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Letter
Rickettsia massiliae
Human Isolation
Giustina Vitale,* Serafino Mansueto,* Jean-Marc Rolain,† and Didier
Raoult†
*Azienda Ospedaliera Universitaria Policlinico "P. Giaccone,"
Palermo, Italy; and †Université de la Méditerranée, Marseille, France
Suggested
citation for this article
To the Editor: The number of new rickettsial species that cause
diseases in humans is rapidly increasing (1).
Moreover, many of the species first described in ticks have been recently
shown to be pathogenic. Of the 10 species or subspecies found to be pathogens
after 1984, a total of 7 were first isolated from ticks (2).
We report the first isolation of Rickettsia massiliae from a patient.
The bacterium was isolated in Sicily in 1985 and identified in 2005.
A 45-year-old man was hospitalized in Palermo, Italy, on June 6, 1985,
for fever and a rash. He had been febrile since May 25 and did not respond
to antimicrobial drug treatment using cefamezin, a first-generation cephalosporin.
On examination, he had a necrotic eschar on his right ankle, a maculopapular
rash on his palms and soles (Appendix Figure
1), and slight hepatomegaly. Leukocyte count was normal; he received
tetracyclines for 13 days and fully recovered. He seroconverted (from
0 to 1:80 between day 11 and day 24) by indirect immunofluorescence to
Rickettsia conorii (R. conorii spot, bioMérieux, Marcy l'Étoile,
France).
Four milliliters of heparinized blood sampled before treatment were inoculated
in a 25-cm2 flask containing Vero cells and incubated at 33°C
in a CO2 incubator (1). Direct immunofluorescence
test on a sample of the patient's serum was positive 7 days later. The
strain was stored for 20 years and tested in 2005 at the Unité des Rickettsies
for identification, and R. massiliae was identified. DNA was extracted
from the cell culture supernatant and used as template in 2 previously
described polymerase chain reaction (PCR) assays that targeted a portion
of the rickettsial ompA gene as well as a portion of the rickettsial
gltA gene (3,4). Amplification products
of the expected size were obtained from this extract but from no concurrently
processed control materials, including 3 negative controls. DNA sequencing
of the positive PCR products gave 100% identity with R. massiliae
for ompA (GenBank accession no. RBU43792) and 99.9% homology for
gltA (GenBank accession no. RSU 59720).
R. massiliae was first isolated from Rhipicephalus ticks
in Marseilles (5). It is transmitted transovarially
in Rhipicephalus turanicus (2). R. massiliae
is commonly found in Rhipicephalus sanguineus or R. turanicus
in France, Greece, Spain (identified as Bar 29) (6),
Portugal, Switzerland, Sicily (D. Raoult, unpub. data), Central Africa,
and Mali (2). R. massiliae may be commonly
associated with these ticks, which are distributed worldwide.
R. massiliae is grouped phylogenically with Rickettsia rhipicephali
and Rickettsia aeschlimannii (Appendix
Figure 2). Bacteria from this group have a natural resistance to rifampin
that is associated with an rpoB sequence that is different from
that of other rickettsiae. This isolate was not tested for antimicrobial
drug susceptibly (7). Rifampin resistance leads
us to believe that this isolate may cause a Mediterranean spotted fever–like
disease that was described in children in Spain (7,8).
Serologic findings were recently reported that showed some patients in
Barcelona, Spain, with reactions that indicate R. massiliae (B29
strain) rather than R. conorii (6). However,
serologic reactions are only presumptive; isolation from a patient is
the required to initially describe a new disease (9).
This Sicilian index case shows that R. massiliae is a human pathogen.
It contraindicates using rifampin to treat Mediterranean spotted fever
in areas where R. massiliae is endemic, as it cannot as yet be
differentiated from R. conorii infection. R. massiliae is
a new example of a strain identified in ticks for several years before
its first isolation from a human patient (10).
The longest delay was observed for Rickettsia parkeri, which was
isolated from ticks in 1939 but not from a patient until 2004. Many authors
labeled R. parkeri a nonpathogenic rickettsia during this time
(1). In the present case, the human isolate was
obtained before the tick isolate but was not further identified. When
this strain was isolated, R. conorii was the sole Rickettsia
sp. found in ticks in southern Europe. Moreover, only 1 tickborne pathogenic
Rickettsia sp. was believed to circulate in a single area. Since
that time, several tickborne rickettsial diseases have been shown to exist
in the same area, which prompted us to retrospectively identify this strain.
The patient was reexamined in May 2005, after this identification. He
is healthy and has no remaining antibodies against Rickettsia spp.
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Suggested citation
for this article:
Vitale G, Mansueto
S, Rolain J-M, Raoult D. Rickettsia massiliae human isolation [letter].
Emerg Infect Dis [serial on the Internet]. 2006 Jan [date cited].
Available from http://www.cdc.gov/ncidod/EID/vol12no01/05-0850.htm
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