Analysis of Genetic Diversity and Antibiotic Options for Clinical Listeria monocytogenes Infections in China

Association of Virulence, Biofilm, and Antimicrobial Resistance Genes with Specific Clonal Complex Types of Listeria monocytogenes

Precise classification of foodborne pathogen Listeria monocytogenes is a necessity in efficient foodborne disease surveillance, outbreak detection, and source tracking throughout the food chain. In this study, a total of 150 L. monocytogenes isolates from various food products, food processing environments, and clinical sources were investigated for variations in virulence, biofilm formation, and the presence of antimicrobial resistance genes based on their Whole-Genome Sequences. Clonal complex (CC) determination based on Multi-Locus Sequence Typing (MLST) revealed twenty-eight CC-types including eight isolates representing novel CC-types. The eight isolates comprising the novel CC-types share the majority of the known (cold and acid) stress tolerance genes and are all genetic lineage II, serogroup 1/2a-3a. Pan-genome-wide association analysis by Scoary using Fisher's exact test identified eleven genes specifically associated with clinical isolates. Screening for the presence of antimicrobial and virulence genes using the ABRicate tool uncovered variations in the presence of Listeria Pathogenicity Islands (LIPIs) and other known virulence genes. Specifically, the distributions of actA, ecbA, inlF, inlJ, lapB, LIPI-3, and vip genes across isolates were found to be significantly CC-dependent while the presence of ami, inlF, inlJ, and LIPI-3 was associated with clinical isolates specifically. In addition, Roary-derived phylogenetic grouping based on Antimicrobial-Resistant Genes (AMRs) revealed that the thiol transferase (FosX) gene was present in all lineage I isolates, and the presence of the lincomycin resistance ABC-F-type ribosomal protection protein (lmo0919_fam) was also genetic-lineage-dependent. More importantly, the genes found to be specific to CC-type were consistent when a validation analysis was performed with fully assembled, high-quality complete L. monocytogenes genome sequences (n = 247) extracted from the National Centre for Biotechnology Information (NCBI) microbial genomes database. This work highlights the usefulness of MLST-based CC typing using the Whole-Genome Sequence as a tool in classifying isolates.

Treatment failure in a patient infected with Listeria sepsis combined with latent meningitis: A case report

BACKGROUND

Listeria is a food-borne disease, which is rarely prevalent in the normal population; it mostly occurs in pregnant women, newborns, immunodeficiency patients, and the elderly. The main manifestations of this disease in patients include sepsis, meningitis, etc, and the mortality rate remains high, although the onset of meningitis is relatively insidious.

CASE SUMMARY

A 75-year-old man presented with a fever for 1 wk and was admitted to the hospital for diagnosis and management of a lung infection. His condition improved after receiving anti-infective treatment for 2 wk. However, soon after he was discharged from the hospital, he developed fever again, and gradually developed various neurological symptoms, impaired consciousness, and stiff neck. Thereafter, through the cerebrospinal fluid metagenomic testing and blood culture, the patient was diagnosed with Listeria monocytogenes meningitis and sepsis. The patient died after being given active treatment, which included penicillin application and invasive respiratory support.

CONCLUSION

This case highlights the ultimate importance of early identification and timely application of the various sensitive antibiotics, such as penicillin, vancomycin, meropenem, etc. Therefore, for high-risk populations with unknown causes of fever, multiple blood cultures, timely cerebrospinal fluid examination, and metagenomic detection technology can assist in confirming the diagnosis quickly, thereby guiding the proper application of antibiotics and improving the prognosis.

Clinical and Laboratory Characteristics of Patients infected by Listeria monocytogenes at a Tertiary Hospital in Hefei City, China

Background

Human listeriosis is a severe foodborne infection caused by Listeria monocytogenes and the data of patients with this infection are largely limited for the Hefei population.

Purpose

This is a retrospective study that evaluated the clinical and laboratory data of patients with listeriosis at a tertiary hospital in Hefei City.

Patients and Methods

A total of 24 listeriosis patients were admitted to the First Affiliated Hospital of Anhui Medical University from January 2003 to July 2021. Data from all patients were collected from the hospital’s electronic medical records.

Results

The most common symptom of all patients was fever (91.7%), followed by altered consciousness (50.0%), rashes (45.8%), respiratory distress symptoms (37.5%), nuchal rigidity (29.2%), and headaches (20.8%). Laboratory results also indicated elevated C-reactive protein (CRP) (79.1%), hypoproteinemia (75.0%), anemia (62.5%), leukocytosis (45.8%), and neutrophilia (45.8%). The mean value of 5.1 μg/mL (SD, 3.8) for D‐dimer (D‐D) was significantly higher than the normal value ((0.00–0.50) μg/mL), while both altered consciousness (6 vs 4, P = 0.034) and headaches (4 vs 1, P = 0.036) occurred more frequently in the neurolisteriosis group compared with the bacteremia one. Additionally, the mean maximal body temperature (°C) (40.5 ± 0.7) as well as white blood cell (WBC) (15.3 vs 7.5 ×10⁹/L, P = 0.014) and neutrophil (NEUT#) (13.2 vs 6.1 ×10⁹/L, P = 0.026) counts of neurolisteriosis patients were higher than those of bacteremia (39.4 ± 0.4) (P = 0.001). Of all patients, four (50%) from the maternal-neonatal group remained uncured.

Conclusion

Listeriosis is a rare disease with extremely variable clinical characteristics in Hefei City. Our data indicated that unexplained fever, altered consciousness, hypoproteinemia, anemia, elevated CRP and DD should be considered to assist diagnosis of listeriosis for early treatment interventions.

Genomic and Phenotypic Characteristics for Vibrio vulnificus Infections

Background

Vibrio vulnificus (VV) is a causative agent of foodborne diseases with high mortality. The aim of this study was to investigate the genomic and phenotypic profiles of VV.

Methods

Six VV isolates were collected and conducted whole-genome sequencing. Biofilm formation and anti-complement killing test were performed to evaluate the pathogenicity. Subsequently, 157 publicly available genomes of VV isolates were selected to determine the evolutionary relationship.

Results

The resistant genes norM and tet34 were identified in six isolates. A total of 156 virulence genes were identified. However, there is no obvious difference between strains isolated from blood and puncture fluid. The tendency of growth for six isolates decreased with the lapse of time, while the biofilm formation increased. The genes tadC and flp related to Flp pili were found in isolate 25506 and 30896, resulting in more obvious biofilm formation. In addition, the survival rate of 19656 was less than 20% due to lack of one genomic island including virulence genes (impD-H, clpV-1) relevant to type VI secretion system (T6SS). Multi-locus sequence typing (MLST) revealed 95 different STs and 19 novel STs, indicating that the tendency of 163 isolates was sporadic. Further comparative genomics analysis clearly classified 163 isolates into three distinct evolutionary lineages.

Conclusion

VV infections were sporadic in humans and the environment. Virulence genes impD-H and clpV-1 related to T6SS were associated with pathogenicity phenotype of VV.