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Carbapenems are beta (β)-lactam antibiotics active against wide range of bacteria. Carbapenem resistance may be outcome of efflux pump activation, alteration in protein binding proteins, production of carbapenemases which degrade carbapenems. There are number of bacteria producing different types of carbapenemases like NDM (Enterobacteriaceae), IMP (Pseudomonas aeruginosa), IMI (Enterobacter cloacae), KPC (Klebsiella pneumonia), OXA-23, OXA-24/40, OXA-58-type (Acinetobacter baumannii), VIM (Acinetobacter baumannii) etc. Carbapenem resistance is emerging throughout the world due to interspecies transfer of genetic elements carrying genes for carbapenemase production. It is very difficult to control spread of resistant strains because of the continuous threshold of selection present in forms of presence of carbapenems in environment created through wide spread clinical use. To control infection of carbapenem resistant bacteria there are limited options available for treatment. Many a time carbapenem resistant bacteria show pan-resistance and such bacterial infection become life-threatening and cannot be treated with available last resort antibiotics like polymin B, tigecyclin and colistin. Infection of carbapenem resistant bacteria can be controlled using two or more antibiotics or antibiotic+ herbal drug combination or herbal drugs like (carvacrol, cinnamon, holy-basil oil, lemon grass oil) etc. The herbal drugs may be used as first line of treatment against carbapenem resistant bacteria instead of antibiotics. But, how? It is still not very lucid. Besides it, probiotics and homeopathic therapy has also been recommended with no sufficient data to establish their efficacy.

Background: Fungal infections are often difficult to cure in animals due to cost of treatment and emerging antifungal drug resistance. Herbal antifungals may be an alternate. Therefore, the objective of this study was to determine antifungal drug sensitivity pattern and activity of herbal antimicrobials on fungal isolates from clinical cases in animals and their associated environment. Methods and Findings:This study was conducted on 69 isolates comprised of yeasts (49) and moulds (20) isolated from clinical cases of animal (26) and environmental (22) samples and one reference strain for determining antifungal efficacy of common antimycotic drugs (amphotericin B, miconazole, nystatin, clotrimazole, itraconazole, ketconazole and fluconazole) and herbal antimicrobials viz., ajowan (Trachyspermum ammi) seed oil, betel (Piper betle) leaf oil, guggul (Commiphora mukul) oil, thyme (Thymus vulgaris) oil, marjoram (Origanum majorana) essential oil, Cinnamon (Cinnamomum verum) bark oil, holy basil (Ocimum sanctum) oil, citral, cinnamledehyde, carvacrol, lemongrass (Cymbopogon citrates) oil, sandalwood (Santalum album) oil, methanolic extract of Eupatorium odoratum leaves, Methanolic extract of Ageratum conizoides, essential oil of Zanthoxyllum rhetsa seed carp, agarwood (Aquilaria malaccensis) oil, and patchouli (Pogostemon cablin) essential oil amphotericin B (100 units), miconazole (10 µg), nystatin (100 units), clotrimazole (10 µg), itraconazole (10 µg), ketconazole (30 µg) and fluconazole (10 µg). Most of the yeast isolates except six from soil (2) and water (4) were sensitive to nystatin. Amphotericin B inhibited almost two third of the yeast isolates and miconazole was the most effective (75%) imidazoles followed by clotrimazole (38.8%), itraconazole (32.65%), fluconazole (18.4%) and ketoconazole (12.25%). Among herbals, thyme oil, carvacrol, cinnamon oil and cinnamaledehyde inhibited the growth of all the yeast isolates tested with MIC ranging from 0.001 mg to 1.2 mg mL -1 . The next most effective herbal was holy basil oil (95.2%) followed by ajowan oil (87.75%), citral (87.75%) and lemongrass oil (77.75%). Lemongrass oil was equally antimycotic both on yeasts and moulds. The study revealed the promising antimycotic activity of herbs and prevalent antimycotic drug resistance among clinically important fungi in animals. Conclusion:The fungi associated with animal clinical infections and their environment were often resistant to commonly used antifungal drugs but some of the herbals as cinnamon oil, thyme oil, ajowan oil and lemongrass oil as well as their active components have shown potential antifungal activity and hope for the future drug development.

Study on citronella essential oil (CEO) sensitivity of 217 microbial strains of 65 species, isolated from animals with different disease conditions, revealed that citronella oil inhibited growth of only 10.6% strains. CEO inhibited Candida but of no Aspergillus strain. CEO inhibited 22 of 211 bacterial strains. Ampicillin was the least effective antibiotic but inhibited 41.2% bacterial strains. Gram positive bacteria (GPBs) were 4.5 more sensitive (p, 0.0006) to CEO than Gram negative bacteria (GNBs). More GNB strains (p, 0.02) were multi-drug resistant (MDR) type than GPB strains. Probability of CEO resistant was high in MDR strains (p, 0.006). Most of the Brucella abortus strains had MDR (83.3%). Strains of swamp buffalo origin were more (p, 0.08) commonly CEO (96.6%) resistant than strains of dog (81.3%) origin. MDR was the maximum in abortion associated (51.2%) strains and minimum in diarrhoea associated strains (25%). The study indicated that CEO is not an effective antimicrobial against veterinary clinical isolates. Antimicrobial drug resistance and CEO resistance patterns of bacteria were dependent on type of pathogen, its source and association with disease in animals and may be important for deciding an effective antimicrobial therapy.

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