P-577. Clinical Predictors of Mortality in Hospitalized Patients with Rickettsioses in Northern Mexico

TL;DR

This study identifies key clinical factors that predict mortality in hospitalized patients with rickettsioses in Northern Mexico.

Contribution

The study provides new insights into mortality predictors for rickettsioses, including thrombocytopenia and elevated lactate levels.

Findings

Thrombocytopenia, elevated lactate, and increased creatinine levels were significant predictors of mortality.

Fever was a common symptom, but rash was observed in fewer than half of the patients.

Most patients received doxycycline, but prior antibiotic use included ceftriaxone and amoxicillin/clavulanic acid.

Abstract

Rickettsioses are life-threatening vector-borne infections1. Clinical manifestations are nonspecific, commonly including fever, malaise, and an exanthematous rash, necessitating a high index of suspicion for timely diagnosis. Without appropriate treatment, mortality can reach 100%2.

From October 2022 to April 2025, we conducted a prospective study of patients with qPCR-confirmed rickettsioses at a tertiary teaching hospital in Monterrey, Mexico. Data were analyzed using SPSS v19. We applied Student’s t-test and chi-square test for group comparisons and calculated relative risks (RR).

A total of 49 patients were included, with a median age of 15 years (range 9-32 years), and 52% were males. Thirty patients (60%) died during hospitalization.

The media time-to-treatment from hospital admission was 5.15 hours. All patients received doxycycline. Some patients received antibiotics prior to admission, including ceftriaxone and amoxicillin/clavulanic acid; only three received doxycycline.

The median number of medical visits before diagnosis was 1 day (range 1-2)

Symptom duration before admission had a median of 5 days (range 4-7). Fever (98%) and petechial rash (42%) were the most common clinical signs shown in Table 1, while thrombocytopenia was present in 98% of patients.

Factors associated with increased mortality were thrombocytopenia RR 4 (95% CI 1.12-14.25) p = 0.03, elevated lactate RR 3.28 (95% CI 1.19.9.95) p = 0.02, increased creatinine RR 2.26 (95% CI 1.2-4.25) p = 0.01 and aspartate aminotransferase (AST) levels RR 2.33 (95% CI 1-5.43) p = 0.03, as shown in Table 3.

Rickettsioses are a critical illness associated with high mortality. In our cohort, fever was a common presenting symptom, while rash was observed in fewer than half of the patients; notably, 98% of the patients presented with thrombocytopenia. Elevated lactate levels, acute kidney injury, and thrombocytopenia at admission were significant predictors of mortality.

All Authors: No reported disclosures

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