Other Gram Negative Rods: (Venketaraman)

* H. influenza

* Bordatella pertussis

* Legionella

* Brucella

* Fracisella tularensis

* Yersinia Pestis

Three Encapsulated Strains Causing Invasive Disease

Pneumococcus

Meningococcus

Haemophilus influenza

H. influenza Characteristics

Type B is most virulent> meningitis and sepsis in children

Non-encapsulated> otitis media and sinusitis

Cultured on chocolate agar with factor V and factor X

H. influenza Epidemiology

Inhale aerosol droplets with microbe

Initially mild or asymptomatic

Use IgA protease to get into respiratory epithelial cells.

Capsulated=invasive

Non capsulated=non invasive. Just URT infection

Peak infection age 6mo-6yrs when mom Abs worn off.

H. influenza Pathogenesis

IgA protease

Polyribosyl Capsule=antiphagocytic

Endotoxin

NO EXOTOXIN

Symptoms for Sinusitis

Otitis media Symptoms

Other serious infections caused by H. Influenza:

(Rarer)

Sepsis

Epiglottitis (life threatening but rare)

Pneumonia with chronic obstructed lung disease in adults.

H. influenza Lab Diagnosis and Treatment

Grown in chocolate agar supplemented with factor V(NAD) and X(heme)

Ceftriaxone treatemtn, penicillin resistant.

Respiratory Tract infection: Amoxicillin-clavulante or trimetheoprim-sulfamethoxazole

Vaccine against capsule

Bordatella Characteristics

Coccobacillary

Encapsulated, gram negative bacteria

Causes whooping cough

Pertussis Pathogenesis

Aerosol droplet transmission, human pathogen

Attach to ciliated cells w HA

Kills cilia and invades upper respriatory epithelial cells

Pertussis Toxin induces mucus production in lungs

B. Pertussis Toxins (LOTS!)

Pertussis: ADP Ribosylates Gi> adenylate cyclase on>cAMP levels up>protein kinase levels up

Protein Kinase: induces mucus production, inhibits signal transduction by chemokine receptors

Adenyl cyclase: taken up by macrophage, inhibits antimic. mechanisms

Cytotoxin + Endotoxin induce NO production which kills ciliated epitheli

Pertussis Clinical Findings

URT

Severe paroxysmal cough for 1-4 wks. Mucus and whoop (in children)

Up to 70% lymphocytes in leukocytosis

Pertussis: Diagnosis, Treatment, Prevention

Cultured on Bordet-Gengou medium

slowly fluorescent antibody stained due to slow growth.

PCR also used

Treat with erythromycin

Two Vaccines: heat killed and acellular

Legionella Characteristics

Atypical pneumonia

Cultured in charcoal-yeast media with iron and cysteine supplement

Legionella Pathogenesis

Water sources like air conditioners and cooling towers, mops, sinks, showers

Inhale bacteria

Cause atypical pneumonia

Severe case--> bacteremia, infect other organs

Endotoxin main virulence, NO EXOTOXIN

Men who smoke and dirnk susceptible

CMI important to fight infection

Legionella Clinical Findings

Vary from mild influenza to severe pneumonia, mental confusion, diarrhea, proteinuria.

Differentiate between this and other microbes causing atypical pneumonia.

Lab Diagnosis: Legionella

Grown in charcoal yeast media with iron and cysteine.

ELISA on urine sample

Sample stained with fluorescent Ab

Legionella: Treatment and Prevention

Erythromycin

Fluoroquinolones more broad, also kill mycoplasma and streptococcus

Prevent aerosoles by water source, drinking, smoking, treat water with chlorine.

Brucella Characteristics

Gram negative bacteria lacking capsules

Cause Brucellosis

Three main human pathogens and animal reserviors:

• B. melitensis-goats and sheep-more virulent
• B. abortus- cattle
• B. suis- pigs

Brucellosis Pathogenesis

*Entrance via direct contact with skin or ingesting contaminated milk or dairy products.

*In reticuloendothelial system: LN, spleen, liver

*Granulomas formed (can progress to caseating)

*Not understood but loss of O antigen=loss of virulence

Brucellosis Clinical Findings

*3 wks incubation>fever, chills, fatigue

*Fever concomitant with enlarged liver, spleen and LN

Brucellosis Diagnosis, Treatment, Prevention

*Agglutination test, serological test

*Treat with rifampicin+tetracycline

*Prevent by pasteurizing milk and destroying infected animals

Fracisella Tularensis Characteristics

* Zoonotic

* Causes tularemia or ulcerglandular disease

* contained dermocenter tick

* Rabbit and deer reserviors

Tick bites human. Bacteria infect reticulo-endothelial system.

Liver spleen and LN enlarge, granuloma and caseation.

Flu-like symptoms:myalgias, headache, fever

Endotoxin, no exotoxin.

No person to person transmission

Streptomyocin

Yersinia Pestis Characteristics

*Safety pin staining, Gram Negative

*Outer polysaccharide capsule and proteins for virulence (acapsular not virulent)

*Plague, black death, zoonotic

* Transmitted by wild rodents with fleas

Sylvatic Cycle

Y. pestis

Enzootic Cycle or Urban Cycle

Y. pestis

Events in the Flea

Yersinia pestis

*Flea bites rodent and ingests bacteria in blood.

*Blood clots in flea gut via bacteria's coagulase production

* Bacteria are able to multiply in coagulated blood

* This blocks alimentary canal of flea and inhibits its feeding.  Ralphs on rodent (or humans)

* In humans, spreads to LN

  Y. pestis Virulence Factors

*Envelope capsular Antigen F-1=antiphagocytic

*Endotoxin=DIC and vascular collapse

*Exotoxin V and W antigens=survive in macrophage

*Yersinia Outer Protein (YOP) inserted in via *Type III secretion, inhibits cytokine signaling, impairs TNF-alpha production.

Y. pestis: Clinical Findings

* Swollen tender LN=bubos

* Pneumonia and septic shock-life threatening events

* Aerosol inhalation or disseminated from LN to lungs.

* 50% fatal without treatment (plague)

Y pestis Treatment, Diagnosis, Prevention

* Strep and tetracycline

* No known drug resistance

* LN smears stained with Giemsa or Wayson for safety pin shape.

* IF stain and Ab titers against capsule Ags

* Isolate for 72h after treatment. Mandatory reporting