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HAEMOPHILUS BORDETELLA. Haemophilus sp. Organism Reservoir Transmission H. influenzae Normal flora of human Person-to-person, droplets; upper resp. tract sometimes endogenous H. ducreyi Not normal flora; only Person-to-person; sexual present during infection contact

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Haemophilus sp.

Organism Reservoir Transmission

H. influenzae Normal flora of human Person-to-person, droplets;

upper resp. tract sometimes endogenous

H. ducreyi Not normal flora; only Person-to-person; sexual

present during infection contact

Other Haemophilus spp. Normal flora of human Spread of endogenous strain

upper resp. tract to non-resp. tract sites; less

common than H. influenzae

Clinical characteristics

H. influenzae

Major virulence factor is polyribitol phosphate capsule

- enhance resistance to phagocytosis

- serologic typing based on antigenic characteristics

- six capsule types: a, b, c, d, e, or f

- type b is the most commonly associated with

serious human infection

- infections are often systemic and life-threatening:

meningitis, epiglottitis, cellulitis with bacteremia,

septic arthritis, and pneumonia

Also produce factors that promote attachment to human

epithelial cells

Clinical characteristics, cont.

H. influenzae

Non-typeable strains do not produce a capsule

- virulence mediated through attachment (pili, etc.)

- infections are typically less serious and more

localized: otitis media, sinusitis, conjuctivitis, and


- pneumonia and bacteremia in adults with underlying

medical conditions

- isolated from patients with cystic fibrosis

Clinical characteristics, cont.

H. ducreyi

Virulence factors also uncertain but probably include

capsule, pili and toxins involved in attachment and

penetration human epithelial cells

Etiologic agent of chanchroid

- genital lesions beginning as tender papules

that progress to painful ulcers with several

satellite lesions

- regional lymphadenitis

- primarily occurs in lower socioeconomic groups

in tropical areas

Clinical characteristics, cont.

H. ducreyi

Chanchroid, cont.

- can be distinguished from syphilitic lesions

that are painless

- presence of genital ulcers increases risk of HIV


Clinical characteristics, cont.

Other Haemophilus spp.

Mainly low virulence, opportunistic pathogens

Cause infections similar to H. influenzae but much

less common

H. aphrophilus is an uncommon cause of brain abscesses

and endocarditis

- H of HACEK; subacute bacterial endocarditis

Laboratory Diagnosis
  • Specimen collection
  • Can be isolated from most clinical specimens
  • - relatively high bacterial load in blood
  • of children with bacteremia
  • Susceptible to drying and temperature extremes
  • For H. ducreyi, specimen should be plated within
  • 10 min. of collection
Laboratory Diagnosis, cont.
  • Direct detection
  • Gram stain: most are small, faintly staining,
  • gram-negative coccobacilli
  • H. ducreyi often described as “school of fish”
  • - mostly seen in lymph node specimens
Laboratory Diagnosis, cont.
  • Direct detection
  • Latex agglutination can be performed on CSF or urine
  • - can be falsely-positive for recent vaccinees
  • - sensitivity is equivalent to Gram stain
Laboratory Diagnosis, cont.
  • Culture
  • Haemophilus require hemin (X factor) and NAD
  • (V factor)
  • Chocolate agar contains both
  • 5% Sheep blood agar only contains hemin
Laboratory Diagnosis, cont.
  • Culture
  • S. aureus produces NAD as a metabolic product
  • - Haemophilus will satellite around colonies
  • of S. aureus when growing on BAP
Laboratory Diagnosis, cont.
  • Culture, cont.
  • Growth conditions:
  • Haemophilus spp.: 35 – 37°C, 5-10% CO2, 3 days
  • H. ducreyi: 33 – 35°C, 5-10% CO2, 7 days
  • - also require supplemented media
  • Colony morphology:
  • Small and translucent
  • Exude a “mouse nest” odor
Laboratory Diagnosis, cont.
  • Identification
  • Growth characterics on solid media
  • Gram stain morphology
  • X and/or V factor requirement
  • Satelliting
  • Porphyrin test
  • Antimicrobial Susceptibility Testing and Therapy
  • Routine testing can be performed using disk diffusion
  • or broth dilution
  • Special supplemented media required
  • Beta-lactamase testing routinely performed
  • Test panel limited because of lack of resistance to
  • later generation cephalosporins
  • Cefotaxime or Ceftriaxone are drugs of choice
  • Vaccine
  • Routine vaccination with protein-polysaccharide
  • conjugated vaccine (Hib)
  • Significant reduction of serious, life-threatening
  • infections in children
  • Recommended starting at 2 months of age
Bordetella sp.

Organism Reservoir Transmission

B. pertussis Not normal flora; only Person-to-person; airborne

present during infection transmission via cough

B. parapertussis Not normal flora; only Person-to-person; airborne

present during infection transmission via cough

B. bronchiseptica Normal flora of animal Exposure to contaminated

upper resp. tract droplets following close

(dogs, cats, rabbits) contact with animals

Clinical characteristics
  • B. pertussis and B. parapertussis
  • - cause URT infections in humans with almost identical
  • symptoms, epidemiology and therapeutic management
  • - Pertussis (whooping cough)
  • - optimal recovery requires special culture media
  • B. bronchiseptica
  • - opportunistic infection in compromised patients with
  • history of close animal contact (pneumonia, bacteremia,
  • UTI, meningitis, endocarditis)
Clinical characteristics, cont.
  • Epidemiology
  • Pertussis primarily caused by B. pertussis, rarely by
  • B. parapertussis; former cause more severe disease
  • - higher infection rates and increased duration
  • of symptoms
  • Prior to vaccine, epidemic disease occurred in 2 – 5
  • cycles; still occurs in unvaccinated populations
  • Adults and adolescents can serve as reservoirs and
  • transmit to unvaccinated or vaccinated with waning
  • immunity
Clinical characteristics, cont.


Multiple virulence factors with various functions

Adhesion Fimbriae

Filamentous hemagglutinin

Toxicity Pertussis toxin

Adenylate cyclase toxin

Tracheal cytotoxin

Outer membrane inhibits host lysozyme

Siderophore production to circumvent host iron sequestering

Clinical characteristics, cont.

Spectrum of disease

Catarrhal Mild cold Several weeks

Paroxysmal Severe coughing 1 to 4 weeks


Convalescent  Symptoms Months

Symptoms in adults tend to be milder and are misdiagnosed

as bronchitis; also tend to be mixed with other pathogens

Laboratory Diagnosis
  • Specimen collection
  • Nasopharyngeal wash or swab (Calcium alginate or
  • dacron on a flexible wire shaft)
  • Swabs should be immediately inoculated onto media
  • and direct smears made at the bedside
  • Swabs not directly inoculated should be placed in
  • transport if time to lab is extended
Laboratory Diagnosis, cont.
  • Direct detection
  • DFA of smear using polyclonal Abs against B. pertussis
  • and B. parapertussis
  • Sensitivity is limited (50 – 70% at best), so should always
  • be used in conjunction with culture
  • PCR methods (home-brew and commercial assays) are
  • increasing in use and are replacing culture as gold standard
  • - specificity has been an issue
DFA for Bordetella

ASM Color Atlas of Bacteriology

Laboratory Diagnosis, cont.
  • Culture
  • Historical gold standard
  • Selective media required
  • Bordet-Gengou
  • - Potato infusion agar with glycerol and sheep blood
  • Methicillin or cephalexin
  • Regan-Lowe
  • - Charcoal agar with 10% horse blood
  • Cephalexin
Laboratory Diagnosis, cont.
  • Culture, cont.
  • 35 – 37°C, 5 – 10% CO2, hold for 10 – 12 days
  • - most isolates are detected in 3 – 5 days
  • Colonies are small, shiny; resemble mercury drops
  • Gram stain shows small, faintly staining gram negative
  • coccobacilli
  • - confirm identity with DFA reagents
  • - can distinguish between B. pertussis and
  • B. parapertussis
B. pertussis on Regan-Lowe agar

ASM Color Atlas of Bacteriology

Gram stain of B. pertussis


w/ antibiotics


w/o antibiotics

ASM Color Atlas of Bacteriology

  • Antimicrobial Susceptibility Testing and Therapy
  • Not routinely performed because Erythromycin and
  • Azithromycin are active and remain drugs of choice
  • Vaccine
  • Whole-cell vaccines have been used historically
  • - adverse reactions and waning immunity
  • Acellular vaccines have been developed and include
  • booster doses for older children and adults
neisseria and moraxella
Neisseria and Moraxella
  • General characteristics
    • Gram-negative diplococci, oxidase-positive
  • Epidemiology
    • Table 45-1
  • Pathogenesis
    • Table 45-2
      • Other Neisseria are saprophytes
Gram stain of Moraxella

Laboratory Diagnosis
    • Specimen collection and transport
      • No special considerations for Moraxella
      • Pathogenic Neisseria are sensitive to drying and temp extremes
      • Swabs are acceptable for GC culture if plated in 6 hrs.
        • best method for GC culture is direct inoculation
        • Describe JEMBEC plates
      • Blood cultures as per routine, although Neisseria inhibited by high conc of SPS
    • Specimen processing
      • JEMBEC should be incubated as soon as received in lab
      • Body fluids should be kept at RT or 37C before culture (not cold)
      • Vol >1 ml should be concentrated and plate the sediment (e.g. joint fluid or CSF)
Laboratory detection
    • Direct detection
      • Gram stain
        • shows GN diplococci for both genera; Moraxella tend to be bigger and fatter
        • GNDCs in PMNs from the urethral discharge of symptomatic male is diagnostic for GC
        • Normal vaginal and rectal flora has GNDCs so diagnosis requires confirmation
      • Antigen detection
        • not recommended; poor sensitivity
      • Molecular detection
        • Amplified methods are more sensitive than non-amplified methods
        • Increased detection of GC overall
        • Can test for CT at the same time
        • Cannot be used as evidence in medico-legal cases
        • We use B-D Viper automated instrument
Laboratory detection
    • Culture
      • Media of choice
        • N. meningitidis, Moraxella and saprophytic Neisseria grow well on BAP, CAP
        • GC requires enriched CAP on primary culture
        • Selective media have been developed to inhibit normal flora and allow N. meningitidis and GC to grow
        • Modified Thayer-Martin
        • IsoVitaleX, colistin, nystatin, vanco, trimethoprim
        • Martin Lewis is similar
      • Incubation conditions and duration
        • 35-37C, 3 - 7% CO2, humid, 72 hrs
        • this CO2 conc can be achieved in incubator or candle jar
      • Colony appearance
Culture of Neisseria

Culture of Moraxella

Laboratory detection
    • Approach to identification
      • Biochemicals
        • Moraxella: glucose -, maltose -, lactose -, butyrate disk +, ox +
        • GC: g +, m -, l –, ox +
        • NM: g +, m +, l –, ox +
        • Saprophytes: + + + or any other combo
        • Culture confirm and ID must be unequivocal in abuse cases
        • Saprophytes are not routinely identified (i.e. from respiratory cultures
      • Serotyping
        • Mening: A, B, C, Y, W135
Susceptibility testing and therapy
    • Moraxella
      • testing not routinely performed because many options available
        • beta-lactams; b-l/b-lactamase inhib; cephs; macrolides; quinolones; bactrim
    • GC
      • routinely not performed because most labs use molecular so no isolate
      • resistance is a Public Health issue so surveillance mechanisms exist
        • penicillin resistance is widespread
        • ceftriaxone resistance not documented
        • quinolone resistance is emerging problem
    • N. meningitidis
      • not routinely performed; resistance rare
      • pen, cephs
    • Vaccine available for A, C, Y, W135
      • military recruits, college students, asplenics > 2 y.o.
    • Chemoprophylaxis with rifampin, cipro, or ceftriaxone for close contacts of patients with meningococcal disease
      • no chemo prophylaxis for pneumococcal mening
    • Eye antibiotics for neonates to prevent gonococcal eye infections