InfectIons

Infections disease is a common cause of morbidity and mortality.

Infections is classified into viral, bacterial, fungal and parasitic.
VIral InfectIons

Encephalitis & meningitis:

• The most important causes are TB meningitis; and rabis (zoonotic disease
from dogs).
• Clinical picture of T.B meningitis:
1. Severe systemic manifestations more than bacterial (high grade fever
Fever, vomiting, lethargy, myalgia and arthralgia, Purpura fulminans
or erythematous rash, disseminated intravascular coagulopathy)
2. TB meningitis should be considered in any case of aseptic meningitis.

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 3. CSF examination: lymphocytosis and increase protein content
(Dr. Amira: despite viral infection causes lymphocytosis with low
protein content)

Pharyngitis: adenovirus, EBV and cytomegalovirus (CMV)

• EBV causes generalized lymphadenopathy; so, it is a differential
diagnosis with other causes of generalized lymphadenopathy as lymphoma
and TB the most common causes and should be excluded
• EBV & CMV are non hepatotropic virus and may cause acute hepatitis
and diagnosed after excluded other viruses.
• Cytomegalovirus: is one of the commonest causes of a transplant
rejection post transplantation rejection of the kidney (hemodialysis post-
transplant).
• MCQ: Patient had rejection after renal transplantation, what is the most
cause: CMV.
• EBV and CMV may present with HIV coinfection.
• EBV may be pre-carcinogenic in lymphoma.
Cardiovascular: Coxsackie B virus
• May cause acute pericarditis or acute myocarditis.
• Acute pericarditis:

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 1. The patient may be presented by persistent acute chest pain (not
responding to nitroglycerine, aspirin or O2; BUT responds only to
analgesic) and ECG shows elevated ST segment in all leads and the
cardiac enzymes are normal.
2. Treatment: the patient is admitted to ICU with analgesic, oxygen and
the control of temperature.
3. Complication: after three or four days, the patient developed
progressive dyspnea and the pericardial effusion.
• Acute myocarditis: 28 years old female presented with acute heart failure.

N.B: Cardiac enzymes are elevated in angina and myocardial infarction

and normal in acute pericarditis.

Hepatitis: Hepatitis markers

• HCV: HCV Abs means the patient had immunity but not definitely
exposed to recent infection. So, we need to make PCR to confirm the
infection.
1. +ve HCV Abs & -ve PCR: exclude chronic HCV.
2. -ve HCV Abs & +ve PCR: acute HCV (as antibodies take 12 weeks
to be formed).
Ex: patient presented by acute hepatitis after exposed to blood of an infected his
mother 1 day ago & you suspect the patient may have viral transmission from the
mother. The investigations will show -ve HCV Abs (as there was no immune
response after 1 day) but +ve PCR.
• HBV
1. Recent infection (1 day): -ve HBsAg; and +ve HBV DNA PCR.
2. The HBV differs from HCV in latent infection (window period)
3. Window period: time in which HBsAg is absent (-ve); and PCR is
not yet +ve; but there is +ve HBcAb IgM & IgG.
4. Window period serology: +ve HBcAb IgM or IgG; -ve HBcAg; -ve
HBsAg; HBV DNA PCR shows low viremia or not yet detected but
after 2 weeks will be +ve.

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 5. Occult HBV (Dr Amira said it after the lecture): -ve HBsAg; -ve
HBsAb; +ve HBcAb IgM; may be -ve HBcAb IgG; low viremia in
PCR.
Infection HBsAg HBeAg HBcAb HBsAb DNA PCR
Recent - + - - +
Acute + + + (IgM) - +
Window - + (IgM or + or -
IgG)
Chronic + + (IgG) - +
Occult - + (IgM); - + (low
- (IgG) viremia)
Recovery - - + (IgG) + -
Immunization - - + -
The table is from medscape.com “Hepatitis B Test” except the occult type.
Watch this for more details:
https://youtu.be/3e7WdGv_0HQ?si=qUWB4CGPBItuQ0Bo
• Hepatitis markers are very important clinical application in patient
before receiving biologic therapy (e.g. IL or TNF blockers).
1. As in patients with SLE not responding to steroid, or patient with IBD
or rheumatological disease and need biological therapy
2. Patients must make sure that hepatitis markers especially HBV are
negative to avoid any complications in sense of reactivation of the
virus.
3. We order HBsAg, HBcAb (IgM & IgG). If both are -ve there is no
need for PCR. And QuantiFERON test to exclude TB.
4. HBsAg is not enough alone before giving biologic therapy.
N.B. The general rule is any recent viral infection with in first days of infections,
the antibodies may be -ve but the PCR is +ve.
MCQ: if Abs are -ve & PCR is ordered but the result is not available now, this
doesn't mean that the patient has not get infected.
HIV

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 • After 2 weeks from sexual intercourse the patient complains of flu-like
symptoms: fever, sweat, myalgia, bone aches, fatigue and etc. CBC shows
leukopenia. HIV Ab is -ve then do HIV PCR to confirm the infection.
• The doctor mentioned that HIV is an important topic (will be discussed in
the second lecture).
Pneumonia
Influenza, parainfluenza, adenovirus, RSV, and SARS-COVID: self study.
• Classification according to site: lobal or lobular (bronchopneumonia);
unilateral or bilateral.
• Classification according to etiology: hospital acquired, or community
acquired.
• The viral pneumonia usually presents with bronchopneumonia.
Gastroenteritis
The doctor mentioned it is an important topic: self study.
Pancreatitis: Coxsackie B virus
• The patient may present by acute pancreatitis without dyslipidemia,
hypertriglyceridemia, gall stones, autoimmune disease, or any visable cause;
so, it may be from viral infection as Coxsackie B virus.

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 BacterIal InfectIons

Bacterial meningitis
• Strept pneumonia, N. Meningitis, H. influenza are the most common causes
of bacterial meningitis.
Pneumonia
• Bacterial pneumonia presents with lobar pneumonia.
• Case of bacterial pneumonia: cough, high-grade, fever, auscultation shows
bronchial breathing in the left lower lobe, dullness by percussion,
diminished air entry, crepitations & vocal resonance.
Pneumonia: TB
• It has two main problems: multiple strains; and the multi-drug resistance
(MDR), and a new strains with extensively drug resistance (XDR)
• TB is one of the commonest cause of fever of unknown etiology.
• Clinical presentation

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 1. TB meningitis: do CSF examination
2. Addison: if TB affects the adrenal gland.
o Patient with generalized fatigue with past history of TB treated
but he stopped treatment before consultation now present to the
emergency with shock, hypotension, hypoglycemia. The
diagnosis is Addison secondary to TB
3. TB osteomyelitis (Pott’s disease of the spine): the patient present
with tingling numbness, radicular pain and MRI shows Pott’s spine.
4. Psoas abcsess.
5. TB pneumonia.
6. TB hepatitis (rare).
7. TB peritonitis: Patient with ascites, no liver cirrhosis no
splenomegally, no bilhariziasis. U/S shows liver is average size and
homogenous, and the spleen is average size. Aspiration of ascitec
fluid shows exudative fluid.
8. TB enteritis (Ileitis): is common and presents with gastroenteritis
with lymphadenitis.
9. TB lymphadenitis.
Exudative fluid Transudative fluid
Protein amount High Low
High with predominance
of polymorph nucluear
cells in bacterial
Type of cells Low amount of cells
infection; and
lymphocytes in TB
infections.

Fever of unknown origin side discussion is in the next pages.

Urinary tract infection

Case 1: female 78 years old complaining of frequency, urgency, fever. Urine
analysis revealed pus cells 100. Urine culture shows bacterurea more than 100,000
CFU. So the diagnosis is significant bacteria.

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Case 2: 60 years old male patient presents with disturbed conscious level (DCL),
dehydrated, feverish, electrolyte disturbance.
N.B. DCL in Case 2 is due to dehydrated, feverish, electrolyte disturbance. But
UTI may present with DCL alone in patients above 82 years.

Case 3: female 20 years old burning maturation, dysuria, frequency no fever.

Urine analysis revealed pus cells. Urine culture detect no organism. So, the patient
has sterile pyuria for differential diagnoses.
N.B. Differential diagnoses to sterile pyuria are atypical organism such as TB; or
the use of antibiotics.

Gastroenteritis
• When to suspect food poisoning vomiting, abdominal pain, high grade fever,
diarrhea.

Case 4: 13 years old child ate from Karam Elsham presents with high-grade fever
(39), vomiting, bloody diarrhea. Later he developed very high-grade fever, severe
right hypochondrial pain then become generalized, elevated liver enzymes, with
tenderness hepatomegally. So, the diagnosis is pyogenic liver abscess.
N.B. DD of bloody diarrhea are dysentery, shigella, E. Coli.
N.B. HAV fever is responsible to treatment.

Case 5: 11 years old child ate pizza in the North Cost, presents with fever,
vomiting, diarrhea. A doctor gave him treatment then 6 days later he developed
high-grade fever, severe right hypochondrial pain. Liver abscess was treated for 3
months with no improvement. Aspiration of the abscess with culture and
sensitivity revealed Staph. Aureus.
N.B. Staph. aureus is very pyogenic virulent organism and may cause multiple
pyogenic liver abscesses.

Infective endocarditis
• S. aureus one of the organisms which causes acute infective endocarditis in
HIV patients and IV drug addict.

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 • Acute infective endocarditis cannot be detected by trans thoracic echo
instead transoesophageal echo must be done.
Case 6: 21-year-old patient present by fever of unknown etiology leukocytosis,
high ESR. All investigation is normal. History of heroin injection discovered
accidentally after bleeding from femoral vein. The case is acute infective
endocarditis by S. aureus. Bacteria is not detected in the blood culture as the
patient is undercover of antibiotic. Trans-esophageal echo that shows vegetation in
the right side of the heart.
N.B. Negative blood culture does not rule out patient is safe.
N.B. Good doctor patient relationship is very important to build the trust.

Acute infective endocarditis Subacute infective endocarditis

• S. aureus • In left side of the heart
• In Rt side of the heart. • Patient is known to be cardiac
• Patient not known to be cardiac • Blood culture is +ve.
• Blood culture may be -ve. • Valve affection in left side
• Transthoracic echo is -ve. • Trans thoracic echo: vegetation
• Trans oesophageal echo: on the mitral valve
vegetation on tricuspid valve. • TTT/broad spectrum antibiotic
• TTT/ anti staph (penicillin in high dose).

Fever of unknown origin

• Patient with fever more than 38.3 for more than 3 weeks without a
provisional diagnosis.
• CBC, LFT, KFT, chest X-ray, ultrasound all are normal; but ESR is more
than 100. So, we do hospital admission and do all investigations.
• All diseases may present with fever of unknown origin.
• It is not due to the disease is unknown. it is a common disease but the
presentation is atypical.
• Fever of unknown etiology not diagnosed , no treatment.

Case 7 fever of unknown origin: patient work as a farmer with BMI more than 35
present with fever more than two months. Examination and investigation are

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normal CBC, LFT, KFT, but ESR is 120 (ESR elevation never discharge
patient). CT chest and abdomen CSF examination, blood culture abdominal
ultrasound CT brain all are negative. Temperature chart between 37.5 and
38.5. The patient start to complain that he cannot move his right leg. Negative LN
examination finally we ask it MRI spine that indicates Pott’s spine, TB psoas
abscess. If the patient was discharged before diagnosis, the Potts disease can lead
to serious complication such as miliary TB & TB peritonitis or steroid intake will
lead to transformation of close to open TB that become infective.
N.B. Open (active) TB can infect 300 person in the same place}
N.B. After diagnosis of TB & HIV we must inform ministry of health (MOH).
N.B. once I diagnosed TB must inform MOH and screening for his family to
prevent transmission of infection.
N.B. patient with fever of unknown etiology should be examined every day
morning and night.

Case 8 (open TB ): female underbuilt 18 years old present with very irritative
cough, sputum, fever 39°C, sweating, toxic look. chest X-ray reveals typical
picture of TB with Ghon’s focus and cavity. Her baby is suffering from diarrhea.
We fear that the baby got infected by TB from his mother. Chest X-ray was done
for the baby that reveals typical picture of TB.
N.B. TB, HBV, HIV take care from mode of transmission in pregnant woman to
the fetus. Ex. she had acute hepatitis B and the baby is jundiced. You can protect
the baby before delivery from acquiring the infection from mother.

If a person want to know if he has immune response towards HBV or not

• Ask him to do HbsAb then if the titer is less than 100 take a booster dose.
• HbsAb must be done also to contact with infected case (the other partner and
the children).
• All health care providers must be immunized against HBV.
• HBV is more infectious than HIV as it infects with low viremia but HIV
need high viremia
• There is a vaccine to HBV, but there isn’t a vaccine for HCV.

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 Viral hemorrhagic fever (VHF)

• Causes endemics in Africa and Asia.

• Caused by viral infection as Ebola virus, Dengue and Marburg.
• Very high mortality.
• TTT: is supportive, not antiviral drugs.
• Clinical multi-system illness associated with fever & bleeding diathesis
(tendencies) caused by several distinct families of viruses.
o Initial nonspecific prodromal stage
o Fever (high-grade fever)
o Malaise
o Headache
o Myalgia/ arthralgia
o Abdominal pain
o Non-bloody diarrhea which transforms later to bloody
• Then Progresses to more severe symptoms & death
o Hemorrhage (not all cases)
o Increased vascular permeability
o Hypotension and Shock
o Multi-organ failure

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 • Many cause rapidly progressive illness & high mortality.

• IP 2-5 days
• After five days, cytokine release and bleeding per orifices as hematemesis
bleeding per rectum. At this time, give supportive treatment as we fear of
cytokines storm.
• May progress to severe symptoms, hemorrhage, hypotension, shock, multi
organ failure.
• Another examples as rift valley fever in Egypt (‫)الشرقية‬.

Yellow fever
• Yellow fever is common in Africa
• Any person traveling to Africa should be vaccinated against yellow fever.
• The only virus of viral hemorrhagic fever that have vaccine is yellow
fever.
• Clinical picture of yellow fever includes flu like symptoms (fever, malaise
lymphadenopathy) then progressed to bleeding.

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• Diagnosis: antibodies, PCR, antigen isolation from blood. Antibodies is
commonly used in Africa because PCR is not found in many facilities in
Africa.
• Transmission occurs by person-to-person infection or vector transmission by
monkey mouse and bat.

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