A total 940 samples (both fruits and vegetables) were collected from supermarket in and aroundKalaburagi (Karnataka, India) of which 390 were (23.84%) fruits of different verities and 550 (35.27%) were mixture of different types of vegetables. Among 390 fruitsand 550 vegetable samples, 93 (23.84%) and 194 (35.27%) were showed cultural positivity for the pathogenic bacteria respectively (Table 1). The number of isolated microbial colonies from different fruits and vegetables were represented in (Table 1) and (Fig 1 and 2).
Further, out of 93 positive samples, it is identified that 36.56% (34 out of 93) of
Salmonella spp., 7.53% (7 out of 93) of
Shigella spp.
and 55.91% (52 out of 93) of
E.
coli were isolated from fruit samples. Similarly, 35.60% of
Salmonella spp., 25.26% of
Shigella spp.
and 38.14%
E.
coli was isolated from vegetable samples (Table 1). This clearly indicates that high level of pathogenic bacteria contamination found in food samples.Among the three pathogenic bacteria, the
E.
coli was found to be more prevalent (13.49%) when compared to that of
Salmonella(11.24%) and
Shigella (5.99%)in the present study.
The antibiotic sensitivity for the three bacterial isolates was assessed using different antibiotics. High resistance for
E.
coli spp.
Salmonella spp. and
Shigella spp. to nalidixic acid (86.50%), ciprofloxacin (86.66%) and vancomycin (80.35%) was observed respectively . However, respond
E.
coli,
Salmonella and
Shigella spp., showed a resistance to different antibiotics at different percentage level (Table 2, 3) and( Fig 3a and b).
We further evaluated the MIC valuesfor
E.
coli,
Salmonella and
Shigella isolates. Among the three isolates,
E.
coli has shown highestMIC value to gentamicin (4-16μg/ml). Astonishingly,
Salmonella has the higher MIC value toceftriaxone (8-64μg/ml) andimipenem,(4-16μg/ml). Similarly,
Shigella isolates were shownhighest toampicillin (8-32μg/ml) and nalidixic acid (13-32 μg/ml),when compare to that of other antibiotics (Table 4).
This study provides clear evidence of contamination of fresh Fruits and vegetables from common food-borne pathogens including
E.
coli,
Salmonella and
Shigella spp
are important food-borne pathogen and its prevalence in fresh food poses a threat to human. The increase in demand and consumption of fruits and vegetables has resulted in a rise in food-borne related illnesses and outbreaks. Fresh fruits and vegetable have been reported to anchor potential food-borne pathogens including
E.
coli,
Salmonella and Shigella spp.,
(Mallikarjun and Gundappa, 2016; Harris et al., 2003; CDC, 2009).
E.
coli has showed (54.55%) to Nalidixic acid, similar Ampicillin and gentamicin (36.36 %,) Amoxicillin and ciprofloxacin were only (9.09%) [29],
Salmonella Showed (42%) to Ampicillin and
Shigella (79%)
(Biniam and Mogessie, 2010). The previous study was conducted on microbiological contamination in the Dhaka metropolis Bangladesh mainly for
E.
coli. it was observed that the % of ABR for trimethoprim-sulfamethoxazole combination as (46.03%) compared to the past results of % ABR for same combination on
E.
coli. Similarly, it was found a steep decline in % of ABR for amoxicillin from (46.2%) (past research) to (35.71%) (as per our results) similarly, indicating rise in microbial resistance to this antibiotic. However, there is a ‘steep rise’ in % of ABR for antibiotics such as impenem (from 0% to 19.84%), gentamicin (from 0% to 32.53%) and ceftriaxone (from 0% to 69.04%) confirmed by these results. Therefore, our results indicating that the microbe
i.
e. E coli have acquired ‘less antibiotic resistance to the above series of antibiotics’
(Khatib et al., 2015).
A number of surveys have attempted to detect
E.
coli O157:H7 in fresh fruits and vegetables, in a study that included 3,200 vegetables, no O157:H7 positive sample was detected and in another survey of 890 fruits and vegetables, this pathogen could not be found either
(Johannessen et al., 2000). Salmonella resistance against ampicillin (55.5%-31.4%), gentamicin (0%-%), ciprofloxacin (6.5%-13.7%), vancomycin (100%-100%), trimethoprim-sulfamethoxazole (51%-51%), chloramphenicol (3.2%-0%) and nalidixic acid (0%-5.9%), against isolates from cabbage and spinach respectively
(Isoken, 2015).
Salmonellaspp., showed resistance against ampicillin (100%), gentamicin (0%), ciprofloxacin (50%), trimethoprim-sulfamethoxazole (6.3%), Amoxycillin (81.3%), chloramphenicol (6.3%) and nalidixic acid (12.5%)
(Najwa et al., 2015). E.
coli,
Salmonella and
Shigella spp., showed resistance against, gentamicin (60%), ciprofloxacin (0%), Norfloxacin (10%), amoxicillin (70%), chloramphenicol (30%),
Salmonella gentamicin (7.7%), ciprofloxacin (0%), Norfloxacin (0%), amoxicillin (77%), chloramphenicol (92.3%) and
Shigella showed resistance against gentamicin (0%), ciprofloxacin (0%), Norfloxacin (0%), amoxicillin (30%), chloramphenicol (0%),
(Poonam, 2013).
E.
coli,
Salmonella and
Shigella spp., showed resistance against ampicillin (25%), ceftriaxone (67%), ciprofloxacin (60%), trimethoprim-sulfamethoxazole (20%), piperacillin (30%), amoxicillin (33%), chloramphenicol (45%), nalidixic acid (85%),
Salmonella ampicillin (100%), gentamicin (0%), ceftriaxone (0%), ciprofloxacin (100%), trimethoprim-sulfamethoxazole(0%), amoxicillin (0%), chloramphenicol (0%), nalidixic acid (0%),
Shigella ampicillin (100%), gentamicin (0%), ceftriaxone (0%), ciprofloxacin (0%), vancomycin (100%),trimethoprim-sulfamethoxazole (0%),amoxicillin (0%), chloramphenicol (100%), nalidixic acid (100%),
(Nour et al., 2013). E.
coli has been used as the reference indicator for faecal contamination and a number of surveys have reported its isolation from fresh fruits and vegetables
(Jay, 2000). However, in the present study
E.
coli was found in (26.8%) of conventional fresh vegetables in Lebanon, this result is consistent with the prevalence of (25%) this bacterium in ready-to-use lettuce
(Soriano et al., 2000).
The previous microbiological studies have illustrated to evaluate microbiological safety in various regions of Vidarbha through various ‘antibiotic-microbial assays’. In the present study, it is been analyzed and compared antibiotic resistance (ABR) property in microbes such as ‘
E .
coli,
Salmonella and
Shigella’ using several antibiotics. It was found that the antibiotic resistance of
E.
coli to norfloxacin is almost (36.5%) when compared to the past studies performed by others for studying same antibiotic resistance using same norfloxacin, where it was observed that only(10% )of antibiotic resistance in
E coli. Similarly, previous reportshave got high antibiotic resistance for amoxicillin (70%)but it was observed the ‘antibiotic resistance for same amoxicillin’ lesser % of resistance (35.71%). Similarly, the other researchers have observed antibiotic resistance using gentamicin (60%)but we found lesser % of resistance (32.53%), where it was observeda huge variation in this antibiotic-resistance property for gentamicin. However, it was nearly ABR for chloromphenicol is (23.80%) that slightly lesser than other researcher’s result for ABR, where other reportsgot (30%) whereas in present studyABR value (53.93%) forciprofloxacin compared to the past research results for same antibiotic, where ABR value was (0%). Here, it was clearly observedmore ABR for ciprofloxacin compared to the past results
(Soriano et al., 2000).
It was observed ABR for norfloxacin on
Shigella spp., approx. (26.78%) compared tothe past results by other researchers where it was observed only 0% of ABR on same species for same antibiotic. Similarly, we have observed lesser percentageof ABR for amoxicillin approx. (3.57%) when compared tothe past researcher’s result of ABR, which is nearly (70%) on same
Shigella species. There is a huge variation in ABR results that could be due to the microbial ability to acquire resistance to amoxicillin antibiotic.It was found that the percentage of ABR for gentamicin increased from 0% (as per past research) to (3.57%) (as per our results) whereas the percentage of ABR is nearly same and unchanged (0% for both past and our present work) for chromamphenicol on same
Shigella species. However, there is a ‘steep rise’ in percentage of ABR for ciprofloxacin from percentage (as per past research) to (17.85%) (as per results)
(Soriano et al., 2000).
We have significantly observed that the percentage of ABR for norfloxacin on
Salmonella spp. steeply ‘reduced’ from 30.8% (past research) to (4.76%) (as per our results) whereas the percentage of ABR for ciprofloxacin steeply ‘increased’ from percentage (past research) to (44.76%) as per our results. Similarly, it is clearly observed with our results that the % of ABR for amoxicillin is (3.80%), where past researchers have got (69.2%) indicating ‘high microbial resistance’ to this antibiotic. In the meanwhile, the percentage of ABR results for gentamicin is (9.52%) whereas the past research has illustrated that the percentage ABR for same antibiotic is (84.6%). It was observed that percentage ABR for chloromphenicol on
Salmonella spp. (79.40%) indicating a steep decline in ABR compared to the past results (92.3%). Therefore, the microbial resistance patterns for this species on these antibiotics are quiet variable
(Soriano et al., 2000; Poonam, 2013).
The present study provided valuable information regarding pathogenic bacteria species such as,
E.
coli,
Salmonella and
Shigella contamination of fruits or vegetables collected from various markets in Kalaburagi region. This data can facilitate the effective assessment of risk of contamination by
E.
coli,
Salmonella and
Shigella spp., in consumable non-processed fruits or vegetables in Kalaburagiregion suggesting potential public health hazard.