Haemophilus, Brucella and Bordetella

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Haemophilus, Brucella and Bordetella
Dr. Brian OConnell
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Parvobacteria
Haemophilus influenzae Invasive disease - meningitis, bacteraemia, osteomyelitis Non-invasive disease respiratory tract.
Bordetella pertussis Whooping Cough
Brucella spp. Brucellosis
Yersinia spp. Diarrhoea and systemic disease
Pasteurella Wound infection after dog/cat bites
Francisella Tularaemia
Legionella Pneumonia
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Parvobacteria
Gram stain of Haemophilus influenzae
Gram stain of E. coli
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H. influenzae

• Small, non-sporing, non-motile bacterium
• Encapsulated strains isolated from cerebrospinal
  fluid are gram-negative coccobacilli
• Non encapsulated organisms from sputum are
  pleomorphic
• Requires preformed growth factors that are
  present in blood, specifically
• X factor (i.e., hemin from iron containing
  pigments)
• V factor (NAD or NADP).
• Usually grown on chocolate blood agar

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Gram stain of H. influenzae from a CSF
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Gram stain of H. influenzae from sputum
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• Epidemiology
• Only found in humans
• Normally found in the pharynx (conjunctiva,
  genital tract)
• Spread by airborne droplets or direct contact
  with respiratory secretions
• Both extra and intracellular pathogen

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Virulence and Immunity

• Some strains are encapsulated with
  polyribosylribitolphosphate (PRP)
• Subdivides H. influenzae into groups a-f
• Type B is a major virulence factor
• 95 percent of bloodstream and meningeal
  Haemophilus infections in children are caused by
  type B organisms
• Encapsulated organisms penetrate the epithelium
  of the nasopharynx and invade the blood
  capillaries directly
• Resist phagocytosis and complement-mediated lysis
  in the the nonimmune host

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• The age incidence of H. influenzae meningitis is
  inversely proportional to the titre of
  bactericidal antibody in the blood
• Passively acquired from the mother or actively
  formed
• In children aged 2 months to 3 years, antibody
  levels are minimal

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Relation of the age incidence of bacterial
meningitis caused by Haemophilus influenzae to
bactericidal antibody titres in the blood
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Clinical Manifestations

• Hib
• Bacteraemia
• Meningitis
• No particular features to distinguish HiB
  meningitis from other causes
• May be fulminant but usually presents with
  several days of mild URTI followed by
  deterioration
• Mortality lt5 but neurologic sequelae are common
• Septic arthritis
• Previously common in children lt2 years
• Single weight-bearing joint

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• Epiglottitis
• Acute respiratory obstruction caused by
  cellulitis of supraglottic tissues
• Usually children aged between 2 and 7 but also
  occurs in adults
• Sore throat, fever, pooling of secretions,
  restless, anxious, sitting in characteristic
  position sitting up, tongue sticking out,
  drooling, inspiratory stridor

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Epiglottitis in an adult
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• Cellulitis
• Reddish-blue hue, typically on cheek

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Haemophilus influenzae type b periorbital
cellulitis
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• Non-typable H. influenzae
• Otitis media
• Sinusitis
• Conjunctivitis
• Exacerbations of COPD
• Pneumonia
• Especially in elderly with pre-existing lung
  disease

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Laboratory Diagnosis

• Gram stain
• Pleomorphic gram-negative coccobacilli
• Culture
• Chocolate agar
• Confirm by growth around X and V discs

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Treatment

• Hib
• Third-generation cephalosporin e.g cefotaxime
  until susceptibility confirmed
• Between 5 and 20 of strains produce ?-lactamase
• Non-typable strains
• Amoxycillin, co-amoxyclav

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Prevention

• HiB vaccine introduced in Ireland in 1992
• Scheduled doses at 2, 4 and 6 months
• Uptake gt90
• Still about 40 cases/year
• 6 vaccine failures in 2004 (Fitzgerald et al.
  2005)

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Haemophilus influenzae Type B Disease by Age
Group 1990 to 2000
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Number of invasive H. influenzae type b (Hib)
cases in Ireland, 1987-2003 (Based on reports
received at NDSC up to 28/11/2003)
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Bordetella pertussis

• Gram-negative coccobacillus
• Nutritionally fastidious, normally cultivated on
  medium containing blood
• Primarily a human pathogen
• Other members of the genus Bordetella can cause
  disease in animals
• Causes Pertussis (Whooping cough)
• Serious, highly communicable acute
  tracheobronchitis

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Whooping cough - Epidemiology

• Estimated 285,000 deaths in 2001 worldwide
• 131 cases in Ireland in 2002
• 8296 cases in U.S.
• Previously mainly in children
• Now a number of reports of increasing pertussis
  in adults because of the limited duration of
  protection from pertussis vaccine

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Data from HPSC
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Virulence factors

• Filamentous Hemagglutinin (Fha)
• ability to agglutinate RBCs
• Binds to galactose on sulfated glycolipids (in
  membranes of ciliated cells)
• Antibodies to Fha protect against infection
• Pertussis Toxin (PT)
• may act as an adhesin and toxin
• Two toxin subunits (S2 and S3) mediate adherence
• Anti-Pt-antibody prevents colonization of
  ciliated cells, protects vs infection

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• Adenylate cyclase toxin (ACT)
• Mainly cell-associated, can be released
• activated adenylate cyclase leads to impaired
  white cell function
• Tracheal cytotoxin (TCT)
• Peptidoglycan fragment
• Released by lysis
• Kills ciliated cells
• Stimulates release of IL-1 (produces fever)
• Dermonecrotic toxin (DNT)
• Causes smooth muscle contraction leading to
  ischaemic necrosis

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Pathogenesis
Attachment to respiratory epithelium mediated by
FHA and possibly PT
Ciliostatsis and damage to epithelium mediated by
TCT
Inhibition of phagocytsosis mediated by ACT, PT
AND DNT
Systemaic manifestations probably manifested by PT
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Pertussis (whooping cough)

• Spread by aerosol/direct contact
• Early symptoms - nonspecific- seldom diagnosed
  until paroxysmal stage- most contagious early
• Stages- Incubation period 7-10 days- Catarrhal
  stage
• Symptoms like common cold, lasts 1-2 weeks
• Paroxysmal stage
• dry nonproductive cough, paroxysmal
• excess mucus production, vomiting, convulsions,
  cyanosis, paroxysms separated by inspiratory
  whoop
• Lasts 4-6 weeks

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Children who are too young to be fully
vaccinated and those who have not completed the
primary vaccination series are at highest risk
for severe illness
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Complications

• Pneumonia
• Either caused by B. pertussis or secondary
  bacterial infection
• Bronchiectasis
• Neurological damage
• Seizures in 1.4, encephalopathy 0.2 (seizures
  and mental retardation)
• Raised intrathoracic and intrabdominal pressure
  leading to intracranial bleeds, conjunctival
  haemorrhages, petichiae, pneumothorax, inguinal
  hernia etc.

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Laboratory Diagnosis

• Leucocytosis with absolute lymphocytosis at end
  of catarrhal and beginning of paroxysmal stage
• Culture pernasal swab early in course of
  illness, plate on Bordet-Genou or charcoal medium
• PCR
• Serology

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Management and Prevention

• effect of antimicrobial therapy on the severity
  and duration of the illness is debated but
  erythromycin x 14 days (clarythromycin and
  azithromycin are alternatives) is recommended as
  it may reduce the spread of disease
• Antimicrobial prophylaxis (erythromycin x 14 d)
  should be offered to all family members and other
  close contacts
• There is no evidence of any benefit from
  chemoprophylaxis given more than 21 days from the
  date of onset of the primary case.
• Chemoprophylaxis should be considered if a case
  has a household contact who is at greatest risk
  from pertussis primarily young

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Vaccination

• Whole-cell pertussis vaccination is associated
  with rare serious events such as acute
  encephalopathy, estimated to occur at 0.0-10.5
  per million doses
• 1996 several new acellular pertussis vaccines
  developed
• multicomponent vaccines contain combinations of
  pertussis toxoid, filamentous hemagglutinin,
  pertactin, and the two types of fimbriae
• fewer side effects than the whole cell vaccine

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Brucella species

• Gram-negative coccobacillus
• Facultative intracellular parasites
• Six species
• B. abortus - cattle
• B. suis - pigs
• B. melitensis - goats
• B. canis - dogs
• B. ovis - sheep
• B. neotomae - desert wood rats
• Cause zoonoses worldwide
• B. abortus is still prevalent in cattle in
  Republic and Northern Ireland

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• B. abortus
• Disease in cattle- causes abortion, mammary
  infection (not mastitis)- transmission to humans
  by ingestion (infected milk) or inhalation
  (aborted material)
• Disease in humans- long incubation period
  (weeks, months)- malaise, chills, fever,
  sweats- weakness, myalgia, headache- nervous
  symptoms (psychoneurosis)- difficult to diagnose
  due to vagueness of symptoms

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• B. melitensis
• Primary hosts are sheep and goat
• Disease in goat similar to B. abortus in
  cattle
• Early localization in mammary gland,
  shedding in milk leads to human infection
• Gastroenteritis- Malta/Mediterranean fever
• potential agent of bioterrorism

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Pathogenesis

• Ingestion.
• Most common.
• Inhalation.
• Certain occupations e.g. laboratory workers,
  abbattoir workers.
• Enter the body through skin wounds.
• Slaughterhouses or meat packing plants or for
  veterinarians.
• Invades mucous membranes and transported (free or
  in phagocytes) to lymph nodesenter phagocytic
  cells.
• Spread via circulation to other organsliver,
  spleen, bone marrow, kidney cause granulomas.

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Clinical presentation

• Extremely variable.
• Any system can be affected
• In the acute form (lt8 weeks from illness onset)
• nonspecific and "flu-like," including fever,
  sweats, malaise, anorexia, headache, myalgia, and
  back pain. Lymphadenopathy, splenomegaly
• Chronic (gt1 year from illness onset), may include
  chronic fatigue syndrome-like, depressive
  episodes, and arthritis.

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Laboratory Diagnosis

• B. melitensis blood cultures
• B. abortus
• serology SAT, Coombs
• Four-fold rise in titre

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Treatment

• Tetracycline /- rifampicin for 6 weeks

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Yersinia species

• Y. pestis
• Causes plague bubonic/pneumonic
• Transmitted by flea bite, occasionally from
  aeroslisation
• periodic disease outbreaks in rodent populations,
  hungry infected fleas that have lost their normal
  hosts seek other sources of blood
• Rat-borne epidemics continue to occur in some
  developing countries, particularly in rural
  areas.
• Potential bioterrorist agent

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Yersinae pestis
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Yersinia pestis on blood agar
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Protective clothing worn in 14th century Europe
during the Black Death
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Xenopsylla cheopis - Oriental rat flea
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Clinical features

• Bubonic plague
• enlarged, tender lymph nodes, fever, chills and
  prostration
• Septicemic plague
• fever, chills, prostration, abdominal pain, shock
  and bleeding into skin and other organs
• Pneumonic plague
• fever, chills, cough and difficulty breathing
  rapid shock and death if not treated early
• TREATMENT
• Streptomycin/gentamicin, ciprofloxacin,
  doxycycline

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Plague axillary bubo (CDC Public Health Image
Library No2061)
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Plague inguinal bubo CDC Public Health Image
Library No2044
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Peripheral blood smear of septicaemic plague
showing bipolar staining bacilli
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• Y. pseudotuberculosis
• Y. enterocolitica
• Both can cause abdominal symptoms
• Occurs most often in young children. Fever,
  abdominal pain, and diarrhoea, which is often
  bloody
• May mimic appendicitis
• Eating contaminated food, especially raw or
  undercooked pork
• Outbreaks are described
• Usually self-limited
• Tetracyclines

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Pasteurella multocida

• Cause of animal bite infections
• Present in dog/cat oropharynx
• Treat with penicillin

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Dog and cat bites

• Common
• Nearly all infections are mixed
• Aerobes
• S. aureus, streptococci, Pasteurella etc. and
  anerobes
• Consider tetanus and rabies

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• Debride and irrigate
• Tetanus prophylaxis
• Antimicrobial prophylaxis
• Co-amoxyclav for 5- 7 days
• Especially for
• severe early infections
• late (gt8 h) presentation
• Wounds of face, hand, genitals
• Bone or joint involvement
• Immunosuppressed host

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Francisella tularensis

• Small, fastidious Gram-negative bacillus
• Zoonoses
• Predominantly North America type A
• Potential bioterrorist agent no person-person
  spread
• Transmission
• Bite of an infected arthropod
• Contact with infected animals (small rodents)
• Aerosol
• Clinical
• Mainly ulceroglandular or respiratory

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Tularaemia skin ulcer (from HPA)
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Treatment

• Gentamicin/streptomycin
• Ciprofloxacin
• Doxycycline