Micro 2 Flashcards
Campylobacter
Reservoir Poultry & Cattle
Transmission Contaminated food
o NOTE: washing chicken breast sprays the Campylobacter around the area
Clinical Presentation: Diarrhoea, bloating and cramps
Ix: Stool Culture
Mx: Supportive
Salmonella
Gram-ve facultative rod-shaped bacterium
Reservoir: Poultry & Reptiles/amphibians
NB: there are 200 strains of salmonella and only 2 are human pathogens, the rest are zoonoses
Transmission: Contaminated food & Poor hygiene
Clinical Presentation: D&V, fever
Ix: stool culture
Management: SUPPORTIVE
Ciprofloxacin & Azithromycin
Bartonella henselae
Reservoir: Kittens > Cats
Transmission: Scratch, bites, licks of open wounds, fleas
Causes 2 disease:
1. Cat Scratch Disease
PC: Macule at site of inoculation -> Becomes pustular + LNs enlarge. If left untreated you get FLAWS.
Ix: Serology (cheap and easy)
Mx: Erythromycin & Doxycycline
this disease can present fairly similarly to other classical clinical presentations such as TB and lymphoma. So Always consider Bartonella in a young person with fever, weight loss and night sweats who has been in recent contact with a cat.
- Bacilliary Angiomatosis (immunocompromised esp HIV - think freddie mercury)
Angio - blood vessels get eroded and burst
PC: Skin papules, Disseminated multi-organ and vasculature involvement (e.g. hepatitis, in head)
Leads to bursting of blood vessels in various organs and tissues. Can be FATAL
Ix: Histopathology & Serology
Management: Erythromycin, Doxy plus Rifampicin
Toxoplasmosis
Reservoir o Cats o Sheep Transmission o Infected meat o Faecal contamination Presentation o Fever o Adenopathy o Still-birth o Infants with progressive visual, hearing, motor and cognitive issues o Seizures o Neuropathy (immunocompromised, presents as ring enhancements on CT )
Investigations
o Serology
Management o Spiramycin o Pyrimethamine + sulfadiazine [Cause risk taking behaviour in mice, high prevalence in schizophrenics] (DO NOT GET A KITTEN WHEN PREGNANT)
Brucellosis
Reservoir: Cattle & Goats
Transmission
Unpasteurised milk / Undercooked meat
For areas where humans still milk the cows: Mucosal splash into their eyes/mouth/nose and Aerosolisation /inhalation
Presentation
Fever – Classically undulant fever (peaks in eve. normal by morn), malaise, rigors, sweating, myalgia/arthralgia, tiredness (incubation 3-4/52)
Orchitis & Focal abscesses (Psoas, liver)
NB looks a bit like TB
Ix: Blood/pus culture, Serology
IMPORTANT: the lab should be warned that the sample being sent may be brucellosis
Management: Doxycycline AND gentamicin OR rifampicin
Coxiella burnettie
Q fever
Think of the netherlands story
Routes: Goat Sheep and Cattle
Aerolisation /inhalation of goat poop, milk of infected animals, unpasteruised milk
Presentation: Pretty much same as the others, Fever, Flu-like illness, Pneumonia, Hepatitis, Endocarditis Focal abscess (para-vertebral, discitis)
Investigations Serology Management Doxycycline (hydroxychloroquine)
Lyssa Virus
Rabies Lyssa Virus • Reservoir Dogs Cats Bats • Transmission o Bites o Scratches o Contact with infected fluid
Presentation
Seizures, Confusion, ?Rabid dog, Agitation,and Aggression Temperature, Confusion, Headaches, Excess Salivation (SCRATCHES)
Paralysis, Delirum and Death
NOTE: once symptoms start, there is a near 100% mortality. BUT there is a 1-3 month incubation period
• Investigations o Serology o Brain biopsy Management (before sx start) - Immunoglobulin - Vaccine If not vaccinated, 3 doses of vaccination and immunoglobulin within 14 days. If vaccinated, only needs post exposure prophylaxis
Rat related zoonoses.
Reservoir: Rats T: Bites, Contact with infected urine or droppings 1. Rat Bite Fever Presentation o Fevers o Polyarthralgia o Maculopapular progressing to purpuric rash o Can progress to endocarditis • Investigations o Joint fluid microscopy and culture o Blood culture • Management o Penicillins
2. Hentavirus Pulmonary Syndrome Reservoir o Deer mouse - Sin Nombre virus o White footed mouse - Sin Nombre virus o Cotton rat - Black canal virus o Rice rat - Bayou virus Presentation o Fever o Myalgia o Flu-like illness o Respiratory failure (in USA) o Bleeding and renal failure (in SE Asia) • Investigations o Serology o PCR • Management o Supportive
Viral Haemorrhagic Fever
4 different types: (resevoir not confirmed)
o Ebola - Bats?
o Marburg - Bats?
o Lass - Rats
o Crimean-Congo Haemorrhagic Fever - Ticks
Transmission
o Contact with fluids of infected
Presentation o Fever o Myalgia o Flu-like illness o Bleeding
Investigations
o Serology
o PCR
Management
o Supportive
Streptococcus pneumoniae
o Gram-positive diplococci, alpha haemolytic o 30-50% of CAP o Acute onset ('rusty coloured sputum') • Severe pneumonia • Fever and rigors • Lobar consolidation o Almost always penicillin-sensitive o Penicillin-resistance strains may be imported from Southern Europe
CAP bacterium
Typical:
Strep pneumoniae
Hib (URTI)
Moraxella Catarrhalis (URTI)
Staph - w/ recent viral infection (EMQs: post-INFLUENZA infection) ± cavitation on CXR
Klebsiella Pneumoniae - Alcoholism, elderley. Haemoptysis
Atypical (organisms without a cell wall) Legionella Mycoplasma Coxiella Burnetti Chlamydia Psittaci
CAP organisms by age
0-1 months • Escherichia coli • Group B Streptococcus • Listeria monocytogenes 1-6 months • Chlamydia trachomatis • Staphylococcus aureus • RSV 6 months - 5 years • Mycoplasma pneumoniae • Influenza • Chlamydia pneumoniae
16-30 years
• Mycoplasma pneumoniae
• Streptococcus pneumoniae
How do we know if a pt’s pneumonia is severe
o Confusion o Urea > 7 mmol/L o RR > 30 o BP < 90 systolic, < 60 diastolic o 65+ years Interpretation 2 = consider admitting 2-5 = manage as SEVERE pneumonia, consider ITU
Bronchitis
DEFINITION: inflammation of medium-sized airways Mainly occurs in smokers Presentation o Cough o Fever o Increased sputum production o Increased shortness of breath • CXR is usually NORMAL • Organisms o Viruses o Streptococcus pneumoniae o Haemophilus influenzae o Moraxella catarrhalis • Treatment o Bronchodilation o Physiotherapy o Antibiotics
Causes of cavitation on CXR
o Staphylococcus aureus
o Klebsiella pneumoniae
o TB
Haemophilus Influenzae
- Gram-negative cocco-bacilli “looks like snot on a piece of paper”
- 15-35% of CAP
- More common with pre-existing lung disease
- May produce beta-lactamase
Legionella
T: Aerosol spread & Environmental outbreaks
PC:
• Confusion
• Abdominal pain
• Diarrhoea
o Lymphopaenia
o Hyponatraemia
Can cause multi-organ failure
Ix: urinary antigens, It is grown on a buffered charcoal yeast extract
Mx: Atypical so needs a protein synthesis inhibitor, Sensitive to macrolides and tetracyclines
Atypical pnuemoniae features
- Flu-like Prodrome before fever and pneumonia
- Extra-pulmonary charactersitics hepatitis, hyponatraemia
What should you consider when pts are failing to respond to pneumoniae tx?
• Empyema/abscess (abscesses are walled off and even if the abx can penetrate they are very acidotic and abx will be in@) • Proximal obstruction (tumour) • Resistant organisms (travel is important) • Not receiving/absorbing antibiotics • Immunosuppression • Other diagnosis o Lung cancer o Cryptogenic organising pneumonia
TB
• Must always be considered as a differential
• Clues
o Ethnicity
o Prolonged prodrome
o Fevers
o Weight loss
o Haemoptysis
Ix:
CXR- Classically upper lobe cavitation (but can vary)
Staining- An auramine stain and a Ziehl-Neelsen stain will be done. Red rods are the acid-fast bacilli
HAP
• A pneumonia onset > 48 hours in hospital
• Patients have often had previous antibiotics and maybe even ventilation
• Bronchial lavage is desirable to differentiate upper respiratory from lower respiratory flora
• Aetiology of HAP
o Enterobacteriaciae (e.g. E. coli, K. pneumoniae)
o Staphylococcus aureus
o Pseudomonas spp
o Haemophilus influenzae
o Acinetobacter baumanii
o Fungi (Candida spp)
PCP
Pneumocystic jirovecii pneumonia • Protozoan • Ubiquitous in the environment • Insidious onset Presentation o Dry cough o Weight loss o SOB o Malaise NOTE: the walk test (attaching an oxygen saturation probe and asking the patient to walk) will show desaturation on exertion • CXR - bat wing shadowing • Investigations: bronchoalveolar lavage • Treatment: co-trimoxazole (septrin) • Prophylaxis: co-trimoxazole
Aspergillosis
1. Allergic bronchopulmonary aspergillosis o Chronic wheeze o Eosinophilia o Bronchiectasis 2. Aspergilloma o Fungal ball, often in pre-existing cavity o May cause haemoptysis 3. Invasive aspergillosis o Immunocompromised o Treatment: amphotericin B
Signs: non-specific (interstitial) changes on the CT scan, neutropenia
What organisms can immunosupppressed pts get in lower RTI?
- HIV: PCP, TB , Atypical mycobacteria
- Neutropenic pts: Fungi e.g. Aspergillus spp.
- Bone Marrow Transplant: CMV
- Splenectomy: Encapsulated organisms (S. pneumoniae, H. influenzae, malaria)
Anything can do anything