Clinical Approach to a Patient with Infection

Question 1

Key history indicators of infection

-travel

Answer 1

Recent travel

• Africa => malaria
• Asia => typhoid
• SE Asia => dengue

When?
-incubation period => time between exposure and symptoms

What?

• business trip, type of accommodation => smaller risk
• backpackers => higher risk

Question 2

Key history indicators of infection

-exposure

Answer 2

Home
-exposure from family members

Animals

• bites => rabies
• pets => scratches (cat scratch disease)

Water
-African freshwater => schistosomiasis

Public
-contact with ill animals, people

Question 3

Key history indicators of infection

-host

Answer 3

Whether the patient has a reduced ability to fight infection

• diabetes (at risk of many infections)
• renal transplant (most common organ to be transplanted)
• liver cirrhosis (innate and adaptive immune system dysfunction)
• absence of functioning spleen (controls RBCs, WBCs, platelets)
• malignancy
• immunocompromised

Question 4

Key features of the physical examination

• what are you looking for
• specific illness signs

Answer 4

General => look unwell
Ears, nose => mainly in children, young adults
Lymph node enlargement => neck, groin
Abdomen tenderness => peritonism?
Skin => cardinal signs?

Life threatening infections?

• sepsis
• meningitis
• pneumonias (bronchial beathing, dull percussion)

Question 5

What considerations should you make when assessing for infection

Answer 5

Do they have life/organ threatening infection?

• rapid assessment, treatment
• IV fluids, surgery, ICU admission?

Patient risk to others?
-do we need to isolate the patient

Do we need to notify Public Health?

Question 6

What is sepsis/septic shock

• what are the key signs and symptoms
• how would you manage this

Answer 6

Abnormal host response to infection => life threatening organ dysfunction

Low BP (systolic<100)
High RR (>22) => SOB
Confusion
Lactate (>2mmol/L)

High/low temp
Low SaO2
Oliguria, high CRT, mottled skin, cyanosis

O2, resucitation IV fluids, Abx, address cause (may need surgery)

Question 7

What is meningitis

• what are the key signs and symptoms
• how would you manage this

Answer 7

Infection of meninges

Classic triad

• Neck stiffness
• Fever
• Confusion

Headaches
Kernig sign => cannot extend leg past 135 when knee and hip at 90 degrees

Supportive therapy, empirical ABx until cause found

Question 8

What investigations would you initiate for suspected infection

• bacterial
• viral
• fungi
• parasites

Answer 8

Bacterial cultures
-Blood, urine, throat swabs

Viral test
-PCR, AB detection

Fungi
-culture, AG or AB detection

Parasites
-blood films, stool samples, ABs in response to parasites

Question 9

Describe the presentation of pharyngitis

• what are the 3 possible differentials, what signs and symptoms would be characteristic of each one
• how would you manage this?

Answer 9

Viral pharyngitis => caused by respiratory virus (rhinovirus)
-red swollen tonsils, throat, constitutional symptoms
=> symptom management

Bacterial pharyngitis => caused by Group A streptococcus
-same as viral
-white patches, swollen uvula
=> symptomatic management + penicilin V

Glandular fever => caused by EBV
-same as viral
-prolonged illness, lymph node swelling
-other symptoms in other systems
=> symptomatic management + rest

Question 10

Describe the presentation of malaria

• signs and symptoms
• travel history
• examination findings

Answer 10

Signs and symptoms

• fever, rigors, headache
• oliguria, vomiting, diarrhea, sweating

Travel

• endemic areas => Africa
• malaria prophylaxis?

Host
-any underlying conditions?

Examination
-fever, looks unwell

Question 11

What 5 investigations would you do for suspected malaria and why?

Answer 11

FBC, blood culture => signs of blood infection
KFT, LFT => signs of organ dysfunction
Blood film for malaria => do this even if they took prophylaxis/vaccinated
HIV test => HIV endemic in Africa

Question 12

How would you differentiate between the 4 main malarial parasites?

• P falciparum
• P malariae
• P ovale
• P vivax

How would you manage malaria

Answer 12

Can differentiate by blood films

P falciparum

• Incubation time => 1-2 wks
• multiple rings in RBC, many RBCs affected
• confusion/fits
• AKF, ARF, acidotic, hypoglycemic
• hyperparasitaemia

P malariae
-Incubation time => 13-40days

P ovale
-Incubation time => 9-18days

P vivax
-Incubation time => 12-17days

IV artesunate or quinine

Question 13

When would you report to Public Health

Answer 13

If infectious disease is suspected

Question 14

Describe the presentation of pneumocystis jirovecii

• History
• Presentation

Answer 14

Often associated with HIV/AIDS
Signs and symptoms
-SOB, dry cough (mucus too viscous to move up, DIFFERENT TO OTHER PNEUMONIAS)
-fever, high RR
-normal breath sounds, lymph nodes ok
-oral candida (immunocompromised

Travel
-from endemic area

Question 15

What investigations would you immediately order for infection in HIV patient?

• what would you see in the CXR of PCP
• how would you manage PCP

Answer 15

Blood cultures => unusual infections
If producing sputum => AFB stain and culture
CD4 count => correlates to susceptibility to opportunistic infections (cryptococcus, CMV)

Routine FBC, LFTs, KFTs => check for organ dysfunction
ABGs

CXR => give you further info
-if abnormalities found => broncheolar lavage for AFB, PCP

PCP
-hazy fine shadowing around hila

Management

• co-trimoxazole (sulfamethoxazole, trimethoprim)
• prednisolone
• O2

Question 16

How would a patient with cellulitis present

• investigations
• likely causative organism
• management

Answer 16

Signs and symptoms

• red hot swollen painful leg
• normally unilateral
• blistered, edema
• fever

Blood culture
Skin swab, blister fluid

Strep pyogenes
Staph aureus

Flucloxacillin or macrolide if allergic