Necrotizing Pneumonia Caused by Chromobacterium violaceum: Report of a Rare Human Pathogen Causing Disease in an Immunodeficient Child

Synthesis of the Novel N-(2-Hexadecynoyl)-l-Homoserine Lactone and Evaluation of Its Antiquorum Sensing Activity in Chromobacterium violaceum

Chromobacterium violaceum is commonly found in soil and freshwater within tropical and subtropical regions. Although not a common occurrence, this bacterium has the potential to cause severe diseases in humans and animals, such as liver and lung abscesses and septicemia. Herein we report the synthesis of novel N-acyl homoserine lactones (HSLs) to evaluate their effectiveness as antiquorum sensing (anti-QS) agents in C. violaceum. The HSLs were prepared through three synthetic approaches, where hexanoic acid, decanoic acid, 6-decynoic acid, or 2-hexadecynoic acid (2-HDA) was treated with commercially available l-homoserine lactone (HSL) hydrobromide in either dichloromethane or tetrahydrofuran in the presence of EDC and DMAP. The effectiveness of HSLs as anti-QS agents was assessed through susceptibility tests and violacein quantification. The most effective anti-QS inhibitor among all N-acyl-HSLs tested was the N-(2-hexadecynoyl)-l-homoserine lactone (HSL 4). Further experimental approaches, such as quantification of acyl-homoserine lactones and biofilm inhibitory tests, were carried out to determine the effect of HSL 4 on these QS-dependent mechanisms. These experiments showed that HSL 4 was highly effective at inhibiting the production of HSLs and biofilm in C. violaceum at 0.25, 0.50, and 1 mg/mL. In addition, the cytotoxicity activity was evaluated against Vero cells to determine the selectivity of HSL 4 as a nontraditional antibacterial agent. HSL 4 was not toxic against Vero cells at concentrations ranging from 0.0039 to 1 mg/mL. Molecular docking experiments were conducted to study the interactions between novel HSLs and CviR (PDB ID 3QP5), a receptor that plays a significant role in C. violaceum QS. In silico studies indicate that HSL 4 exhibits better interactions with Leu 72 and Gln 95 of the CviR binding pocket when compared to the other analogs. These results validate previous in vitro studies, such as susceptibility tests and violacein production assays. The findings above indicate that novel acetylenic HSLs may potentially be agents that combat bacterial communication and biofilm formation. However, further investigation is necessary to expand the spectrum of bacterial strains capable of resisting antibiotics through QS and evaluate the compounds' cytotoxicity in other cell lines.

Critical bloodstream infection caused by Chromobacterium violaceum: a case report in a 15-year-old male with sepsis-induced cardiogenic shock and purpura fulminans

Chromobacterium violaceum (C. violaceum) is a gram-negative bacillus that is widespread in tropical and subtropical areas. Although C. violaceum rarely infects humans, it can cause critical illness with a mortality rate above 50%. Here, we report the successful treatment of a 15-year-old male who presented with bloodstream infection of C. violaceum along with sepsis, specific skin lesions, and liver abscesses. Cardiogenic shock induced by sepsis was reversed by venoarterial extracorporeal membrane oxygenation (VA ECMO). Moreover, C. violaceum-related purpura fulminans, which is reported herein for the first time, was ameliorated after treatment. This case report demonstrates the virulence of C. violaceum with the aim of raising clinical awareness of this disease.

Necrotizing Pneumonia in Children: Early Recognition and Management

Necrotizing pneumonia (NP) is an uncommon complicated pneumonia with an increasing incidence. Early recognition and timely management can bring excellent outcomes. The diagnosis of NP depends on chest computed tomography, which has radiation damage and may miss the optimal treatment time. The present review aimed to elaborate on the reported predictors for NP. The possible pathogenesis of Streptococcus pneumoniae, Staphylococcus aureus, Mycoplasma pneumoniae and coinfection, clinical manifestations and management were also discussed. Although there is still a long way for these predictors to be used in clinical, it is necessary to investigate early predictors for NP in children.

Characterization and Whole Genome Sequencing of Chromobacterium violaceum OUAT_2017: A Zoonotic Pathogen Found Fatal to a Wild Asiatic Elephant

This study reports a rare fatal case of Chromobacterium violeceum OUAT_2017 strain infection in an Asiatic elephant calf in India. Necropsy revealed pus-filled nodules in liver, spleen, and lungs. Nutrient broth cultures of nodule content showed sediment of violet pigment whereas smooth, non-diffusible, violet-pigmented, homogeneous colonies appeared on nutrient agar. The organism was found to be non-haemolytic and resistant to 8 of the 24 antibiotics tested in vitro. Partial 16S rRNA gene sequence measuring 1410 bp revealed 97% homology with C. violeceum. The bacterial genome composed of 64.87% of G + C content with total size of 4,681,202 bp. The genome annotation has 42 genes responsible for multidrug antibiotic resistance with the presence of Aminoglycoside-modifying enzymes (AAC (6')) that targets streptomycin and spectinomycin. Our findings corroborated the lethal effect of C. violeceum in a new host (elephant) that enriched scientific information on epidemiological picture and whole genome sequencing as well.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-022-01047-4.

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.

Clinical and demographic pattern of chronic granulomatous disease (CGD) from a multicenter perspective: Malaysia's experience over 26 years

Background

A retrospective review of clinical manifestations and demographic pattern of patients diagnosed as chronic granulomatous disease (CGD) from 7 hospitals in Malaysia. An analysis of the available database would establish clinical characteristics, diagnoses and outcome including microbiologic pattern. Studying the demography allows us to document the occurrence of CGD amongst multiethnic groups and its geographical distribution for Malaysia.

Methods

Data from the Malaysia Primary Immunodeficiency Network (MyPIN) with cases of CGD diagnosed from 1991 until 2016 were collated and analysed.

Results

Twenty patients were diagnosed as CGD. Males (N = 13, 65%) outnumber females (N = 7, 35%). CGD is commonest amongst the Malays (65%) followed by the Chinese (15.0%), Indians (10.0%) and natives of Borneo (10.0%), reflecting the ethnic composition of the country. The mean age of diagnosis was 3.7 years. There was a positive family history in 40% of the cases. Abscess was the main presenting feature in 16 patients (80%) with one involving the brain. Pneumonia occurred in 10 (50%) and one with complicated bronchiectasis. Catalase-positive bacteria were the most commonly isolated pathogen with Chromobacterium violaceum predominating (N = 5, 25%) with consequent high mortality (N = 4, 80%). All CGD patients with C. violaceum infection displayed CD4 + (T helper cells) lymphopenia.

Conclusion

This study has shown CGD occurs in the major ethnic groups of Malaysia. To the best of our knowledge, this is the first and the largest series of chronic granulomatous disease in South East Asia which may be reflective of similar clinical pattern in the region. C. violaceum infection is associated with a higher mortality in CGD patients in Malaysia. All the CGD patients with C. violaceum infection in this patient series displayed CD4 + (T helper) lymphopenia. We recorded rare clinical manifestation of CGD viz. brain abscess and bronchiectasis.

Sepsis in cougar (Puma concolor) associated with Chromobacterium violaceum

The genus Chromobacterium is widely distributed in the environment and is composed of Gram-negative, aerobic, or facultative anaerobic bacilli that occur in violet-colored colonies. These bacteria rarely cause infections, but when it occurs, it spreads quickly and has a high mortality. Because diseases are infrequent, the diagnosis is often delayed, and it takes time for suitable treatment to be initiated, leading to increased mortality due to the rapid progression of the disease. After the death of a cougar, serologically positive for feline leukemia virus, at the Center for Medicine and Research on Wild Animals of the Federal University of Mato Grosso, an autopsy was carried out, and fragments of its organs were sent for bacterial culture. Significant lesions were found, mainly in the liver and lungs, and upon bacterial isolation, violet-colored colonies were obtained from all of the referred organs, suggestive of C. violaceum, which was later confirmed by 16S DNA sequencing. The objective of this study was to report a case of death associated primarily with disseminated infection caused by C. violaceum in a FeLV-positive wild cougar in July 2018; no other occurrence in this species has yet been described.