Microbiology and Pathogenic Organisms Overview

What are the characteristics of Treponema?

Thin, spiral organisms with 3 axial filaments; difficult to stain; best demonstrated in darkfield microscopy; microaerophilic; killed rapidly at 42 °C; remains viable in whole blood or plasma for at least 24 hours; can cross the placenta and intact mucous membranes.

What is the causative agent of syphilis?

Treponema pallidum subsp. pallidum.

What is the generation time of Treponema pallidum?

30 hours.

What are the transmission methods for syphilis?

Sexual contact, vertical transmission, skin contact with active lesions, transfusion of fresh blood, and injuries from contaminated needle sticks.

What are the symptoms of primary syphilis?

Chancre, fever, sore throat, headache, rashes, and gummas of the skin.

What are the stages of syphilis?

Primary, Secondary, Latent, and Tertiary.

What occurs during the primary stage of syphilis?

Painless sores form on genitals, rectum, or mouth, developing 10 to 90 days after infection.

What are the characteristics of secondary syphilis?

Develops 2 to 10 weeks after primary syphilis; systemic involvement with fever, sore throat, headache, generalized lymphadenopathy, skin rashes, and mucosal lesions.

What is the latent stage of syphilis?

A subclinical period that occurs more than a year after infection; diagnosis can only be made by serologic tests.

What is the treatment for primary, secondary, and early latent syphilis?

Typically treated with a single dose of intramuscular benzathine penicillin G.

What is the treatment for late latent and tertiary syphilis?

May require multiple doses of penicillin, often given weekly for three weeks.

What is required for the treatment of neurosyphilis, ocular syphilis, and otosyphilis?

A longer course of intravenous antibiotics, often lasting 10-14 days.

What are the pathogenic spirochetes?

Treponema (T. pallidum subsp. pallidum and T. pallidum subsp. pertenue), Borrelia (B. recurrentis and B. burgdorferi), and Leptospira interrogans.

What are the characteristics of pathogenic spirals?

Gram negative, motile, slender, rigid organisms with amphitrichous flagella.

What is the appearance of the chancre in primary syphilis?

It is an infectious primary lesion that is painless and usually seen on the genitalia.

What are the systemic manifestations of secondary syphilis?

Fever, sore throat, headache, generalized lymphadenopathy, skin rashes involving the palms and soles, and mucosal lesions.

What is the significance of axial filaments in Treponema?

They are responsible for the motility of the organism.

What is the clinical significance of Treponema pallidum subsp. pertenue?

It is associated with yaws, a chronic skin disease.

What is the role of darkfield microscopy in studying Treponema?

It is the best method to demonstrate these thin, spiral organisms.

What is the characteristic of Treponema in terms of oxygen requirement?

It is microaerophilic.

What is the effect of temperature on Treponema?

It is killed rapidly at 42 °C.

What is the duration Treponema remains viable in whole blood or plasma?

At least 24 hours.

What are the two subspecies of Treponema pallidum mentioned?

T. pallidum subsp. pallidum and T. pallidum subsp. pertenue.

What is the causative agent of yaws?

The causative agent of yaws is Treponema pallidum, the same bacterium that causes syphilis.

How is yaws acquired?

Yaws is acquired through direct contact with a skin lesion.

What characterizes the tissue-destructive phase of yaws?

It is the phase where significant tissue damage occurs, potentially developing 3 to 10 years after secondary syphilis.

What are some complications associated with yaws?

Complications include neurosyphilis, cardiovascular abnormalities, eye disease, and granulomatous-like lesions (gummas).

How is congenital syphilis transmitted?

Congenital syphilis is transmitted through the placenta.

What are the possible outcomes for a fetus exposed to syphilis in utero?

Possible outcomes include abortion, stillbirth, being born alive with syphilis, or being born healthy but showing evidence of syphilis later.

What is the recommended method for laboratory diagnosis of yaws?

Direct microscopic examination of exudates is recommended.

What is the definitive test for diagnosing yaws?

The definitive test is dark field microscopy for the observation of motility.

What stains are used in the laboratory diagnosis of yaws?

Levaditi's stain and Fontana-Tribondeau stain are used.

What is the role of fluorescein isothiocyanate-labeled antibody (FITC) in diagnosis?

FITC is used for the direct detection of Treponema pallidum in lesions.

What type of antibodies do nontreponemal tests detect in serodiagnosis?

Nontreponemal tests detect non-specific antibodies against lipoidal antigens released when Treponema pallidum infects the host.

What are the serodiagnostic tests used to monitor syphilis treatment?

Rapid plasma regain (RPR), Venereal disease research laboratory (VDRL), Unheated serum regain (USR), Toluidine red unheated serum test (TRUST), and ELISA.

What type of test detects antibodies to treponemal antigens?

Treponemal test.

What is the characteristic lesion of primary yaws?

A wart-like thickening of the epidermis that becomes fibrous, cracks open, bleeds easily, and discharges serous fluid.

How long after infection does primary yaws typically develop?

9-90 days, with an average of 21 days.

What are the symptoms of secondary yaws?

Multiple raised yellow skin lesions, bone pain, and swelling of the joints.

What is the duration of the secondary yaws stage?

It can last for months, with periods of active lesions followed by healing.

What characterizes tertiary yaws?

Destructive lesions affecting the skin, bones, and cartilage, occurring 5 to 10 years after the initial infection.

What is the preferred treatment for yaws according to WHO?

Azithromycin (single oral dose) at 30 mg/kg (maximum 2 gm).

What is an alternative treatment for yaws for patients allergic to penicillin and azithromycin?

Doxycycline 100mg orally, twice daily for 7 days.

What is the causative agent of Lyme disease?

Borrelia species.

What is the vector for Lyme disease?

Hard tick (Ixodes).

What is the hallmark symptom of Lyme disease?

Erythema migrans (bull's eye lesion on the skin).

What are the stages of Lyme disease?

First stage (erythema migrans), second stage (dissemination with neurologic symptoms), third stage (chronic symptoms).

What is the diagnostic feature of Lyme disease?

Presence of erythema migrans or a red, ringed-shaped lesion at the site of the tick bite.

What microscopy techniques are used for laboratory diagnosis of Borrelia?

Dark-field microscopy and Giemsa or Wright stain.

What is the specimen of choice for diagnosing relapsing fever?

Peripheral blood.

What is the causative agent of epidemic-relapsing fever?

Borrelia recurrentis.

What is the vector for epidemic-relapsing fever?

Pediculus humanus corporis (body louse).

What happens when a louse feeds on a febrile patient with relapsing fever?

The louse becomes infected.

What are the laboratory diagnosis methods for Lyme disease?

Blood, CSF, and biopsy specimens; Warthin-Starry stain for tissue sections; Giemsa stain for blood and CSF.

What are the characteristics of Borrelia species?

Gram-negative, corkscrew-shaped spirochetes.

What are the potential long-term effects of Borrelia recurrentis infection?

Recurring chronic arthritis and possible demyelination of neurons.

What tests are used to monitor the treatment of syphilis?

Serodiagnostic tests include Rapid Plasma Reagin (RPR), Venereal Disease Research Laboratory (VDRL), Unheated Serum Reagin (USR), Toluidine Red Unheated Serum Test (TRUST), and ELISA.

What is a treponemal test?

It detects the presence of antibodies to treponemal antigens.

What are the two types of treponemal/specific tests?

Indirect fluorescent antibody test (FTA-ABS) and others.

What characterizes primary yaws?

A wart-like thickening of the epidermis that cracks open, bleeds easily, and discharges serous fluid, typically developing 9-90 days after infection.

What defines tertiary yaws?

Destructive lesions affecting the skin, bones, and cartilage occurring 5 to 10 years after the initial infection.

What is the preferred treatment for yaws?

Azithromycin (single oral dose) at 30 mg/kg (maximum 2 gm) or Benzathine penicillin (single intramuscular dose) at 1.2 million units for adults.

What is the alternative treatment for patients allergic to penicillin and azithromycin?

Doxycycline 100 mg orally, twice daily for 7 days.

What are the hallmark signs of Lyme disease?

Erythema migrans (bull's eye lesion) and swelling.

What occurs in the first stage of Lyme disease?

Presence of erythema migrans at the site of the tick bite.

What characterizes the second stage of Lyme disease?

Dissemination of the organism to other parts of the body, with neurologic disorders and nerve palsy.

What is the third stage of Lyme disease characterized by?

Chronic arthritis and possible demyelination of neurons.

What laboratory techniques are used for diagnosing Lyme disease?

Microscopic examination, Giemsa stain, and dark-field microscopy.

How does a louse become infected with Borrelia recurrentis?

By feeding on a febrile patient with relapsing fever.

What staining techniques are used for Leptospira species?

Giemsa or Wright stain.

What is the specimen of choice for Lyme disease diagnosis?

Blood, CSF, and biopsy specimens.

What is the significance of the Warthin-Starry stain?

It is used for tissue sections in the diagnosis of Lyme disease.

What is the role of dark-field microscopy in diagnosing spirochete infections?

It is used for the detection of organisms in blood cultures after 2-3 weeks of incubation.

How is Borrelia recurrentis transmitted to humans?

Transmission occurs when the louse is crushed, allowing Borrelia recurrentis from its hemocoel to enter the human body through intact skin or mucous membranes.

What are the common symptoms of relapsing fever caused by Borrelia recurrentis?

Symptoms include high fever, headache, muscle and joint pain, nausea, and vomiting.

What culture media is used for culturing Borrelia recurrentis?

Barbour-Stoenner-Kelly medium or chick embryo.

Which antibiotics are typically effective in treating relapsing fever?

Antibiotics such as tetracyclines, doxycycline, erythromycin, or procaine penicillin G.

What is the significance of PCR in relation to Borrelia burgdorferi?

PCR is important for the diagnosis of B. burgdorferi DNA in urine.

What is the characteristic of the illness caused by Leptospira?

This form of the illness is rarely fatal and represents approximately 90% of all documented cases of Leptospirosis.

What microscopy technique is used for the laboratory diagnosis of Leptospira?

Dark field microscopy.

What specimens are preferred for culturing Leptospira?

Blood, CSF, and urine specimens.

What is the medium of choice for culturing Leptospira?

Fletcher's medium, BMUH medium, Bovine serum albumin, or Stuart's broth.

What are the characteristics of Leptospira interrogans?

Obligate aerobes, tightly coiled, highly motile with hooked ends, live in the renal tubules, and shed in urine.

Which animals are recommended for the cultivation of Leptospira?

Hamsters and guinea pigs.

What is the generation time for Leptospira?

6 to 16 hours.

What antibiotics can be used to treat Leptospira infections?

Doxycycline, amoxicillin, or ampicillin; severe infections may require intravenous penicillin G, third-generation cephalosporins, or erythromycin.

What are the characteristics of Campylobacter jejuni?

Gram-negative bacterium, curved, slender, motile rod, and microaerophilic.

How is Campylobacter jejuni commonly transmitted to humans?

It is often transmitted from animals to humans, with poultry being a major source of infection.

What is a common illness caused by Campylobacter bacteria?

Campylobacter bacteria are a common cause of diarrheal illness.

What illness is caused by Campylobacter infection?

Campylobacteriosis.

How do people most commonly acquire Campylobacter infection?

By eating raw or undercooked poultry.

What are other ways to contract Campylobacter infection?

Eating contaminated foods, drinking untreated water, and touching infected animals.

What is the primary antibiotic choice for Campylobacter jejuni gastroenteritis?

Azithromycin, typically 500 mg for 3 days.

What is the classic antibiotic of choice for Campylobacter infection?

Erythromycin.

What is the causative agent of leptospirosis?

Spirillum minus.

How can leptospirosis be contracted?

Through water or soil contaminated by animal urine entering the body via the nose, mouth, eyes, or breaks in the skin.

What are common symptoms of leptospirosis?

Fever, headache, myalgia, anorexia, and vomiting.

What are the modes of acquisition for leptospirosis?

Entry through breaks in skin, direct contact with urine or carriers, and contact with contaminated water.

What is Icteric or Weil syndrome?

A severe form of leptospirosis affecting the liver and kidneys, causing jaundice, kidney failure, liver failure, internal hemorrhaging, and respiratory distress.

What percentage of cases may result in death from Icteric or Weil syndrome?

Up to 10%.