| Literature DB >> 30167378 |
Zeinab I Sadek1, Mohamed A Abdel-Rahman2, Mohamed S Azab2, Osama M Darwesh3, Mahmoud S Hassan2.
Abstract
A 205 samples representing eight different infant foods with various based materials were collected and analyzed for their microbiological properties. The contamination rate by aerobic spore formers was achieved 100% in milk based infant food with fruit, vegetables, honey, rice and infant milk powder. While, it was detected in 95, 60 and 65% of the infant food with wheat milk based, ready to use (infant food with fruit) and ready to use (infant food with vegetables), respectively. Biochemical Identification and API 50 CHB used to identify the obtained isolates and revealed that B. subtilis was the most frequently occurring Bacillus spp. Followed by B. licheniformis and B. circulans. While B. cereus was detected in 10.20% of the total isolates. Moreover, B. cereus was confirmed in 21.2% of milk based fruit, vegetables (15.7%), honey (17.2%), rice (14.1%) and wheat (12%) and vanished in the infant milk powder samples. Although, B. cereus noted in lower percentage but this strain is considered as the more harmful one in lower numbers. For that, the following part is focused on B. cereus. Forty five isolates obtained from B. Cereus contaminating samples were screened for prevalence of 3 important virulent enterotoxigenic genes using PCR technique. The CYTK gene had the highest presence which detected in 43 isolates (95.5%), followed by NHEC gene detected in 32 isolates. However, the HBLA gene was detected in just 5 isolates. So, many processes should be applied for controlling of pathogens to preserve infant lives.Entities:
Keywords: Bacillus spp.; Enterotoxigenic genes; Infant foods; Molecular detection
Year: 2018 PMID: 30167378 PMCID: PMC6111046 DOI: 10.1016/j.toxrep.2018.08.013
Source DB: PubMed Journal: Toxicol Rep ISSN: 2214-7500
The primer sequences and amplicon sizes used in PCR analysis.
| Gene | Primer sequences (50–30) | Amplicon size (bp) | Reference |
|---|---|---|---|
| hblA | F-5׳ AAGCAATGGAATACAATGGG 3׳ | 1154 | Minnaard et al. [ |
| nheC | F-5׳ CGGTAGTGATTGCTGGG 3׳ | 581 | [ |
| cytK | F-5׳ CGACGTCACAAGTTGTAACA 3׳ | 565 | [ |
Total bacteria, total aerobic spore forming, total psychrotrophic spore forming, and total Bacillus cereus group counts in tested samples.
| Type of tested samples | Number | Bacterial groups* | Positive samples | Counts (log10cfu/g) | ||
|---|---|---|---|---|---|---|
| No % | Min. | Max. | Mean. | |||
| infant food with fruit milk based | 45 | 1 | 45(100) | 2.593 | 4.161 | 3.453 |
| 2 | 45(100) | 2.159 | 3.807 | 3.167 | ||
| 3 | 27(60) | 0 | 2.608 | 0.987 | ||
| 4 | 28(62.2) | 0 | 2.820 | 1.497 | ||
| infant food with vegetables milk based | 15 | 1 | 15(100) | 2.441 | 4.275 | 3.365 |
| 2 | 15(100) | 1.441 | 3.945 | 2.840 | ||
| 3 | 6(40) | 0 | 1.852 | 0.583 | ||
| 4 | 4(26.6) | 0 | 2.800 | 0.652 | ||
| infant food with honey milk based | 20 | 1 | 20(100) | 1.759 | 3.849 | 3.070 |
| 2 | 20(100) | 1.492 | 3.621 | 2.840 | ||
| 3 | 1(5) | 0 | 2.075 | 0.104 | ||
| 4 | 6(30) | 0 | 2.651 | 0.679 | ||
| infant food with rice milk based | 20 | 1 | 20(100) | 1.259 | 3.761 | 2.923 |
| 2 | 20(100) | 1.159 | 3.495 | 2.619 | ||
| 3 | 2(10) | 0 | 1.100 | 0.101 | ||
| 4 | 3(15) | 0 | 2.593 | 0.358 | ||
| infant food with wheat milk based | 20 | 1 | 20(100) | 1.833 | 3.819 | 2.856 |
| 2 | 19(95) | 0 | 3.394 | 2.410 | ||
| 3 | 2(10) | 0 | 1.100 | 0.082 | ||
| 4 | 4(20) | 0 | 2.360 | 0.451 | ||
| infant milk powder | 45 | 1 | 45(100) | 1.651 | 3.416 | 2.417 |
| 2 | 45(100) | 1.159 | 3.030 | 2.129 | ||
| 3 | -ve | -ve | -ve | -ve | ||
| 4 | -ve | -ve | -ve | -ve | ||
| ready to use (infant food with fruit) | 20 | 1 | 18(90) | 0 | 2.388 | 1.896 |
| 2 | 12(60) | 0 | 2.160 | 1.208 | ||
| 3 | -ve | -ve | -ve | -ve | ||
| 4 | -ve | -ve | -ve | -ve | ||
| ready to use (infant food with vegetables) | 20 | 1 | 20(100) | 1.360 | 2.463 | 1.982 |
| 2 | 13(65) | 0 | 2.229 | 1.199 | ||
| 3 | -ve | -ve | -ve | -ve | ||
| 4 | -ve | -ve | -ve | -ve | ||
Where, 1; Total bacterial counts, 2; Total aerobic spore forming counts, 3; Total psychrotrophic spore forming counts, 4; Total Bacillus cereus group counts.
Fig. 1Distribution of different total Bacillus species from total isolates.
Where, A; infant food with fruit milk based, B; infant food with vegetables milk based, C; infant food with honey milk based, D; infant food with rice milk based, E; infant food with wheat milk based, F; infant milk powder, G; ready to use (infant food with fruit), H; ready to use (infant food with vegetables), 1; B. subtilis, 2; B. cereus, 3; B. licheniformis, 4; B. coagulans, 5; B. circulans, 6; B. pumilus, 7; B. firmus, 8; B. smithii, 9; None Bacillus.
Where, 1; B. subtilis, 2; B. cereus, 3; B. licheniformis, 4; B. coagulans, 5; B. circulans, 6; B.pumilus, 7; B. firmus, 8; B. smithii, 9; None Bacillus.
Fig. 2Distribution of different total Bacillus species in tested samples.
Prevalence of enterotoxin genes of 45 B. cereus isolates.
| NO. | Samples | No. of | Hemolytic BL complex | Non-hemolytic enterotoxin complex | cytotoxic gene |
|---|---|---|---|---|---|
| 1 | infant food with fruit milk based | 28 | 2(7.1) | 21(75) | 27(96.4) |
| 2 | infant food with vegetables milk based | 4 | 1(25) | 3(75) | 3(75) |
| 3 | infant food with honey milk based | 6 | 0 | 5(83.3) | 6(100) |
| 4 | infant food with rice milk based | 3 | 0 | 0 | 3(100) |
| 5 | infant food with wheat milk based | 4 | 2(50) | 3(75) | 4(100) |
| Total | 45 | 5(11.1) | 32(71.1) | 43(95.5) | |
Fig. 3Agarose gel image for the PCR product of hblA gene in B. cereus isolates compared with marker (1 kb); Numbers on image related to positive detected isolates only.
Fig. 4Agarose gel image for the PCR product of nheC gene in B. cereus isolates compared with marker (1 kb); Numbers on image related to positive detected isolates only.
Fig. 5Agarose gel image for the PCR product of cytK gene in B. cereus isolates compared with marker (1 kb); Numbers on image related to positive detected isolates only.
Hemolytic activity of the isolated B. cereus.
| Type of infant food samples | No. of isolates | Positive isolates | |
|---|---|---|---|
| No. | % | ||
| Fruit milk based | 35 | 34 | 97.1 |
| Vegetables milk based | 9 | 9 | 100 |
| Honey milk based | 14 | 14 | 100 |
| Rice milk based | 11 | 11 | 100 |
| Wheat milk based | 9 | 8 | 88.8 |
| Total | 78 | 76 | 97.4 |