Transcript Chapter 16 - Enterobacteriaceae

Genital Tract
Infections
MLAB 2434 – Microbiology
Keri Brophy-Martinez
Definitions
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STI = Sexually Transmitted Infection
STD = Sexually Transmitted Disease
VD = Venereal Disease
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After Venus, goddess of love
Modes of Transmission
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Intimate person-person sexual
contact
Vaginal intercourse
 Oral sex
 Anal sex
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Mother to child
Pregnancy
 Childbirth
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Blood products/ tissue transplant
Sexually Transmitted
Infections
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Genital Chlamydiosis
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Chlamydia trachomatis
• Obligate intracellular bacterium
Most common bacterial STD
 Symptoms
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• Male: urethritis, discharge
• Female: Usually asymptomatic; can
progress to PID
Chlamydia trachomatis
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Lab Diagnosis
Not culturable
 Identified by nucleic acid probes
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Sexually Transmitted
Infections
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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
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Symptoms
Male: urethral inflammation with
dysuria, pyuria, urethral discharge
 Female: asymptomatic; can lead to
PID
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Treatment
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Cephalosporin antibiotic class
• Cefixime or ceftriaxone with
doxycycline
Neisseria gonorrhoeae
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Laboratory Diagnosis
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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
Sexually Transmitted
Infections (cont’d)
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Ulcerative STI’s
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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
Sexually Transmitted
Infections (cont’d)
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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
Sexually Transmitted
Infections (cont’d)
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Genital Herpes- Herpes Simplex Virus
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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
Sexually Transmitted
Infections (cont’d)
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Bacterial vaginitis
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Signs
• Discharge
• Vaginal itching
• Odor
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STD’s
• Bacterial vaginosis
• Trichomoniasis
Bacterial vaginosis
Loss of normal vaginal flora
 Mobiluncus, Mycoplasma hominis,
and Gardnerella vaginalis take over
 pH increases causing a fish-like
odor
 Bedside diagnosis
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pH- greater than 4.5
 Whiff test-addition of KOH, smell
for a fishy odor
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Bacterial Vaginosis
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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
Trichomonas vaginalis
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Flagellated, urogential parasite
Symptoms
 Itching
 Burning
 Yellow-green frothy discharge
 Foul-smelling odor
Lab Diagnosis
 Wet Prep
• Observance of moving parasites in
vaginal discharge
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)
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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:
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fever, malaise, lymphadenopathy, skin rash
Lab Diagnosis
 HIV-1 antibody test- screen
 Western blot/immunofluorescence- confirmatory
Genital Bacterial Cultures:
Specimen Collection, Transport and
Handling
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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.
Genital Cultures
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Direct Examination
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Gram stain
• Performed on male urethral discharge
• Examine for bacteria (intra & extracellular), PMN’s and other cells
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Wet mount
• Performed on vaginal discharge
• Examine for clue cells, yeast, Trichomonas
vaginalis
• Examine for PMN’s
Genital Bacterial Cultures:
Culture Set-Up
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Examples of media to inoculate
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Incubate media
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BAP
MAC
Chocolate
CNA
V- agar
Thayer-martin, Modified Thayer-Martin, GCLect
• Lim broth
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Temperature: 35OC
Atmosphere: CO2
Time: 18-24 hours
Genital Bacterial Cultures:
Culture 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
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Neisseria gonorrhoeae
Hemophilus ducreyi
Gardnerella vaginalis
Trichomonas vaginalis
Beta-hemolytic Streptococci Groups A and B
Listeria species
Staphylococcus aureus
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Candida/yeast species
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Gram negative rods
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In predominant numbers
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In predominant numbers
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Accompanied by an absence of normal flora
Genital Tract:
Normal Flora
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Lactobacillus sp.
Coagulase negative Staphylococcus
species
Diptheroids
Anaerobic cocci and gram negative
rods
Enterococcus species
References
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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/cas
e5.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.