Identification of Coxiella burnetii by touch-down PCR assay in unpasteurized milk and dairy products in north - east of Iran

Coxiella burnetii is the causative agent of the zoonotic disease Q fever, and ruminants being considered as the main source for human infection. Although the main route of infection in human is inhalation of contaminated aerosols, oral transmission by contaminated raw milk or unpasteurized dairy products is also a possible route of infection. Raw milk or dairy products produced from unpasteurized milk may contain virulent C. burnetii. This study aimed to determine the contamination rate of milk and unpasteurized dairy products with C. burnetii. Touch-down PCR was used to examine the presence of C. burnetii on 147 dairy product samples collected from local traditional and commercial markets in Mashhad-Khorasan Razavi province- Iran. 2 of 28 [7.14%] cheese samples, 2 of 26 [7.69%] yoghurt samples, 8 of 23 [34.78%] sheep milk samples, and 2 of 60 [3.33%] cow milk samples were found to be positive for C. burnetii DNA. However, 10 goat milk samples were found to be negative. The results of this study indicate that the clinically healthy dairy livestock and their dairy products are important sources of C. burnetii infection

Intestinal colonization of different Brachyspira spp. in laying hens

Avian intestinal spirochetosis [AIS] is caused by spiral-shaped Gram-negative Brachyspira spp. in poultry. It is known as a cause of diarrhea, low egg production, and increased occurrence of dirty eggs in layer hens. In this study, the presence of some Brachyspira spp. was investigated in laying hens. A total of 100 cloacal swab samples were individually collected from 20 laying hen flocks showing fecal egg staining in northeast of Iran. Using culture and morphologic examination, 41 samples [41%] from 20 flocks were positive; however, by using genus-specific PCR, only 37 [37%] samples were confirmed as Brachyspira spp. Using species-specific primers, single colonization was identified in 18 samples associated with B. pilosicoli [48.6%], while single colonization with B. intermedia was found in only two samples [5.4%]. Simultaneous colonization by B. intermedia and B. murdochii was detected in 3 samples [8.1%]. B. pilosicoli was the most prevalent species in concurrent colonization in 11 cases [29.7%]. Finally, cocolonization by B. intermedia and B. innocens was identified in 3 samples [8.1%]. The results of this study showed the colonization of different species of Brachyspira with dominance of B. pilosicoli in layer hens

Modeling the effects of Bunium persicum [Black Zira] essential oil, pH, inoculums size and temperature on the growth of Listeria monocytogenes

Listeriosis is acknowledged as a major foodborne disease throughout the world caused by Listeria monocytogenes. Different factors can affect the growth of food borne microbial pathogens. The aim of this study was to investigate the combined effects of different concentrations of Bunium persicum essential oil [EO] [0%, 0.08%, 0.16%, 0.24%], three incubation temperatures [35ºC, 25ºC, 4ºC], three levels of pH [5, 6, 7] and two inoculum sizes [103 and 105 cfu ml-1] on the growth of Listeria monocytogenes in brain heart infusion [BHI] broth. To evaluate effects of explanatory variable on time to detection [TTD] of bacterial growth, parametric survival models based on the log normal distribution were used. All explanatory variables had significant association with TTD [P<0.05]. The final model accurately predicted the growth initiation and inhibition of L. monocytogenes. Key words: Listeria monocytogenes, Black Zira essential oil, Time to detection, Modeling

PCR-based detection of cow and goat milk in sheep milk and dairy products marketed in Mashhad city of Iran

The extensive consumption of milk and dairy products makes these foodstuffs targets for potential adulteration with financial gains for unscrupulous producers. The aim of this study was using PCR assay to detect cow milk in labeled sheep milk, sheep yoghurt, and Lighvan cheese [a traditional ripened cheese produced from sheep's milk]. The assay utilized primers targeting the mitochondrial 12s and 16s rRNA gene. In this study, 35 samples of sheep milk, 35 samples of sheep yoghurt, and 35 samples of Lighvan cheese were purchased from different supermarkets in Mashhad city with different batch numbers. The results showed only 21 out of 105 [20%] samples contained pure sheep milk. Undeclared presence of cow and goat milk was detected in 33[31.5%] and 68[65%] of the 105 samples, respectively. It seems the PCR based analytical method is an applicable technique to monitor adulteration in dairy products

presence of Listeria monocytogenes in raw milk samples in Mashhad, Iran

The purpose of this preliminary study was to determine the prevalence of raw milk contamination with Listeria monocytogenes. In this study, 100 bulk tank milk samples were collected randomly and delivered to Pegah Pasteurization Factory in Mashhad. For isolation and identification of L. monocytogenes, the samples were first enriched using cold enrichment method in Listeria enrichment broth, followed by plating onto supplemented Oxford agar. For final identification of suspected colonies a multiplex-PCR assay, using two pair of primers was employed. The prs primers are specific for putative phophoribosyl pyrophosphate synthetase [prs] gene of Listeria spp. and the LM lip1 primers are specific for prf A gene of its monocytogenes serovar. Using this method, the contamination of raw milk with L. monocytogenes was determined to be 4% and the sensitivity of the primers was 3.5 x 10[3] cfu ml[-1], and the specificity was determined to be 100%. Considering the high specificity and sensitivity of the employed multiplex-PCR assay, it is recommended to use this method for the identification of suspected colonies of Listeria spp. And L. monocytogenes