1.
Which of the following identifiable risk factors do not suggest vulnerability for developing HUS?
Correct Answer
E. Deranged clotting
Explanation
There are no universally agreed identifiable risk factors for predicting the development of HUS in susceptible individuals. A few studies have shown that fever, leukocytosis, and elevated C-Reactive protein levels may predict progression from STEC infection to HUS
2.
What proportion of children infected with enterohemorrhagic Escherichia coli (STEC) O157:H7 develops HUS?
Correct Answer
A. 5%-15%
Explanation
Approximately 5%-15% of children with STEC infection will develop HUS.
STEC causes a wide spectrum of diseases ranging from asymptomatic carriage through to hemorrhagic colitis and HUS. Faeco-oral transmission is the main route of acquiring new infections, requiring a much smaller bacterial inoculum (
3.
What proportion of children with HUS requires renal replacement therapy (dialysis) in the acute phase?
Correct Answer
C. 40-50%
Explanation
The vast majority of children with STEC-HUS undergo acute kidney injury with 40-50% requiring renal replacement therapy, while a further 2.5% to 10% will either die or develop chronic kidney disease
4.
What is the role of antibiotics during the acute enteric phase of the STEC infection?
Correct Answer(s)
A. Potentially harmful
B. May increase the release of Shiga-like toxins during the diarrheal illness
D. Associated with high mortality and/or longer duration of diarrhoea
E. There are some antibiotics, especially fosfomycin, which may reduce the risk of developing HUS
Explanation
Despite over 40 years of clinical research on HUS, no effective treatment has been developed for STEC-induced HUS.
Clinical practice in relation to the use of antibiotics in the management of STEC-related HUS remains controversial. Antimicrobials may have a potentially harmful role and may increase the risk of HUS in children with E. coli O157:H7 infection with high mortality and/or longer duration of diarrhea, possibly by inducing intestinal production of Stx during the diarrheal phase of the illness. Certain antibiotics, especially DNA-damaging antibacterial agents at sub-lethal concentrations, have been found to increase the release of Shiga-like toxins, and no clinical studies have indicated that antibiotics are effective in reducing the duration of E. coli O157:H7 infection or the duration of diarrhea or bloody diarrhea specifically. Stx genes are carried on bacteriophages, which may be induced into the lytic phase with significantly increased production of Shiga toxins by bacterial DNA damage.
5.
What is the mainstay of management of children with HUS?
Correct Answer(s)
A. Avoid use of antibiotics unless HUS is associated with an entero-invasive species of Shigella
B. Anti-hypertensive therapy may be necessary
C. Blood transfusion to raise haemoglobin up to 70 g/L (not to normal)
D. Avoid anti-motility agents, narcotics and non-steroidal anti-inflammatory drugs during the acute pHase
E. Dialysis may be required if anuria persist longer than 24-48 hrs
Explanation
The mainstay of care for patients with HUS is to provide adequate supportive management including appropriate fluid and electrolyte management, and anti-hypertensive therapy if necessary. Parenteral volume expansion as soon as a patient is suspected to be infected with ETEC 0157:H7 may counteract the effect of thrombotic process before development of HUS and attenuate renal injury (3, 40). Patients with anemia need to be transfused to raise haemoglobin up to 70 g/L (not to normal). Platelet transfusions may also be required for active bleeding or surgery, as well as dialysis for anuria greater than 24-48 hrs. Use of antibiotics, anti-motility agents, narcotics and non-steroidal anti-inflammatory drugs should be avoided during the acute phase.
6.
Non-O157 E. coli may account for up to 20%-50% of all STEC infections?
Correct Answer
A. Yes
Explanation
Non-O157 E. coli refers to strains of E. coli bacteria that do not belong to the O157 serogroup. These strains can also cause Shiga toxin-producing E. coli (STEC) infections, similar to the O157 serogroup. Studies have shown that non-O157 E. coli may account for a significant proportion of all STEC infections, ranging from 20% to 50%. Therefore, the statement "Non-O157 E. coli may account for up to 20%-50% of all STEC infections" is correct.
7.
HUS can also be caused by Shigellosis, Streptococcus pneumoniae, Clostridium difficile, Salmonella, Yersinia, Campylobacter species, varicella, echovirus, coxsackie A and B and human immunodeficiency virus (HIV)?
Correct Answer
A. YES
Explanation
The given statement is true. HUS, or Hemolytic Uremic Syndrome, can indeed be caused by various bacterial and viral infections, including Shigellosis, Streptococcus pneumoniae, Clostridium difficile, Salmonella, Yersinia, Campylobacter species, varicella, echovirus, coxsackie A and B, and human immunodeficiency virus (HIV). These infections can lead to damage to the blood vessels and red blood cells, resulting in the characteristic symptoms of HUS, such as anemia, kidney damage, and low platelet count.
8.
Approximately 5%-10% of all HUS cases have an "atypical" or recurrent course?
Correct Answer
A. YES
Explanation
Approximately 5%-10% of all HUS cases have an "atypical" or recurrent course. This means that a small percentage of individuals with HUS experience a different or recurring pattern of symptoms compared to the typical presentation of the disease.
9.
Causes for aHUS include complement disorders, disorders interfering with the degradation of von Willebrand factor (VWF), the cobalamin metabolism, pregnancy – (HELLP syndrome); drugs such as many chemotherapeutic agents, autoimmune and other disorders?
Correct Answer
A. YES
Explanation
The given statement suggests that causes for aHUS include complement disorders, disorders interfering with the degradation of von Willebrand factor (VWF), the cobalamin metabolism, pregnancy – (HELLP syndrome), drugs such as many chemotherapeutic agents, autoimmune, and other disorders. Therefore, the answer "YES" indicates that the statement is correct and all of these factors can contribute to the development of aHUS.
10.
A small group of aHUS in post bone marrow transplantation period may be caused by immunosuppressive drugs including cyclosporine, or following exposure to herbicides or pesticides and severe scorpion envenomation?
Correct Answer
A. YES
Explanation
The given answer is "YES" because it states that a small group of atypical hemolytic uremic syndrome (aHUS) cases can occur in the post bone marrow transplantation period. This can be caused by immunosuppressive drugs like cyclosporine, as well as exposure to herbicides or pesticides, and severe scorpion envenomation. Therefore, the answer affirms that these factors can indeed cause aHUS in this specific period.
11.
Factors associated with good outcome of renal transplant in patients with non-Shiga toxin-associated HUS (non-Stx-HUS) include:
Correct Answer
E. Presence of membrane co-factor protein (MCP) mutation
Explanation
The outcome of kidney transplantation in patients with genetic HUS is generally poor, with disease recurring in 60% of patients, over 90% of whom develop graft failure.
The presence of factor H (CFH) and factor I (IF) mutations have been associated with a high incidence of graft failure (over 80%), often due to early graft thrombosis (50%) or HUS recurrence within 2 years of transplantation. In contrast, graft outcome is more favorable in all patients who carry MCP mutations.
12.
What is the clinical significance of HUS caused by pathogens other than STEC (including S pneumoniae and HIV)?
Correct Answer(s)
A. They require dialysis therapy more often
B. More likely to require prolonged hospitalisation or have persistent thrombocytopenia
D. Infection caused by S pneumoniae accounts for nearly 40% of cases of non-enteropathic HUS
E. The long-term prognosis for recovery of renal function appears to be good
Explanation
Several studies have shown that patients with D- HUS caused by pathogens other than STEC (including S pneumoniae and HIV) require dialysis therapy more often and are hospitalized or have persistent thrombocytopenia more than twice as long during the acute episode compared with those with D+ HUS. They are also more likely to require platelet transfusions (83% vs 47%) and need more packed red blood cell transfusions (7.8 vs 2.0). Though S pneumoniae-related HUS is associated with a less favorable short-term course than other types of non-enteropathic HUS, the long-term prognosis for recovery of renal function appears to be good in these patients.
13.
How can you describe the most characteristic pathologic processes in HUS?
Correct Answer(s)
A. Shiga-like toxins (Stx-1 and Stx-2) produced by STEC are responsible for the systemic complications of HUS
B. Shiga toxins bind to host cells which express the neutral glycolipid receptors bearing a terminal globotriaosylceramide (Gb3) moiety
C. The basis for the multi-organ system disease in HUS is endothelial cells damage via the inhibition of protein synthesis, activation to produce inflammatory mediators, and amplification of the pro-thrombogenic state
Explanation
The characteristic pathologic findings in HUS are renal endothelial swelling, thrombi in the arterioles and capillaries, and subendothelial fibrin deposits.
14.
What is the case fatality rate of HUS?
Correct Answer
C. Between 2% and 7%
Explanation
HUS has a case fatality rate of between 2% and 7% and a rate of long-term sequelae, such as renal impairment, neurological injury, or hypertension, in 12% to 30% of the cases. Early mortality remains high in pneumococcal-associated HUS (8-fold that of VTEC-induced HUS) as a result of those cases associated with meningitis.
15.
Which of the following statements are true regarding Complications of hus?
Correct Answer(s)
A. Complications in the acute pHase of HUS can include intussusception, renal failure, hypertension, encepHalopathy, pancreatitis and seizures
B. Insulin-dependent diabetes mellitus may present as a long term complication
C. 2.5% to 10% will either die during the acute illness or have permanent renal failure
D. Patients with atypical HUS are more likely to develop complications with recurrent disease episodes, severe hypertension, pancreatitis, hepatitis, cardiac failure, chronic and end-stage renal failure
E. Patients with genetic HUS have an alarmingly high risk of graft loss from disease recurrence or thrombosis
Explanation
Although most patients with typical HUS recover renal functions, recent analysis has shown that typical HUS is not a benign disease in the long term.
16.
Which of the following are not the typical laboratory findings in HUS?
Correct Answer
C. Abnormal prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen levels
Explanation
The typical laboratory findings include a moderate leucocytosis, microangiopathic hemolytic anaemia and elevated reticulocyte count with the presence of schistocytes (fragmented, deformed, irregular, or helmet-shaped red cells) and evidence of thrombocytopenia in the peripheral blood smear. The prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen are within the reference ranges, thus differentiating HUS/TTP from disseminated intravascular coagulation (DIC).
Blood urea nitrogen (BUN) and creatinine are markedly elevated. However, these do not reflect the severity of the renal disease. Urine may contain mild to moderate levels of protein, hemoglobin, haemosiderin, leucocytes and red blood cells.
17.
Which of the following does not represent the main preventive measures and future prospects in the management of huS?
Correct Answer
E. Early antibiotic treatment for patients with STEC infection
Explanation
The best way to prevent HUS is to prevent primary infection with Shiga-toxin-producing bacteria by appropriate personal and public hygiene procedures or through an uptake of appropriately designed vaccines. In addition to the commonly suspected ground (minced) beef, unpasteurized dairy products and contaminated, water person-to-person spread can transmit this pathogen to other people. Secondary prevention through prompt isolation of index cases of ETEC-associated diarrhea is recommended.
Research efforts are currently being directed at the development of vaccines in the prevention of VTEC/STEC infection.
18.
Characteristics of atypical HUS include:
Correct Answer(s)
A. Atypical- or non-Shiga toxin-associated HUS can be either sporadic or familial
B. Up to 50% of cases of aHUS involve abnormalities of the complement regulatory genes including factor H (CFH), membrane cofactor protein (MCP; CD46), and factor I (IF)
C. Other cases are caused by Von Willebrand factor-cleaving protease (ADAMTS 13) mutations, as well as intracellular defect in vitamin B12 metabolism
D. Factor B mutants leading to formation of hyper-functional C3-convertase and mutations of serum thrombomodulin occurs in about 5% of patients with atypical HUS
E. Patients with the CFH mutation have the most severe prognosis, with 60% of them developing end-stage renal disease (ESRD) or dying within one year
Explanation
Atypical- or non-Shiga toxin-associated HUS can occur sporadically or run in families. Up to 50% of cases involve abnormalities in complement regulatory genes such as CFH, MCP, and IF. Other cases can be caused by mutations in ADAMTS 13 or defects in vitamin B12 metabolism. Approximately 5% of patients with atypical HUS have mutations in factor B or serum thrombomodulin. Patients with the CFH mutation have the worst prognosis, with 60% of them developing end-stage renal disease or dying within one year.
19.
Describe some specific clinical prognostic factors for patients with HUS.
Correct Answer(s)
A. The functional state of PMN
B. Duration of anuria or oliguria
C. Renal function assessment for a minimum of one year after HUS should be routinely conducted on all patients
D. Long-term follow-up is required for children with proteinuria, hypertension, abnormal ultrasound and/or impaired GFR at 1 year
E. The presence of factor H (CFH) and factor I (IF) mutations have been associated with a high incidence of graft failure while membrane cofactor protein (MCP) is associated wit a more favourable outcome
Explanation
No specific clinical prognostic factors have been identified for patients with HUS. A marked deactivation of polymorphonuclear (PMN) cells have been detected in severe cases, and the functional state of PMN in HUS patients have been suggested to be of a possible prognostic value (70). D+ HUS patients presenting with oligo-anuria, dehydration, WBC >20 x 10(9)/L and haematocrit >23% are at substantial risk for dying from HUS