Other Pathogenic Gram-Negative Rods 20 Other Pathogenic Gram-Negative Rods

Other Pathogenic Gram Negative Rods The Pasteurellaceae Most are small, nonmotile, facultative anaerobes Require heme or cytochromes for growth Two genera contain most human pathogens of this family Pasteurella Haemophilus

Pasteurella multocida Normal microbiota of oral and nasopharyx of domestic cats and dogs Human infection via animal bites Causes localized swelling of lymph nodes Treat with antibiotics

Bartonella Bartonella henselae Cat-scratch disease Transmitted through cat scratches and bites Causes fever, malaise, and swelling at infection site Bartonella infections are treated with various antimicrobials

Haemophilus influenzae Most strains have capsule that resists phagocytosis H. influenzae type b is most significant strain Common cause of meningitis prior to vaccination Hib vaccine has eliminated most disease by H. influenzae in the United States Other H. influenzae strains cause a variety of diseases Conjunctivitis, sinusitis, dental abscesses, meningitis Figure 20.19 http://youtu.be/ogqrgd3i_mQ

Bordetella pertussis Small, aerobic, nonmotile coccobacillus Disease: Pertussis (whooping cough) Most cases of disease are in children Virulence factors Adhesins and toxins mediate the disease Pertussis toxin Adenylate cyclase toxin Dermonecrotic toxin Tracheal cytotoxin

Bordetella pertussis Transmission Symptoms http://youtu.be/RogpNWYeSQs Bacteria inhaled in aerosols Multiply in epithelial cells Symptoms Occurs in four stages Severe “Whooping” cough symptoms http://youtu.be/wuvn-vp5InE http://www.emedicinehealth.com/slideshow_whooping_cough_pertussis/article_em.htm

Progression of Pertussis Figure 20.25

Bordetella pertussis Treatment Prevention Primarily supportive; Antibiotics decrease number of bacteria but course of disease usually unaffected Tracheal cells need time to regenerate Prevention http://www.mcir.org/forms/Compare_DTaP_Td_Tdap.pdf DTaP at 6 weeks through 6 years Tdap at 10 years through 64 years Td after 7 years old at 10 years intervals http://www.emedicinehealth.com/slideshow_whooping_cough_pertussis/article_em.htm

Legionella pneumophila Description http://www.cdc.gov/legionella/about/ Gram negative intracellular parasites found in water sources survives inside amoeba Pathogenicity resistant to phagocytosis immunocomprommised host Transmission http://youtu.be/fczGdXZBGKo Inhale bacteria in aerosols from water sources not transmitted from human to human

Legionella pneumophila Symptoms: Legionnaire’s Disease 2 -14 days after exposure high fever, dry cough, little sputum, SOB Diagnosis: chest X ray culturing bacteria Treatment: Erythromycin Chlorine and heat (water sources) http://www.cdc.gov/healthywater/pdf/swimming/resources/legionella-factsheet.pdf

Pseudomonas aeruginosa http://youtu.be/3WEMcgQFi5A Description Ubiquitous in soil, decaying organic matter, moist environments Rarely part of normal human microbiota Virulence factors Fimbriae, adhesins, capsule, toxins, and enzymes Despite producing various virulence factors rarely causes disease

Pseudomonas aeruginosa Opportunistic infections Can colonize almost any organ or system Common in the lungs of cystic fibrosis patients Biofilm protects bacteria from phagocytosis Common in burn patients

Pseudomonas aeruginosa Treatment Fluoroquinolones, some aminoglycosides and beta-lactams; usually combination Multiple drug resistance ability to metabolize drugs form biofilms cell membrame pumps Prevention http://www.cdc.gov/hai/organisms/pseudomonas.html

Acinetobacter baumannii http://www.cdc.gov/hai/organisms/pseudomonas.html Description Commonly found in soil and water Very low risk of infection in healthy people May “colonize” a patient without causing infection especially in tracheostomy sites or open wounds Acinetobacter infections rarely occur outside of healthcare settings.

Acinetobacter baumannii Transmission Acinetobacter can be spread to susceptible persons by person-to-person contact or contact with contaminated surfaces Outbreaks occur in hospitalized patients who have weakened immune systems, especially very ill patients on a ventilator, chronic lung disease, open wounds and those with a prolonged hospital stay

Routes of Transmission

Acinetobacter baumannii Diseases Causes a variety of diseases, ranging from pneumonia to serious blood or wound infections, and the symptoms vary depending on the disease.  Acinetobacter infection can either cause or contribute to death in these patients. http://youtu.be/diLrELQ8iEs?t=1m51s

Acinetobacter baumannii Treatment Multidrug resistant; CDC statistics from Iraqi War: 35% of isolates were only susceptible to Imipenem 4% were resistant to ALL DRUGS Prevention Careful attention to infection control procedures, such as hand hygiene and environmental cleaning, can reduce the risk of transmission