Dr Peter Gayo Munthali Consultant Microbiologist, UHCW

Honorary Associate Clinical Professor

University of Warwick

Common Infections

Objectives• By the end of this session you will be able to

do the following;• Microbiologically diagnose and treat the

following conditions by using appropriate investigations and by selecting appropriate antibiotics based on scientific rationale;– Central Nervous System infections– Skin and soft tissue infections– Joint infections– Respiratory Tract Infections– Urinary tract infection

Case 1

• A normally fit and well 17 yrs old student is A normally fit and well 17 yrs old student is admitted with 1/7 history of fever, admitted with 1/7 history of fever, headache and nauseaheadache and nausea

• Pyrexia 38.6Pyrexia 38.6ºCºC

• BP 100/69BP 100/69

• HR 120b/minHR 120b/min

• Starts vomiting in A&EStarts vomiting in A&E

• PMHx nilPMHx nil

• SHx nil, lives in halls of residence at SHx nil, lives in halls of residence at Warwick university. Sometimes has Warwick university. Sometimes has alcohol binges at weekends alcohol binges at weekends

• O/E – some mild neck stiffness, slight O/E – some mild neck stiffness, slight photophobiaphotophobia

• Widespread skin lesionsWidespread skin lesions

History & Examination

Considering the history given and examination,

Q1. What is the Diagnosis

a) Sepsis

b) Thrombotic Thrombocytopenic Purpura (TTP)

c) Meningitis

d) Migraine

Q2. Choose 4 most important microbiological investigations and 4 other important investigations to manage the case?

Q3. Name two most important causes of this condition in this age group?

Q4. Which of these antibiotics can be used to treat this condition and state why?

a) Benylpenicillin

b) Gentamicin

c) Meropenem

d) Ciprofloxacin

e) Cefuroxime Q5. What is the role of public health in this condition?

Initial CSF Result on Day 1

More Results on Day 1

(Normal 0.1- 0.4g/l)

(Normal 2.3- 4.5mmol/L)

(Normal 1.1- 2.4mmol/L)

Final CSF Report on Day 3

CSF Findings in Meningitis

Cells/mm³

(0-5)

Gram stain

Bacterial Ag Detection

Protein g/l (N 0.1-0.4)

Glucose mmol/l (N 2.3-4.5)

Viral 10¹-10³ (Lymphocytes)

-Ve -Ve Normal or slightly ↑

Usually normal

Bacterial 10¹-10^4

(mainly polymorphs)

± Ve +Ve High <60% of blood glucose

TB 10¹-10³ (mainly lymphocytes)

± -Ve High or very high

<60% of blood glucose

Note: 5-10% of CSF may be normal in early stages of meningococcal meningitisLactate is increased in bacterial and TB meningitis BUT NOT in viral meningitis

How Do You Adjust WCC in Bloody CSF

• For every 500-700 RBCs, deduct 1 WCC from the WCC

• Examples

RBC 640 x 10^6/L, WCC 4940 x 10^6/L

Corrected WCC 4939 x 10^6/L

RBC 64000 x 10^6/L, WCC 49 x 10^6/L

RBC 64000 ÷ 700 = 91.43

WCC 49-91 = <1

Conclusion WCC is normal

Q3. Name two most important causes of this condition in this age group?

Which of these antibiotics can

be used to treat this condition and state why?

Antibiotic Class Penetration into CSF

Activity(Inhibit)

Comments

Benzylpenicillin/Amoxicillin

Beta lactam (Penicillin)

Yes Cell wall synthesis-Bactericidal

Some pneumococci may be resistant

Ceftriaxone/Cefotaxime

Beta lactam (Cephalosporins)

Yes Cell wall synthesis-Bactericidal

No activity against Listeria monocytogenes

Meropenem Beta lactam (Carbapenem)

Yes Cell wall synthesis -Bactericidal

Gentamicin Aminoglycoside No Protein synthesis- Bactericidal

NEVER to be used

Ciprofloxacin Quinolone No/poorly DNA synthesis- Bactericidal

Vancomycin Glycopeptide Variable Cell wall synthesis-Bactericidal

Chloramphenicol Stand-alone Yes Protein synthesis- Bactericidal/Bacteriostatic

Bactericidal in CSF against pneumococcus, H influenzae and Neisseria meningitidis

Q5. What is the role of public health in this condition?

A 44 year old man is admitted with confusion, fever and change in personality. What is the diagnosis?

What one important laboratory study would you like to confirm the diagnosis?

Causative Organism Duration of Treatment

Meningococcal meningitis ≥ 5 days

Pneumococcal meningitis ≥ 10-14 days*

Haemophilus influenzae meningitis ≥ 10days

Listeria monocytogenes ≥ 10-14 days*

TB meningitis ≥ 12 months*

HSV/VZV Encephalitis ≥ 14-21 days*

Cryptococcal meningitis ≥ 10 weeks*

Treatment Duration

*Longer duration of treatment may be required

Case 2

A normally healthy 40year old man comes in with a two day history of fever, rigors and swollen left knee

Q1. What is the likely diagnosis?

Q2. What two tests can you do to confirm the diagnosis?

LR

Q3. Name two most important causes of this condition?

Q4. What agents would you use to treat this condition

Case 3

25 yr old admitted with T 3825 yr old admitted with T 38ºCºC, right sided abdominal pain and , right sided abdominal pain and dysuria PMH. Admitted with similar condition without abdominal dysuria PMH. Admitted with similar condition without abdominal pain. U&Es: Urea 10.6 Creatinine 170pain. U&Es: Urea 10.6 Creatinine 170

Q1. What is the likely diagnosis ?

a) Ectopic pregnancy

b) Sexually transmitted infection

c) Pyelonephritis

d) UTI

Q2. Which of these investigations will be useful?

a) B/C

b) MSU

c) Pregnancy test

d) Ultrasound scan

Q3. Which of the markers below can help with the diagnosis of this patient?

Q4. Name three most common causes of

this condition?

Case 4

A 66 year old man, unwell for 5 days after returning from holiday in Benidorm, Spain. T A 66 year old man, unwell for 5 days after returning from holiday in Benidorm, Spain. T 3838ºC, ºC, cough productive of small amounts of sputum, mildly confused and short of cough productive of small amounts of sputum, mildly confused and short of breath. Had Amoxicillin 250mg TDS by his GP without improvement. breath. Had Amoxicillin 250mg TDS by his GP without improvement. O/EO/E, , RR 35breaths/minute, Pulse 100b/min, BP 99/60mmHg, Peripheral shutdownRR 35breaths/minute, Pulse 100b/min, BP 99/60mmHg, Peripheral shutdownO2 saturation 90% on 40% O2O2 saturation 90% on 40% O2

Q1. Which of these is the likely diagnosis?

a) Massive Pulmonary embolus

b) Exacerbation of COPD

c) Community acquired pneumonia (CAP)

d) Pulmonary Tuberculosis

Q2. How would you grade the severity of this condition?

Q3. Which bedside/laboratory test can be used to help with diagnosis within three hours?

Treatment?

• PneumococcusPneumococcus– PenicillinPenicillin

• HaemophilusHaemophilus– AmoxicillinAmoxicillin

• LegionellaLegionella– MacrolideMacrolide

Hospital Acquired Pneumonia

• Microbiology– Anticipate Gram negative bacilli

• More resistant

– Less Pneumococcus– Legionella– MRSA pneumonia

Case 5

28 year old male PE instructor , recently travelled 28 year old male PE instructor , recently travelled around US, where he camped in several areas of around US, where he camped in several areas of the country and sustained multiple tick bites. He the country and sustained multiple tick bites. He returned yesterday. On presentation he has returned yesterday. On presentation he has slight erythema around the bite site on left lower slight erythema around the bite site on left lower leg.leg.

Clinical ProgressClinical Progress•While in ED spikes temps up to 39ºC While in ED spikes temps up to 39ºC •He says he has severe pain in leg despite unimpressive He says he has severe pain in leg despite unimpressive erythema of the legerythema of the leg•FY1 reviews patient one and half hours later and notices dark FY1 reviews patient one and half hours later and notices dark erythema spreading up as far as thigh with some blisters erythema spreading up as far as thigh with some blisters developingdeveloping•Patient says he has less pain now than when he presented 2 Patient says he has less pain now than when he presented 2 hours agohours ago•BP 90/50mmHgBP 90/50mmHg

Q1. What is the likely diagnosis?

Q2. Name 5 findings in the clinical history and examination that make this diagnosis likely

A B

C

Q3. Which of these organisms is the likely cause of this condition?

Q4. Name two modalities of treatment?

Gram Stain

Beta haemolytic Group A