Chlamydia

INTRODUCTION:
  • Obligate gram -ve intracellular bacterial parasite unable to grow in cell free media (against Koch's postulates)
  • Also called PLT agent (Psittacosis, LGV, Trachoma)
  • Lacks enzyme for ETC and requires enzyme from the host and hence called Energy parasites
  • They do not have peptidoglycan cell wall.
  • Hence drugs that act on cell wall like penicillin derivatives are ineffective. Erythromycin, tetracycline and azhithromycin are effective
  • Stains - Giemsa, Castenedo, Ma chiavello
  • Most common organism associated with reactive arthritis is Chlamydia
TYPES:
  • Occur in two forms
  • Elementary body - extracellular infective form
  • Reticulate body - intracellular growing and replicative form
CHLAMYDIA TRACHOMATIS
  • Chlamydia trachomatis occurs in two forms during its life cycle(biphasic)
  • The extracellular form is a small, hardy infectious form metabolically inactive and is known as the elementary body.
  • A larger fragile intracellular replicative form termed the reticulate body (RB).
  • It enters the cell in an endocytotic vacuole & Only inside cell, it transforms itself into a reticulate body, which is its active replicative form.
  • The ability to inhibit lysosomal fusion is unique to chlamydia and enables the EB to survive in a vesicle referred to as an basophilic inclusion body.
  • C trachomatis also inhibits apoptosis of epithelial cells, thus enabling completion of its replicative cycle.
  • Reticulate body divides by binary fission
  • Inside the cell Chlamydia trachomatis evades phagolysome
  • It is the most common cause of nongonococcal urethritis (NGU) and post gonococcal urethritis (PGU)
Infection Of Eye:
  • Chlamydia trachomatis (serotypes A, B, and C) causes a conjunctival and corneal infection
  • The lesions begin with formation of lymphoid follicles in the conjunctiva
  • In established trachoma, there may be superior epithelial keratitis, sub epithelial keratitis, pannus, or superior limbal follicles, and ultimately the pathognomonic cicatricial remains of these follicles, known as Herbert's pits—small depressions covered by epithelium at the limbo corneal junction.
  • The associated pannus is a fibrovascular membrane arising from the limbus, with vascular loops extending onto the cornea. All of the signs of trachoma are more severe in the upper than in the lower conjunctiva and cornea.
  • It causes Scarring of the cornea leading to blindnes
  • With disease progression, there is tissue necrosis, granulation tissue deposition, and scar formation, leading to lacrimal duct obstruction and distortion of the eyelids. With the loss of an adequate tear system, the cornea becomes vulnerable to dehydration and opacification.
  • Also, the vigorous inflammatory response can directly involve the cornea, with resulting opacity.
Nongonococcal Urethritis:
  • Diagnosed by documentation of a leukocytic urethral exudate and by exclusion of gonorrhea by Gram's staining or culture.
  • Symptoms include urethral discharge (often whitish and mucoid rather than frankly purulent), dysuria, and urethral itching.
  • Physical examination may reveal meatal erythema and tenderness as well as a urethral exudate.
  • Asymptomatic chlamydial urethritis has been demonstrated in 5–10% of sexually active male adolescents screened at school-based clinics or community centers.
  • Such patients generally have pyuria (15 leukocytes per 400x microscopic field in the sediment of first-void urine), a positive leukocyte esterase test, or an increased number of leukocytes on a Gram-stained smear prepared from a urogenital swab.
Inclusion conjunctivitis
  • Serotypes D to K
  • Neonate - Inclusion blenorrhea
  • Adult - swimming pool disease
Genital chlamydiasis
  • Serotypes D to K
  • Mostly asympotmatic
  • MCC of nongonococcal and postgonococcal urethritis
  • Men: urethritis (non-gonococcal) epididymitis, proctitis, conjunctivitis, Reiter's syndrome (triad of recurrent conjunctivitis, polyarthritis and urethritis in men or cervicitis in women)
  • Women: acute urethral syndrome, bartholinitis, mucopurulent cervicitis, endometritis, salphingitis(infertility), pelvic inflammatory disease, conjunctivitis, perihepatitis (Fitz-Hugh-Curtis syndrome) and Reiter's syndrome
  • Gram stained smears of urogenital exudates show significant number of neutrophils
  • Nucleic acid amplification tests (NAAT)- tests of choice to diagnose genital C trachomatis infections

C.trachomatis A,B,Ba,C Endemic blinding trachoma
C.trachomatis D,E,F,G,H,I,J,K Inclusion conjunctivitis
Genital chlarnydiasis
Infant pneumonia
C.trachomatis L1 ,L2,L3 Lymphogranuloma venereum
Hemorrhagic proctitis
C.psittaci Many serotypes Psittacosis(parrot fever, parrot disease,
or ornithosis)
C.pneumoniae Only one serotype Acute respiratory disease

Trait C.trachomatis C.pneumonia C.psittaci
Inclusionbody Trachoma - Halberstaedter-Prowazek
(HP)bodies
LGV - Migayawa's granulocorpuscles
Round dense Levinthal-ColeLillie (LCL)bodies
Glycogen ininclusions + - -
Sulfonamidesensitivity + - -
Transmission Person to personMother to infant Air bornePerson to person Air borne (birdexcreta to human)

  • Lymphogranuloma venereum (LGV)
  • MC presenting symptom painful inguinal lymphadenopathy
  • Primary lesion: small painless papulovesicular lesion on external genitalia
  • Secondary stage: lymphadenopathy; in males inguinal nodes are most commonly involved and in females intrapelvic and pararectal nodes
  • Enlargement of chain of lymph nodes above and below inguinal ligament (groove sign)
  • Late sequelae - rectal strictures and elephantiasis of vulva (esthiomene)
  • Clinical, sigmoidoscopic and histologic findings resemble Crohn's disease in homosexual men
  • Frei's test: intradermal test for LGV
CHLAMYDIA PSITTACOSIS:
  • Chlamydia psittaci causes psittacosis, a febrile illness characterized by pneumonitis and systemic menifestations.
  • Human infection is acquired from inhalation of aerosols liberated from birds (parrots) dropping and nasal discharge.
  • IP : 7-14 days
  • Usual presentation is pneumonia
  • Others: Meningoencephalitis, Arthritis , Splenomegaly ,Thrombophlebitis, Pericarditis, Typhoid like syndrome, Hepatomegaly, Pulmonary infarction, Endocarditis, Horder's spot, GI symptoms
CHLAMYDIA PNEUMONIAE
  • TWAR strain (Taiwan Acute Respiratory)
  • Risk of atherosclerosis
  • The group specific antigen is responsible for the production of complement fixing antibodies in Chlamydia pneumoniae
RESISTANCE:
  1. Chlamydia has developed number of ways to evade aggressive immune responses and secure survival:
  2. Anti-apoptotic activity
  3. Chlamydial proteasome like activity molecule into host cell cytoplasm degrades host transcription factors RFX-5 & USF-1 necessary for transcription of class-I and class-II molecule Molecular mimicry:Chlamydia induced INF-y inhibits INF-y dependent expression of MHC class-II proteins.
Exam Question
  • Chlamydia escapes killing by Molecular mimicry
  • Chlamydia can cause infertilty due to Salphingiti
  • s Chlamydia causes Urethritis,LGV ,Trachoma, epididymitis, proctitis,conjunctivitis, Reiter's syndrome, acute urethral syndrome, bartholinitis, mucopurulent cervicitis, endometritis, salphingitis(infertility), pelvic inflammatory disease, conjunctivitis, perihepatitis (Fitz-Hugh-Curtis syndrome) and Reiter's syndrome
  • The syndromic management of urethral discharge includes treatment of Neisseria gonorrhoeae and Chlamydia trachomatis
  • Inclusion conjunctivitis is caused by C. Trachomatis serotypes D - K
  • Chlamydia trachomatis occurs in two forms during its life cycle(biphasic)
  • In Chlamydia trachomatis Reticulate body divides by binary fission
  • Inside the cell Chlamydia trachomatis evades phagolysome
  • The group specific antigen is responsible for the production of complement fixing antibodies in Chlamydia pneumoniae
  • Chlamydia Causes Lymphogranuloma venerum
  • Chlamydia psittaci Causes Psittacosis (parrot fever, parrot disease, or ornithosis)
  • C. trachomatis is the most common cause of nongonococcal urethritis (NGU) and post gonococcal urethritis (PGU).
  • Chlamydia Trachomatis inhibits apoptosis of epithelial cells
  • Chlamydia Trachomatis has an ability to inhibit lysosomal fusion
  • Chlamydia Trachomatis causes Scarring of the cornea leading to blindnes
  • Patient with inguinal lymphadenopathy with distinct extracellular and intracellular forms of infective organism are diagnosed to have lymphogranuloma venereum caused by chlamydia trachomatis
  • Most common organism associated with reactive arthritis is Chlamydia
  • Herbert’s pits are diagnostic of CHLAMYDIAL CONJUNCTIVITIS
  • Chlamydiae are obligate intracellullar bacterial parasite
  • Chlamydiae do not have peptidoglycan cell wall. 
  • Chlamydia produces basophilic (intracytoplasmic) inclusion bodies in infected cells
  • Chlamydia psittacosis is Acquired from bird's droppings
  • Infectious part of chlamydia is Elementary body
  • Chlamydia trachomatis infection commonly causes infertility
  • Chlamydia Pneumoniae presents the strongest association with human atherosclerosis.
  • chlamydia differ from other usual bacteria as they Contains inclusion body
  • Swimming pool conjunctivitis is caused by Chlamydia trachomatis
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