Methanolic extract of Hemidesmus indicus root augments the antibacterial and antibiofilm activity of amoxicillin and clindamycin against methicillin-resistant Staphylococcus aureus of bovine origin.

The present study evaluated the antibacterial and antibiofilm activity of methanolic extract of Hemidesmus indicus root (MHIR) in combination with amoxicillin and clindamycin against biofilm-forming methicillin-resistant Staphylococcus aureus (MRSA) isolated from milk samples of mastitic cows. Microdilution susceptibility testing and microtitre plate assays were used to evaluate the in vitro efficacy of MHIR and antibiotic combinations against MRSA (n = 12). Furthermore, in vitro findings were validated in a murine model. Minimum inhibitory concentration and minimum biofilm inhibitory concentration of amoxicillin and clindamycin in combination with MHIR were significantly (P < 0·05) lower than when used alone against MRSA. In terms of antibacterial activity, MHIR showed additive interaction (fractional inhibitory concentrationindex >0·5-4) with amoxicillin and clindamycin against all the MRSA isolates, whereas MHIR synergizes (fractional biofilm inhibitory concentrationindex ≤0·5) the antibiofilm activity of amoxicillin and clindamycin against 58·33% and 83·33% of the MRSA isolates respectively. Amoxicillin/clindamycin in combination with MHIR significantly (P < 0·05) reduced disease activity score, and bacterial load and Gram-positive spots in kidney and liver of MRSA-infected mice. The combined efficacy of MHIR and amoxicillin/clindamycin was comparable to clindamycin alone but superior to amoxicillin alone. Hence, the combination of MHIR with amoxicillin/clindamycin is advocated in the treatment of MRSA-associated infections.

Isolation and characterization of bacteriophages with lytic activity against common bacterial pathogens.

AIM: Present investigation was conducted to isolate and characterize bacteriophages with lytic activity against common bacterial pathogens. MATERIALS AND METHODS: A total of 60 samples of animal waste disposal from cattle (42) and buffalo (18) farms were collected from three different strata, i.e., top, mid, and bottom of collection tank. Samples were primarily subjected to rapid detection methods, and then isolation of phage was done by double agar layer method using Bacillus subtilis (BsH) and Escherichia coli (EH) as host system. Phages were characterized on the basis of plaque morphology, temperature, pH susceptibility, and host range. RESULTS: Recovery of phages was higher from dairy cattle farm waste (78.57%) as compared to buffalo farm waste (72.22%) and bottom layer of tank showed maximum recovery. Bacillus subtilis (91%) supported the growth of more phages as compared to E. coli (9%). Three different phage morphotypes were observed each against Bacillus subtilis (BsHR1, BsHR2, and BsHR3) and E. coli (EHR1, EHR2, and EHR3). Mean phage titer of above six phage isolates ranged between 3×1010 and 5×1012 plaque forming units/ml. Viability of phages was by, and large unaffected at 70°C within 2-3 min, and phage isolates were completely inactivated below pH 3 and above 11. Coliphage EHR1 had widest host range followed by BsHR1 and BsHR2 while EHR2, EHR3, and BsHR3 had low lytic activity. CONCLUSION: It could be concluded from the present study that the Bacillus and Coli phage has wide host range and thus exhibits the potential to be used as drug substitute tool against common bacterial pathogens.

Comparative study on immunoglobulin Y transfer from breeding hens to egg yolk and progeny chicks in different breeds of poultry.

AIM: This study was undertaken to compare the immunoglobulin Y (IgY) level and its efficacy in laying hens of four different breeds of poultry (viz., Vanraja, Gramapriya, BlackRock, and KalingaBrown) and its relative transfer in egg yolk and chick. MATERIALS AND METHODS: This study was conducted in 48 apparently healthy laying hens vaccinated with Salmonella inactivated polyvalent vaccine, eggs and progeny chicks; 12 each from four different breeds of poultry, viz., Vanraja, Gramapriya, BlackRock, and KalingaBrown. The methodology included measurement of egg and yolk weight, total protein and IgY in egg yolk, total serum protein and IgY in breeding hens, and progeny chicks and extent of IgY transfer from hens to yolk then to chicks. Further, Salmonella-specific antibodies in breeding hens, egg yolk and progeny chicks were assessed using O and H antigen by tube agglutination test. RESULTS: The egg weight differed nonsignificantly (p>0.05) among breeds, however, breed wise significant variation (p<0.01) was reported in yolk weight. The weight of egg yolk significantly affects the total protein and IgY concentration although these levels per unit of volume did not differ. Total protein was significantly higher (p<0.01) in KalingaBrown and Gramapriya as compared to Vanraja and BlackRock. Non-significant (p>0.05) difference among breed was found in total protein of egg yolk and chick. The IgY concentration in hens, egg yolk and chick was found to be in the range of 5.35±0.63-5.83±0.65, 2.3±0.1-2.6±0.2, and 1.3±0.11-1.7±0.16 mg/ml, respectively which is uniform and independent of total protein concentration at all the three levels. Significant breed variations were not observed in maternal IgY transfer from breeding hens to chicks and were 25.62±1.42-36.06±4.34% of total IgY in parent flock. Moderate to higher rate of seroprevalence with peak titers of 1:640 against Salmonella-specific antibodies was observed in only 41.6% of breeding hens. CONCLUSION: No significant difference in the rate of transfer of IgY was observed in four breeds studied (viz., Vanraja, Gramapriya, BlackRock, and KalingaBrown) and moderate seropositivity was detected for Salmonella-specific antibodies in progeny chicks.