Microbial drug resistance最新文献

Carbapenenemase producers, particularly the metallo-β-lactamase (MBL) types in Pseudomonas aeruginosa, have emerged as an urgent threat in health care settings. MBLs require zinc at their catalytic site and can be inhibited by dimercaptosuccinic acid (DMSA), a metal chelator known for the treatment of lead and mercury intoxication. Isogenic strains of wild-type and OprD-deleted P. aeruginosa PA14, were constructed, producing the MBLs VIM-2, NDM-1, SPM-1, IMP-1, and AIM-1, or the non-MBL carbapenemases, GES-5 and KPC-2. In addition, 59 previously characterized clinical isolates of P. aeruginosa producing different ß-lactamases (including carbapenemases), and with known outer-membrane porin OprD status, were utilized. Minimal inhibitory concentrations values of imipenem and meropenem, and DMSA combinations were determined, and time-kill assays were performed with PA14 expressing VIM-2. Results indicated a significant additive effect of DMSA (most effective at 3 mM) and carbapenems in recombinant and clinical strains of P. aeruginosa expressing MBLs, in particular against VIM producers, which are the most prevalent carbapenemases in P. aeruginosa. This effect was best evidenced with meropenem and in strains without OprD modification. DMSA shows promising efficacy, particularly in combination therapy with meropenem, for treating infections caused by MBL-producing P. aeruginosa.

Aztreonam/avibactam (ATM/AVI) has been recently approved drug for clinical use in the European Union. The aim of this study was to develop and evaluate a novel selective medium for the isolation of ATM/AVI-resistant strains (Super ATM/AVI selective medium) to help to control their spread. Minimum inhibitory concentrations of ATM/AVI were determined using the broth microdilution method for 77 Gram-negative isolates, including 62 Enterobacterales and 15 Pseudomonas aeruginosa. The Super ATM/AVI selective medium was elaborated using optimal final concentrations of ATM at 5 mg/L and AVI at 4 mg/L, being supplemented with amphotericin B and vancomycin to prevent growth of yeasts and Gram-positive bacteria and with ZnSO₄ to optimize the expression of metallo-β-lactamase producers. Super ATM/AVI showed high sensitivity (94.6%) and specificity (100%) at a detection limit of 10³ CFU/mL.

This study aimed to characterize the first vancomycin-resistant Enterococcus faecalis (VREfs) isolate from patient with neutropenic in Tunisia by whole-genome sequencing (WGS). This strain was detected from routine rectal swab from an 8-year-old child with bone marrow aplasia, residing in a rural area, on September 20, 2021. The strain was isolated after 12 days of hospitalization at the National Bone Marrow Transplant Center. Minimum Inhibitory Concentrations of vancomycin and teicoplanin were >256 and 16 mg/L, respectively. WGS revealed that the strain belonged to the ST249 clone, exclusively reported in avian (poultry and ducks) vancomycin-susceptible E. faecalis isolates in six studies from four countries, primarily Denmark. The vanA gene was carried by the Tn1546 transposon mobilized by a pTW9-like plasmid. The ardA gene, a CRISPR-Cas system neutralization factor, was detected in this strain. In summary, this is the first report of avian-associated E. faecalis ST249 in clinical samples. Initially vancomycin susceptible, the strain acquired a pTW9-like plasmid carrying the classical vanA-Tn1546 transposon. This acquisition was facilitated by the sex pheromone-response mechanisms and the ardA gene and CRISPR-Cas system neutralization.

Tigecycline is a last-resort antimicrobial in humans. Tetracyclines are the most widely used antimicrobials in livestock. Mobile tigecycline resistance genes [tet(X)] are disseminated worldwide, and tetracycline use may have promoted the selection of tet(X) genes. Thus, the selective pressure on tet(X) genes and their plasmids in livestock must be elucidated. We performed a retrospective study to clarify the prevalence of tigecycline-resistant Escherichia coli from pigs in Thailand. Screening for tigecycline resistance was performed on 107 E. coli strains from 25 samples, and tet(X)-carrying plasmids were characterized. tet(X) genes were cloned and expressed in E. coli. Bacterial growth rate in the presence of tetracycline as a result of the presence of tet(X) genes was also evaluated. Thirty-two tet(X4)-harboring tigecycline-resistant E. coli strains were detected in 10/25 samples (40%). The tet(X4) genes were carried on various Inc-type plasmids and flanked by ISCR2. The tet(X)-carrying plasmids were transferred to E. coli and Klebsiella pneumoniae. Acquisition of tet(X) genes and their plasmids improved bacterial growth in the presence of tetracycline. In summary, tetracycline use exerts selective pressure on tet(X) genes and their various backbone plasmids; therefore, a reduced amount of tetracycline use is important to limit the spreading of tet(X) genes.

Salmonella infections have become increasingly resistant to antibiotics, including fluoroquinolones, third-generation cephalosporins (C3G), and even carbapenems. This report describes the emergence of a strain of Salmonella enterica serovar Heidelberg that produces the carbapenemase OXA 48. The strain was isolated from a stool sample taken from a newborn. Antimicrobial susceptibility testing was carried out following the recommendations of the Clinical and Laboratory Standard Institute. Whole genome sequencing was performed on MiSeq Illumina™. The strain was resistant to ertapenem (minimal inhibitory concentration [MIC] = 12 µg/mL), intermediate to imipenem (MIC = 1.5 µg/mL), resistant to nalidixic acid, and intermediate to fluoroquinolones but was susceptible to C3G, cotrimoxazole, chloramphenicol, and colistin (MIC = 0.064 µg/mL). The strain was identified as ST-15. The strain of Salmonella Heidelberg ST-15 was found to have antimicrobial resistance genes, specifically blaOXA-48, aac(6')-Iaa and fosA7, which mediate resistance to carbapenems, aminoglycosides and fosfomycin, respectively. Additionally, mutations were detected in the gyrA, parC. Three plasmid replicon type IncL, IncX1, and Col156 have been identified. The strain has the potential to cause an epidemic. The genomic analysis of the strain allowed us to understand the mechanisms of resistance. Preventing the spread of Salmonella carbapenemase-producing strains is crucial, particularly in hospital settings. Epidemiological measures are necessary to achieve this goal.

The global increase in carbapenem resistance poses a significant public health threat due to the potential emergence of multidrug-resistant pathogens and limited treatment options. To learn more about this issue and offer potential solutions, we conducted a study of carbapenem-resistant Pseudomonas aeruginosa (CRPA) infections in a secondary care hospital setting. The study utilized the carbapenem inactivation method (CIM), a leading phenotypic analysis, to determine carbapenemase activity in 63 CRPA isolates. Additionally, polymerase chain reaction (PCR) analysis was conducted to test for the presence of carbapenemase genes associated with the production or expression of various carbapenemase enzymes, including bla_KPC, bla_NDM, bla_VIM, bla_OXA-48, bla_IMP, and bla_GES. Arbitrary primed PCR (AP-PCR) was performed to assess the clonal relationship between different isolates. The isolates were also classified as either health care-associated infections or community-acquired infections, and their clonal relationship and gene positivity were evaluated. A total of 63 CRPA samples underwent evaluation, with 14 isolates determined to be carbapenemase producers via CIM tests. PCR assays revealed that 14 isolates carried carbapenemase genes, with 9 carrying bla_NDM, 2 carrying bla_GES, 2 carrying bla_VIM, and 1 carrying bla_IMP. CRPA exhibited a 22% prevalence of carbapenemase genes, of which 64% were attributed to the NDM gene responsible for multidrug resistance. AP-PCR revealed high clonal diversity among the isolates. Molecular epidemiological evaluation also showed no dominant outbreak strain among PA isolates. This study presents significant data on the prevalence and distribution of carbapenemase-producing CRPA strains isolated from secondary health care facilities. Typically, the literature focuses on resistance rates in tertiary care public hospitals. These findings may aid in understanding resistance and its mechanisms, as well as in developing effective treatment strategies and infection control measures.

This study aimed to evaluate the contamination levels of fresh products by ESBLs-producing Enterobacterales (ESBLs-E) or AmpC-producing Enterobacterales and characterize ESBLs genes. A total of 132 samples (67 vegetables and 65 fruits) were collected from markets in Tebessa, eastern Algeria. Among the samples, 16 third-generation cephalosporin-resistant Enterobacterales isolates were identified with a prevalence of 19.40% in vegetable samples, while there was no positive finding in fruit samples. Isolates showed resistance to most β-lactams, and all of them displayed multidrug resistance. Phenotypic tests for ESBLs detection, using double-disk synergy test and double-disk test were positive for 14 strains, including Klebsiella pneumoniae (n = 5), Klebsiella oxytoca (n = 4), Klebsiella terrigena (n = 2), Kluyvera spp. (n = 2), and Enterobacter cloacae (n = 1). Two AmpC-producing strains (Citrobacter freundii and E. cloacae) were identified through the AmpC disk test. Contamination rates of vegetables by ESBLs-E and AmpC-producing Enterobacterales were 19.40% and 2.98%, respectively. PCR results showed the presence of at least one ESBL gene in seven selected strains, with the dominance of bla_CTX-M gene. Notably, K. pneumoniae strains showed the co-occurrence of two or three genes. Sequencing identified uncommon variants of ESBLs genes for the first time in Algeria, including bla_CTX-M-79 (2/7), bla_CTX-M-107 (2/7), bla_CTX-M-117 (2/7), bla_TEM-112 (1/7), bla_TEM-125 (2/7), bla_TEM-194 (1/7), and bla_SHV-176 (3/7).

Colibacillosis caused by avian pathogenic Escherichia coli (APEC) is causing economic losses to the global poultry industry. Increased prevalence of antibiotic resistance in APEC is the leading cause for increased indiscriminate use of various antimicrobial compounds in farms. The study aimed to investigate the presence of phenotypic and genotypic markers for antibiotic resistance, metals, and biocides in APEC from Bangladeshi poultry and details about the antimicrobials used in poultry farms. In total, 55 APEC were isolated from hearts or liver samples of 86 sick or dead chickens using culture on agar plate and biochemical testing. APEC isolates were tested for antibiotic susceptibility to 14 antimicrobial agents according to the European Committee on Antimicrobial Susceptibility Testing. A series of PCRs was performed to screen the presence of genes for quinolones, colistin, aminoglycosides, ESBL, metals, and biocides. Detailed information regarding antibiotic use was collected from farmers during clinical investigations. Resistance was found to 10 antibiotics and prevalence was as follows: ampicillin (86%), ciprofloxacin (86%), trimethoprim-sulphamethoxazole (73%), chloramphenicol (33%), mecillinam (13%), gentamicin (11%), cefoxitin (11%), cefotaxime (9%), tigecycline (2%), and nitrofurantoin (2%). The most common multiresistance phenotype was CIP-AMP-SXT, and 35% of isolates were multidrug resistant. Genotypic analysis confirmed the presence of quinolone resistance genes [qnrS1 and aac-(6')-lb-cr], silver-resistant genes (silE), and mercury-resistant genes (merA) but not others. In total, 88% farmers were using different antimicrobial compounds, and, of them, 56% were using antimicrobials without prescriptions from veterinarians. Ciprofloxacin was most extensively used followed by oxytetracycline. Critically important antibiotics like ciprofloxacin, colistin, and gentamicin are extensively used in the farms. This study confirmed the presence of antibiotics, metals, and biocide-resistant APEC in poultry farms in Bangladesh. Increased resistance to quinolones is a serious ongoing problem. The indiscriminate use of antibiotics in poultry farms is alarming and should be stopped.

Objectives: Levonadifloxacin (IV) and alalevonadifloxacin (oral) are novel broad-spectrum anti-methicillin-resistant Staphylococcus aureus (S. aureus) agents based on novel benzoquinolizine core. Both are recently approved in India for the treatment of acute bacterial skin and skin structure infections, including diabetic foot infections and concurrent bacteremia. The present investigation reports the findings from preclinical pharmacokinetic (PK) studies that support the development of levonadifloxacin as a treatment option for bone and joint infections (BJIs). Methods: PK profiles of levonadifloxacin were obtained in serum, and/or various anatomical segments of femoral bone such as whole bone (WB), hard bone (HB), and bone marrow (BM) following subcutaneous administration of levonadifloxacin single doses at 50, 100, 200, and 400 mg/kg, as well as multiple doses at 200 mg/kg (BID (two times a day), 6 hours apart) for 5 days in Wistar rats. Results: The distribution of levonadifloxacin in bone was rapid, and the extent of distribution (B/S ratio; bone-to-serum area under the concentration-time curve ratio) was nearly comparable across bone segments. In single-dosage PK studies, the mean B/S ratio in WB, HB, and BM was 0.40, 0.33, and 0.34, respectively; however, in 5 days' repeated dose studies, it increased to 1.01, 1.14, and 0.61, respectively. Conclusions: On the basis of bone PK data in Wistar rat and ever-growing clinical experience in terms of safety and efficacy, levonadifloxacin has the potential to offer a well-differentiated therapy for the treatment of BJIs.

Colistin HiMIC Plate Kit (HiMedia Laboratories), a new commercial broth microdilution (BMD) test for colistin susceptibility testing was evaluated. BMD according to ISO standard 20776-1 (2019) with two-fold dilutions from 128 to 0.125 mg/L was used as a reference method. The colistin reference MICs (minimal inhibitory concentration) ranged from 0,25 to 128 mg/L with 15 (20.5%; 15/73) isolates having colistin reference MICs close to the current EUCAST breakpoint (MICs of 2, 4, and 8 mg/L). The study assessed the compliance of a commercial kit with the CLSI criteria, including categorical agreement (CA) and essential agreement (EA ≥90%), very major error (VME rate) <3%, and major error (ME) rate <3%. On 73 carbapenemase-producing Klebsiella pneumoniae isolates Colistin HiMIC^TM Plate Kit showed CA and EA of 100% (73/73; 95% CI: 0.97-1.00) and 82.2% (60/73; 95% CI: 0.72-0.90), respectively. No ME (false-resistant results) and VME (false-susceptible results) were detected. Kit showed acceptable CA, ME, and VME error parameters, whereas the EA did not meet the ≥90% threshold. Laboratories must check for possible limitations of commercial kits before they can be used for colistin susceptibility testing.