MISCELLANEOUS BACTERIA
Credits to: Jaeckel F. Gosiengfiao
Edwin L. Sagun, Jr.
• Chlamydia
– Obligate intracellular
– Infectious particle : elementary body
• C. psittaci (Chlamydophila psittaci)
– Agent of psittacosis/ornithosis, a disease of birds,
parrots, parakeets, and cockatoos
– Human may acquire the infection by inhalation of
contaminated aerosols or fomites or through
person to person transmission
• C. pneumoniae (Chlamydophila pneumoniae)
– Associated with mild respiratory tract infections
– TWAR strain
C. trachomatis
SUBTYPES CLINICAL SYNDROME
A, B, Ba, C Endemic trachoma (multiple or persistent
infections that ultimately lead to blindness)
D-K Urethritis, cervicitis, pelvic inflammatory disease,
epididymitis, infant pneumonia and conjunctivitis
L1, L2, L3 Lymphogranuloma venereum
Use of Different
Laboratory Tests
to Diagnose
C. trachomatis
Infections
• Mycoplasma
– Smallest free living organism, found in several
animals and plants
– Lack cell wall; pleomorphic in appearance
– Originally known as pleuropneumonia-like
organism (PPLOs), since they were first discovered
causing pleuropneumonia in cattles
• Mycoplasma pneumonia
– Eaton’s agent; frequent cause of community
acquired pneumonia and tracheobronchitis in
children and young adults
– Primary atypical pneumonia/walking pneumonia
• Genital Mycoplasmas: M. hominis and U.
urealyticum
– Can colonize adults asymptomatically and are also
cause of nongonococcal urethritis in males
– M. hominis has also been identified as an agent of
salpingitis and postpartal fever in females
Basic Biochemical Differentiation of the Major
Mycoplasma spp. and Ureaplasma urealyticum
Colonial growth characteristics of
Mycoplasma in agar medium.
Rickettsia
• Include the genera: Rickettsia, Ehrlichia, Coxiella, and
Rochalimea
• Gram-neg, obligately intracellular bacteria
• Infections are spread through insect vectors such as lice,
fleas, and ticks
• All rickettsia, except Coxiella, cannot survive outside the
animal host or insect vector
• Signs of infection include fever, headache, characteristic
rash that first appears on the wrists and ankles
• Other manifestation of infection, include conjunctivitis,
pharyngitis, and mild respiratory distress
• All requires tissue culture media except R. Quintana
Characteristics of Rickettsial Infections
• rickettsiae are short rods, or coccobacilli, that are
obligate, intracellular, gram-negative bacteria
• two distinct groups: the spotted fever group (SFG)
and the typhus group (TG)
• associated with arthropods: ticks, mites, lice, or
fleas
• R. japonica is found only in Japan, while R.
rickettsii is found in the Western Hemisphere
• R. typhi, are found everywhere in the world
GROUP SPECIES INFECTION TRANSMISSION
Spotted Fever Rickettsia rickettsii Rocky Mountain Spotted Ticks
Fever
R. akari Rickettsialpox Mites
R. australis Australian/Queensland tick ticks
typhus
R. conorii Boutonneuse fever Ticks
Mediterranean and Israeli
spotted fevers; Indian tick
typhus, Kenya tick typhus
Typhus R. prowazekii Epidemic typhus Lice
Sporadic typhus Flying squirrels
Brill-Zinsser disease Reactivation of latent infection
R. typhi Murine typhus/Endemic Fleas
typhus
Scrub typhus R. tsutsugamushi Scrub typhus Mites, chiggers
Q fever Coxiella burnetti Q fever Ticks, aerosol
Ehrlichiosis E. chaffeensis Human monocyte ehrlichiosis Ticks
E. phagocytophila Human granulocyte Ticks
E. ewingii ehrlichiosis
Neorickettsia sennetsu Sennetsu fever Ticks
(former E. sennetsu)
Rochalimeae Rochalimea quintana Trench fever Lice
Characteristics of Rickettsial Infections
• Rocky Mountain spotted fever
– symptoms occur approximately 7 days after a tick bite
– fever, severe headache, malaise, and myalgia, accompanied by nausea,
vomiting, abdominal pain, and sometimes a cough
– rash, which starts on the hands and feet and proceeds to the trunk,
appears in 3 to 5 days after the beginning of other symptoms
– increase in vascular permeability and focal hemorrhages.
• Murine typhus
– Symptoms: cough and chest infiltrate suggestive of pneumonia
– severe manifestations: seizures, coma, and respiratory failure
Serological Diagnosis
• probe-based immunoassays and agglutination
assays
• antibodies produced in patients with
rickettsial infections were detected by an
agglutination test known as the Weil-Felix test
– which was based on cross-reactivity of the
patient’s antibodies with polysaccharide antigens
present on the OX-19 and OX-2 (Proteus vulgaris)
and the OX-K (Proteus mirabilis)
• Patients with R. prowazekii (epidemic typhus), R.
typhi (murine typhus), and R. rickettsii (Rocky
Mountain spotted fever) will be positive for OX-19
• Patients with O. tsutsugamushi (scrub typhus) will be
positive for OX-K
• Patients with Rickettsia spp. of the spotted fever
group, but not R. rickettsii, will be positive for OX-2
• Titers of >1 : 320 or a fourfold rise in titer between
an acute and convalescent sample are considered
positive results
Serological Assays
• indirect fluorescent assays (IFA),
microimmunofluorescent assays (micro-IF),
immunoperoxidase assays (IPA), ELISA, and
immunoblot assays (IBA)
• IFA and IPA require the whole bacterium as the
reagent
• ELISA and IBA use rickettsial antigens adsorbed
onto a solid phase or nitrocellulose membrane
• IFA test and the micro-IF- gold standard for
detecting rickettsial antibodies
Molecular Techniques
• PCR using primers that target genes of the TG
and SFG groups of organisms
– citrate synthase gene and the 17 kDa antigen
gene both for SFG and TG
– 190 kDa antigen (Omp A) gene and the 120 kDa
antigen (OmpB) gene are used only to detect the
SFG group
• real-time PCR for rickettsial species
identification
END OF MICROBIOLOGY I
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RD
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