Biomedical subjects

V Srinivasan

Publications and source records attributed to V Srinivasan.

At least 19 recordsLinked to original sources

PubMed2006

Melatonin in the eye: implications for glaucoma.

Melatonin synthesis occurs in the retina of most animals as well as in humans. Circadian oscillators that control retinal melatonin synthesis have been identified in the eyes of different animal species. The presence of melatonin receptors is demonstrable by immunocytochemical studies of ocular tissues. These receptors may have different functional roles in different parts of the eye. In view that melatonin is a potent antioxidant molecule, it can be effective in scavenging free radicals that are generated in ocular tissues. By this mechanism melatonin could protect the ocular tissues against disorders like glaucoma, age-related macular degeneration, retinopathy of prematurity, photo-keratitis and cataracts. Although an increased intraocular pressure is an important risk factor in glaucoma, other concomitant phenomena like increased glutamate levels, altered nitric oxide metabolism and increased free radical generation seem to play a significant role in its pathogenesis. Data are discussed indicating that melatonin, being an efficient antioxidant with antinitridergic properties, has a promising role in the treatment and management of glaucoma.

Animals↗

PubMed2006

Posterior fossa arachnoid cyst presenting with isolated sensorineural hearing loss.

Arachnoid cysts are benign cysts occurring in the intra-arachnoid space and containing cerebrospinal fluid. They constitute approximately 1 per cent of all intracranial masses. They are uncommon in the posterior cranial fossa. Common presenting symptoms include headaches, seizures, focal neurologic signs and vague dizziness. Magnetic resonance imaging is the preferred method of investigation, and the treatment for symptomatic cysts is generally surgical drainage. We report the unusual presentation of a young patient with a posterior fossa arachnoid cyst that manifested in the form of isolated unilateral sensorineural hearing loss. The patient underwent posterior fossa craniotomy and marsupialization of the cyst. To our knowledge, posterior fossa arachnoid cyst presenting with isolated hearing loss alone has not been reported in the English literature. A review of the literature pertaining to posterior fossa arachnoid cysts, including the clinical features, diagnosis and management, is also presented.

Adult↗

PubMed2006

Melatonin in Alzheimer's disease and other neurodegenerative disorders.

Increased oxidative stress and mitochondrial dysfunction have been identified as common pathophysiological phenomena associated with neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD). As the age-related decline in the production of melatonin may contribute to increased levels of oxidative stress in the elderly, the role of this neuroprotective agent is attracting increasing attention. Melatonin has multiple actions as a regulator of antioxidant and prooxidant enzymes, radical scavenger and antagonist of mitochondrial radical formation. The ability of melatonin and its kynuramine metabolites to interact directly with the electron transport chain by increasing the electron flow and reducing electron leakage are unique features by which melatonin is able to increase the survival of neurons under enhanced oxidative stress. Moreover, antifibrillogenic actions have been demonstrated in vitro, also in the presence of profibrillogenic apoE4 or apoE3, and in vivo, in a transgenic mouse model. Amyloid-beta toxicity is antagonized by melatonin and one of its kynuramine metabolites. Cytoskeletal disorganization and protein hyperphosphorylation, as induced in several cell-line models, have been attenuated by melatonin, effects comprising stress kinase downregulation and extending to neurotrophin expression. Various experimental models of AD, PD and HD indicate the usefulness of melatonin in antagonizing disease progression and/or mitigating some of the symptoms. Melatonin secretion has been found to be altered in AD and PD. Attempts to compensate for age- and disease-dependent melatonin deficiency have shown that administration of this compound can improve sleep efficiency in AD and PD and, to some extent, cognitive function in AD patients. Exogenous melatonin has also been reported to alleviate behavioral symptoms such as sundowning. Taken together, these findings suggest that melatonin, its analogues and kynuric metabolites may have potential value in prevention and treatment of AD and other neurodegenerative disorders.

Journal Article↗

PubMed2006

Preferential radiation sensitization of prostate cancer in nude mice by nutraceutical antioxidant gamma-tocotrienol.

Gamma-tocotrienol (GT) is a member of the vitamin E family. Our preliminary studies indicated that it protected mice from lethal irradiation, so we hypothesized that GT might be a radiation sensitizing agent for tumors. To test this, we induced prostate tumors by injecting PC3 cells into nude BALB/c mice. When the tumors were about 5 mm in diameter, mice were injected subcutaneously with 400 mg/kg gamma-tocotrienol and irradiated 24 h later at the site of the tumor with a dose of 12 Gy (60)Cobalt. Tumor size was monitored for 24 days after radiation. Tumor tissues as well as normal tissues like rectum, kidney, and liver were monitored for lipid peroxidation on day 4 and day 24 after radiation. The results indicated that the size of the tumors was reduced by almost 40%, but only in GT-treated and irradiated mice. In unstimulated and Fe-stimulated lipid peroxidation groups, lipid peroxidation in the tumors from irradiated mice increased to 135% and 150%, respectively, four days after irradiation and 33% and 66% in the same groups, respectively, 24 days after irradiation. In general, lipid peroxidation in the rectum did not increase in GT-treated and irradiated mice, although there was a slight increase in Fe-stimulated lipid peroxidation (29%) four days after irradiation. Unexpectedly, the kidneys were as equally sensitized to lipid peroxidation as the tumors. Liver tissue was protected in the short-term from radiation-induced lipid peroxidation. These studies indicate that the radiotherapy efficacy of prostate cancer can be increased with GT and a pro-oxidant if the kidneys can be shielded.

Animals↗

PubMed2006

Public health significance of antimicrobial-resistant gram-negative bacteria in raw bulk tank milk.

The dairy farm environment and animals on the farm serve as important reservoirs of pathogenic and commensal bacteria that could potentially gain access to milk in the bulk tank via several pathways. Pathogenic gram-negative bacteria can gain access to bulk tank milk from infected mammary glands, contaminated udders and milking machines, and/or from the dairy farm environment. Contaminated raw milk when consumed by humans or fed to animals on the farm can result in gastroenteric infections in humans and animals and also provide an opportunity for organisms to colonize the farm environment. This scenario becomes much more complicated when pathogenic bacteria such as Salmonella, Shiga toxin-producing Escherichia coli, and commensal gram-negative enteric bacteria encode for antimicrobial resistance determinants. In recent years, the role of commensal bacteria as reservoirs of genetic determinants for antimicrobial resistance has come under closer scrutiny. Commensal bacteria in bulk tank milk can be a significant reservoir of antimicrobial determinants. Raw milk consumption can result in exposure to antimicrobial-resistant commensal gram-negative bacteria. This paper examines the prevalence and role of commensal gram-negative enteric bacteria in bulk tank milk and their public health significance.

Animals↗

PubMed2006

Is there life after Buckley's formocresol? Part II - Development of a protocol for the management of extensive caries in the primary molar.

OBJECTIVE: To produce a working clinical protocol for pulp therapy techniques in the extensively carious primary molar. INTRODUCTION: The International Agency for Research on Cancer has recently classified formaldehyde as carcinogenic to human beings. As such, a medicament that can be used to replace formocresol in clinical practice should be identified. METHODS: Part I of this paper explored the currently available alternative interventions and materials to formocresol in the form of a narrative review following an extensive literature search. Part II now presents the formation of a specialist group to establish an evidence-based protocol, for the management of the extensively carious primary molar. CONCLUSION: A protocol and key points document have been developed to assist clinicians in their treatment planning. Areas for further postgraduate training are identified.

Algorithms↗

PubMed2006

Is there life after Buckley's Formocresol? Part I -- a narrative review of alternative interventions and materials.

OBJECTIVES: (1) To present a narrative review of the currently available alternative interventions and materials to formocresol pulpotomy for the management of extensive caries in the primary molar, and (2) to produce a clinical protocol for pulp therapy techniques in the extensively carious primary molar. INTRODUCTION: The International Agency for Research on Cancer has recently classified formaldehyde as carcinogenic to human beings. Since Buckley's Formocresol contains 19% formaldehyde in its full strength and, therefore, 1% in a 20% dilution, a safer alternative should be identified. METHODS: A narrative review of the published literature for primary molar pulp therapy techniques was undertaken following an extensive and appropriate literature search. A specialist group of paediatric dentists was formed to arrive at a consensus and establish an evidence-based protocol for the management of extensively carious primary molar teeth. Part I of this paper explores the currently available alternative interventions and materials to formocresol in the form of a narrative review. The second part of the paper will present the formation of a specialist group to arrive at a consensus and establish an evidence-based protocol for the management of the extensively carious primary molar. CONCLUSIONS: After consideration of a review of extensively searched literature, a protocol and key points document have been developed to assist clinicians in their treatment planning. Further long-term studies with the highest level of evidence (i.e. randomized controlled trials) are required to enable us to identify acceptable alternatives which can replace formocresol.

Aluminum Compounds↗

PubMed2006

Melatonin: Nature's most versatile biological signal?

Melatonin is a ubiquitous molecule and widely distributed in nature, with functional activity occurring in unicellular organisms, plants, fungi and animals. In most vertebrates, including humans, melatonin is synthesized primarily in the pineal gland and is regulated by the environmental light/dark cycle via the suprachiasmatic nucleus. Pinealocytes function as 'neuroendocrine transducers' to secrete melatonin during the dark phase of the light/dark cycle and, consequently, melatonin is often called the 'hormone of darkness'. Melatonin is principally secreted at night and is centrally involved in sleep regulation, as well as in a number of other cyclical bodily activities. Melatonin is exclusively involved in signaling the 'time of day' and 'time of year' (hence considered to help both clock and calendar functions) to all tissues and is thus considered to be the body's chronological pacemaker or 'Zeitgeber'. Synthesis of melatonin also occurs in other areas of the body, including the retina, the gastrointestinal tract, skin, bone marrow and in lymphocytes, from which it may influence other physiological functions through paracrine signaling. Melatonin has also been extracted from the seeds and leaves of a number of plants and its concentration in some of this material is several orders of magnitude higher than its night-time plasma value in humans. Melatonin participates in diverse physiological functions. In addition to its timekeeping functions, melatonin is an effective antioxidant which scavenges free radicals and up-regulates several antioxidant enzymes. It also has a strong antiapoptotic signaling function, an effect which it exerts even during ischemia. Melatonin's cytoprotective properties have practical implications in the treatment of neurodegenerative diseases. Melatonin also has immune-enhancing and oncostatic properties. Its 'chronobiotic' properties have been shown to have value in treating various circadian rhythm sleep disorders, such as jet lag or shift-work sleep disorder. Melatonin acting as an 'internal sleep facilitator' promotes sleep, and melatonin's sleep-facilitating properties have been found to be useful for treating insomnia symptoms in elderly and depressive patients. A recently introduced melatonin analog, agomelatine, is also efficient for the treatment of major depressive disorder and bipolar affective disorder. Melatonin's role as a 'photoperiodic molecule' in seasonal reproduction has been established in photoperiodic species, although its regulatory influence in humans remains under investigation. Taken together, this evidence implicates melatonin in a broad range of effects with a significant regulatory influence over many of the body's physiological functions.

Animals↗

PubMed2006

A study on staging bone scans in newly diagnosed prostate cancer.

OBJECTIVE: This study aimed to evaluate the role of bone scan as a staging investigation in newly diagnosed untreated prostate cancers. MATERIALS AND METHODS: Bone scan results in patients with newly diagnosed prostate cancer were reviewed and correlated with clinical stage, prostate-specific antigen (PSA) and Gleason scores from the biopsy specimen. RESULTS: In all, 124 patients fulfilled inclusion criteria with an age range of 51-94 (mean 72.3) years. Pre-biopsy PSA ranged from 2.2 to 5,864 with a median of 21.1 ng/ml. Clinical stage was T0-T1c 14.5%, T2a 41.9%, T2b 17.7%, T3 16.9%, and T4 9%. A Gleason score of 7 was found in 31%. Four patients' samples were not suitable for Gleason scoring. Twenty patients (16.1%) had a positive bone scan with a mean age of 79.4 years (median 83). Two patients with PSA<20 ng/ml were positive. Of the 44 scans performed in the patients with PSA<or=20 ng/ml, clinical stage<T4 and Gleason sum<or=7 (with the major Gleason<4), none was positive. The above criteria give a 100% negative predictive value for avoiding bone scans as a staging investigation. CONCLUSIONS: Staging bone scan can be safely omitted in patients with a clinical stage of <T4, PSA level of <or=20 ng/ml and a Gleason score of <or=7 (with major Gleason pattern<4) unless the symptoms are suggestive of metastasis.

Aged↗

PubMed2006

Effect of placing a clear sealant on the validity and reproducibility of occlusal caries detection by a laser fluorescence device: an in vitro study.

The principal aim of this in vitro study was to assess the validity and reproducibility of the detection of occlusal caries using laser fluorescence (LF), prior to and following the placement of a clear fissure sealant. It also aimed to compare the manufacturer's standard cut-off recommendations with those published for in vitro studies and to compare the validity and reproducibility of LF with clinical visual examination (CVE) for the detection of occlusal caries under sealants. Three clinicians independently examined visually and with LF 37 extracted teeth (25 molars, 12 premolars), with a range of clinical caries from apparently sound to cavitated dentinal caries. Examinations were conducted under dental surgery conditions. Subsequently, the teeth were serially sectioned to provide the validating criterion. Following placement of the sealant, the specificity generally increased but there was an associated loss of sensitivity, at both the D1 (enamel and dentine) and D3 (dentine) diagnostic thresholds. The LF readings were significantly lower after placement of the sealant (p<0.05). The manufacturer's recommended cut-offs appear to be the most appropriate to use. The CVE had superior validity and reproducibility when compared to LF. Overall, the placement of a clear sealant does influence the detection of caries by LF but does not prevent the detection of caries by this method.

Bicuspid↗

PubMed2005

Melatonin, immune function and aging.

Aging is associated with a decline in immune function (immunosenescence), a situation known to correlate with increased incidence of cancer, infectious and degenerative diseases. Innate, cellular and humoral immunity all exhibit increased deterioration with age. A decrease in functional competence of individual natural killer (NK) cells is found with advancing age. Macrophages and granulocytes show functional decline in aging as evidenced by their diminished phagocytic activity and impairment of superoxide generation. There is also marked shift in cytokine profile as age advances, e.g., CD3+ and CD4+ cells decline in number whereas CD8+ cells increase in elderly individuals. A decline in organ specific antibodies occurs causing reduced humoral responsiveness. Circulating melatonin decreases with age and in recent years much interest has been focused on its immunomodulatory effect. Melatonin stimulates the production of progenitor cells for granulocytes-macrophages. It also stimulates the production of NK cells and CD4+ cells and inhibits CD8+ cells. The production and release of various cytokines from NK cells and T-helper lymphocytes also are enhanced by melatonin. Melatonin presumably regulates immune function by acting on the immune-opioid network, by affecting G protein-cAMP signal pathway and by regulating intracellular glutathione levels. Melatonin has the potential therapeutic value to enhance immune function in aged individuals and in patients in an immunocompromised state.

Journal Article↗

PubMed2005

Genetic manipulation of two fowlpox virus late transcriptional regulatory elements influences their ability to direct expression of foreign genes.

Fowlpox virus (FWPV) is currently used as a vector to express foreign genes of various poultry and mammalian pathogens. However, due to limited information available about the primary structure of FWPV promoters required for an optimal transcriptional efficiency, the full potential of FWPV as an expression vector has not been completely realized. To dissect such transcriptional regulatory elements at the molecular level, we selected two FWPV promoters dictating contrasting levels of expression of acidic-type inclusion body protein gene (P190) and A15L vaccinia virus homolog of FWPV (P180) for site-directed mutagenesis studies. The transcriptional activity of mutated promoters was analyzed based on their ability to transcribe a reporter gene, lacZ, and translation of the resultant mRNA into functional protein. Replacement of the spacer sequences of P180 with those of P190 resulted in a five-fold increase in mRNA and a 17.6-fold increase in protein over those with its parental promoter, P180. Similarly, replacement of a thymidine after the start codon with guanosine resulted in a 2.3-fold increase in lacZ mRNA and a seven-fold increase in protein. Combining these substitutions in P180SG produced a maximum increase in mRNA and protein of 6.7- and 29.9-fold, respectively, over concentrations with its parental P180 promoter. The promoter activity of P180SG was comparable to that of the strongest natural promoter, P190. The amount of protein per transcript generated by the mutated promoters of P180 increased to at least three times that with the parental P180. In contrast, similar replacements in P190 resulted in a 40-50% reduction in mRNA and protein in all the mutated promoters. We discuss the significance of spacer sequence and the purine after the start codon in the context of a high level of expression.

Animals↗

PubMed2005

Melatonin and sleep in aging population.

The neurohormone melatonin is released from the pineal gland in close association with the light-dark cycle. There is a temporal relationship between the nocturnal rise in melatonin secretion and the 'opening of the sleep gate' at night. This association, as well as the sleep promoting effect of exogenous melatonin, implicates the pineal product in the physiological regulation of sleep. Aging is associated with a significant reduction in sleep continuity and quality. A decreased production of melatonin with age is documented in a majority of studies. Diminished nocturnal melatonin secretion with severe disturbances in sleep/wake rhythm has been consistently reported in Alzheimer's disease (AD). A recent survey on the effects of melatonin in sleep disturbances, including all age groups, failed to document significant and clinically meaningful effects of exogenous melatonin on sleep quality, efficiency and latency. However, in clinical trials involving elderly insomniacs and AD patients suffering from sleep disturbances exogenous melatonin has repeatedly been found to be effective in improving sleep. The results indicate that exogenous melatonin is more effective to promote sleep in the presence of a diminished production of endogenous melatonin. A MT1/MT2 receptor analog of melatonin (ramelteon) has recently been introduced as a new type of hypnotics with no evidence of abuse or dependence.

Aged↗

PubMed2005

The DNA repair enzyme, CPD-photolyase restores the infectivity of UV-damaged fowlpox virus isolated from infected scabs of chickens.

Fowlpox virus (FWPV), an important pathogen of poultry, replicates very efficiently in the featherless areas of skin, and persists in dried and desiccated scabs for prolonged periods. Although the molecular mechanisms underlying the stability of the virus are not completely known, we recently identified the presence of a virus-encoded novel DNA repair enzyme, CPD-photolyase, in FWPV. This enzyme repairs the ultraviolet (UV)-induced pyrimidine dimers, converting them to monomers using photons from white light as a renewable source of energy. In this study, we examined the role of photolyase in the pathogenesis of fowlpox. A comparison of pathogenesis of fowlpox in chickens infected with parental FWPV with that in chickens infected with photolyase-deficient FWPV (Phr(-) FWPV) found no significant differences in terms of replication of virus or formation of secondary lesions. When the virions isolated from infected scabs were exposed to UV light, UV-damaged parental FWPV, unlike Phr(-) FWPV, were rescued through the CPD-photolyase-mediated photoreactivation pathway by at least 48%. However, the mutant virus triggered host's immune response and conferred complete protection against subsequent challenge with virus similar to that conferred by the parental virus. Since the mutant virus is less stable than the parental virus in the infected scabs but is as immunogenic, Phr(-) FWPV might be less persistent in the environment. Furthermore, this particular genetic locus can also be used to insert foreign genes for the development of FWPV recombinant vaccines.

Animals↗

PubMed2005

Role of melatonin in neurodegenerative diseases.

The pineal product melatonin has remarkable antioxidant properties. It scavenges hydroxyl, carbonate and various organic radicals, peroxynitrite and other reactive nitrogen species. Melatonyl radicals formed by scavenging combine with and, thereby, detoxify superoxide anions in processes terminating the radical reaction chains. Melatonin also enhances the antioxidant potential of the cell by stimulating the synthesis of antioxidant enzymes like superoxide dismutase, glutathione peroxidase and glutathione reductase, and by augmenting glutathione levels. The decline in melatonin production in aged individuals has been suggested as one of the primary contributing factors for the development of age-associated neurodegenerative diseases, e.g., Alzheimer's disease. Melatonin has been shown to be effective in arresting neurodegenerative phenomena seen in experimental models of Alzheimer's disease, Parkinsonism and ischemic stroke. Melatonin preserves mitochondrial homeostasis, reduces free radical generation, e.g., by enhancing mitochondrial glutathione levels, and safeguards proton potential and ATP synthesis by stimulating complex I and IV activities. Therapeutic trials with melatonin have been effective in slowing the progression of Alzheimer's disease but not of Parkinson's disease. Melatonin's efficacy in combating free radical damage in the brain suggests that it may be a valuable therapeutic agent in the treatment of cerebral edema after traumatic brain injury.

Aging↗

PubMed2005

Artificial neural network based epileptic detection using time-domain and frequency-domain features.

Electroencephalogram (EEG) signal plays an important role in the diagnosis of epilepsy. The long-term EEG recordings of an epileptic patient obtained from the ambulatory recording systems contain a large volume of EEG data. Detection of the epileptic activity requires a time consuming analysis of the entire length of the EEG data by an expert. The traditional methods of analysis being tedious, many automated diagnostic systems for epilepsy have emerged in recent years. This paper discusses an automated diagnostic method for epileptic detection using a special type of recurrent neural network known as Elman network. The experiments are carried out by using time-domain as well as frequency-domain features of the EEG signal. Experimental results show that Elman network yields epileptic detection accuracy rates as high as 99.6% with a single input feature which is better than the results obtained by using other types of neural networks with two and more input features.

Electroencephalography↗

PubMed2005

Detection of Campylobacter jejuni in dairy farm environmental samples using SYBR Green real-time polymerase chain reaction.

The aim of this study was to evaluate a SYBR Green based real-time PCR assay using well-characterized primers to detect Campylobacter jejuni in naturally contaminated dairy farm environmental samples. Specificity of the assay was determined with 62 C. jejuni strains and 120 non-C. jejuni strains. Peak melting temperature obtained with melting curves specific for C. jejuni was 77.5 degrees C. Standard curves were constructed using mean threshold cycle (C(T)) and various concentrations of C. jejuni ranging from 10(0) to 10(8) colony forming units (CFU)/mL, which resulted in a linear relationship between C(T) and log input DNA. Correlation coefficients of standard curves based on pure culture of C. jejuni in broth and spiked cells in lagoon water were R(2) = 0.995 (slope = 3.21) and R(2) = 0.988 (slope = 3.22), respectively, and sensitivity limits were <10 and >10(3) CFU/mL, respectively. After 24-h enrichment, total C. jejuni counts of all samples spiked with 10(0) CFU/mL reached >10(5) CFU/mL, and the detection limit was improved from >10(3) CFU/mL to <10 CFU/mL of inoculum in broth. Eighty-two dairy farm environmental samples, including fecal slurry, feed/silage, lagoon water, drinking water, bulk tank milk, farm soil, and bedding material, were analyzed. The real-time PCR assay detected C. jejuni in 25 (30.4%) of 82 samples, with 17 (68%) of these samples being culture positive for C. jejuni. All samples that were positive by standard culture methods were also positive by the real-time PCR method. Mean C( T ) values of 48-h enriched cultures for 17 PCR-positive/culture-positive samples and eight PCR-positive/culture-negative samples were 21.4 +/- 3.6, and 34.6 +/- 1.5 (p < 0.0001), respectively. C( T ) values for negative samples were >38.0. These results indicate that the SYBR Green real-time PCR assay provides a specific, reproducible, and simple method for detecting C. jejuni in dairy farm environmental samples.

Animals↗

PubMed2005

Prevalence of antimicrobial resistance genes in Listeria monocytogenes isolated from dairy farms.

Antimicrobial resistance of Listeria monocytogenes (n = 38) isolated from the four dairy farms to 15 antimicrobial agents was evaluated. All 38 L. monocytogenes isolates from the four farms evaluated were resistant to more than one antimicrobial in different combinations. All L. monocytogenes isolates evaluated were resistant to cephalosporin C (minimum inhibitory concentration [MIC] > or = 512 microg/mL), streptomycin (MIC > or = 32) and trimethoprim (MIC > or = 512). Most L. monocytogenes isolates were resistant to ampicillin (92%, MIC > or = 2), rifampicin (84%, MIC > or = 4), rifamycin (84%, MIC > or = 4), and florfenicol (66%, MIC > or = 32) and some were resistant to tetracycline (45%, MIC > or = 16), penicillin G (40%, MIC > or = 2) and chloramphenicol (32%, MIC > or = 32). All L. monocytogenes isolates were susceptible to amoxicillin, erythromycin, gentamicin, kanamycin and vancomycin. Susceptibility of L. monocytogenes to the antimicrobials evaluated was quite consistent among the dairy farms evaluated. However, some variability in antimicrobial susceptibility among dairy farms was noted. Nineteen of 38 L. monocytogenes isolates contained more than one antimicrobial resistance gene sequence. A high frequency of floR (66%) was found in L. monocytogenes followed by penA (37%), strA (34%), tetA (32%), and sulI (16%). Other tetracycline resistance genes (tetB, tetC, tetD, tetE, and tetG) and other antimicrobial resistance genes (cmlA, strB, aadA, sulI, vanA, vanB, ampC, ermB, ereA, and ereB) were not found in any of the L. monocytogenes isolates from the four dairy farms. Results of the present study demonstrated that L. monocytogenes isolated from the dairy farm environment were resistant to many antimicrobials and contained one or more antimicrobial resistance genes.

Animals↗