31 July = 2008

31 July=20 2008

=93Fx2=94 = Francisella=20 tularensis infection

Of = historical=20 interest, two patients with a microbiologically atypical Francisella tularensis = infection, one=20 designated =93Fx1=94 and the other =93Fx2=94, were reported in 1996 = (Clarridge JE et al.=20 Characterization of two unusual clinically significant Francisella = strains. J=20 Clinical Microbiology 1996; 34: 1995-2000). The preceding newsletter = described the=20 patient with =93Fx1=94, while this one will briefly summarize the = clinical course of=20 the patient with =93Fx2=94 infection.

The patient = was a 43=20 year-old man who was admitted to the hospital in 1995 with a one week = clinical=20 history of fever, shortness of breath, and occasional vomiting and = diarrhea.=20 Over the previous 6 months, he had an unidentified illness that caused a = 45-pound weight loss. He had evidence of left-sided pneumonia on = physical exam=20 and chest X-ray. His labs revealed pancytopenia (decreased white cells, = red=20 cells, and platelets).

Blood = cultures on=20 admission grew the Fx2 Francisella species. He was treated with 2 weeks of = ampicillin-sulbactam for the diagnosis of pneumonia and bacteremia. The fever resolved and the = blood=20 cultures became negative. A bone marrow aspirate and biopsy showed no = evidence=20 of granulomas or cancer (or iron stores). Moderate hepatosplenomegaly = lead to a=20 liver biopsy that did show granulomas, lymphohistiocytic infiltration = and=20 abundant plasma cells. = Special=20 =93stains and cultures=94 of the liver and bone marrow tissue however, = were=20 negative. Serology (acute and convalescent) was negative for = Francisella.

Epidemiologically, the=20 patient had a dog, (but no mention of any ticks). He used well water for = cooking=20 and bathing, but culture of this water did not show any Francisella = bacteria. He=20 lived in a rural area in Liberty County, Texas.

The blood = culture=20 turned positive after 6 days in the aerobic bottle of the Bac-t-Alert = blood=20 culture system. In vitro, it was resistant to the ampicillin-sulbactam = that he=20 was treated with for two weeks. Fx2 was also resistant to ceftriaxone = (unlike=20 Fx1), aztreonam, piperacillin, and erythromycin. It was susceptible to = ciprofloxacin=20 (like Fx1), gentamicin and amikacin. =20 The Vitek NHI microbiologic identification panel suggested that = Fx2 was=20 =93unidentified but possibly Cardiobacterium hominis, Hemophilus=20 Actinomycetemcomitans, or Neisseria subflava=94. The Vitek GNI = identification=20 system suggested Fx2 could be =93Acinetobacter lwoffii=94. =

The patient = is the=20 only one, to my knowledge, ever reported with this Fx2 infection, = subsequently=20 identified as Francisella tularensis novicida (or=20 =93novicida-like=94).

As with the = Fx1=20 Francisella tularensis novicida (like) bacteria described in this same = paper=20 (and summarized on this website earlier this week), the = mis-identification of=20 Fx2 by microbiologic laboratory systems emphasizes the importance of = explicitly=20 performing surveillance for the above named (quite unusual) = non-Francisella=20 bacteria (e.g., Hemophilus. Actinomycetemcomitans (as with Fx1) = Acinetobacter,=20 Cardiobacterium hominus) anytime a possible environmental contamination = is=20 thought to have occurred with Francisella tularensis bacteria that could = include=20 Fx2 (or Fx1).

Daniel R. = Lucey, MD,=20 MPH

EROne = Institutes,=20 Department of Emergency Medicine

Washington = Hospital=20 Center

Adjunct = Professor of=20 Microbiology and Immunology

Georgetown = University=20 Medical Center

Washington,=20 D.C.

Website for = this=20 posting: http://www.bepast.org/

E-mail:=20 DRL23@Georgetown.edu