157: Tuberculosis and Infections with Atypical Mycobacteria Flashcards
1
Q
What is the global impact of tuberculosis (TB) in terms of its ranking as a cause of death?
A
Tuberculosis (TB) is currently the ninth leading cause of death worldwide and the leading cause from an infectious agent, ranking higher than HIV/AIDS.
2
Q
How does HIV status affect the likelihood of developing tuberculosis (TB)?
A
HIV-positive individuals are approximately 20 times more likely than HIV-negative individuals to develop TB in countries with a generalized HIV epidemic, and between 26 and 37 times more likely in countries where HIV prevalence is lower.
3
Q
What are the two most frequent forms of skin tuberculosis?
A
The two most frequent forms of skin tuberculosis are lupus vulgaris (LV) and scrofuloderma.
4
Q
What is the relationship between the AIDS epidemic and tuberculosis (TB)?
A
The AIDS epidemic has led to a resurgence of tuberculosis and the appearance or recognition of new mycobacterial pathogens, with the incidence of TB in AIDS patients being almost 500 times that in the general population.
5
Q
What is the most common cause of disseminated bacterial infections in patients with AIDS in the United States?
A
The Mycobacterium avium-intracellulare complex is the most common cause of disseminated bacterial infections in patients with AIDS in the United States.
6
Q
What are the routes of infection for cutaneous tuberculosis?
A
Routes of infection for cutaneous tuberculosis include:
- Cutaneous inoculation leading to a tuberculous chancre or tuberculosis verrucosa cutis.
- Spread of mycobacteria by continuous extension of a tuberculous process in the skin (scrofuloderma) via the lymphatics.
- Hematogenous dissemination, which can lead to acute miliary tuberculosis of the skin or lupus vulgaris (LV).
7
Q
Which countries had the highest burden of TB disease in 2016?
A
India, Indonesia, China, the Philippines, and Pakistan.
8
Q
What is the significance of atypical mycobacteria (MOTT) in relation to skin disease?
A
MOTT causes skin disease more frequently than Mycobacterium tuberculosis.
9
Q
How do mycobacteria multiply in the body?
A
Mycobacteria multiply intracellularly and are initially found in large numbers in the tissue.
10
Q
What is the significance of tuberculin sensitivity in individuals infected with M. tuberculosis?
A
Tuberculin sensitivity usually develops 2 to 10 weeks after infection and persists throughout life. In patients with clinical tuberculosis, an increase in skin sensitivity usually indicates a favorable prognosis.
11
Q
What are the key components of the Quantiferon-TB Gold test?
A
The Quantiferon-TB Gold test involves mixing blood samples with antigens representing M. tuberculosis proteins (ESAT-6 and CFP-10). After incubation for 16 to 24 hours, the amount of interferon (IFN-γ) released in response to the antigens is measured.
12
Q
What is the hallmark histopathological feature of tuberculosis?
A
The hallmark of tuberculosis is the tubercle, which is an accumulation of epithelioid histiocytes with Langhans-type giant cells and varying amounts of caseation necrosis in the center, surrounded by a rim of lymphocytes and monocytes.
13
Q
What is the sensitivity and specificity of PCR testing in multibacillary and paucibacillary disease?
A
In multibacillary disease, PCR testing showed 100% sensitivity and specificity. In contrast, in paucibacillary disease, PCR testing showed 55% sensitivity and specificity.
14
Q
What is the general treatment approach for cutaneous tuberculosis?
A
The management of cutaneous tuberculosis is similar to that of tuberculosis of other organs, with chemotherapy being the treatment of choice.
15
Q
What special considerations are there in treating tuberculosis of the skin?
A
In treating localized forms of tuberculosis verrucosa cutis without evidence of associated internal tuberculosis, isoniazid alone may be used for up to 12 months.
16
Q
What is the tuberculin reaction and its significance in diagnosing tuberculosis?
A
The tuberculin reaction is a delayed-type hypersensitivity reaction induced by mycobacteria during primary infection, used as a diagnostic test for tuberculosis.
17
Q
What does the Quantiferon-TB Gold test measure?
A
It measures the amount of interferon released by white blood cells in response to specific TB antigens, indicating infection with M. tuberculosis.
18
Q
What is the hallmark of tuberculosis in histopathology?
A
The tubercle, which is an accumulation of epithelioid histocytes with Langhans-type giant cells and caseation necrosis.
19
Q
What is the role of PCR testing in diagnosing cutaneous tuberculosis, and what are its limitations?
A
PCR testing is used to ascertain the presence of mycobacterial DNA in skin specimens. In multibacillary disease, PCR testing shows 100% sensitivity and specificity, while in paucibacillary disease, it shows 55% sensitivity and specificity.
20
Q
What treatment options are available for cutaneous tuberculosis, and what additional measures may be required?
A
The treatment of cutaneous tuberculosis generally involves chemotherapy, similar to that for other forms of tuberculosis. Ancillary measures may also be required.
21
Q
What special considerations should be taken into account when treating localized forms of tuberculosis verrucosa cutis?
A
Localized forms of tuberculosis verrucosa cutis may be treated with isoniazid alone for up to 12 months.
22
Q
What is the role of surgical intervention in treating scrofuloderma?
A
Surgical intervention is quite helpful in scrofuloderma as it reduces morbidity and shortens the required length of chemotherapy.
23
Q
What defines extensively multidrug-resistant TB?
A
Extensively multidrug-resistant TB is defined as resistance to at least rifampicin and isoniazid, in addition to resistance to any fluoroquinolone and to at least one of the three injectable second-line anti-TB drugs.
24
Q
What are the clinical findings associated with primary inoculation tuberculosis?
A
The clinical findings include:
- A small papule, crust, or erosion at the site of inoculation appearing 2 to 4 weeks after infection.
- A painless ulcer that may enlarge to more than 5 cm.
25
What diagnostic methods are used for primary inoculation tuberculosis?
Diagnosis is confirmed by identifying any ulcer with little or no tendency to heal and unilateral regional lymphadenopathy in a child.
26
What is the typical course of untreated primary inoculation tuberculosis?
If untreated, the condition may last up to 12 months. The regional lymph nodes usually calcify, and the primary tuberculous complex may produce immunity.
27
A child presents with unilateral cervical lymphadenopathy and a painless ulcer. Acid-fast organisms are found in the ulcer. What is the diagnosis and the diagnostic test that confirms it?
The diagnosis is primary inoculation tuberculosis. The diagnostic test that confirms it is bacterial culture.
28
What is the primary inoculation tuberculosis?
It is characterized by tuberculous chancre and affected regional lymph nodes in the skin.
29
Who is most often affected by primary inoculation tuberculosis?
Children are most often affected.
30
What are the initial clinical findings of a tuberculous chancre?
It appears as a small papule, crust, or erosion with little tendency to heal, usually 2 to 4 weeks after inoculation.
31
What is a common characteristic of ulcers caused by inoculation tuberculosis?
They may be shallow with a granular or hemorrhagic base and can be studded with miliary abscesses or covered by necrotic tissue.
32
What should raise suspicion in a child regarding ulcers and lymphadenopathy?
Any ulcer with little or no tendency to heal and unilateral regional lymphadenopathy.
33
What is the significance of the PPD reaction in diagnosing tuberculosis?
The PPD reaction is negative initially and later converts to positive, indicating an immune response to TB.
34
What may happen if primary inoculation tuberculosis is untreated?
The condition may last up to 12 months and can lead to reactivation of the disease or hematogenous spread to other organs.
35
What percentage of cases may experience erythema nodosum?
Approximately 10% of cases.
36
What is the significance of surgical intervention in the treatment of scrofuloderma?
Surgical intervention is significant in treating scrofuloderma as it reduces morbidity and shortens the required length of chemotherapy. This approach is particularly beneficial for small lesions of lupus vulgaris (LV) or tuberculosis verrucosa cutis.
37
What are the clinical findings associated with primary inoculation tuberculosis?
Clinical findings include:
1. Initial appearance of a chancre 2 to 4 weeks after inoculation.
2. Development of a painless ulcer that may enlarge beyond 5 cm.
3. Regional lymphadenopathy develops 3 to 8 weeks post-infection.
4. Cold abscesses may form after weeks or months.
5. The disease may take a more acute course.
38
What diagnostic criteria should raise suspicion for primary inoculation tuberculosis in a child?
Criteria include:
- Presence of any ulcer with little or no tendency to heal.
- Unilateral regional lymphadenopathy.
- Detection of acid-fast organisms in the primary ulcer and draining nodes.
- Confirmation through bacterial culture.
- Initial PPD reaction is negative but later converts to positive.
39
What are the potential complications if primary inoculation tuberculosis is left untreated?
Potential complications include:
1. The condition may last up to 12 months.
2. Rare development of lupus vulgaris at the site of a healed tuberculous chancre.
3. Calcification of regional lymph nodes.
4. Possible reactivation of the disease.
5. Hematogenous spread may lead to tuberculosis of other organs.
6. Occurrence of erythema nodosum in approximately 10% of cases.
40
What is the primary cause of Tuberculosis Verrucosa Cutis?
It is caused by exogenous reinfection in previously sensitized individuals.
41
What are the common clinical findings associated with Lupus Vulgaris?
Common findings include solitary lesions that may involve multiple sites, typically starting on the nose, cheek, earlobe, or scalp, presenting as brownish-red, soft or friable macules or papules.
42
How does the histopathology of Tuberculosis Verrucosa Cutis differ from Lupus Vulgaris?
Tuberculosis Verrucosa Cutis shows pseudoepitheliomatous hyperplasia with marked hyperkeratosis, while Lupus Vulgaris is characterized by the formation of typical tubercles.
43
What is the typical progression of lesions in Tuberculosis Verrucosa Cutis?
Lesions progress slowly, becoming hyperkeratotic and often mistaken for common warts.
44
What demographic is most affected by Lupus Vulgaris?
Lupus Vulgaris affects females 2 to 3 times more often than males.
45
What is the diagnosis for a healthcare worker developing a hyperkeratotic lesion after handling infectious material?
The diagnosis is tuberculosis verrucosa cutis.
46
What is the diagnosis for a patient with a brownish-red plaque on the cheek that exhibits an apple jelly color on diascopy?
The diagnosis is lupus vulgaris.
47
What is the diagnosis for a patient with a chronic, progressive lesion on the nose that has a gyrate outline border?
The diagnosis is lupus vulgaris.
48
What is the diagnosis for a patient with a chronic, verrucous plaque on the hand with an irregular border?
The diagnosis is tuberculosis verrucosa cutis.
49
What is the diagnosis and histopathology for a chronic, verrucous plaque on the hand?
The diagnosis is tuberculosis verrucosa cutis. Histopathology shows pseudoepitheliomatous hyperplasia with marked hyperkeratosis.
50
What is the diagnosis and histopathology for a chronic, progressive lesion on the cheek that exhibits an apple jelly color on diascopy?
The diagnosis is lupus vulgaris. Histopathology shows typical tubercles with secondary changes.
51
What is the diagnosis for a chronic, verrucous plaque on the hand and its etiology?
The diagnosis is tuberculosis verrucosa cutis, caused by exogenous reinfection.
52
What is the diagnosis for a chronic, verrucous plaque on the hand and its complications?
The diagnosis is tuberculosis verrucosa cutis. Complications include atrophic scarring and spontaneous involution.
53
What is the diagnosis for a chronic, verrucous plaque on the hand and its treatment?
The diagnosis is tuberculosis verrucosa cutis. Treatment involves surgical excision and antituberculosis therapy.
54
What are the common clinical findings in Tuberculosis Verrucosa Cutis?
Lesions usually occur on the hands or lower extremities, often mistaken for common warts.
55
What is Lupus Vulgaris and how does it differ from Tuberculosis Verrucosa Cutis?
Lupus Vulgaris is a chronic form of cutaneous tuberculosis arising from hematogenous spread, while Tuberculosis Verrucosa Cutis is primarily due to exogenous reinfection.
56
What are the common sites of involvement for Lupus Vulgaris lesions?
Lesions usually start on the nose, cheek, earlobe, or scalp.
57
What is a characteristic feature of Lupus Vulgaris lesions on diascopy?
The infiltrate exhibits a typical apple jelly color.
58
What is the typical histopathological feature of Lupus Vulgaris?
The formation of typical tubercles is the most prominent histopathologic feature.
59
What can happen to the tuberculin reaction during Lupus Vulgaris infection?
A previously positive tuberculin reaction may become negative but usually reverts to positive.
60
What are the clinical findings associated with Tuberculosis Verrucosa Cutis?
Lesions usually occur on the hands or lower extremities, small asymptomatic papules with a purple inflammatory halo, slow growth leading to verrucous plaques, and regional lymph nodes are rarely affected.
61
How does Lupus Vulgaris differ in clinical presentation from Tuberculosis Verrucosa Cutis?
Lupus Vulgaris lesions are usually solitary, often involve the head and neck, and show a characteristic apple jelly color on diascopy.
62
What is the histopathological feature of Lupus Vulgaris compared to Tuberculosis Verrucosa Cutis?
Lupus Vulgaris shows typical tubercles, while Tuberculosis Verrucosa Cutis shows pseudoepitheliomatous hyperplasia and a dense inflammatory infiltrate.
63
What are the typical characteristics of LV plaques in the diagnosis of scrofuloderma?
Typical LV plaques are soft, brownish-red, and evolve slowly.
64
What are the common clinical findings associated with scrofuloderma?
Common findings include firm, subcutaneous nodules that soften and may lead to ulcers.
65
What complications can arise from scrofuloderma?
Complications may include involvement of nasal or auricular cartilage, atrophic scarring, and dry rhinitis.
66
What is the significance of tuberculin sensitivity in scrofuloderma?
It indicates an immune response to tuberculosis infection and aids in diagnosis.
67
What is the course of scrofuloderma without therapy?
It is a long-term disorder that progresses over many years, leading to functional impairment and potential carcinoma.
68
What is the diagnosis for a firm, subcutaneous nodule in the supraclavicular region that later softens?
The diagnosis is scrofuloderma.
69
What is the diagnosis for a painless, subcutaneous nodule in the supraclavicular region that later softens?
The diagnosis is scrofuloderma.
70
What is the diagnosis for a chronic, progressive lesion on the nose with a gyrate outline border?
The diagnosis is lupus vulgaris.
71
What is the diagnosis for a chronic, progressive lesion on the cheek that exhibits an apple jelly color?
The diagnosis is lupus vulgaris.
72
What is the treatment for a painless, subcutaneous nodule in the supraclavicular region?
The treatment involves surgical intervention and antituberculosis therapy.
73
What is the treatment for a chronic, progressive lesion on the nose with a gyrate outline border?
The treatment involves antituberculosis therapy and surgical excision if necessary.
74
What are the typical characteristics of LV plaques?
Softness of the lesions, brownish-red color, and slow evolution.
75
What is the significance of apple jelly nodules in diagnosis?
They are highly characteristic and may be decisive in identifying ulcerated lesions.
76
What does a strongly positive tuberculin test indicate?
It indicates the presence of tuberculosis.
77
What complications can arise from involvement of nasal or auricular cartilage?
Extensive destruction and disfigurement.
78
What is the course of LV without therapy?
It progresses over many years to functional impairment and disfiguration.
79
What is scrofuloderma?
Subcutaneous tuberculosis leading to cold abscess formation and breakdown of the overlying skin.
80
Where does scrofuloderma most often occur?
In the parotideal, submandibular, and supraclavicular regions.
81
What are the clinical findings of scrofuloderma?
It presents as a firm, subcutaneous nodule that is well defined and asymptomatic.
82
What is the histopathological finding in scrofuloderma lesions?
Massive necrosis and abscess formation in the center of the lesion.
83
What confirms the diagnosis of scrofuloderma?
Positive results on culture.
84
What are the characteristic clinical findings of scrofuloderma, and how do they progress over time?
It typically presents as a firm, subcutaneous nodule that softens and leads to ulcers over time.
85
What complications can arise from scrofuloderma, particularly regarding nasal involvement?
Involvement may lead to extensive destruction and disfigurement.
86
What are the characteristics of ulcers in scrofuloderma?
The ulcers are often linear or serpiginous with undermined, inverted, bluish edges and soft, granulating floors. Tuberculin sensitivity is usually pronounced.
87
What complications can arise from scrofuloderma, particularly regarding nasal involvement?
Complications may include involvement of the nasal or auricular cartilage, leading to extensive destruction and disfigurement. Atrophic scarring, with or without prior ulceration, is characteristic, and dry rhinitis may be the only symptom of early nasal involvement.
88
How does the course of lymphadenitis (LV) progress without therapy?
Without therapy, lymphadenitis (LV) is a long-term disorder that progresses over many years, leading to functional impairment and disfigurement. Longstanding LV may result in the development of carcinoma, with squamous cell carcinomas outnumbering basal cell carcinomas.
89
What is the significance of apple jelly nodules in the diagnosis of LV?
Apple jelly nodules are highly characteristic of lymphadenitis (LV) and can be identified through diascopy, revealing a distinctive appearance. Their presence can be decisive in diagnosing LV, especially in cases with ulcerated, crusted, or hyperkeratotic lesions.
90
What histopathological findings are associated with scrofuloderma?
Histopathological findings include massive necrosis and abscess formation in the center of the lesion, which are nonspecific. The periphery of the abscesses typically contains tuberculoid granulomas, indicating an immune response to the infection.
91
What is orificial tuberculosis and what are its clinical findings?
Orificial tuberculosis is a rare form of tuberculosis affecting the mucous membranes and orifices, caused by autoinoculation of mycobacteria from internal organ tuberculosis. Clinical findings include a small yellowish or reddish nodule on the mucosa that breaks down to form a soft ulcer with a punched-out appearance.
92
What complications are associated with BCG vaccination?
Complications include localized reactions at or near the vaccination site, Koch phenomenon in individuals sensitive to tuberculin, regional adenitis, local abscesses, and scrofuloderma with suppuration lasting 6 to 12 months.
93
What is the relationship between tuberculids and tuberculosis?
The relationship is poorly understood; some tuberculids are related to tuberculosis, while others may not be. PCR testing has shown mixed results regarding the presence of M. tuberculosis DNA in skin lesions associated with tuberculids.
94
What is lichen scrofulosorum?
Lichen scrofulosorum is an uncommon lichenoid eruption attributed to the hematogenous spread of mycobacteria in individuals who are strongly sensitive to M. tuberculosis.
95
What is the diagnosis for a painless ulcer on the tongue with undermined edges?
The likely diagnosis is orificial tuberculosis, caused by autoinoculation of mycobacteria from progressive tuberculosis of internal organs.
96
What is the prognosis for orificial tuberculosis?
Orificial tuberculosis usually portends a fatal outcome.
97
What is the histopathology of orificial tuberculosis?
Histopathology shows a massive nonspecific inflammatory infiltrate and necrosis.
98
What is the typical course of BCG vaccination?
An infiltrated papule develops after approximately 2 weeks, attains a size of about 10 mm after 6 to 12 weeks, ulcerates, and then slowly heals, leaving a scar.
99
What is the typical response of papulonecrotic tuberculid lesions to treatment?
Lesions are reported to respond promptly to antituberculosis therapy, regardless of whether a tuberculous focus is identified.
100
What are the clinical findings associated with papulonecrotic tuberculid in children and adolescents?
Lesions are usually confined to the trunk, asymptomatic, firm, and can coalesce to form rough, discoid plaques. They persist for months but may resolve spontaneously.
101
What are the differential diagnoses for papulonecrotic tuberculid?
Differential diagnoses may include conditions associated with discoid lupus erythematosus, arthritis, or erythema nodosum.
102
What is the epidemiology of papulonecrotic tuberculid?
Papulonecrotic tuberculid typically presents as a symmetric eruption of necrotizing papules, appearing in crops and healing with scar formation, preferentially affecting children and young adults.
103
What is the significance of M. tuberculosis DNA in papulonecrotic tuberculid lesions?
M. tuberculosis DNA was detected in approximately 50% of skin biopsies from patients with papulonecrotic tuberculid, indicating a possible link to tuberculosis.
104
What are the characteristics of mycobacteria other than Mycobacterium tuberculosis (MOTT)?
MOTT are widely distributed in nature and are usually commensals or saprophytes, rather than pathogens. They are typically acquired from environmental sources such as water or soil.
105
How do infections caused by MOTT compare to those caused by Mycobacterium tuberculosis?
MOTT seem much less likely to disseminate than M. tuberculosis, and infections usually run a more benign and limited course.
106
What two organisms produce a characteristic clinical picture in infections with atypical mycobacteria?
The two organisms are M. ulcerans and M. marinum.
107
What factors can facilitate infections caused by MOTT?
An immunosuppressed state of the host or damage to a particular organ can facilitate infections caused by MOTT.
108
What are MOTT and where are they typically found?
MOTT are widely distributed in nature and are usually commensals or saprophytes, rather than pathogens.
109
How are atypical mycobacteria usually acquired?
From environmental sources such as water or soil.
110
What is the typical course of infections caused by MOTT compared to M. tuberculosis?
Infections caused by MOTT usually run a more benign and limited course.
111
Which two organisms produce a characteristic clinical picture in infections with atypical mycobacteria?
The two organisms that produce a characteristic clinical picture are M. ulcerans and M. marinum.
112
What factors can facilitate infections caused by MOTT in individuals?
An immunosuppressed state of the host or damage to a particular organ can facilitate infections caused by MOTT, such as in M. kansasii infection of the lung.
113
What is the general treatment response of MOTT compared to Mycobacterium tuberculosis?
As a rule, MOTT are much less responsive to antituberculosis drugs but may be sensitive to other chemotherapeutic agents.
114
What is the relationship between MOTT and skin disease?
MOTT are thought to cause mycobacterial skin disease more often than M. tuberculosis.
115
What type of outbreaks can occur due to atypical mycobacterial infections?
Certain types of exposures may lead to small community outbreaks.
116
What are the characteristics of diseases caused by mycobacteria other than Mycobacterium tuberculosis (MOTT)?
MOTT are typically commensals or saprophytes, acquired from environmental sources like water or soil. They are less likely to disseminate compared to M. tuberculosis and usually cause a more benign and limited course of infection. MOTT are less responsive to antituberculosis drugs but may respond to other chemotherapeutic agents.
117
What is the clinical feature of Mycobacterium ulcerans infection?
Mycobacterium ulcerans infection, also known as Buruli ulcer disease, occurs in wet, marshy, or swampy areas and is associated with contaminated water. It typically presents as a painless subcutaneous nodule that gradually enlarges and eventually ulcerates, exposing necrotic fat. The painless nature of the ulcer is attributed to nerve damage and tissue destruction caused by the toxin mycolactone.
118
What are the risk factors and clinical features of Mycobacterium marinum infection?
Mycobacterium marinum infection occurs in freshwater and saltwater environments, including swimming pools and fish tanks. Risk factors include a history of trauma and water or fish/seafood-related hobbies. The disease typically begins as a violaceous papule at the site of trauma 2 to 3 weeks after inoculation, with possible development of nodules or psoriasiform plaques, usually on the hands, feet, elbows, or knees. Lesions are suppurative and may be multiple in both normal and immunosuppressed hosts.
119
What is the typical presentation of Mycobacterium kansasii infection?
Mycobacterium kansasii is an atypical mycobacterium closely related to M. tuberculosis, usually acquired from the environment. It is more common in individuals with underlying immunosuppression. The infection often presents with papules in a sporotrichoid distribution, and subcutaneous nodules may extend to deeper structures, potentially resulting in carpal tunnel syndrome or joint disease. The lungs are the most commonly affected organ.
120
What are the clinical manifestations of Mycobacterium scrofulaceum infection?
Mycobacterium scrofulaceum infection typically manifests as cervical lymphadenitis, frequently unilateral, in children aged 1 to 3 years. The submandibular and submaxillary nodes are usually involved, and they may enlarge slowly over several weeks, eventually ulcerating and developing fistulas. The disease is generally benign and self-limited, with rare evidence of lung or other organ involvement.
121
What are the clinical features of Mycobacterium avium-intracellulare infection?
Mycobacterium avium-intracellulare infection usually causes lung disease or, less frequently, osteomyelitis. It may present with cervical lymphadenitis that resembles tuberculous scrofuloderma. Clinical features can include painless, scaly yellowish plaques or subcutaneous nodules with a tendency to ulceration. Skin lesions may involve generalized cutaneous ulcerations, granulomas, and infiltrated erythematous lesions, particularly in patients with AIDS.
122
What is the significance of Mycobacterium fortuitum, Mycobacterium chelonae, and Mycobacterium abscessus?
Mycobacterium fortuitum, Mycobacterium chelonae, and Mycobacterium abscessus are fast-growing, facultative pathogenic mycobacteria commonly found in soil and water. They typically cause similar clinical diseases, often following a puncture wound or surgical procedure. Clinical features include a painful red infiltrate at the site of inoculation, with no signs of dissemination or constitutional symptoms, although internal organs may be involved.
123
A patient presents with a painless, undermined ulcer on the lower extremity. What is the likely causative organism?
The likely causative organism is Mycobacterium ulcerans, associated with Buruli ulcer disease.
124
A patient presents with a violaceous papule on the hand after cleaning a fish tank. What is the diagnosis and the causative organism?
The diagnosis is Mycobacterium marinum infection (fish tank granuloma), caused by Mycobacterium marinum.
125
A patient presents with a painless, scaly yellowish plaque on the extremities. What is the likely causative organism?
The likely causative organism is Mycobacterium avium-intracellulare.
126
A patient presents with a painless ulcer on the lower extremity after trauma in a swampy area. What is the causative organism and its unique toxin?
The causative organism is Mycobacterium ulcerans, and the unique toxin is mycolactone.
127
A patient presents with a painless, red infiltrate at the site of a surgical procedure. What is the likely causative organism?
The likely causative organisms are Mycobacterium fortuitum, Mycobacterium chelonae, or Mycobacterium abscessus.
128
A patient presents with a painless, subcutaneous nodule on the hand that later ulcerates. What is the diagnosis and its causative organism?
The diagnosis is Mycobacterium marinum infection (fish tank granuloma), caused by Mycobacterium marinum.
129
A patient presents with a painless, scaly yellowish plaque on the extremities. What is the diagnosis and its associated condition?
The diagnosis is Mycobacterium avium-intracellulare infection, often associated with AIDS.
130
A patient presents with a violaceous papule on the hand after cleaning a fish tank. What is the diagnosis and its histopathology?
The diagnosis is Mycobacterium marinum infection (fish tank granuloma). Histopathology shows suppurative lesions rather than granulomatous ones.
131
A patient presents with a painless ulcer on the lower extremity after trauma in a swampy area. What is the diagnosis and its unique clinical feature?
The diagnosis is Buruli ulcer disease caused by Mycobacterium ulcerans. The unique clinical feature is the painless nature of the ulcer.
132
A patient presents with a painless, red infiltrate at the site of a surgical procedure. What is the diagnosis and its treatment?
The diagnosis is infection by Mycobacterium fortuitum, Mycobacterium chelonae, or Mycobacterium abscessus. Treatment involves appropriate antibiotics based on sensitivity testing.
133
A patient presents with a painless, subcutaneous nodule on the hand that later ulcerates. What is the diagnosis and its treatment?
The diagnosis is Mycobacterium marinum infection (fish tank granuloma). Treatment involves antibiotics such as clarithromycin or doxycycline.
134
A patient presents with a painless, scaly yellowish plaque on the extremities. What is the diagnosis and its treatment?
The diagnosis is Mycobacterium avium-intracellulare infection. Treatment involves antibiotics such as clarithromycin or azithromycin.
135
A patient presents with a violaceous papule on the hand after cleaning a fish tank. What is the diagnosis and its treatment?
The diagnosis is Mycobacterium marinum infection (fish tank granuloma). Treatment involves antibiotics such as clarithromycin or doxycycline.
136
A patient presents with a painless ulcer on the lower extremity after trauma in a swampy area. What is the diagnosis and its treatment?
The diagnosis is Buruli ulcer disease caused by Mycobacterium ulcerans. Treatment involves surgical excision and antibiotics such as rifampicin and streptomycin.
137
What is the primary cause of Buruli ulcer disease?
It occurs in wet, marshy, or swampy areas and is associated with contaminated water.
138
What are the common risk factors for Mycobacterium marinum infection?
A history of trauma and water or fish/seafood-related hobbies and occupations.
139
What is the typical presentation of Mycobacterium kansasii infection?
It often presents with papules in a sporotrichoid distribution and can lead to deeper structures affecting joints.
140
What is the usual manifestation of Mycobacterium scrofulaceum infection in children?
Cervical lymphadenitis, frequently unilateral, mainly in children between the ages of 1 and 3 years.
141
What type of disease does Mycobacterium avium-intracellulare typically cause?
It usually causes lung disease or, less frequently, osteomyelitis.
142
What are the clinical features associated with Mycobacterium fortuitum, Mycobacterium chelonae, and Mycobacterium abscessus?
Infections usually follow a puncture wound or surgical procedure, presenting with painful red infiltrate at the site of inoculation.
143
What are the clinical features and risk factors associated with Mycobacterium ulcerans infection?
- **Clinical Features**:
- Occurs in wet, marshy, or swampy areas, often related to contaminated water.
- Characterized by a painless ulcer that develops from a subcutaneous nodule, which enlarges and eventually ulcerates.
- The ulcer is deeply undermined, exposing necrotic fat.
- **Risk Factors**:
- More common in children and young adults, with a higher prevalence in females than males.
- Associated with exposure to contaminated water.
144
How does Mycobacterium marinum infection typically present and what are the common risk factors?
- **Presentation**:
- Begins as a violaceous papule at the site of trauma 2 to 3 weeks after inoculation.
- Patients may develop a nodule or a psoriasiform plaque, usually on the hands, feet, elbows, or knees.
- Lesions are suppurative and can be multiple.
- **Risk Factors**:
- History of trauma and exposure to water or fish/seafood-related hobbies and occupations.
145
What are the typical clinical manifestations of Mycobacterium kansasii infection and its common risk factors?
- **Clinical Manifestations**:
- Typically presents with papules in a sporotrichoid distribution.
- Subcutaneous nodules may extend to deeper structures, potentially causing carpal tunnel syndrome or joint disease.
- Most commonly affects the lungs, with possible cutaneous infections from nasopharyngeal secretions.
- **Risk Factors**:
- More common in individuals with underlying immunosuppression, such as those with Hodgkin disease, organ transplant recipients, or AIDS patients.
146
Describe the typical presentation of Mycobacterium scrofulaceum infection in children and its clinical significance.
- **Typical Presentation**:
- Primarily manifests as cervical lymphadenitis, often unilateral, in children aged 1 to 3 years.
- Involves submandibular and submaxillary nodes, which enlarge slowly and may ulcerate and develop fistulas.
- **Clinical Significance**:
- The disease is usually benign and self-limited, with rare evidence of lung or other organ involvement.
147
What are the clinical features of Mycobacterium avium-intracellulare infection and its implications for patients with AIDS?
- **Clinical Features**:
- Typically causes lung disease or, less frequently, osteomyelitis.
- Can present as cervical lymphadenitis with sinus formation, resembling tuberculous scrofuloderma.
- Skin lesions may include painless, scaly yellowish plaques or subcutaneous nodules with a tendency to ulceration.
- **Implications for AIDS Patients**:
- M. avium-intracellulare infections are a significant cause of morbidity in patients with AIDS, leading to various skin lesions and systemic complications.
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What are the common clinical presentations associated with Mycobacterium fortuitum, Mycobacterium chelonae, and Mycobacterium abscessus infections?
- **Common Clinical Presentations**:
- These species cause similar diseases, typically following a puncture wound or surgical procedure.
- Patients may experience a painful red infiltrate at the site of inoculation.
- There are usually no signs of dissemination or constitutional symptoms, but internal organs may be involved.
- **Clinical Significance**:
- These infections can lead to localized symptoms and may require surgical intervention if internal organs are affected.
