1. Genital Tract Infections
MLAB 2434 – Microbiology
Keri Brophy-Martinez

2. Definitions STI = Sexually Transmitted Infection
STD = Sexually Transmitted Disease
VD = Venereal Disease
After Venus, goddess of love

3. Modes of Transmission Intimate person-person sexual contact
Vaginal intercourse
Oral sex
Anal sex
Mother to child
Pregnancy
Childbirth
Blood products/ tissue transplant

4. 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

5. Chlamydia trachomatis
Lab Diagnosis
Not culturable
Identified by nucleic acid probes

6. 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

7. 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

8. 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

9. Sexually Transmitted Infections (cont’d)
Ulcerative STI’s
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

10. Sexually Transmitted Infections (cont’d)
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

11. Sexually Transmitted Infections (cont’d)
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

12. Sexually Transmitted Infections (cont’d)
Bacterial vaginitis
Signs
Discharge
Vaginal itching
Odor
STD’s
Bacterial vaginosis
Trichomoniasis

13. 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

14. Bacterial Vaginosis Lab diagnosis Wet Prep
Clue cells: exfoliated vaginal epithelial cells covered with GVR and curved GNR’s
Lack of PMN’s
Presence of odor, pH >4.5
Culture
No growth on BAP
V agar: shows as beta hemolytic colonies
Catalase/Oxidase negative

15. 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

16. 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

17. 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

18. 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 Stuart’s or Amie’s (with charcoal)
prevents drying
Culture within 6 hours of collection
Viral culture
Place swab in viral transport media.

19. Genital Cultures Direct Examination Gram stain Wet mount
Performed on male urethral discharge
Examine for bacteria (intra & extra-cellular), PMN’s and other cells
Wet mount
Performed on vaginal discharge
Examine for clue cells, yeast, Trichomonas vaginalis
Examine for PMN’s

20. Genital Bacterial Cultures: Culture 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: hours

21. Genital Bacterial Cultures: Culture Interpretation
Quantitate and identify all potential pathogens
Preliminary report sent out at 24 hours
Hold all plates 72 hours

22. 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
Gram negative rods
Accompanied by an absence of normal flora

23. Genital Tract: Normal Flora
Lactobacillus sp.
Coagulase negative Staphylococcus species
Diptheroids
Anaerobic cocci and gram negative rods
Enterococcus species

24. 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.
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.