Clinical Significance of Neisseria gonorrhoeae

Gonorrhea is the second most prevalent sexuality transmitted disease of bacterial etiology (Hay et al 2000). Infections involving Neisseria gonorrhoeae may either present as symptomatic or asymptomatic or cause cervicitis, urethritis, proctitis, conjuctivitis or Bartholinitis. In men, gonorrhoeae infections may cause complications such as prostatitis, epididymis and seminal vesiculitis. With regard to homosexuals, pharyngitis and rectal infection may also occur.

Among females, many Neisseria gonorrhoeae infections are asymptomatic and include complications in the rectum and urethra. In most cases these complications may coexist with cervical infection. Complications may also include pelvic pain, pelvic inflammatory disease, ectopic pregnancy, infertility, premature labor, spontaneous abortion, chorioamnionitis, and infections of the neonate as well as Fitz-Hugh Curtis syndrome (Gaydos 1998). Neisseria gonorrhoeae colonize the genitourinary tract or rectum mucous membranes.

After colonization they cause a localized infection that is characterized with the production of pus. In some cases these organisms invade tissues, cause chronic inflammation and fibrosis. Since infections in females are mainly asymptomatic, they act as infection reservoirs for the maintenance and transmission of the disease. It is prudent to note that more than a single sexuality transmitted infection can be acquired or transmitted at any given time. Infections that are localized in the genitourinary tract are more acute and much easier to diagnose among males.

Symptomatically, the patient presents with a yellow and purulent urethral discharge as well as experiences of pain during urinating. On the other hand, in females where the infection is localized in the endocervix extending to the urethra and the vagina, the most common symptom is a greenish yellow cervical discharge. In most cases intermenstrual bleeding accompanies this cervical discharge. Progression to the uterus causes salpingitis, pelvic inflammatory disease and fibrosis.

Statistics show that about 20% of women diagnosed with gonococcal salpingitis may develop infertility as a result of tubal scarring. As aforementioned, rectal infections are mainly concentrated among homosexuals. Symptomatically, the infection presents as painful defecation, constipation and purulent discharge. Pharyngitis only develops in cases where there is oral-genital discharge. A purulent exudate may be observed and pharyngitis mimics streptococcal sore throat or a mild viral infection.

Ophthalmia neonaratum; an infection of the newborn that is caused by the passage of the mother’s infection to the newborn during childbirth. This infection of the conjuctivial sac or rather acute conjuctivitis, if left untreated may result to blindness. Usually treatment with erythromycin serves not only to eradicate Neisseria gonorrhoeae but also Clamydia trachomatis. Gonococcal conjuctivitis is not only limited to the newborn as it can also occur in adults (Harvey et al 2006).

Usually strains of N. gonorrhoeae possess a limited ability to multiply in the hosts’ bloodstream. Thus, cases of bacteremia are extremely rare. This is a distinguishing feature between N. gonorrhoeae and N. meningitidis which rapidly multiply in the host’s bloodstream. For stains that invade the bloodstream and lead to the development of bacteremia, they cause painful purulent arthritis, fever and small scattered pustules on the skin. These pustules have erythematous bases and may develop necrosis.

Dissemination of infection is prevalent in both sexes, but more prevalent in females during menses and pregnancy (Harvey et al 2006). Identification, Isolation and Classification of Neisseria gonorrhoeae Since, N. gonorrhoeae does not multiply and persist in the bloodstream for the quantity and duration necessary for a conclusive identification and isolation, laboratories prefer, urine or urethral exudates as the most reliable samples for analysis.

From male urethral exudate samples, the presence of numerous neutrophils with gram positive diplococci in the smear constitutes a provisional diagnosis of gonorrhea. However, to make a positive diagnosis as regards female samples or male samples other than urethral exudates(for instance joint fluid, blood and skin lesions), culturing is necessary. Prior to the acquisition of specimens for the isolation of N. gonorrhoeae it should be taken into account that the bacteria have the capacity to infect several sites simultaneously.

This implies that collection is dependent on the patterns of sexual practices. In cases where gonococci and meningococci have to be transported over long distances hence delay of isolation it would be appropriate to submit an unstained smear this is to eliminate the inhibitory effect. Apart from swab collections, urine centrifugates can be used as they are more recommended for gonococcal culture. Samples are incubated in culture medium at a temperature of 35-37°C, CO2 supplementation and added humidity.

In most cases, a plain candle non toxic jar is adequate or an incubation chamber for larger laboratories. Both the selective and non selective media may be used in the analysis of samples. However, for gonococci, a non selective media my require enrichment with co-factors, amino acids and additives like Isovitalex or the equivalent. These supplements ensure the growth of fastidious auxotrophs. Selective media usually contain the latter’s solid base infused with colistin, trimethoprin, vancomycin and an antifungal agent.

The most common selective medium in use currently is the Martin-Lewis, New York City media and the modified Thayer-Martin medium. Culturing usually takes at most 72 hrs. Since some gonococci such as auxotrophs are susceptible to the antibiotic vancomycin, it is recommended that in the isolation of gonococci the benefit of another selective medium should be exploited (Cimolai 2000). Based on either oxidase test or colony morphology in selective media, the mere demonstration of growth under all the essentials for growth is enough to raise the concern for N.

gonorrhoeae. The production of acid in CTA sugars (glucose, fructose, lactose, sucrose and maltose) confirms identification. Alternatively, immunoflourescence using specific species polyclonal or monoclonal antibodies interpreted through confirmatory agglutination reactions or DNA probes can be used to definitively identify and isolate N. gonorrhoeae (Coghill & Young 1987; Cimolai 2000). DNA probing is the current identification methodology owing to the problems with gonorrhea. This method involves direct genetic detection using commercial investigative DNA probes.

Based on the Interbantional Statistical Classification of Diseases and Health Problems(commonly abbreviated as ICD), disease are classified and allocated codes that are descriptive of a variety of signs, symptoms, complaints, abnormal findings, the social circumstances as well as the external causes of disease or injury. Classified under ICD-10 code, gonorrhea lies at Chapter XIV, Block N00-N99 which is a classification of diseases of the genitourinary system, and gonorrhea has the code A54. (WHO). In the list of ICD-9 it is coded under 580-629: Diseases of the genitourinary system, as 098.

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