The Spectrum of Chromobacterium violaceum Infections from a Single Geographic Location

Clinical Presentation and Outcomes Following Infection With Vibrio spp, Aeromonas spp, Chromobacterium violaceum, and Shewanella spp Water-Associated Organisms in Tropical Australia, 2015-2022

Background

Water-associated bacterial infections cause a wide spectrum of disease. Although many of these infections are typically due to human host commensal Staphylococcal or Streptococcal spp, water exposure can result in infections with environmental gram negatives such as Vibrio spp, Aeromonas spp, Chromobacterium violaceum, and Shewanella spp (collectively VACS).

Methods

We performed a retrospective analysis of the epidemiology, clinical presentation, and outcomes of deep and superficial infections associated with VACS organisms in our health service between 1 January 2015 and 31 December 2023.

Results

We identified 317 patient episodes of infection with VACS organisms over this period. Of these, Aeromonas spp (63%) was the most common, followed by Vibrio spp (19%), Shewanella spp (13%), and C violaceum (5%). The majority were isolated from males (74.4%) and involved the lower limb (67.5%). Mild infections were more common than severe presentations, with only 15 (4.7%) admissions to the intensive care unit and 8 (2.5%) deaths. Colonization occurred in 6.9% of patients, in contrast to the perceived severity of some of these bacteria. Copathogens were common and included Staphylococcus aureus (48%) and enteric bacteria (57%). The majority of patients (60%) had no documented water exposure. Initial empiric antimicrobial therapy presumptively covered the susceptibilities of the isolated organisms in 47.3% of patients; however, a lack of VACS-covering empirical therapy was not associated with readmission.

Conclusions

The isolation of a VACS organism in our setting was often not associated with documented water exposure, which has implications for empiric antimicrobial therapy. Severe disease and death were uncommon.

Regulation of virulence in Chromobacterium violaceum and strategies to combat it

Chromobacterium is a rod-shaped, Gram-negative, facultatively anaerobic bacteria with a cosmopolitan distribution. Just about 160 Chromobacterium violaceum incidents have been reported globally, but then once infected, it has the ability to cause deadly septicemia, and infections in the lungs, liver, brain, spleen, and lymphatic systems that might lead to death. C. violaceum produces and utilizes violacein to kill bacteria that compete with it in an ecological niche. Violacein is a hydrophobic bisindole that is delivered through an efficient transport route termed outer membrane vesicles (OMVs) through the aqueous environment. OMVs are small, spherical segments detached from the outer membrane of Gram-negative bacteria. C. violaceum OMV secretions are controlled by a mechanism called the quorum sensing system CviI/CviR, which enables cell-to-cell communication between them and regulation of various virulence factors such as biofilm formation, and violacein biosynthesis. Another virulence factor bacterial type 3 secretion system (T3SS) is divided into two types: Cpi-1 and Cpi-2. Cpi-1's needle and rod effector proteins are perhaps recognized by NAIP receptors in humans and mice, activating the NLRC4 inflammasome cascade, effectively clearing spleen infections via pyroptosis, and cytotoxicity mediated by IL-18-driven Natural killer (NK) cells in the liver. In this paper, we attempt to interrelate quorum-controlled biofilm formation, violacein production, violacein delivery by OMVs and T3SS effector protein production and host mediated immunological effects against the Cpi1 of T3SS. We suggest a research path with natural bioactive molecule like palmitic acid that can act as an anti-quorum agent by reducing the expression of virulence factors as well as an immunomodulatory agent that can augment innate immune defense by hyperactivation of NLRC4 inflammasome hence dramatically purge C. violaceum infections.

Increased environmental microbial diversity reduces the disease risk of a mosquitocidal pathogen

IMPORTANCE

The host-specific microbiotas of animals can both reduce and increase disease risks from pathogens. In contrast, how environmental microbial communities affect pathogens is largely unexplored. Aquatic habitats are of interest because water enables environmental microbes to readily interact with animal pathogens. Here, we focused on mosquitoes, which are important disease vectors as terrestrial adults but are strictly aquatic as larvae. We identified a pathogen of mosquito larvae from the field as a strain of Chromobacterium haemolyticum. Comparative genomic analyses and functional assays indicate this strain and other Chromobacterium are mosquitocidal but are also opportunistic pathogens of other animals. We also identify a critical role for diversity of the environmental microbiota in disease risk. Our study characterizes both the virulence mechanisms of a pathogen and the role of the environmental microbiota in disease risk to an aquatic animal of significant importance to human health.

A Rare Infection of Chromobacterium violaceum in an Immunocompetent Patient: A Case Report

Chromobacterium violaceum is a motile gram-negative bacillus. It lives in water and soil and rarely causes infection in immune-competent patients. It does not respond to the classical treatment and can cause a rapid and progressive illness. Hence, it should be considered in severe infection. Physicians are not generally aware of this organism as a possible cause of infection, and this increases the risk of mortality. Here, we described a case of a 17-year-old previously healthy girl who had severe necrotic cellulitis that progressed and spread rapidly over a few days despite the treatment with antibiotics. It started after a few days of swimming in a swimming pool. She was treated successfully with a broad spectrum of antibiotics and discharged home.

Chromobacterium violaceum causing disseminated soft tissue and pulmonary abscesses in a traveller returning from the Azores

This case report describes a 30-year-old male patient presenting with Chromobacterium violaceum cutaneous lesions who develops a subsequent bacteraemia, complicated by soft tissue and pulmonary abscesses. C. violaceum disease is a rare infection that can manifest in a spectrum from cutaneous lesions to disseminated disease and sepsis, the latter associated with high mortality. Although in the available literature there is a recommendation for a prolonged antibiotic course, we describe effective management with a shorter course of antibiotics. This case highlights the importance of not only considering a diagnosis of C. violaceum if there has been a high risk and appropriate exposure, but to also consider the changing epidemiology of the organism due to certain geographical areas becoming warmer due to climate change.

Chromobacterium violaceum: A Review of an Unexpected Scourge

Chromobacterium violaceum is a common environmental bacterium that rarely causes disease in humans but has a high fatality rate if it does. Due to the rarity of the cases, clinicians are often unaware of the rapid progression of C. violaceum infection and its unexpected antibiotic resistance pattern, which contribute to the failure of patient management. Our review provides the clinical characteristics, possible sources of exposure, and comorbidities and determines factors associated with survival. We gathered information on 132 cases of C. violaceum causing disease in humans published between 1953 and 2020. Patients were predominantly male with a median age of 17.5, interquartile range (IQR) of 5.0-40.0 years, and a third of them were known to have immune deficiencies or comorbidities. Portals of entry were mainly through a wound in the leg and feet (28.0%), the torso (8.5%), or hands and arms (6.8%). It is not uncommon to acquire infection through unintended contact with contaminated water or dust through the mouth or inhalation. The median incubation period is 4.0 days (IQR 2.0-8.0 days) with a duration of clinical course of 17.5 days (IQR 8.0-30.8 days). The high rate of positive blood cultures (56.1%) and abscesses in internal organs (36.4%) shows the significant severity of this disease. Sepsis and Bacteremia were related to mortality with a risk ratio (RR) of 5.20 (95% CI, 0.831-32.58) and 2.14 (95% CI, 1.05-4.36), respectively. Appropriate antibiotic use prevented death at a RR 0.33 (95% CI, 0.21-0.52). Most patients who recovered and survived were treated with aminoglycosides, fluoroquinolones and carbapenems. This review shows the malignant nature of C. violaceum infection and the need for clinicians to be aware and provide prompt source management for patients. Appropriate empiric and targeted antibiotic regiment guided by susceptibility test results is of vital importance.

Chromobacterium violaceum Periareolar Infection, First Non-Lethal Case in Colombia: Case Report and Literature Review

Chromobacterium violaceum is a facultative anaerobic, Gram-negative rod found in different ecosystems, especially tropical and subtropical areas. Human infections are rare, and just a few cases have been reported in literature. In this paper, we present the first non-lethal infection due to Chromobacterium violaceum, in an adult male with polycystic kidney disease in Colombia. Periareolar soft tissue infection was documented with isolation of Chromobacterium violaceum. Clinical manifestations, treatment, and outcome are shown.

Chromobacterium violaceum infection on lower limb skin: A case report

RATIONAL

Chromobacterium violaceum is a motile gram-negative bacterium. This bacterium commonly grows in tropical or subtropical areas in sewage and can cause opportunistic infections.

PATIENT CONCERNS

A 50-year-old Chinese man had a skin ulcer in the middle of his left leg in front of the tibia. The diameter of the wound was 3.0 cm, the exudation was obvious, and necrotic tissue was attached to the wound. One week previously, he was working in a field where he accidentally punctured his left leg.

DIAGNOSIS

C violaceum infection was diagnosed as per the results of pathogen culture from the infection site.

INTERVENTIONS

He was treated with piperacillin/tazobactam (3.375 g/12 h iv) and levofloxacin (0.5 g/24 h iv) for 5 days.

OUTCOMES

The patient showed good response to therapy and was discharged on day 18 after wound healing.

LESSONS

C violaceum rarely infects humans. When an infection is suspected, samples should be immediately sent for microbial culture. Timely treatment on the basis of drug sensitivity test results can prevent further complications.

Pediatric osteomyelitis due to rare tropical multi-drug resistance (MDR) organisms: a treatment quandary

Osteomyelits due to concurrent multi-drug resistance organisms is difficult to treat for any surgeon and infectious disease physician. An eleven-year-old boy presenting with an open fracture of the left radius and ulna after a fall in a stagnant wet field. Despite prophylactic antibiotics and surgical intervention, the open wound was infected, and Chromobacterium violaceum as well as Klebsiella pneumoniae were isolated. He was treated with six weeks of parenteral cefepime and amikacin and was discharged upon clinical improvement. Unfortunately, chronic osteomyelitis set in with persistent sinus drainage. He then underwent a second procedure for debridement of the wound and Burkholderia pseudomallei was isolated. Parenteral antibiotic therapy was initiated progressing with a marked improvement. However, the long course of antibiotics had exhausted the patient and his family, leading to a premature interruption of the parenteral antibiotic. Despite the suboptimal antibiotic course, there were no signs of relapsed osteomyelitis during subsequent review. The timely surgical intervention with appropriate sampling for subsequent microorganism isolation guided the suitability of the treatment line.

Agricultural Injury-Associated Chromobacterium violaceum Infection in a Bangladeshi Farmer

Chromobacterium violaceum is an emerging environmental pathogen that causes life-threatening infection in humans and animals. In October 2017, a Bangladeshi farmer was hospitalized with high-grade fever due to an agricultural injury-related wound infection. Bacteriological and 16S rRNA gene investigation detected C. violaceum in the wound discharge. The patient recovered successfully after a combination treatment with meropenem and ciprofloxacin, followed by prolonged medication to avoid recurrence. We strongly propose to incorporate C. violaceum in the differential diagnosis of wound and skin infections occurring in tropical and subtropical regions, especially when the injury was exposed to soil or sluggish water.

Quorum Sensing Signal Selectivity and the Potential for Interspecies Cross Talk

Many species of proteobacteria communicate with kin and coordinate group behaviors through a form of cell-cell signaling called acyl-homoserine lactone (AHL) quorum sensing (QS). Most AHL receptors are thought to be specific for their cognate signal, ensuring that bacteria cooperate and share resources only with closely related kin cells. Although specificity is considered fundamental to QS, there are reports of "promiscuous" receptors that respond broadly to nonself signals. These promiscuous responses expand the function of QS systems to include interspecies interactions and have been implicated in both interspecies competition and cooperation. Because bacteria are frequently members of polymicrobial communities, AHL cross talk between species could have profound impacts. To better understand the prevalence of QS promiscuity, we measured the activity of seven QS receptors in their native host organisms. To facilitate comparison of our results to previous studies, we also measured receptor activity using heterologous expression in Escherichia coli We found that the standard E. coli methods consistently overestimate receptor promiscuity and sensitivity and that overexpression of the receptors is sufficient to account for the discrepancy between native and E. coli reporters. Additionally, receptor overexpression resulted in AHL-independent activity in Pseudomonas aeruginosa Using our activation data, we developed a quantitative score of receptor selectivity. We find that the receptors display a wide range of selectivity and that most receptors respond sensitively and strongly to at least one nonself signal, suggesting a broad potential for cross talk between QS systems.IMPORTANCE Specific recognition of cognate signals is considered fundamental to cell signaling circuits as it creates fidelity in the communication system. In bacterial quorum sensing (QS), receptor specificity ensures that bacteria cooperate only with kin. There are examples, however, of QS receptors that respond promiscuously to multiple signals. "Eavesdropping" by these promiscuous receptors can be beneficial in both interspecies competition and cooperation. Despite their potential significance, we know little about the prevalence of promiscuous QS receptors. Further, many studies rely on methods requiring receptor overexpression, which is known to increase apparent promiscuity. By systematically studying QS receptors in their natural parent strains, we find that the receptors display a wide range of selectivity and that there is potential for significant cross talk between QS systems. Our results provide a basis for hypotheses about the evolution and function of promiscuous signal receptors and for predictions about interspecies interactions in complex microbial communities.

Chromobacterium violaceum in Northern Australia: A Sheep in Wolf's Clothing?

In many parts of the world, the case-fatality rate of Chromobacterium violaceum infection approaches 60%. To evaluate the spectrum of disease associated with C. violaceum in Far North Queensland (FNQ), Australia, we reviewed all culture-confirmed isolates from 1997 to 2017. There were 28 isolates, 15 represented infection, 11 were contaminants, and two charts were destroyed preventing detailed evaluation of these cases. The most common sites of infection were the skin and soft tissue and the urinary tract; there were two cases of bacteremia without focus. There were no deaths attributable to C. violaceum during the study period and only two cases required intensive care unit support, although in both patients this was not for the C. violaceum infection, but for the management of other health issues. Globally, C. violaceum has a reputation as a deadly pathogen, but in FNQ, Australia, infections usually follow a relatively benign course.

Action and function of Chromobacterium violaceum in health and disease: Violacein as a promising metabolite to counteract gastroenterological diseases

Chromobacterium violaceum is a Gram negative, β-proteobacterium found in the microbiota of tropical and subtropical environments. Although considered an opportunistic pathogen, infection rapidly progress to fatal sepsis, with metastatic abscesses. It is noteworthy the multidrug resistant phenotype of C. violaceum and the possibility of relapse. Recently, an influence of global climate in the incidence of cases beyond the previous areas has been observed. Furthermore, chronic granulomatous disease has been considered a risk factor to infection. Despite the increase in C. violaceum infection incidence and high mortality, most clinicians are not familiar with it. This review pointed out important features of this life threatening microorganism, including its pathogenicity, mechanistic aspects, genetic and drug resistance associated factors, and the clinical association with chronic granulomatous disease. In addition, its main metabolite violacein may be a promising agent to counteract gastroenterological diseases, such as colorectal cancer and inflammatory gastric lesions.

Multiple Liver Abscesses with a Skin Pustule due to Chromobacterium violaceum

A 69-year-old woman was admitted to our hospital with the chief complaints of fever and fatigue. We initially treated the patient for a tick-borne disease after noticing a pustule on her leg; however, abdominal computed tomography (CT) showed multiple low-density areas in the liver and Chromobacterium violaceum was isolated from a blood culture. We diagnosed her with multiple liver abscesses secondary to Chromobacterium violaceum bacteremia. The patient was successfully treated with ciprofloxacin.

Chromobacterium violaceum infection in chronic granulomatous disease: a case report and review of the literature

Introduction.Chromobacterium violaceum is an opportunistic human pathogen, associated with significant mortality, and has been reported in patients with chronic granulomatous disease (CGD), a genetic condition causing impaired phagocytosis.

Case presentation. A 28-year-old man with a history of CGD presented with fever, pharyngitis, cervical lymphadenopathy and internal jugular vein thrombosis, following travel to the rural Solomon Islands. C. violaceum was recovered from his blood. The patient recovered after treatment with meropenem and trimethoprim/sulfamethoxazole.

Conclusion. To the best of our knowledge, this is the first case report of internal jugular vein thrombophlebitis (Lemierre’s syndrome) caused by C. violaceum in a patient with CGD. A review of the literature demonstrated that the diagnosis of C. violaceum preceded the diagnosis of CGD in the majority of cases. This case emphasizes the importance of this organism in patients with CGD who live in or visit tropical areas.