Host- and microbe-related risk factors for and pathophysiology of fatal Rickettsia conorii infection in Portuguese patients.
BACKGROUND
The pathophysiologic mechanisms that determine the severity of Mediterranean spotted fever (MSF) and the host-related and microbe-related risk factors for a fatal outcome are incompletely understood.


METHODS
This prospective study used univariate and multivariate analyses to determine the risk factors for a fatal outcome for 140 patients with Rickettsia conorii infection admitted to 13 Portuguese hospitals during 1994-2006 with documented identification of the rickettsial strain causing their infection.


RESULTS
A total of 71 patients (51%) were infected with the Malish strain of Rickettsia conorii, and 69 (49%) were infected with the Israeli spotted fever (ISF) strain. Patients were admitted to the intensive care unit (40 [29%]), hospitalized as routine inpatients (95[67%]), or managed as outpatients (5[4%]). Death occurred in 29 adults (21%). A fatal outcome was significantly more likely for patients infected with the ISF strain, and alcoholism was a risk factor. The pathophysiology of a fatal outcome involved significantly greater incidence of petechial rash, gastrointestinal symptoms, obtundation and/or confusion, dehydration, tachypnea, hepatomegaly, leukocytosis, coagulopathy, azotemia, hyperbilirubinemia, and elevated levels of hepatic enzymes and creatine kinase. Some, but not all, of these findings were observed more often in ISF strain-infected patients.


CONCLUSIONS
Although fatalities and similar clinical manifestations occurred among both groups of patients, the ISF strain was more virulent than the Malish strain. Multivariate analysis revealed that acute renal failure and hyperbilirubinemia were most strongly associated with a fatal outcome.
Sousa
Rita de
Rd
Centro de Estudos de Vectores e Doenças Infecciosas, Instituto Nacional de Saúde Dr Ricardo Jorge, Faculdade de Ciências Médicas de Lisboa, Lisboa, Portugal.
França
Ana
A
Dória Nòbrega
Sónia
S
Belo
Adelaide
A
Amaro
Mario
M
Abreu
Tiago
T
Poças
José
J
Proença
Paula
P
Vaz
José
J
Torgal
Jorge
J
Bacellar
Fátima
F
Ismail
Nahed
N
Walker
David H
DH
D058186:Acute Kidney Injury / Q000097:blood / Q000382:microbiology* / Q000401:mortality / Q000473:pathology; D001907:Boutonneuse Fever / Q000453:epidemiology / Q000401:mortality / Q000503:physiopathology*; D015897:Comorbidity; D006801:Humans; D015999:Multivariate Analysis; D011174:Portugal / Q000453:epidemiology; D011446:Prospective Studies; D012282:Rickettsia Infections / Q000453:epidemiology* / Q000382:microbiology; D020114:Rickettsia conorii / Q000302:isolation & purification / Q000472:pathogenicity*; D012307:Risk Factors