The clinical characteristics of adult bacterial meningitis caused by non-Pseudomonas (Ps.) aeruginosa Pseudomonas species: A clinical comparison with Ps. aeruginosa meningitis

Bacteria of Zoonotic Interest Identified on Edible Freshwater Fish Imported to Australia

Previous research has shown that freshwater edible fish imported into Australia are not compliant with Australian importation guidelines and as a result may be high risk for bacterial contamination. In the present study, the outer surface of imported freshwater fish were swabbed, cultured, confirmatory tests performed and antimicrobial patterns investigated. Channidae fish (Sp. A/n = 66) were contaminated with zoonotic Salmonella sp./Staphylococcus aureus (n = 1/66) and other bacteria implicated in cases of opportunistic human infection, these being Pseudomonas sp. (including P. mendocina and P. pseudoalcaligenes (n = 34/66)); Micrococcus sp. (n = 32/66); Comamonas testosteroni (n = 27/66) and Rhizobium radiobacter (n = 3/66). Pangasiidae fish (Species B/n = 47) were contaminated with zoonotic Vibrio fluvialis (n = 10/47); Salmonella sp. (n = 6/47) and environmental bacteria Micrococcus sp. (n = 3/47). One sample was resistant to all antimicrobials tested and is considered to be Methicillin Resistant S. aureus. Mud, natural diet, or vegetation identified in Sp. A fish/or packaging were significantly associated with the presence of Pseudomonas spp. The study also showed that visibly clean fish (Sp. B) may harbour zoonotic bacteria and that certain types of bacteria are common to fish groups, preparations, and contaminants. Further investigations are required to support the development of appropriate food safety recommendations in Australia.

Pseudomonas paralcaligenes sp. nov., isolated from a hospitalized patient

A Gram-stain-negative, aerobic, rod-shaped, non-endospore-forming bacterium, designated as strain MRCP1333^T, was isolated from a faecal sample from a hospital patient in Japan. MRCP1333^T grew at temperatures of 15-40 °C (optimum 25-35 °C), with 1.0-3.0 % (w/v, 171-513 mM) NaCl [optimum 1-2 % (w/v), 171-342 mM], and at pH 6.0-9.5 (optimum pH 7.0-8.0). The results of phylogenetic analysis based on the sequences of the 16S rRNA gene and the 53 genes encoding the bacterial ribosome protein subunits indicated that MRCP1333^T represented a member of the Pseudomonas aeruginosa group, most closely related to Pseudomonas alcaligenes. Whole-genome comparisons, using average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity, confirmed that MRCP1333^T represented a distinct species in the P. aeruginosa group. Phenotypic characterization tests demonstrated utilization by this strain of citrate, glycerol, and d-malic acid, the ability to reduce nitrite to nitrogen and the ability of this strain to grow in the presence of minocycline and tetrazolium blue, distinguishing this strain from P. alcaligenes and other closely related species of the P. aeruginosa group. The major fatty acids of MRCP1333^T were summed feature 8 (C_18 : 1ω7c/C_18 : 1ω6c; 38.4 %), summed feature 3 (C_16 : 1ω7c/C_16 : 1ω6c; 21.1 %) and C_16 : 0 (20.6 %). The DNA G+C content of MRCP1333^T was 66.5 mol%. Genetic and phenotypic evidence indicated that MRCP1333^T should be classified as representing a novel species, for which the name Pseudomonas paralcaligenes sp. nov. is proposed. The type strain is MRCP1333^T (=LMG 32254^T,=JCM 34250^T).

Pseudomonas fluorescens Complex and Its Intrinsic, Adaptive, and Acquired Antimicrobial Resistance Mechanisms in Pristine and Human-Impacted Sites

Pseudomonas spp. are ubiquitous microorganisms that exhibit intrinsic and acquired resistance to many antimicrobial agents. Pseudomonas aeruginosa is the most studied species of this genus due to its clinical importance. In contrast, the Pseudomonas fluorescens complex consists of environmental and, in some cases, pathogenic opportunistic microorganisms. The records of antimicrobial-resistant P. fluorescens are quite scattered, which hinders the recognition of patterns. This review compiles published data on antimicrobial resistance in species belonging to the P. fluorescens complex, which were identified through phylogenomic analyses. Additionally, we explored the occurrence of clinically relevant antimicrobial resistance genes in the genomes of the respective species available in the NCBI database. Isolates were organized into two categories: strains isolated from pristine sites and strains isolated from human-impacted or metal-polluted sites. Our review revealed that many reported resistant phenotypes in this complex might be related to intrinsic features, whereas some of them might be ascribed to adaptive mechanisms such as colistin resistance. Moreover, a few studies reported antimicrobial resistance genes (ARGs), mainly β-lactamases. In-silico analysis corroborated the low occurrence of transferable resistance mechanisms in this Pseudomonas complex. Both phenotypic and genotypic assays are necessary to gain insights into the evolutionary aspects of antimicrobial resistance in the P. fluorescens complex and the possible role of these ubiquitous species as reservoirs of clinically important and transmissible ARGs.

First report of Pseudomonas mosselii causing white blotch disease in Pleurotus pulmonarius in China

Pleurotus pulmonarius is a popular and widely cultivated edible mushroom in China. In November 2021, white blotch disease (3% incidence) was observed on the cap of P. pulmonarius, growing in a mushroom farm in Nanning, China. Initially, white blotch (0.7-1.6 cm) appeared on the cap of the young P. pulmonarius, which expanded gradually as the cap grew. However, the fruiting bodies still grew well without rotting. The pathogen causing this phenomenon was isolated from infected cap tissues using a dilution plate technique, sections of tissue (approximately 5×5×5 mm) with white blotch were rinsed three times in sterile deionized water, then, mashed in the sterile 2 ml eppendorf tubes, 1000µl sterile water was added and the suspension was diluted into eight concentrations (10-1~10-8). From each concentration, 120µl suspension was spread on Luria Bertani (LB) medium and incubated for 24 hours at 28°C. Both 10-5 and 10-6 suspensions had single colonies, the dominant single colonies were picked and purified 2-3 times. The purified colonies were round, beige, and opaque, with a raised center and regular, smooth and moist margins. This bacterium is gram negative, short rod-shaped, single polar flagellum, motile, without pods or endospores, and produced fluorescent pigments on King's B medium. Amplified 16S rDNA (1396 bp; OM022022) of four randomly selected colonies using universal primers 27f/1492r, exhibited 100% identity with Pseudomonas (Ps.) mosselii. The partial sequences of the rpoB (1173bp; OM202622), rpoD (734bp; ON469579), gyrB (1383bp; OM202621) and recA (887bp; ON469580) genes of four selected colonies were amplified using primers LAPS5/LAFS27(Tayeb et al. 2005.), PsEG30F/PsEG790R (Mulet et al. 2009), gyrB-R/gyrB-F (Agaras et al. 2018) and recA-F (5'-3' ACGACAACAAGAAGCGCGCCTT)/recA-R (5'-3' CAATGGCCGGGTTCTCTTGCAGGTA) designed in this study, respectively, also exhibited 99%~100% similarities to Ps. mosselii. Phylogenetic analysis showed that isolates cluster with Ps. mosselii. The biochemical tests for isolates were performed via bacterial micro-biochemical reaction tubes (Hangzhou Microbial Reagent Co., LTD), and the results showed the same biochemical characteristics as Ps. mosselii (Positive for arginine dihydrolase, trisodium citrate, urea, lysine, arginine, ornithine and gelatin. Negative for glucosamine, lactose, galactose, rhamnose, maltose, sucrose, arabinose, mannose, xylose, esculoside, inositol, nitrate reduction and malonate) (Dabboussi et al.2002; Soto-Rodriguez et al. 2013). The isolates were identified as Ps. mosselii based on biochemical tests and phylogenetic analysis. This isolate was incubated in LB Broth at 28℃, 160 rpm for 24h and the bacterial cells were collected by centrifugation at 4000 rpm for 10min. The collected bacterial cells were resuspended in sterile deionized water to make a bacterial suspension. For pathogenicity tests, 30µl of bacterial suspension (approximately 1x10^9 CFU/mL) was added to the surface of the cap (3-4cm) of young P. pulmonarius. Sterile deionized water was added as a negative control. All treatments were incubated at 22°C and 80-85% humidity. The experiment was repeated three times with three bags each time. 12 h later, white blotches were visible on all parts of the inoculated mushroom. This disease symptoms were similar to those observed in the original samples. However, no disease phenomena were observed in the negative control group. After the pathogenicity test, we obtained the same pathogen as the initially isolates from infected tissues based on morphological characteristics, 16S rDNA sequences, rpoB, rpoD, gyrB and recA sequences, and biochemical test results. Ps. mosselii was first isolated clinically and described by Dabboussi et al. (2002). It has shown to be pathogenic to Oreochromis niloticus and humans (Soto-Rodriguez et al. 2013; Peña et al. 2019; Leneveu-Jenvrin et al. 2013; Huang et al. 2018.). However, to the best of our knowledge, this is the first report of Ps. mosselii causing white blotch disease in P. pulmonarius worldwide, which negatively affects the commercial value of P. pulmonarius and requires attention of mushroom industry.

CRISPR/Cas9–Mediated Genome Editing for Pseudomonas fulva, a Novel Pseudomonas Species with Clinical, Animal, and Plant–Associated Isolates

As one of the most widespread groups of Gram–negative bacteria, Pseudomonas bacteria are prevalent in almost all natural environments, where they have developed intimate associations with plants and animals. Pseudomonas fulva is a novel species of Pseudomonas with clinical, animal, and plant–associated isolates, closely related to human and animal health, plant growth, and bioremediation. Although genetic manipulations have been proven as powerful tools for understanding bacterial biological and biochemical characteristics and the evolutionary origins, native isolates are often difficult to genetically manipulate, thereby making it a time–consuming and laborious endeavor. Here, by using the CRISPR–Cas system, a versatile gene–editing tool with a two–plasmid strategy was developed for a native P. fulva strain isolated from the model organism silkworm (Bombyx mori) gut. We harmonized and detailed the experimental setup and clarified the optimal conditions for bacteria transformation, competent cell preparation, and higher editing efficiency. Furthermore, we provided some case studies, testing and validating this approach. An antibiotic–related gene, oqxB, was knocked out, resulting in the slow growth of the P. fulva deletion mutant in LB containing chloramphenicol. Fusion constructs with knocked–in gfp exhibited intense fluorescence. Altogether, the successful construction and application of new genetic editing approaches gave us more powerful tools to investigate the functionalities of the novel Pseudomonas species.

Whole-Genome Sequencing-Based Re-Identification of Pseudomonas putida/fluorescens Clinical Isolates Identified by Biochemical Bacterial Identification Systems

The genus Pseudomonas, a complex Gram-negative genus, includes species isolated from various environments, plants, animals, and humans. We compared whole-genome sequencing (WGS) with clinical bacteriological methods and evaluated matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify Pseudomonas species. Clinical isolates (N = 42) identified as P. putida or P. fluorescens by a bacterial identification system based on biochemical properties were reexamined by another identification system based on biochemical properties, two systems based on MALDI-TOF MS, and WGS. WGS revealed that 30 of the 42 isolates belonged to one of 14 known Pseudomonas species, respectively. The remaining 12 belonged to one of 9 proposed novel Pseudomonas species, respectively. MALDI-TOF MS analysis showed that the 9 novel species had unique major peaks. These results suggest that WGS is the optimal method to identify Pseudomonas species and that MALDI-TOF MS may complement WGS in identification. Based on their morphologic, physiologic, and biochemical properties, we propose nine novel Pseudomonas species.

IMPORTANCE Most of the clinical isolates, identified as P. putida or P. fluorescens, were misidentified in clinical laboratories. Whole-genome sequencing (WGS) revealed that these isolates belonged to different Pseudomonas species, including novel species. WGS is a gold-standard method to identify Pseudomonas species, and MALDI-TOF MS analysis has the potential to complement WGS to reliably identify them.

Pseudomonas mendocina Urinary Tract Infection: A Case Report and Literature Review

Pseudomonas mendocina is a Gram-negative bacillus from the family Pseudomonadaceae. The first P. mendocina-related infection was reported in 1992. Although a rare cause of infections, P. mendocina has been known to cause severe infections that require intensive treatment. We present the first documented case of urinary tract infection caused by P. mendocina.

An 83-year-old male with a past medical history of diabetes, hypertension, coronary artery disease, and prostate cancer with bone metastases, currently being treated with abiraterone and prednisone, presented with subjective fever, fatigue, altered mental status, dysuria, and hematuria of one-week duration. He was found to have a complicated urinary tract infection with an incidental asymptomatic COVID-19 infection on admission. The patient was empirically treated with ceftriaxone and switched to cefepime for broader coverage on day two of hospitalization. Urine culture reported the presence of P. mendocina with resistance only to fluoroquinolones. Ceftriaxone was reinstated. The patient was successfully treated with a seven-day course of ceftriaxone (days 1-3, days 6-7) and cefepime (days 4-5) but continued to remain inpatient for a later symptomatic COVID-19 pneumonia with discharge on day 15.

The majority of P. mendocina infections present as skin and soft tissue infections, infective endocarditis, meningitis, and bacteremia. Ours is the first documented case of urinary tract infection caused by P. mendocina, particularly in an immunocompromised COVID-19 patient, and the second to report P. mendocina with resistance to fluoroquinolones. This report contributes to the growing literature regarding P. mendocina-related infections.

A Case of Pseudomonas mendocina Bacteremia in an Elderly Man With Bilateral Leg Lesions

Pseudomonas mendocina is a gram-negative, aerobic, rod-shaped bacterium that rarely causes disease in humans. Documented infections can be severe with varying etiologies, often requiring intensive care. We describe a rare case of bacteremia with P. mendocina in an elderly male, with a comprehensive review of the literature.

An 81-year-old Caucasian male presented with bilateral lower leg erythema and drainage but was afebrile. His past medical history included atrial fibrillation, chronic kidney disease, and congestive heart failure. Labs showed leukocytosis and a blood culture was obtained revealing Pseudomonas mendocina. The pathogen was susceptible to all antibiotics tested and he was successfully treated on cefepime inpatient and a two-week course of ciprofloxacin on discharge.

Our case and literature review presents a successful treatment of a rare cause of bacteremia likely stemming from a soft tissue nidus. P. mendocina has a favorable susceptibility profile and the antibiotics preferred differ from Pseudomonas aeruginosa, a more common pathogen. Worldwide there have been only 18 other documented cases of P. mendocina infection, all successful and with no mortality. Physicians can confidently utilize usual antibiotics in the treatment of this pathogen despite its rare clinical manifestations.

Soul of the Jukskei River: The Extent of Bacterial Contamination in the Jukskei River in Gauteng Province, South Africa

River water quality is an important health issue as the water is utilised for drinking, domestic and agricultural use in developing countries. This study aimed to investigate the effect water from a major city has on the water quality of the Jukskei River that daylights in Johannesburg, South Africa. The river water samples were analysed for physio-chemical properties, microbiology, antibiotic resistance of bacterial isolates, genetic markers, and potentially toxic metals. Data analysis revealed increased electrical conductivity, total dissolved solids, and turbidity since 2010. Total Coliform and Escherichia coli detected were above the South African water quality guidelines for domestic, recreational, and irrigation purposes. Additionally, sodium, zinc, nickel, lithium, and lead exceeded the guidelines in domestic, recreational, and irrigation water. Pathogenic strains of E. coli (aEPEC, EHEC, EIEC, and EAEC) were isolated from the water. Various other potentially pathogenic organisms that have been implicated as causes of gastro-intestinal, and a wide range of other diseases, were also detected and demonstrated multiple levels of resistance to antibiotics tested. The results show that the river water is a potential health threat to downstream users. These results will feed into the environmental management action plan for Water for the Future (NGO group).

Pseudomonas Mendocina Bacteremia in a Hemodialysis Patient With a Central Venous Catheter

Pseudomonas mendocina is an uncommon pathogen in humans and there are no documented cases of infection associated with central venous catheters. Here we describe a 72-year-old man on hemodialysis who presented with a fever and was found to have P. mendocina bacteremia. The only obvious source of infection was the hemodialysis catheter. The isolate was susceptible to all antibiotics tested and he was successfully treated with ciprofloxacin and central venous catheter removal. Patients with chronic medical conditions and vascular devices are at risk for invasive infections with rare Pseudomonas species. As laboratory pathogen detection advances arise, it is possible that additional cases of Pseudomonas mendocina infections in humans will be identified. Our case provides one example of the successful treatment of Pseudomonas mendocina bacteremia in a 72-year-old man with a line-associated infection.

Re-identification of strains deposited as Pseudomonas aeruginosa, Pseudomonas fluorescens and Pseudomonas putida in GenBank based on whole genome sequences

The taxonomic classification of Pseudomonas species has been revised and updated several times. This study utilized average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) cutoff values of 95 and 70 %, respectively, to re-identify the species of strains deposited in GenBank as P. aeruginosa, P. fluorescens and P. putida. Of the 264 deposited P. aeruginosa strains, 259 were correctly identified as P. aeruginosa, but the remaining five were not. All 28 deposited P. fluorescens strains had been incorrectly identified as P. fluorescens. Four of these strains were re-identified, including two as P. kilonensis and one each as P. aeruginosa and P. brassicacearum, but the remaining 24 could not be re-identified. Similarly, all 35 deposited P. putida strains had been incorrectly identified as P. putida. Nineteen of these strains were re-identified, including 12 as P. alloputida, four as P. asiatica and one each as P. juntendi, P. monteilii and P. mosselii. These results strongly suggest that Pseudomonas bacteria should be identified using ANI and dDDH analyses based on whole genome sequencing when Pseudomonas species are initially deposited in GenBank/DDBJ/EMBL databases.

A Systematic Review of Human Infections by Pseudomonas mendocina

Pseudomonas mendocina is a Gram-negative, rod-shaped, aerobic bacterium that belongs in the family Pseudomonadaceae and has been isolated from water and soil. Even though it is thought to cause infections quite rarely in humans, it can cause severe infections even in immunocompetent individuals. The aim of this study was to systemically review all cases of human infection by P. mendocina in the literature and describe their epidemiology, microbiology, antimicrobial susceptibility, treatment and outcomes. Thus, a systematic review of PubMed for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of Pseudomonas mendocina infections was conducted. In total, 12 studies, containing data of 16 patients, were included. The commonest P. mendocina infections were infective endocarditis, central nervous system infections and skin and soft tissue infections (SSTIs). Fever was the main presenting symptom, while sepsis was evident in almost half the patients. Pseudomonas mendocina was susceptible to most antibiotics tested. Mortality was low in all different infection types. Third or fourth generation cephalosporins and quinolones are the commonest agents used for treatment, irrespectively of the infection site.

A Genome Model to Explain Major Features of Neurodevelopmental Disorders in Newborns

The purpose of this study was to test the hypothesis that infections are linked to chromosomal anomalies that cause neurodevelopmental disorders. In children with disorders in the development of their nervous systems, chromosome anomalies known to cause these disorders were compared with foreign DNAs, including known teratogens. Genes essential for neurons, lymphatic drainage, immunity, circulation, angiogenesis, cell barriers, structure, epigenetic and chromatin modifications were all found close together in polyfunctional clusters that were deleted or rearranged in neurodevelopmental disorders. In some patients, epigenetic driver mutations also changed access to large chromosome segments. These changes account for immune, circulatory, and structural deficits that accompany neurologic deficits. Specific and repetitive human DNA encompassing large deletions matched infections and passed rigorous artifact tests. Deletions of up to millions of bases accompanied infection-matching sequences and caused massive changes in human homologies to foreign DNAs. In data from 3 independent studies of private, familial, and recurrent chromosomal rearrangements, massive changes in homologous microbiomes were found and may drive rearrangements and encourage pathogens. At least 1 chromosomal anomaly was found to consist of human DNA fragments with a gap that corresponded to a piece of integrated foreign DNA. Microbial DNAs that match repetitive or specific human DNA segments are thus proposed to interfere with the epigenome and highly active recombination during meiosis, driven by massive changes in human DNA-foreign DNA homologies. Abnormal recombination in gametes produces zygotes containing rare chromosome anomalies that cause neurologic disorders and nonneurologic signs. Neurodevelopmental disorders may be examples of assault on the human genome by foreign DNAs at a critical stage. Some infections may be more likely tolerated because they resemble human DNA segments. Even rare developmental disorders can be screened for homology to infections within altered epigenomes and chromatin structures. Considering effects of foreign DNAs can assist prenatal and genetic counseling, diagnosis, prevention, and early intervention.

The clinical characteristics of spontaneous Gram-negative bacterial meningitis in adults: A hospital-based study

The epidemiologic trend of acute bacterial meningitis can change more dramatically than any other bacterial disease, and a decrease in spontaneous adult bacterial meningitis (ABM) has been noted in serial studies of the epidemiologic trend of ABM in Taiwan. The purpose of this study was to analyze the clinical characteristics, laboratory data and therapeutic outcomes of 149 patients with spontaneous Gram-negative (G(-)) ABM collected during a study period of 31 years (1986-2016). The 149 patients included 107 men and 42 women, aged 18-86 years. The common underlying conditions were diabetes mellitus, liver cirrhosis and alcoholism, and the leading clinical presentations were fever, altered consciousness and septic shock. Compared the clinical characteristics of the patients identified in the study period of 2001-2106 to the patients identified in the study period of 1986-2000, the former group of patients had a significantly higher incidence of systemic malignance. In the recent 16 years (2001-2016), Klebsiella pneumoniae, Pseudomonas spp. and Escherichia coli were the leading three implicated bacterial pathogens of spontaneous G(-) ABM, accounting for 61.3% (38/62), 11.3% (7/62) and 11.3% (7/62%) of all cases, respectively. The overall mortality rate from spontaneous G(-) ABM was high (47.0%, 70/149) and the presence of septic shock and lower cerebrospinal fluid glucose level were significant prognostic factors. Because of the decreasing incidence of spontaneous ABM in Taiwan, close examination of this specific infectious syndrome is important in order to monitor the epidemiologic trend and improve the therapeutic strategy.

Pseudomonas Mendocina Bacteremia: A Case Study and Review of Literature

Patient: Male, 64

Final Diagnosis: Pseudomonas mendocina bacteremia

Symptoms: Encephalopathy • fever • hypotension • rigors • tachypnea

Medication: —

Clinical Procedure: —

Specialty: Infectious Diseases