Shyamapada Mandal

Antibacterial activity of honey against clinical isolates of Escherichia coli,Pseudomonas aeruginosa and Salmonella enterica serovar Typhi

Abstract Objective To ascertain the potential antibacterial activity of honey against clinical isolates of Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Salmonella enterica serovar Typhi (S. enterica serovar Typhi ) by in vitro methods. Methods The partial inhibitory concentration (PIC), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of the autoclaved honey (extracted from Apis indica hive by indigenous method) were determined for S. enterica serovar Typhi ( n =8; from blood cultute), E. coli ( n =5; from urine culture) and P. aeruginosa ( n =5; from pus culture) isolates by in vitro methods. Results The PICs of the honey tested for the isolates ranged 0.50%-1.25 % (v/v) for S. enterica serovar Typhi, 0.75%-1.50% (v/v) for E. coli and 1.00%-1.25 % (v/v) for P. aeruginosa , while the MICs ranged 1.75%–3.00% (v/v), 3.00%-3.50% (v/v) and 3.50% (v/v), respectively. The P. aeruginosa and E. coli isolates had MBC value of 4.00% (v/v); the S. enterica serovar Typhi showed MBCs in between 3.00% and 3.50% (v/v). The bactericidal activity of honey was achieved at concentration 3.00% (v/v) for S. enterica serovar Typhi and E. coli , and at 3.50% (v/v) for P. aeruginosa . Conclusions The excellent antibacterial activity of honey against clinical bacterial isolates indicates the usefulness of honey in clinical practice against bacterial infection.

Synergistic anti–Staphylococcus aureus activity of amoxicillin in combination with Emblica officinalis and Nymphae odorata extracts

To evaluate the antibacterial activity of Emblica officinalis Gaertn (E. officinalis; Family: Euphorbiaceae) seed and Nymphae odorata Aiton (N. odorata; Family: Nymphaeaceae) stamen extracts, alone and in combination, and in combination with amoxicillin (Ax) against Staphylococcus aureus (S. aureus). 1eiliods: Antibacterial activity of ethanolic extracts of amla, E. officinalis, seed (AMS; 500μg) and sapla, N. odorata, stamen (SAP; 500μg) for 12 methicillin-resistant S. aureus (MRSA) isolates was determined following agar diffusion; in order to assess the combined antibacterial activity, AMS (250μg) plus SAP (250μg) were considered. The Ax (10μg) activity alone and in combination with AMS (250μg), and SAP (250μg) was determined by disk diffusion. The zone diameters of inhibition (ZDIs) for the agents were recorded, and growth inhibitory indices (Gus) were calculated. Results: The MRSA isolates (n=12) had AMS (500 p g) and SAP (500μg) ZDIs of 12-19 mm and 21-24 mm, respectively. The ZDIs (range 24-27 mm) increased by 3-4 mm due to combined action of AMS (250μg) and SAP (250μg) indicating synergy between extracts for MRSA (GII 0.634-0.742). The MRSA isolates were resistant to Ax (ZDI: 8-11 mm), which in combination with AMS and SAP had synergistic effect, both due to increased ZDI [mean±SD(3.5±0.577)mm] and GII (0.631-0.894). Conclusions: The data suggest that the plants, E. officinalis and N. odorata alone or in combination, are promising in the development of phytomedicines, which may be used, alone or in combination with the antibiotic, Ax, against MRSA infection.

Enhancing chloramphenicol and trimethoprim in vitro activity by Ocimum sanctum Linn. (Lamiaceae) leaf extract against Salmonella enterica serovar Typhi

OBJECTIVE To evaluate the antibacterial activity of Ocimum sanctum (O. sanctum) leaf extract, alone, and in combination with chloramphenicol (C) and trimethoprim (Tm) against Salmonella enterica serovar Typhi (S. typhi). METHODS The antibacterial activity of ethanolic extract of tulsi, O. sanctum, leaf (TLE; 500 μg) for 23 S. typhi isolates was determined following agar diffusion. The C (30 μg) and Tm (5 μg) activity alone and in combination with TLE (250 μg) was determined by disk diffusion. The zone diameter of inhibition (ZDI) for the agents was recorded, and growth inhibitory indices (GIIs) were calculated. RESULTS The S. typhi isolates (n=23), which were resistant to both C (ZDI 6 mm) and Tm (ZDI 6 mm), had TLE (500 μg) ZDIs 16-24 mm. The ZDIs of C and Tm were increased up to 15-21 mm and 17-23 mm, respectively, when TLE (250 μg) was added to the C and Tm discs. The GIIs ranged 0.789-1.235 and 0.894-1.352, due to combined activity against S. typhi isolates, of C and TLE and Tm and TLE, respectively. CONCLUSIONS The data suggest that TLE, in combination with C and Tm, had synergistic activity for S. typhi isolates, and hence O. sanctum is potential in combating S. typhi drug resistance, as well promising in the development of non-antibiotic drug for S. typhi infection.

Plasmid-Mediated Dimethoate Degradation by Bacillus licheniformis Isolated From a Fresh Water Fish Labeo rohita

The Bacillus licheniformis strain isolated from the intestine of Labeo rohita by an enrichment technique showed capability of utilizing dimethoate as the sole source of carbon. The bacterium rapidly utilized dimethoate beyond 0.6 mg/mL and showed prolific growth in a mineral salts medium containing 0.45 mg/mL dimethoate. The isolated B licheniformis exhibited high level of tolerance of dimethoate (3.5 mg/mL) in nutrient broth, while its cured mutant did not tolerate dimethoate beyond 0.45 mg/mL and it was unable to utilize dimethoate. The wild B licheniformis strain transferred dimethoate degradation property to E coli C600 (Nar, F−) strain. The transconjugant harbored a plasmid of the same molecular size (approximately 54 kb) as that of the donor plasmid; the cured strain was plasmid less. Thus a single plasmid of approximately 54 kb was involved in dimethoate degradation. Genes encoding resistance to antibiotic and heavy metal were also located on the plasmid.

Synergism of Ciprofloxacin and Trimethoprim against Salmonella enterica Serovar typhi Isolates Showing Reduced Susceptibility to Ciprofloxacin

The activity of the combination of ciprofloxacin and trimethoprim against 16 Salmonella enterica serovar typhi isolates from blood cultures were tested by agar dilution checkerboard technique. When used in combination, minimum inhibitory concentrations (MICs) of ciprofloxacin and trimethoprim ranged from 0.5 to 1.25 and from 10 to 125 µg/ml, respectively, and fractional inhibitory concentrations (FICs) from 0.025 to 0.125 and from 2.5 to 10 µg/ml, respectively. The FIC index was 0.140–0.483, indicating a marked synergy between ciprofloxacin and trimethoprim against trimethoprim-resistant S. enterica serovar typhi isolates (100%) with high MICs for ciprofloxacin.

Antibiotic Resistance Prevalence and Pattern in Environmental Bacterial Isolates

The present study investigates the prevalence of antibiotic resistance among bacterial isolates from different environmental samples and determines their resistance patterns. Bacteria were isolated from the Ganges water, the intestine of Labeo rohita, soil samples from agricultural land, and clinical samples of urine, pus, and throat swab. The bacterial isolates were identified on the basis of standard cultural, morphological and biochemical characteristics. Antibiotic susceptibility of the isolates was tested by disc diffusion and agar dilution method. A total of 87 bacteria belonging to 13 different genera were isolated. The percentages of resistance detected were, Ax: amoxycillin (82.75%), Te: tetracycline (49.42%), Tr: trimethoprim (41.37%), Ch: chloramphenicol (39.08%), Nx: nalidixic acid (22.98%), Ci: ciprofloxacin (24.13%), S: streptomycin (9.19%), G: gentamycin (4.59%) and Ak: amikacin (4.59%). A majority of 57 (65.51%) strains were multi-resistant; 77 (88.5%) were resistant to at least one drug. Determination of resistance pattern revealed that 3 water isolates and 1 clinical isolate belonging to Pseudomonas aeruginosa (n=3) and Proteus vulgaris (n=1) were resistant to all the 9 antibiotics tested; a Proteus mirabilis strain was resistant to all the drugs except G. In the seven-drug-resistant group, Klebsiella aerogenes showed AxChTeNxTSCi-resistance and P. mirabilis strain exhibited AxChTeNxTrGCi resistance pattern. The high prevalence of antibiotic-resistant bacteria harboring diverse resistance traits could represent a potential health risk. The study of antibiotic resistance helps predict future emergence and guide the development of strategies to counteract this resistance. Therefore periodic and comprehensive survey of antibiotic resistance in the environmental bacteria is required.

Antibiotic resistance of Salmonella enterica serovar Typhi in Kolkata, India, and in vitro experiments on effect of combined chemotherapy.

This communication states the changing patterns of Salmonella enterica serovar Typhi (S. Typhi) isolates causing enteric fever in and around Kolkata, India. Among the isolates resistance to ampicillin (A), chloramphenicol (C), cotrimoxazole (Co) and tetracycline (T) were plasmid mediated; the plasmid was unstable in S. Typhi, and the other enteric bacteria like Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris were found to be the potential source of dissemination of such plasmids into S. Typhi. The infection with such S. Typhi strains were successfully treated with ciprofloxacin (Cp: MICs 0.0075–0.075 μg mL−1) and/or ofloxacin (Ofx: MICs 0.0125–0.075 μg mL−1), but in the later course, the S. Typhi strains, showing resistance to nalidixic acid, developed low level of resistance to Cp and Ofx, causing the treatment failure. Thus, the treatment regimen was shifted to the third generation cephalosporins like ceftriaxone (Ct) and cefotaxime (Cf). Keeping in mind the anticipation of development of resistance to Ct/Cf, we prepared the treatment regimen for MDR enteric fever, based on the double-drug synergy tests in vitro; Cp-gentamycin (FICI 0.121–0.216) and Cp-trimethoprim (FICI 0.14–0.483) combinations were found effective against S. Typhi isolates having decreased sensitivity to cp (MICs: 0.5–1.25 μg mL−1).

Detection of intestinal colonization of probiotic Lactobacillus rhamnosus by stool culture in modified selective media

Abstract Objective To develop an approach for making a selective and differential media specific for Lactobacillus rhamnosus Goldin and Gorbach (LGG) in order to distinguish it from other bacterial flora in fecal samples. Methods The current media referred as LGGM has been prepared by using MRS media ingredients (replacing dextrose with 2% sorbitol), and incorporation of nalidixic acid (40 μg/mL), bromocresol purple (0.002 %); the pH of the media was adjusted to 4.5. Results The LGGM showed a greater colony forming units compared to MRS media. The growth of pure LGG strain was significantly greater in LGGM, and the recovery rate of LGG released from fecal samples (after oral feeding) was significantly greater (P Conclusions Thus LGGM could be used as a potential media for the isolation and identification of LGG strain.

Indigenous Probiotic Lactobacillus Isolates Presenting Antibiotic like Activity against Human Pathogenic Bacteria

Background: Indigenous lactic acid bacteria are well known probiotics having antibacterial activity against potentially pathogenic bacteria. This study aims to characterize the curd lactobacilli for their probiotic potentiality and antagonistic activity against clinical bacteria. Methods: Four curd samples were processed microbiologically for the isolation of lactic acid bacteria (LAB). The LAB strains obtained were identified by conventional methods: cultural aspect, gram-staining, biochemical and sugar fermentation tests. The probiotic properties were justified with tolerance to low-pH, bile salt and sodium chloride, and the antagonistic activity of the lactobacilli against human pathogenic bacteria (Escherichia coli, Proteus vulgaris, Acinetobacter baumannii and Salmonella enterica serovar Typhi) was assessed. Hemolytic activity and antibiotic susceptibility were determined for the lactobacilli isolates, and the cumulative probiotic potential (CPP) values were recorded. Result: Four lactobacilli isolates, L. animalis LMEM6, L. plantarum LMEM7, L. acidophilus LMEM8 and L. rhamnosus LMEM9, procured from the curd samples, survived in low-pH and high bile salt conditions, and showed growth inhibitory activity against the indicator bacteria by agar-well (zone diameter of inhibition; ZDIs: 13.67 ± 0.58–29.50 ± 2.10 mm) and agar overlay (ZDIs: 11.33 ± 0.58–35.67 ± 2.52 mm) methods; the average growth inhibitory activity of lactobacilli ranged 233.34 ± 45.54–280.56 ± 83.67 AU/mL, against the test bacterial pathogens. All the lactobacilli were non-hemolytic and sensitive to most of the test antibiotics. The CPP values of the isolated LAB were recorded as 80–100%. Conclusion: The curd lactobacilli procured might be used as the valid candidates of probiotics, and bio-therapeutics against bacterial infection to humans.

Antibacterial Potential of Neem Tree ( Azadirachta indica A. Juss) Seeds

Publisher Summary This chapter examines the nutritional content of neem tree seeds. In recent years, interest in neem has focused on its repellent, anti-feedant, and growth-disrupting effects on insects, as well as its ability to provide a cheap natural pesticide. Neem oil, produced from the seed kernels of neem fruit, is the most commonly used neem product. It is generally regarded as possessing the highest concentration of active components with regard to the manufacture of pesticides. Neem is a very important traditional medicinal plant in India that has been used extensively in Ayurveda, Unani, and homeopathic medicine and has become a focus of modern medicine. The consensus is that the general antimicrobial activity of neem extracts is mainly due to azadirachtin. Nimbidin, a crude bitter principle extracted from neem seed oil, has demonstrated several biological activities; in vitro, it can completely inhibit the growth of Mycobacterium tuberculosis and has also been found to be bactericidal. Neem seed extracts are bactericidal against gram-negative as well as gram-positive pathogens, and thus have broad spectrum activity; they also have a synergistic interaction in combination with antibiotics. Although crude extracts from various parts of neem have been used for medicinal applications since time immemorial, modern drugs can be developed after extensive investigation of its pharmacotherapeutics and toxicity, as well as proper standardization.