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537600.9450In vitro Activity of Contezolid Against Methicillin-Resistant Staphylococcus aureus, Vancomycin-Resistant Enterococcus, and Strains With Linezolid Resistance Genes From China. Contezolid is a novel oxazolidinone, which exhibits potent activity against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and penicillin-resistant Streptococcus pneumoniae (PRSP). In this study, the in vitro activity of contezolid was compared with linezolid (LZD), tigecycline (TGC), teicoplanin (TEC), vancomycin (VA), daptomycin (DAP), and florfenicol (FFC) against MRSA and VRE strains isolated from China. Contezolid revealed considerable activity against MRSA and VRE isolates with MIC(90) values of 0.5 and 1.0 μg/mL, respectively. For VRE strains with different resistance genotypes, including vanA- and vanM-type strains, contezolid did not exhibit significantly differential antibacterial activity. Furthermore, the antimicrobial activity of contezolid is similar to or slightly better than that of linezolid against MRSA and VRE strains. Subsequently, the activity of contezolid was tested against strains carrying linezolid resistance genes, including Staphylococcus capitis carrying cfr gene and Enterococcus faecalis carrying optrA gene. The results showed that contezolid exhibited similar antimicrobial efficacy to linezolid against strains with linezolid resistance genes. In general, contezolid may have potential benefits to treat the infections caused by MRSA and VRE pathogens.202134489919
537510.9446Mechanism 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
537720.9439Synthetic lincosamides iboxamycin and cresomycin are active against ocular multidrug-resistant methicillin-resistant Staphylococcus aureus carrying erm genes. OBJECTIVE: Antimicrobial resistance is a global pandemic that poses a major threat to vision health as ocular bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA), are becoming increasingly resistant to first-line therapies. Here we evaluated the antimicrobial activity of new synthetic lincosamides in comparison to currently used antibiotics against clinical ocular MRSA isolates. METHODS: Antimicrobial susceptibility testing was performed by broth microdilution for two novel synthetic lincosamides (iboxamycin and cresomycin) and eight comparator antibiotics against a collection of 50 genomically characterised ocular MRSA isolates, including isolates harbouring erm genes (n = 25). RESULTS: Both drugs were active against widespread MRSA clonal complexes CC8 and CC5. The MIC(50) and MIC(90) of iboxamycin were 0.06 and 2 mg/L, respectively. Cresomycin (MIC(50) = 0.06 mg/L) also displayed good activity with an in vitro potency four-fold higher (MIC(90) = 0.5 mg/L) than iboxamycin. In isolates harbouring erm genes, MIC(90) were >16, 2, and 0.5 mg/L for clindamycin, iboxamycin, and cresomycin, respectively. The in vitro potencies of iboxamycin and cresomycin were similar or higher than that of comparator agents and were not impacted by multidrug-resistance phenotypes or by the presence of erm genes when compared with clindamycin. CONCLUSIONS: Our results demonstrate that iboxamycin and cresomycin display potent in vitro activity against ocular MRSA isolates, including multidrug-resistant isolates harbouring erm genes.202439293511
622430.9424Bacteriophage-resistant Staphylococcus aureus mutant confers broad immunity against staphylococcal infection in mice. In the presence of a bacteriophage (a bacteria-attacking virus) resistance is clearly beneficial to the bacteria. As expected in such conditions, resistant bacteria emerge rapidly. However, in the absence of the phage, resistant bacteria often display reduced fitness, compared to their sensitive counterparts. The present study explored the fitness cost associated with phage-resistance as an opportunity to isolate an attenuated strain of S. aureus. The phage-resistant strain A172 was isolated from the phage-sensitive strain A170 in the presence of the M(Sa) phage. Acquisition of phage-resistance altered several properties of A172, causing reduced growth rate, under-expression of numerous genes and production of capsular polysaccharide. In vivo, A172 modulated the transcription of the TNF-alpha, IFN-gamma and Il-1beta genes and, given intramuscularly, protected mice from a lethal dose of A170 (18/20). The heat-killed vaccine also afforded protection from heterologous methicillin-resistant S. aureus (MRSA) (8/10 mice) or vancomycin-intermediate S. aureus (VISA) (9/10 mice). The same vaccine was also effective when administered as an aerosol. Anti-A172 mouse antibodies, in the dose of 10 microl/mouse, protected the animals (10/10, in two independent experiments) from a lethal dose of A170. Consisting predominantly of the sugars glucose and galactose, the capsular polysaccharide of A172, given in the dose of 25 microg/mouse, also protected the mice (20/20) from a lethal dose of A170. The above results demonstrate that selection for phage-resistance can facilitate bacterial vaccine preparation.201020661301
580240.9423Dissecting vancomycin-intermediate resistance in staphylococcus aureus using genome-wide association. Vancomycin-intermediate Staphylococcus aureus (VISA) is currently defined as having minimal inhibitory concentration (MIC) of 4-8 µg/ml. VISA evolves through changes in multiple genetic loci with at least 16 candidate genes identified in clinical and in vitro-selected VISA strains. We report a whole-genome comparative analysis of 49 vancomycin-sensitive S. aureus and 26 VISA strains. Resistance to vancomycin was determined by broth microdilution, Etest, and population analysis profile-area under the curve (PAP-AUC). Genome-wide association studies (GWAS) of 55,977 single-nucleotide polymorphisms identified in one or more strains found one highly significant association (P = 8.78 E-08) between a nonsynonymous mutation at codon 481 (H481) of the rpoB gene and increased vancomycin MIC. Additionally, we used a database of public S. aureus genome sequences to identify rare mutations in candidate genes associated with VISA. On the basis of these data, we proposed a preliminary model called ECM+RMCG for the VISA phenotype as a benchmark for future efforts. The model predicted VISA based on the presence of a rare mutation in a set of candidate genes (walKR, vraSR, graSR, and agrA) and/or three previously experimentally verified mutations (including the rpoB H481 locus) with an accuracy of 81% and a sensitivity of 73%. Further, the level of resistance measured by both Etest and PAP-AUC regressed positively with the number of mutations present in a strain. This study demonstrated 1) the power of GWAS for identifying common genetic variants associated with antibiotic resistance in bacteria and 2) that rare mutations in candidate gene, identified using large genomic data sets, can also be associated with resistance phenotypes.201424787619
125450.9422Genetic diversity and antimicrobial resistance of Staphylococcus aureus from recurrent tonsillitis in children. The aim of this study was to analyze the prevalence of Staphylococcus aureus in the tonsils of children subjected tonsillectomy due to recurrent tonsilitis and to determine the spa types of the pathogens, carriage of virulence genes and antimicrobial resistance profiles. The study included 73 tonsillectomized children. Bacteria, including S. aureus were isolated from tonsillar surface prior to tonsillectomy, recovered from tonsillar core at the time of the surgery, and from posterior pharynx 2-4 weeks after the procedure. Staphylococcus aureus isolates were compared by spa typing, tested for antimicrobial susceptibility and for the presence of superantigenic toxin genes (sea-seu, eta, etb, tst, lukS/lukF-PV) by multiplex polymerase chain reaction. Seventy-three patients (mean 7.1 ± 4.1 years, 61.6% male) were assessed. The most commonly isolated bacteria were S. aureus. The largest proportion of staphylococcal isolates originated from tonsillar core (63%), followed by tonsillar surface (45.1%) and posterior pharynx in tonsillectomized children (18.2%, p = 0.007). Five (6.3%) isolates were identified as MRSA (mecA-positive). Up to 67.5% of the isolates synthesized penicillinases (blaZ-positive isolates), and 8.8% displayed MLS(B) resistance. The superantigenic toxin genes were detected in more than half of examined isolates (56.3%). spa types t091, t084, and t002, and clonal complexes (CCs) CC7, CC45, and CC30 turned out to be most common. Staphylococcus aureus associated with RT in children showed pathogenicity potential and considerable genetic diversity, and no clones were found to be specific for this condition although further studies are needed.202031692060
209560.9417In 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
517170.9416Adaptive laboratory-evolved MRSA with PPEF manifests cross-susceptibility to oxacillin and hypersensitivity to ciprofloxacin. Emerging resistance to current antibiotics is a global threat to human health. Therefore, comprehending the mechanism behind antibiotic resistance holds paramount importance. In the pursuit of finding new antibacterial agents, our group has developed a small molecule, PPEF (2'-(4-ethoxyphenyl)-5-(4-propylpiperazin-1-yl)-1H,1'H-2,5'-bibenzo(d)imidazole), having bisbenzimidazole as a pharmacophore, targeting bacterial type IA topoisomerase, a novel drug target in bacteria. We examined the emergence of mutations leading to PPEF resistance in laboratory-evolved Staphylococcus aureus strains. The growth curve revealed that S. aureus 25923 PPEF-resistant (SA-PR) and methicillin-resistant S. aureus 43300 PPEF-resistant (MRSA-PR) attained stationary phase earlier than their respective reference strains. RNA sequencing analysis revealed that atpD (ATP synthase gene) was downregulated by 2 log(2)-fold in both SA-PR and MRSA-PR strains, whereas there was 10 to 13 log(2)-fold downregulation of mecR1 (methicillin resistance-inducing gene), ble (bleomycin resistance-inducing gene), blaZ (beta-lactamase), pbp (penicillin-binding protein gene), ermA (rRNA adenine methyltransferase gene), and kdpB (potassium-transporting ATPase) in the MRSA-PR strain. Quantitative reverse-transcriptase PCR data confirmed these results. Additionally, MRSA-PR showed a 5 log(2)-fold upregulation of comG and a 9 log(2)-fold downregulation of topB, indicating increased genomic variability and stress adaptation contributing to resistance. Genomic sequencing revealed deletions of resistance genes, including aac(6')-aph(2''), aadD, mecA, and blaZ in MRSA-PR, resulting in a gain in resistance and a diminishing returns epistasis pattern in PPEF-evolved S. aureus strains. This led to the development of an evolved MRSA-PR strain susceptible to oxacillin, ciprofloxacin, gentamicin, and imipenem. Our findings indicate that adaptation to PPEF has increased antibiotic susceptibility, thereby changing the clinical outcomes of infections.IMPORTANCEThis study investigates how Staphylococcus aureus bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) strain, develop resistance to a new candidate antibacterial compound, PPEF (2'-(4-ethoxyphenyl)-5-(4-propylpiperazin-1-yl)-1H,1'H-2,5'-bibenzo(d)imidazole). The research found that resistant strains grew slower and showed significant changes in the activity of genes related to antibiotic resistance. Some resistance genes were deleted in the resistant MRSA strain, making it more sensitive to other antibiotics like oxacillin and ciprofloxacin. These findings highlight how resistance to PPEF leads to increased sensitivity to conventional antibiotics. This suggests that developing combination therapies of PPEF with other antibiotics could optimize treatment regimens and slow resistance evolution. This study also indicates that the antibiotic regimens could be designed to force resistant bacteria into evolutionary trade-offs, where they lose resistance to widely used antibiotics while gaining resistance to a new compound like PPEF.202540662666
125580.9416Emergence of quinupristin/dalfopristin resistance among livestock-associated Staphylococcus aureus ST9 clinical isolates. Quinupristin/dalfopristin (Q/D) is a valuable alternative to vancomycin for the treatment of meticillin-resistant Staphylococcus aureus (MRSA) infections. However, not long after Q/D was approved, bacteria with resistance to this newer antimicrobial agent were reported. To investigate the prevalence of Q/D resistance, a total of 1476 non-duplicate S. aureus isolates, including 775 MRSA, from a Chinese tertiary hospital were selected randomly from 2003 to 2013. Of the 775 MRSA, 3 (0.4%) were resistant to Q/D. All meticillin-susceptible S. aureus were susceptible to Q/D. The prevalence of Q/D resistance among S. aureus was 0.2% (3/1476). The three isolates with Q/D resistance had the same antimicrobial resistance profile, except for cefaclor and chloramphenicol. All three Q/D-resistant MRSA were positive for five streptogramin B resistance genes (ermA, ermB, ermC, msrA and msrB) and two streptogramin A resistance genes (vatC and vgaA) as determined by PCR and DNA sequencing. MRSA WZ1031 belonged to ST9-MRSA-SCCmecV-t899, whilst MRSA WZ414 and WZ480 belonged to ST9-MRSA-SCCmecNT(non-typeable)-t899. ST9 has been reported predominantly in livestock-associated (LA) MRSA in some Asian countries. The three patients with these MRSA isolates were not livestock handlers and did not keep close contact with livestock. The origin of these important LA-MRSA isolates causing human infections is not known. Taken together, Q/D resistance, which was caused by a combination of ermA-ermB-ermC-msrA-msrB-vatC-vgaA, was first found among S. aureus clinical isolates in China. The present study is the first report of the emergence of human infections caused by ST9 LA-MRSA isolates with Q/D resistance.201425218154
234290.9411Correlation Analysis of Staphylococcus aureus Drug Resistance and Virulence Factors with Blood Cell Counts and Coagulation Indexes. OBJECTIVE: The influence of different Staphylococcus aureus variants on blood cells and coagulation system was evaluated by investigating the carrying status of drug resistance genes and virulence genes of methicillin-resistantStaphylococcus aureus (MRSA) and methicillin-sensitiveStaphylococcus aureus (MSSA). METHODS: A total of 105 blood culture-derivedStaphylococcus aureus strains were collected. The carrying status of drug resistance genes mecA and three virulence genes tst, pvl, and sasX was analyzed by polymerase chain reaction (PCR). The changes in routine blood routine counts and coagulation indexes of patients infected with different strains were analyzed. RESULTS: The results showed that the positive rate of mecA was consistent with that of MRSA. Virulence genes tst and sasX were detected only in MRSA. Compared with MSSA, patients infected with MRSA or MSSA patients infected with virulence factor, leukocyte count and neutrophil count in peripheral blood were significantly increased, and the platelet count decreased to a higher degree. Part thromboplastin time increased, D-dimer increased, but fibrinogen content decreased more. The changes of erythrocyte and hemoglobin had no significant correlation with whether Staphylococcus aureus carried virulence genes. CONCLUSION: The detection rate of MRSA in patients with positive Staphylococcus aureus in blood culture had exceeded 20%. The detected MRSA bacteria carried three virulence genes, tst, pvl, and sasX, which were more likely than MSSA. MRSA, which carries two virulence genes, is more likely to cause clotting disorders.202336846497
1483100.9409Clinical Evaluation of the iCubate iC-GPC Assay for Detection of Gram-Positive Bacteria and Resistance Markers from Positive Blood Cultures. The iC-GPC Assay (iCubate, Huntsville, AL) is a qualitative multiplex test for the detection of five of the most common Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, and Enterococcus faecium) responsible for bacterial bloodstream infections, performed directly from positive blood cultures. The assay also detects the presence of the mecA, vanA, and vanB resistance determinants. This study comparatively evaluated the performance of the iC-GPC Assay against the Verigene Gram-positive blood culture (BC-GP) assay (Luminex Corp., Austin, TX) for 1,134 patient blood culture specimens positive for Gram-positive cocci. The iC-GPC Assay had an overall percent agreement with the BC-GP assay of 95.5%. Discordant specimens were further analyzed by PCR and a bidirectional sequencing method. The results indicate that the iC-GPC Assay together with the iCubate system is an accurate and reliable tool for the detection of the five most common Gram-positive bacteria and their resistance markers responsible for bloodstream infections.201829899000
808110.9407Exposure of Legionella pneumophila to low-shear modeled microgravity: impact on stress response, membrane lipid composition, pathogenicity to macrophages and interrelated genes expression. Here, we studied the effect of low-shear modeled microgravity (LSMMG) on cross stress resistance (heat, acid, and oxidative), fatty acid content, and pathogenicity along with alteration in expression of stress-/virulence-associated genes in Legionella pneumophila. The stress resistance analysis result indicated that bacteria cultivated under LSMMG environments showed higher resistance with elevated D-values at 55 °C and in 1 mM of hydrogen peroxide (H(2)O(2)) conditions compared to normal gravity (NG)-grown bacteria. On the other hand, there was no significant difference in tolerance (p < 0.05) toward simulated gastric fluid (pH-2.5) acid conditions. In fatty acid analysis, our result showed that a total amount of saturated and cyclic fatty acids was increased in LSMMG-grown cells; as a consequence, they might possess low membrane fluidity. An upregulated expression level was noticed for stress-related genes (hslV, htrA, grpE, groL, htpG, clpB, clpX, dnaJ, dnaK, rpoH, rpoE, rpoS, kaiB, kaiC, lpp1114, ahpC1, ahpC2, ahpD, grlA, and gst) under LSMMG conditions. The reduced virulence (less intracellular bacteria and less % of induce apoptosis in RAW 264.7 macrophages) of L. pneumophila under LSMMG conditions may be because of downregulation related genes (dotA, dotB, dotC, dotD, dotG, dotH, dotL, dotM, dotN, icmK, icmB, icmS, icmT, icmW, ladC, rtxA, letA, rpoN, fleQ, fleR, and fliA). In the LSMMG group, the expression of inflammation-related factors, such as IL-1α, TNF-α, IL-6, and IL-8, was observed to be reduced in infected macrophages. Also, scanning electron microscopy (SEM) analysis showed less number of LSMMG-cultivated bacteria attached to the host macrophages compared to NG. Thus, our study provides understandings about the changes in lipid composition and different genes expression due to LSMMG conditions, which apparently influence the alterations of L. pneumophila' stress/virulence response.202438305908
2375120.9406Prevalence of inducible clindamycin resistance in methicillin-resistant Staphylococcus aureus: the first study in Jordan. INTRODUCTION: A high rate of infections with methicillin-resistant Staphylococcus aureus (MRSA) has been documented, in both hospital- (HA-MRSA) and community-acquired (CA-MRSA) diseases in Jordan. Erythromycin and clindamycin are considered treatments of choice. However, resistance to erythromycin with false susceptibility to clindamycin in vitro may lead to therapeutic failure. Hence, it is mandatory to study the prevalence of inducible resistance to macrolide-lincosamide-streptogramin B (iMLSB) antibiotics conferred by erm genes in those bacteria. METHODOLOGY: S. aureus isolates were identified morphologically and biochemically, and MRSA were appraised using standard procedures. Induction in resistance to MLSB antibiotics among MRSA isolates was detected phenotypically using the D-test, and the presence of erm genes was revealed by polymerase chain reaction (PCR). RESULTS: Of 126 collected Staphylococcus isolates, 71 (56.3%) isolates were S. aureus, of which 55 (77.5%) were MRSA. A total of 43 (78.2%) MRSA-discordant isolates were resistant to erythromycin, of which 33 (76.7%) exhibited the iMLSB (D-test positive), 2 (4.7%) the MSB (D-test negative), and 8 (18.6%) the constitutive resistant (cMLSB) phenotypes. Induction of clindamycin resistance was 1.6 times greater in CA-MRSA than in HA-MRSA. Furthermore, ermA and ermC were significantly prevalent in HA-MRSA and CA-MRSA, respectively. CONCLUSIONS: Continuous surveillance of the MLSB resistance is important and required before the prescription of clindamycin to treat MRSA infections.201728459227
3740130.9405Stp1 Loss of Function Promotes β-Lactam Resistance in Staphylococcus aureus That Is Independent of Classical Genes. β-Lactam resistance in Staphylococcus aureus limits treatment options. Stp1 and Stk1, a serine-threonine phosphatase and kinase, respectively, mediate serine-threonine kinase (STK) signaling. Loss-of-function point mutations in stp1 were detected among laboratory-passaged β-lactam-resistant S. aureus strains lacking mecA and blaZ, the major determinants of β-lactam resistance in the bacteria. Loss of Stp1 function facilitates β-lactam resistance of the bacteria.202032179529
2352140.9403Phenotypic and Molecular Detection of Biofilm Formation in Methicillin-Resistant Staphylococcus Aureus Isolated from Different Clinical Sources in Erbil City. BACKGROUND: Staphylococcus aureus is an important causative pathogen. The production of biofilms is an important factor and makes these bacteria resistant to antimicrobial therapy. OBJECTIVES: the current study aimed to assess the prevalence of resistance to antibacterial agents and to evaluate the phenotypic and genotypic characterization of biofilm formation among S. aureus strains. METHODS: This study included 50 isolates of Methicillin-resistant S. aureus (MRSA) and Methicillin-Susceptible S. aureus (MSSA). S. aureus was identified by molecular and conventional methods, and antimicrobial resistance was tested with a disc diffusion method. The biofilm formation was performed through the Microtiter plate method. Strains were subjected to PCR to determine the presence of nuc, mecA, icaA, icaB, icaC, and icaD genes. RESULTS: Of the 50 S. aureus isolates, 32(64%) and 18(36%) were MRSA and MSSA, respectively. A large number of MRSA and MSSA isolates showed resistance to Penicillin and Azithromycin, and a lower number of MRSA and MSSA isolates showed resistance to Amikacin Gentamicin. None of the isolates was resistant to Vancomycin. The MRSA strains had significantly higher resistance against antibiotics than MSSA strains (P = 0.0154). All isolates (MRSA and MSSA) were able to produce biofilm with levels ranging from strong (31.25 %), (16.6%) to moderate (53.12%), (50%) to weak (15.6%), (33.3%) respectively. The MRSA strains had a significantly higher biofilm formation ability than the MSSA strains (P = 0.0079). The biofilm-encoding genes were detected among isolates with different frequencies. The majority of S. aureus isolates, 42 (84%), were positive for the icaA. The prevalence rates of the icaB, icaC and icaD genes were found to be 37 (74%), 40 (80%) and 41 (82%), respectively. CONCLUSIONS: The prevalence of biofilm encoding genes associated with multidrug resistance in S. aureus strains is high. Therefore, identifying epidemiology, molecular characteristics, and biofilm management of S. aureus infection would be helpful.202336908866
5378150.9402Genome-Wide Analysis of Staphylococcus aureus Sequence Type 72 Isolates Provides Insights Into Resistance Against Antimicrobial Agents and Virulence Potential. Staphylococcus aureus sequence type 72 (ST72) is a major community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) that has rapidly entered the hospital setting in Korea, causing mild superficial skin wounds to severe bloodstream infections. In this study, we sequenced and analyzed the genomes of one methicillin-resistant human isolate and one methicillin-sensitive human isolate of ST72 from Korea, K07-204 and K07-561, respectively. We used a subtractive genomics approach to compare these two isolates to other 27 ST72 isolates to investigate antimicrobial resistance (AMR) and virulence potential. Furthermore, we validated genotypic differences by phenotypic characteristics analysis. Comparative and subtractive genomics analysis revealed that K07-204 contains methicillin (mecA), ampicillin (blaZ), erythromycin (ermC), aminoglycoside (aadD), and tetracycline (tet38, tetracycline efflux pump) resistance genes while K07-561 has ampicillin (blaZ) and tetracycline (tet38) resistance genes. In addition to antibiotics, K07-204 was reported to show resistance to lysostaphin treatment. K07-204 also has additional virulence genes (adsA, aur, hysA, icaABCDR, lip, lukD, sdrC, and sdrE) compared to K07-561, which may explain the differential virulence potential of these human isolates of ST72. Unexpectedly, the virulence potential of K07-561 was higher in an in vivo wax-worm infection model than that of K07-204, putatively due to the presence of a 20-fold higher staphyloxanthin concentration than K07-204. Comprehensive genomic analysis of these two human isolates, with 27 ST72 isolates, and S. aureus USA300 (ST8) suggested that acquisition of both virulence and antibiotics resistance genes by ST72 isolates might have facilitated their adaptation from a community to a hospital setting where the selective pressure imposed by antibiotics selects for more resistant and virulent isolates. Taken together, the results of the current study provide insight into the genotypic and phenotypic features of various ST72 clones across the globe, delivering more options for developing therapeutics and rapid molecular diagnostic tools to detect resistant bacteria.202033552024
828160.9401Screening for Resistant Bacteria, Antimicrobial Resistance Genes, Sexually Transmitted Infections and Schistosoma spp. in Tissue Samples from Predominantly Vaginally Delivered Placentae in Ivory Coast and Ghana. Medical complications during pregnancy have been frequently reported from Western Africa with a particular importance of infectious complications. Placental tissue can either become the target of infectious agents itself, such as, e.g., in the case of urogenital schistosomiasis, or be subjected to contamination with colonizing or infection-associated microorganisms of the cervix or the vagina during vaginal delivery. In the retrospective cross-sectional assessment presented here, the quantitative dimension of infection or colonization with selected resistant or pathogenic bacteria and parasites was regionally assessed. To do so, 274 collected placental tissues from Ivory Coastal and Ghanaian women were subjected to selective growth of resistant bacteria, as well as to molecular screening for beta-lactamase genes, Schistosoma spp. and selected bacterial causative agents of sexually transmitted infections (STI). Panton-Valentine-negative methicillin-resistant Staphylococcus aureus (MRSA) was grown from 1.8% of the tissue samples, comprising the spa types t008 and t688, as well as the newly detected ones, t12101 (n = 2) and t12102. While the culture-based recovery of resistant Enterobacterales and nonfermentative rod-shaped Gram-negative bacteria failed, molecular assessments confirmed beta-lactamase genes in 31.0% of the samples with multiple detections of up to four resistance genes per sample and bla(CTX-M), bla(IMP), bla(GES), bla(VIM), bla(OXA-58)-like, bla(NDM), bla(OXA-23)-like, bla(OXA-48)-like and bla(KPC) occurring in descending order of frequency. The beta-lactamase genes bla(OXA-40/24)-like, bla(NMC_A/IMI), bla(BIC), bla(SME), bla(GIM) and bla(DIM) were not detected. DNA of the urogenital schistosomiasis-associated Schistosoma haematobium complex was recorded in 18.6% of the samples, but only a single positive signal for S. mansoni with a high cycle-threshold value in real-time PCR was found. Of note, higher rates of schistosomiasis were observed in Ghana (54.9% vs. 10.3% in Ivory Coast) and Cesarean section was much more frequent in schistosomiasis patients (61.9% vs. 14.8% in women without Schistosoma spp. DNA in the placenta). Nucleic acid sequences of nonlymphogranuloma-venereum-associated Chlamydia trachomatis and of Neisseria gonorrhoeae were recorded in 1.1% and 1.9% of the samples, respectively, while molecular attempts to diagnose Treponema pallidum and Mycoplasma genitalium did not lead to positive results. Molecular detection of Schistosoma spp. or STI-associated pathogens was only exceptionally associated with multiple resistance gene detections in the same sample, suggesting epidemiological distinctness. In conclusion, the assessment confirmed considerable prevalence of urogenital schistosomiasis and resistant bacterial colonization, as well as a regionally expected abundance of STI-associated pathogens. Continuous screening offers seem advisable to minimize the risks for the pregnant women and their newborns.202337623959
1475170.9400Evaluation of the FilmArray(®) Pneumonia Plus Panel for Rapid Diagnosis of Hospital-Acquired Pneumonia in Intensive Care Unit Patients. The FilmArray(®) Pneumonia plus Panel (FAPP) is a new multiplex molecular test for hospital-acquired pneumonia (HAP), which can rapidly detect 18 bacteria, 9 viruses, and 7 resistance genes. We aimed to compare the diagnosis performance of FAPP with conventional testing in 100 intensive care unit (ICU) patients who required mechanical ventilation, with clinically suspected HAP. A total of 237 samples [76 bronchoalveolar lavages (BAL(DS)) and 82 endotracheal aspirates (ETA(DS)) obtained at HAP diagnosis, and 79 ETA obtained during follow-up (ETA(TT))], were analyzed independently by routine microbiology testing and FAPP. 58 patients had paired BAL(DS) and ETA(DS). The positivity thresholds of semi-quantified bacteria were 10(3)-10(4) CFUs/mL or 10(4) copies/mL for BAL, and 10(5) CFUs/mL or copies/mL for ETA. Respiratory commensals (H. influenzae, S. aureus, E. coli, S. pneumoniae) were the most common pathogens. Discordant results for bacterial identification were observed in 33/76 (43.4%) BAL(DS) and 36/82 (43.9%) ETA(DS), and in most cases, FAPP identified one supplemental bacteria (23/33 BAL(DS) and 21/36 ETA(DS)). An absence of growth, or polybacterial cultures, explained almost equally the majority of the non-detections in culture. No linear relationship was observed between bin and CFUs/mL variables. Concordant results between paired BAL(DS) and ETA(DS) were obtained in 46/58 (79.3%) patients with FAPP. One of the 17 resistance genes detected with FAPP (mecA/C and MREJ) was not confirmed by conventional testing. Overall, FAPP enhanced the positivity rate of diagnostic testing, with increased recognition of coinfections. Implementing this strategy may allow clinicians to make more timely and informed decisions.202032983057
6223180.9398Bicarbonate induces high-level resistance to the human antimicrobial peptide LL-37 in Staphylococcus aureus small colony variants. OBJECTIVES: Staphylococcus aureus small colony variants (SCVs) cause persistent infections and are resistant to cationic antibiotics. Antimicrobial peptides (AMPs) have been suggested as promising alternatives for treating antibiotic-resistant bacteria. We investigated the capacity of the human cationic AMP LL-37 to kill SCVs in the presence of physiological concentrations of bicarbonate, which are reported to alter bacterial membrane permeability and change resistance of bacteria to AMPs. METHODS: MBCs of LL-37 for S. aureus SCVs with mutations in different genes in the presence and absence of bicarbonate were determined. RESULTS: In the absence of bicarbonate, SCVs of S. aureus strains LS-1 and 8325-4 had the same level of resistance to LL-37 as the parental strain (8 mg/L). In the presence of bicarbonate, hemB, menD and aroD SCVs of LS-1 had high-level resistance to LL-37 (≥128 mg/L) compared with the parental strain (16 mg/L). However, only the aroD SCV of strain 8324-5 showed high-level resistance. 8325-4 harbours mutations in two genes, tcaR and rsbU, which are involved in antimicrobial sensing and the stress response, respectively. When rsbU was repaired in 8325-4 it displayed high-level resistance to LL-37 in the presence of bicarbonate. This phenotype was lost when tcaR was also repaired, demonstrating that RsbU and TcaR are involved in LL-37 resistance in the presence of bicarbonate. CONCLUSIONS: S. aureus SCVs would be resistant to high concentrations of LL-37 in niches where there are physiological concentrations of bicarbonate and therefore this AMP may not be effective in combating SCVs.201829211886
2097190.9396Effective Photodynamic Therapy with Ir(III) for Virulent Clinical Isolates of Extended-Spectrum Beta-Lactamase Klebsiella pneumoniae. BACKGROUND: The extended-spectrum beta-lactamase (ESBL) Klebsiella pneumoniae is one of the leading causes of health-associated infections (HAIs), whose antibiotic treatments have been severely reduced. Moreover, HAI bacteria may harbor pathogenic factors such as siderophores, enzymes, or capsules, which increase the virulence of these strains. Thus, new therapies, such as antimicrobial photodynamic inactivation (aPDI), are needed. METHOD: A collection of 118 clinical isolates of K. pneumoniae was characterized by susceptibility and virulence through the determination of the minimum inhibitory concentration (MIC) of amikacin (Amk), cefotaxime (Cfx), ceftazidime (Cfz), imipenem (Imp), meropenem (Mer), and piperacillin-tazobactam (Pip-Taz); and, by PCR, the frequency of the virulence genes K2, magA, rmpA, entB, ybtS, and allS. Susceptibility to innate immunity, such as human serum, macrophages, and polymorphonuclear cells, was tested. All the strains were tested for sensitivity to the photosensitizer PSIR-3 (4 µg/mL) in a 17 µW/cm(2) for 30 min aPDI. RESULTS: A significantly higher frequency of virulence genes in ESBL than non-ESBL bacteria was observed. The isolates of the genotype K2+, ybtS+, and allS+ display enhanced virulence, since they showed higher resistance to human serum, as well as to phagocytosis. All strains are susceptible to the aPDI with PSIR-3 decreasing viability in 3log10. The combined treatment with Cfx improved the aPDI to 6log10 for the ESBL strains. The combined treatment is synergistic, as it showed a fractional inhibitory concentration (FIC) index value of 0.15. CONCLUSIONS: The aPDI effectively inhibits clinical isolates of K. pneumoniae, including the riskier strains of ESBL-producing bacteria and the K2+, ybtS+, and allS+ genotype. The aPDI with PSIR-3 is synergistic with Cfx.202133922077