Genital Tract Infections

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Genital Tract Infections

• MLAB 2434 Microbiology
• Keri Brophy-Martinez

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Definitions

• STI Sexually Transmitted Infection
• STD Sexually Transmitted Disease
• VD Venereal Disease
• After Venus, goddess of love

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Modes of Transmission

• Intimate person-person sexual contact
• Vaginal intercourse
• Oral sex
• Anal sex
• Mother to child
• Pregnancy
• Childbirth
• Blood products/ tissue transplant

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Sexually Transmitted Infections

• Genital Chlamydiosis
• Chlamydia trachomatis
• Obligate intracellular bacterium
• Most common bacterial STD
• Symptoms
• Male urethritis, discharge
• Female Usually asymptomatic can progress to PID

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Chlamydia trachomatis

• Lab Diagnosis
• Not culturable
• Identified by nucleic acid probes

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Sexually Transmitted Infections

• Neisseria gonorrhoeae
• Infects columnar epithelial cells of the GU tract
• Incubation period 2-7 days
• Can spread in blood, producing rash on
  extremities and arthritis in joints

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Neisseria gonorrhoeae

• Symptoms
• Male urethral inflammation with dysuria, pyuria,
  urethral discharge
• Female asymptomatic can lead to PID
• Treatment
• Cephalosporin antibiotic class
• Cefixime or ceftriaxone with doxycycline

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Neisseria gonorrhoeae

• Laboratory Diagnosis
• Typical GN dc, kidney- bean shape
• Gram stain significant in males, not in females(
  due to other GN normal flora)
• Identify via CTA sugars or other rapid kits
• Market using DNA probes instead of culture

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Sexually Transmitted Infections (contd)

• Ulcerative STIs
• Syphilis Treponema pallidum
• Incubation period of 1-90 days
• Chancre development at site of inoculation,
  full-body rash, potential to affect the CNS
• Can not be cultured DFA or serology testing
  (RPR) used

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Sexually Transmitted Infections (contd)

• Chancroid Haemophilus ducreyi
• Seen in underdeveloped countries
• Incubation period 4-7 days after exposure
• Erythematous papule develops into a pustule which
  ruptures to form an ulcer. Ulcer usually found
  on external genitalia
• Lab diagnosis
• Direct smear (school of fish) and culture of
  ulcer
• Oxidase positive catalase negative

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Sexually Transmitted Infections (contd)

• Genital Herpes- Herpes Simplex Virus
• HSV-1 fever blisters/ cold sores
• HSV-2 genital herpes
• Virus is shed in the absence of symptoms
• Transmitted by sexual contact with secretions
  from infected sites
• Incubation period 1-26 days after exposure
• Lab diagnosis
• Viral isolation-cheap
• Molecular testing- improved sensitivity TAT

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Sexually Transmitted Infections (contd)

• Bacterial vaginitis
• Signs
• Discharge
• Vaginal itching
• Odor
• STDs
• Bacterial vaginosis
• Trichomoniasis

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Bacterial vaginosis

• Loss of normal vaginal flora
• Mobiluncus, Mycoplasma hominis, and Gardnerella
  vaginalis take over
• pH increases causing a fish-like odor
• Bedside diagnosis
• pH- greater than 4.5
• Whiff test-addition of KOH, smell for a fishy odor

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Bacterial Vaginosis

• Lab diagnosis
• Wet Prep
• Clue cells exfoliated vaginal epithelial cells
  covered with GVR and curved GNRs
• Lack of PMNs
• Presence of odor, pH gt4.5
• Culture
• No growth on BAP
• V agar shows as beta hemolytic colonies
• Catalase/Oxidase negative

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Trichomonas vaginalis

• Flagellated, urogential parasite
• Symptoms
• Itching
• Burning
• Yellow-green frothy discharge
• Foul-smelling odor
• Lab Diagnosis
• Wet Prep
• Observance of moving parasites in vaginal
  discharge

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Human Papilloma Virus (HPV)

• Common STD in individuals under 24
• Skin- skin transmission
• Asymptomatic
• Self-limiting
• Associated with genital warts and cervical cell
  dysplasias and cancers

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Human Immunodeficiency Virus (HIV)

• Systemic illness
• Transmission via sexual contact, exposure to
  blood or body fluids
• Virus attacks the CD4 helper T-cells
• Increased potential for opportunistic pathogens
• Symptoms include
• fever, malaise, lymphadenopathy, skin rash
• Lab Diagnosis
• HIV-1 antibody test- screen
• Western blot/immunofluorescence- confirmatory

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Genital Bacterial Cultures Specimen
Collection, Transport and Handling

• Specimen types
• Urethral discharge
• Cervical/ vaginal
• Throat
• Anus
• Specimen collection, transport and handling
• Cotton, rayon or dacron swabs
• Isolation of gonococci
• Place in modified Stuarts or Amies (with
  charcoal)
• prevents drying
• Culture within 6 hours of collection
• Viral culture
• Place swab in viral transport media.

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Genital Cultures

• Direct Examination
• Gram stain
• Performed on male urethral discharge
• Examine for bacteria (intra extra-cellular),
  PMNs and other cells
• Wet mount
• Performed on vaginal discharge
• Examine for clue cells, yeast, Trichomonas
  vaginalis
• Examine for PMNs

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Genital Bacterial CulturesCulture Set-Up

• Examples of media to inoculate
• BAP
• MAC
• Chocolate
• CNA
• V- agar
• Thayer-martin, Modified Thayer-Martin, GC-Lect
• Lim broth
• Incubate media
• Temperature 35OC
• Atmosphere CO2
• Time 18-24 hours

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Genital Bacterial CulturesCulture
Interpretation

• Quantitate and identify all potential pathogens
• Preliminary report sent out at 24 hours
• Hold all plates 72 hours

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Genital Tract Pathogens

• Neisseria gonorrhoeae
• Hemophilus ducreyi
• Gardnerella vaginalis
• Trichomonas vaginalis
• Beta-hemolytic Streptococci Groups A and B
• Listeria species
• Staphylococcus aureus
• In predominant numbers
• Candida/yeast species
• In predominant numbers
• Gram negative rods
• Accompanied by an absence of normal flora

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Genital TractNormal Flora

• Lactobacillus sp.
• Coagulase negative Staphylococcus species
• Diptheroids
• Anaerobic cocci and gram negative rods
• Enterococcus species

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References

• Hook, E. W. (2012, July). A new look at genital
  herpes the critical role of the laboratory in
  diagnosis and management. Medical Laboratory
  Observer, 44(7), 8-12.
• http//www.atsu.edu/faculty/chamberlain/golden2000
  /case5.htm
• http//tiny.cc/kcpyhw
• Kiser, K. M., Payne, W. C., Taff, T. A. (2011).
  Clinical Laboratory Microbiology A Practical
  Approach . Upper Saddle River, NJ Pearson
  Education.
• Mahon, C. R., Lehman, D. C., Manuselis, G.
  (2011). Textbook of Diagnostic Microbiology (4th
  ed.). Maryland Heights, MO Saunders.