Haemophilus, Corynebacterium

Haemophilus, CorynebacteriumBy: Cindy Lou A. TunguiaBSN-II

genusofGram-negative

pleomorphic

coccobacilli,bacteriabelonging to thePasteurellaceaefamily

HaemophilusHaemophilus influenzaeon ablood agarplate.2Haemophiluspathogenicspecies: H. influenzaea cause of sepsis and bacterial meningitis in young childr H. ducreyi _ the causative agent ofchancroid. SerotypesThe unencapsulated strains- are termed nontypable

The encapsulated strains- were classified on the basis of their distinct capsular antigens.

ThepathogenesisofH. influenzaeinfections is a serotype causing conditions such asepiglottitis

The unencapsulated strains - less invasive produce an inflammatory response in humans, which can lead to many symptoms.

Vaccination withHib conjugate vaccineis effective in preventing Hib infectionTwo major categories ofH. influenzae:

DiseasesMost strains ofH. influenzaeare usually live in their host without causing disease cause problems only when other factors (such as a viral infection, reduced immune function or chronically inflamed tissues, e.g. from allergies) create an opportunity. Acquired disease caused byH. influenzaeoccur in humans only:In infants and young children,H. influenzaetype b (Hib) causes bacteremia,pneumonia,epiglottitisand acute bacterialmeningitis.

On occasion, it causescellulitis,osteomyelitis, andinfectious arthritis.

However, Hib remains a major cause of lower respiratory tract infections in infants and children where the vaccine is not widely used.

Diagnosis and treatmentUsing a sample of infected body fluid, such as blood or spinal fluid.

Treated with antibiotics, usually for 10 days. Even with antibiotic treatment, 3%-6% of all children with Hib meningitis die from the disease.

EpidemiologyHaemophilus influenzaecolonizes healthy children and adults

Is spread by direct contact, secretions, and/or aerosol.

Haemophilus ducreyiis spread by venereal contact. There is no animal reservoir for these organisms.

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CORYNEBACTERIUM CorynebacteriumGenusofGram-positive Rod-shapedbacteria.They are widely distributed in nature and are mostly innocuous.Some are useful in industrial settings such asC. glutamicum.Others can cause human disease.C. diphtheriae, for example, is thepathogenresponsible fordiphtheria.CHARACTERISTICSGram-positive

Catalasepositive

Nonspore-forming

Nonmotile

Rod-shaped bacteria that are straight or slightly curved.Also appearelliptical.

They areaerobicor facultatively anaerobic,chemoorganotrophs

With a 5165%genomicG:C content.

Pleomorphicthrough theirlife cyclesCULTURECorynebacteria grow slowly, even on enriched media.

Some strains also needthiamineandPABA.

Corynebacteriumspecies with sequenced genomes have between 2.5 and 3 million base pairs.

The bacteria grow inLoeffler's medium,blood agar, andtrypticase soy agar(TSA).

They form small grayish colonies mostly translucent, but with opaque centers, convex, with continuous borders.

The color tends to be yellowish-white in Loeffler's medium. HABITATOccurs commonly in nature in the soil, water, plants, and food products.

The nondiphtheiroid Corynebacteriumspecies can even be found in themucosaand normalskin floraof humans and animals.

Some species are known for their pathogenic effects in humans and other animals.

Perhaps the most notable one isC. diphtheriae, which acquires the capacity to producediphtheria toxinonly after interacting with abacteriophage.Other pathogenic species in humans include:C. amicolatum,C. striatum,C. jeikeium,C. urealyticum, andC. xerosis

All of these are important as pathogens inimmunosuppressedpatients.

Pathogenic species in other animals includeC. bovisandC. renale.