Journal of Pathogens最新文献

Background: Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) is a common food-borne pathogen that causes gastroenteritis and can lead to life-threatening systemic disease when it spreads to vital organs, such as the liver. Stimulator of interferon genes (STING) is a crucial regulator of the host's innate immune response to viral infections, while its role in bacterial infections remains controversial. This study aims to establish a STING-deficient HepG2 cell line through the CRISPR/Cas9 system and evaluate its effects on Salmonella replication.

Methods: In this study, a STING knockout HepG2 cell line was constructed through the application of CRISPR/Cas9 technology. We assessed cell viability and proliferation using the CCK-8 assay. Subsequently, we investigated the effect of STING deletion on Salmonella replication and the expression of type I interferon-related genes.

Results: The STING knockout HepG2 cell line was successfully constructed using the CRISPR/Cas9 system. The proliferation capability was diminished in STING-deficient HepG2 cells, while Salmonella Typhimurium replication in these cells was augmented compared to the wild-type (WT) group. Following Salmonella infection, the transcriptional responses of type I interferon-related genes, such as IFNB1 and ISG15, were inhibited in STING-deficient HepG2 cells.

Conclusions: We successfully constructed a STING-deficient cell line. Our finding of increased Salmonella Typhimurium replication in STING-deficient HepG2 cells provides the basis for further studies on pathogen-host interactions.

Aim: The increasing antibiotic resistance and the ability to form biofilms in medical devices have become the leading cause of severe infections associated with Staphylococcus aureus (S. aureus). Since the bacteria living in biofilms can exhibit 10- to 1,000-fold increase in antibiotic resistance and implicate chronic infectious diseases, the detection of S. aureus ability to form biofilms is of great importance for managing, minimizing, and effectively treating infections caused by it. This study aimed to compare the tube and tissue culture methods to detect biofilm production and antibiotic susceptibility in MRSA and MSSA.

Materials and methods: The S. aureus isolates were identified by the examination of the colony morphology, Gram staining, and various biochemical tests. Antimicrobial susceptibility testing of all isolates was performed by the modified Kirby-Bauer disc diffusion method as recommended by CLSI guidelines. MRSA screening was performed phenotypically using a cefoxitin disc (30 µg). Isolates were tested for inducible resistance using the D-test, and two phenotypic methods detected biofilm formation.

Results: Among 982 nonrepeated clinical specimens, S. aureus was isolated from 103 (10.48%). Among 103 clinical isolates of S. aureus, 54 (52.42%) isolates were MRSA, and 49 (47.57%) were MSSA. Among 54 MRSA isolates, the inducible MLSB phenotype was observed in 23/54 (42.59%) with a positive D-test. By TCP method, 26 (48.1%) MRSA isolates were strong biofilm producers, whereas, among all MSSA isolates, only 6 (12.2%) were strong biofilm producers.

Conclusion: MRSA showed strong biofilm production in comparison with MSSA. The TCP method is a recommended reliable method to detect the biofilm among S. aureus isolates, and the TM method could be useful for the screening of biofilm production in S. aureus in the routine clinical laboratory.

Background: Enterococci are clinically significant because of their increasing antibiotic resistance and their ability to cause severe infections due to an arsenal of virulence genes. Few studies in the developing world have examined virulence factors that may significantly impact patient outcomes. This study describes the antimicrobial resistance profiles and prevalence of five key Enterococcal virulence genes gelE, asa, cylA, esp, and hyl in forty-four clinical Enterococcus faecalis and E. faecium isolates in Kenya and their association with patients' demographic and clinical characteristics.

Results: All E. faecium isolates were obtained from hospital-acquired skin and soft tissue infections. While E. faecalis was associated with community-acquired urinary tract infections. All isolates were resistant to erythromycin, whereas 11/44 (27.5%), 25/44 (56.8%), 28/44 (63.6%), 37/44 (84.1%), 40/44 (90.0%), and 43/44 (97.5%) were susceptible to tetracycline, levofloxacin, gentamicin, ampicillin, nitrofurantoin, and teicoplanin, respectively. All isolates were susceptible to tigecycline, vancomycin, and linezolid. There was little difference in the antibiotic resistance profiles between E. faecalis and E. faecium. The prevalence of the virulence genes among the 44 isolates were 27 (61.4%) for gelE, 26 (59.1%) for asa1, 16 (36.3%) for esp, 11 (25.0%) for cylA, and 1 (2.3%) for hyl. 72.9% of E. faecalis isolates had multiple virulence genes compared to 57% of E. faecium isolates with no virulence genes. The hyl gene was only detected in E. faecium, while cylA and asa1 were only detected in E. faecalis. A significant correlation was observed between the presence of asa1 and esp virulence genes and tetracycline resistance (P=0.0305 and 0.0363, respectively). A significant correlation was also observed between the presence of virulence genes gelE and asa1 and nitrofurantoin resistance (P=0.0175 and 0.0225, respectively) and ampicillin resistance (P=0.0005 and 0.0008, respectively).

Conclusion: The study highlights the high levels of erythromycin resistance in E. faecalis and E. faecium, the demographic factors influencing the species distribution among patients, and the accumulation of multiple virulence genes in E. faecalis. The significant association of gelE, asa1, and esp virulence genes with drug resistance could explain the pathogenic success of E. faecalis and provides a guide for future studies.

Objective: The study aimed to describe the pattern of causative microorganisms, drug susceptibility, risk factors of antibiotic-resistant bacterial infection, and clinical impact of these organisms on pediatric oncology patients with febrile neutropenia.

Methods: A retrospective descriptive study of oncologic patients aged less than 15 years who were diagnosed with febrile neutropenia in King Chulalongkorn Memorial Hospital was conducted between January 2013 to December 2017. Characteristics and clinical outcomes of febrile neutropenia episodes, causative pathogens, and their antibiotic susceptibilities were recorded.

Result: This study included 267 patients with 563 febrile neutropenia episodes. The median (range) age was 5.1 years (1 month-15 years). The most common underlying disease was acute lymphoblastic leukemia (42.7%). Of 563 febrile episodes, there were 192 (34.1%) with microbiologically documented infection. Among these 192 episodes of microbiologically documented infection, there were 214 causative pathogens: 154 bacteria (72%), 32 viruses (15%), 27 fungus (12.6%), and 1 Mycobacterium tuberculosis (0.4%). Gram-negative bacteria (48.6%) accounted for most of the causative pathogens. Twenty-three percent of them were multidrug resistant, and 18% were carbapenem resistant. Among Gram-positive bacterial infection which accounted for 23.4% of all specimens, the proportion of MRSA was 20%. The 2-week mortality rate was 3.7%. Drug-resistant Gram-negative bacterial infection caused significant adverse events and mortality compared to nonresistant bacterial infection (p < 0.05).

Conclusion: There is high rate of drug-resistant organism infection in pediatric oncology patients in a tertiary-care center in Thailand. Infection with drug-resistant Gram-negative bacterial infection was associated with significant morbidity and mortality. Continuous surveillance for the pattern of drug-resistant infections is crucial.

Background: Regardless of the global concerted effort to control the development and spread of antimicrobial resistance, increasing cases are continually documented at many medical centres. This situation is reinforced by inadequate information on the trend of resistance resulting from lack of regular antimicrobial resistance surveillance. The present study sought to detect the number of multidrug-resistant (MDR), extended drug-resistant (XDR), and pandrug-resistant (PDR) bacterial isolates at a health facility in Ghana from January 2018 to July 2020.

Method: A total of 800 data on antimicrobial testing results were extracted from the records of the health facility. The extracted data were explored for the detection of MDR, XDR, and PDR. The study further determined the use of antibiotics using the multiple-drug resistance index (MDRI).

Results: Except for Staphylococcus and Neisseria spp., all bacterial isolates showed extremely high (100%) proportion of MDR. Although only Staphylococcus spp. (38 (4.8%)) was observed to be XDR, the rest of the bacteria showed the potential to attain the status of XDR or PDR. MDRI indicated high use of antibiotics in the health facility.

Conclusion: The high antimicrobial resistance observed by the study underscores the need for prompt and effective antibiotic resistance control strategies.

Background: Bambusa vulgaris (Tabashir) has been shown to have antimicrobial, antioxidant, and anti-inflammatory effects due to the presence of ascorbic acid, vitamin B2, flavonoid, and phenolic compounds which can be beneficial in the process of wound healing. The current study aimed to evaluate the effects of topical Tabashir extract on cutaneous leishmaniasis (CL) caused by Leishmania major in BALB/c mice.

Methods: Twenty-eight female BALB/c mice (4 weeks old, 18 ± 4 grams) were injected subcutaneously in tail-base with L. major amastigotes. Treatment started when the CL lesions were appeared and continued for 21 days. Mice were then divided into four groups: E1, treated daily with 5% of Tabashir extract gel; E2, treated daily with 10% Tabashir gel; C1, irrigated daily only with normal saline; and C2, received vehicle gel daily. The wounds' sizes were measured every 3 days, using vernier caliper. The volume densities of vessels, collagens, and hair follicles, vessels' length density, and mean diameter were soteriologically determined.

Results: Tabashir enhanced wound closure rate through increasing the number of fibroblasts, collagen bundles, and vessels, according to histomorphometric evaluation while it did not affect the parasitic load. Findings of the in vitro study revealed that the extract has substantial mortality for the Leishmania promastigotes.

Conclusion: Topical Tabashir showed promising effects on the healing process of skin wounds caused by CL in this experimental study. Further studies are suggested to find out the molecules which are involved in the healing process.