clinically important infections Flashcards
haemophilus infulnzae ( h.infuelza )
epidemology:
* Reservoir: – ,
colonises —
* Incidence (Haemophilus
influenzae b, Hib):
– 3 million episodes of serious
disease globally
– 400,000 deaths/year
* — Disease , 95% of invasive disease caused by —
– —-
(Hib)
Risk factors
* —
* –
*—/—
* congenital or acquired — deficiencies
* e.g., — (CD4 T cell),
complement deficiency
-H. influenzae is NOT
the cause of influenza
humans
nasopharynx
invasive
encapsulated strain
Haemophilus influenzae b
young children
unvaccinated
hyposplenism n asplensim
immunological
hiv
pathogenesis of infection w capsulated h.infuelza:
- gets in by the colonisation of —
- attached to the cell by Fimbriae/Pili
Attachment Outer Membrane Proteins
- invade/defear immune system w capsule which is critical virulence
factor that facilitates — and— dissemination
- causes damaged to the host cell since capsule prevents —- by —-
- inhalation of —- or — with respiratory secretions
oropharynx
invasion n haemotgenous
antibody - complement activation
by endotoxins LPS
respiratory droplets or direct contact
HAEMOPHILUS INFLUENZAE B
(HIB)
* Respiratory tract infections in early childhood as:
– —-
– —-
* —-
– Untreated mortality as high as –
– Sequelae: — , – , and — impairment
* —
– Often with: – , — , –
acute epiglottis
pneumonia
meningitis
90%
deafness seizures and intracellular impairment
septicaemia
Meningitis, Septic arthritis, Cellulitis
infection w non-capsulated h infleuzea:
* Commonly colonise pts with —
disease
– — is damaged by air pollutants,
smoking
* Preceding or coincident – infection may also precipitate infection
▪ Sinusitis (recurrent)
▪ Acute/chronic bronchitis
▪ Acute & chronic otitis
media
▪ CAP
▪ Less commonly from –
chronic pulmonary disease
ciliated columnar epithelium
viral
invasive infection
haemophilus spp feature:
* Pleomorphic — /—
* Stain –
* Facultatively —
– Maximal growth in 5% —
* –
– Special — requirements for
growth
– Found in – agar
lab diagnosis:
1- systemic infection:
Epiglottitis, BSI, cellulitis, septic arthritis
– — cultures
– — fluid (septic arthritis)
– — for culture & — susceptibility where. appropriate
* N.B. Extreme caution with — & – or – swabs:
– Potentially –
– May precipitate complete airway –
– Contraindicated
Suspected meningitis
▪ – for culture & –
▪ — for microscopy , culture & PCR
GNB / coccobacili
fainly
anaerobic
co2
fastidious
nutritional
chocolate
blood
joint
swab n antibiotic
children ,laryngeal , and epiglottic swabs
dangerous
obstruction
blood
pcr
CSF
1- antibiotic treatment:
* Depends on —/—of infection and guided by — testing results (when available)
* — antibiotics = — of treatment.
– However ~ 20% of isolates are — producers
– — increasing resistance (varies by region)
* In-patient treatment:
– Intravenous (IV) co-amoxiclav ( — infection)
– IV cefotaxime/ceftriaxone (— ,—)
* Out-patient treatment:
– oral—
– – (e.g., clarithromycin)
2- prevention of HIB disease:
* 0000
– Purified capsular polysaccharide conjugated with protein carrier
– Included in many routine childhood immunisation
programmes
* Ireland: 2, 4, & 6 months with a booster at 13 months
* There is NO vaccine in general use for — strains
* Cause a considerable burden of disease BUT they are not major primary pathogens
* However the incidence of invasive infection with these organisms is increasing
* Several vaccine candidates are under investigation
site and severity
suspetibitliyy
b lactam = corerstone
b lactamase
amoxilin
respiratory
bsi and mengitis
co-amoxiclav
macolids
vaccines
non encapsulated
bordetella pertussis - whooping cough:
* – contagious infection of the — tract
* Occurs at — age
– Most severe in — ; mortality rates estimated at 4%
* — disease – always inform public health
* — worldwide
– >45 million cases occur annually with 250,000 deaths
– 30% of adults with a cough lasting >2 weeks may have
pertussis
* Prior to the introduction of immunization, epidemics occurred every 4-5 years, with the highest attack rate in —
highly
respiratory
any age
infant
notifiable
endemic
young children
pertussis resurgence:
* Many countries have recently experienced problems with increased numbers of cases including deaths
– Reduced herd — – lack of natural – and waning –
– — term protective efficacy of acellular pertussis vaccines
– — can occur
– Improved — diagnosis
– An additional – is now recommended for:
* children aged —
* — workers
* —
pathogenesis:
- gets in by inhalation of —
- attaches to the cell by :
Filamentous haemagglutinin ( — cells)
Pertactin ( – cells)
Fimbriae ( – cells)
- defeat n invade by — but w unclear role
- causes damage by —-
- get out through shed in — w — or –
immunity
boosting and waning immunity
poor long
reinfection
laboratory
booster
11-14
healthcare workers
pregooo
droplets
militated , tracheal , ciliated
capsule
cytotoxin , pertussis toxin , endotoxin LPS
shed in repistaoty droplets w coughing or snzeenzing
stages of whooping cough:
1-Catarrhal Stage (– weeks)
– — symptoms e.g., generalised malaise, rhinorrhoea, and mild cough
– The – infectious stage
2- Paroxysmal Stage (– weeks)
– Paroxysmal cough: severe, vigorous coughs that occur during a single expiration following by vigorous inspiration ( — sound)
– Post-tussive —
3- Convalescent Stage (— weeks)
– Gradual — in the — and – of cough
* Total duration of all three phases —
1-2 weeks
nonspecific
most
1-6
whooping sound
vomit
3-4
reduction
frequency ad seevrity
~3/12
chrck slide 22
1- pertussis complication:
hospitalization rates estimated at 9.9% (CDC)
* Infants (<1 year) make up significant proportion of
hospitalization (49.9%)
Complications in infants hospitalized:
* — = 20%
* — = 3%
* — = 0.3%
* – = 50%
* – = 1-4%
2- diagnosis:
* Clinical features
* Microbiological tests
– Nucleic Acid Amplification tests (NAAT) – PCR – more sensitive than — and –
– Culture:
* Aspiration of nasopharyngeal secretions (in the very young) OR
* Nasopharyngeal swab – special transport medium – rapid
transport to laboratory
– Serology: may be affected if recent –
* Other supportive lab tests
– ↑ WCC with predominant —
* — organism
– — agar, may take up to – to grow
– Gram – — (tiny)
- Pneumonia = 20%
- Seizures = 3%
- Encephalopathy = 0.3%
- Apnoea = 50%
- Death = 1-4%
more sensitive and faster
vaccines
lymphocytosis
fastidious
Charcoal-blood
10 days
-ve
coccobacili
1- treatment of whooping cough:
* Primarily supportive
* — (e.g., Azithromycin/clarithromycin)
– If given in catharral stage then can improve – course (disease rarely recognized at this stage)
– Given within – of cough onset to reduce onward transmission
– — not indicated beyond this stage
– Discuss with Infectious diseases/Microbiologist to ensure
treatment indicated/appropriate agent given
* Hospitalisation & ICU care may be required in the –
* Inform – health!
2- prevention:
* — infant immunisation is recommended
* Whole cell pertussis vaccines were used in the past
– Suspension of killed organisms
* — vaccines are now generally used
– Contains — (proteins)
– Significantly fewer local/systemic reactions than observed with whole cell vaccine
– Administered in – with Diphtheria, Tetanus and acellular Pertusis vaccines (DTaP, “ – Vaccine”)
– Ireland: 3 doses (2, 4, 6 months), boosters (4-5 years and adolescence)
macrolide
clinical
14 days
antibiotic
very young
public
universal
acellualr
antigens
combo
triple
legionella species:
* Family Legionellaceae
– – species
– >– serogroups
* Legionella pneumophila causes 85% of – infections with the species
– L. pneumophila serogroup – is responsible for most (90%) infections
* Gram — bacillus
– —
– —
– Strict –
50
70
human
1
-ve
flagella
non capsulated
strict aerobes
L.penumophilia epidemiology:
* — / – disease
– Account for 2 – 9% of cases of CAP
– 10,000-20,000 cases/yr in USA vs ~10/yr in Ireland
* – organisms
– Natural habitats are – bodies
– Colonisation is enhanced by – temperatures (25- 42oC), water stagnation, scale and sediment
* Isolated from water, air-conditioning units, shower heads, piped water supplies & taps, in hotels,
hospitals, spas, cooling towers
– Infection arises following inhalation of – from contaminated water
- clinical features:
* Patient characteristics
– Male: female ratio of —
– Typically aged – years; uncommon < – years
* Clinical manifestations
– Pontiac fever ( – patients): brief flu-like illness, and is —
– – (Often under recognized)
* Risk factors for severe disease:
– –
– –
– –
sporadic /endemic
ubiquitous
aquatic
warm temp
aerosols
– Male: female ratio of 2:1
– Typically aged 50-60 years; uncommon <30 years
younger patients
self-limiting
CAP
* Risk factors for severe disease:
– Old age
– Cigarette smoking
– Immunosuppressio
legionnaires disease - clinical course:
* Incubation period is —
* Abrupt onset of fever, chills, dry cough, headache
* May get – disease of GIT, CNS, Liver
* Renal involvement results in proteinuria, haematuria & — (due to renal tubular acidosis)
* Overall mortality of 15-20%
– Higher in patients with severely depressed cell-mediated immunity ( – recipients) or if treatment
is –
2-10 days
multi organ
hyponatraemia
transplant
delayed
how to confirm diagnosis:
1- — detection
* The most commonly used test
* Sensitivity serotype –:
– 60-90%
– Does NOT detect other – /–
*— test
2- diagnosis is by:
* Done via:
– –
– — aspirate
– —
* If you suspect LD – you need to tell the –
* Culture requires specific — media
– E.g., — extract (BCYE) agar & – to which the organism is resistant to inhibit growth of other bacteria
* Colonies appear after – days incubation
3- treatment and prevention:
— agents are not effective
* Drugs with good — penetration are required
* Examples of agents used:
– Respiratory — , e.g., levofloxacin
– — , e.g., azithromycin or clarithromycin
* Prevention: (Attention to plumbing)
– Keep the hot water hot (>500C) & cold water cold (<200C)
– Avoid areas of water stagnation: ‘dead legs’, unused
outlets
– Programme of flushing taps and showers
urinary antigen
1
stereotypes/species
rapid test
sputum
tracheal
BAL
microbiologist
growth
buffered charcoal yeast
antibiotic
2-3 days
b lactams
intracellualr
flurioquiolones
macrolide
