Anti-Bacterial Agents ; pharmacology ; Child ; Humans ; Macrolides ; pharmacology ; Microbial Sensitivity Tests ; Mycoplasma pneumoniae ; drug effects

Anti-Bacterial Agents ; pharmacology ; Child ; Drug Resistance, Bacterial ; genetics ; Humans ; Macrolides ; pharmacology ; Pediatrics ; Streptococcus pyogenes ; drug effects

Catalyzed by a family of enzymes called glycosyltransferases (GTases), glycosylation reactions are essential for the bioactivities of macrolide antibiotics which have been widely applied. Additionally, glycosylation is also an important strategy of microbial to get macrolide antibiotic resistance. Studies on the structure, function and application areas of macrolide GTases will lay the stable groundwork for the combinatorial biology. This paper introduced in detail the biological functions of macrolide glycosylation, and then made an in-depth discussion on the families and discoveries of macrolide GTases. The resistance mechanism with macrolide glycosyltion and the correlative GTases MGT have been reviewed afterwards. According to the flexible substrate specificity of macrolide GTases, the combinatorial biological applications on them were also seriously summarized here. At the end, the authors made a developmental prospect of macrolide GTases based on the studies of the research group.
Anti-Bacterial Agents ; metabolism ; pharmacology ; Drug Resistance, Bacterial ; Glucosyltransferases ; classification ; metabolism ; Glycosylation ; Macrolides ; chemistry ; metabolism ; Streptomyces ; enzymology ; Substrate Specificity

Drug-resistance has become a challenging clinical problem. Ketolides, a new class of erythromycin derivatives, have shown promising effectiveness in killing drug-resistant bacteria. This article reviews recent development in synthesis of ketolides, with focus on the modification and synthesis of some important positions on erythromycin A cycles.
Animals ; Anti-Bacterial Agents ; chemical synthesis ; chemistry ; pharmacology ; Drug Resistance, Bacterial ; Erythromycin ; analogs & derivatives ; chemical synthesis ; pharmacology ; Humans ; Ketolides ; chemical synthesis ; chemistry ; pharmacology ; Macrolides ; chemical synthesis

To improve spinosyn-producing strain and enhance spinosyns yield, we studied the effects of glycin concentration and the operational time, temperature and lysozyme concentration on protoplast preparation of Saccharopolyspora spinosa SP06081. We also studied different regeneration media and osmotic stabilizing agents. In addition, we compared the change of morphology and spinosyns yield of the regenerated strains. The results showed that the Saccharopolyspora spinosa SP06081 protoplast yield was the highest under these conditions: the collected mycelium from SP06081 grown in Tryptic Soy Broth (TSB) medium with 0.2% glycin for 48 h was treated by 0.1 mg/mL lysozyme at 28 degrees C for 20 min, then plated on the R2YE medium with sucrose as osmotic stabilizer, the number of regeneration protoplast was up to 10(8)/mL. The protoplast-regenerated strains exhibited changes in morphology and antibiotic production, 29.3% protoplast-regenerated strains was characterized by loose mycelium and abundant broken branches as did their parent. Among them, 58.2% strains presented the trend to positive variation in spinosad yield, with the highest spinosad yield of up to 582.0 mg/L, 85.6% higher than that of their parent. There is significant correlation between the morphological differentiation and antibiotic yield of the protoplast-regenerated strains from spinosyn-producing strain.
Culture Media ; pharmacology ; Drug Combinations ; Glycine ; pharmacology ; Insecticides ; metabolism ; Macrolides ; metabolism ; Muramidase ; pharmacology ; Protoplasts ; cytology ; drug effects ; Regeneration ; Saccharopolyspora ; genetics ; metabolism ; physiology

The aim of this study was to investigate antimicrobial susceptibilities and macrolide resistance mechanisms of beta-hemolytic viridans group streptococci (VGS) in a tertiary Korean hospital. Minimum inhibitory concentrations (MICs) of seven antimicrobials were determined for 103 beta-hemolytic VGS isolated from various specimens. The macrolide resistance mechanisms of erythromycin-resistant isolates were studied by the double disk test and polymerase chain reaction (PCR). The overall resistance rates of beta-hemolytic VGS were found to be 47.5% to tetracycline, 3.9% to chloramphenicol, 9.7% to erythromycin, and 6.8% to clindamycin, whereas all isolates were susceptible to penicillin G, ceftriaxone, and vancomycin. Among ten erythromycin-resistant isolates, six isolates expressed a constitutive MLSB (cMLSB) phenotype, and each of the two isolates expressed the M phenotype, and the inducible MLSB (iMLSB) phenotype. The resistance rates to erythromycin and clindamycin of beta-hemolytic VGS seemed to be lower than those of non-beta-hemolytic VGS in our hospital, although cMLSB phenotype carrying erm(B) was dominant in beta-hemolytic VGS.
Ceftriaxone/pharmacology ; Chloramphenicol/pharmacology ; Clindamycin/pharmacology ; Cross Infection/*genetics ; *Drug Resistance, Bacterial ; Erythromycin/pharmacology ; Humans ; Immunoenzyme Techniques ; Korea ; Macrolides/*pharmacology ; Penicillin G/pharmacology ; Phenotype ; Polymerase Chain Reaction ; Tetracycline/pharmacology ; Vancomycin/pharmacology ; Viridans Streptococci/*genetics/*metabolism

BACKGROUNDMycoplasma pneumoniae is a common pathogen that caused community-acquired pneumonia (CAP). P1 protein served as major adhesion and immunodominant protein in Mycoplasma pneumoniae, but little about P1 gene was learned and the relationship between P1 genotype and macrolide resistance has yet to be explored.

METHODSThe DNA sequence of the entire P1 gene from 35 strains isolated from clinical specimens collected in Beijing, China, in 2010 was determined. The resulting sequences were checked for known macrolide resistance mutations, such as A2063G, A2064G, C2617G in domain V of 23S rRNA. Antibiotic susceptibility test was done to further identify macrolide resistant strains.

RESULTSThirty-four clinical strains were type 1, and were identical to type 1 reference strain MP129. Only one clinical strain, MpYYM22, was type 2, and proved to be variant 2c. One synonymous point mutation in the P1 type 1 gene from two isolates was identified relative to the MP129 P1 sequence at nucleotide position (nt) 552 (C>A), while another two isolates had missense mutations at nt 2504 (G>A). This point mutation caused an amino acid change from glycine to glutamic acid. An AGT tri-nucleotide variable-number tandem repeat (VNTR), coding for serine and repeating 6-11 times, up to 15-16 times, was found in the region between the RepMP4 and RepMP2/3 elements in the 35 isolates examined. All 35 clinical strains, including MpYYM22, demonstrated macrolide resistance with the range of minimum inhibitory concentration (MIC) of erythromycin from 64 to 256 µg/ml, having an A2063G transition in domain V of the 23S rRNA gene.

CONCLUSIONSP1 type 1 was the dominant type of Mycoplasma pneumoniae in Beijing in 2010, although variant 2c strains were present. More samples are needed to determine whether there is a relationship between the P1 genotype and macrolide resistance, as the 35 strains examined did not allow a conclusive result. However, the AGT tri-nucleotide VNTR may be a more informative locus for multi-locus VNTR analysis.

Anti-Bacterial Agents ; pharmacology ; DNA, Bacterial ; Drug Resistance, Bacterial ; Genotype ; Humans ; Macrolides ; pharmacology ; Microbial Sensitivity Tests ; Mycoplasma pneumoniae ; drug effects ; genetics ; metabolism

OBJECTIVEMacrolide susceptibility and drug resistance mechanisms of clinical non-tuberculous mycobacteria (NTM) isolates were preliminarily investigated for more accurate diagnosis and treatment of the infection in China.

METHODSFour macrolides, including clarithromycin (CLAR), azithromycin (AZM), roxithromycin (ROX), and erythromycin (ERY), were used to test the drug susceptibility of 310 clinical NTM isolates from six provinces of China with the broth microdilution method. Two resistance mechanisms, 23S rRNA and erm, were analyzed with nucleotide sequence analysis.

RESULTSVaried effectiveness of macrolides and species-specific resistance patterns were observed. Most Mycobacterium abscessus subsp. massiliense were susceptible and all M. fortuitum were highly resistant to macrolides. All the drugs, except for erythromycin, exhibited excellent activities against slow-growing mycobacteria, and drug resistance rates were below 22.2%. Only four highly resistant strains harbored 2,058/2,059 substitutions on rrl and none of other mutations were related to macrolide resistance. G2191A and T2221C on rrl were specific for the M. abscessus complex (MABC). Seven sites, G2140A, G2210C, C2217G, T2238C, T2322C, T2404C, and A2406G, were specifically carried by M. avium and M. intracellulare. Three sites, A2192G, T2358G, and A2636G, were observed only in M. fortuitum and one site G2152A was specific for M. gordonae. The genes erm(39) and erm(41) were detected in M. fortuitum and M. abscessus and inducible resistance was observed in relevant sequevar.

CONCLUSIONThe susceptibility profile of macrolides against NTM was demonstrated. The well-known macrolide resistance mechanisms, 23S rRNA and erm, failed to account for all resistant NTM isolates, and further studies are warranted to investigate macrolide resistance mechanisms in various NTM species.

Anti-Bacterial Agents ; pharmacology ; Bacterial Proteins ; genetics ; metabolism ; China ; Drug Resistance, Bacterial ; Gene Expression Regulation, Bacterial ; Humans ; Macrolides ; pharmacology ; Mycobacterium ; drug effects ; genetics ; Polymorphism, Genetic

AIM: To discover anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) microbial natural products or their derivatives. METHOD: Azalomycin F5a (1) was prepared through fermentation of Streptomyces hygroscopicus var. azalomyceticus, and its derivatives were synthesized through hydrocarbylation in hydrocarbyl alcoholic-AcOH (4 : 1) and subsequent demalonylation with 2 mol·L(-1) KOH in MeOH-H2O (7 : 3). Their activities against MRSA ATCC 33592 and three clinical MRSA isolates were evaluated by the agar diffusion and broth microdilution methods. RESULTS: Four demalonylazalomycin F5a derivatives 2 to 5 were synthesized. The anti-MRSA activity assay indicated that compounds 1 to 5 showed remarkable activity against MRSA, and their minimum inhibitory concentrations (MICs) were respectively 3.0-4.0, 0.5-1.0, 0.67-1.0, 0.67-0.83, and 0.5-0.83 μg·mL(-1). CONCLUSION Azalomycin F5a and the demalonylazalomycin F5a derivatives 2-5 showed remarkable anti-MRSA activity, and the anti-MRSA activities of 2 to 5 were higher than that of 1, while the anti-MRSA activities of 2 to 5 showed no obvious differences. It was also shown that the malonyl monoester group of azalomycin F5a was less important for its anti-MRSA activity.
Anti-Bacterial Agents ; chemistry ; pharmacology ; Humans ; Macrolides ; chemistry ; pharmacology ; Methicillin-Resistant Staphylococcus aureus ; drug effects ; Microbial Sensitivity Tests ; Molecular Structure ; Staphylococcal Infections ; microbiology ; Structure-Activity Relationship

OBJECTIVEMutations in 23S rRNA gene are known to be associated with macrolide resistance in Mycoplasma pneumoniae (M. pneumoniae). However, these mutations alone do not fully explain the high resistance rates in Asia. The aim of this study was to investigate other possible mutations involved in macrolide resistance in M. pneumoniae.

METHODSThe whole genomes of 10 clinical isolates of M. pneumoniae with macrolide resistance were sequenced by Illumina HiSeq2000 platform. The role of the macrolide-specific efflux transporter was assessed by efflux-pump inhibition assays with reserpine and carbonyl cyanide m-chlorophenyl-hydrazone (CCCP).

RESULTSA total of 56 single nucleotide polymorphisms (SNPs) were identified in 10 clinical isolates in comparison to the reference strains M129 and FH. Strikingly, 4 of 30 SNPs causing non-synonymous mutations were clustered in macrolide-specific efflux system gene macB encoding macrolide-specific efflux pump protein of the ATP-binding cassette transporter family. In assays of the minimal inhibitory concentrations (MIC) of macrolide antibiotics in the presence of the efflux pump inhibitors caused a significant decrease of MICs, even under detectable levels in some strains.

CONCLUSIONOur study suggests that macrolide efflux pump may contribute to macrolide resistance in M. pneumoniae in addition to the common point mutations in 23S rRNA gene.

Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Bacterial ; genetics ; Genome-Wide Association Study ; Macrolides ; pharmacology ; Microbial Sensitivity Tests ; Mutation ; Mycoplasma pneumoniae ; drug effects ; genetics