Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

STEP Pathology > deck_5376786 > Flashcards

deck_5376786 Flashcards

1
Q

What is osteomyelitis?

A

infection localized to bone characterized by bone destruction, formation of sequestra (dead bone) caused by production of local inflammatory mediators that promote necrosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the most common cause of OM? Why?

A

Staph aureus because it expresses high-affinity adhesions to components of bone matrix that express fibronectin, laminin, and collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does OM present?

A

can get vague symptoms including non-sepecific pain around the involved site with absence of systemic signs (i.e. fever/chills, local swelling, erythema around site UNCOMMON but can be seen)-draining sinus tracts can present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is OM diagnosed? Standard of care for diagnosis?

A

in a radiograph, you might be able to see abnormalities 10-14 days after infection onset. However, MRIs (below) and CT are considered SOC (expensive, but very sensitive)- will show inflammation and bone destruction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why are sequestra formed?

A

infection in the bone leads to an increase inintramedullary pressure due to inflammatory exudates,vascular thrombosis ensues andbone necrosis follows due to lack of blood supply=sequestra are formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Diagnosis rules for OM

A

IDing the organism is important to help optimize medical therapy (best accomplished by surgical sampling or needle aspiration using radiologic guide to obtain tissue for pathology and culture)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Common causes of OM?

A

-common (S. aurues, Coag neg staph (S. epi))-some (Streptococci, Enterococci, MTB,anaerboes)-rare (dimorphic fungi)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

OM caused by someone stepping on a nail is most likely _____

A

Pseudomonas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Treatment of OM?

A

Remove hardware, drain/debride and start ABX

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

ABX DOC for OM?

A

-B-lactams (Cephalosporins and penicillinase-resistant penicillin commonly used due to low toxicity profile and spectrum of activity) and Vanc commonmost given 4-6 weeks of IV therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Other options for OM ABX?

A

-Linezolid for strep, staph, and VRE-Dapto against gram+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

AE of Linezolid?

A

Prolonged use has been associated with significant pancytopenia (esp thrombocytopenia), peripheral neuropathy, optic neuritis, and lactic acidosis.Use has been limited to patients with VRE or patients who are intolerant of Vanc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How can vertebral osteomyelitis and spondylodiskitis occur?

A

these infections of intervertbral disks and adjacent vertebrae can arise from skin/soft tissue infection, GU tract infection, infective endocarditis, or post-operatively

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do vertebral osteomyelitis and spondylodiskitis present?

A

localized insidious pain/tenderness in spine area in 90% of patients, with fever sometimes, and nerve root compression/motor deficiencies common in only about 15% of patients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Most common causes of VO and spondylodiskitis?

A

S. aureus and Coag-neg staphand MTB and Brucella in endemic regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Diagnosis of VO or spondylodiskitis?

A

MRI is very useful in establishing diagnosisImage-guided percutaneous biopsy sometimes helpfulIf an epidural abscess (abscess enclosed within confines of spinal column, picture next slide) is present, it should be drained if possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Osteopathies are common in DM and are commonly the result of vascular insufficiency. Why?

A

Neuropathy, vascular insufficiency and hyperglycemia lead to variety of consequences that lead to development of skin ulcer and osteomyelitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What factors increase the risk of foot ulcers in DMs?

A

DM for 10+ years, poor glucose control, CV disease, retinal or renal complications, peripheral neuropathy, evidence of increased local pressure (callus), PVD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Treatment of ulcers in DM?

A

-debride, revasculization-Broad-spectrum ABX required (zosyn, entrapenem, cephalosporins, quinolones)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Acute hematogenous osteomyelitis in children most commonly occurs where?

A

•Involves mostly metaphyses (due to its weird anatomy) of long bones with tibia or femur affected in most cases.–Half of cases of neonatal OM also have involvement of adjacent joint with septic arthritis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What causes acute hematogenous osteomyelitis in children?

A

Capillary ends of the nutient artery make sharp loops under the growth plate and feed into large venous sinusoids where blood flow becomes slow and turbulent. Obstruction of these capillaries (due to any minor trauma) can lead to areas of avascular necrosis and allow the entry of bacteria

22
Q

Most common causes of acute hematogenous OM in children?

A

S. aureus and S. pneumoniaeand GBS and E. Coli in neonates

23
Q

How is AHOM in children treated?

A

mostly cases with 3 weeks of ABX with switching to PO only when the patient becomes afebrile

24
Q

What are the common causes of OM in SCD?

A

Salmonella and S. aureus are the most commonMOST patients are children

25
Q

Why does OM occur in SCD?

A

–Capillary occlusion secondary to intravascular sickling may devitalize and infarct the gut, permitting Salmonella invasion. Reduced function of the liver and spleen suppresses clearing of these organisms from the blood stream–Bone is also devitalized and serves as a nidus of infection

26
Q

OM in IVDU is common BUT the sites impacted are abnormal and thus good clues. What are some sites commonly affected by IVDU and not typical OM?

A

sternoclavicular, sternochondral joint, pubic symphysis

27
Q

Most common pathogens of OM in IVDU?

A

S. aureus, Pseudomonas, and CandidaEikenella corrodens, normal oral flora bacterium, can cause OM in IVDU who lick the needle tip or skin before infection (“needle licker osteomyelitis”)

28
Q

MTB OM usually affects where?

A

•MTB osteomyelitis often affects the spine andmost cases are the result of hematogenous spread from a pulmonary source

29
Q

How does MTB OM present?

A

•Clinical: Pain and swelling with abscess and sinus formation•Vertebral osteo (Pott’s disease): among most common osteoarticular manifestations of TB.–Systemic symptoms often absent. Back pain/stiffness commonly only symptom

30
Q

Diagnosis of MTB OM? How commonly does this happen in MTB infection?

A

Occurs in1-5% of cases of TB.Significant overlap in imaging appearances between TB OM and other forms of OM exists. Diagnosis should rely on presence of MTB in culture or stain. CXR abnormal in less than 50% of patients with MSK TB but should always be obtained.50% of patients: MRI shows paravertebral soft tissues abscess in addition to bone lesion.

31
Q

What is this?

A

Pott’s Disease

32
Q

What is myositis?

A

general term for inflammation of the muscles (uncommon in skeletal muscle) that can be caused by any type of microbe (bacteria, virus, fungi, etc.)

33
Q

How can myositis occur?

A

Bacteria invade muscle from either contiguous sites of infection (skin/subcu abscesses, penetrating wounds, decubitus ulcers, osteomyelitis) or by hematogenous spread from a distant focus

34
Q

How does bacterial pyomyositis present?

A

–Most commonly caused by S. aureus–Pus accumulates within muscles initially–Clinically characterized by fever, localized muscle pain and stiffness/swelling/tenderness

35
Q

Most cases of pyomyositis occur where globally?

A

Most cases occur in the tropics; in more temperate areas it is very uncommon

36
Q

Note about pyomyositis

A

Bacteremic spread of infection to skeletal muscle extremely uncommon. Among fatal cases of staph sepsis, abscesses in skeletal muscle are found in less than 1% of patients.infection is not usually due to primary infection of adjacent skin, soft tissue and bone (i.e. this infection occurs in the absence of a predisposing site of infection)

37
Q

What is the pathogenesis of pyomyositis?

A

–Previous bacteremia, commonly asymptomatic and transient along with (likely) some minor muscle trauma or injury

38
Q

How does pyomyositis present?

A

Fever, distinct muscle tenderness and swelling with warm overlying skin; pus can be aspirated. If patient is not diagnosed, sepsis can develop along with striking erythema, exquisite tenderness and fluctuance.

39
Q

What are the risk factors for pyromyositis?

A

HIV, IVDU, DM, alcoholic liver disease, corticosteroid therapy, hematologic malignancies (leukemia, lymphoma, multiple myeloma)Postpartum, postabortion and postop states are rare predisposing risk factorsHIV/AIDS: repeatedly reported and usually due to S. aureus. Predisposition relates to granulocyte dysfunction, progressive cell-mediated immunodeficiency, and possible muscle injury (HIV myopathy, HAART side effects, myositis from parasitic disease)

40
Q

What the most common sites for pyomyositis?

A

large muscle of LEs and trunk muscles including the shoulder

41
Q

Most common causes of pyomyositis?

A

–S. aureus causes 60-70% of cases in temperate areas–Group A Strep 1-5%

42
Q

How is pyomyositis diagnosed?

A

•X rays may show presence of swelling or gas in soft tissue•Ultrasound may show focal abscess formation•MRI the best: identifies focal muscle edema, localizes presence of focal abscesses

43
Q

Treatment of pyomyositis?

A

–Drain the abscesses–Initial antibiotic therapy should include Vancomycin

44
Q

What causes gas gangrene?

A

Clostridium perfringens (can also cause food poisoning)

45
Q

What is the structure of CP?

A

Alpha toxin is a hemolytic toxinAnaerobic gram positive rod

46
Q

How is CP found? How does transmission occur?

A

–Clostridial spores are located in the soil; vegetative cells are members of the normal flora of the colon and vagina. Transmission through wound contamin.

47
Q

What happens once CP enters deep tissue DIRECTLY from soil after trauma?

A

–Organisms grow in traumatized tissue (especially muscle) and produce variety of toxins, most importantly alpha toxin (lecithinase) – damages cell membranes, including erythrocytes which results in hemolysis. Enzymes produce gas in tissues.Trauma introduces organisms (vegetative or spore forms) directly into deep tissue. If trauma compromises the blood supply, an anaerobic environment forms with low oxidation-reduction potential and acidic pH, which is optimal for growth of clostridial organisms. Necrosis progresses within 24 to 36 hours of the traumatic injury.

48
Q

How does gas gangrene present?

A

•Pain, edema, cellulitis and gangrene (necrosis) are present.•Crepitus indicates presence of gas in tissues.•Hemolysis common.•Shock and death occur; high mortality.

49
Q

How is gas gangrene diagnosed?

A

•Smears of tissue and exudate show large GPRs. Spores not usually seen.•Organisms cultured anaerobically and then identified by sugar fermentation reactions and acid production•Exhibit double zone of hemolysis on blood agar.

50
Q

Treatment of gas gangrene?

A

Pencillin G

STEP Pathology (80 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions