Foodborne Pathogenic Vibrios: Antimicrobial Resistance.

Foodborne illness caused by pathogenic Vibrios is generally associated with the consumption of raw or undercooked seafood. Fish and other seafood can be contaminated with Vibrio species, natural inhabitants of the marine, estuarine, and freshwater environment. Pathogenic Vibrios of major public health concerns are Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus. Common symptoms of foodborne Vibrio infection include watery diarrhea, stomach cramping, nausea, vomiting, fever, and chills. Administration of oral or intravenous rehydration salts solution is the mainstay for the management of cholera, and antibiotics are also used to shorten the duration of diarrhea and to limit further transmission of the disease. Currently, doxycycline, azithromycin, or ciprofloxacin are commonly used for V. cholerae, and doxycycline or quinolone are administered for V. parahaemolyticus, whereas doxycycline and a third-generation cephalosporin are recommended for V. vulnificus as initial treatment regimen. The emergence of antimicrobial resistance (AMR) in Vibrios is increasingly common across the globe and a decrease in the effectiveness of commonly available antibiotics poses a global threat to public health. Recent progress in comparative genomic studies suggests that the genomes of the drug-resistant Vibrios harbor mobile genetic elements like plasmids, integrating conjugative elements, superintegron, transposable elements, and insertion sequences, which are the major carriers of genetic determinants encoding antimicrobial resistance. These mobile genetic elements are highly dynamic and could potentially propagate to other bacteria through horizontal gene transfer (HGT). To combat the serious threat of rising AMR, it is crucial to develop strategies for robust surveillance, use of new/novel pharmaceuticals, and prevention of antibiotic misuse.

Anti-mycobacterial activity of some medicinal plants used traditionally by tribes from Madhya Pradesh, India for treating tuberculosis related symptoms.

ETHNOPHARMACOLOGICAL RELEVANCE: Tuberculosis (TB) is one of the highly infectious disease caused by the bacterium Mycobacterium tuberculosis (Mtb). Several medicinal plants are traditionally used by the tribal healers of some tribal pockets of Madhya Pradesh (M.P.), India in the treatment of various ailments including TB related symptoms. The information of traditional knowledge of plants is empirical lacking systematic scientific investigation. AIM OF THE STUDY: To provide a scientific rationale for the traditional uses of some medicinal plants in treating prolonged cough, chest complaints and TB by ethnic groups in four districts of the state of M.P., India. The anti-mycobacterial activity of these plants was also investigated against multidrug-resistant (MDR) strains of Mtb. The active plant extracts were also assessed for general cytotoxicity by human monocytic leukemia cell line, THP-1 macrophages. MATERIALS AND METHODS: Semi structured interviews and guided field-walk methods were used to gather information on medicinal plants used by the tribal traditional healers. The study was carried out in the tribal pockets of Anuppur, Mandla, Umariya and Dindori districts of M.P., India. A total of 35 plant species distributed in 22 families were selected based on folklore uses suggested by the tribal traditional healer. The ethanol extracts of plants were evaluated for anti-mycobacterial activity against Mtb H37Rv and six MDR clinical isolates of Mtb. The anti-mycobacterial activity of plants was determined in terms of minimum inhibitory concentration (MIC) using standard resazurin microtitre plate assay (REMA). The plant extracts found to be active against Mtb were further evaluated for general cytotoxicity against human THP-1 macrophages using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay. The selectivity index (SI) of active plant extracts were also calculated on the basis of MIC and cytotoxicity. RESULTS: Out of the 35 plants, 11 plant species showed anti-mycobacterial activity with MIC ranging from 500 to 31.25 µg/mL against Mtb H37Rv. The plant extracts also exhibited anti-mycobacterial activity against six multi-drug resistant (MDR) clinical strains of Mtb isolated from sputum samples of pulmonary TB patients. In vitro cytotoxicity of active plant extracts was also assessed in human THP-1 macrophages. The IC50 (50% inhibitory concentration) values of most of the plant extracts on THP-1 was found to be higher than MIC values against Mtb, indicating that the THP-1 cells are not adversely affected at concentrations that are effective against Mtb. Significant anti-mycobacterial activity was observed for eleven plants viz., Alstonia scholaris (L.) R. Br., Glycyrrhiza glabra L., Holorrhena antidysentrica (Roth) Wall. exA.DC., Mallotus philippensis (Lam.) Müll. Arg., Eulophia nuda Lindl., Cocculus hirsutus (L.) Diels, Pueraria tuberosa (Willd.) DC., Cyperus rotundus L., Curcuma caesia Roxb., Sphaeranthus indicus L. and Plumbago zeylanica L. which lends support to their traditional uses. CONCLUSION: The present investigation supports the potential role of plants used by tribal healers as our results have shown that these plants exhibit anti-mycobacterial activity in the acceptable range against Mtb. Our study clearly lends support to the traditional uses of some plants in TB related symptoms as we have found them to exhibit significant in vitro anti-TB activity. To the best of our knowledge, anti-mycobacterial activity in plants against Mtb is being reported for the first time from tribal areas of M.P., India by the current study.

Plants in our combating strategies against Mycobacterium tuberculosis: progress made and obstacles met.

CONTEXT: Traditionally used plants for treating chest-related problems/tuberculosis (TB) have not been evaluated in detail and hence a thorough study is needed in this regard. This knowledge may find application in developing new anti-TB drugs. OBJECTIVE: This article elaborates on studying the activity of medicinal plants against different forms of Mycobacterium tuberculosis (Mtb) using different model strains, in vitro and ex vivo assays for studying the tuberculocidal activity and discusses the results from different studies on the activity against different forms of Mtb and human immunodeficiency virus-tuberculosis (HIV-TB) co-infection. METHODS: Scientific databases such as PubMed, Elsevier, Scopus, Google scholar, were used to retrieve the information from 86 research articles (published from 1994 to 2016) related to the topic of this review. RESULTS: Twenty-three plant species have been reported to possess active molecules against multi-drug resistant (MDR) isolates of Mtb. Seven plants were found to be active against intracellular Mtb and six against dormant bacilli. Seven plants were synergistically effective when combined with anti-TB drugs. Six studies suggest that the beneficial effects of plant extracts are due to their wide array of immuno-modulatory effects manifested by the higher expression of cytokines. Some studies have also shown the dual activity (anti-HIV and anti-TB) of plants. CONCLUSION: We emphasize on identifying plants based on traditional uses and testing their extracts/phytomolecules against MDR strains, intracellular Mtb as well as against dormant Mtb. This will help in future to shorten the current therapeutic regimens for TB and also for treating HIV-TB co-infection.