Bacterial Sexually Transmitted Infections

Introduction 

Sexually transmitted diseases (STDs) also referred to as venereal diseases (VD) are infections that can be passed from a single person to the other through sexual intercourse, oral sex or anal sex (Ford, 2016). Other sexually transmitted diseases can be moved from one person during childbirth from mother to baby during delivery, through the use of unsterilized drug needles, and through blood transfusions. There exist numerous bacterial sexually transmitted infections such as chlamydia, gonorrhea, syphilis, and chancroid (Pommerville & Alcamo, 2016). This paper gives an account of the various bacterial sexually transmitted infections, precautions for specimen collection, the laboratory diagnosis, bacteria causing the STIs, and pathogenesis of the bacteria. 

A brief account of the bacterial Sexually Transmitted Infections (STIs) and Specimen collected for diagnosis 

Chlamydia 

Chlamydia is a sexually transmitted disease caused by bacterial infection that affects both males and females. Chlamydia is spread through sexual contact between partners of the same or different sex (U.S National Library of Medicine, 2018). According to the Centre for Disease Control and Prevention (CDC), Chlamydia has been reported as the most common (STI) since 1994 in the US. 

Diagnosis 

During the diagnosis of Chlamydia, the physician or medical practitioner is required to examine the patient for physical symptoms such as discharge which should include a swab sample of urine from the urethra, penis, cervix, rectum and throat sample (U.S National Library of Medicine, 2018). 

Gonorrhea 

Gonorrhea, which is also referred to as ‘the clap,' is among the most prevalent sexually transmitted disease with an estimated infection rate of more than 800,000 new cases of infection annually in the US (U.S National Library of Medicine, 2018). Gonorrhea is passed from an infected person to other people through sexual contact (U.S National Library of Medicine, 2018). It is necessary to note that men do not necessarily require ejaculating for gonorrhea transmission to occur as long as the penis, anus, vagina, and mouth are involved, the STI can be spread (U.S National Library of Medicine, 2018). There are also cases of mother to child infection during childbirth. 

Diagnosis 

The gonorrhea test entails collection a sample of urine from the infected area, which is usually the throat, cervix, and rectum, then transporting the sample to the laboratory for examination (U.S National Library of Medicine, 2018). In the laboratory, the bacteria are identified through analysis of the genetic material and culture. 

Syphilis 

Syphilis affects both women and men and occurs in three stages; the primary, secondary and tertiary stage. According to the Center for Disease Control and Prevention (CDC), it was reported in 2015 that Syphilis infection is rampant among men who engage in same-sex or who engage in sexual intercourse with both sexes (males and females). 

Syphilis is transmitted through direct contact with one infected person to another person when the infected sore located on the skin and in mucous membrane is touched (U.S National Library of Medicine, 2018). The syphilitic sore usually occurs in the vagina, lips, mouth, rectum, and anus. 

Diagnosis 

In cases of infection, the doctor carries out the physical examination, and the sexual history of the patient is examined and clinical tests conducted to confirm syphilis infection (U.S National Library of Medicine, 2018). The tests performed include: 

Blood tests investigate the presence of antibodies to the disease which manifests in the case of current or past infection (U.S National Library of Medicine, 2018). 

Bodily fluid: This test involves the examination of the fluid obtained from a chancre during the primary or secondary stage of the disease (U.S National Library of Medicine, 2018). 

Cerebrospinal fluid: The cerebrospinal fluid is collected through a spinal tab and taken to the laboratory for examination and to test the functionality of the nervous system (U.S National Library of Medicine, 2018). 

In case of infection, it is essential for the infected party to notify their sexual partner to be tested and treated. 

Chancroid 

The disease is sexually transmitted as the bacteria attack the genitalia causing the emergence of an open sore that is commonly referred to as chancroid of an ulcer. The spreading of the disease is expedited by the bleeding of the ulcer which produces a contagious fluid that results in the spread of the disease (Healthline, 2017). Although chancroid can be spread through skin contact with an infected party, most cases of infection are usually through oral, vaginal, or anal sexual intercourse. 

Diagnosis 

In cases of infection, diagnosis of chancroid involves the collection of a sample of the fluid obtained from the ulcer or sore (Healthline, 2017). The samples collected are taken to the laboratory where analysis is done. The attending physician could also examine the lymph nodes found in the groin for cases of swelling and to check whether there is any pain (Healthline, 2017). It is not possible to determine infection using blood samples and testing. 

An account of the precautions needed for specimen collection and transport to the laboratory 

Before the selection of the specimen for examination, it is necessary to ensure that a tight sterile container or tubes of transportation are used. The container and tubes will guarantee visibility, prevent the drying of the swab, and prevent the overgrowth of nonpathogenic microorganisms. The containers should also be labeled with the names of the individual patient and the source (Quest Diagnostics, 2018). The general guidelines and precautions during collection and transportation of the swab include: 

The specimen should be obtained before the administration of antibiotics or any other antimicrobial agents. 

The specimen containers used to collect the clinical material should be leak-proof and tightly sealed. 

The materials should be collected where the suspected organism is most likely to be found and with as little external contamination as possible (this is particularly important for draining lesions). 

The specimen collected should be sufficient regarding quantity to permit completion of all tests ordered. 

The provisions should be made for the prompt delivery of the specimen to the laboratory (that is in the time frame of one hour after collection). 

Most of the clinical material such as urine, sputum, and swab material can be held for several hours in a refrigerator before culturing if it cannot be processed immediately. However, body fluids such as CSF or blood should not be refrigerated. 

It is a prerequisite for the specimen for Neisseria gonorrhoeae isolation to be submitted on appropriate isolation plates (Martin-Lewis plates). The inoculated plates should not be refrigerated. 

Cerebrospinal Fluid used for the culture of bacteria 

A separate sterile screw-capped tube containing at least 0.775 mL of cerebrospinal fluid is submitted. In the case of microbiological analysis, it is required to provide the second or third tube down. The collection tube should not be sent. 

Urine Specimen 

The first-morning urine specimen should be collected up to 5mL. The specimen be collected in a sterile plastic container and sent to the laboratory while it is tightly sealed. The urine samples that are raised for routine culture must be transported in the urine transport tubes provided by the medical institute. The samples for mycobacteria are then submitted in a sterile screw cap container after which the urine is kept refrigerated. 

Laboratory Diagnosis- An account of the primary procedures needed for the diagnosis 

Chlamydia 

Chlamydia manifests itself in patients with urogenital, ocular symptoms, and anorectal symptoms (Pommerville & Alcamo, 2016). Diagnostic procedures to detect CT infections include both direct and indirect methods. In many instances, the localized diseases were examined by assays for direct pathogen detection, like culture, antigen tests, nucleic acid, hybridization, and amplification tests. The indirect methods depend on the discovery of antibodies against C. trachomatis that may be applied for diagnostic evaluation of invasive infection and post-infectious complications, like sexually acquired reactive arthritis (Pommerville & Alcamo, 2016). In the above-stated conditions, the pathogens usually cross the epithelial making them undetectable in the swabs. 

Gonorrhea 

Although there exist alternative methods for diagnosing the N gonorrhoeae infection, such as microscopy, the culture method is the one currently preferred. It entails the isolation and identification of the agent causing the disease (Ng & Martin, 2005). Culturing is essential for the isolation of antimicrobial susceptibility testing, surveillance purposes, detecting treatment and characterizing outbreaks (Ng & Martin, 2005). The figure below describes how culturing is done. 

Syphilis 

Direct detection methods 

These are methods that were initially used to directly detect the syphilis-causing bacteria in the past and are currently not being used (Henao-Martinez &Johnson, 3013). They include the dark-field microscopy, PCR, and direct fluorescent antibody testing T pallidum (Henao-Martinez &Johnson, 3013). In most clinics, these methods have been done away with and replaced with serologic tests. 

Serologic tests 

There exist two types of serologic tests classified based on the nature of the kind of antigen the antigen the antibodies are directed against (Pommerville & Alcamo, 2016). Treponemal tests detect antibody to T pallidum proteins (Henao-Martinez &Johnson, 2013). Nontreponemal tests detect antibodies detected against lipoid antigens, damaged host cells, and possibly from treponemes (Pommerville & Alcamo, 2016). Both of these tests are used to determine and confirm the presence and infection of Syphilis (Henao-Martinez &Johnson, 2013). 

Chancroid 

The nucleic amplification techniques (NAAT) are proven reliable methods for the identification of Haemophilus ducreyi in clinical samples (Mestrovic, 2017). These molecular methods are influenced by the specific growth which is why the detection rates are higher in comparison to the classical culturing (Mestrovic, 2017). 

The in-house polymerase chain reaction (PCR) methods have been described in the medical literature, some offering the advantage of the simultaneous testing for other critical sexually-transmitted pathogens (Pommerville & Alcamo, 2016). The serological approach is significant and essential in the diagnosis of acute chancroid as opposed to the highly sensitive methods which are molecular. 

Bacteria causing STDs 

Chlamydia  

Chlamydia is caused by the Chlamydia trachomatis bacteria. The bacteria usually manifest themselves through urogenital, ocular symptoms, and anorectic symptoms (Ford, 2014). The chlamydial load is microbial being associated with clinical presentation, severity in infection, and transmissibility especially in patients with ocular C. trachomatis (Debink et al, 2016). 

Gonorrhea

The sexually transmitted disease affects both males and females. Gonorrhea is caused by a bacterium referred to as Neisseria gonorrhoeae (Ford, 2014). The bacterium is highly infectious and affects the reproductive tract and the mucous membrane of the rectum, mouth, throat, and eyes. 

Syphilis 

Syphilis is a sexually transmitted infection caused by a bacterium referred to as Treponema pallidum (T. pallidum) (Ford, 2014). Although Syphilis can be transmitted through kissing, the conventional ways of spread are generally during oral, vaginal, and anal sex (U.S National Library of Medicine, 2018). It is important to note that Syphilis can also be spread through sharing of objects and tools such as toilet seats and doorknobs through contact (U.S National Library of Medicine, 2018). 

However, the STI can also be passed from mother to child during pregnancy or upon delivery. In cases where the infection is given from the mother to the child, the disease is referred to as congenital syphilis. 

Chanchroid 

Chancroid is a sexually transmitted disease that is caused by a bacteria referred to as Haemophilus ducreyi (Ford, 2014). The infection is common in the developing nations as cases of infection are rarely reported in the US (Healthline, 2017). 

Pathogenesis of bacterial STDs 

Chlamydia 

Chlamydia trachomatis exists in the Chlamydiaceae family (Pommerville & Alcamo, 2016). There is also a single genus Chlamydia which contains three different species with the ability to infect humans: C. pneumonia, C. psittaci, and C. trachomatis . Trachoma, genital infections, conjunctivitis is caused by C. trachomatis while pneumonia is caused by C. pneumonia and C. psittaci (Center for Disease Control and Prevention CDC, 2015). 

Chlamydia trachomatis is an obligate intracellular bacterium with a gram-negative-like cell wall. The bacterium infects the columnar epithelial cells or urethra and often becomes chronic, lasting months to more than a year, if untreated (Center for Disease Control and Prevention CDC, 2015). 

Life cycle 

Chlamydia trachomatis is the life cycle lasts for 48-72 hours (Center for Disease Control and Prevention CDC, 2015). The bacteria live in the host cell and that they survive by replication those in the death of the cell (Pommerville & Alcamo, 2016). The lifecycle of the C. trachomatis is referred below: 

The elementary body (EB), a small infectious particle which is found in secretions, attaches to and enters a cell, such as the inner wall of the cervix or urethral cavity, to replicate (Center for Disease Control and Prevention CDC, 2015). In 48 hours, the EB transforms into a reticulate body (RB), which starts to multiple within an isolated area called an inclusion (Center for Disease Control and Prevention CDC, 2015). In 24 hours, the cell wall bursts and some of the RBs reorganize back to EBs. The EBs are afterward released to cause an infection to the adjacent cells or during transmission from an infected person to another person (Center for Disease Control and Prevention CDC, 2015). 

Gonorrhea 

The bacteria causing agent of gonorrhea id referred to as Neisseria gonorrhoeae (Center for Disease Control and Prevention CDC, 2013). This is an oxidase-positive and gram-negative diplococcus (Center for Disease Control and Prevention CDC, 2013). It utilizes glucose, but not sucrose, maltose, or lactose and infects mucus-secreting epithelial cells (Center for Disease Control and Prevention CDC, 2013). The bacteria, N. gonorrhea, divide by binary fission every 20-30 minutes (Center for Disease Control and Prevention CDC, 2013). 

The bacterium, N. gonorrhea, attaches itself to the various types of epithelial cells through structures located on the surface of gonococci (Center for Disease Control and Prevention CDC, 2013). N. gonorrhea can alter these surfaces structures, which helps the organism to evade a valid host response (Center for Disease Control and Prevention CDC, 2013). 

Syphilis 

Venereal syphilis is caused by Treponema pallidum , a noncultivable, microaerophilic spirochete and obligate human pathogen (Pommerville & Alcamo, 2016). T. pallidum utilizes glycolysis for energy production, has the insufficient biosynthetic capacity and possesses a limited tolerance for environmental stress (Cruz et al., 2012). The transmission of the bacteria occurs in a high percentage of individuals exposed to the primary or secondary syphilitic lesions as it is highly invasive (Cruz et al., 2012). Invasion at the local site occurs shortly after inoculation, while hematogenous dissemination occurs well before the appearance of the chancre. The penetration of the blood-brain barrier by the bacteria occurs commonly in early syphilis and in cases where the patients are not treated (Cruz et al., 2012). This causes the opening up of the next stage of development which is the neurological complications. Clinical manifestations result from the inflammatory responses elicited by spirochetes and spirochetal constituent both locally and systematically (Cruz et al., 2012). 

Chancroid 

Haemophilus ducreyi is the etiological agent of an agent of chancroid and is characterized by the genital mucocutaneous lesions (Buensalido, 2017). The adherence growth of bacteria on the surface of eukaryotic cells and has characteristic genital mucocutaneous lesions (Buensalido, 2017). The adherence and growth of bacteria on the surface of eukaryotic cells, and the production of the cytoxin result in the cell damage that may be responsible for the development of ulcers (Buensalido, 2017). The mechanisms for the protective mechanisms of protective immunity in chancroid are unclear, but both humoral and cell-mediated mechanisms may be involved. 

References  

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