Microbiology 2 and 3 - Microbiology of the Resp. tract Flashcards
What are the causes of the classical flu?
Influenza A virusInfluenza B virus
What is the cause of a flu like illness?
Parainfluenza viruses but many other causes
Does haemophilus influenzae cause flu?
Not a primary cause (it is a bacterium) but may be a secondary invader
Complications of flu?
Primary influenzal pneumoniaSecondary bacterial pneumoniaBronchitisOtitis mediaInfluenza during pregnancy may also be associated with perinatal mortality, prematurity, smaller neonatal size and lower birth weight
How is flu treated?
Symptomatic (bed rest, fluids, paracetamol)Antivirals (only if patient is at risk of complications and when flu is circulating and early in disease)
What antivirals are used to treat flu?
OseltamivirZanamivir
What are epidemics of flu associated with?
WinterMinor mutations in the surface proteins of the virus (antigenic drift)
What is the difference between epidemic and pandemic?
An epidemic occurs when a disease affects a greater number people than is usual for the locality or one that spreads to areas not usually associated with the disease. A pandemic is an epidemic of world-wide proportions.
What type of flu can cause pandemics?
Influenza A only
What subtype of influenza A is avian flu?
H5N1
How is influenza confirmed in the lab?
Direct detection of virus:PCR (nasopharyngeal swab, throat swab or other respiratory samples)Other labs/ hospitals may used immunofluorescence, antigen detection (near patient)
Prevention of flu?
Killed vaccine (given to adult/ child (aged 6 months to 2 years) patients at high risk and healthy care workers)Live attenuated vaccine (more effective than killed vaccine in children aged 2-17, given to ALL children aged 2-5 and all primary school children administer intra-nasally)
When are antivirals used as a prophylaxis against flu?
After a contact with fluVery rarely
What are 3 examples of atypical pneumonia?How are these treated?
Mycoplasma pneumoniaeCoxiella and Chlamydohila psittaciTetracycline and macrocodes e.g. clarithromycin
Mortality of atypical pneumonias?
Varies with pathogen by generally lower than classical bacterial pneumonia
How are the atypical pneumonias (mycoplasma, coxiella, psittaci) diagnosed?
By serology (send acute and convalescent bloods to lab)Virus detection (PCR on respiratory swabs/ secretions)
Who tends to get mycoplasma pneumoniae?
Children and young adultsPerson to person spread
What diseases does coxiella burnetti cause?
PneumoniaQ-fever
what is infection with coxiella burnetti associated with?
Sheep and goats
Complications of infection wit coxiella burnetti?
Culture negative endocarditis
What illness does infection with chlamoydophila psittaci cause?How does this usually present?
Psittacosis (parrot fever)Pneumonia
What age do patients present with bronchiolitis?Symptoms
1st or 2nd year of lifeFeverCoryzaCoughWheezeSevere cases can cause grunting, decreased PaO2, intercostal/ sternal indrawing
Complications of bronchiolitis?
Respiratory and cardiac failure(especially if premature or pre-existing conditions)
What is usually the cause of Bronchiolitis?How is this confirmed?
Respiratory Syncytial VirusBy PCR on throat or perusal swab
Therapy for bronchiolitis?
Supportive
What is metapneumovirus?
A respiratory viral pathogen that causes acute respiratory tract infection in childrenMost children have antibody by age 5
What diseases does metapneumovirus cause?
Second only to RSV in bronchiolitis2% of cases pf influenza-like illness Ranges in severity from mild to requiring ventilation
How is metapneumovirus confirmed in the lab?
PCR
what is a cause of infantile pneumonia related to an STI?How is it diagnosed?
Chlamydia trachomatisPCR on urine of mother or perusal/ throat swabs of child
What does chlamoydophila pneumonias cause?
Mostly mild respiratory infecitonPerson to person spread
What is the upper respiratory tract colonised with?
Gram positives:Alpha-haemolytic streptococci inc. strep pneumoniaeB-haemolytic streptococci inc. strep pyogenesStaph aureusGram negatives:Haemophilus influenzaeMoraxella catharalisMany others
What are the 5 types of upper respiratory tract infections
SinusitisRhinitisPharyngitis (includes pharynx, tonsils and uvula)EpiglottitisLaryngitis
What usually causes epiglottitis/
Haemophilus influenzae type B
Clinical picture of epiglottitis?
Children (2-7):Acute onset (hours)Sore throatDroolingsevre croup/ stridorHigh tempAdult onset is days
How do we test for epiglottitis?
Blood culture
Why do we not test for epiglottis using a throat swab?
It can irritate the epiglottis further causing it to swell up further
Treatment for epiglottis?
Usually admitted to ICU and treated with Ceftriaxone
Are the conducting airways (trachea and bronchi) usually colonised?
No
When do patients tends to get infection in their conducting airways (trachea and bronchi)?
Changes to airway e.g. trauma/ intubationAirway abnormalitiesVirulent pathogen
What are the pathogenic causes of acute COPD exacerbation?
Can be environmentalHaemophilus influenzaeMoraxella catarrhalisStreptococcus pneumoniaeGram negativesVirus
Why do patients with CF tend to get frequent infections?
Inefficient clearance and build-up of mucus
What types of bacteria are often seen in CF patients?
Staph aureus. haemophilus influenzae, strep pneumoniae, pseudomonas aeruginosa, Burkholderia cepacia and MANY others
What is whooping cough (pertussis)?
Acute tracheobronchitis
What are the clinical features of whopping cough (pertussis)
Cold like symptoms for 2 weeksParoxysmal coughingRepeated voilent exhalations with severe inspiratory whoop, vomiting commonResidual cough for month or more
What bacteria causes whooping cough?
Bordetella pertussis (gram negative coccobacillus)
How is pertussis diagnosed?
Bacterial culture (pernasal swab)PCR (pernasal swab)Serology
Treatment of pertussis?
Antibiotics if had cough for less than 21 days - clarithromycin (erythromycin if pregnant)
Clinical features of CAP?
CoughIncreased sputumChest painDyspnoeaFeverCXR with infiltratesAcquired in the community
Is legionella gram negative or gram positive?
Gram negative
Clinical features of legionella pneumonia?
Flu like illness which may progress to severe pneumonia, with mental confusion, acute renal failure and GI symptoms
How is legionella pneumonia spread?
No person to person spreadInhalation of contaminated water dropletsTherefore associated with shower heads, cooling towers, air conditioning
Diagnosis of legionella pneumonia?
Legionella urinary antigen (detects serogroup 1 only)PCR available direct from sputum
Treatment of legionella pneumonia?
Clarythromycin, erythromycin, levofloxacin
What is the greatest risk for developing hospital acquired pneumonia?
Endotracheal intubation with mechanical ventilation (also risks with sedation, micro aspirations, aspirations of GI contents, immunosuppression)
Microbiology of HAP?
60% = gram negative including E. coli, Klebsiella spp, pseudomonas app, CAP organisms, S aureus and anaerobes
Treatment of a severe HAP?
IV amoxicillin, metronidazole and gentamicinStep down to PO co-trimoxazole + metronidazole
Treatment of non-severe HAP?
PO amoxicillin + metronidazole
What is the full name of PCP?
Pneumocystis jirovecii pneumonia
What type of patients get this?
One of the most frequent and severe opportunistic infection in people with weakened immune systems e.g. aIDS, immunosuppression (people with a normal immune system can be asymptomatic with it either carrying it or eradication it)
What type of organism is pneumocystitis jirovecii?
Fungus
Does mycoplasma pneumonia cause a dry or wet cough?
Dry
Symptoms of PCP?
FeverDry coughSOBFatigueHIV patients = sub-acute, low grade fever, severe pneumoniaNon-HIV = more acute high fever
Diagnosis of PCP?
Microscopy (immunofluorescence of gargle)PCR
Treatment of PCP?
Co-trimoxazole or pentamdine
What are a list of causes of CAP?
Streptococcus pneumonia (Common)Haemophilus pneumoniae (common)Moraxella catarrhalis (common)Mycoplasma pneumonie (common, atypical)Chlamydias (pneumoniae (atypical), psiticci (atypical), trachomatis)PCPLegionella pneumoniae (atypical)Staphylococcus aureusCoxiella burnetti (atypical)Viruses
Aside from PCP, what is another fungal chest infection?
Apergillus
What causes aspergilus chest infection?
Usually aspergillum fumigates (common environmental fungus)
What type of patients get aspergillus chest infection?
Immunocompromised/ supressed patients(causes severe pneumonia and invasive disease)
What type of infection do immunocompetent patients infected by aspergillus get?
Localised pulmonary infectionAspergilloma (fungus ball) in pre-existing chest caivties
How is aspergillus diagnosed?
Bronchoalveolar lavage ideally (fungal culture, PCR)Tissue (histopathology)
Treatment of aspergillus?
Amphotericin BVoriconazoleSurgery
Causes of TB?Appearance of TB?
Mycobacterium tuberculosisAcid alcohol fast bacilli with a thick waxy coat
Pathogensis of TB?
Mycobacterium tuberculosis are engulfed by alveolar macrophages in alveoli but resist killing and multiply leading to a focus
Types of TB?
90% asymptomatic and develop latent TB (alterations in immune function leads to reactivation and active TB)10% develop immediate active TB
Clinical symptoms of TB?
Long term coughChest painSputum =?- haemoptysisWeakness or fatigueFever and chillsNight sweats
Diagnosis of TB?
Microscopy of sputum/ tissueCulture on selective mediaPCRImmune reaction
How is microscopy of mycobacterium tuberculosis prepared?
Ziehl-Neelsen (ZN) stain is used - red dye which is added to smear and heated to allow dye to penetrate waxy coat, acid/alcohol addedWaxy coat of mycobacterium retains the dye even after exposure to acid and alcohol
