An Outbreak Threat Due to Chromobacterium violaceum Pseudobacteremia in a Tertiary Health Care Center: A Cross-Sectional Study

TL;DR

A suspected outbreak of Chromobacterium violaceum bloodstream infections was found to be due to sample contamination, not actual infections.

Contribution

The study identifies a pseudo-outbreak of C. violaceum linked to sample collection practices rather than true clinical infections.

Findings

All 21 C. violaceum isolates had identical antibiotic susceptibility patterns.

Environmental samples from the ER did not yield C. violaceum, but a nearby construction site water sample did.

Patient records showed no evidence of sepsis, supporting the pseudo-outbreak conclusion.

Abstract

Background and Objective: Chromobacterium violaceum, a rare cause of sepsis, was isolated in high numbers from the blood cultures of patients over a short span of time. A nosocomial outbreak was suspected, and an epidemiological investigation was carried out to confirm the presence of an outbreak. The aim of the study is to determine whether the bloodstream infections are true clinical events or are due to sample contamination.

Methods: This cross-sectional study was done over a period of two months in 2024 at a tertiary health care center. A total of 21 C. violaceum isolates were included. An outbreak investigation was started, and samples from different environmental niches of the suspected wards were collected to trace the source of the organism. Strain typing of C. violaceum was done by antibiogram typing, comparing their susceptibilities. All the data were entered in a Microsoft Excel sheet (Redmond, USA). The results are expressed as numbers and percentages.

Results: All the 21 C. violaceum isolates had similar antibiotic susceptibility patterns. All the isolates were from blood cultures collected in the emergency room (ER). Collection of blood samples for culture in the ER was withheld, and an alternate nearby facility was used. Environmental samples from the ER did not yield growth of C. violaceum, but a water sample from a nearby construction site yielded C. violaceum. The patient’s case records were analyzed for evidence of sepsis. The patients are mostly males between the ages of 20 and 80 years.

Conclusion: Based on the circumstantial evidence, it is concluded that the threat is only a pseudo-outbreak.

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