Solithromycin Inhibition of Protein Synthesis and Ribosome Biogenesis in Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae

ABSTRACTThe continuing increase in antibiotic-resistant microorganisms is driving the search for new antibiotic targets and improved antimicrobial agents. Ketolides are semisynthetic derivatives of macrolide antibiotics, which are effective against certain resistant organisms. Solithromycin (CEM-101) is a novel fluoroketolide with improved antimicrobial effectiveness. This compound binds to the large 50S subunit of the ribosome and inhibits protein biosynthesis. Like other ketolides, it should impair bacterial ribosomal subunit formation. This mechanism of action was examined in strains ofStreptococcus pneumoniae,Staphylococcus aureus, andHaemophilus influenzae. The mean 50% inhibitory concentrations (IC50s) for solithromycin inhibition of cell viability, protein synthesis, and growth rate were 7.5, 40, and 125 ng/ml forStreptococcus pneumoniae,Staphylococcus aureus, andHaemophilus influenzae, respectively. The net formation of the 50S subunit was reduced in all three organisms, with IC50s similar to those given above. The rates of 50S subunit formation measured by a pulse-chase labeling procedure were reduced by 75% in cells growing at the IC50of solithromycin. Turnover of 23S rRNA was stimulated by solithromycin as well. Solithromycin was found to be a particularly effective antimicrobial agent, with IC50s comparable to those of telithromycin and significantly better than those of azithromycin and clarithromycin in these three microorganisms.

Download Full-text

Retapamulin Inhibition of Translation and 50S Ribosomal Subunit Formation in Staphylococcus aureus Cells

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00475-07 ◽

2007 ◽

Vol 51 (9) ◽

pp. 3385-3387 ◽

Cited By ~ 18

Author(s):

W. Scott Champney ◽

Ward K. Rodgers

Keyword(s):

Staphylococcus Aureus ◽

16S Rrna ◽

Cell Viability ◽

Protein Biosynthesis ◽

Ribosomal Subunit ◽

Inhibitory Effect ◽

23S Rrna ◽

Specific Inhibition ◽

Methicillin Resistant

ABSTRACT Retapamulin inhibited protein biosynthesis and cell viability in methicillin-sensitive and methicillin-resistant Staphylococcus aureus organisms. A specific inhibitory effect on 50S ribosomal subunit formation was also found. Pulse-chase labeling experiments confirmed the specific inhibition of 50S subunit biogenesis. Turnover of 23S rRNA was found, with no effect on 16S rRNA amounts.

Download Full-text

Linezolid-Resistant Staphylococcus aureus Strain 1128105, the First Known Clinical Isolate Possessing thecfrMultidrug Resistance Gene

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03493-14 ◽

2014 ◽

Vol 58 (11) ◽

pp. 6592-6598 ◽

Cited By ~ 17

Author(s):

Jeffrey B. Locke ◽

Douglas E. Zuill ◽

Caitlyn R. Scharn ◽

Jennifer Deane ◽

Daniel F. Sahm ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Resistance Gene ◽

Ribosomal Subunit ◽

Single Copy ◽

Aureus Strain ◽

23S Rrna ◽

Surveillance Program ◽

Rrna Gene ◽

Multidrug Resistance Gene ◽

Content Type

ABSTRACTThe Cfr methyltransferase confers resistance to six classes of drugs which target the peptidyl transferase center of the 50S ribosomal subunit, including some oxazolidinones, such as linezolid (LZD). The mobilecfrgene was identified in European veterinary isolates from the late 1990s, although the earliest report of a clinicalcfr-positive strain was the 2005 Colombian methicillin-resistantStaphylococcus aureus(MRSA) isolate CM05. Here, through retrospective analysis of LZDrclinical strains from a U.S. surveillance program, we identified acfr-positive MRSA isolate, 1128105, from January 2005, predating CM05 by 5 months. Molecular typing of 1128105 revealed a unique pulsed-field gel electrophoresis (PFGE) profile most similar to that of USA100,spatype t002, and multilocus sequence type 5 (ST5). In addition tocfr, LZD resistance in 1128105 is partially attributed to the presence of a single copy of the 23S rRNA gene mutation T2500A. Transformation of the ∼37-kb conjugative p1128105cfr-bearing plasmid from 1128105 intoS. aureusATCC 29213 background strains was successful in recapitulating the Cfr antibiogram, as well as resistance to aminoglycosides and trimethoprim. A 7-kbcfr-containing region of p1128105 possessed sequence nearly identical to that found in the Chinese veterinaryProteus vulgarisisolate PV-01 and in U.S. clinicalS. aureusisolate 1900, although the presence of IS431-like sequences is unique to p1128105. Thecfrgene environment in this early clinicalcfr-positive isolate has now been identified in Gram-positive and Gram-negative strains of clinical and veterinary origin and has been associated with multiple mobile elements, highlighting the versatility of this multidrug resistance gene and its potential for further dissemination.

Download Full-text

Linezolid Surveillance Results for the United States (LEADER Surveillance Program 2014)

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02803-15 ◽

2016 ◽

Vol 60 (4) ◽

pp. 2273-2280 ◽

Cited By ~ 51

Author(s):

Robert K. Flamm ◽

Rodrigo E. Mendes ◽

Patricia A. Hogan ◽

Jennifer M. Streit ◽

James E. Ross ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Streptococcus Pneumoniae ◽

Ribosomal Proteins ◽

The United States ◽

23S Rrna ◽

Surveillance Program ◽

Coagulase Negative Staphylococci ◽

Content Type ◽

Mrsa Strains ◽

Viridans Group Streptococci

ABSTRACTThelinezolidexperience andaccuratedetermination ofresistance (LEADER) surveillance program has monitored linezolid activity, spectrum, and resistance since 2004. In 2014, a total of 6,865 Gram-positive pathogens from 60 medical centers from 36 states were submitted. The organism groups evaluated wereStaphylococcus aureus(3,106), coagulase-negative staphylococci (CoNS; 797), enterococci (855),Streptococcus pneumoniae(874), viridans group streptococci (359), and beta-hemolytic streptococci (874). Susceptibility testing was performed by reference broth microdilution at the monitoring laboratory. Linezolid-resistant isolates were confirmed by repeat testing. PCR and sequencing were performed to detect mutations in 23S rRNA, L3, L4, and L22 proteins and acquired genes (cfrandoptrA). The MIC50/90forStaphylococcus aureuswas 1/1 μg/ml, with 47.2% of isolates being methicillin-resistantStaphylococcus aureus. Linezolid was active against allStreptococcus pneumoniaestrains and beta-hemolytic streptococci with a MIC50/90of 1/1 μg/ml and against viridans group streptococci with a MIC50/90of 0.5/1 μg/ml. Among the linezolid-nonsusceptible MRSA strains, one strain harboredcfronly (MIC, 4 μg/ml), one harbored G2576T (MIC, 8 μg/ml), and one containedcfrand G2576T with L3 changes (MIC, ≥8 μg/ml). Among CoNS, 0.75% (six isolates) of all strains demonstrated linezolid MIC results of ≥4 μg/ml. Five of these were identified asStaphylococcus epidermidis, four of which containedcfrin addition to the presence of mutations in the ribosomal proteins L3 and L4, alone or in combination with 23S rRNA (G2576T) mutations. Six enterococci (0.7%) were linezolid nonsusceptible (≥4 μg/ml; five with G2576T mutations, including one with an additionalcfrgene, and one strain withoptrAonly). Linezolid demonstrated excellent activity and a sustained susceptibility rate of 99.78% overall.

Download Full-text

Pharmacokinetics/Pharmacodynamics of Peptide Deformylase Inhibitor GSK1322322 against Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus in Rodent Models of Infection

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01842-15 ◽

2015 ◽

Vol 60 (1) ◽

pp. 180-189 ◽

Cited By ~ 7

Author(s):

Jennifer Hoover ◽

Thomas Lewandowski ◽

Robert J. Straub ◽

Steven J. Novick ◽

Peter DeMarsh ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Streptococcus Pneumoniae ◽

Haemophilus Influenzae ◽

Lung Model ◽

Peptide Deformylase ◽

Dose Fractionation ◽

Mouse Lung ◽

Time Curve ◽

Content Type

ABSTRACTGSK1322322 is a novel inhibitor of peptide deformylase (PDF) with goodin vitroactivity against bacteria associated with community-acquired pneumonia and skin infections. We have characterized thein vivopharmacodynamics (PD) of GSK1322322 in immunocompetent animal models of infection withStreptococcus pneumoniaeandHaemophilus influenzae(mouse lung model) and withStaphylococcus aureus(rat abscess model) and determined the pharmacokinetic (PK)/PD index that best correlates with efficacy and its magnitude. Oral PK studies with both models showed slightly higher-than-dose-proportional exposure, with 3-fold increases in area under the concentration-time curve (AUC) with doubling doses. GSK1322322 exhibited dose-dependentin vivoefficacy against multiple isolates ofS. pneumoniae,H. influenzae, andS. aureus. Dose fractionation studies with twoS. pneumoniaeandS. aureusisolates showed that therapeutic outcome correlated best with the free AUC/MIC (fAUC/MIC) index inS. pneumoniae(R2, 0.83), whereasfAUC/MIC and free maximum drug concentration (fCmax)/MIC were the best efficacy predictors forS. aureus(R2, 0.9 and 0.91, respectively). Median dailyfAUC/MIC values required for stasis and for a 1-log10reduction in bacterial burden were 8.1 and 14.4 for 11S. pneumoniaeisolates (R2, 0.62) and 7.2 and 13.0 for fiveH. influenzaeisolates (R2, 0.93). The data showed that for eightS. aureusisolates,fAUC correlated better with efficacy thanfAUC/MIC (R2, 0.91 and 0.76, respectively), as efficacious AUCs were similar for all isolates, independent of their GSK1322322 MIC (range, 0.5 to 4 μg/ml). MedianfAUCs of 2.1 and 6.3 μg · h/ml were associated with stasis and 1-log10reductions, respectively, forS. aureus.

Download Full-text

Impact of Intermittent Preventive Treatment in Pregnancy with Azithromycin-Containing Regimens on Maternal Nasopharyngeal Carriage and Antibiotic Sensitivity of Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus: a Cross-Sectional Survey at Delivery

Journal of Clinical Microbiology ◽

10.1128/jcm.03570-14 ◽

2015 ◽

Vol 53 (4) ◽

pp. 1317-1323 ◽

Cited By ~ 4

Author(s):

Holger W. Unger ◽

Celestine Aho ◽

Maria Ome-Kaius ◽

Regina A. Wangnapi ◽

Alexandra J. Umbers ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Streptococcus Pneumoniae ◽

Haemophilus Influenzae ◽

Antibiotic Susceptibility ◽

Intermittent Preventive Treatment ◽

Preventive Treatment ◽

Resistant Bacteria ◽

Nasopharyngeal Carriage ◽

Content Type ◽

In Pregnancy

Sulfadoxine-pyrimethamine (SP) plus azithromycin (AZ) (SPAZ) has the potential for intermittent preventive treatment of malaria in pregnancy (IPTp), but its use could increase circulation of antibiotic-resistant bacteria associated with severe pediatric infections. We evaluated the effect of monthly SPAZ-IPTp compared to a single course of SP plus chloroquine (SPCQ) on maternal nasopharyngeal carriage and antibiotic susceptibility ofStreptococcus pneumoniae,Haemophilus influenzae, andStaphylococcus aureusat delivery among 854 women participating in a randomized controlled trial in Papua New Guinea. Serotyping was performed, and antibiotic susceptibility was evaluated by disk diffusion and Etest. Potential risk factors for carriage were examined. Nasopharyngeal carriage at delivery ofS. pneumoniae(SPAZ, 7.2% [30/418], versus SPCQ, 19.3% [84/436];P< 0.001) andH. influenzae(2.9% [12/418] versus 6.0% [26/436],P= 0.028), but notS. aureus, was significantly reduced among women who had received SPAZ-IPTp. The number of macrolide-resistant pneumococcal isolates was small but increased in the SPAZ group (13.3% [4/30], versus SPCQ, 2.2% [2/91];P= 0.033). The proportions of isolates with serotypes covered by the 13-valent pneumococcal conjugate vaccine were similar (SPAZ, 10.3% [3/29], versus SPCQ, 17.6% [16/91];P= 0.352). Although macrolide-resistant isolates were rare, they were more commonly detected in women who had received SPAZ-IPTp, despite the significant reduction of maternal carriage ofS. pneumoniaeandH. influenzaeobserved in this group. Future studies on SPAZ-IPTp should evaluate carriage and persistence of macrolide-resistantS. pneumoniaeand other pathogenic bacteria in both mothers and infants and assess the clinical significance of their circulation.

Download Full-text

Genetic Environment and Stability ofcfrin Methicillin-Resistant Staphylococcus aureus CM05

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.05420-11 ◽

2011 ◽

Vol 56 (1) ◽

pp. 332-340 ◽

Cited By ~ 44

Author(s):

Jeffrey B. Locke ◽

Shahad Rahawi ◽

Jacqueline LaMarre ◽

Alexander S. Mankin ◽

Karen Joy Shaw

Keyword(s):

Staphylococcus Aureus ◽

Recombination Event ◽

Sequence Similarity ◽

Ribosomal Subunit ◽

23S Rrna ◽

Broad Host Range ◽

Chromosomal Locus ◽

Methicillin Resistant ◽

Content Type ◽

Fitness Advantage

ABSTRACTThe Cfr methyltransferase confers resistance to many 50S ribosomal subunit-targeted antibiotics, including linezolid (LZD), via methylation of the 23S rRNA base A2503 in the peptidyl transferase center. Methicillin-resistantStaphylococcus aureusstrain CM05 is the first clinical isolate documented to carrycfr. Whilecfris typically plasmid borne, in CM05 it is located on the chromosome and is coexpressed withermBas part of themlroperon. Here we evaluated the chromosomal locus, association with mobile genetic elements, and stability of thecfrinsertion region in CM05. Thecfr-containingmlroperon is located within a 15.5-kb plasmid-like insertion into 23S rRNA allele 4. The region surrounding thecfrgene has a high degree of sequence similarity to the broad-host-range toxin/antitoxin multidrug resistance plasmid pSM19035, including a secondermBgene downstream of themlrlocus andistAS-istBS. Analysis of several individual CM05 colonies revealed two distinct populations for which LZD MICs were either 8 or 2 μg/ml. In the LZDscolonies (designated CM05Δ), a recombination event involving the twoermBgenes had occurred, resulting in the deletion ofcfrand the 3′ flanking region (cfr-istAS-istBS-ermB). The fitness advantage of CM05Δ over CM05 (though not likely due to thecfrdeletion itself) results in the predominance of CM05Δ in the absence of selective pressure. Minicircles resulting from theermBrecombination event and the novel association ofcfrwith the pSM19035 plasmid system support the potential for the continued dissemination ofcfr.

Download Full-text

Frequency of Spontaneous Resistance to Peptide Deformylase Inhibitor GSK1322322 in Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00484-15 ◽

2015 ◽

Vol 59 (8) ◽

pp. 4644-4652 ◽

Cited By ~ 5

Author(s):

Sharon Min ◽

Karen Ingraham ◽

Jianzhong Huang ◽

Lynn McCloskey ◽

Sarah Rilling ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Streptococcus Pneumoniae ◽

Haemophilus Influenzae ◽

Streptococcus Pyogenes ◽

Pathogenic Bacteria ◽

Peptide Deformylase ◽

Missense Mutations ◽

Loss Of Function ◽

Content Type

ABSTRACTThe continuous emergence of multidrug-resistant pathogenic bacteria is compromising the successful treatment of serious microbial infections. GSK1322322, a novel peptide deformylase (PDF) inhibitor, shows goodin vitroantibacterial activity and has demonstrated safety and efficacy in human proof-of-concept clinical studies.In vitrostudies were performed to determine the frequency of resistance (FoR) to this antimicrobial agent in major pathogens that cause respiratory tract and skin infections. Resistance to GSK1322322 occurred at high frequency through loss-of-function mutations in the formyl-methionyl transferase (FMT) protein inStaphylococcus aureus(4/4 strains) andStreptococcus pyogenes(4/4 strains) and via missense mutations inStreptococcus pneumoniae(6/21 strains), but the mutations were associated with severein vitroand/orin vivofitness costs. The overall FoR to GSK1322322 was very low inHaemophilus influenzae, with only one PDF mutant being identified in one of four strains. No target-based mutants were identified fromS. pyogenes, and only one or no PDF mutants were isolated in three of the fourS. aureusstrains studied. InS. pneumoniae, PDF mutants were isolated from only six of 21 strains tested; an additional 10 strains did not yield colonies on GSK1322322-containing plates. Most of the PDF mutants characterized from those three organisms (35/37 mutants) carried mutations in residues at or in close proximity to one of three highly conserved motifs that are part of the active site of the PDF protein, with 30 of the 35 mutations occurring at position V71 (using theS. pneumoniaenumbering system).

Download Full-text

Pseudomonas aeruginosa PA14 Enhances the Efficacy of Norfloxacin against Staphylococcus aureus Newman Biofilms

Journal of Bacteriology ◽

10.1128/jb.00159-20 ◽

2020 ◽

Vol 202 (18) ◽

Cited By ~ 1

Author(s):

Giulia Orazi ◽

Fabrice Jean-Pierre ◽

George A. O’Toole

Keyword(s):

Cystic Fibrosis ◽

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Antimicrobial Agents ◽

Respiratory Infections ◽

Multiple Infection ◽

Bacterial Biofilms ◽

Interspecies Interactions ◽

Chronic Infections ◽

Content Type

ABSTRACT The thick mucus within the airways of individuals with cystic fibrosis (CF) promotes frequent respiratory infections that are often polymicrobial. Pseudomonas aeruginosa and Staphylococcus aureus are two of the most prevalent pathogens that cause CF pulmonary infections, and both are among the most common etiologic agents of chronic wound infections. Furthermore, the ability of P. aeruginosa and S. aureus to form biofilms promotes the establishment of chronic infections that are often difficult to eradicate using antimicrobial agents. In this study, we found that multiple LasR-regulated exoproducts of P. aeruginosa, including 2-heptyl-4-hydroxyquinoline N-oxide (HQNO), siderophores, phenazines, and rhamnolipids, likely contribute to the ability of P. aeruginosa PA14 to shift S. aureus Newman norfloxacin susceptibility profiles. Here, we observe that exposure to P. aeruginosa exoproducts leads to an increase in intracellular norfloxacin accumulation by S. aureus. We previously showed that P. aeruginosa supernatant dissipates the S. aureus membrane potential, and furthermore, depletion of the S. aureus proton motive force recapitulates the effect of the P. aeruginosa PA14 supernatant on shifting norfloxacin sensitivity profiles of biofilm-grown S. aureus Newman. From these results, we hypothesize that exposure to P. aeruginosa PA14 exoproducts leads to increased uptake of the drug and/or an impaired ability of S. aureus Newman to efflux norfloxacin. Surprisingly, the effect observed here of P. aeruginosa PA14 exoproducts on S. aureus Newman susceptibility to norfloxacin seemed to be specific to these strains and this antibiotic. Our results illustrate that microbially derived products can alter the ability of antimicrobial agents to kill bacterial biofilms. IMPORTANCE Pseudomonas aeruginosa and Staphylococcus aureus are frequently coisolated from multiple infection sites, including the lungs of individuals with cystic fibrosis (CF) and nonhealing diabetic foot ulcers. Coinfection with P. aeruginosa and S. aureus has been shown to produce worse outcomes compared to infection with either organism alone. Furthermore, the ability of these pathogens to form biofilms enables them to cause persistent infection and withstand antimicrobial therapy. In this study, we found that P. aeruginosa-secreted products dramatically increase the ability of the antibiotic norfloxacin to kill S. aureus biofilms. Understanding how interspecies interactions alter the antibiotic susceptibility of bacterial biofilms may inform treatment decisions and inspire the development of new therapeutic strategies.

Download Full-text

1202. Subinhibitory Concentrations of Omadacycline Inhibit Staphylococcus aureus Hemolytic Activity in Vitro

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.1387 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S622-S623

Author(s):

Alisa W Serio ◽

S Ken Tanaka ◽

Kelly Wright ◽

Lynne Garrity-Ryan

Keyword(s):

Staphylococcus Aureus ◽

Protein Synthesis ◽

Virulence Factors ◽

Hemolytic Activity ◽

Protein Biosynthesis ◽

The United States ◽

Aureus Strain ◽

Protein Synthesis Inhibitors ◽

Subinhibitory Concentrations

Abstract Background In animal models of Staphylococcus aureus infection, α-hemolysin has been shown to be a key virulence factor. Treatment of S. aureus with subinhibitory levels of protein synthesis inhibitors can decrease α-hemolysin expression. Omadacycline, a novel aminomethylcycline antibiotic in the tetracycline class of bacterial protein biosynthesis inhibitors, is approved in the United States for treatment of community-acquired bacterial pneumonia (CABP) and acute bacterial skin and skin structure infections (ABSSSI) in adults. This study was performed to determine the durability of inhibition and effect of subinhibitory concentrations of omadacycline on S. aureus hemolytic activity. Methods All experiments used the methicillin-sensitive S. aureus strain Wood 46 (ATCC 10832), a laboratory strain known to secrete high levels of α-hemolysin. Minimum inhibitory concentrations (MICs) of omadacycline and comparator antibiotics (tetracycline, cephalothin, clindamycin, vancomycin, linezolid) were determined. Growth of S. aureus with all antibiotics was determined and the percentage of hemolysis assayed. “Washout” experiments were performed with omadacycline only. Results S. aureus cultures treated with 1/2 or 1/4 the MIC of omadacycline for 4 hours showed hemolysis units/108 CFU of 47% and 59% of vehicle-treated cultures, respectively (Fig. 1A, 1B). In washout experiments, treatment with as little as 1/4 the MIC of omadacycline for 1 hour decreased the hemolysis units/108 CFU by 60% for 4 hours following removal of the drug (Table 1). Figure 1 Table 1 Conclusion Omadacycline inhibited S. aureus hemolytic activity in vitro at subinhibitory concentrations and inhibition was maintained for ≥ 4 hours after removal of extracellular drug (Fig. 2). The suppression of virulence factors throughout the approved omadacycline dosing interval, in addition to the in vitro potency of omadacycline, may contribute to the efficacy of omadacycline for ABSSSI and CABP due to virulent S. aureus. This finding may apply to other organisms and other virulence factors that require new protein synthesis to establish disease. Figure 2 Disclosures Alisa W. Serio, PhD, Paratek Pharmaceuticals, Inc. (Employee, Shareholder) S. Ken Tanaka, PhD, Paratek Pharmaceuticals, Inc. (Employee, Shareholder) Kelly Wright, PharmD, Paratek Pharmaceuticals, Inc. (Employee, Shareholder) Lynne Garrity-Ryan, PhD, Paratek Pharmaceuticals, Inc. (Employee, Shareholder)

Download Full-text