Flashcards in Exam #6: Other Bacterial GU Infections Deck (41):
Describe the normal microbiota of the vagina. How does the normal flora change throughout life?
Hormonal influences throughout life causes variation in the normal flora
- Childbearing years= Lactobacillus
- Young girls & post-menopausal= lower prevalence of Lactobacilli
List the characteristics of Lactobacillus. What is unique about Lactobacillus?
- Gram (+) rod
- Mircoaerophilic or anaerobic
*Note that Lactobacilli CANNOT grow in the presence of urine i.e. does NOT cause UTI
What is the pH of the vagina? Why?
pH is 4-5
- Glycogen is metabolized to lactic acid by lactobacilli
What is the outcome of the relatively low pH of the vagina?
Optimal growth of Lactobacilli & inhibition of growth of other bacteria
How does hysterectomy or removal of the cervix change the normal microbiota of the vagina?
Hysterectomy leads to an increase in Bacteroides fragilis
- E.coli & Enterococcus species are also found in culture from women who develop pelvic infections status post hysterectomy
What is bacterial vaginosis?
A complex & poorly understood syndrome that causes an overgrowth of anaerobic species & reduction of Lactobacillus
Anaerobic species include: Gardnerella vaginalis, Ureaplasma urealyticum, Mobiluncus species, Mycoplasma hominis, and Prevotella species
What are the symptoms of BV?
What are the risk factors for BV?
Sex during menses
New or multiple sex partners
Note that despite its association with intercourse, Bacterial Vaginosis is NOT an STD.
What is the typical discharge of BV?
White or grey with a "milk-like" appearance
What are the four amsel criteria for the diagnosis of BV? How many must be met for the diagnosis?
2) Clue cells
3) Whiff Test
4) pH greater than 4.5 (lactobacilli absent)
What is a clue cell?
Vaginal epithelial cell that appears granular & is coated with coccobacillary organisms
*Seen in Bacterial Vaginosis
What is the whiff test?
- KOH addition to sample of vaginal discharge
- Smells fishy b/c of the release of volatile amines
What is the Nugent score?
Numerical score based on semi-quantization of:
1) large gram(+) rods
2) small Gram-variable rods
3) curved Gram-variable rods
0-3 is normal
4-6 indicates mixed morphotypes
7-10 demonstrates an absence of lactobacilli
What are the complications of BV?
1) Increased susceptibility to STDs including HIV
2) Passage of HIV to partner
3) Increased development of infection following surgical procedures
4) Increased risk of pregnancy complications e.g. preterm delivery, miscarriage, & infection after delivery
How is BV treated?
What is vulvovaginal candidiasis?
I.e. common fungal infection (Candida albicans overgrowth)
Describe the discharge of a yeast infection.
White vaginal discharge
What is complicated VVC?
- Recurrent (>4 per year) or severe VVC
- Non-albicans candidiasis
Or, patient who has:
- Uncontrolled DM
Describe the morphological features of candida albicans.
- Oval yeast forms
- Buds, pseudohyphae, & hyphae
What is a positive germ tube test indicative of?
When is VVC infection most common? What are other risk factors for VVC development?
- Oral contraceptives
- Systemic corticosteroids
- HIV infection
What else can candida albicans cause?
How is candidia albicans diagnosed?
- Microscopic examination with 10% KOH
- "Nickerson medium"
- Germ tube test
How is VVC treated?
Topical azole (uncomplicated)
Topical + oral fluconazole (complicated)
What is Trichomoniasis?
The most common curable STD causing vaginitis
What are the symptoms of Trichomoniasis?
"Yellow-green, frothy, foul-smelling, discharge"
Can men get Trichomoniasis?
Yes but they are asymptomatic; men serve as carriers of the disease
What causes Trichomoniasis?
What is Trichomonas vaginalis? List the characteristics of Trichomonas vaginalis.
Small, pear-shaped protozoa
- 4 anterior flagella & undulating membrane that make it mobile
- Contains a rigid axostyle involved in attachment
- Exists ONLY as a TROPHOZOITE
Describe the pathogenesis of Trichomonas vaginalis.
Trichomonas vaginalis causes destruction of epithelial cells in the GU tract, leading to neutrophil influx & petechial hemorrhages
*Note that one does NOT develop immunity*
How is Trichomonas vaginalis diagnosed?
Detection of swimming T.vaginalis in discharge
How is Trichomonas vaginalis treated?
Metronidazole (treat BOTH partners)
What causes TSS?
TSST-1 producing strains of S. aureus that multiply rapidly in hyperabsorbant tampons
List the characteristics of S. aureus.
Gram (+) cocci
How are the clinical manifestations of TSS categorized?
Toxin mediated (intoxication)
Describe the mechanism of action of TSST-1.
TSST-1 penetrates the mucosal barrier & is responsible for systemic effects of TSS
- Superantigen that stimulates T-cell activation & release of cytokines
- Links MHC-II to TCR indiscriminately
- Massive cytokine release= symyptoms
What cytokines mediate TSS?
TNF-a (shock & hypotension)
IL-2 (further proliferation of T-cells)
What are the presenting symptoms of TSS?
*Characteristic rash that looks like a sunburn & sloughing off of skin called "erythroderma"
How is TSS diagnosed?
Systolic BP less than 90
Note that TSST will be detected in the vagina but NOT blood
How is TSS treated?
Administer B-lactamase resistant PCN or vancomycin