Opportunistic Infections Research Articles

The inhibition mechanism of co-cultured probiotics on biofilm formation of Klebsiella pneumoniae.

Klebsiella pneumoniae, an important opportunistic pathogen of nosocomial inflection, is known for its ability to form biofilm. The purpose of the current study is to assess how co- or mono-cultured probiotics affect K. pneumoniae's ability to produce biofilms and investigate the potential mechanisms by using a polyester nonwoven chemostat and a Caco-2 cell line. Compared with pure cultures of Lactobacillus rhamnosus and Lactobacillus sake, the formation of K. pneumoniae biofilm was remarkably inhibited by the mixture of L. rhamnosus, L. sake, and Bacillus subtilis at a ratio of 5:5:1 by means of qPCR and FISH assays. In addition, Lactobacillus in combination with B. subtilis could considerably reduce the adherence of K. pneumoniae to Caco-2 cells by using inhibition, competition, and displacement assays. According to the RT-PCR assay, the adsorption of K. pneumoniae to Caco-2 cells was effectively inhibited by the co-cultured probiotics, leading to significant reduction in the expression of proinflammatory cytokines induced by K. pneumoniae. Furthermore, the HPLC and RT-PCR analyses showed that the co-cultured probiotics were able to successfully prevent the expression of the biofilm-related genes of K. pneumoniae by secreting plenty of organic acids as well as the second signal molecule (c-di-GMP), resulting in inhibition on biofilm formation. Co-culture of L. sake, L. rhamnosus, and B. subtilis at a ratio of 5:5:1 could exert an antagonistic effect on the colonization of pathogenic K. pneumoniae by down-regulating the expression of biofilm-related genes. At the same time, the co-cultured probiotics could effectively inhibit the adhesion of K. pneumoniae to Caco-2 cells and block the expression of proinflammatory cytokines induced by K. pneumoniae.

Irrigation Scheduling Impacts Vegetative Growth, Seed Yield, and Fungal Diseases of Spinach Seed Crops in a Maritime Mediterranean Climate

Although irrigation scheduling has been studied for diverse vegetable crops, much less attention has been given to irrigation scheduling for the seed crops on which these production systems rely. In spinach, for which irrigation scheduling needs are likely to vary greatly between seed and leaf production, this leaves seed producers without adequate resources to make irrigation scheduling decisions. Our research sought to fill this gap by evaluating two alternative irrigation scheduling strategies (a publicly available decision-support tool and soil moisture sensors) and four soil moisture thresholds for irrigation for their impacts on vegetative growth, marketable seed yield, seed quality, and the severity of Stemphylium leaf spot (caused by Stemphylium vesicarium and Stemphylium beticola), a common foliar disease of spinach, under sprinkler irrigation. We found that in all 3 years of the study, earlier and more frequent irrigation increased vegetative growth. However, marketable seed yield only increased relative to the control treatment based on farmers’ standard irrigation practices in 1 of the 3 years—a year with an abnormally late planting date. This indicates that vegetative growth is more responsive than seed yield to earlier and more frequent irrigation, and that increases in vegetative growth do not translate directly to increased marketable seed yield. Contrary to the expected increase in Stemphylium leaf spot severity with increasing irrigation, the severity decreased in both years it was measured, likely as a result of the small stature of the spinach seed parent lines used in our study and opportunistic pathogenicity on moisture-stressed plants. These results provide a useful foundation from which spinach seed producers can make irrigation management decisions for their crops that underpin a valuable global industry.

Distinct Escherichia coli transcriptional profiles in the guts of recurrent UTI sufferers revealed by pangenome hybrid selection.

Low-abundance members of microbial communities are difficult to study in their native habitats. This includes Escherichia coli, a minor, but common inhabitant of the gastrointestinal tract and opportunistic pathogen, including of the urinary tract, where it is the primary pathogen. While multi-omic analyses have detailed critical interactions between uropathogenic Escherichia coli (UPEC) and the bladder that mediate UTI outcome, comparatively little is known about UPEC in its pre-infection reservoir, partly due to its low abundance there (<1% relative abundance). To accurately and sensitively explore the genomes and transcriptomes of diverse E. coli in gastrointestinal communities, we developed E. coli PanSelect which uses a set of probes designed to specifically recognize and capture E. coli's broad pangenome from sequencing libraries. We demonstrated the ability of E. coli PanSelect to enrich, by orders of magnitude, sequencing data from diverse E. coli using a mock community and a set of human stool samples collected as part of a cohort study investigating drivers of recurrent urinary tract infections (rUTI). Comparisons of genomes and transcriptomes between E. coli residing in the gastrointestinal tracts of women with and without a history of rUTI suggest that rUTI gut E. coli are responding to increased levels of oxygen and nitrate, suggestive of mucosal inflammation, which may have implications for recurrent disease. E. coli PanSelect is well suited for investigations of native in vivo biology of E. coli in other environments where it is at low relative abundance, and the framework described here has broad applicability to other highly diverse, low abundance organisms.

Multiple Myeloma: A Review of the Literature and a Case Report Highlighting the Immunocompromised State of Myeloma Patients.

Multiple myeloma (MM), a malignancy involving plasma cells, disproportionately affects older adults with an average age of diagnosis of about 70 years. Oftentimes, the therapies used in the treatment of MM are associated with a risk for immunotoxicity, lowering the ability of the immune system to fight off opportunistic infections. This is an important relationship for clinicians to realize as the incidence of opportunistic infections in myeloma patients is increasing. As an example, we present a case of a patient with MM who subsequently developed a cryptococcal infection. Our paper will highlight the key details of the case as well as shed light on the importance of understanding the immunodeficiencies in this patient population. We highlight important aspects of the current literature related to MM and relate them to the associated case.

Development of biopolymer films loaded with fluconazole and thymol for resistant vaginal candidiasis

Vulvovaginal candidiasis (VVC) is an opportunistic infection caused by a fungus of the Candida genus, affecting approximately 75 % of women during their lifetime. Fungal resistance cases and adverse effects have been the main challenges of oral therapies. In this study, the topical application of thin films containing fluconazole (FLU) and thymol (THY) was proposed to overcome these problems. Vaginal films based only on chitosan (CH) or combining this biopolymer with pectin (PEC) or hydroxypropylmethylcellulose acetate succinate (HPMCAS) were developed by the solvent casting method. In addition to a higher swelling index, CH/HPMCAS films showed to be more plastic and flexible than systems prepared with CH/PEC or only chitosan. Biopolymers and FLU were found in an amorphous state, contributing to explaining the rapid gel formation after contact with vaginal fluid. High permeability rates of FLU were also found after its immobilization into thin films. The presence of THY in polymer films increased the distribution of FLU in vaginal tissues and resulted in improved anti-Candida activity. A significant activity against the resistant C. glabrata was achieved, reducing the required FLU dose by 50 %. These results suggest that the developed polymer films represent a promising alternative for the treatment of resistant vulvovaginal candidiasis, encouraging further studies in this context.

Two-year evaluation of Legionella in an aging residential building: Assessment of multiple potable water remediation approaches

Legionella is an opportunistic waterborne pathogen that is difficult to eradicate in colonized drinking water pipes. Legionella control is further challenged by aging water infrastructure and lack of evidence-based guidance for building treatment. This study assessed multiple premise water remediation approaches designed to reduce Legionella pneumophila within a residential building located in an aging, urban drinking water system over a two-year period. Samples (n = 745) were collected from hot and cold-water lines and quantified via most probable number culture. Building-level treatment approaches included three single heat shocks, three single chemical shocks, and continuous low-level chemical disinfection in the potable water system. The building was highly colonized with L. pneumophila with 71 % L. pneumophila positivity. Single heat shocks had a statistically significant L. pneumophila reduction one day post treatment but no significant L. pneumophila reduction at one week, two weeks, and four weeks post treatment. The first two chemical shocks resulted in statistically significant L. pneumophila reduction at two days and four weeks post treatment, but there was a significant L. pneumophila increase at four weeks following the third chemical shock. Continuous low-level chemical disinfection resulted in statistically significant L. pneumophila reduction at ten weeks post treatment implementation. This demonstrates that in a building highly colonized with L. pneumophila, sustained remediation is best achieved using continuous low-level chemical treatment.

Preclinical development of ATR04-484, an auxotrophic strain of Staphylococcus epidermidis, for the topical treatment of epidermal growth factor receptor (EGFR) inhibitor-induced dermal toxicity.

e24074 Background: Agents targeting the EGFR-mediated signaling pathway are commonly used for the treatment of advanced lung, pancreatic, colorectal, and head and neck cancers. Significant dermal toxicities, which occur in up to 90% of patients treated with EGFR inhibitors (EGFRis) and other therapies inhibiting downstream signaling pathways, may be disruptive to a patient’s quality of life and adherence to therapy. Inhibition of the EGFR pathway may suppress host defenses and lead to opportunistic pathogenic colonization or infection. EGFRi-induced dermal toxicity is associated with elevated levels of Staphylococcus aureus and IL-36γ. ATR04-484 is a topical ointment containing S. epidermidis strain SE484, isolated from a healthy human volunteer that was selected for its ability to inhibit S. aureus and IL-36γ . Methods: Reconstructed human epidermis (RHE) and ex vivo pig skin were used to measure the effect of ATR04-484 on S. aureus in therapeutic and prophylactic settings with S. aureus added prior to or after ATR04-484, respectively. To evaluate the anti-inflammatory effects of ATR04-484, IL-36γ levels were measured on untreated RHE and RHE treated with erlotinib alone or in combination with ATR04-484. 104 colony-forming units (CFU) of methicillin-resistant (MRSA) or methicillin-sensitive (MSSA) S. aureus were used. Toxicology was assessed by measuring cell viability in three in vitro toxicology assays: the eye irritant potential was tested on 3D reconstituted human cornea-like epithelium (RhCE), the skin irritant potential of the strain in the ointment was assessed on 3D RHE, and the skin corrosive potential was evaluated on RHE. Results: ATR04-484 comparably inhibited growth of both MRSA and MSSA in therapeutic and prophylactic settings. In a therapeutic setting, ATR04-484 inhibited MRSA growth by 1 log (90%) compared to untreated MRSA in both RHE and pig skin. In a prophylactic setting, ATR04-484 inhibited MRSA growth by approximately 5 logs on RHE and 2 logs on pig skin. Additionally, application of ATR04-484 reduced IL-36γ to a level comparable to untreated RHE. The effect was dose-dependent; application of 109CFU/cm2 of ATR04-484 showed more potent IL-36γ reduction compared to 108 CFU/cm2. The three toxicology assays indicate that ATR04-484 does not cause irritation or corrosion. Conclusions: In these preclinical studies, ATR-04-484 showed a promising preclinical profile for the treatment of EGFRi-induced dermal toxicity by significantly reducing S. aureus growth, completely ameliorating IL-36γ levels, and showing no safety concerns.

Pulmonary coinfection by Pneumocystis jirovecii and Aspergillus terreus in an ITP patient after corticosteroid therapy: A case report

AbstractPneumocystis jirovecii pneumonia and invasive pulmonary aspergillosis are both life‐threatening opportunistic fungal infections. There are only few reports of coinfection by these two fungi in the literature, and Aspergillus fumigatus is the predominant Aspergillus species in the coinfection. We report here the first case of coinfection by Aspergillus terreus and P. jirovecii pneumonia and caspofungin can be an appropriate choice for salvage treatment of the coinfection. A 51‐year‐old man with a history of immune thrombocytopenia treated with prednisone over 2 months was admitted to emergency intensive care unit for acute respiratory failure and a cavity was found on chest computed tomography. Therefore, his trachea was immediately intubated. The patient was treated with a large spectrum of antibiotic regimen, consisting initially of imipenem/cilastatin, moxifloxacin and fluconazole followed by fluconazole, imipenem/cilastatin, vancomycin, trimethoprim–sulphamethoxazole (TMP‐SMZ) and azithromycin. When the polymerase chain reaction analysis of the bronchoalveolar lavage sample revealed P. jirovecii and A. terreus, all the antibiotics were stopped except TMP‐SMZ, and voriconazole was added. Two weeks later, the patient showed clinical improvement but radiological deterioration. Consequently, caspofungin was started for salvage therapy, then the patient showed gradual clinical improvement. He was discharged with oral voriconazole and TMP‐SMZ. The antifungal treatment was continued for 6 months until complete radiological absorption. In conclusion, early bronchoscopy with bronchoalveolar lavage fluid should be considered in order to diagnose and treat promptly in those treated with corticosteroids combined with immunocompromised and caspofungin could be an appropriate choice for salvage treatment of coinfection by P. jirovecii and A. terreus.

Impact of secreted glucanases upon the cell surface and fitness of Candida albicans during colonisation and infection

Host recognition of the pathogen-associated molecular pattern (PAMP), β-1,3-glucan, plays a major role in antifungal immunity. β-1,3-glucan is an essential component of the inner cell wall of the opportunistic pathogen Candida albicans. Most β-1,3-glucan is shielded by the outer cell wall layer of mannan fibrils, but some can become exposed at the cell surface. In response to host signals such as lactate, C. albicans shaves the exposed β-1,3-glucan from its cell surface, thereby reducing the ability of innate immune cells to recognise and kill the fungus. We have used sets of barcoded xog1 and eng1 mutants to compare the impacts of the secreted β-glucanases Xog1 and Eng1 upon C. albicans in vitro and in vivo. Flow cytometry of Fc-dectin-1-stained strains revealed that Eng1 plays the greater role in lactate-induced β-1,3-glucan masking. Transmission electron microscopy and stress assays showed that neither Eng1 nor Xog1 are essential for cell wall maintenance, but the inactivation of either enzyme compromised fungal adhesion to gut and vaginal epithelial cells. Competitive barcode sequencing suggested that neither Eng1 nor Xog1 strongly influence C. albicans fitness during systemic infection or vaginal colonisation in mice. However, the deletion of XOG1 enhanced C. albicans fitness during gut colonisation. We conclude that both Eng1 and Xog1 exert subtle effects on the C. albicans cell surface that influence fungal adhesion to host cells and that affect fungal colonisation in certain host niches.

Tsukamurella Bacteremia in a Surgical Patient: Case Report and Review of the Literature.

Background: Tsukamurella species were first isolated in 1941. Since then, 48 cases of Tsukamurella bacteremia have been reported, a majority of which were immunosuppressed patients with central venous catheters.A case is described and previous cases of Tsukamurella bacteremia are reviewed. Patients and Methods: A 70-year-old total parenteral nutrition (TPN)-dependent female with recurrent enterocutaneous fistula (ECF), developed leukocytosis one week after a challenging ECF takedown. After starting broad-spectrum antibiotic agents, undergoing percutaneous drainage of intra-abdominal abscess, and subsequent repositioning of the drain, her leukocytosis resolved. Blood and peripherally inserted central catheter (PICC) cultures grew Tsukamurella spp. The patient was discharged to home with 14 days of daily 2 g ceftriaxone, with resolution of bacteremia. Conclusions: Tsukamurella spp. are a rare opportunistic pathogen predominantly affecting immunocompromised patients, with central venous catheters present in most cases. However, there have been few reported cases in immunocompetent individuals with predisposing conditions such as end-stage renal disease and uncontrolled diabetes mellitus.

Advances in Mechanism of HIV-1 Immune Reconstitution Failure: Understanding Lymphocyte Subpopulations and Interventions for Immunological Nonresponders.

In individuals diagnosed with AIDS, the primary method of sustained suppression of HIV-1 replication is antiretroviral therapy, which systematically increases CD4+ T cell levels and restores immune function. However, there is still a subset of 10-40% of people living with HIV who not only fail to reach normal CD4+ T cell counts but also experience severe immune dysfunction. These individuals are referred to as immunological nonresponders (INRs). INRs have a higher susceptibility to opportunistic infections and non-AIDS-related illnesses, resulting in increased morbidity and mortality rates. Therefore, it is crucial to gain new insights into the primary mechanisms of immune reconstitution failure to enable early and effective treatment for individuals at risk. This review provides an overview of the dynamics of key lymphocyte subpopulations, the main molecular mechanisms of INRs, clinical diagnosis, and intervention strategies during immune reconstitution failure, primarily from a multiomics perspective.

Antibiotic resistance pattern of waterborne causative agents of healthcare-associated infections: A call for biofilm control in hospital water systems

BackgroundIn recent years, the global spread of antimicrobial resistance has become a concerning issue, often referred to as a “silent pandemic”. Healthcare-associated infections (HAIs) caused by antibiotic-resistant bacteria (ARB) are a recurring problem, with some originating from waterborne route. The study aimed to investigate the presence of clinically relevant opportunistic bacteria and antibiotic resistance genes (ARGs) in hospital water distribution systems (WDSs). MethodsWater and biofilm samples (n = 192) were collected from nine hospitals in Isfahan and Kashan, located in central Iran, between May 2022 and June 2023. The samples were analyzed to determine the presence and quantities of opportunistic bacteria and ARGs using cultural and molecular methods. ResultsStaphylococcus spp. were highly detected in WDS samples (90 isolates), with 33 % of them harboring mecA gene. However, the occurrences of E. coli (1 isolate), Acinetobacter baumannii (3 isolates), and Pseudomonas aeruginosa (14 isolates) were low. Moreover, several Gram-negative bacteria containing ARGs were identified in the samples, mainly belonging to Stenotrophomonas, Sphingomonas and Brevundimonas genera. Various ARGs, as well as intI1, were found in hospital WDSs (ranging from 14 % to 60 %), with higher occurrences in the biofilm samples. ConclusionOur results underscore the importance of biofilms in water taps as hotspots for the dissemination of opportunistic bacteria and ARG within hospital environments. The identification of multiple opportunistic bacteria and ARGs raises concerns about the potential exposure and acquisition of HAIs, emphasizing the need for proactive measures, particularly in controlling biofilms, to mitigate infection risks in healthcare settings.

Investigation of high-risk antibiotic resistance bacteria and their associated antibiotic resistance genes in different agricultural soils with biogas slurry from China

High-risk antibiotic-resistant bacteria (ARB) and their accompanying antibiotic resistance genes (ARGs) seriously threaten public health. As a crucial medium for ARB and ARGs spread, soils with biogas slurry have been widely investigated. However, few studies focused on high-risk multi-drug resistant bacteria (MDRB) and their associated ARGs. This study examined ARB distribution in different agricultural soils with biogas slurry across 12 districts in China. It identified high-risk MDRB in various soil backgrounds, elucidating their resistance and spread mechanism. The findings revealed that diverse cultured ARB were enriched in soils with biogas slurry, especially soil ciprofloxacin ARB, which were enriched (>2.5 times) in 68.4 % of sampling sites. Four high-risk MDRB isolated from Hebei, Zhejiang, Shanxi, and Gansu districts were identified as severe or opportunistic pathogens, which carried abundant mobile genetic elements (MGEs) and 14 known high risk ARGs, including aac(3)-IId, aac(6')-Ib3, aph(6)-Id, aac(6')-Ib3, aadA1, blaOXA-10, blaTEM-1B, dfrA12, dfrA14, cmlA1, sul1, floR, tet(M) and tet(L). The antibiotics accumulation, diverse ARGs and MGEs enrichment, and proliferation of pathogenic bacteria could be potential driving factors of their occurrence and spread. Therefore, the coexistence of the high-risk MDRB and ARGs combined with the associated MGEs in soils with biogas slurry should be further investigated to develop technology and policy for reducing their negative influences on the effectiveness of clinical antibiotics.

Exploring roles of the chitinase ChiC in modulating Pseudomonas aeruginosa virulence phenotypes.

Chitinases are ubiquitous enzymes involved in biomass degradation and chitin turnover in nature. Pseudomonas aeruginosa (PA), an opportunistic human pathogen, expresses ChiC, a secreted glycoside hydrolase 18 family chitinase. Despite speculation about ChiC's role in PA disease pathogenesis, there is scant evidence supporting this hypothesis. Since PA cannot catabolize chitin, we investigated the potential function(s) of ChiC in PA pathophysiology. Our findings show that ChiC exhibits activity against both insoluble (α- and β-chitin) and soluble chitooligosaccharides. Enzyme kinetics toward (GlcNAc)4 revealed a kcat of 6.50 s-1 and a KM of 1.38 mM, the latter remarkably high for a canonical chitinase. In our label-free proteomics investigation, ChiC was among the most abundant proteins in the Pel biofilm, suggesting a potential contribution to PA biofilm formation. Using an intratracheal challenge model of PA pneumonia, the chiC::ISphoA/hah transposon insertion mutant paradoxically showed slightly increased virulence compared to the wild-type parent strain. Our results indicate that ChiC is a genuine chitinase that contributes to a PA pathoadaptive pathway.IMPORTANCEIn addition to performing chitin degradation, chitinases from the glycoside hydrolase 18 family have been found to play important roles during pathogenic bacterial infection. Pseudomonas aeruginosa is an opportunistic pathogen capable of causing pneumonia in immunocompromised individuals. Despite not being able to grow on chitin, the bacterium produces a chitinase (ChiC) with hitherto unknown function. This study describes an in-depth characterization of ChiC, focusing on its potential contribution to the bacterium's disease-causing ability. We demonstrate that ChiC can degrade both polymeric chitin and chitooligosaccharides, and proteomic analysis of Pseudomonas aeruginosa biofilm revealed an abundance of ChiC, hinting at a potential role in biofilm formation. Surprisingly, a mutant strain incapable of ChiC production showed higher virulence than the wild-type strain. While ChiC appears to be a genuine chitinase, further investigation is required to fully elucidate its contribution to Pseudomonas aeruginosa virulence, an important task given the evident health risk posed by this bacterium.

Botanical Control of Multiple Drug Resistant Pseudomonas aeruginosa infection in Clarias gariepinus

Pseudomonas aeruginosa is a Gram-negative, rod-shaped bacterium which can cause opportunistic infections in fishes. Ethanolic leaf extract of Moringa oleifera was used in the treatment of Pseudomonas aeruginosa infected Clarias gariepinus for a period of 10 days. Pathogen-free Clarias gariepinus fingerlings (n=120) were randomly distributed into four different groups (A-D). Group A, Infected Clarias gariepinus without treatment; group B, Infected Clarias gariepinus treated with ciprofloxacin 250 mg/mL); group C, Infected Clarias gariepinus treated with 500 mg/L Moringa oleifera extract; and group D, Infected Clarias gariepinus treated with 1500 mg/L Moringa oleifera extract. A 0.1 mL aliquot of 7.2×105 CFU/mL of Pseudomonas aeruginosa culture was intra-peritoneally injected into the body of the fingerlings to induce infection. The gill of fish was excised, homogenized and centrifuged to ascertain oxidative stress, while histological examination followed thereafter. The minimum inhibitory concentration of the ethanol extract was 125 mg/mL while the minimum bactericidal concentration was at 500 mg/mL. Gross morphology examination showed hemorrhage in the gill and mouth, and swollen abdomen, after 72 h of infection. The weight of Pseudomonas aeruginosa infected Clarias gariepinus before and after treatment showed no significant differences (P &gt; 0.05) among the groups. There was significant (p&lt;0.05) reduction in oxidative stress parameters examined. Histopathological changes noticed were minor hemorrhage epitheliocystis and damaged gill lamella. Total bacterial count showed a reduction in the Pseudomonas load in groups C and D over the period of study thus, indicating strong potentials of Moringa oleifera in the control of fish Pseudomonas infection.

Distribution of sequence types and antimicrobial resistance of clinical Pseudomonas aeruginosa isolates from dogs and cats visiting a veterinary teaching hospital in Thailand

BackgroundPseudomonas aeruginosa is an important opportunistic pathogen in dogs and cats and is resistant to several antimicrobial drugs; however, data on the clonal distribution of P. aeruginosa in veterinary hospital are limited. This study aimed to investigate the clonal dissemination and antimicrobial resistance of clinical P. aeruginosa in a veterinary teaching hospital in Thailand within a 1-year period. Minimum inhibitory concentration determination and whole genome sequencing were used for antimicrobial susceptibility analysis and genetic determination, respectively.ResultsForty-nine P. aeruginosa were isolated mostly from the skin, urinary tract, and ear canal of 39 dogs and 10 cats. These isolates belonged to 39 sequence types (STs) that included 9 strains of high-risk clones of ST235 (n = 2), ST244 (n = 2), ST274 (n = 2), ST277 (n = 1), ST308 (n = 1), and ST357 (n = 1). Overall antimicrobial resistance rate was low (< 25%), and no colistin-resistant strains were found. Two carbapenem-resistant strains belonging to ST235 and ST3405 were identified.ConclusionsClinical P. aeruginosa in dogs and cats represent STs diversity. High-risk clones and carbapenem-resistant strains are a public health concern. Nevertheless, this study was limited by a small number of isolates. Continuous monitoring is needed, particularly in large-scale settings with high numbers of P. aeruginosa, to restrict bacterial transfer from companion animal to humans in a veterinary hospital.

Type-2 diabetes mellitus enhances Klebsiella pneumoniae pathogenesis.

Klebsiella pneumoniae is an opportunistic pathogen and an important cause of pneumonia, bacteremia, and urinary tract infection. K. pneumoniae infections are historically associated with diabetes mellitus. There is a fundamental gap in our understanding of how diabetes mellitus, specifically type 2 diabetes, influences K. pneumoniae pathogenesis. K. pneumoniae pathogenesis is a multifactorial process that often begins with gut colonization, followed by an escape from the gut to peripheral sites, leading to host damage and infection. We hypothesized that type 2 diabetes enhances K. pneumoniae pathogenesis. To test this, we used well-established mouse models of K. pneumoniae colonization and lung infection in conjunction with a mouse model of spontaneous type 2 diabetes mellitus (T2DM). We show that T2DM enhances susceptibility to both K. pneumoniae colonization and infection. The enhancement of gut colonization is dependent on T2DM-induced modulation of the gut microbiota community structure. In contrast, lung infection is exacerbated by the increased availability of amino acids in the lung, which is associated with higher levels of vascular endothelial growth factor. These data lay the foundation for mechanistic interrogation of the relationship between K. pneumoniae pathogenesis and type 2 diabetes mellitus, and explicitly establish T2DM as a risk factor for K. pneumoniae disease.

Co-occurrence of the cephalosporinase cepA and carbapenemase cfiA genes in a Bacteroides fragilis division II strain, an unexpected finding.

Bacteroides fragilis, an anaerobic gut bacterium and opportunistic pathogen, comprises two genetically divergent groups (or divisions) at the species level. Differences exist both in the core and accessory genomes and the beta-lactamase genes, with the cephalosporinase gene cepA represented only in division I and the carbapenemase gene cfiA only in division II. Multidrug resistance in a clinical B. fragilis strain was examined by whole-genome sequencing. Strain CNM20200260 carried the antimicrobial resistance genes cepA, cfiA2, ant(6'), erm(F), mef(En2), est(T), tet(Q) and cat(A), along with 82-Phe mutation in gyrA (together with 47 amino acid changes in gyrA/B and parC/parE). bexA/B and other efflux pump genes were also observed. None of the detected insertion sequences was located upstream of cfiA2. The genome-based taxonomy coefficients (average nucleotide identity, DNA-DNA hybridization similarity and difference in genomic G + C%) with respect to genomes of the strains of B. fragilis division II and the novel species Bacteroides hominis (both cfiA-positive) met the criteria for CNM20200260 to belong to either species (>95%, >70% and <1%, respectively). No such similarity was seen with type strain NCTC 9343 or the representative genome FDAARGOS 1225 of B. fragilis (division I, cfiA-negative). Strain CNM20200260 harboured four out of nine Kyoto Encyclopedia of Genes and Genomes orthologues defined for division I and one of two defined for division II. This is the first description of the co-occurrence of cepA and cfiA in a Bacteroides strain, confirming the complexity of the taxonomy of this species.

Clinical risk factors and outcomes of carbapenem-resistant Escherichia coli nosocomial infections in a Chinese teaching hospital: a retrospective study from 2013 to 2020.

The emergence of carbapenem-resistant Escherichia coli strains poses a considerable challenge to global public health, and little is known about carbapenemase-producing E. coli strains in Tianjin, China. This study aimed to investigate the risk factors for infections with carbapenem-resistant E. coli (CREC) strains. This retrospective case-control study was conducted at a tertiary teaching hospital. A total of 134 CREC clinical isolates were collected from the General Hospital of Tianjin Medical University between 2013 and 2020. The control group was selected at a ratio of 1:1 from patients with nosocomial carbapenem-susceptible E. coli infection. Risk factors for nosocomial CREC infection and clinical outcomes were analyzed using univariate and multivariate analyses. Multivariate analysis revealed that cephalosporin exposure (odd ratio OR = 2.01), carbapenem exposure (OR = 1.96), glucocorticoid exposure (OR = 32.45), and surgical history (OR = 3.26) were independent risk factors for CREC infection. The in-hospital mortality rate in the CREC group was 29.1%, and age >65 years (OR = 3.19), carbapenem exposure (OR = 3.54), and central venous catheter insertion (OR = 4.19) were independent risk factors for in-hospital mortality in patients with CREC infections. Several factors were identified in the development of nosocomial CREC infections. The CREC isolates were resistant to most antibiotics. Reducing CREC mortality requires a comprehensive consideration of appropriate antibiotic use, underlying diseases, and invasive procedures.IMPORTANCEEscherichia coli is an opportunistic pathogen that causes severe hospital-acquired infections. The spread of carbapenem-resistant E. coli is a global threat to public health, and only a few antibiotics are effective against these infections. Consequently, these infections are usually associated with poor prognosis and high mortality. Therefore, understanding the risk factors associated with the causes and outcomes of these infections is crucial to reduce their incidence and initiate appropriate therapies. In our study, several factors were found to be involved in nosocomial carbapenem-resistant E. coli (CREC) infections, and CREC isolates were resistant to most antibiotics. Reducing CREC mortality needs a comprehensive consideration of whether antibiotics are used appropriately, underlying diseases, and invasive interventions. These findings provide valuable evidence for the development of anti-infective therapy, infection prevention, and control of CREC-positive infections.

Antibacterial Potential of Ethanolic Extract of Avocado Leaves (Persea americana mill.) against Clinical Isolate of Klebsiella pneumoniae and Proteus mirabilis

Multidrug resistance is a global health problem that is closely related to microbial resistance. Klebsiella pneumonia and Proteus mirabilis are opportunistic bacteria that cause urinary tract infections, especially in the use of catheters in hospitals in inpatient care. Handling it using commercial antibiotics can increase the effect of antibacterial resistance if the use is irrational and neglected. Avocado leaves have been reported to have antibacterial, antidiabetic and antioxidant activity. The purpose of this study was to observe into the antibacterial activity of avocado leaves ethanol extract against K. pneumoniae and P. mirabilis. The minimum inhibitory concentration (MIC) was determined using the Kirby-Bauer method, the minimum bactericidal concentration (MBC) was determined using the streaking method of the inhibition zone formed, and the mechanism of bacterial membrane leakage cell was measured using UV-VIS spectrophotometry at wavelengths of 260 and 280 nm. The MIC value was found to be 3.125 mg/mL in both bacteria, with an inhibition zone of 6.43 ± 0.06 mm (K. pneumoniae) and 6.73 ± 0.15 mm (P. mirabilis). The MBC value at 200 mg/mL with a percent reduction of 98.35 % (K. pneumoniae) and at 100 mg/mL with a percent reduction of 98.06 % (P. mirabilis). The supernatant of a membrane leakage cell (DNA and protein) was absorbed at wavelengths of 260 and 280 nm. It can be concluded that the ethanolic extract of avocado leaves has antibacterial potential against clinical isolates of K. pneumoniae and P. mirabilis. HIGHLIGHTS Avocado leaves, which are typically discarded, can be repurposed as a potent antibacterial agent in traditional medicine Demonstrates a potent minimum inhibitory concentration with a minimum bactericidal concentration value that can effectively suppress bacterial growth Point number 2 is substantiated by the utilization of DNA and protein cell leakage tests, as evidenced by absorbance measurements at wavelengths of 260 and 280 nm Flavonoid secondary metabolite have been successfully identified as one of the active components using the TLC analysis method GRAPHICAL ABSTRACT