- Chlamydia trachomatis is an obligate intracellular, gram-negative bacterium that can cause trachoma (serotypes D-K) as well as urogenital infections (serotypes A-C). Urogenital infections are often asymptomatic but can cause complications like pelvic inflammatory disease and infertility. - Rickettsia rickettsii is a gram-negative bacterium transmitted by ticks that causes Rocky Mountain spotted fever, characterized by a rash and potential fatality if not treated with doxycycline. - Coxiella burnetii is a gram-negative bacterium transmitted via aerosols from infected animals that causes acute flu-like illness or potentially chronic

1. • Gram-negative organisms
• Obligate intracellular bacteria
• unable to produce its own ATP
• Absent peptidoglycan (muramic acid) in the cell wall, which makes beta-lactam antibiotics ineffective
Chlamydia
• Gram stain poorly
• Visible as cytoplasmic inclusion bodies on Giemsa stain or fluorescent
antibody-stained smear

2. • elementary bodies (small and dense bodies that characterize the infectious stage of Chlamydiaceae;
stable in the extracellular environment and almost inactive metabolically)
• reticulate bodies (represent the obligate intracellular, replicative, and metabolically active form of
Chlamydiaceae)
Chlamydia

3. Chlamydia

4. Chlamydia Trachomatis

5. • Serotype A–C
• The most common infectious cause of blindness worldwide
• Africa is the most affected continent.
• Predominantly affects young children and women
• affects more women than men, most likely because of closer contact with
infected children.
Chronic untreated infection can lead to blindness
Chlamydia Trachomatis
Trachoma

6. Trachoma

7. • Serotype D–K
• Transmission
• Sexual intercourse
• Vaginal birth (in which the mother is infected)
• Chlamydial genitourinary infections
• Neonatal conjunctivitis
• Inclusion conjunctivitis
• Infant pneumonia
Chlamydia Trachomatis

8. • The majority of infected individuals are asymptomatic
• (Muco)purulent vaginal discharge; postcoital bleeding
• dysuria; dyspareunia
• Types of infections
• Men: epididymitis, prostatitis
• Women: salpingitis, cervicitis
• Both men and women: urethritis, proctitis
• Chlamydial genitourinary infections
Chlamydia Trachomatis

9. Complications:
• Fitz-Hugh-Curtis syndrome
• Ectopic pregnancy
• Infertility
Fitz-Hugh-Curtis syndrome
• Chlamydial genitourinary infections
Chlamydia Trachomatis
• Pelvic inflammatory disease
• Reactive arthritis (Reiter syndrome)
• urethritis,
• conjunctivitis
• polyarthritis

10. Lymphogranuloma venereum
• serotypes L1–L3
• Primary infection; small, painless genital ulcers (herpetiform) that heal spontaneously within a few days
• Secondary infection; painful swelling of the lymph nodes in the inguinal region (buboes) with abscess
formation (pus discharge)
Chlamydia Trachomatis

11. • Chlamydophila pneumonia
• Atypical pneumonia
• Transmitted by aerosol
• Chlamydophila psittaci
• Psittacosis (Parrot fever)
• Infection from birds
Chlamydial pneumonia

12. Rickettsia Rickettsii
• Tick-borne diseases
• Weakly gram-negative bacteria
• Visible on Giemsa stain
• Invade capillary endothelium → inflammation → small vessel vasculitis

13. • Flu-like symptoms (e.g., fever, headache)
• Rash
• Gastrointestinal symptoms (e.g., nausea, vomiting, abdominal pain)
• Meningitis, focal neurological deficits
• shock and multiorgan dysfunction (e.g., DIC)
Treatment (Doxycycline) should be initiated as soon as
RMSF is suspected, as it can be fatal if not treated early.
Rickettsia Rickettsii
Rocky Mountain spotted fever (RMSF)
Rocky Mountain spotted fever rash

14. • Blanching maculopapular rash: begins on the wrists and ankles
• Spreads to the trunk, palms, and soles
• Ankle and/or wrist swelling
Rickettsia Rickettsii
Rocky Mountain spotted fever (RMSF)

15. Rickettsia typhi
Endemic typhus
• Transmission: rat and cat fleas
• Clinical features
• Maculopapular or petechial rash erupts on the trunk; and spreads to
the extremities (palms and soles are spared).
• Treatment: doxycycline

16. Rickettsia prowazekii
• Transmission: body louse
• Clinical features
• Abrupt onset of fever, severe headache, malaise, myalgia, abdominal pain,
nausea, cough
• After 4–5 days: maculopapular or petechial rash that spreads from the
trunk
• Treatment: doxycycline
Epidemic typhus

17. • Tick-borne illness
• Obligate intracellular bacteria
• Leukopenia
• thrombocytopenia
• elevated
• serum transaminases
• Treatment: Doxycycline
Ehrlichiosis
Ehrlichia

18. Coxiella burnetii
• primary reservoirs are cattle, sheep, and goats
• Direct infection (no vector transmission)
• Inhalation of spore-containing aerosols from the amniotic fluid
• Infection is reactivated during pregnancy and large concentrations are then found in the
placenta as well. C. burnetii is released as an aerosol during birth.

19. Coxiella burnetii
Flu-like symptoms
High-grade fever, chills, malaise, myalgia
Headache
Atypical pneumonia: generally mild with nonproductive cough and fever
others
Acute Q fever

20. Chronic Q fever
• Low-grade fever
• Night sweats, fatigue
• Weight loss
• Swelling arms/legs
• Endocarditis:
• chronic Q-fever is the most common cause of culture-negative endocarditis.
Coxiella burnetii