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  <front>
    <journal-meta id="journal-meta-1">
      <journal-title-group>
        <journal-title>Biomedical Research and Therapy</journal-title>
      </journal-title-group>
      <publisher>
        <publisher-name>Biomedpress</publisher-name>
      </publisher>
    </journal-meta>
    <article-meta id="article-meta-1">
      <title-group>
        <article-title id="at-7fbcd453777d">
          <bold id="strong-1">Assessment of probiotic effects on colorectal surgery complications: A </bold>
          <bold id="strong-2">double blinded, </bold>
          <bold id="strong-3">randomized </bold>
          <bold id="strong-4">clinical </bold>
          <bold id="strong-5">trial</bold>
        </article-title>
      </title-group>
      <contrib-group>
        <contrib id="c-6e1aa2d097bd">
          <name id="n-4fd7d94410af">
            <surname>Kakaei</surname>
            <given-names>Farzad</given-names>
          </name>
          <contrib-id contrib-id-type="orcid"/>
          <xref id="x-10452bf0a29f" rid="a-0125b7d3a376" ref-type="aff">1</xref>
        </contrib>
        <contrib id="c-c5221b8dba2b">
          <name id="n-3dba0687c6e8">
            <surname>Shahrasbi</surname>
            <given-names>Mohammadreza</given-names>
          </name>
          <contrib-id contrib-id-type="orcid"/>
          <xref id="x-ce8cd27aa54f" rid="a-607607416a8d" ref-type="aff">2</xref>
        </contrib>
        <contrib id="c-d7fac94e1bef" corresp="true">
          <name id="n-77d32b0248ee">
            <surname>Kermani</surname>
            <given-names>Touraj Asvadi</given-names>
          </name>
          <email>tooraj_asvadi2005@yahoo.com</email>
          <contrib-id contrib-id-type="orcid"/>
          <xref id="x-48fb2fd5987e" rid="a-51621bc637a0" ref-type="aff">3</xref>
        </contrib>
        <contrib id="c-2a458759a8fe">
          <name id="n-def998c240e5">
            <surname>Taheri</surname>
            <given-names>Sahar</given-names>
          </name>
          <contrib-id contrib-id-type="orcid"/>
          <xref id="x-dc6a91ead16a" rid="a-a77c8e8d9728" ref-type="aff">4</xref>
        </contrib>
        <contrib id="c-3905369dccf8">
          <name id="n-e48af94f5bd1">
            <surname>Tarvirdizade</surname>
            <given-names>Kowsar</given-names>
          </name>
          <contrib-id contrib-id-type="orcid"/>
          <xref id="x-50cfbd70a66f" rid="a-fac753f58092" ref-type="aff">5</xref>
        </contrib>
        <aff id="a-0125b7d3a376">
          <institution>Associate Professor of Surgery and Transplantation, Department of General and Vascular Surgery, Tabriz University of Medical Science, Tabriz, Iran</institution>
        </aff>
        <aff id="a-607607416a8d">
          <institution>Asisstant of General and Vascular Surgery, Department of General and Vascular Surgery, Tabriz University of Medical Science, Tabriz, Iran</institution>
        </aff>
        <aff id="a-51621bc637a0">
          <institution>Asisstant Professor of General and Vascular Surgery, Fellowship of Trauma, Department of General and Vascular Surgery, Tabriz University of Medical Science, Tabriz, Iran</institution>
        </aff>
        <aff id="a-a77c8e8d9728">
          <institution>Asisstant of Gynecology and Obstetrics, Department of Gynecology and Obstetrics, Alzahra Hospital, Tabriz University of Medical Science, Tabriz, Iran</institution>
        </aff>
        <aff id="a-fac753f58092">
          <institution>General Practitioner, Faculty of Medicine, Tabriz University of Medical Science, Tabriz, Iran</institution>
        </aff>
      </contrib-group>
      <abstract id="abstract-8f4321c12afe">
        <title id="abstract-title-a397bf0f0dea">Abstract</title>
        <p id="paragraph-90629563c26e"><bold id="s-8a1f4e0ce7fb">Background: </bold>Probiotics are living bacteria, which can be used as a food supplement to produce inhibitory agents and compete with pathogens in the guts<bold id="s-a22e6a93ac6a">. </bold> Nowadays, because of the easy accessibility and misuse of antibiotics, probiotic usage is increasing. The goal of our study is to assess the effects of probiotics on colorectal surgery complications. <bold id="s-6a39b8d8aed3">Methods</bold>: The enrolled cases were selected from colorectal surgery candidate patients, who referred to Sina and Imam Reza Hospitals of Tabriz University from April of 2016 to April of 2017. They were divided into two groups of study and control. For the study group, 7 days before surgery, one capsule of probiotics (Familact) was administrated every night, while the control group was given capsules of placebo. <bold id="s-822c4d6444e8">Results</bold>: Although the infective complications, mortality ratio and duration of hospitalization in the study group were lower than the control group, these differences were not statistically significant. <bold id="s-028d83074304">Discussion: </bold>Our study confirmed that preoperative probiotic consumption in colorectal surgery had not affected complications or mortality of surgery and this finding is in disagreement with some previous studies. Perhaps, other strains of bacteria or different dosage, duration and rout of administration can have positive effects on these complications. <bold id="strong-6">Conclusion:</bold> This study showed that there was no correlation between probiotic consumption preoperatively and decreased complications or mortality after colorectal surgery.</p>
        <p id="p-f697b3ba740e"/>
      </abstract>
      <kwd-group id="kwd-group-1">
        <title>Keywords</title>
        <kwd>Colorectal surgery</kwd>
        <kwd>Complications</kwd>
        <kwd>Probiotics</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec>
      <title id="t-d0ecbbe02a75">Introduction</title>
      <p id="p-7130c80fc9d8">Probiotics are living bacteria that can be used as food supplementary to produce inhibitory agents to compete with pathogens in the guts. They can stimulate and regulate the immune system and improve the balance of intestinal microbes <xref rid="454100:10083197" ref-type="bibr">1</xref>,<xref rid="454100:10083198" ref-type="bibr">2</xref>,<xref rid="454100:10083199" ref-type="bibr">3</xref>.</p>
      <p id="p-fd61279210f2">Recent studies showed that probiotics can reduce the absorption of cholesterol and decrease the risk of colorectal cancer <xref id="x-84242db6a04c" rid="454100:10083181" ref-type="bibr">4</xref>. Probiotics can also help improving diseases such as diarrhea, constipation, allergies, inflammatory bowel disease, irritative bowel syndrome, peptic ulcer and lactose intolerance, and can prevent autoimmune diseases and hypertension <xref rid="454100:10083182" ref-type="bibr">5</xref>,<xref rid="454100:10083180" ref-type="bibr">6</xref>,<xref rid="454100:10083186" ref-type="bibr">7</xref>.  </p>
      <p id="p-1372e84ac5a0">The combination of probiotics and prebiotics (food ingredients that induce the growth or activity of beneficial microorganisms) is known as “synbiotics” <xref id="x-fb3574fde768" rid="454100:10083195" ref-type="bibr">8</xref>. Synbiotics help to improve the resistance of the gastrointestinal tracts to infected diseases by improving the immune system and antimicrobial activities <xref id="x-d63d4be23356" rid="454100:10083194" ref-type="bibr">9</xref>. </p>
      <p id="p-9f58e5a0c8ce">Probiotics colonize in the gastrointestinal tract and oropharynx. They prevent the changes of normal flora into pathogens and have preventive effects on hospital pneumonia <xref rid="454100:10083195" ref-type="bibr">8</xref>,<xref rid="454100:10083191" ref-type="bibr">10</xref>,<xref rid="454100:10083184" ref-type="bibr">11</xref>.</p>
      <p id="p-ec553479b162">Nowadays because of the easy accessibility and misuse of antibiotics, their usage is increasing, which leads to growing resistance of the microorganisms <xref id="x-71923967b2fa" rid="454100:10083183" ref-type="bibr">12</xref>. Recent studies showed that preoperative administration of probiotics in patients with colorectal cancer can reduce infective complications after surgery <xref rid="454100:10083190" ref-type="bibr">13</xref>,<xref rid="454100:10083176" ref-type="bibr">14</xref>,<xref rid="454100:10083189" ref-type="bibr">15</xref>. The goal of our study is to assess the effects of probiotics on the colorectal surgery complications.</p>
      <p id="p-e69e4b6d090b"/>
    </sec>
    <sec>
      <title id="t-b2dcf593f399">Methods</title>
      <p id="p-a2cd5419a3ed">This is a randomized clinical trial and a prospective study. The enrolled cases were selected from colorectal surgery candidate patients, who referred to Sina and Imam Reza Hospitals of Tabriz University of Medical Sciences, Tabriz, Iran, from April 2016 to April 2017. All 18- to 80-year-old patients with good nutritional status were divided into two parallel groups of study and control. </p>
      <p id="p-3f4e15fc6203">Exclusion criteria were set for patients with no agreement for participation in study, having intestinal or colon obstruction, consuming anticoagulant agents or any other drugs that prolong duration of hospitalization, having progressive cardiopulmonary diseases or Class IV of ASA (American Society of Anesthesiologists) or chronic renal failure, having a history of chemotherapy, or patients with organ transplantation, cirrhosis, antibiotics usage one week before surgery, consuming steroids and being pregnant or lactating.</p>
      <p id="p-8d86e140584d"/>
      <fig id="f-0a9aad1af6e5" orientation="potrait" width="twocolumn" fig-type="graphic" position="anchor">
        <graphic id="g-a1ec74fd8322" xlink:href="https://typeset-prod-media-server.s3.amazonaws.com/article_uploads/04ea0ca0-3811-43a4-9b40-fcc2ceac58f8/image/15778cf7-3cd8-4d3a-8a57-0deca037a999-u131-1549299469-1.png" width="63"/>
        <label>Figure 1 </label>
        <caption id="c-181bde7a142e">
          <title id="t-8620fdb13bbf">
            <bold id="s-7c4f76943a05">Flow diagram of recruitment and retention of participants in the study: due to death of patient only one patient in control group dropped out.</bold>
          </title>
        </caption>
      </fig>
      <p id="p-52db77149c55"/>
      <sec>
        <title id="t-f6f90de86702">Randomization and blinding</title>
        <p id="p-7a612a996e01">We used statistical software in <italic id="e-4d0e76e2a0aa"><bold id="s-8729814a45a1">www.randomizer.org</bold></italic> for double blinded randomization. Two equal groups received either probiotics or placebos. Each group consisted of 50 patients and the sample size was determined according to previous studies <xref id="x-5f204b44f1f3" rid="454100:10083189" ref-type="bibr">15</xref>. Two boxes labelled A (probiotics) and B (placebo) were prepared <bold id="s-adb8412a2de0"><xref id="x-cc3a71eaf926" rid="f-0a9aad1af6e5" ref-type="fig">Figure 1</xref></bold>. The patient’s nurses were also blinded and received sealed envelopes of letter A or B Patients will be given capsules based on the letters defined on the envelopes. All data was collected by Dr. M.SH., who was also blinded to the types of drugs during 30 days of follow-up.</p>
        <p id="p-11e5a455a71a"/>
      </sec>
      <sec>
        <title id="t-abbb794d0eb5">Procedure<italic id="emphasis-2"/></title>
        <p id="p-ef3d964517c4">For the study group, 7 days before surgery, one capsule of probiotics (Familact) was administered every night. Each capsule contains <italic id="e-8393647fe2b7">Lactobacillus casei </italic>&amp; <italic id="e-b6bfc7239cf5">Lactobacillus acidophilus</italic> (1.75 x 10<sup id="s-3f5ecb0226d1">9</sup>CFU), <italic id="e-0ca760cb11ff">Lactobacillus plantarum</italic> (0.5 x10<sup id="s-e69bbe86cf55">9</sup>CFU), <italic id="e-f16f230e5eff">Bifidobacterium breve </italic>(1.75 x 10<sup id="s-afc47d8cfa8e">9</sup>CFU), <italic id="e-c2811ef7edd8">Bifidobacterium longum</italic> (1.5 x 10<sup id="s-0095327899d4">9</sup>CFU), and <italic id="e-e3ca4f01b776">Streptococcus thermophilus</italic>, and the control group was given placebo capsules.</p>
        <p id="p-cfd919fe94c4">For bowel preparation, one day before surgery, four packets of oral polyethilenglycol with two litres of water was administrated. All patients took oral erythromycin 800 mg and metronidazole 500 mg at 13, 14 and 23 o’clock. Thirty minutes before operation, cefazolin was infused as prophylactic antibiotics, and if there was no contamination after 48 hours, this step was discontinued; however if there was contamination, antibiotic prescription was changed by attending surgeons.</p>
        <p id="p-447affe7015a">After the operation, each patient was given one oral capsule daily when awake. Each patient was given 30 capsules in total.</p>
        <p id="p-ef7d34d6714c">The control group received similar treatments except that placebo was used instead of probiotics. </p>
        <p id="p-399f627de36f"/>
      </sec>
      <sec>
        <title id="t-312f1eed50d1">Measures</title>
        <p id="p-1d7f601264ec">Variables of the study including gender, age, past medical history, measurement of haemoglobin, incidence of anastomosis leakage, cutaneous or subcutaneous infection on incision line, facia dehiscence, other infections (pneumonia, urinary tract infection, central venous catheter infection and sepsis), duration of hospitalization and mortality ratio were defined.</p>
        <p id="p-deba950ca5bd"/>
      </sec>
      <sec>
        <title id="t-37daecdf1960">Statistical Analysis</title>
        <p id="p-0e66d1d47f8e">All data were analysed by SPSS version of 15. We used chi-square test for qualitative variables analysis and t-test for quantitative variables. P-Values of ≤ 0.05 were considered reliable.</p>
        <p id="p-ea9ea4e0e091"/>
      </sec>
      <sec>
        <title id="t-ad3466a263d8">Ethics</title>
        <p id="p-ade7aee5d75e">The study design was approved by Human Research Review and Ethics Committee of Tabriz University of Medical Sciences. All patients were informed about the study, and they had to sign the consent letter for voluntary cooperation. Also, they could leave the study at any time. All personal information were confidential. The only intervention in the treatment was the prescription of Familact capsules. A company of Zist Takhmir produced these capsules as OTC (Over-The-Counter) drugs that had no complications in studies until now. Costs of study were funded by the Vice Chancellor for Research (VCR) of Tabriz University of Medical Sciences.</p>
        <p id="p-433d25ae4c63"/>
      </sec>
    </sec>
    <sec>
      <title id="t-3fa75adb367d">Results</title>
      <p id="p-b0c31c27e87b">There were no significant differences in gender, age, past medical history and haemoglobin levels between two groups (P-value&gt; 0.05) (<bold id="s-70f448e85755"><xref id="x-799afbd01441" rid="tw-4495a971e53f" ref-type="table">Table 1</xref></bold>).  </p>
      <table-wrap id="tw-4495a971e53f" orientation="potrait" width="twocolumn">
        <label>Table 1</label>
        <caption id="c-64c9238777c6">
          <title id="t-2931a4cce463">
            <bold id="s-cc2a83025386">Patient characteristics </bold>
          </title>
        </caption>
        <table id="table-1" rules="rows">
          <colgroup>
            <col width="38"/>
            <col width="23.549999999999997"/>
            <col width="23.919999999999998"/>
            <col width="14.530000000000001"/>
          </colgroup>
          <tbody id="table-section-1">
            <tr id="table-row-1">
              <td id="table-cell-1" align="left"/>
              <td id="table-cell-2" align="left">Group received probiotics</td>
              <td id="table-cell-3" align="left">Group received placebo</td>
              <td id="table-cell-4" align="left">P-value</td>
            </tr>
            <tr id="table-row-2">
              <td id="table-cell-5" align="left">Age, mean   ±  SD (y) </td>
              <td id="table-cell-6" align="left">  50.08±12.64 </td>
              <td id="table-cell-7" align="left">  48.92±11.23 </td>
              <td id="table-cell-8" align="center">  0.40 </td>
            </tr>
            <tr id="table-row-3">
              <td id="table-cell-9" align="left">Male Gender, n (%) </td>
              <td id="table-cell-10" align="left">  29(58) </td>
              <td id="table-cell-11" align="left">  26(52) </td>
              <td id="table-cell-12" align="center">  0.68 </td>
            </tr>
            <tr id="table-row-4">
              <td id="table-cell-13" align="left">Past Medical History, n (%) </td>
              <td id="table-cell-14" align="left"/>
              <td id="table-cell-15" align="left"/>
              <td id="table-cell-16" align="center">0.71</td>
            </tr>
            <tr id="table-row-5">
              <td id="table-cell-17" align="left">- No disease </td>
              <td id="table-cell-18" align="left">  29(58) </td>
              <td id="table-cell-19" align="left">  31(62) </td>
              <td id="table-cell-20" align="left"/>
            </tr>
            <tr id="table-row-6">
              <td id="table-cell-21" align="left">- Diabetes Mellitus type II </td>
              <td id="table-cell-22" align="left">  8(16) </td>
              <td id="table-cell-23" align="left">  4(8) </td>
              <td id="table-cell-24" align="left"/>
            </tr>
            <tr id="table-row-7">
              <td id="table-cell-25" align="left">- Hypertension </td>
              <td id="table-cell-26" align="left">  7(14) </td>
              <td id="table-cell-27" align="left">  11(22) </td>
              <td id="table-cell-28" align="left"/>
            </tr>
            <tr id="table-row-8">
              <td id="table-cell-29" align="left">- Heart Disease </td>
              <td id="table-cell-30" align="left">  3(6) </td>
              <td id="table-cell-31" align="left">  2(4) </td>
              <td id="table-cell-32" align="left"/>
            </tr>
            <tr id="table-row-9">
              <td id="table-cell-33" align="left">- Familial Colorectal Cancer </td>
              <td id="table-cell-34" align="left">  1(2) </td>
              <td id="table-cell-35" align="left">  1(2) </td>
              <td id="table-cell-36" align="left"/>
            </tr>
          </tbody>
        </table>
      </table-wrap>
      <p id="paragraph-43">There were no reports of anastomosis leakage or facia dehiscence from two groups. Three patients (6%) in the study group and 5 patients (10%) from control group developed cutaneous and subcutaneous tissues infection on incision line after surgery. However, this difference was not statistically significant (P-value = 0.46). There was one case of central venous catheter infection in the study group. There was one case of pneumonia that led to respiratory failure and death, and one case of central venous infection in control group, however, there were no significant differences (P-value=0.60 and 0.31) in other infective complications and mortality ratio between two groups. Mean of hospitalization duration of the study group was 5.96 ± 2.53 days (Max = 12days, Min = 3 days) and of the control group was 6.10 ± 2.44 days (Max = 15 days, Min = 3 days), which showed no significant differences (P-value = 0.30) <bold id="s-8264f774c8fc"><xref id="x-36c745eb533e" rid="tw-d078dade32ce" ref-type="table">Table 2</xref></bold>.</p>
      <p id="p-4d9ada81b00c"/>
      <table-wrap id="tw-d078dade32ce" orientation="potrait" width="twocolumn">
        <label>Table 2</label>
        <caption id="c-383f9c35e8df">
          <title id="t-f1f399c8d237">
            <bold id="s-85b4f2acae1a">Comparing of Colorectal Surgery’s Complications in two groups of probiotic consumption and not</bold>
          </title>
        </caption>
        <table id="table-2" rules="rows">
          <colgroup>
            <col width="40.7"/>
            <col width="22.289999999999996"/>
            <col width="20.130000000000003"/>
            <col width="16.88"/>
          </colgroup>
          <tbody id="table-section-2">
            <tr id="table-row-13">
              <td id="table-cell-49" align="left"> </td>
              <td id="table-cell-50" align="left">Probiotic Received</td>
              <td id="table-cell-51" align="left">Placebo Received</td>
              <td id="table-cell-52" align="left">P-value</td>
            </tr>
            <tr id="table-row-14">
              <td id="table-cell-53" align="left">Anastomosis Leakage</td>
              <td id="table-cell-54" align="left">0%</td>
              <td id="table-cell-55" align="left">0%</td>
              <td id="table-cell-56" align="left">1</td>
            </tr>
            <tr id="table-row-15">
              <td id="table-cell-57" align="left">Fascia Dehiscence</td>
              <td id="table-cell-58" align="left">0%</td>
              <td id="table-cell-59" align="left">0%</td>
              <td id="table-cell-60" align="left">1</td>
            </tr>
            <tr id="table-row-16">
              <td id="table-cell-61" align="left">Infection of Surgical Site</td>
              <td id="table-cell-62" align="left">6%</td>
              <td id="table-cell-63" align="left">10%</td>
              <td id="table-cell-64" align="left">0.46</td>
            </tr>
            <tr id="table-row-17">
              <td id="table-cell-65" align="left">Other Infective Complications</td>
              <td id="table-cell-66" align="left">2%</td>
              <td id="table-cell-67" align="left">4%</td>
              <td id="table-cell-68" align="left">0.60</td>
            </tr>
            <tr id="table-row-18">
              <td id="table-cell-69" align="left">Mean of Hospitalization Duration</td>
              <td id="table-cell-70" align="left">5.96  ±  2.53</td>
              <td id="table-cell-71" align="left">6.10  ±  2.44</td>
              <td id="table-cell-72" align="left">0.30</td>
            </tr>
            <tr id="table-row-19">
              <td id="table-cell-73" align="left">Mortality</td>
              <td id="table-cell-74" align="left">0%</td>
              <td id="table-cell-75" align="left">2%</td>
              <td id="table-cell-76" align="left">0.31</td>
            </tr>
          </tbody>
        </table>
      </table-wrap>
      <p id="p-dae75c161dd8"/>
    </sec>
    <sec>
      <title id="t-4a294a6919ac">Discussion</title>
      <p id="p-2beb8400a168">In this study, the effects of probiotic consumption on complications of elective colorectal surgery and its mortality ratio was assessed. The results showed that probiotics had no positive effect on patients after surgery. </p>
      <p id="p-0d07114895ea">McNaught <italic id="e-d01d5bf4a37d">et al.</italic> (2002) showed that preoperatively (1 week) oral probiotic (<italic id="e-88a8263c4fc0">lactobacillus</italic>+ <italic id="e-221f910f1c78">plantarum</italic> 299v) administration in 129 patients with elective abdominal surgery had no positive effects on the growth of beneficial bacteria in guts, nor did it help to improve the resistance of intestinal cells or decrease the postoperative complications and mortality <xref id="x-e2b595f0b8a2" rid="454100:10083192" ref-type="bibr">16</xref>. These results were in agreement with our study.</p>
      <p id="p-ef43d88ff82d">In the study of Anderson and McNaught <italic id="e-c5794973c387">et al.</italic> (2004), candidate patients for elective abdominal surgery took synbiotics (probiotics such as <italic id="e-21c372209f33">Lactobacillus acidophilus</italic> La5 with prebiotics like oligofructose) for 2 weeks. There was no significant difference between control and study groups, which confirmed our study results <xref id="x-90eb97cc9834" rid="454100:10083177" ref-type="bibr">17</xref>.</p>
      <p id="p-f3f98dca1a54">Most studies in these field showed different results. In the study of Sagawara <italic id="e-53ca41b51004">et al.</italic> (2006), patients, who were candidates for hepatectomy with bile duct carcinoma and liver hilum involvement, were divided into two groups of receiving synbiotics or placebo (for two weeks before surgery). The results showed that the administration of synbiotics preoperatively increased lymphocytes and natural killer activities, and decreased the production of IL-6. Also, in the group receiving synbiotics only after surgery, white blood cells count was significantly lower compared to control group, thus, synbiotic administration before surgery could improve the immune system <xref id="x-e3096d215d3e" rid="454100:10083196" ref-type="bibr">18</xref>.</p>
      <p id="p-898200d8ef9a">Rayes <italic id="e-c4cc3805916c">et al</italic>. (2007) showed that synbiotics had positive effects on patients. They administrated synbiotics through intestine and found that infection ratio and antibiotic requirements in group treated with lactobacillus probiotics were significantly lower compared to controls <xref id="x-7b72c3855b8b" rid="454100:10083193" ref-type="bibr">19</xref>. </p>
      <p id="p-22b1bb8cd9c7">Liu <italic id="e-880a2895915e">et al</italic>. (2011) in a randomized clinical trial had prescribed oral probiotics to colorectal cancer patients 6 days before and 10 days after colorectal surgery, and assessed theme effects on bowel activities and postoperative infections. Unlike us, they showed that probiotics could reduce postoperative infections. On the other hand, this study revealed positive effects of probiotics in a diversity of intestinal flora and the excretion of various bacteria in the stool. Therefore, they recommended probiotics as a drug to use before surgery that can increase the resistance of epithelial cells to toxins and inflammative factors <xref id="x-a59746f908c5" rid="454100:10083189" ref-type="bibr">15</xref>. </p>
      <p id="p-2184754f994a">Liu <italic id="e-6480a1a587ce">et al</italic>. (2013) examined the effects of probiotics on the levels of serum xenoline and their association with infection rates. In this study, 150 patients of colorectal cancer were divided into two groups of controls and cases and received oral probiotics 6 days before- and 10 days after surgery. The results showed that the probiotics had positive effects on the significant reduction of serum xenoline and on reducing intestinal permeability, which led to decreased postoperative infections and antibiotic requirement <xref id="x-2381bb8b723a" rid="454100:10083190" ref-type="bibr">13</xref>. </p>
      <p id="p-8f8c27ef3648">Liu <italic id="e-f029a38bb1f5">et al</italic>. in another study (2015) concluded that probiotics reduced postoperative infections in patients with liver metastasis <xref id="x-0247e13c7494" rid="454100:10083188" ref-type="bibr">20</xref>.</p>
      <p id="p-43e0c034951d">Three systematic reviews (2017) and one meta-analysis (2015) also confirmed the protective effects of probiotics and synbiotics consumption before abdominal surgery, which reduced infective complications such as urinary tract infections, pneumonia and sepsis <xref rid="454100:10083189" ref-type="bibr">15</xref>,<xref rid="454100:10083188" ref-type="bibr">20</xref>,<xref rid="454100:10083178" ref-type="bibr">21</xref>,<xref rid="454100:10083187" ref-type="bibr">22</xref>,<xref rid="454100:10083200" ref-type="bibr">23</xref>,<xref rid="454100:10083185" ref-type="bibr">24</xref>. Liu <italic id="emphasis-6">et al.</italic> recommended a diet that included bacteria of different strains, and this diet was more useful than single-strain diets for surgical infections and other infections <xref id="x-d2338ccde46c" rid="454100:10083187" ref-type="bibr">22</xref>.</p>
      <p id="p-2c7467472d9c">Consoli <italic id="emphasis-7">et al</italic>. (2016) studied about probiotic (Saccharomyces boulardii) consumption in patients with colon surgery and the levels of inflammatory cytokines. They found that in the study group, the levels of mucosal IL-1 beta, IL-10 and IL- 23 were lower and probiotic administration before surgery had no effect on infective complications, duration of hospitalization and mortality <xref id="x-65f965d31402" rid="454100:10083179" ref-type="bibr">25</xref>.</p>
      <p id="p-c97a80dc52e6">A numerous causes could affect the results of our study, including the strains of probiotics that were used. Perhaps, other strains of probiotics could be considered in future research. Moreover, dosage, duration and different routes of probiotic administration, such as direct administration into the jejunum, could be considered for further research. On the other hand, prophylactic antibiotics can also reduce the effect of probiotics and need to be taken into account in the future.</p>
      <p id="p-f31ae0e31d4a"/>
    </sec>
    <sec>
      <title id="t-018c1b34b767">Conclusions</title>
      <p id="p-023cc43caf01">This study showed that there is no correlation between probiotic consumption preoperatively and the decrease in complications and mortality after surgery.</p>
      <p id="p-90d9b041d3d4">Study with larger groups, longer administration of probiotics or synbiotics, longer follow-up duration and other administration routes are recommended.</p>
      <p id="p-475bd9afcf0e"/>
    </sec>
    <sec>
      <title id="t-a9ff1df7c57b">Competing Interests</title>
      <p id="p-57c20ddb518b">We don’t declare under financial, general, and institutional competing interests. We had full access to all study data, take fully responsibility for the accuracy of the data analysis, and have authority over manuscript preparation and decisions to submit the manuscript for publication.</p>
      <p id="p-57f68d7519ac"/>
    </sec>
    <sec>
      <title id="t-b26392bdbc5d">Authors' Contributions</title>
      <p id="p-9b8e2f9baffe">Study design: Dr. F. Kakaei and Dr. M. Shahrasbi</p>
      <p id="p-b58462abd7d0">Operations: Dr. F. Kakaei</p>
      <p id="p-563792febe6b">Collecting data: Dr. M. Shahrasbi and Dr. S. Taheri</p>
      <p id="p-0803e058d857">Data analysis: Dr. F. Kakaei and Dr. T. Asvadi Kermani</p>
      <p id="p-faf30233848e">Writting the paper:Dr. T. Asvadi Kermani and Dr. K. Tarvirdizade</p>
      <p id="p-2158773082e6">Editting the paper: Dr. F. Kakaei and Dr. T. Asvadi Kermani</p>
      <p id="p-b1c1c6329f8d"/>
    </sec>
  </body>
  <back>
    <ack id="ack-353428e13ab5">
      <title id="ack-title-6f6ebe9fcbde">Acknowledgments</title>
      <p id="t-99c04549c722">We would like to acknowledge Tabriz University of Medical Sciences for supporting.</p>
      <p id="p-c939d4ad5f68"> </p>
      <p id="clipboard_property"> </p>
      <p id="paragraph-586b3f3fe6b3"> </p>
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