Macrolide-lincosamide-streptogramin Research Articles

The cervicovaginal microbiome and its resistome in a random selection of Afro-Caribbean women

The cervicovaginal microbiome consists of community state types (CSTs) I-V. Several studies have reported positive correlations between health issues such as bacterial vaginosis (BV), acquisition of sexually transmitted infections (STIs), preterm labour and CST IV. The cervicovaginal microbiome in Afro-Caribbean women has never been characterized. Hence, this study aimed to determine the composition, CST, microbial function and resistome of the cervicovaginal microbiome in a cohort of Afro-Caribbean women using targeted (16S rRNA V4) and whole genome shotgun metagenomics. CST IV predominated in this ethnic group, with Prevotella (13.91 %) being the most abundant genus followed by Gardnerella (12.14 %). The relative abundance for Lactobacillus was 9.37 %. The most abundant species for Prevotella and Lactobacillus were P. timonensis (5.00 %) and L. iners (7.00 %), respectively. Taxa with significant nucleotide similarity to the less virulent culture collection strain G. vaginalis 409–05 (8.14 %) were more abundant than G. vaginalis ATCC 14019 (4.00 %) in this group that was asymptomatic of BV. Functional profiling revealed a high abundance of biological processes (such as flagellum-dependent cell motility, cell adhesion and quorum sensing) associated with biofilm activity. In the resistome, 2,753 predicted antimicrobial resistance (AMR) genes consisting of 28 types (mostly tet and Emr; relative abundance 52.94 % and 16.18 %, respectively) that can potentially confer resistance to tetracyclines and the macrolide-lincosamide streptogramin B group were identified. Theoretically, these AMR genes can impact the effectiveness of antibiotics commonly used in the treatment of STIs and BV. This study is the first to provide insight into the cervicovaginal microbiome and its resistome in Afro-Caribbean women.

Potential Target Site for Inhibitors in MLSB Antibiotic Resistance.

Macrolide–lincosamide–streptogramin B antibiotic resistance occurs through the action of erythromycin ribosome methylation (Erm) family proteins, causing problems due to their prevalence and high minimal inhibitory concentration, and feasibilities have been sought to develop inhibitors. Erms exhibit high conservation next to the N-terminal end region (NTER) as in ErmS, 64SQNF67. Side chains of homologous S, Q and F in ErmC’ are surface-exposed, located closely together and exhibit intrinsic flexibility; these residues form a motif X. In S64 mutations, S64G, S64A and S64C exhibited 71%, 21% and 20% activity compared to the wild-type, respectively, conferring cell resistance. However, mutants harboring larger side chains did not confer resistance and retain the methylation activity in vitro. All mutants of Q65, Q65N, Q65E, Q65R, and Q65H lost their methyl group transferring activity in vivo and in vitro. At position F67, a size reduction of side-chain (F67A) or a positive charge (F67H) greatly reduced the activity to about 4% whereas F67L with a small size reduction caused a moderate loss, more than half of the activity. The increased size by F67Y and F67W reduced the activity by about 75%. In addition to stabilization of the cofactor, these amino acids could interact with substrate RNA near the methylatable adenine presumably to be catalytically well oriented with the SAM (S-adenosyl-L-methionine). These amino acids together with the NTER beside them could serve as unique potential inhibitor development sites. This region constitutes a divergent element due to the NTER which has variable length and distinct amino acids context in each Erm. The NTER or part of it plays critical roles in selective recognition of substrate RNA by Erms and this presumed target site might assume distinct local structure by induced conformational change with binding to substrate RNA and SAM, and contribute to the specific recognition of substrate RNA.

Investigation of the Prevalence of Antibiotic Resistance Genes According to the Wastewater Treatment Scale Using Metagenomic Analysis.

Although extensive efforts have been made to investigate the dynamics of the occurrence and abundance of antibiotic resistance genes (ARGs) in wastewater treatment plants (WWTPs), understanding the acquisition of antibiotic resistance based on the WWTP scale and the potential effects on WWTPs is of relatively less interest. In this study, metagenomic analysis was carried out to investigate whether the WWTP scale could be affected by the prevalence and persistence of ARGs and mobile genetic elements (MGEs). As a result, 152 ARG subtypes were identified in small-scale WWTP samples, while 234 ARG subtypes were identified in large-scale WWTP samples. Among the detectable ARGs, multidrug, MLS (macrolide–lincosamide–streptogramin), sulfonamide, and tetracycline resistance genes had the highest abundance, and large and small WWTPs had similar composition characteristics of ARGs. In MGE analysis, plasmids and integrons were 1.5–2.0-fold more abundant in large-scale WWTPs than in small-scale WWTPs. The profile of bacteria at the phylum level showed that Proteobacteria and Actinobacteria were the most dominant bacteria, representing approximately 70% across large- and small-scale WWTPs. Overall, the results of this study elucidate the different abundances and dissemination of ARGs between large- and small-scale WWTPs, which facilitates the development of next-generation engineered wastewater treatment systems.

Distribution of Macrolide-Lincosamide-Streptogramin B Antibiotics Resistance Genes in Clinical Isolates of Staphylococci.

Staphylococci are posing threat due to increasing trend of antimicrobial resistance particularly methicillin. Macrolide lincosamide streptogramin B (MLSB) family of antibiotics is commonly used to treat such infections. This study was aimed to determine the prevalence of inducible clindamycin resistance and observation of erm and msr genes among Staphylococci isolated from tertiary care hospital of Nepal during July 2017 to March 2018. Staphylococci from different clinical specimens were identified and antibiotic susceptibility profile was assessed following Kirby Bauer disc diffusion method. The double disc diffusion or D-zone test as outlined in CLSI document M100-S24 was performed to examine inducible clindamycin resistant isolates. Multiplex PCR was performed for detection of erm and msr gene in isolates using specific primers for ermA, ermB, ermC, msrA and msrB genes. Of the 60 Staphylococci isolates, 39 (65%) were S. aureus and 21 (35%) were coagulase negative Staphylococci (CNS) with 25 (64%) and 15 (71%) representing methicillin resistant S. aureus and CNS respectively. Constitutive and inducible MLSB phenotype was observed among 24 (40%) and 14 (23%) isolates respectively by D test. The most prevalent resistant gene was ermC (37%) followed by msrB (12%), ermB (10%) and msrA (10%). None of the isolates were found to possess ermA gene. The presence of constitutive and inducible MLSB as well as resistant genes among Staphylococci necessitates detection of such isolates to minimize treatment failure. The result from this study may help elucidate the predominant resistant characteristics in clinical Staphylococci isolated from tertiary care hospital of Nepal.

Inducible Clindamycin resistance and MRSA amongst Staphylococcus aureus isolates: A phenotypic detection

Now a days clinicians switch over to drug Clindamycin to treat infections. Clindamycin is belonging to lincosamide group. As frequent use of this Clindamycin develops resistance among patients and ultimately treatment failure. This present research is done to identify type of resistance like inducible or constitutive macrolide lincosamide – streptogramin B (iMLSB /cMLSB) resistance and MS (Macrolide lincosamide streptogramin) phenotypes among isolated from various samples received in Microbiology laboratory of tertiary care hospital of south Gujarat. Among various samples total 232 were isolated. And all these isolates were subjected to routine antibiotic sensitivity testing by kirbey bauer disc diffusion method. Methicillin resistance (MRSA) detected by using Cefoxitin disc. D test is performed as per Clinical and laboratory standards institute (CLSI) guidelines on all isolates. Total of 232 were isolated, among them 109 were Methicillin sensitive (MSSA) and 123 were Methicillin resistant (MRSA). Prevalence of iMLSB, cMLSB and MS phenotype were 59.34% ,15.44% and 13% in MRSA while 12.84%, 14.67% and 22.93% respectively in MSSA. This research helps to detect Clindamycin resistance among and role of D test before starting the treatment with Clindamycin. By these knowledge clinician can choose correct treatment and we can prevent a treatment failure.

Selection of antibiotic resistance genes on biodegradable and non-biodegradable microplastics

Growing evidence have demonstrated that microplastics in the marine ecosystem can provide novel substrates for biofilm formation, potentially facilitating the spread of antibiotic resistance. However, the occurrence of antibiotic resistance genes (ARGs) in the biofilm on microplastics has not been fully explored. This study used the metagenomic data of biodegradable and non-biodegradable microplastics staged at a coastal lagoon in the northern Gulf of Mexico to profile the ARGs and their bacterial hosts. The abundance and Shannon diversity of ARGs on biodegradable poly hydroxy alkanoate (PHA) and non-biodegradable polyethylene terephthalate (PET) have no significant differences. Nevertheless, the abundance of multidrug resistance genes on PET (3.05 copies per 16S rRNA) was statistically higher than that on PHA (2.05). Beta diversity showed that the overall pattern of resistome on PHA was significantly distinct with that on PET. Procrustes analysis suggested a good-fit correlation between ARG profiles and bacterial community composition. The host-tracking analysis identified that Pseudomonas was always the major host for glycopeptide and multidrug resistance genes in PET and PHA biofilms, whereas the primary host for macrolide-lincosamide-streptogramin (MLS) changed to Desulfovibrio on PET. This study provided the first metagenomic insights into the ARGs and their hosts on biodegradable and non-biodegradable microplastics, suggesting that both two types of plastics harbor ARGs with preferences.

The distribution of microbiomes and resistomes across farm environments in conventional and organic dairy herds in Pennsylvania

BackgroundAntimicrobial resistance is a serious concern. Although the widespread use of antimicrobials in livestock has exacerbated the emergence and dissemination of antimicrobial resistance genes (ARG) in farm environments, little is known about whether antimicrobial use affects distribution of ARG in livestock systems. This study compared the distribution of microbiomes and resistomes (collections of ARG) across different farm sectors in dairy herds that differed in their use of antimicrobials. Feces from heifers, non-lactating, and lactating cows, manure storage, and soil from three conventional (antimicrobials used to treat cows) and three organic (no antimicrobials used for at least four years) farms in Pennsylvania were sampled. Samples were extracted for genomic DNA, processed, sequenced on the Illumina NextSeq platform, and analyzed for microbial community and resistome profiles using established procedures.ResultsMicrobial communities and resistome profiles clustered by sample type across all farms. Overall, abundance and diversity of ARG in feces was significantly higher in conventional herds compared to organic herds. The ARG conferring resistance to betalactams, macrolide-lincosamide-streptogramin (MLS), and tetracyclines were significantly higher in fecal samples of dairy cows from conventional herds compared to organic herds. Regardless of farm type, all manure storage samples had greater diversity (albeit low abundance) of ARG conferring resistance to aminoglycosides, tetracyclines, MLS, multidrug resistance, and phenicol. All soil samples had lower abundance of ARG compared to feces, manure, and lagoon samples and were comprised of ARG conferring resistance to aminoglycosides, glycopeptides, and multi-drug resistance. The distribution of ARG is likely driven by the composition of microbiota in the respective sample types.ConclusionsAntimicrobial use on farms significantly influenced specific groups of ARG in feces but not in manure storage or soil samples.

Distribution patterns of antibiotic resistance genes and their bacterial hosts in pig farm wastewater treatment systems and soil fertilized with pig manure

Vast reservoirs of antibiotic resistance genes (ARG) are discharged into the environment via pig manure. We used metagenomic analysis to follow the distribution and shifts of ARGs and their bacterial hosts along wastewater treatment in three large pig farms. The predominating ARGs potentially encoded resistance to tetracycline (28.13%), aminoglycosides (23.64%), macrolide-lincosamide-streptogramin (MLS) (12.17%), sulfonamides (11.53%), multidrug (8.74%) and chloramphenicol (6.18%). The total relative ARG abundance increased along the treatment pathway prior to anaerobic digestion that had a similar degradative capacity for different ARGs and these ARGs were reduced by about 25% after digestion, but ARGs enriched erratically in manured soils. Distinctive ARG distribution patterns were found according to the three sample locations; feces, soil and wastewater and the differences were primarily due to the tetracycline ARGs (feces > wastewater > soil), sulfonamide ARGs (soil > wastewater > feces) and MLS ARGs (feces > wastewater > soil). Metagenomic assembly-based host analyses indicated the Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes were primary ARG carriers. The Streptococcaceae increased the abundance of multidrug, MLS and aminoglycoside ARGs in feces; Moraxellaceae were the primary contributors to the high abundance of multidrug ARGs in wastewater; the Comamonadaceae led to the higher abundance of bacA in wastewater and soil than feces. We found a high level of heterogeneity for both ARGs and ARG-hosts in the wastewater treatment system and in the agricultural soils for these pig farms.

The key environmental influencing factors for the change of sediment bacterial community and antibiotics resistance genes in a long-term polluted lake, China.

In order to investigate the key environmental influencing factors for the change of sediment bacterial community structure (BCS) and antibiotics resistance genes (ARGs) in a long-term Quinolone antibiotics (QNs) and heavy metals (HMs) polluted lake, 16S rRNA MiSeq High-throughput Sequencing and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis methods were applied. Baiyangdian lake was subdivided into three habitats: (1) Habitat 1: greatly influenced by municipal wastewater; (2) Habitat 2: mainly impacted by aquaculture sewage and domestic wastewater; and (3) Habitat 3: with the least human activities. Through One-way ANOVA analysis, the results showed that most of QNs and HMs showed significant difference among three habitats. Both the highest richness and diversity indices of bacterial community appeared in Habitat 3. The abundance of Multidrug, Phenicol, Aminoglycoside, Teracycline, and Quinolone ARGs exhibited the highest values in Habitat 1, while the abundance of Macrolide-Lincosamide-Streptogramin (MLS), Rifamycinm, and Sulfonamide ARGs appeared the highest values in Habitat 2. The result of redundancy analysis exhibited that 68.8% and 93.8% of the change in BCS and ARGs can be explained by environmental factors, respectively. Pb (explained 37.5% (p = 0.002)) and Fleroxacin (FLE) (explained 51.3% (p = 0.026)) were the most important factors for the variation of BCS and ARGs, respectively. Therefore, the effects of antibiotics and HMs on BCS and ARGs should be simultaneously paid more attention. Furthermore, the ARGs results by PICRUSt were similar to the results by metagenomic shotgun sequencing analysis, thus the PICRUSt analysis method can be used in the future research.

Metagenomic Analysis Reveals the Distribution of Antibiotic Resistance Genes in a Large-Scale Population of Healthy Individuals and Patients With Varied Diseases.

The human gut microbiome is a reservoir for antibiotic resistance gene (ARG). Therefore, characterizing resistome distribution and potential disease markers can help manage antibiotics at the clinical level. While much population-level research has highlighted the strong effect of donor geographic origin on ARG prevalence in the human gut, little is known regarding the effects of other properties, such as age, sex, and disease. Here we employed 2,037 fecal metagenomes from 12 countries. By quantifying the known resistance genes for 24 types of antibiotics in each community, we showed that tetracycline, aminoglycoside, beta-lactam, macrolide-lincosamide-streptogramin (MLS), and vancomycin resistance genes were the dominant ARG types in the human gut. We then compared the ARG profiles of 1427 healthy individuals from the 2,037 samples and observed significant differences across countries. This was consistent with expectations that regional antibiotic usage and exposure in medical and food production contexts affect distribution. Although no specific uniform pattern of ARG was observed, a significant increase in resistance potential among multiple disease groups implied that the disease condition may be another source of ARG variance. In particular, the co-occurrence pattern of some enriched bacterial species and ARGs that were obtained in type 2 diabetes (T2D) and liver cirrhosis patients implied that some disease-associated species may be potential hosts of enriched ARGs, which could be potential biomarkers for the prediction and intervention of such diseases. Overall, our study identifies factors associated with the human gut resistome, including substantial effects of region and heterogeneous effects of disease status, and highlights the value of ARG analysis in disease research and clinical applications.

In Vitro Activity Analysis of a New Polymyxin, SPR741, Tested in Combination with Antimicrobial Agents against a Challenge Set of Enterobacteriaceae, Including Molecularly Characterized Strains.

The activities of azithromycin, fusidic acid, vancomycin, doxycycline, and minocycline were evaluated alone and in combination with SPR741. A total of 202 Escherichia coli and 221 Klebsiella pneumoniae isolates were selected, and they included a genome-sequenced subset (n = 267), which was screened in silico for β-lactamase, macrolide-lincosamide-streptogramin (MLS), and tetracycline (tet) genes. Azithromycin (>16 mg/liter), fusidic acid (>64 mg/liter), vancomycin (>16 mg/liter), and SPR741 (>8 mg/liter) showed off-scale MICs when each was tested alone against all isolates. MIC50/90 results of 0.5/8 mg/liter, 4/>32 mg/liter, 16/>16 mg/liter, 2/32 mg/liter, and 0.25/4 mg/liter were obtained for azithromycin-SPR741, fusidic acid-SPR741, vancomycin-SPR741, doxycycline-SPR741 and minocycline-SPR741, respectively, against all isolates. Overall, azithromycin-SPR741 (MIC90, 2 to 4 mg/liter) and minocycline-SPR741 (MIC90, 0.5 to 2 mg/liter) showed the lowest MIC90 values against different subsets of E. coli isolates, except for azithromycin-SPR741 (MIC90, 16 mg/liter) against the AmpC and metallo-β-lactamase subsets. In general, minocycline-SPR741 (MIC90, 2 to 8 mg/liter) had the lowest MIC90 against K. pneumoniae isolates producing different groups of β-lactamases. The azithromycin-SPR741 MIC (MIC50/90, 2/32 mg/liter) was affected by MLS genes (MIC50/90 of 0.25/2 mg/liter against isolates without MLS genes), whereas doxycycline-SPR741 (MIC50/90, 0.5/2 versus 8/32 mg/liter) and minocycline-SPR741 (MIC50/90, 0.25/1 versus 1/8 mg/liter) MIC results were affected when tested against isolates carrying tet genes in general. However, minocycline-SPR741 inhibited 88.2 to 92.9% of tet-positive isolates regardless of the tet gene. The azithromycin-SPR741 MIC results (MIC50/90, 1/16 mg/liter) against isolates with enzymatic MLS mechanisms were lower than against those with ribosomal protection (MIC50/90, 16/>32 mg/liter). SPR741 increased the in vitro activity of tested codrugs at different levels and seemed to be dependent on the species and resistance mechanisms of the respective codrug.

Phenotypic Detection of Macrolide-Lincosamide-Streptogramin Resistance among Staphylococcus aureus and Staphylococcus epidermidis in Baghdad, Iraq

Introduction: Staphylococci emerged as the most frequent nosocomial and community-acquired pathogens. Macrolide-lincosamide-streptogramin (MLS) antibiotics resistance was increasing among Staphylococcus aureus and Staphylococcus epidermidis (S. epidermidis) isolates. Objective: In the present study, the aim was to detect the phenotypic resistance pattern of MLS (constitutive and inducible) among S. aureus and S. epidermidis isolated from Iraqi patients. Methods: A total of 120 staphylococcal isolates (60 S. aureus and 60 S. epidermidis) were isolated from urine, wound swab, blood, and sputum specimens, then specified by the VITEK 2 system. Whole isolates were investigated by the disk-diffusion method against many antibiotics, then they were checked for the MLS phenotype by the D-zone test. Results: Out of 60 S. aureus isolates and 60 S. epidermidis, the isolation rates from wound, urine, blood, and sputum were 66.6 and 50%, 16.7 and 26.7%, 11.7 and 18.3%, and 5% for each species, respectively. The higher frequency rates of resistance were showed against erythromycin, clindamycin, and streptomycin, for both S. aureus with 83.3, 53.3, and 83.3%, respectively, and S. epidermidis with 73.3, 45, and 76.7%, respectively. Constitutive MLS resistance phenotype (MLSc) was shown in 32 isolates (53.3%) of S. aureus and inducible MLS resistance phenotype (MLSi) was noted in 16 isolates (26.7%). Conclusion: The current study concluded that the D-zone test must be applied within the routine work of the antimicrobial susceptibility test for staphylococcal isolates, to exclude the false results of staphylococcal isolates sensitivity against clindamycin.

Genetic Characterization of Methicillin-Resistant Staphylococcus aureus Isolates from Human Bloodstream Infections: Detection of MLSB Resistance.

In this study we aimed to characterize antimicrobial resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from bloodstream infections as well as the associated genetic lineages of the isolates. Sixteen MRSA isolates were recovered from bacteremia samples from inpatients between 2016 and 2019. The antimicrobial susceptibility of these isolates was tested by the Kirby–Bauer disk diffusion method against 14 antimicrobial agents. To determine the macrolide–lincosamide–streptogramin B (MLSB) resistance phenotype of the isolates, erythromycin-resistant isolates were assessed by double-disk diffusion (D-test). The resistance and virulence genes were screened by polymerase chain reaction (PCR). All isolates were characterized by multilocus sequence typing (MLST), spa typing, staphylococcal chromosomal cassette mec (SCCmec) typing, and accessory gene regulator (agr) typing. Isolates showed resistance to cefoxitin, penicillin, ciprofloxacin, erythromycin, fusidic acid, clindamycin, and aminoglycosides, confirmed by the presence of the blaZ, ermA, ermC, mphC, msrA/B, aac(6’)-Ie-aph(2’’)-Ia, and ant(4’)-Ia genes. Three isolates were Panton–Valentine-leukocidin-positive. Most strains (n = 12) presented an inducible MLSB phenotype. The isolates were ascribed to eight spa-types (t747, t002, t020, t1084, t008, t10682, t18526, and t1370) and four MLSTs (ST22, ST5, ST105, and ST8). Overall, most (n = 12) MRSA isolates had a multidrug-resistance profile with inducible MLSB phenotypes and belonged to epidemic MRSA clones.

Phenotypic and Molecular Detection of Macrolide Lincosamide Streptogramin B Resistance in Clinical Isolates of Staphylococci

Phenotypic and Molecular Detection of Macrolide Lincosamide Streptogramin B Resistance in Clinical Isolates of Staphylococci

Prevalence, Genetic Diversity, and Temporary Shifts of Inducible Clindamycin Resistance Staphylococcus aureus Clones in Tehran, Iran: A Molecular-Epidemiological Analysis From 2013 to 2018.

The prevalence of Staphylococcus aureus as an aggressive pathogen resistant to multiple antibiotics causing nosocomial and community-acquired infections is increasing with limited therapeutic options. Macrolide-lincosamide streptogramin B (MLSB) family of antibiotics represents an important alternative therapy for staphylococcal infections. This study was conducted over a period of five years from August 2013 to July 2018 to investigate the prevalence and molecular epidemiology in Iran of inducible resistance in S. aureus. In the current study, 126 inducible methicillin-resistant S. aureus (MRSA) (n = 106) and methicillin-sensitive S. aureus (MSSA) (n = 20) isolates were characterized by in vitro susceptibility analysis, resistance and virulence encoding gene distribution, phenotypic and genotypic analysis of biofilm formation, prophage typing, S. aureus protein A locus (spa) typing, staphylocoagulase (SC) typing, staphylococcal cassette chromosome mec (SCCmec) typing, and multilocus sequence typing. Of the 126 isolates, 76 (60.3%) were classified as hospital onset, and 50 (39.7%) were classified as community onset (CO). Biofilm formation was observed in 97 strains (77%). A total of 14 sequence types (STs), 26 spa types, 7 coagulase types, 9 prophage types, 3 agr types (no agr IV), and 9 clonal complexes (CCs) were identified in this study. The prevalence of the inducible MLSB (iMLSB) S. aureus increased from 7.5% (25/335) to 21.7% (38/175) during the study period. The iMLSB MRSA isolates were distributed in nine CCs, whereas the MSSA isolates were less diverse, which mainly belonged to CC22 (7.95%) and CC30 (7.95%). High-level mupirocin-resistant strains belonged to ST85-SCCmec IV/t008 (n = 4), ST5-SCCmec IV/t002 (n = 4), ST239-SCCmec III/t631 (n = 2), and ST8-SCCmec IV/t064 (n = 2) clones, whereas low-level mupirocin-resistant strains belonged to ST15-SCCmec IV/t084 (n = 5), ST239-SCCmec III/t860 (n = 3), and ST22-SCCmec IV/t790 (n = 3) clones. All the fusidic acid–resistant iMLSB isolates were MRSA and belonged to ST15-SCCmec IV/t084 (n = 2), ST239-SCCmec III/t030 (n = 2), ST1-SCCmec V/t6811 (n = 1), ST80-SCCmec IV/t044 (n = 1), and ST59-SCCmec IV/t437 (n = 1). The CC22 that was predominant in 2013–2014 (36% of the isolates) had almost disappeared in 2017–2018, being replaced by the CC8, which represented 39.5% of the 2017–2018 isolates. This is the first description of temporal shifts of iMLSB S. aureus isolates in Iran that identifies predominant clones and treatment options for iMLSB S. aureus–related infections.

Metagenome sequencing to unveil the resistome in a deep subtropical lake on the Yunnan-Guizhou Plateau, China

Erhai Lake in the Yunnan-Guizhou Plateau, a typical subtropical deep lake, experienced long-time input of nutrients and pollutants, which provides beneficial conditions for evolution and spread of resistance genes. In this study, the profile of bacterial community, antibiotic and metal resistance genes in sediments of Erhai Lake were analyzed via high-thought sequencing of 16S rRNA and metagenomic DNA. Proteobacteria, Firmicutes, Nitrospirae, and Bacteroidetes were found to be the main composition of the bacterial community. Multidrug-, bacitracin-, macrolide-lincosamide-streptogramin (MLS)- and tetracycline resistance genes were the primary antibiotic resistance gene (ARG) types with high relative abundance, whereas Multi-metal-, and arsenic- resistance genes were the primary metal resistance gene (MRG) types. The effects of nitrogen and phosphorus on the abundance of ARGs and MRGs depended on the different types. Some specific ARG (fosmidomycin resistance genes) and MRG types (multi-metal resistance genes) also showed significant geographic distribution. Bacterial community was the main driver shaping the resistome. Nutrients also played an essential role in structuring the bacterial community and resistome in the sediments of Erhai Lake. This study sheds light on the distribution and fate of resistome under a high load of nitrogen and phosphorus in a deep lake.

Solithromycin Can Specifically Induce Macrolide-Lincosamide-Streptogramin B Resistance.

Objectives: Solithromycin is a fluoroketolide that is considered to be a noninducing antibiotic for macrolide-lincosamide-streptogramin B resistance mediated by erm genes. The exact activity of solithromycin to induce erm gene expression remains to be determined. Materials and Methods: The potential of solithromycin to induce erm(A), erm(C), and erm(B) gene expression was examined using a lacZ reporter assay, double-disk diffusion test, and determination of the minimal inhibitory concentration after incubation with subinhibitory concentration of different antibiotics. Results: Neither solithromycin nor the ketolides telithromycin and cethromycin induced erm(A) or erm(C) gene expression. However, solithromycin could significantly induce erm(B) gene expression at levels greater than that seen for cethromycin and clindamycin, but less than that for erythromycin, rokitamycin, and telithromycin. Conclusion: Solithromycin does not induce erm(A) and erm(C) gene expression, but does induce erm(B) gene expression, although to a weaker extent than that seen for macrolides.

Metagenomic analysis reveals the microbiome and resistome in migratory birds

BackgroundAntibiotic-resistant pathogens pose high risks to human and animal health worldwide. In recent years, the role of gut microbiota as a reservoir of antibiotic resistance genes (ARGs) in humans and animals has been increasingly investigated. However, the structure and function of the gut bacterial community, as well as the ARGs they carry in migratory birds remain unknown.ResultsHere, we collected samples from migratory bird species and their associated environments and characterized their gut microbiomes and resistomes using shotgun metagenomic sequencing. We found that migratory birds vary greatly in gut bacterial composition but are similar in their microbiome metabolism and function. Birds from the same environment tend to harbor similar bacterial communities. In total, 1030 different ARGs (202 resistance types) conferring resistance to tetracycline, aminoglycoside, β-lactam, sulphonamide, chloramphenicol, macrolide-lincosamide-streptogramin (MLS), and quinolone are identified. Procrustes analysis indicated that microbial community structure is not correlated with the resistome in migratory birds. Moreover, metagenomic assembly-based host tracking revealed that most of the ARG-carrying contigs originate from Proteobacteria. Co-occurrence patterns revealed by network analysis showed that emrD, emrY, ANT(6)-Ia, and tetO, the hubs of ARG type network, are indicators of other co-occurring ARG types. Compared with the microbiomes and resistomes in the environment, migratory birds harbor a lower phylogenetic diversity but have more antibiotic resistance proteins. Interestingly, we found that the mcr-1 resistance gene is widespread among different birds, accounting for 50% of the total samples. Meanwhile, a large number of novel β-lactamase genes are also reconstructed from bird metagenomic assemblies based on fARGene software.ConclusionsOur study provides a comprehensive overview of the diversity and abundance of ARGs in migratory birds and highlights the possible role of migratory birds as ARG disseminators into the environment.9vRT3BmK5LZQjoS1YmKYZoVideo abstract.

Minimum influent concentrations of oxytetracycline, streptomycin and spiramycin in selecting antibiotic resistance in biofilm type wastewater treatment systems

It has been demonstrated that antibiotic resistance could be induced and selected under high antibiotic concentrations in biological wastewater treatment systems. However, little is available regarding the minimum concentrations of antibiotics for selecting antibiotic resistance during wastewater treatment. Herein, the minimum influent concentrations of oxytetracycline, streptomycin, and spiramycin in selecting antibiotic resistance in biofilm type wastewater treatment systems were investigated by spiking respective antibiotic into wastewater with an antibiotic dose increasing from 0 to 0.1, 1, 5, 25, 50 mg/L stepwise over a period of 606 days. Significant increase (p < .01) in the total abundance of antibiotic resistance genes was observed for both streptomycin and oxytetracycline at a dose of 0.1 mg/L according to metagenomic sequencing, while the concentration levels leading to significant increases (p < .05) in resistant bacteria ratio were higher: 5 mg/L for streptomycin and 25 mg/L for oxytetracycline. Although resistome abundance increased with the increase of spiramycin dose, neither the corresponding Macrolide-Lincosamide-Streptogramin (MLS) resistance genes nor the resistant bacteria ratio showed perceptible increase. Partial canonical correspondence analysis showed that both bacterial community shift and mobile genetic elements alteration contributed to the enrichment of resistomes under the presence of streptomycin and oxytetracycline. Regarding spiramycin which is mainly targeting on Gram-positive bacteria, the dominance of the intrinsically resisting Gram-negative bacteria in the biofilm microbiota might be responsible for the vague change of MLS resistant determinants under the spiramycin stress. The results demonstrated that it is possible to prevent the development of antibiotic resistance during wastewater treatment by controlling the influent streptomycin and oxytetracyline concentrations below 0.1 mg/L. This work proposed an actionable approach for the management of antibiotic production wastewater.

In Vitro Study of Constitutive and Inducible Clindamycin Resistance in Staphylococcus Aureus with Reference to Methicillin Resistant Staphylococcus Aureus: Experience From Tertiary Care Hospital in Punjab

Backround: Serious infections due to methicillin resistant Staphylococcus aureus (MRSA) have become a major clinical challenge. Globally Macrolide-lincosamide streptogramin B family of antibiotics are commonly used to treat such infections as an alternative to vancomycin. The study was to conducted to find out the presence of inducible clindamycin resistance among Staphylococcus aureus and their association with methicillin resistance. Method: The study conducted over one year (Jan 2016 - Dec 2016) in microbiology department of Guru Gobind Singh Medical College, Faridkot. Two hundred fifteen S.aureus isolates were included in the study. Methicillin resistance was detected by cefoxitin (30μg) disc diffusion method and inducible clindamycin resistance by erythromycin and clindamycin disc approximation test (D-Test). Results: Of the 215 clinical isolates of S. aureus , 140 (65.11%) were MRSA. Erythromycin and clindamycin resistance was seen in 79.06%(170/215) and 49.30% ( 106/215) respectively. Resistance to erythromycin and clindamycin were higher in MRSA than MSSA (erythromycin resistance:100%v s 22.5% and Clindamycin resistance:70.1% vs 10.6%). Both iMLSB and cMLSBphenotypes are predominant in MRSA. Conclusion: Detection of MRSA in our study shows the need to improve health care practices and to formulate new infection control policies to control MRSA infections. Inducible and constitutive resistance is comparatively higher in our study in MRSA .So It is necessary to perform D-test for detection of inducible clindamycin resistance among MRSA in routine antibiotic sensitivity testing so that therapeutic failures can be avoided.