OBJECTIVE

To determine the prevalence of rectal colonization with carbapenem-resistant organisms (CRO) among PGH neonatal intensive care unit (NICU) patients.

A prospective single-center observational study conducted over a 1-month period included all NICU 3 and cohort area patients admitted on April 24, 2024. Rectal swabs were collected for multidrug-resistant organism (MDRO) screening and repeated weekly for 1 month while admitted. Swabs were inoculated on chromogenic media, and isolates were identified and tested for antimicrobial sensitivity by disk diffusion. Clinical characteristics and outcomes were collected for 30 days from initial MDRO screening. Descriptive statistics were used to summarize the data.

The point prevalence of CRO colonization was 37% (14 of 38) at initial screening. There were 14 incident colonizations, hence the 4-week period prevalence of CRO colonization was 72.5% (29 of 40). The patients were mostly very preterm, very low birth weight neonates, majority were tested within the first 2 weeks of life, and half were exposed to meropenem at initial screening. Nosocomial infection developed in 29% and 64%, and 30-day mortality rate was 8% and 21% among initially non-CRO-colonized and CRO-colonized patients respectively. Despite high CRO colonization, no culture-proven CRO infection was observed. Surveillance screening documented persistent CRO colonization in 37%, but no decolonization. Escherichia coli, Klebsiella spp. and Serratia spp. were the most common colonizers.

The high prevalence of rectal CRO colonization in the NICU emphasizes the burden of antimicrobial resistance, but despite the high CRO colonization, no CRO infection was documented from the limited sample and study period.

Iron is an essential element for living organisms that plays critical roles in the process of bacterial growth and metabolism. However, it remains to be elucidated whether piuB encoding iron-uptake factor is involved in iron uptake and pathogenicity of Xanthomonas axonopodis pv. glycines (Xag). To investigate the function of piuB, we firstly generated a piuB deletion mutant (ΔpiuB) by homologous recombination. Compared with the wild-type, the piuB mutant exhibited significantly reduced growth and virulence in host soybean. The mutant displayed markedly increased siderophore secretory volume, and its sensitivity to Fe³⁺, Cu²⁺, Zn²⁺ and Mn²⁺ was significantly enhanced. Additionally, the H₂O₂ resistance, exopolysaccharide yield, biofilm formation, and cell mobility of ΔpiuB were significantly diminished compared to that of the wild-type. The addition of exogenous Fe³⁺ cannot effectively restore the above characteristics of ΔpiuB. However, expressing piuB in trans rescued the properties lost by ΔpiuB to the levels in the wild-type. Taken together, our results demonstrated that PiuB is a potential factor for Xag to assimilate Fe³⁺, and is necessary for Xag to be pathogenic in host soybean.
Iron ; Glycine max ; Virulence ; Xanthomonas axonopodis/genetics* ; Hydrogen Peroxide

Objective: To report a case of acute postoperative endophthalmitis following cataract surgery due to Pseudomonas stutzeri in a healthy elderly male. Methods: This is a case report. Results: A non-hypertensive, non-diabetic male in his late 60s consulted due to eye pain and blurred vision 5 days after an uncomplicated extracapsular cataract extraction with posterior chamber intraocular lens implantation (PCIOL) on his left eye. On examination, the visual acuity was light perception. Slit-lamp examination showed ciliary injection, conjunctival congestion, mild corneal edema with Descemet membrane folds, hazy anterior chamber with fibrin and a 2-millimeter hypopyon, and a visible PCIOL. IOP was 10 mmHg with no leak on Seidel’s test, and there was poor view of the fundus. B-scan ultrasonography showed findings consistent with endophthalmitis. He was given topical, intravitreal, and systemic antibiotics, and emergency vitrectomy was done. The vitreous sample culture revealed Pseudomonas stutzeri. Despite aggressive medical and surgical management, vision loss was not prevented. Conclusion Acute postoperative endophthalmitis from Pseudomonas stutzeri is rare; if not recognized and treated promptly, this complication has devastating outcomes. It may present with a fulminant course regardless of the associated risks for infection. Prevention, early recognition, and timely management can prevent unfavorable visual outcomes.
Endophthalmitis ; Pseudomonas stutzeri

Introduction: Intensive care unit (ICU) patients are at the greatest risk of acquiring nosocomial infections, partly because of their serious underlying disease, but also by exposure to life-saving invasive procedures. Hospital-acquired infections increase patient morbidity, increase the length of hospital stay and hospital costs, and also increases mortality rate. The basic knowledge of organisms infecting ICU patients is very important to empirically select appropriate antibiotics, so that the most likely infecting organisms are addressed. Objective: The aim of the study was to find out the etiologic agents causing infection in medical intensive care unit patients. Results In our study of 289 patients, 180 (62.3%) showed a growth of organism during the stay in ICU. The most common site of infection was the respiratory tract in 138 patients (47.8%) with 60 patients (20.8%) showing Acinetobacter baumannii.
Cross Infection ; Intensive Care Units ; Acinetobacter baumannii ; Respiration, Artificial

Pyocin S2 and S4 in Pseudomonas aeruginosa use the same uptake channels as the pyoverdine does in bacteria, indicating a possible connection between them. In this study, we characterized the single bacterial gene expression distribution of three S-type pyocins (Pys2, PA3866, and PyoS5) and examined the impact of pyocin S2 on bacterial uptake of pyoverdine. The findings demonstrated that the expression of the S-type pyocin genes was highly differentiated in bacterial population under DNAdamage stress. Moreover, exogenous addition of pyocin S2 reduces the bacterial uptake of pyoverdine so that the presence of pyocin S2 prevents the uptake of environmental pyoverdine by non-pyoverdine synthesizing 'cheaters', thereby reducing their resistance to oxidative stress. Furthermore, we discovered that overexpression of the SOS response regulator PrtN in bacteria significantly decreased the expression of genes involved in the synthesis of pyoverdine, significantly decreasing the overall synthesis and exocytosis of pyoverdine. These findings imply a connection between the function of the iron absorption system and the SOS stress response mechanism in bacteria.
Pyocins/metabolism* ; Pseudomonas aeruginosa/metabolism*

Manipulation of genes, including knock-out or knock-in, replacement of gene elements (such as promoters), fusion with a fluorescent protein gene, and construction of in situ gene reporter, is required in most of the biotechnological laboratories. The widely used gene manipulating methods based on two-step allelic exchange are cumbersome in terms of constructing plasmids, transforming and screening. In addition, the efficiency of using this method for long fragment knockout is low. To simplify the process of gene manipulation, we constructed a minimized integrative vector pln2. When a gene needs to be inactivated, an internal fragment of the target gene (non-frameshift) is cloned into the pln2 plasmid. Once the single-crossover recombination between genome and the constructed plasmid occurs, the endogenous gene is segmented by the plasmid backbone and thus inactivated. We developed a toolbox based on pln2 that can be used for different genomic operation mentioned above. With the help of this toolbox, we successfully knocked out large fragments of 20-270 kb.
Genetic Vectors/genetics* ; Pseudomonas aeruginosa/genetics* ; Plasmids/genetics* ; Promoter Regions, Genetic ; Genome

OBJECTIVE: To investigate the distribution and drug sensitivity of pathogenic bacteria isolated from patients in hematology department, in order to provide evidence for rational use of antibiotics in clinic. METHODS: The distribution of pathogenic bacteria and drug sensitivity data of patients in the hematology department of The First Affiliated Hospital of Nanjing Medical University from 2015 to 2020 were retrospectively analyzed, and the pathogens isolated from different specimen types were compared. RESULTS: A total of 2 029 strains of pathogenic bacteria were isolated from 1 501 patients in the hematology department from 2015 to 2020, and 62.2% of which were Gram-negative bacilli, mainly Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Stenotrophomonas maltophilia and Acinetobacter baumannii. Gram-positive coccus accounted for 18.8%, mainly Coagulase-negative staphylococcus (CoNS) and Staphylococcus aureus. Fungi (17.4%) were mainly candida. The 2 029 strains were mainly isolated from respiratory tract (35.1%), blood (31.8%) and urine (19.2%) specimens. Gram-negative bacilli were the main pathogenic bacteria in different specimen types (>60%). K. pneumoniae, S. maltophilia and A. baumannii were the most common pathogens in respiratory specimens, E. coli, CoNS, K. pneumoniae and P. aeruginosa were common in blood samples, and E. coli and Enterococcus were most common in urine samples. Enterobacteriaceae had the highest susceptibility to amikacin and carbapenems (>90.0%), followed by piperacillin/tazobactam. P. aeruginosa strains had high sensitivity to antibiotics except aztreonam (<50.0%). The susceptibility of A. baumannii to multiple antibiotics was less than 70.0%. The antimicrobial resistance rates of E. coli and K. pneumoniae in respiratory tract specimens were higher than those in blood specimens and urine specimens. CONCLUSION Gram-negative bacilli are the main pathogenic bacteria isolated from patients in hematology department. The distribution of pathogens is different in different types of specimens, and the sensitivity of each strain to antibiotics is different. The rational use of antibiotics should be based on different parts of infection to prevent the occurrence of drug resistance.
Humans ; Escherichia coli ; Retrospective Studies ; Bacteria ; Anti-Bacterial Agents/therapeutic use* ; Gram-Negative Bacteria ; Drug Resistance ; Pseudomonas aeruginosa ; Hematology

BACKGROUND AND OBJECTIVE: Many opportunistic and nosocomial pathogens like Pseudomonas aeruginosa are very reliant on a bacterium-to-bacterium communication system called quorum sensing (QS). Without the aforementioned process, gene expressions associated with virulence factors will not be produced. In this study, the sub-inhibitory concentrations (sub-MICs) of methanolic leaf extract and obtained fractions from Averrhoa bilimbi (kamias) were screened for ability to inhibit quorum sensing-controlled phenotypes of P. aeruginosa ATCC 27853. METHODOLOGY: A. bilimbi crude extract was fractionated through liquid-liquid extraction, producing four (4) fractions: hexane fraction, dichloromethane (DCM) fraction, ethyl acetate (EtOAc) fraction, and water (H2O) fraction. Among the sub-MICs obtained from resazurin-based fluorimetric microtiter assay, only 50 μg/mL was utilized in evaluating the anti-QS properties of crude extract and fr RESULTS: In the swarming motility assay, hexane fraction (9.39 mm ± 0.67) and DCM fraction (10.82 mm ± 0.95) displayed restriction in the treated P. aeruginosa ATCC 27853 swarms against the control (16.20 mm ± 2.55). In the anti-pyocyanin production assay, hexane fraction exhibited an inhibition of 42.66 % ± 12.94. TLC analysis and phytochemical screening revealed that hexane fraction contains steroids, terpenes, triterpenes, and glycolipids; and DCM fraction contains cardiac glycosides, triterpenoids, terpenes, triterpenes, steroids, alkaloids, and glycolipids. CONCLUSION Hexane and DCM fractions obtained from A. bilimbi significantly inhibited swarming of P. aeruginosa ATCC 27853 while none of the extracts were able to significantly inhibit pyocyanin formation of P. aeruginosa ATCC 27853.
Pseudomonas aeruginosa ; Averrhoa bilimbi ; quorum sensing ; pyocyanin

Introduction: Pseudomonas aeruginosa is an opportunistic, gram-negative bacillus that can contaminate skin or open wounds to cause skin infections that are historically difficult to manage. The pathogenesis of green nail syndrome (GNS) begins with hyperhydration (occlusion, sweating, maceration) or destruction (microtrauma, dermatitis) of the epidermis thus disrupting the physical barrier, leading to the colonization and proliferation of P. aeruginosa. This case explores the off-label use of nadifloxacin, a fluoroquinolone approved for acne and bacterial skin infections in some countries, to treat a case of GNS. Case Report: This is a case of a 31-year-old Filipino female who presented with a four-month history of green discoloration of the lateral portion of the right thumbnail with a medical history of antiphospholipid antibody syndrome and rheumatoid arthritis. Clinical examination showed a dystrophic thumbnail with greenish discoloration, erythema and swelling around the base of the cuticle, and distal onycholysis. Laboratory findings revealed co-infection of P. aeruginosa and Candida parapsilosis. The patient was effectively treated with topical nadifloxacin and oral fluconazole. Conclusion This case highlights the possibility of fungal and polymicrobial infections in GNS and suggests a novel, easy-to-use, and cost-effective alternative treatment to GNS secondary to P. aeruginosa in the form of topical nadifloxacin.
Candida parapsilosis ; Pseudomonas aeruginosa ; Onychomycosis

Objective:b> To analyze the drug resistance and genomic characteristics of Salmonella enterica serovar London isolated from clinical and food sources in Hangzhou City from 2017 to 2021. Methods:b> A total of 91 Salmonella enterica serovar London strains isolated from Hangzhou City from 2017 to 2021 were analyzed for drug susceptibility, pulsed field gel electrophoresis (PFGE) typing and whole genome sequencing. Multilocus sequence typing (MLST), core genome multilocus sequence typing (cgMLST) and detection of drug resistance genes were performed by using the sequencing data. Phylogenetic analysis was conducted to compare the 91 genomes from Hangzhou City with 347 genomes from public databases. Results:b> No significant difference in the drug resistance rate was observed between clinical strains and food strains to 18 drugs in Hangzhou City(all P>0.05), and the multidrug resistance (MDR) rate was 75.8% (69/91). Most strains were resistant to 7 drug classes simultaneously. One strain was resistant to Polymyxin E as well as positive for mcr-1.1, and 50.5% (46/91) of the strains were resistant to Azithromycin and were positive for mph(A). All 91 Salmonella enterica serovar London strains were ST155, which were subdivided into 44 molecular types by PFGE and 82 types by cgMLST. Phylogenetic analysis showed that most strains from Hangzhou City (83/91) were clustered together, and a small number of human isolates from Europe, North America and pork isolates from Hubei and Shenzhen were mixed in the cluster. Other strains from Hangzhou City (8/91) were closely related to strains from Europe, America and Southeast Asia. Strains isolated from pork were the most closely related to clinical strains. Conclusion:b> The epidemic of Salmonella enterica serovar London in Hangzhou City is mainly caused by the spread of ST155 strains, which is mainly transmitted locally. At the same time, cross-region transmission to Europe, North America, Southeast Asia, and other provinces and cities in China may also occur. There is no significant difference in the drug resistance rate between clinical strains and food strains, and a high level of MDR is found in the strains. Clinical infection of Salmonella enterica serovar London may be closely related to pork consumption in Hangzhou City.
Humans ; Salmonella enterica/genetics* ; Serogroup ; Anti-Bacterial Agents/pharmacology* ; Multilocus Sequence Typing ; Cities ; London ; Clonidine ; Phylogeny ; Genomics ; Drug Resistance ; Electrophoresis, Gel, Pulsed-Field ; Microbial Sensitivity Tests