ABSTRACT
       Background and Objectives: Q fever is a zoonotic disease caused by an obligate gram-negative intracellular pathogen called Coxiella burnetii. The aim of this study was to determine the seroprevalence of anti-C. burnetii antibodies in bulk tank milk (BTM) samples of dairy cattle in west and northwest of Iran.
       Methods: Overall, 71 BTM samples (covering nearly 700 dairy cattle) were collected in autumn 2013. A commercial Q fever antibody ELISA Test Kit (Liebefeld-Bern, Switzerland) was used to identify the presence of antibodies against inactivated phase 1 and phase 2 C. burnetii antigens.
       Results: The results of ELISA test showed that 17 BTM samples (23.9%) were positive for the presence of anti-C. burnetii antibodies.
       Conclusion: This study is the first to evaluate presence of anti-C. burnetii antibodies in BTM samples from dairy cattle herds in west and northwest of Iran. The high prevalence of this pathogen highlights the need for pasteurization of raw milk and raising awareness in consumers of dairy products in these regions.
           Keywords: Q fever, Cattle, Iran, Coxiella.

ABSTRACT

        Background and Objectives: Ivermectin is an anti-parasitic medication frequently used in many food-producing animals. This study aimed to investigate the level of ivermectin residue in liver samples collected from slaughterhouses in Qazvin Province, Iran.

        Methods: Overall, 88 bovine liver samples were randomly collected and analyzed for detection of ivermectin residues. The samples were analyzed for ivermectin contamination by enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The samples were extracted using liquid-liquid extraction procedure for the ELISA. Solid phase extraction using a C18 column followed by fluorescence-derivatized with 1-methylimidazole and trifluoroacetic anhydride in acetonitrile were used for the HPLC assay. Recovery values obtained from the HPLC method ranged from 81.3 to 92.5%, with a relative standard deviation of 6.7-12.2%.

        Results: First, all samples were screened by the ELISA method. Based on the results, 16 samples (18.2%) contained no detectable levels of Ivermectin residue, while Ivermectin was found in 72 samples (81.8%). In addition, 22 of the positive samples (30.55%) contained high Ivermectin level (>50 ppb). Analysis of the samples by the HPLC method showed that eight samples (9.09%) contained ivermectin levels above the maximum residue limit.

        Conclusion: This study demonstrates the presence of different levels of Ivermectin residue in bovine liver samples collected from the Qazvin Province in Iran. Therefore, regulatory authorities should ensure proper withdrawal period before slaughter of the animals.

       Keywords: Ivermectin, Cattle, Liver, ELISA, HPLC.

ABSTRACT
       Background and Objectives: Mastitis caused by Staphylococcus aureus is a widely distributed disease in cattle, goats and sheep. The infection is often subclinical in cattle, leading to reduced milk production and quality, but acute catarrhal or even gangrenous inflammation may also occur. The aim of this study was to investigate resistance of S. aureus isolates from bovine subclinical mastitis to a number of antibiotics.
          Methods: Milk samples were collected from 120 cows in different regions of Tabriz, Iran. Milk samples were cultured and bacteriological identification was performed. Antimicrobial susceptibility of the isolates was assessed by determining minimum inhibitory concentration. Plasmid DNA was extracted by an alkaline lysis method. 
         Results: The highest frequency of resistance was observed against gentamicin (100%) and β- lactam antibiotics including amoxicillin (96%), ampicillin (40%) and penicillin (96%). The isolates mostly contained large plasmids, which might harbor acquired antibiotic resistance.
         Conclusion: The results confirm the high frequency of antibiotic resistance among staphylococci isolated from bovine subclinical mastitis.
           Keywords: Anti-infective Agents, Cattle, Staphylococcus Aureus, Mastitis, Plasmids.