carrying genes in combination, and were found higher in SCM cases. In this study, plasmids (> 23 kb to 2.9 kb) were detected in 70.3% strains, and 54.9% plasmid bearing strains were multiple drug resistant (MDR). Thus, the high prevalence of Staphylococcus aureus mastitis is an important concern for diary industry of Bangladesh since the strains of this pathogen is becoming more resistant to commercially available antimicrobials, and this is an alarming concern for both animal and public health.
In Algeria, the milk is consumed directly, generally in the raw state thus escaping any quality control. The subclinical mastitis becomes a problem of food security. Our hypothesis is that consumption of the raw milk of the cows with subclinical mastitis is a tool for transmission of antibiotic resistant staphylococci, which can pass unobserved to man. A total of 981 raw milk samples were obtained from 250 cow's quarters. The California Mastitis test (CMT) has been performed to diagnose the presence of subclinical mastitis. Milk samples were subjected to a bacteriological study and presumptive colonies were confirmed by biochemical characterization using the API-Staph-20 system. The sensitivity tests were performed by disc diffusion method on Muller-Hinton agar, for 13 antibiotics commonly used in veterinary medicine in Algeria, and the VITEK 2 system is used for the determination of the minimum inhibitory concentrations (MIC) for the strains confirmed as S. aureus. The biochemical identification showed that 73.75% of the isolates are CoNS, and that 26.25% are S.aureus. Resistance to penicillin G touches 61.02% of the strains of CoNS that with the tetracycline is of 74.58%. For S. aureus, we found a high resistance to penicillin G 80.95% and with the tetracycline 71.43%. According to our results, 02 (9.52%) isolate is S. aureus resistant to the methicillin , with modified penicillin-binding proteins , identified by the test of the disk of the oxacillin with a diameter of: R≤10 mm, and confirmed by one MIC ≥ 4 µg / l. The MIC of the vancomycin has proved that one strain is a VRSA with one MIC ≥ 32 µg / ml, and a second strain is a hetero-VISA with one MIC ˃ 1 µg / ml. We noted that for the 21 strains of S. aureus, 11 different phenotypes of resistances dominated by resistance to "penicillin G". Our results indicated that there's a multi-resistant staphylococci passage in raw milk consumed in the western region of Algeria, harmful for the health and the security of the consumer, with a higher prevalence of coagulase negative staphylococci compared with S.aureus. Despite unknown pathogenicity of the species, organisms may be the tanks of the resistant to antibiotics; which requires periodic monitoring of antimicrobial resistance of staphylococci in order to control their spread.