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247800.9920Study on the resistance mechanism via outer membrane protein OprD2 and metal β-lactamase expression in the cell wall of Pseudomonas aeruginosa. The aim of the present study was to evaluate the imipenem-resistant mechanism via the outer membrane protein (OMP) OprD2 and metal β-lactamase expression in the cell wall of Pseudomonas aeruginosa. The Pseudomonas aeruginosa was clinically separated and validated by VITEK-2 full-automatic bacteria analyzer. Drug resistance, sensitive antibiotics and minimum inhibitory concentration (MIC) were tested using the drug sensitivity analysis system. The phenotype positive strains of MBL genes were screened using the Kirby-Bauer diffusion method by adding metal ion-chelating agent EDTA on the imipenem susceptibility paper. IMP-1, VIM-1 and SPM metaloenzyme genes were tested by polymerase chain reaction (PCR)-telomeric repeat amplification protocol (TRAP). The OMP OprD2 genes were tested by PCR-TRAP, and the protein expression was tested using western blot analysis. The location of OMP OprD2 was confirmed using the sodium salicylate inhibition test. The results showed that 80 portions (40%) of MBL-positive strains were screened out of 200 specimens. Imipenem-resistant Pseudomonas aeruginosa (IRPA) and MIC values were significantly higher than quality control bacteria and control bacteria (P<0.05). A total of 35 cases with IMP-1 positive, 20 with VIM-1 positive, 16 with SPM positive, 5 with 2 positive genes and 4 with 3 positive genes were screened among MBL positive strains. A total of 150 portions (75%) of OprD2 deficiencies were screened from 200 specimens. The standard strains and sensitive strains showed OprD2 protein bands at 45 kDa while no OprD2 protein bands appeared in OprD2 deficiency strains. It was in accordance with gene detection. In conclusion, OMP OprD2 deficiency and MBL phenotype positivity may be important mechanisms of IRPA.201627882088
247910.9918Down-regulatory effects of green coffee extract on las I and las R virulence-associated genes in Pseudomonas aeruginosa. BACKGROUND: Antibiotic resistant strains of Pseudomonas aeruginosa are the cause of Gram negative nosocomial infections especially among the immunosuppressed patients. The bacteria contains las I and las R genes that play very important roles in the pathogenesis and mechanisms of aggression. These genes can be influenced by the quorum sensing (QS) system and such mechanism is becoming clinically important worldwide. This study aimed to investigate the preventive effects of green coffee extract (GCE) on the expression of pathogenesis-related genes, las I and las R in P. aeruginosa. METHODS: A total of fifty four P. aeruginosa strains were isolated out of 100 clinical samples collected from the infectious wards in different hospitals (Tehran province) using conventional microscopic and biochemical methods. Susceptibility of the isolates to different antibiotics, GCE and chlorogenic acid were elucidated. Multiplex polymerase chain reaction (PCR) and real-time PCR were performed to detect and quantify the expression levels of las I and las R genes. The presence of chlorogenic acid in GCE was confirmed by HPLC. RESULTS: Antibiotic susceptibility tests revealed multidrug resistance among the clinical isolates of those 40 strains were resistant to ciprofloxacin (74.07%), 43 to ceftazidime (79.26%), 29 to amikacin (53.7%), 42 to ampicillin (77.77%), 17 to colistin (31.48%), 40 to gentamicin (74.77%), and 50 to piperacillin (92.59%). PCR outcomes exhibited that the frequency of las I and las R genes were 100% in resistant and sensitive strains isolated from clinical and standard strains of P. aeruginosa (ATCC 15449). Real-time PCR analyses revealed that GCE significantly prevented the expression of las I and las R genes in P. aeruginosa. GCE at concentration level as low as 2.5 mg/mL could prevent the expression of lasI and lasR genes in P. aeruginosa clinical isolates. CONCLUSION: The presence and expression levels of las I and las R genes in P. aeruginosa isolates were investigated when the bacteria was exposed to GCE. Our results tend to suggest that genes involved in pathogenesis of:Pseudomonas aeruginosa are down regulated by quorum sensing effect of chlorogenic acid and therefore GCE could be useful as an adjuvant in combating multidrug resistance strains of Pseudomonas aeruginosa.201931187452
537520.9911Mechanism of Eravacycline Resistance in Clinical Enterococcus faecalis Isolates From China. Opportunistic infections caused by multidrug-resistant Enterococcus faecalis strains are a significant clinical challenge. Eravacycline (Erava) is a synthetic fluorocycline structurally similar to tigecycline (Tige) that exhibits robust antimicrobial activity against Gram-positive bacteria. This study investigated the in vitro antimicrobial activity and heteroresistance risk of Eravacycline (Erava) in clinical E. faecalis isolates from China along with the mechanism of Erava resistance. A total of 276 non-duplicate E. faecalis isolates were retrospectively collected from a tertiary care hospital in China. Heteroresistance to Erava and the influence of tetracycline (Tet) resistance genes on Erava susceptibility were examined. To clarify the molecular basis for Erava resistance, E. faecalis variants exhibiting Erava-induced resistance were selected under Erava pressure. The relative transcript levels of six candidate genes linked to Erava susceptibility were determined by quantitative reverse-transcription PCR, and their role in Erava resistance and heteroresistance was evaluated by in vitro overexpression experiments. We found that Erava minimum inhibitory concentrations (MICs) against clinical E. faecalis isolates ranged from ≤0.015 to 0.25 mg/l even in strains harboring Tet resistance genes. The detection frequency of Erava heteroresistance in isolates with MICs ≤ 0.06, 0.125, and 0.25 mg/l were 0.43% (1/231), 7.5% (3/40), and 0 (0/5), respectively. No mutations were detected in the 30S ribosomal subunit gene in Erava heteroresistance-derived clones, although mutations in this subunit conferred cross resistance to Tige in Erava-induced resistant E. faecalis. Overexpressing RS00630 (encoding a bone morphogenetic protein family ATP-binding cassette transporter substrate-binding protein) in E. faecalis increased the frequency of Erava and Tige heteroresistance, whereas RS12140, RS06145, and RS06880 overexpression conferred heteroresistance to Tige only. These results indicate that Erava has potent in vitro antimicrobial activity against clinical E. faecalis isolates from China and that Erava heteroresistance can be induced by RS00630 overexpression.202032523563
228730.9910Expression of norA, norB and norC efflux pump genes mediating fluoroquinolones resistance in MRSA isolates. INTRODUCTION: Although fluoroquinolones are used to treat methicillin-resistant Staphylococcus aureus (MRSA)-induced infections, acquisition of antibiotic resistance by bacteria has impaired their clinical relevance. We aimed to evaluate the frequency of norA, norB, and norC efflux pump genes-mediating fluoroquinolones resistance and measure their expression levels in MRSA isolates. METHODOLOGY: 126 S. aureus isolates were collected from different clinical samples of adult hospitalized patients and identified by conventional microbiological methods. MRSA was diagnosed by cefoxitin disc diffusion method and minimum inhibitory concentration (MIC) of ciprofloxacin by broth microdilution method. The expression levels of efflux pump genes were measured by quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: 80 (63.5%) MRSA isolates were identified and showed high level of resistance to erythromycin (80%), gentamicin (75%), clindamycin (65%) and ciprofloxacin (60 %). norA, norB and norC were detected in 75%, 35% and 55% of the MRSA isolates respectively. norC was the most commonly overexpressed gene measured by qRT-PCR, occurring in 40% of MRSA isolates, followed by norA (35%) and norB (30%). The expression of these genes was significantly higher in ciprofloxacin-resistant than quantitative real-time PCR ciprofloxacin-sensitive MRSA isolates. CONCLUSIONS: This study showed high prevalence and overexpression of efflux pump genes among MRSA isolates which indicates the significant role of these genes in the development of multidrug resistance against antibiotics including fluoroquinolones.202438635612
228840.9910Resistance of Stenotrophomonas maltophilia to Fluoroquinolones: Prevalence in a University Hospital and Possible Mechanisms. OBJECTIVE: The purpose of this study was to investigate the clinical distribution and genotyping of Stenotrophomonas maltophilia, its resistance to antimicrobial agents, and the possible mechanisms of this drug resistance. METHODS: S. maltophilia isolates were collected from clinical specimens in a university hospital in Northwestern China during the period between 2010 and 2012, and were identified to the species level with a fully automated microbiological system. Antimicrobial susceptibility testing was performed for S. maltophilia with the Kirby-Bauer disc diffusion method. The minimal inhibitory concentrations (MICs) of norfloxacin, ofloxacin, chloramphenicol, minocycline, ceftazidime, levofloxacin and ciprofloxacin against S. maltophilia were assessed using the agar dilution method, and changes in the MIC of norfloxacin, ciprofloxacin and ofloxacin were observed after the addition of reserpine, an efflux pump inhibitor. Fluoroquinolone resistance genes were detected in S. maltophilia using a polymerase chain reaction (PCR) assay, and the expression of efflux pump smeD and smeF genes was determined using a quantitative fluorescent (QF)-PCR assay. Pulsed-field gel electrophoresis (PFGE) was employed to genotype identified S. maltophilia isolates. RESULTS: A total of 426 S. maltophilia strains were isolated from the university hospital from 2010 to 2012, consisting of 10.1% of total non-fermentative bacteria. The prevalence of norfloxacin, ciprofloxacin and ofloxacin resistance was 32.4%, 21.9% and 13.2% in the 114 S. maltophilia isolates collected from 2012, respectively. Following reserpine treatment, 19 S. maltophilia isolates positive for efflux pump were identified, and high expression of smeD and smeF genes was detected in two resistant isolates. gyrA, parC, smeD, smeE and smeF genes were detected in all 114 S. maltophilia isolates, while smqnr gene was found in 25.4% of total isolates. Glu-Lys mutation (GAA-AAA) was detected at the 151th amino acid of the gyrA gene, while Gly-Arg mutation (GGC-CGC) was found at the 37th amino acid of the parC gene. However, no significant difference was observed in the prevalence of gyrA or parC mutation between fluoroquinolone-resistant and -susceptible isolates (p> 0.05). The smqnr gene showed 92% to 99% heterogenicity among the 14 S. maltophilia clinical isolates. PFGE of 29 smqnr gene-positive S. maltophilia clinical isolates revealed 25 PFGE genotypes and 28 subgenotypes. CONCLUSIONS: Monitoring the clinical distribution and antimicrobial resistance of S. maltophilia is of great significance for the clinical therapy of bacterial infections. Reserpine is effective to inhibit the active efflux of norfloxacin, ciprofloxacin and ofloxacin on S. maltophilia and reduce MIC of fluoroquinolones against the bacteria. The expression of efflux pump smeD and smeF genes correlates with the resistance of S. maltophilia to fluoroquinolones.201525985315
522850.9909Mycobacterium bolletii respiratory infections. Contrary to other species in the Mycobacterium chelonae-abscessus complex, we reidentified M. bolletii strains isolated from 4 respiratory patients and found these strains to be uniformly resistant to clarithromycin. No mutations previously associated with macrolide resistance in bacteria were detected in either the 23S rDNA or the genes encoding riboproteins L4 and L22.200919193279
233760.9909Klebsiella pneumoniae susceptibility to biocides and its association with cepA, qacΔE and qacE efflux pump genes and antibiotic resistance. BACKGROUND: Although antiseptics are some of the most widely used antibacterials in hospitals, there is very little information on reduced susceptibility to these biocides and its relationship with resistance to antibiotics. AIM: To determine the relationship between reduced susceptibility to biocides and the carriage of antiseptic resistance genes, cepA, qacΔE and qacE, as well as identifying the role of efflux pumps in conferring reduced susceptibility. METHODS: Susceptibility was assessed for five biocides: chlorhexidine, benzalkonium chloride, Trigene, MediHex-4, Mediscrub; and for 11 antibiotics against 64 isolates of Klebsiella pneumoniae. Susceptibility to all compounds was tested by the agar double dilution method (DDM) and the effect of efflux pumps on biocides determined by repeating the susceptibility studies in the presence of the efflux pump inhibitor carbonyl cyanide m-chlorophenyl hydrazone (CCCP). The presence of the cepA, qacΔE and qacE genes was identified by polymerase chain reaction. FINDINGS: The bacteria were not widely antibiotic resistant though a few showed reduced susceptibility to cefoxitin, chloramphenicol and rifampicin and later-generation cephalosporins but not to carbapenems. Biocide susceptibility, tested by DDM, showed that 50, 49 and 53 strains had reduced susceptibility to chlorhexidine, Trigene and benzalkonium chloride, respectively. The antiseptic resistance genes cepA, qacΔE and qacE were found in 56, 34 and one isolates respectively and their effects as efflux pumps were determined by CCCP (10 mg/L), which decreased the minimum inhibitory concentrations (MICs) of chlorhexidine and Medihex-4 by 2-128-fold but had no impact on the MICs of benzalkonium chloride, Trigene and Mediscrub. CONCLUSION: There was a close link between carriage of efflux pump genes, cepA, qacΔE and qacE genes and reduced biocide susceptibility, but not antibiotic resistance, in K. pneumoniae clinical isolates.201222498639
227870.9907First detected OXA-50 carbapenem-resistant clinical isolates Pseudomonas aeruginosa from Bulgaria and interplay between the expression of main efflux pumps, OprD and intrinsic AmpC. Introduction. Carbapenems are often described as the most effective weapon against infections caused by multidrug-resistant bacteria especially those belonging to the group of non-fermenting bacteria such as Pseudomonas. The main mechanisms leading to resistance are the hyperexpression of certain efflux pumps belonging to the resisto-nodular division and the lower expression of the transmembrane porin OprD, sometimes in combination with excessive production of the intrinsic AmpC. Carbapenemases are assumed to play a secondary role.Aim. The aim of this study was to determine the exact mechanisms of carbapenem resistance in Pseudomonas aeruginosa isolates from the largest Bulgarian University hospital 'St. George'- Plovdiv.Methodology. A total of 32 clinical isolates collected from different patients' samples resistant to imipenem and/or meropenem were examined via phenotypic and molecular-genetic tests.Results. No metallo-enzyme production was detected. Three isolates were positive for OXA-50-encoding genes in two of them in combination with other oxacillinases or the bla (VEB-1) gene. For the first time, OXA-50-producing P. aeruginosa have been reported in Bulgaria. The increased expression or hyperexpression of MexXY-OprM efflux pump was observed as the main mechanism of resistance. In most cases, it was combined with lower expression or lack of OprD with or without MexAB-OprM hyperexpression. No excessive production of AmpC was detected in comparison to the reference ATCC 27853 P. aeruginosa strain.Conclusion. The increased expression or overexpression of MexXY-OprM efflux pumps is the leading cause of carbapenem resistance in our isolates Pseudomonas, detected in 94 % of the bacteria investigated.201931746726
578480.9907Identification and characterization of bacteria isolated from patients with cystic fibrosis in Jordan. BACKGROUND: Notable emergence of multidrug-resistant bacteria has become increasingly problematic worldwide. Most patients with cystic fibrosis (CF) suffer from chronic persistent infections with frequent occurrence of acute exacerbations. Routine screening of bacterial strains, epidemiological characteristics, and resistance patterns are particularly useful for patient management and maintenance of infection control procedures. METHODS: In this study, 43 pharyngeal samples were taken from patients with CF. Microbiological bacterial culture and identification, antimicrobial susceptibility testings, biofilm formation, including minimum biofilm eradication concentration (MBEC) and PCR for detecting resistance genes were performed. RESULTS: All samples were positive for bacterial growth. The predominant species were Staphylococcus aureus (41.86%; n = 18) and Pseudomonas aeruginosa (39.53%; n = 17). 30% of isolated bacteria were multidrug-resistant, resisting high concentrations of tested antibiotics. Among the 42 biofilm-forming isolates, 23.8% (n = 10) were strong biofilm formers. The occurance of resistance genes varied with blaKPC detected in 71% (n = 17) of all Gram-negative isolates and mecA found in 61% (n = 11) of all S. aureus strains. CONCLUSIONS: The majority of isolated bacteria were S. aureus and P. aeruginosa. The high frequency of antimicrobial resistance, the presence of resistance genes, and biofilm formation highlight the challenge in treatment and infection control measures in patients with CF.KEY MESSAGESStaphylococcus aureus and Pseudomonas aeruginosa are the most prevalent pathogens found in patients with CF in Jordan.Detection of antimicrobial resistance genes in patients with CF confirms that antimicrobial resistance patterns must always be monitored.Biofilm formation significantly increases the tolerance of bacteria to antimicrobial agents.202236264155
219490.9907Detection of Antiseptic-Resistance Genes in Pseudomonas and Acinetobacter spp. Isolated From Burn Patients. BACKGROUND: Quaternary ammonium compounds (QAC), which contain benzalkonium chloride as the most widely used agent, are employed as wound and skin antiseptics, as well as disinfectants in hospitals. The resistance mechanism to disinfectants is usually determine by genes which are related to resistance to quaternary ammonium compounds, namely, qacE, qacΔE1, qacΔE1 that are found in Gram-negative bacteria. OBJECTIVES: The aim of this study was to determine the incidence of antiseptic resistance genes, qacE and qacΔE1, in clinical isolates of Pseudomonas aeruginosa and Acinetobacter bumanii. MATERIALS AND METHODS: In this study, 83 clinical isolates of Pseudomonas aeruginosa, and 5 isolates of Acinetobacter baumannii from burn hospitals in Tehran and Isfahan provinces in 2010-2011, were tested by the PCR method. RESULTS: Out of the 83 clinical isolates of Pseudomonas aeruginosa, 49 isolates (50%) had the qacE gene, and 76 isolates (91.5%) had the qacΔE1 gene. In addition, in 5 isolates of Acinetobacter bumanii, 2 isolates (40%) had the qacE gene, and 4 isolates (80%) had the qacΔE1 gene. CONCLUSIONS: This study shows that the genes which harbored resistance to quaternary ammonium compound antiseptics are widespread among Pseudomonas aeruginosa and Acinetobacter bumanii isolates in burn patients.201424872941
2096100.9907Investigation of isepamicin in vitro efficiency in Gram negative bacteria efficacy of isepamicin. CONTEXT: Isepamicin is a new semisynthetic aminoglycoside derived from gentamicin B and it is effective against Gram negative bacteria. Antibiotic resistance is an emerging problem and new options need for the treatment of infections caused by Gram negative bacteria. AIMS: In this study we aimed to investigate the in vitro efficiency in carbapenem susceptible and nonsusceptible Enterobacterales and Pseudomonas aeruginosa. METHODS AND MATERIAL: A total of 214 isolates of Gram-negative bacteria (Enterobacterales n = 129 and P. aeruginosa n = 85). Identification of the bacteria was tested in Vitek MS (Biomeriux, France). Susceptibility of isepamicin, amikacin, gentamicin, tobramycin and netilmicin was determined by Kirby Bauer disc diffusion method. The breakpoints for susceptibility to isepamicin, amikacin, gentamicin, streptomycin, tobramycin and netilmicin were evaluated according to the Comité de l'Antibiogramme dela Société Française de Microbiologie (CA-SFM) and EUCAST, respectively. Aminoglycoside modifying enzyme (AME) genes were investigated by multiplex PCR method. RESULTS: Isepamicin susceptibility was determined as 92.3% for Enterobacterales and 67% for P. aeruginosa and 94.4% for carbapenem resistant Enterobacterales. The most common AME gene was aac (6')-Ib in both Enterobacterales (76%) and P. aeruginosa (14.1%). Seven of the isepamicin intermediate or resistant isolates were positive aac (6')-Ib in Enterobacterales and P. aeruginosa. CONCLUSIONS: In this study, isepamicin showed good efficiency against both susceptible and carbapenem nonsusceptible Enterobacterales. But amikacin was prior to isepamicin P. aeruginosa isolates. Isepamicin could be a therapeutic option for the infections caused by Enterobacterales.202133610258
2286110.9906Association of Antibacterial Susceptibility Profile with the Prevalence of Genes Encoding Efflux Proteins in the Bangladeshi Clinical Isolates of Staphylococcus aureus. Expelling antibiotic molecules out of the cell wall through multiple efflux pumps is one of the potential mechanisms of developing resistance against a wide number of antibiotics in Staphylococcus aureus. The aim of this study was to investigate the association between the antibiotic susceptibility profile and the prevalence of different efflux pump genes i.e., norA, norB, norC, mepA, sepA, mdeA, qacA/B, and smr in the clinical isolates of S. aureus. Sixty clinical isolates were collected from a tertiary level hospital in Bangladesh. The disc diffusion method using ten antibiotics of different classes was used to discern the susceptibility profile. polymerase chain reaction (PCR) was employed to observe the resistance patterns and to detect the presence of plasmid and chromosomal encoded genes. Among the clinical isolates, 60% (36 out of 60) of the samples were Methicillin-resistant Staphylococcus aureus (MRSA), whereas 55% (33 out of 60) of the bacterial samples were found to be multi-drug resistant. The bacteria showed higher resistance to vancomycin (73.33%), followed by ciprofloxacin (60%), cefixime (53.33%), azithromycin (43.33%), and amoxicillin (31.67%). The prevalence of the chromosomally-encoded efflux genes norA (91.67%), norB (90%), norC (93.33%), mepA (93.33%), sepA (98.33%), and mdeA (93.33%) were extremely high with a minor portion of them carrying the plasmid-encoded genes qacA/B (20%) and smr (8.33%). Several genetic combinations of efflux pump genes were revealed, among which norA + norB + norC + mepA + sepA + mdeA was the most widely distributed combination among MRSA and MSSA bacteria that conferred resistance against ciprofloxacin and probably vancomycin. Based on the present study, it is evident that the presence of multiple efflux genes potentiated the drug extrusion activity and may play a pivotal role in the development of multidrug resistance in S. aureus.202336830216
5383120.9906Draft genome sequence of Acinetobacter haemolyticus strain MUWRP1017 isolated from the pus of a female inpatient at Bwera General Hospital in Uganda. The bacterium Acinetobacter haemolyticus, with a genome size of 3.4 Mb, was isolated from a pus swab of a wound on the left lower limb above the ankle joint of a female patient. This strain carries the antimicrobial resistance genes cephalosporinase blaADC-25, oxallinase blaOXA-264, floR, and sul2 and other resistance and virulence genes.202439162454
2095130.9906In vitro activity of plazomicin against quinolone-resistant gram-negative bacteria isolated from catheter-associated urinary tract infections. Quinolone resistance among uropathogens is an increasing concern. Plazomicin is a new aminoglycoside that shows promising results against resistant bacteria. However, no study has yet tested its effect specifically on quinolone-resistant organisms. This study aimed to evaluate the in vitro activity of plazomicin and comparator drugs against quinolone-resistant Gram-negative isolates of catheter-associated urinary tract infections (CAUTI). Plazomicin demonstrated high inhibiting activity against Enterobacteriaceae isolates (95.9% at MIC≤ 2 mg/L), with MIC(50/90) was 1/2 mg/L. High MICs values were detected against non-Enterobacteriaceae isolates (MIC(50/90), 4/32 mg/L). Plazomicin had susceptibility rate of 97.2% against Enterobacteriaceae isolates carrying aminoglycosides modifying enzymes (AME) genes, while other aminoglycosides, amikacin and gentamicin showed reduced activity (32.4% and 25.4%, respectively). In conclusion, plazomicin showed potent in vitro activity against quinolone-resistant Enterobacteriaceae causing CAUTI, regardless of the AME pattern.202133810779
2160140.9906Detection of AdeAB, TetA, and TetB efflux pump genes in clinical isolates of tetracycline-resistant Acinetobacter baumannii from patients of Suez Canal University Hospitals. BACKGROUND: Acinetobacter baumannii is an opportunistic bacteria associated primarily with hospital-acquired infections. Its tendency to acquire or donate resistance genes to neighboring bacteria is a major concern. Tetracyclines have shown promise in treating A. baumannii infections, but tetracycline resistance is growing globally in A. baumannii isolates. OBJECTIVES: The study aimed to study (1) the prevalence of multidrug-resistant (MDR) A. baumannii infections at Suez Canal University Hospitals, (2) the distribution of efflux pump genes AdeA &B, TetA, and TetB, and (3) the effect of efflux pump inhibitor (CCCP) on tetracycline-resistant isolates. METHODS: Clinical samples (457) were collected (blood, urine, sputum, ETA, pus, and pleural fluid), followed by A. baumannii isolation and identification, PCR detection of efflux pump genes, and detection of tetracycline susceptibility and its MIC before and after treatment with the efflux pump inhibitor (CCCP). RESULTS: A total of 31 A. baumannii isolates were recovered (6.78%). The highest rate of isolation was from the ICU (48.3%) from the ET aspirate samples (48.3%). The efflux system AdeA and TetB genes were distributed in 100% of isolates, whereas AdeB was found in 93.5% of isolates and the TetA gene in 87.1% of isolates. All A. baumannii isolates were MDR showing resistance to three or more classes of antibiotics. 45% of the isolates showed a 4-fold reduction of MIC and 12.9% showed a 2-fold reduction in the MIC. CONCLUSIONS: Efflux pump is an important mechanism for tetracycline resistance among A. baumannii isolates.202539905304
5229150.9905Paradoxical High-Level Spiramycin Resistance and Erythromycin Susceptibility due to 23S rRNA Mutation in Streptococcus constellatus. Objectives: The aim of the study was to characterize phenotypically and genotypically an uncommon mechanism of resistance to macrolides, lincosamides, and streptogramins (MLS) in a Streptococcus milleri group clinical isolate. Materials and Methods: The isolate UCN96 was recovered from an osteoradionecrosis wound, and was identified using the matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and the partial sequencing of the sodA gene. Antimicrobial susceptibility testing were carried out by the disk diffusion method and minimal inhibitory concentrations (MICs) were determined by the broth microdilution technique. PCR screening was performed for MLS resistance genes described in Gram-positive bacteria. Specific mutations in the ribosomal proteins L3-, L4-, and L22-encoding genes were also screened and those in domain V of the 23S rRNA gene (rrl). The number of mutated copies of the rrl gene was determined using amplification-refractory mutation system quantitative-polymerase chain reaction (qPCR) analysis. Results: The clinical isolate UCN96 was unambiguously identified as Streptococcus constellatus. It was susceptible to all macrolides and lincosamides (ML) antibiotics except spiramycin (MIC >256 mg/L) while it was also resistant to streptogramins. Screening for all acquired resistance genes was negative and no mutation was found in genes coding for L3, L4, and L22 ribosomal proteins. Of interest, a single mutation, A2062C (according to Escherichia coli numbering), was detected in the domain V of 23S rRNA. Conclusion: Mutations at the position 2062 of 23S rRNA have been detected once in Streptococcus pneumoniae, and not yet in other Streptococcus spp. This mechanism is very likely uncommon in Gram-positive bacteria because different copies of 23S rRNA operons should be mutated for development of such a resistance pattern.202032031922
2187160.9905Multicentre investigation of pathogenic bacteria and antibiotic resistance genes in Chinese patients with acute exacerbation of chronic obstructive pulmonary disease. OBJECTIVE: A prospective observational study to investigate the distribution and antimicrobial resistance of pathogenic bacteria in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in Beijing, China. METHODS: Patients with AECOPD were recruited from 11 general hospitals. Sputum specimens were cultured and bacteria identified. Antibiotic susceptibility was determined for each isolate, and presence of antibiotic resistance genes was evaluated using polymerase chain reaction. RESULTS: Pathogenic bacteria were isolated from 109/318 patients (34.28%); 124 isolates of 22 pathogenic bacterial species were identified, including Klebsiella pneumoniae (16.94%), Pseudomonas aeruginosa (16.94%), Acinetobacter baumannii (11.29%), Streptococcus pneumoniae (8.87%), and Staphylococcus aureus (7.26%). S. aureus was sensitive to tigecycline, teicoplanin, vancomycin and linezolid but resistant to penicillin and levofloxacin. K.pneumoniae, P. aeruginosa, A. baumannii and E. coli were susceptible to amikacin and cefoperazone. CONCLUSIONS: K. pneumoniae and P. aeruginosa are the most common pathogenic bacteria in AECOPD cases in Beijing, China. Our antibiotic resistance findings may be helpful in selecting antibiotic therapy.201526152913
5416170.9905Limited predictive power of known resistance genes for phenotypic drug resistance in clinical Mycobacterium abscessus complex from Beijing in China. Mycobacterium abscessus complex (MABC) is an emerging pathogen with intrinsic multidrug resistance. Genomic sequencing technology has been widely applied to predict bacterial resistance in other bacteria, but the catalog of known resistance-determining genes to explain phenotypic resistance in the MABC is incomplete for many antibiotics. Eighty-one MABC strains were isolated from sputum samples of patients with pulmonary disease in the Beijing Chest Hospital. All isolates were tested for minimum inhibitory concentrations (MICs) to eight antibiotics and underwent whole-genome sequencing (WGS). Of the total 81 MABC isolates, six strains exhibited clarithromycin (CLM) resistance by day 3 in culture, but only one (16.7%, 1/6) contained a mutation in the rrl gene. All M. abscessus strains contained the erm (41)28T (100.0%, 49/49) polymorphism and exhibited CLM-induced resistance after 14 days in culture. Of the 61 imipenem-resistant strains, 12 (19.7%, 12/61) had mutations in the bla gene. Although there were four (4.9%) amikacin-resistant, nine (11.1%) linezolid-resistant, eight (9.9%) clofazimine-resistant, 23 (28.4%) bedaquiline-resistant, and 27 (33.3%) cefoxitin-resistant strains, no known mutations associated with resistance to these antibiotics were found. These results suggest that the explanatory power of known resistance genes for clinical MABC resistance is limited and that other unidentified genes or novel resistance mechanisms may be involved.202540422286
975180.9905Clonal diversity, antimicrobial resistance, and genome features among nonfermenting gram-negative bacteria isolated from patients with cystic fibrosis in Russia. Nonfermenting gram-negative (NFGN) bacteria were isolated from cystic fibrosis (CF) patients and subjected to susceptibility testing and whole-genome sequencing. Among 170 enrolled CF patients, 112 (65.9%) were colonized with at least 1 key NFGN species. The species-specific infection rate was highest for Pseudomonas aeruginosa (40.6%) followed by Stenotrophomonas maltophilia (14.1%), Achromobacter spp. (9.4%), and Burkholderia cepacia complex (Bcc, 8.2%) demonstrating a significant age-dependent increase for P. aeruginosa and Achromobacter spp., but not for S. maltophilia or Bcc. P. aeruginosa sequence types (STs) related to high-risk epidemic and global CF clones were carried by 12 (7.1%) and 13 (7.6%) patients, respectively. In total, 47% NFGN isolates, predominantly P. aeruginosa, harbored at least 1 plasmid-borne resistance gene; 5 ST235 isolates carried bla(VIM2). Pathogenicity island-borne virulence genes were harbored by 9% NFGN isolates. These findings in conjunction with frequent early colonization by Bcc raised serious concerns regarding infection control in Russian CF centers.202437984108
2161190.9905Detection of AcrA and AcrB Efflux Pumps in Multidrug-Resistant Klebsiella pneumonia that Isolated from Wounds Infection Patients in Al-Diwaniyah Province. Many infections produced by multidrug-resistant (MDR) Klebsiella pneumoniae are the main cause of death and treatment restrictions worldwide. In K. pneumoniae, the efflux pump system is dangerous in drug resistance. Therefore, this study was designed to investigate the involvement of the AcrA and AcrB efflux pumps in antibiotic resistance in Klebsiella pneumoniae isolated from wound patients. During June 2021-February 2022, 87 clinical isolates of Klebsiella pneumonia bacteria were obtained from wound samples patients consulted to the hospitals in AL-Diwaniyah province, Iraq. The disc diffusion method performed an antibiotic susceptibility test after microbiological/biochemical identification. The polymerase chain reaction (PCR) technique was used to examine efflux genes' prevalence (acrA and acrB). The results showed that resistance to Carbenicillin 72 (82.7%), Erythromycin 66 (75.8%), Rifampin 58 (66.6%), Ceftazidime 52 (59.7%), Cefotaxime 44 (50.5%), Novobiocin 38 (43.6%), Tetracycline 32 (36.7%), Ciprofloxacin 22 (25.2%), Gentamicin 16 (18.3%), Nitrofurantoin 6 (10.3%) in Klebsiella pneumoniae isolates. The PCR procedure revealed that the occurrence of the acrA and acrB genes is 55 (100%) and 55 (100%), respectively. The findings of this investigation show that the AcrA and AcrB efflux pumps play a crucial character in antibiotic resistance in multidrug-resistant Klebsiella pneumoniae bacterial isolates. As a result of the unintentional transmission of antimicrobial resistance genes, precise detection of resistance genes using molecular approaches is required to switch the extent of resistant strains.202337312720