Coagulase gene polymorphism of Staphylococcus aureus isolated from clinical and sub-clinical bovine mastitis in Isfahan and Chaharmahal va Bakhtiari provinces of Iran

Advances in Diagnostic Approaches and Therapeutic Management in Bovine Mastitis

Mastitis causes huge economic losses to dairy farmers worldwide, which largely negatively affects the quality and quantity of milk. Mastitis decreases overall milk production, degrades milk quality, increases milk losses because of milk being discarded, and increases overall production costs due to higher treatment and labour costs and premature culling. This review article discusses mastitis with respect to its clinical epidemiology, the pathogens involved, economic losses, and basic and advanced diagnostic tools that have been used in recent times to diagnose mastitis effectively. There is an increasing focus on the application of novel therapeutic approaches as an alternative to conventional antibiotic therapy because of the decreasing effectiveness of antibiotics, emergence of antibiotic-resistant bacteria, issue of antibiotic residues in the food chain, food safety issues, and environmental impacts. This article also discussed nanoparticles'/chitosan's roles in antibiotic-resistant strains and ethno-veterinary practices for mastitis treatment in dairy cattle.

Bovine subclinical mastitis-associated methicillin-resistant Staphylococcus aureus, selective genotyping and antimicrobial susceptibility profile of the isolates in Kurdistan province of Iran

Background and Objectives:

Staphylococcus aureus is frequently involved in bovine subclinical mastitis worldwide. Besides, the methicillin-resistant S. aureus (MRSA) carrier state of animals is a matter of worrisome. This study aimed to evaluate the frequency of MRSA, discriminatory geno-analysis and antibiotic resistance scheme of the strains isolated from bovine subclinical mastitis in Kurdistan province of Iran.

Materials and Methods:

A total of 283 samples were collected and analyzed for S. aureus phenotypically and molecularly. SCCmec and coa types, and pvl gene were evaluated using polymerase chain reaction (PCR). Finally, the restriction fragment length polymorphism (RFLP) patterns of coa types and the antimicrobial susceptibility profile of the isolates were assessed.

Results:

Among the 95 isolates of S. aureus, 11 (11.57%) strains were recognized as MRSA. Six, one, and four SCCmec types represented for IVa, IVc, and V were determined, respectively, among which an individual IVa and V determinant harboured pvl gene. Restriction digestion products of 490 bp, 680 bp, and 730 bp of coa bands were generated. Tobramycin, mupirocin, fusidic acid, clindamycin, and chloramphenicol were the most effective drugs against the MRSA isolates.

Conclusion:

The detrimental involvement of S. aureus in bovine subclinical mastitis is proved herein. Besides, the contribution of MRSA and potential contamination of milk and dairy products with the bacterium may impose a serious public health risk. This demands serious and long-lasting efforts to control the infection. The results may be effective in the implementation of accurate controlling strategies.

Genetic Diversity and Virulence Factors of S. aureus Isolated from Food, Humans, and Animals

Staphylococcus aureus is a commensal bacterium in humans and animals able to adapt to multiple environments. The aim of this study was to compare the genetic diversity and virulence profiles of strains of S. aureus isolated from food (29 strains), humans (43 strains), and animals (8 strains). 80 lipase-producing strains belonging to a biobank of 360 isolates, identified phenotypically as S. aureus, were selected. Confirmation of the species was made by amplifying the spA gene and 80% (64/80) of the strains were confirmed within this species. The virulence profile of each of the isolates was determined by PCR. The seA gene coding for enterotoxin A was found in 53.1% of the strains, the saK gene, which codes for Staphylokinase, was amplified in 57.8% of the strains, and, finally, the hlB gene coding for β-Hemolysin was amplified in 17.2%. The profile of antimicrobial resistance was determined by the Kirby Bauer method showing that the strains from food presented greater resistance to erythromycin (40.7%) and ciprofloxacin (18.5%) while in strains isolated from humans were to erythromycin (48.4%) and clindamycin (21.2%). Also, in strains from animals, a high resistance to erythromycin was observed (75%). The frequency of MRSA was 12.5% due to the presence of the mec gene and resistance to cefoxitin. Of the total strains, 68.7% were typed by PCR-RFLP of the coa gene using the AluI enzyme; derived from this restriction, 17 profiles were generated. Profile 4 (490 bp, 300 bp) was the most frequent, containing a higher number of strains with a higher number of virulence factors and antimicrobial resistance, which is associated with greater adaptation to different environments. In this study, a wide genetic diversity of strains of S. aureus from different foods, humans, and animals was found. This demonstrates evolution, genetic versatility, and, therefore, the adaptation of this microorganism in different environments.

Evaluation of Antibiotic Susceptibility Pattern and Distribution of coa Genes in Coagulase-negative S. aureus from Ahvaz, Iran

BACKGROUND

Staphylococcus aureus is one of the important causes of clinical infections that can be more destructive by its antibiotic resistant strains.

OBJECTIVE

This study aimed to determine the antibiotic susceptibility pattern and distribution of mecA and coa genes in clinical isolates of S. aureus.

METHODS

Two hundred seventy-three specimens suspected to S. aureus were taken from hospitals of Ahvaz, southwest of Iran. Isolates were identified by standard microbiologic tests and confirmed by the molecular method. Antimicrobial susceptibility testing was carried out by disk diffusion method. The presence of mecA and coa genes was determined by PCR method.

RESULTS

Of a total of 200 isolates which were tested for coagulase tube test, 143 (71.5%) showed coagulase positive, and 57 (28.5%) showed a coagulase-negative reaction. Antibacterial susceptibility pattern of 200 S. aureus isolates showed the highest and lowest susceptibility rate to linezolid (98%) and ciprofloxacin (42%), respectively. The prevalence of methicillin-resistant S. aureus (MRSA) by detection of mecA gene was estimated as 47.5 % (95/200), of which the rate of MRSA in coagulase positive and negative isolates was 35% (50/143), and 65% (45/57), respectively. Meanwhile, coa gene was detected in 100% of coagulase positive and 28.1% of coagulasenegative isolates.

CONCLUSION

The results of this study showed that the number of atypical CNSA in our area is high. Since the coagulase test is an essential test for diagnosis of S. aureus, our findings regarding the emergence of CNSA are a warning about the misdiagnosis and selection of appropriate treatment approach for S. aureus isolates.

Coagulase gene polymorphism, enterotoxigenecity, biofilm production, and antibiotic resistance in Staphylococcus aureus isolated from bovine raw milk in North West India

Background

Staphylococcus aureus is the predominant bacterium responsible for various diseases in animals and humans. Preventive strategies could be better implemented by understanding the prevalence, genetic patterns, and the presence of enterotoxin and biofilm-producing genes along with the antibiotic susceptibility of this organism. This study was conducted in Rajasthan, the northwestern state of India, holding the largest population of cattle that makes it the second largest milk producer in India and no such prior information is available on these aspects.

Methods

A total of 368 individual quarter bovine raw milk samples were collected from 13 districts of Rajasthan, and screened for the presence of S. aureus. Microbiological and molecular approaches were followed for bacterial identification. Genetic diversity was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) of coagulase gene (coa), whereas enterotoxin and biofilm-producing genes were studied by PCR analysis. Antibiotic strips were employed to study the antibiotic resistance among strains.

Results

In all, 73 S. aureus strains were obtained from 368 bovine raw milk samples out of that only 30 showed the presence of coa. Nine types of coa patterns ranging from 730 to 1130 bp were observed among these isolates. PCR–RFLP of coa distinguished the isolates into 15 genotypic patterns, of which patterns I, IV, V, and VI were predominant. Of the isolates, 30% were positive for sec, 10% for sea, and 3.3% for seb; these genes are responsible for enterotoxin production, whereas all isolates were found positive for icaAD and eno. The prevalence rates of other biofilm-producing genes fnbA, clfB, ebpS, sasG, fnbB, sasC, cna, bap, fib and, bbp were 97, 93, 90, 80, 80, 77, 53, 27, 10, and 6.6%, respectively. Twenty-seven (90%) strains were multidrug resistant, of which 15 were methicillin resistant. Maximum sensitivity was reported for kanamycin and it could be considered as a drug of choice for controlling S. aureus mediated cattle infections in the studied regions.

Conclusions

Overall, these strains could cause several diseases to humans, insisting the need for developing a stricter hygiene program for improving milking practices and animal health.

Detection of newly defined superantigenic toxin genes and coagulase gene polymorphism in Staphylococcus aureus isolates

The current study aims to use coagulase (coa) polymorphism gene to identify Staphylococcus aureus isolated from stool samples, evaluate the efficiency of these methods in discriminating variable strains, and compare these subtypes with antibiotypes. A total of 100 specimens were collected from patients in Babylon province, Iraq, between July 2016 and September 2016. Twenty S. aureus strains were isolated and identified using standard laboratory microbiological tests. The bacterial isolates were then examined by coa gene restriction fragment length polymorphism genotyping. Out of 20 isolates, coa gene types were classified, and the amplification products showed multiple size bands (500, 600, 700, 800, and 900-bp bands). Coa gene PCR restriction fragment length polymorphisms exhibited seven patterns that ranged from one to four fragments with AluI digestion. The results have demonstrated that many variants of the coa gene are present. At least one type of S. aureus newly described enterotoxin gene (staphylococcal enterotoxins) was harboring in all 20 (100%) of the isolates. The most frequently encountered gene were sei (100.%), seh (5%), seg (65%). Many S. aureus isolates carry at least one of the enterotoxin genes, and (95%) strains harbored more than one toxin gene coding.

Typing of Staphylococcus aureus obtained from mastitic milk of cattle and buffalo on the basis of two virulence-associated genes (spa and clfA)

Aim:

The present study was undertaken to type Staphylococcus aureus isolates from cattle and buffalo mastitic milk on the basis of spa (X-region) and clfA genes, both responsible for producing virulence factors.

Material and Methods:

In the present investigation S. aureus isolates were isolated as per standard protocols. Typing of S. aureus was carried out by molecular detection of spa and clfA gene by polymerase chain reaction.

Results:

All the 32 isolates from cattle (16) and buffalo (16) were divisible into seven spa types with amplicon sizes ranging between 120 and 380bp. The cattle isolates produced seven different spa amplicons of 120, 150, 200, 250, 280, 300, and 330 bp with 3, 4, 6, 8, 10, 11 and 12 number of tandem repeats, respectively whereas buffalo isolates were divisible into five spa types with amplicons of 150, 200, 250, 330 and 380 bp having calculated number of repeats of 5, 7, 9, 12, and 14, respectively. Of the total isolates, 24 were considered pathogenic on the basis of more than seven number of tandem repeats. In the present investigation, clfA gene was amplified in 27 isolates from cattle and buffalo producing two different amplicons of 900 and 1000 bp sizes showing polymorphism. The most (71.80%) of the isolates produced amplicons of 900 bp while amplicon size of 1000 bp was produced by four (12.5%) of the isolates.

Conclusion:

The presence of these genes with a wide degree of polymorphism confirmed the pathogenic potential of S. aureus and their association with clinical manifestations in mastitis among cattle and buffalo.