ARTICLE INFO

Article Type

Original Research

Authors

Rahimi   M. (1)
Saadatnia ‎   G. (*)
Salehian ‎   P. (2)






(*) Biotechnology Research Institute, Iranian Research Organization for Science and Technology (IROST)‎, Tehran, Iran
(1) ‎Basic Science Faculty, Science and Research Branch, Islamic Azad University, Tehran, Iran
(2) ‎Dr. Salehian medical laboratory, Tehran, Iran

Correspondence

Article History

Received:  April  29, 2017
Accepted:  October 11, 2017
ePublished:  November 15, 2018

BRIEF TEXT


Group B Streptococcus (GBS) is a gram-positive bacterium that lives in many bacteriological ‎environments. This bacterium can colonize in the human digestive system and the genital area of ‎women. The presence of this colonization in the delivery canal at the end of pregnancy may result in ‎serious neonatal and maternal infections [1].‎

GBS colonization in the vagina increases the risk of premature birth and can predispose a person to ‎chorioamnionitis during labor. GBS can cause asymptomatic bacteriuria during pregnancy, indicating ‎high levels of infection with the genital tract [2].‎ GBS or Streptococcus agalactia is one of the major causes of meningitis, sepsis and death in newborn ‎babies in developed and developing countries. Approximately 10-40% of pregnant women transmit ‎GBS to their babies. Of the infected infants, they progress in 1-3% of cases, and almost always the ‎onset of infection begins at the first 24 hours of birth and leads to sepsis and meningitis [3, 4]. ‎... [5]. Given the severity and spread of GBS infection and the importance of maternal and neonatal ‎health against postpartum infections, CDC and the United States College of Gynecologists and the ‎Academy of Physicians in 2002, screened pregnant women for the purpose of detecting GBS ‎colonization for timely treatment and prevention of infection transmission has suggested to newborns ‎‎[6].‎ ‎.... The best time to perform a screening test is 35-37 weeks of gestation and in mothers who have had ‎rupture of embryonic sac or have a history of Streptococcus B in their previous neonates, and who ‎have urinary tract infections in the current pregnancy, or fever above 38 ° C, These risk factors must be ‎considered [7]. Research has shown that treatment with antibiotic 2 hours before birth, reduces the ‎risk of transmission [8].‎

There has been a lot of research about the placement of group B streptococci in the mother and its ‎transmission to newborn babies and infantile diseases caused by it. However, so far, no study has been ‎conducted on its placement in placenta. The aim of this study was to investigate the presence of group ‎B streptococcus in a placenta in pregnant women infected with this bacterium.‎

This is an analytical case-control study.

In this study, samples were taken from women who referred to Sarem Hospital in Tehran for delivery ‎during the years 2012 to 2013.‎

In total, 80 paraffin blocks of tissue samples from placenta samples were examined. Samples were ‎prepared from Paraffin Blocks bank of the Department of Pathology in Sarem Hospital, which consisted ‎of 30 samples from the placenta of persons infected with Streptococcus B group with amniotic ‎membrane inflammation, 25 samples from the placenta of persons with infected bacteria but without ‎amniotic membrane inflammation, and 25 samples from the placenta of healthy individuals (non-‎infected with bacterium) but with amniotic membrane inflammation, which was considered as the ‎control group.‎

Using microtome, 4 to 5 micrometers of each block were prepared and placed in sterile micro tubes. ‎DNA extraction was performed using a DNA extraction kit (Roche, Germany) according to the protocol ‎contained in the kit. Then the DNA extracted from the samples was concentrated and the samples were ‎examined on an agarose gel to ensure the extraction accuracy. For all samples, the band was observed.‎ ‎ In this research, a specific fragment of the cfb Streptococcus group B was amplified with 153 bp. ‎Specific used primers included sag059 and sag190, which were selected as templates for genomic DNA ‎replication. The sequence of used primers was Sag059: 5'-TTTCACCAGCTGTATTAGAAGTA-3 'and Sag190: ‎‎5'-GTTCCCTGAAACATTATCTTTGAT-3'.‎ To perform the polymerase chain reaction, DNA samples extracted from the placenta and the standard ‎strain DNA (Positive control) were removed from the -20 ° C freezer, and each time, a number of ‎samples were tested, with a negative control (water) and a positive control. To reproduce the desired ‎fraction in thermo cycler, vials were first placed at 94 ° C for 3 minutes, and then 40 cycles were ‎carried out at 94 ° C for 1 minute for denaturation and then it was carried out at 55 ° C for 1 minute for ‎the annealing step. It was carried out at 72 ° C for 1 minute for extension and finally a cycle was carried ‎out at 72 ° C for 3 minutes. Finally, 1.5% agarose gel was used for electrophoresis and 5 μl of each ‎sample was mixed with 1 μL of GelRed and injected into the wells. The results were recorded with a ‎gel-doc device and then they were analyzed. Observation of the band within the bp153 range indicated ‎an infection.‎ ‎

Investigation of placenta in people with amniotic membrane inflammation and positive GBS indicated ‎that there was no bacterial DNA in these samples. No DNA of bacterium was found in any of the ‎samples used in this study. If the band was seen in the negative control, it was a sign of contamination ‎and the experiment was repeated.‎

‎... [9]. A lot of studies have been done on the establishment of Streptococci in group B in the mother ‎and its transmission to infants born and GBS infantile diseases. However, so far no study has been ‎conducted on its placement in placenta. .... [10].‎ ‎....The list of organisms that are normally isolated from amniotic fluid and frequently found in ‎inflammation of embryonic membranes are aerobic bacteria, genital mycoplasmas, GBS, and E. coli ‎‎[11]. .... [12].‎ McDonald's and Chambers's study emphasized the relationship between amniotic fluid ‎microorganisms and early delivery, and found the inept (unidentified) UTI as the main underlying ‎abortion in cases that considered GBS as a key pathogen in this regard [13]. In a study in women with ‎preterm delivery, the incidence of corioammononitis was reported twice in the second trimester [14]. ‎However, other researchers in the same year concluded that inter-Amniotic Infection was not the main ‎reason for early delivery between weeks 20 to 36 in pregnant women without any symptoms with ‎healthy membranes [15].‎ The role of mixed infections in the etiology of early delivery requires further study. Studies have ‎shown that some pathogenic bacteria such as GBS primarily attack amniotic fluid and chorioamnion, ‎enter the embryo and begin their work and lead to spontaneous abortion. Amniotic fluid infection is ‎one of the major causes of spontaneous abortion, and may occur in the presence of a healthy ‎membrane without sepsis symptoms. Group B streptococci is one of the major pathogens involved in ‎abortion with or without membrane infections, and their infection has a role in early preterm labor. ‎Severe colonization of GBS in vagina with preterm labor is also associated with subsequent pregnancy ‎‎[13, 16].‎

It is suggested that in future studies, other possible pathways that can infect people with this ‎bacterium, such as mother's mouth and teeth, and transmission of bacterial-specific antibodies to the ‎fetus be investigated.‎ ‎

According to the findings of this study, with limited number of samples and only one study, accurate ‎conclusion cannot be achieved, and the mechanism of the infection in the genital system remains ‎unknown and requires more research and more efficient methods.‎

Group B streptococcal bacteria are not present in the placenta of women infected with GBS (with or ‎without amniotic membrane inflammation).‎





This article is the result of a master's degree in biology in branch of microbiology in Islamic Azad ‎University, Research and Science Branch, and it was sponsored by the Sarem Cell Research Center.‎ ‎




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