A variety of foods and environmental sources harbor bacteria that are resistant to one or more antimicrobial drugs used in medicine and agriculture. Antibiotic resistance in Escherichia coli is of particular concern because it is the most common Gram-negative pathogen in humans. Hence this study was conducted to determine the antibiotic sensitivity pattern of E. coli isolated from different types of food items collected randomly from twelve localities of Hyderabad, India. A total of 150 samples comprising; vegetable salad, raw egg-surface, raw chicken, unpasteurized milk, and raw meat were processed microbiologically to isolate E. coli and to study their antibiotic susceptibility pattern by the Kirby-Bauer method. The highest percentages of drug resistance in isolates of E. coli were detected from raw chicken (23.3%) followed by vegetable salad (20%), raw meat (13.3%), raw egg-surface (10%) and unpasteurized milk (6.7%). The overall incidence of drug resistant E. coli was 14.7%. A total of six (4%) Extended Spectrum β-Lactamase (ESBL) producers were detected, two each from vegetable salads and raw chicken, and one each from raw egg-surface and raw meat. Multidrug resistant strains of E. coli are a matter of concern as resistance genes are easily transferable to other strains. Pathogen cycling through food is very common and might pose a potential health risk to the consumer. Therefore, in order to avoid this, good hygienic practices are necessary in the abattoirs to prevent contamination of cattle and poultry products with intestinal content as well as forbidding the use of untreated sewage in irrigating vegetables.

Extended-spectrum β-lactamase (ESBL)-producing bacteria pose a big challenge in clinical practices, warranting a new therapeutic strategy. In this study, methanol extract of the marine cyanobacterium Oscillatoria acuminata NTAPC05 was fractionated under bioassay guidance and the fractions were tested against three well-characterized ESBL-producing bacteria Escherichia coli U655, Stenotrophomonas maltophilia B929 and Enterobacter asburiae B938. Out of the four HPLC fractions, fraction 2 showed bactericidal activity against all the three ESBL producers much more efficiently (MIC 100 μg ml) than the fourth-generation cephalosporin (MIC >125 μg ml). The active fraction was subjected to time-kill test at concentrations of 1/2 × MIC, 1 × MIC and 2 × MIC, and the results substantiated the bactericidal property of the fraction against the ESBL producers. Spectral analysis revealed monogalactosyldiacylglycerol containing a palmitoyl (MGDG-palmitoyl), being reported for the first time, as the active fraction, and its bactericidal property against ESBL producers was determined. The active fraction appears to damage the bacterial membrane leading to lysis of the cell, as revealed in confocal laser scanning microscopy (CLSM) analysis, that was confirmed in scanning electron microscopic analysis. Cytotoxicity assay revealed the O. acuminata compound to be safe to a normal cell line HEK293 (human embryonic kidney cell). The in silico analysis of MGDG-palmitoyl revealed two successive H-bonding interactions with Leu198 of TEM1 β-lactamase. Taken together, the MGDG-palmitoyl from O. acuminata NTAPC05 offers potential to develop analogs as a therapeutic for bacteremia caused by ESBL producers.