Case Study of Sexually Transmitted Infection (STI) Facts Medical Essay; In Case study 5, A male, 24 years of age presents to the STI clinic. He complains of a burning and sore sensation upon urination, along with discharge from his penis that has a mucopurulent consistency and is green-yellow. In the preceding two weeks, he has had unprotected sex with numerous partners.
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Laboratory tests; A penile/urethral swab is taken from the male and is inoculated onto NYC agar and chocolate agar. The plates are incubated at 37˚C in CO2 at the clinic and later that evening is transported to the microbiology laboratory. A Gram stain is carried out on a smear of the penile discharge. The patient is also screened for other STI’s and is interviewed about contact tracing his sexual partners.
Results; The following are the results obtained for the organisms growing on the chocolate agar and the organism growing on the NYC agar. Both agars existed incubated in CO2 at 37˚C. Two organisms, A and B, were growing on the chocolate agar. Organism B was growing on both agars. This organism existed identified as Neisseria gonorrhoeae. The preliminary identification of organism A existed not obtained. Neisseria gonorrhoeae is the causative pathogen of gonorrhea, a sexually transmitted infection facts that exist characterized by a pus-filled infection of the surfaces of the mucous membranes of the throat, eye, vagina, and urethra in males and females.
This pathogen can spread through direct sexual contact or vertical transmission from mother to baby during birth. Symptoms of this bacteria in males include painful urination and urethral discharge, while females present with increased vaginal discharge. Usually, females infected with this pathogen present as asymptomatic and are the biggest reservoir of this sexually transmitted infection facts.
Catalase: + = positive for the enzyme catalase – bubbles produced.
= negative for the enzyme catalase – no bubbles produced
Oxidase: + = positive for the enzyme oxidase – purple color formed
= negative for the enzyme oxidase – no color formed
From the clinical details given in Case study 5 and from the basic characterization tests; it is evident that the causative pathogen of the patient’s dysuria and penile discharge; and the organism that was growing as organism B on chocolate agar and growing on the NYC agar is Neisseria gonorrhoeae.
Numerous further tests could carry out to confirm this causative pathogen Neisseria gonorrhoeae that the patient in this case study infects with. This pathogen should confirm using two different methods of detection as biochemical; such as the API NH strip for Neisseria and Haemophilus species and molecular and serological testing. Such tests include the Nucleic Acid Hybridization Test (NAAT) that utilizes a DNA probe that exists labeled with a chemiluminescent tag and exists targeted to a region of the 16s rRNA of the Neisseria gonorrhoeae pathogen that mixed with the patient’s sample.
This assay is based on the hybridization of nucleic acids. In the patient’s sample, if the pathogen is present, rRNA released from Neisseria gonorrhoeae will hybridize with the probe DNA. The probe that does not hybridize stands removed. The DNA: RNA hybrids luminescence intensity exists then measured. Samples used for this testing are endocervical and urethral swabs. According to the HPSC, NAAT testing is the standard test for the laboratory detection of Neisseria gonorrhoeae. The enzyme tube test, Gonocheck II can differentiate between the various Neisseria species; such as Neisseria meningitides, Neisseria lactamica, and Neisseria gonorrhea.
Essay Part 01;
Specimens used for this test stand well-isolated colonies from either Modified Thayer Martin or chocolate agars. Enzymes produced by the bacteria act on colorless substrates to produce colored end products. Neisseria meningitidis produces a yellow end product. Neisseria gonorrhoeae produces three enzymes – gammaglutamylaminopeptidase, hydroxyprolyaminopeptidase, and beta-galactosidase and produce a red-pink colored end product, confirming this pathogen (CDC, 2018).
The GeneXpert CT/NG System by Cepheid is a real-time PCR NAAT platform that allows sample preparation, amplification, and detection of Neisseria gonorrhoeae from patient urine samples, male urethral swabs, and female vaginal and endocervical swabs in 90 minutes. The Abbott RealTime CT/NG utilizes RT-PCR and a fluorescent-labeled oligonucleotide probe that allows for the direct, real-time, fluorescent, qualitative detection of the genomic DNA of Neisseria gonorrhoeae and plasmid DNA of Chlamydia trachomatis from patient urine samples, male urethral swabs, and female vaginal and endocervical swabs.
Neisseria gonorrhoeae possesses a wide abundance of virulence factors that enable it to efficiently establish infection; and adapt to its host’s environment, as it did in this patient in the case study. The entry site of this bacteria in males is the urethral cells of the penis and the vagina in females. This pathogen mainly infects the epithelia of the urogenital tract and infects areas; such as the rectal mucosa, pharynx, and conjunctiva less commonly. Neisseria gonorrhoeae, with its repertoire of adhesion molecules, attach to the cuboidal and columnar epithelial cells present in the urethra, pharynx, endocervix, and anorectal region.
Essay Part 02;
Such adherence molecules include pili, porin proteins – Opa and PI, and type IV fimbriae. These adhesion molecules bind to host carcinoembryonic antigen cell adhesion molecules (CEACAM) receptors present on epithelial cells. Once attached to these receptors, the pathogen then rapidly proliferates and spreads up through the urethra in males; and the cervix to the fallopian tubes in females where the infection and healing processes cause fibrosis, blockage, and damage to the tubes. These adhesion molecules can evade existing removed by vaginal discharge or urine.
The pili and fimbriae facilitate attachment to the mucosal epithelium and the pili protein genes possess hypervariable; and constant regions that enable the pathogen to exhibit antigenic variation by recombination of its surface antigens. This proves difficult in developing a vaccine for this bacteria and also for the production of host antibodies; that is only effective for a short duration and so, are not protective against this bacteria. Pili also enable twitching motility that allows the bacteria to ascend the mucous lined surfaces. Porin protein (PI) is responsible for forming pores in the host cell membrane and induces apoptosis in the epithelial cells causing the shed of epithelial cells and fallopian tube damage in females.
Essay Part 03;
However, in a study carried out by using Chang epithelial cells, an anti-apoptotic role of porin proteins existed hypothesized. It existed found that enhancing the survival of epithelial cells of the urethra could allow the bacteria to multiply within an intracellular environment that protects and thus, enhance the colonization of Neisseria gonorrhoeae. PI also allows the bacteria to survive following apoptosis. Neisseria gonorrhoeae also possesses a lipo-oligosaccharide layer (LOS) that exhibits endotoxin activity by inducing inflammation. A pelvic inflammatory disease that can result in fallopian tube infection; and infertility caused by the shedding of the LOS that initiates local inflammatory injury.
The LOS can evade the activation of the complement cascade by concealing itself with host sialic acid, rendering it unrecognizable by the host immune system. Opa proteins present on the surface of Neisseria gonorrhoeae, bind to the CEACAM family of adhesion receptors present on neutrophils, epithelial cells, and B and T lymphocytes, facilitating the activation of the adaptive and innate immune responses upon epithelial cell infection. TNF- α, a cytokine released during the host innate immune response is pro-inflammatory and has a profoundly damaging effect on the host epithelial cells such as the fallopian tubes; This cytokine prompts the production of phospholipases and proteases, inducing excess inflammation and damage.
Essay Part 04;
Neisseria gonorrhoeae contain the enzyme IgA protease at its core. This is responsible for breaking down the host IgA1 antibodies found in mucosal membranes that have an immune function in protecting against infections in the mucous membranes. This bacteria also possess a capsule that allows them to resist opsonization and phagocytosis; as it is similar in composition to that of the connective tissue of the host. Thus, this enables the bacteria to multiply, survive and spread within the host to carry out further infection and damage. All of these virulence factors culminated to initiate infection in the male patient in this case study to cause his burning and sore sensation while urinating and his purulent penile discharge.
If gonorrhea does not treat, disseminated Gonococcal Infection (DGI) occurs. This is due to Neisseria gonorrhoeae spreading systemically to other parts of the body via the bloodstream, causing joint pain and arthritis, and lesions on the skin, and endocarditis may also result from DGI but this is rare. DGI is more common in females due to them more frequently being asymptomatic. Further investigation that could carry out for this patient includes contact tracing all of his previous sexual partners in the past two weeks and notifying them of his infection.
Essay Part 05;
The HPSC international guidelines for gonorrhea infections recommend that all male patients; who have a urethral infection that is symptomatic must notify all of their sexual partners of the previous two weeks or if longer; their last partner This ensures that his previous sexual partners are made aware of his infection; as they too may infect and may not be displaying symptoms (asymptomatic). His previous partners will also undergo a full STI screen to establish whether they infect with gonorrhea or other sexually transmitted infection facts.
Contact tracing reduces transmission of Neisseria gonorrhoeae and its reinfection; while also informing and aiding individuals and healthcare workers in the understanding of the patterns of transmission within communities. In Ireland, gonorrhea is a notifiable disease under the Infectious Disease Regulations as this pathogen can have consequences later in life such as infertility.
In 2017, there were 2249 notified cases of gonorrhea in Ireland; causing it to become the second most commonly encountered STI in Ireland. This pathogen has an incidence rate in Ireland of 47.2 per 100,000 population. However, these figures believe to underestimate as 55% of males and 86% of females suffering from gonorrhea infections are asymptomatic and so, the actual figures believe to be a lot higher.