Chlamydia, Mycoplasma & Ureaplasma Flashcards
Chlamydia main points and 4 main species
> Non-Motile Gram Negative Bacteria
> Obligate intracellular Parasites
> Rely on host cell ATP for energy (Energy Parasites)
> Three species cause disease in Humans
- C. pneumoniae
- C. trachomatis
- C. psittaci (infect animals and birds also)
> All species have Lipopolysaccharide (LPS) and Major Outer Membrane Protein (MOMP) antigens that can be used in identification (serotypes)
Chlamydia Replication Cycle
> Two Forms Elementary Body (EB) - Small, round and infectious Reticulate Body (RB) - Larger and noninfectious
> EB attaches to a host cell which forms a phagosome and ingests the EB
EB forms a RB and replicates by binary fusion
RB’s reorganizes and forms EB’s
The cell ruptures and release the EB’s
Chlamydia microscopic appearance
> Cytoplasmic inclusions are present in infected host cells
May be seen with a fluorescent antibody stain, Giemsa stain
or iodine stain
Chlamydia Trachomatis serologically variant strains
Serovars A, B, Ba, and C
> Serovars L1-L3
> Serovars D-K
Serovars A, B, Ba, and C
- Cause Trachoma - a serious eye disease
- Cause of endemic in Africa and Asia that is characterized by chronic
conjunctivitis and can lead to blindness
Serovars L1-L3
- Cause Lymphogranuloma venereum (LGV) - STD
- Associated with genital ulcer disease in tropical countries
- Groin lymph nodes may become filled with pus (bubo)
Serovars D-K
> Cause genital tract infections
Men - Cause Nongonococcal Urethritis (NGU)
- Can cause epididymitis, prostatitis and proctitis
Women - Cause urethritis, cervicitis, endometritis, PID, salpingitis and
proctitis
- Lead to infertility
> Inclusion Conjunctivitis
- Occur in adults and newborns
- inflammation of the mucous membrane covering the eyeball and the eyelid
Newborn Infections (C. Trachomatis)
neonatal conjunctivitis and pneumonia
pneumonia (if present) beginning at 1-3
months
conjunctivitis (if present) developing at 1-
2 weeks
- In pneumonia - cough and fever
- In conjunctivitis - eye discharge, eye swelling or both
C. trachomatis Specimens (will depend on clinical manifestations)
Must contain host epithelial cells
> Endocervical, urethral and conjunctival swabs
- Urethral swabs should be collected at least one hour after urination
> Endocervical material (cytologic brush)
> Biopsies
> Lower Respiratory Secretions
> Aspirates from suspected LGV buboes
> Urine
C. trichomatis specimen collection
- dacron, cotton & calcium alginate swabs can be ised
- wooden handled swabs should NOT be used ( may be toxic )
C. trichomatis specimen transport
- specimens for culture must be placed in transport media & transported at 4 degrees celsius
transport media
- 2-sucrose Phosphate ( 2SP)
- sucrose Glutamate Phosphate
- should arrive to lab within 24hrs of collection & be refrigerated
- frozen(-70) if processing delayed
C.trichomatis ID ( culture methods )
> Direct Examination - Sensitive but technically demanding and
dependent on the quality of the specimen
> Direct Fluorescent Antibody (DFA) Test
- Most sensitive method
- Requires an experienced microscopist and is labor intensive
- Should not be used routinely for genital tract specimens
> Iodine Stains
- Stains the glycogen in C. trachomatis inclusions
C. trichomatis ID ( non culture methods)
transport less rigorous than culture methods because
tests do not require viable organism
> DFA Tests
- Used on endocervical, urethral, conjunctival and respiratory
specimens
> Enzyme Immunoassay (EIA)
> Nucleic Acid Detection Tests - Detects the bacterial RNA -
Preferred Method
> Giemsa Stained Smears
C.trichomatis CDC ID recommendation
> Non-culture methods give a presumptive diagnosis
Results may be confirmed with a culture method test or a second
non- culture method test
> CDC Recommends that Culture Tests be performed on the following:
- Urethral specimens from women and asymptomatic men
- Nasopharyngeal specimens from infants
- All rectal specimens
- Vaginal specimens from prepubertal girls
- Medicolegal cases (ex. Sexual abuse)
C. pneumoniae
- common respiratory pathogen, may cause flulike symptoms, pneumonia, bronchitis, pharyngitis and sinusitis
> Also associated with asthma, coronary heart disease and
Guillain Barre syndrome ( rare autoimmune disorder)
> Detected with Fluorescein-labeled anti-C. pneumoniae
antibodies
> May be diagnosed serologically
C.psittaci
> Causes ornithosis (zoonotic disease)- Parrot Fever
> Usually acquired from infected birds - Inhalation of the
bacteria
> Patients may be asymptomatic or have a fever and
pneumonia
> Detected through serology
Mycoplasma & Ureaplasma
- Widely distributed in nature and are found in humans, animals
and the environment
The smallest, self replicating organisms (once thought to be
viruses)
Bacteria lacking a cell wall (Not stained with Gram stain)
Range in size from coccoid to tapered rods (Pleomorphic)
Significant Human Pathogens:
> Mycoplasma pneumoniae (Respiratory tract disease)
> Mycoplasma hominis (Urogenital tract disease)
> Ureaplasma urealyticum (Urogenital tract disease)
Mycoplasma
Mycoplasma spp. are generally slow growers, highly fastidious
and facultative anaerobes
small colonies ranging in size from 15um-300um
Often grow embedded beneath the surface of solid media
Some species form colonies with raised centers (“fried egg
appearance”)
Common contaminants
Mycoplasma pneumoniae ( what it causes, how it is transmitted,)
- infects respiratory tracts, causes primarily atypical pneumonia- “ walking pneumonia”
> NOT a normal commensal organism
> Isolation in significant and considered a pathogen
> Can also cause pharyngitis and bronchitis
> Rarely spreads to other body sites
> Transmission most likely through aerosol droplet spray
M.pneumoniae ( common age and season infected, symptoms)
> occurs in older children, teenagers and young adults
> occur in fall/early winter
around back- to-school time
> connected to closed-in populations ex.
Military bases, prisons, dormitories
> Infections could be asymptomatic or very mild
> Symptoms can include headache, low-grade fever, malaise,
anorexia, dry cough
Mycoplasma hominis
> Colonize the urogenital tracts of many sexually active adults
> Opportunistic pathogen
> Associated with Bacterial Vaginosis (BV), PID, postpartum
fever, meningitis in premature infants and other infections
> Not reported as a cause of Nongonococcal Urethritis (NGU)
Ureaplasma urealyticum
> Colonize the urogenital tracts of many men and women
> May cause NGU in men
> Does not cause disease in the lower genital tract of females
> Associated with BV and upper genital tract infections in
females
Mycoplasma & Ureaplasma in newborns & immunocompromised
M. hominis and Ureaplasma spp. can be transmitted to
neonates during delivery
Associated with congenital bacteremia, pneumonia and chronic
lung disease in premature infants
U. urealyticum is a common organism isolated from tracheal
aspirates of low birth weight infants with respiratory disease
- sometimes isolated from infants born via caesarean section
(infection occurring in utero)
\ recovered from CSF specimens in high risk
newborns (premature, low birth weights)
* If CSF is negative for bacteria, when symptoms suggest
meningitis, culture for M. hominis and U. urealyticum should be
performed
In immunocompromised individuals, can lead to bacteremia and
invasive disease of joints and respiratory tract
Mycoplasma & Ureaplasma specimen collection & transport
> Specimens may include body fluids, blood, sputum, synovial fluid, CSF,
amniotic fluid, urine, wound aspirates, tissue samples, nasopharyngeal swabs,
cervical swabs and vaginal swabs
> The lack of cell wall make these organisms are sensitive to drying and heat
> If transport delayed, specimens should be placed in a transport medium
such as SP4, Shepard 10B broth or 2SP
> Cotton tip swabs and wooden shafts should be avoided - inhibitory effects
Swabs should be made of Dacron polyester or calcium alginate with aluminum
or plastic shafts
> On arrival in the laboratory, specimens should be placed in fridge and
processed within 6 hrs or frozen at - 70 degree Celsius if delayed more than 24hrs
Mycoplasma & Ureaplasma direct examination
> Gram stain not useful due to lack of cell wall
DNA fluorescent stain maybe use but not specific (ex. acridine orange)
PCR technology may be used for detection
Mycoplasma & Ureaplasma Culture
> Often done at the reference laboratory
> Special media have been developed for isolation
> Media is enriched with sterols and other nutrients (dependant on
species)
> Antimicrobial agents often included to inhibit contaminants
> M. hominis and U. urealyticum may grow on NYC media
M. hominis may be cultured on BAP and CHOC agar
I Mycoplasma & Ureaplasma incubation period
> M. pneumoniae are incubated for 3-4 weeks
M. hominis and U. urealyticum held for one week before
reported as negative
Mycoplasma & Ureaplasma Identification
> Mycoplasma colonies often have the fried egg appearance
> Ureaplasmal colonies are very small and do not tend to have
the fried egg appearance - hard to see with the naked eye
> Key characteristic used to identify U. urealyticum is its ability to hydrolyze urea
> Serology testing used to detect antibodies but typically done at the reference
lab level
Mycoplasma & Ureaplasma Antimicrobial susceptibility
> Resistant to many antimicrobials due to the lack of a cell wall
> M. pneumoniae is susceptible to tetracyclines, newer fluoroquinolones and
macrolides (erythromycin) but resistance is emerging
> Standard antimicrobial sensitivity testing should be conducted
