Notes
Pertussis, Legionnaires, and Related Viruses
Sections
Misc. Gram-negative Rods
Pertussis, Legionnaires, and Related Viruses
Bartonella
Transmitted to humans via insect vectors.
Bartonella bacilliformis
Causes Carrión disease, primarily in the Andes mountains.
Oroya fever: 1st phase of infection
– Acute hemolytic bacteremia with fever and anemia.
– Can be fatal.
Chronic verruga peruana (Peruvian warts): 2nd phase
– Blood-filled cutaneous nodules.
Treat with chloramphenicol or ciprofloxacin.
Bartonella quintana
Transmitted in louse feces;
Trench fever, which is also referred to as "5-day fever" because of recurring fever with headache, weakness, and pain in the long bones, particularly the tibia.
Bacteremia: Immunocompromised individuals can develop bacteremia with myalgia, malaise, weight loss, fever, and headache.
Bacteremia can lead to subacute endocarditis or bacillary angiomatosis, which is characterized by neovascular proliferation and formation of blood-filled nodules in the skin, subcutaneous tissues, and bones.
Bartonella hensela
Transmitted by cats and their fleas.
Cat-scratch disease typically presents as lymphadenopathy; however, infection can become disseminated.
Bacillary angiomatosis of the skin, lymph nodes, spleen, and liver.
Subacute endocarditis
Bordetella
Causes pertussis, aka, whooping cough.
Childhood vaccine DTaP (Diphtheria, Tetanus, and Pertussis) and "booster" vaccines prevent pertussis.
Bordetella pertussis and Bordetella parapertussis; Bordetella pertussis causes the more severe form of illnesss.
Pertussis is most severe in infants, in whom it can lead to respiratory failure.
Cases of adolescent and adult pertussis are on the rise; these populations are reservoirs for the bacteria.
Stages of Pertussis
– 7-10-day incubation period
– Catarrhal stage: 1-2 weeks of symptoms that resemble the common cold.
– Paroxysmal stage: 1-10 weeks of forceful coughing fits followed by inspiratory gasps – the "whooping" sound. Post-tussive vomiting is common.
– Convalescence stage: Coughing is reduced, but serious complications may occur. Pertussis is associated with the development of pneumonia, seizures, apnea, and encephalopathy.
Virulence factors of Bordetella pertussis
Facilitate invasion and destruction of the respiratory tract.
Adhesins, including filamentous hemagglutinin and fimbriae.
Adenylate cyclase toxin blocks phagocytosis and prevents T-cell activation.
Dermonecrotic toxin forms necrotic lesions in the tissues.
Tracheal cytotoxin destroys ciliated cells of the respiratory tract.
Pertussis toxin increases cyclic AMP, promotes leukocytosis, and suppresses the host immune response
– Secreted via Type IV secretion systems.
Brucella
The number one cause of bacterial zoonotic infections worldwide.
Brucella bacteria are associated with livestock; epidemics among farm animals lead to economic devastation.
Brucella melitensis, Brucella abortus and Brucella suis
Brucella melitensis is associated with most human infections.
Intracellular pathogens that cause chronic infections with granuloma formation, particularly in the reticuloendothelial system.
Treatment includes doxycline and streptomycin or rifampin; relapse is common.
Brucellosis mimics other infectious diseases; because of this, diagnosis is often delayed.
Brucellosis
Early infection is characterized by undulant fever with chills, sweating, coughing, vomiting, and weakness.
Advanced infection is systemic with multi-organ effects and increased risk of abortion.
Francisella tularensis
Associated with rabbits, ticks, and flies.
Intracellular pathogen.
Tularensis
Ulceroglandular tularemia is most common manifestation.
– Characterized by localized ulcers and glandular swellings.
Glandular tularemia produces glandular swellings.
Oculoglandular tularemia
Oropharyngeal infections
Pneumonic tularemia can be fatal.
Treatment is gentamicin.
Legionella pneumonia
Found in water, including natural bodies of water, spas, air conditioners, and water misters.
Legionnaires disease
Severe pneumonia with consolidation, as well as multi-organ damage.
Treatment involves Macrolides
Pontaic fever
Less severe than Legionnaires disease
Fu-like symptoms, including fever, chills, myalgia, malaise, and headache.
Antibiotic treatment is unnecessary in most cases, because the illness is self-limiting.
References:
Murray, P. R., Rosenthal, K. S., & Pfaller, M. A. Medical microbiology. Philadelphia: Elsevier/Saunders. (2013).
Levinson, W. E. Review of Medical Microbiology and Immunology. 14th Ed. Lange (2016).
Albayrak, A. & Albayrak, F. (2011). Hepatic granulomas associated with brucellosis. Hepat Mon 11(1):1-2.
Dean, A.S., Crump, L., Greter, H., Hattendorf, J., Schelling, E., Zinsstag, J. (2012). Clinical manifestations of human brucellosis: a systematic review and meta-analysis. PLoS Negl Trop Dis 6(12): e1929. doi:10.1371/journal.pntd.0001929
Castano, M.J. & Solera J. (2009). Chronic brucellosis and persistence of Bruella melitensis DNA. Journal of Clinical Microbiology 47(7): 2084-2089.