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The ribosome and protein synthesis are major targets within the cell for inhibition by antibiotics, such as the tetracyclines. The tetracycline family of antibiotics represent a large and diverse group of compounds, ranging from the naturally produced chlortetracycline, introduced into medical usage in the 1940s, to second and third generation semi-synthetic derivatives of tetracycline, such as doxycycline, minocycline and more recently the glycylcycline tigecycline. Here we describe the mode of interaction of tetracyclines with the ribosome and mechanism of action of this class of antibiotics to inhibit translation. Additionally, we provide an overview of the diverse mechanisms by which bacteria obtain resistance to tetracyclines, ranging from efflux, drug modification, target mutation and the employment of specialized ribosome protection proteins. [ABSTRACT FROM AUTHOR]

Background: Dissemination of antibiotic resistant clones is recognized as an important factor in the emergence and prevalence of resistance in pneumococcus. This study was undertaken to survey the antimicrobial susceptibility and serotypes distribution of pneumococci and to explore the circulating clones in hospitalized children in Suzhou, China. Methods: The pneumococci were isolated from the nasopharyngeal aspirates of children less than 5 years of age admitted to Soochow-University-Affiliated-Children's-Hospital with respiratory infections. The capsular serotypes were identified by multiplex polymerase chain reaction (PCR). Antimicrobial susceptibility was tested by E-test. The presence of ermB, mefA/E genes were detected by PCR and the genotypes were explored by Multilocus sequence typing (MLST). Results: From July 2012 to July 2013, a total of 175 pneumococcal isolates were collected and all strains were resistant to erythromycin and clindamycin, about 39.4% strains were non-susceptible to penicillin G. Overall, 174 (99.4%) isolates were resistant to ≥3 types of antibiotics. Serotypes 19F (28.1%), 6B (19.7%), 19A (18.0%), and 23F (17.4%) were the most common serotypes in all identified strains. The serotypes coverage of PCV7 and PCV13 were 71.9% and 89.9%, respectively. Four international antibiotic-resistant clones, including Taiwan19F-14 (n = 79), Spain23F-1(n = 25), Taiwan23F-15(n = 7) and Spain6B-2(n = 7), were identified. The Taiwan19F-14 clones have a higher non-susceptibility rate in β-lactams than other clones and non-clone isolates (p<0.001). In addition, 98.7% Taiwan19F-14 clones were positive of both ermB and mefA/E genes, compare to 33.3% in other clones and non-clone strains. Conclusions: The spread of international antibiotic-resistant clones, especially Taiwan19F-14 clones, played a predominant role in the dissemination of antimicrobial resistant isolates in Suzhou, China. Considering the high prevalence of PCV7 serotypes and serotype 19A, the introduction of PCV13 may be a promising preventive strategy to control the increasing trend of clonal spread in China. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the gene transfer potential of mef(A)-containing Tn 120.3 to macrolide-susceptible Streptococcus pyogenes belonging to different emm types. Using the filter mating technique, Tn 1207.3 was transferred by conjugation to 23 macrolide-susceptible recipients representing 11 emm types. PCR analysis confirmed the presence of the mef(A) gene and the com EC junction regions of the Tn 1207.3 insertion in resultant transconjugants. Significant variation was found in the transfer frequency of Tn 1207. 3 to different Strep. pyogenes strains, and this phenomenon may contribute to the differences in mef(A) frequency observed among clinical isolates. Significance and Impact of the Study The spread of antimicrobial resistance among pathogenic bacteria is an important problem, but the mechanisms of horizontal transfer between strains and species are often poorly understood. For instance, little is known on how macrolide resistance spreads between strains of the human pathogen Strep. pyogenes and why certain strains more commonly display resistance than others. Here, we show that Strep. pyogenes strains vary greatly in their ability to acquire a transposon encoding macrolide resistance by horizontal gene transfer in vitro. These data provide a novel insight into the transfer of antibiotic resistance between bacterial strains and offer an explanation for the differences in the frequency of resistance determinates and resistance seen among clinical isolates. [ABSTRACT FROM AUTHOR]

The occurrence and antibiotic susceptibility profile of Staphylococcus isolates of healthy farm animal origin in Nkonkobe Municipality as well as the prevalence of putative antibiotic resistance genes were investigated using phenotypic and molecular methods. A total of 120 Staphylococcus isolates were isolated from 150 animal samples and consisted of Staphylococcus haemolyticus (30 %) and Staphylococcus aureus (23.3 %) from pig, Staphylococcus capitis (15 %) from goat, S. haemolyticus (5 %) and Staphylococcus xylosus (15 %) from cattle, and other staphylococci (11.7 %) from dead chicken and pigs. Besides this, the presence of these isolates was observed from the animal dung, showing that the organisms are shed to the environment. About 23.3 % of these isolates were coagulase-positive and 76.7 % were coagulase-negative Staphylococcus. Between 75 and 100 % of the isolates were resistant to penicillin G, tetracycline, sulfamethoxazole, and nalidixic acid; about 38 % were methicillin-resistant staphylococci, including 12.6 % methicillin-resistant S. aureus from pigs. In total, 12 % of all isolates were vancomycin resistant. Also, 12 % of the isolates were erythromycin resistant, while 40.2 % were resistant to ceftazidime. Only the genes mecA and mphC could be confirmed, whereas the genes vanA, vanB, ermA, ermB, and ermC could not be detected. The high phenotypic antibiotic resistance and the presence of some associated resistance genes is a potential threat to public health and suggest the animals to be important reservoirs of antibiotic resistance determinants in the environment. [ABSTRACT FROM AUTHOR]

Three new spirobisnaphthalenes (1-3) were isolated from the mangrove-derived fungus Rhytidhysteron sp., together with five known derivatives (4-8). The structures of the compounds were established on the basis of extensive spectroscopic data, and the relative configurations of their stereogenic carbons were determined by a single-crystal X-ray crystallographic analysis. Compounds 3-5 displayed cytotoxicity against both cancer cell lines, MCF-7 and CaSki, while 2 was active only on CaSKi cells. [ABSTRACT FROM AUTHOR]

The marine Gram-negative bacteria Rhodopirellula baltica and Oceanicaulis alexandrii have, in contrast to Escherichia coli, membrane insertases with extended positively charged C-terminal regions similar to the YidC homologues in mitochondria and Gram-positive bacteria. We have found that chimeric forms of E. coli YidC fused to the C-terminal YidC regions from the marine bacteria mediate binding of YidC to ribosomes and therefore may have a functional role for targeting a nascent protein to the membrane. Here, we show in E. coli that an extended C-terminal region of YidC can compensate for a loss of SRP-receptor function in vivo. Furthermore, the enhanced affinity of the ribosome to the chimeric YidC allows the isolation of a ribosome nascent chain complex together with the C-terminally elongated YidC chimera. This complex was visualized at 8.6 Å by cryo-electron microscopy and shows a close contact of the ribosome and a YidC monomer. [ABSTRACT FROM AUTHOR]

The aim of the studies was to identify immunogenic proteins of Streptococcus agalactiae (group B streptococcus; GBS) isolates. Investigation of the immunoreactivity with human sera allowed us to determine major immunogenic proteins which might be potential candidates for the development of vaccine. For the study, we have selected 60 genetically different, well-characterized GBS clinical isolates. The proteins immunoreactivity with 24 human sera from patients with GBS infections, carriers, and control group without GBS was detected by SDS- PAGE and Western blotting. As a result, some major immunogenic proteins were identified, of which four proteins with molecular masses of about 45 to 50 kDa, which exhibited the highest immunoreactivity features, were analyzed by LC-MS/MS. The proteins were identified by comparative analysis of peptides masses using MASCOT and statistical analysis. The results showed known molecules such as enolase (47.4 kDa), aldehyde dehydrogenase (50.6 kDa), and ones not previously described such as trigger factor (47 kDa) and elongation factor Tu (44 kDa). The preliminary results indicated that some GBS proteins that elicit protective immunity hold promise not only as components in a vaccine as antigens but also as carriers or adjuvants in polysaccharide conjugate vaccines, but more studies are needed. [ABSTRACT FROM AUTHOR]

The sub-therapeutic use of tylosin in commercial swine operations can produce selective pressure for the development of antibiotic resistant bacteria. When swine manure from such operations is applied on drained agricultural fields, it can lead to transport and dissemination of resistant microorganisms through soils, into tile drainage lines, and ultimately into surface waters. The objective of this study was to investigate the occurrence and transport of tylosin-resistant enterococci from two different tile-drained agricultural fields receiving biennial swine-waste applications during different seasons. Resistance to tylosin in manure, soil, and tile water was investigated by a phenotype-based method and polymerase chain reaction. All enterococci in manure samples obtained from the spring application were resistant to tylosin, whereas 68 % of the total enterococci from the fall application were resistant to tylosin. Average concentrations of total and tylosin-resistant enterococci in soil samples over the two sampling periods were 9.8 × 10 3 and 7.5 × 10 3 cfu/g of soil, respectively. Total and tylosin-resistant enterococci concentrations in tile water collected from the two plots were significantly different ( P < 0.05) during the spring and fall experiments. In drainage water, the total enterococci peaked at 2.6 × 10 3 and 5.0 × 10 3 cfu/100 mL for the fall and spring experiments, respectively, while tylosin-resistant enterococci peaked at 1.4 × 10 3 and 1.2 × 10 3 cfu/100 mL for the fall and spring experiments, respectively. Total suspended solid concentrations in tile water were correlated with enterococci concentrations when base flow was present. Seven out of eight macrolide-resistance genes tested were detected ( ermA, ermB, ermC, ermF, ermT, ermX, and msrA, but not mefA). Five of these genes ( ermB, ermC, ermF, ermT, and msrA) were detected in at least 9 % of the samples. On average, most of the phenotypically resistant isolates (97 %) harbored msrA, while only 10 % contained ermT and 9 % contained ermC. Genes containing e rmF and ermB were detected in 78 % and 69 % of resistant isolates, respectively. Only 2 % of the total isolates ( n = 4) harbored all five genes. Of the isolates collected from manure, soil, and water samples, 12 % were confirmed as Enterococcus faecalis with 96 % of the confirmed E. faecalis isolates containing multiple resistance genes. The findings from this study are useful to provide baseline information on the export of total and tylosin-resistant enterococci during rainfall events from manured, tile-drained agricultural fields of the Upper Midwestern USA. [ABSTRACT FROM AUTHOR]

Background The World Health Organization reported in 2007 that inclusion of PCV7 in national immunization programs should be seen as a priority, also encouraging countries to conduct appropriate surveillances for monitoring the impact of vaccination. These analyses should be conducted in specific geographical areas and should be aimed to evolution of invasive pneumococcal disease (IPD), by age groups, clinical presentation, and vaccine serotypes (and non-vaccine serotypes to detect possible replacement). This study aimed to monitor the evolution of IPD incidence in children <15 years requiring hospitalization in the Island of Majorca. Methods A prospective clinical surveillance of all culture and/or PCR-confirmed IPD in children <15 years was performed in all hospitals in the Island of Majorca (approximately 900,000 inhabitants) from January 2008 to December 2010. Incidence rate (IR) was calculated as cases/100000 inhabitants using children population data. Results 66 IPDs were identified: 39 (59.1%) parapneumonic pneumococcal empyema (PPE), 16 (24.2%) bacteremic pneumonia (BP), 7 (10.6%) primary bacteremia, 3 (4.5%) meningitis, and 1 (1.5%) osteomyelitis. IRs in the three-year study period were: 64.22 for children 12- < 24 months, 37.21 for those 24-59 months, 22.62 for those <12 months, and 3.98 for children >59 months. By study year, IRs were 21.25 in 2008, 19.89 in 2009 and 9.80 in 2010. The reduction found in 2010 was significant and due to significant reductions in IRs of IPDs caused by serotypes included in PCV10 and PCV13. Overall, estimated serotype coverage by conjugate vaccines was 12.1% for PCV7, 37.9% for PCV10 and 65.2% for PCV13. Of the 66 hospitalized children with IPD, 20 had received at least one dose of PCV7 (13 cases with identified serotype). None of these 13 cases was caused by PCV7 serotypes, all were caused by PCV13 serotypes and only 53.8% by PCV10 serotypes. Conclusions The results of the present study evidence the importance of expanding the number of serotypes covered by PCV, and the added value of PCV13 with respect to PCV10 and PCV7, even in an area of low prevalence of 19A as the Island of Majorca. [ABSTRACT FROM AUTHOR]

High-speed counter-current chromatography (HSCCC) was applied for the first time for the preparative separation of spirobisnaphthalenes from a crude extract of the endophytic fungus Berkleasmium sp. Dzf12, associated with the medicinal plant Dioscorea zingiberensis. Six spirobisnaphthalenes were successfully separated by HSCCC with a two-phase solvent system composed of n-hexane-chloroform-methanol-water (1.5:3.0:2.5:2.0, v/v). About 18.0 mg of diepoxin κ (1), 245.7 mg of palmarumycin C13 (2), 42.4 mg of palmarumycin C16 (3), 42.2 mg of palmarumycin C15 (4), 32.6 mg of diepoxin δ (5), and 22.3 mg of diepoxin γ (6) with purities of 56.82, 71.39, 76.57, 75.86, 91.01 and 82.48%, respectively, as determined by high-performance liquid chromatography (HPLC), were obtained from 500 mg of the crude extract in a one-step elution within 7 h of separation procedure by HSCCC. The purified spirobisnaphthalenes were further structurally characterized by means of physicochemical and spectrometric analysis. [ABSTRACT FROM AUTHOR]

We investigated the genetic structure of 99 isolates of serotype 23F Streptococcus pneumoniae from children with acute respiratory infections collected over two periods from 1997 to 2006, and 2010. All isolates were susceptible to vancomycin and amoxicillin–clavulanic acid; 97 were resistant to erythromycin, 95 of which carried the ermB gene and two carried both mefA/E and ermB genes. Multidrug resistance to three or more classes of antibiotics was exhibited by 90 isolates. Sequence types ST342 and ST81 were the most frequent in 1997–2006 and 2010, respectively. All CC81 isolates were non-susceptible to β-lactam antibiotics and had higher minimum inhibitory concentration values for penicillin than other clone complexes and sequence types. The increased β-lactam antibiotic resistance may have resulted from the replacement of multidrug-resistant clones related to ST81. Long-term studies on S. pneumoniae serotype 23F, especially the ST81 clone, should be conducted to better understand the epidemiological picture of this pathogen in China. [ABSTRACT FROM AUTHOR]

Background: Antimicrobial resistance among pneumococci has greatly increased over the past two to three decades. Resistance to tetracycline (tet(M)), chloramphenicol (cat) and macrolides (erm(B) and/or mef(A/E)) is generally conferred by acquisition of specific genes that are associated with mobile genetic elements, including those of the Tn916 and Tn5252 families. The first tetracycline-, chloramphenicol- and macrolide-resistant pneumococci were detected between 1962 and 1970; however, until now the oldest pneumococcus shown to harbour Tn916 and/or Tn5252 was isolated in 1974. In this study the genomes of 38 pneumococci isolated prior to 1974 were probed for the presence of tet(M), cat, erm(B), mef(A/E) and int (integrase) to indicate the presence of Tn916/Tn5252-like elements. Results: Two Tn916-like, tet(M)-containing, elements were identified among pneumococci dated 1967 and 1968. The former element was highly similar to that of the PMEN1 multidrug-resistant, globally-distributed pneumococcal reference strain, which was isolated in 1984. The latter element was associated with a streptococcal phage. A third, novel genetic element, designated ICESpPN1, was identified in the genome of an isolate dated 1972. ICESpPN1 contained a region of similarity to Tn5252, a region of similarity to a pneumococcal pathogenicity island and novel lantibiotic synthesis/export-associated genes. Conclusions: These data confirm the existence of pneumococcal Tn916 elements in the first decade within which pneumococcal tetracycline resistance was described. Furthermore, the discovery of ICESpPN1 demonstrates the dynamic variability of pneumococcal genetic elements and is contrasted with the evidence for Tn916 stability. [ABSTRACT FROM AUTHOR]

The use of antimicrobial agents in swine production at subtherapeutic concentrations for the purpose of growth promotion remains controversial due to the potential impact on public health. Beginning at weaning (3 weeks), pigs received either nonmedicated feed or feed supplemented with subtherapeutic levels of either tylosin (11-44 ppm) or chlortetracycline (5.5 ppm). After only 3 weeks, pigs given feed supplemented with tylosin had significantly higher levels of tylosin-resistant anaerobes ( P < 0.0001) compared with the control group, increasing from 11.8% to 89.6%, a level which was stable for the duration of the study, even after a 2-week withdrawal prior to slaughter. Tylosin-fed pigs had a higher incidence of detection for erm(A), erm(F), and erm(G), as well as significantly ( P < 0.001) higher concentrations of erm(B) in their feces. The continuous administration of chlortetracycline-supplemented feed, however, had no significant effect on the population of chlortetracycline-resistant anaerobes in comparison with nontreated pigs ( P > 0.05). The resistance genes tet(O), tet(Q), and erm(B) were detected in all pigs at each sampling time, while tet(G), tet(L), and tet(M) were also frequently detected. Neither chlortetracycline nor tylosin increased the growth rate of pigs. [ABSTRACT FROM AUTHOR]

Background: Pneumococcal and Haemophilus influenzae type b (Hib) vaccines were introduced in our national immunisation program in April 2010. The aims of this retrospective, laboratory-based study were to determine the serotypes and antibiotic resistance of Streptococcus pneumoniae and H. influenzae isolates from middle ear fluid (MEF) collected before the introduction of immunization. Methods: S. pneumoniae (n = 128) and H. influenzae (n = 40) strains isolated from MEF of children with AOM between 1994 and 2011 were studied. MICs were determined by a microdilution assay. Serotyping of S. pneumoniae was done by Quellung method and PCR capsular typing was used for H. influenzae. Macrolide resistance genes were detected by PCR for erythromycin resistant S. pneumoniae (ERSP). DNA sequencing of ftsI gene was performed for ampicillin nonsusceptible H. influenzae. Results: The most common serotypes found among children with pneumococcal AOM were 19 F (20.3%), 6B (15.6%), and 19A (10.9%). The potential coverage rates by the PCV7, PCV10 and PCV13 of children aged < 5 years were 63.6%, 66.4% and 85.5%, respectively. Reduced susceptibility to oral penicillin was seen in 68.1%; resistance to erythromycin was 46.9%. We found erm(B) gene in 56.7% of the ERSP, mef(E) gene in 25%; 15% harbored both genes erm(B) + mef(E) and 3.3% had mutations of L4 ribosomal protein. Of the 40 H. influenzae isolates 97.5% were nontypeable. Nonsusceptibility to ampicillin occurred in 25%. Ampicillin resistance groups were: β-lactamase -positive ampicillin resistant (BLPAR) strains (10%), β-lactamase-negative ampicillin resistant (BLNAR) strains (12.5%) and β-lactamase-positive amoxicillin-clavulanate resistant (BLPACR) strains (2.5%). Among BLNAR and BLPACR most of the isolates (5/6) belonged to group II, defined by the Asn526Lys substitution. Conclusions: The levels of antibiotic resistance among S. pneumoniae and H. influenzae causing severe AOM in children are high in our settings. The existence of multidrug-resistant S. pneumoniae serotype 19A is of particular concern. The rate of BLNAR and BLPACR strains among H. influenzae isolates was 15%. [ABSTRACT FROM AUTHOR]

Fifty-three lactic acid bacteria ( LAB) strains from five species of bacteria were isolated and identified from yogurt and Chinese pickled vegetables. Susceptibility of all the isolates to five antibiotics (ampicillin, erythromycin, tetracycline, vancomycin, streptomycin) was tested with disc diffusion methods. All LAB were resistant to streptomycin. Thirty-seven strains were resistant to vancomycin, seven strains were resistant to tetracycline and erythromycin, and six strains were resistant to ampicillin. The corresponding genetic determinants were characterized by polymerase chain reaction. No antibiotic resistant gene was detected among all resistant strains. Biofilm-forming ability was monitored by a modified crystal violet staining method. Among the 53 strains, 32 strains showed different levels of biofilm-forming ability, while 21 strains did not form biofilms. The minimal inhibitory concentration of antibiotics ( MIC) and the biofilm inhibitory concentration ( BIC) were determined in the 32 strains which can form biofilms. There are significance correlations between biofilm formation and BIC/ MIC for all antibiotics ( P < 0.05) except vancomycin. Biofilms exhibited increased antimicrobial resistance compared with planktonic isolates, but the extent of enhanced antibiotic resistance in biofilms is different with different antibiotics. Practical Application Recently, there are increasing researches focusing on the safety of LAB, due to their antibiotic resistance. However, effects of antibiotic resistance in LAB were different in different application fields. So it is necessary to understand the mechanism of resistance all sidedly. In this study, we found those LAB isolates, which exhibiting antibiotics resistance in the susceptive tests, carried no transferable antibiotic resistance determinant, while there was a significant positive correlation between four antibiotics resistance and biofilm-forming ability. Data derived from this study can be used as a basis for assessing the safety of LAB applied in fermented food. [ABSTRACT FROM AUTHOR]

Little information is available on the distribution of antimicrobial resistance genes in anaerobes in Japan. To understand the background of antimicrobial resistance in anaerobes involved in intra-abdominal infections, we investigated the distribution of eight antimicrobial resistance genes ( cepA, cfiA, cfxA, ermF, ermB, mefA, tetQ, and nim) and a mutation in the gyrA gene in a total of 152 organisms ( Bacteroides spp., Prevotella spp., Fusobacterium spp., Porphyromonas spp., Bilophila wadsworthia, Desulfovibrio desulfuricans, Veillonella spp., gram-positive cocci, and non-spore-forming gram-positive bacilli) isolated between 2003 and 2004 in Japan. The cepA gene was distributed primarily in Bacteroides fragilis. Gene cfxA was detected in about 9 % of the Bacteroides isolates and 75 % of the Prevotella spp. isolates and did not appear to contribute to cephamycin resistance. Two strains of B. fragilis contained the metallo-β-lactamase gene cfiA, but they did not produce the protein product. Gene tetQ was detected in about 81, 44, and 63 % of B. fragilis isolates, other Bacteroides spp., and Prevotella spp. isolates, respectively. The ermF gene was detected in 25, 13, 56, 64, and 16 % of Bacteroides spp., Prevotella spp., Fusobacterium spp., B. wadsworthia, and anaerobic cocci, respectively. Gene mefA was found in only 10 % of the B. fragilis strains and 3 % of the non- B. fragilis strains. Genes nim and ermB were not detected in any isolate. Substitution at position 82 (Ser to Phe) in gyrA was detected in B. fragilis isolates that were less susceptible or resistant to moxifloxacin. This study is the first report on the distribution of resistance genes in anaerobes isolated from intra-abdominal infections in Japan. We expect that the results might help in understanding the resistance mechanisms of specific anaerobes. [ABSTRACT FROM AUTHOR]

Background. After the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in Alaska, the incidence of invasive pneumococcal disease (IPD) due to non-vaccine serotypes, particularly serotype 19A, increased. The aim of this study was to describe the molecular epidemiology of IPD due to serotype 19A in Alaska. Methods. IPD data were collected from 1986 to 2010 through population-based laboratory surveillance. Isolates were serotyped by the Quellung reaction and MICs determined by broth microdilution. Genotypes were assessed by multilocus sequence typing. Results. Among 3,294 cases of laboratory-confirmed IPD, 2,926 (89%) isolates were available for serotyping, of which 233 (8%) were serotype 19A. Across all ages, the proportion of IPD caused by serotype 19A increased from 3.5% (63/1823) pre-PCV7 (1986-2000) to 15.4% (170/1103) post-PCV7 (2001-2010) (p<0.001); among children B5 years of age, the proportion increased from 5.0% (39/776) to 33.0% (76/230) (p<0.001). The annual incidence rate of IPD due to serotype 19A (all ages) increased from 0.73 cases pre-PCV7 to 2.56 cases/ 100,000 persons post-PCV7 (p<0.001); rates among children <5 years of age increased from 4.84 cases to 14.1 cases/100,000 persons (p<0.001). Among all IPD isolates with reduced susceptibility to penicillin, 17.8% (32/180) were serotype 19A pre-PCV7 and 64% (121/189) were serotype 19A post-PCV7 (p<0.001). Eighteen different sequence types (STs) were identified; ST199 or single locus variants of ST199 (n=150) and ST172 (n=59) accounted for the majority of isolates. Multidrug-resistant isolates were clustered in ST199 and ST320. Conclusion. While PCV13 should significantly reduce the burden of disease due to 19A, these data highlight the need to continue surveillance for IPD to monitor the effects of vaccination on the expansion and emergence of non-PCV strains. [ABSTRACT FROM AUTHOR]

A total of 194 enterococcal isolates were recovered from 198 fecal samples of pigs, cattle, and sheep obtained in a Portuguese slaughterhouse. The enterococcal species most prevalent were Enterococcus faecium and E. hirae. High percentages of resistance were detected for tetracycline in pig isolates (95.7%), sheep isolates (76.7%), and cattle isolates (49%); erythromycin resistance was higher in pig isolates than in cattle or sheep isolates. Intermediate level of resistance was obtained to quinupristin/dalfopristin in all animal isolates (15.1-23.5%). High-level resistance to aminoglycosides was detected, HLR-S and -K was higher in pig isolates (44.3 and 32.9%, respectively) compared with cattle or sheep isolates, and modest percentages of HLR-G were obtained in pig and cattle isolates (7.1 and 3.9%, respectively). The aac(6`)- aph(2'), aph(3`)-IIIa, ant(6)-Ia, cat(A), erm(B), and tet(M) genes were demonstrated in most of the gentamycin-, kanamycin-, streptomycin-, chloramphenicol-, erythromycin- and tetracycline-resistant isolates, respectively. The association between the tet(M) gene and Tn 916/Tn 1545-like or Tn 5397-like transposons was detected in 30.8 and 11.2% of the isolates, respectively. Food animals could be a reservoir for antibiotic resistance genes, and slaughterhouse cross-contamination of animals carcasses may be a food safety risk. [ABSTRACT FROM AUTHOR]

The consequence of excessive use of macrolides is a high occurrence of mechanisms responsible for resistance to these drugs. Of 97 erythromycin-resistant bacterial strains gathered in the Wrocław area in Poland, 60% exhibited very high resistance, and those with the inducible MLS (macrolide-lincosamide-streptogramin B) resistance phenotype predominated. Direct genetic investigation revealed that the erm genes coding for ribosomal methylases are the most frequently occurring erythromycin resistance-determining genes. No genetic resistance determinant was detected in 13% of the erythromycin-resistant strains. The efflux mechanism occurs in strains isolated from the nasopharyngeal cavity twice as often as in those isolated from other material, where the mechanism connected with target site modification predominates. Measurements of radiolabelled antibiotic accumulation inside bacterial cells revealed that in highly resistant strains (MIC > 1024 μg/ml), an important factor responsible for the resistance is the permeability barrier at the cell wall level. This would be a hitherto unknown mechanism of resistance to erythromycin in Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria (LAB) resistant to erythromycin were isolated from different food samples on selective media. The isolates were identified as Enterococcus durans, Enterococcus faecium, Enterococcus lactis, Enterococcus casseliflavus, Lactobacillus salivarius, Lactobacillus reuteri, Lactobacillus plantarum, Lactobacillus fermentum, Pediococcus pentosaceus and Leuconostoc mesenteroides. Of the total 60 isolates, 88 % harbored the ermB gene. The efflux gene msrA was identified in E. faecium, E. durans, E. lactis, E. casseliflavus, P. pentosaceus and L. fermentum. Further analysis of the msrA gene by sequencing suggested its homology to msrC. Resistance to tetracycline due to the genes tetM, tetW, tetO, tetK and tetL, alone or in combination, were identified in Lactobacillus species. The tetracycline efflux genes tetK and tetL occurred in P. pentosaceus and Enterococcus species. Since it appeared that LAB had acquired these genes, fermented foods may be a source of antibiotic resistance. [ABSTRACT FROM AUTHOR]

Aims To study the antimicrobial resistance of coagulase-negative staphylococci ( Co NS) in animals. Methods and Results In the present study, a total of 87 Co NS recovered from food animals were characterized by antimicrobial susceptibility testing, resistance gene identification and conjugation. Of the seven species studied, Staphylococcus lentus, Staphylococcus sciuri, Staphylococcus xylosus and Staphylococcus haemolyticus accounted for over 96% of the isolates. In addition to β-lactam resistance (100%), high percentages of Co NS were resistant to tetracycline (67·8%), erythromycin (36·7%), clindamycin (27·5%) and quinopristin/dalfopristin (14·9%). Importantly, 47 (54%) isolates were resistant to at least three antimicrobial classes, including six Co NS resistant to six antimicrobial classes. The common genes for the above-mentioned resistance phenotypes were mec(A), tet(M), erm(A) and vga(A) LC, which were identified from 68·7%, 61%, 56·2% and 69·2% of the isolates, respectively. tet(M) was conjugatively transferable from 10 tetracycline-resistant Co NS to a Enterococcus strain, underlining the potential of antimicrobial resistance transfer from Staphylococcus to the commensal bacteria in human. Conclusions Multidrug resistance and resistance to non-β-lactam antimicrobials are common in Co NS in animals. Significance and Impact of the Study The data improve our understanding on the extent to which Co NS contribute to the dissemination of antimicrobial resistance in the food production environment. [ABSTRACT FROM AUTHOR]

Lignin peroxidase from the culture filtrate of Lenzitus betulina MTCC-1183 has been purified to homogeneity using concentration by ultrafiltration and anion exchange chromatography on DEAE cellulose. The molecular weight of the purified lignin peroxidase using SDS-PAGE analysis was 43 kDa. Specific activity of the enzyme was 29.58 IU/mg. The K values for veratryl alcohol and HO for the purified enzyme were 54 and 81 μM, respectively. The k value of the purified enzyme was 2.3 s using 3,4-dimethoxybenzyl alcohol as the substrate. The optimal conditions for the lignin peroxidase assay were detected at pH 2.4 and 22°C. Thermal stability of the purified enzyme has also been studied and its activation energy for deactivation was 287 kJ/mol. The purified lignin peroxidase depolymerised humic acid in presence of HO. Depolymerisation of coal by the L. betulina MTCC-1183 has been demonstrated using humic acid as a model of coal. [ABSTRACT FROM AUTHOR]

One hundred and forty-eight colonizing isolates from adult Romanian women were conventionally serotyped and screened for antibiotic resistance. Capsular type assignment by multiplex polymerase chain reaction (PCR) was performed for nonserotypeable isolates. Tetracycline and macrolide resistance genes ( tetM, tetO, tetL, ermA, ermB, and mefA) including tetM gene association with conjugative elements of the Tn 916 family were searched. Molecular typing included PCR screening for major surface protein antigen genes ( bac, bca, alp1, alp2/3, alp4, and rib), mobile genetic elements (GBSi1 and IS 1548), and rapid detection of hypervirulent clone ST-17. Genetic diversity was assessed by pulsed field gel electrophoresis (PFGE) analysis of SmaI macrorestriction patterns. Among the colonizing isolates studied, serotypes V and III predominated and high rates of tetracycline and macrolide resistance were observed. The tetM gene occurred in 140 tetracycline-resistant isolates and was associated with the int-Tn 916 gene in 94 of them. Most of the isolates displayed a constitutive MLS phenotype (38/46 isolates) and harbored the ermB gene. rib, alp2/3, and alp1 were the most common surface protein genes detected. Either IS 1548 or GBSi1 intron were detected in almost half of the isolates and nine serotype III isolates belonged to clone ST-17. PFGE analysis of SmaI macrorestriction patterns, obtained from 118 isolates, revealed an apparent genetic diversity. [ABSTRACT FROM AUTHOR]

Objectives Azithromycin is used widely for community-acquired infections. The timely administration of azithromycin in adequate doses minimizes treatment failure. Gastric bypass, a procedure that circumvents the upper gut, may compromise azithromycin plasma levels. We hypothesized that azithromycin concentrations would be reduced following gastric bypass. Methods A single-dose pharmacokinetic study in 14 female post-gastric bypass patients and 14 sex- and body mass index (BMI)-matched controls (mean age 44 years and BMI 36.4 kg/m2) was performed. Subjects were administered two 250 mg azithromycin tablets at time 0 and plasma azithromycin levels were sampled at 0.5, 1, 1.5, 2, 3, 5, 7 and 24 h. The AUC of the plasma azithromycin concentrations from time 0 to 24 h (AUC0–24) was the primary outcome. Results Azithromycin concentrations were lower in gastric bypass patients compared with controls throughout the entire duration of sampling. Compared with controls, the AUC0–24 was reduced in gastric bypass subjects by 32% [1.41 (SD 0.51) versus 2.07 (0.75) mg · h/L; P = 0.008], and dose-normalized AUC0–24 was reduced by 33% [0.27 (0.12) versus 0.40 (0.13) kg · h/L; P = 0.009]. Peak azithromycin concentrations were 0.260 (0.115) in bypass subjects versus 0.363 (0.200) mg/L in controls (P = 0.08), and were reached at 2.14 (0.99) h in gastric bypass subjects and 2.36 (1.17) h in controls (P = 0.75). Conclusions Azithromycin AUC was reduced by one-third in gastric bypass subjects compared with controls. The potential for early treatment failure exists, and dose modification and/or closer clinical monitoring of gastric bypass patients receiving azithromycin should be considered. [ABSTRACT FROM PUBLISHER]

The purpose of this investigation was to analyse Streptococcus agalactiae (group B Streptococcus, GBS) isolates collected in Italy from vaginal and urine samples in respect to their clonality, distribution of virulence factors and antimicrobial resistance determinants. Three hundred and eighty-eight GBS were recovered from clinical samples. They were analysed for antibiotic resistance profiling. Erythromycin-resistant strains were further characterised by multilocus sequence typing (MLST), serotyping and the detection of alp genes of the alpha-like protein (Alp) family. GBS isolates represented 40 different sequence types (STs), grouped in five clonal complexes (CCs) and belonged to seven serotypes. Most serotype V strains (81%) possessed alp2-3; serotype Ia carried mainly epsilon, while the serotype III mainly rib. All isolates were susceptible to penicillin, whereas resistance to erythromycin was detected in 15% of isolates. Most erythromycin-resistant GBS strains were of serotype V (56.8%) and belonged to the CC-1 group (50%). Macrolide resistance phenotypes were the cMLS (46.5%) and the M phenotypes (46.5%) due to the presence of ermB and mefA/E genes, respectively. These results provide data which establish a baseline for monitoring erythromycin resistance in this region and also provide an insight into the correlation among clonal types, serotypes, surface protein and resistance genes. The increased prevalence of strains that displayed the M phenotype strengthens the importance of the epidemiological surveillance of macrolide resistance in GBS, which may also represent an important reservoir of resistance genes for other species. [ABSTRACT FROM AUTHOR]

The asymptomatic oropharyngeal colonization rate by Streptococcus pyogenes was 10.7% in children (901 among 8,405 children 0-16 years old) and 3.3% in adults (37 among 1,126 households of children) in the Lisbon area during 2000-2006. Macrolide-resistant S. pyogenes from children ( n = 149) was variable with time: 9.8-10.7% in 2000-2002, 28.1% in 2003, 19.6-2.7% in 2004-2005 and 14.6% in 2006. Eight lineages (97.3% of isolates) were identified based on at least 80% similarity of PFGE patterns, T types, emm types and multilocus sequence types (ST). The elevated frequency of macrolide resistance was associated with M phenotype lineages I ( emm12/ST36) and V ( emm4, emm75/ST39 and a novel emmstMrp6 type) and with one cMLS lineage IV ( emm28/ST52) known to be associated with upper respiratory tract and invasive infections. Significant associations ( p < 0.05) between emm type/virulence genotype were found, such as emm1/ speA ssa, emm4/ ssa prtF1, emm12/ speA ssa. The high prevalence (>20%) of speC, prtF1 or ssa was probably caused either by clonal dissemination ( speC), or to horizontal gene transfer events ( prtF1 and ssa). This report contributes to a better understanding of the molecular epidemiology and evolution of macrolide-resistant S. pyogenes causing symptom-free oropharyngeal colonization. These colonizing strains carry macrolide resistance and virulence genes capable of being transferred to other bacterial species sharing the same niche. [ABSTRACT FROM AUTHOR]

The occurrence of staphylococci and enterococci expressing increased resistance to erythromycin (ERY) and, in particular, to macrolide-lincosamide-streptogramin B (MLSB) antibiotics was investigated in dairy cattle, pigs and turkeys. Three hundred rectal (cloacal) swabs of each animal species were examined. A total of 120 and 71 staphylococci and enterococci, respectively, with increased resistance to ERY were identified. These were most frequent in turkeys (42.3% of positive animals), followed by pigs and dairy cattle (6.7% and 6.0% of positive animals, respectively). Similarly, MLSB-resistant isolates colonized predominantly turkeys (29.7% of animals), while their occurrence in pigs and dairy cattle was only sporadic (0.8% of animals). At least one of the erm genes encoding for MLSB resistance was found in 56.7% and 69.0% of staphylococci and enterococci, respectively. The erm(C) gene prevailed in staphylococci while the erm(B) gene was predominant in enterococci. Macrolide efflux genes msr(A) and msr(C) were also frequent in staphylococci and enterococci, respectively. Macrolide inactivation gene mph(C) occurred mainly in staphylococci. In staphylococci, methicillin resistance was rarely detected (7.5% of isolates), but resistance to telithromycin (ketolides) was frequent in both staphylococci and enterococci (89.2% and 47.9% of isolates, respectively). This study showed that turkeys represent an important source of ERY (MLSB)-resistant cocci. In addition, resistance to ketolides was also frequent. [ABSTRACT FROM AUTHOR]

Group B Streptococcus (GBS) causes severe infections in infants and in immunocompromised adults. GBS pathogenicity varies between and within serotypes, with considerable variation in genetic content between strains. For this reason, it is important to be able to carry out immediate and comprehensive diagnostics of these infections. Seven genes important for screening of GBS infection were detected: cfb gene encoding the CAMP factor presented in every GBS; the cps operon genes such as cps1aH, cps1a/ 2/ 3IJ, and cps5O specific for capsular polysaccharide types Ia, III, and V, respectively; macrolide resistance genes ermB and mefA/E; and the gbs2018 S10 region specific for ST17 hypervirulent clone. Standardization of multiplex PCR with the use of seven primer pairs was performed on 81 bacterial strains representing different GBS isolates ( n = 75) and other Gram-positive cocci ( n = 10). Multiplex PCR can be used as an effective screening method to detect different sequences important for the screening of GBS infection. [ABSTRACT FROM AUTHOR]

In this study, three bacterial communities were obtained from 12 Leonardite samples with the aim of identifying a clean, effective, and economic technique for the dissolution of Leonardite, a type of low-grade coal, in the production of humic acid (HA). The biodegradation ability and characteristics of the degraded products of the most effective bacterial community (MCSL-2), which degraded 50% of the Leonardite within 21 days, were further investigated. Analyses of elemental composition, C NMR, and Fourier transform infrared revealed that the contents of C, O, and aliphatic carbon were similar in biodegraded humic acid (bHA) and chemically (alkali) extracted humic acid (cHA). However, the N and carboxyl carbon contents of bHA was higher than that of cHA. Furthermore, a positive correlation was identified between the degradation efficiency and the increasing pH of the culture medium, while increases of manganese peroxidase and esterase activities were also observed. These data demonstrated that both alkali production and enzyme reactions were involved in Leonardite solubilization by MCSL-2, although the former mechanism predominated. No fungus was observed by microscopy. Only four bacterial phylotypes were recognized, and Bacillus licheniformis-related bacteria were identified as the main group in MCSL-2 by analysis of amplified 16S rRNA genes, thus demonstrating that Leonardite degradation ability has a limited distribution in bacteria. Hormone-like bioactivities of bHA were also detected. In this study, a bacterial community capable of Leonardite degradation was identified and the products characterized. These data implicate the use of such bacteria for the exploitation of Leonardite as a biofertilizer. [ABSTRACT FROM AUTHOR]

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Background: We sought to characterize the temporal trends in nasopharyngeal carriage of macrolide-resistant pneumococci during a period with increased heptavalent pneumococcal conjugate vaccine (PCV7) coverage in Central Greece.Methods: Streptococcus pneumoniae isolates were recovered from 2649 nasopharyngeal samples obtained from day-care center attendees in Central Greece during 2005-2009. A phenotypic and genotypic analysis of the isolates was performed, including the identification of macrolide resistance genes mef(A), subclasses mef(A) and mef(E),as well as erm(B).Results: Of the 1105 typeable S. pneumoniae isolates, 265 (24%) were macrolide-resistant; 22% in 2005, 33.3% in2006, 23.7% in 2007, and 20.5% in 2009 (P=0.398). Among these macrolide-resistant pneumococci, 28.5% possessed erm(B), 24.3% erm(B)+mef(E), 41.8% mef(E), and 5.3% mef(A). A mef gene as the sole resistance determinant was carried by 31% of macrolide-resistant isolates belonging to PCV7 serotypes and 75.8% of the non-PCV7 serotypes.Across the 4 annual surveillances, pneumococci carrying mef(A) gradually disappeared, whereas serotype 19F isolates carrying both erm(B) and mef(E) persisted without significant yearly fluctuations. Among isolates belonging to non-PCV7 serotypes, macrolide-resistance was observed in those of serotypes 6A, 19A, 10A, 15A, 15B/C, 35F, 35A,and 24F. In 2009, ie 5 years after the introduction of PCV7 in our country, 59% of macrolide-resistant pneumococci belonged to non-PCV7 serotypes.Conclusions: Across the study period, the annual frequency of macrolide-resistant isolates did not change significantly, but in 2009 a marked shift to non-PCV7 serotypes occurred. Overall, more than half of the macrolide-resistant isolates possessed erm(B) either alone or in combination with mef(E). erm(B) dominated among isolates belonging to PCV7 serotypes, but not among those of non-PCV7 serotypes. [ABSTRACT FROM AUTHOR]

The addition of antibiotics to livestock feed has contributed to the selection of antibiotic-resistant bacteria in concentrated animal feeding operations and agricultural ecosystems. The objective of this study was to assess the occurrence of resistance to chlortetracycline and tylosin among bacterial populations at the Swine Complex of McGill University (Province of Quebec, Canada) in the absence of antibiotic administration to pigs for 2.5 years prior to the beginning of this study. Feces from ten pigs born from the same sow and provided feed without antibiotic were sampled during suckling ( n = 6 for enumerations, n = 10 for PCR), weanling ( n = 10 both for PCR and enumerations), growing ( n = 10 both for PCR and enumerations), and finishing ( n = 10 both for PCR and enumerations). The percentage of chlortetracycline-resistant anaerobic bacterial populations (Tet) was higher than that of tylosin-resistant anaerobic bacterial populations (Tyl) at weanling, growing, and finishing. Prior to the transportation of animals to the slaughterhouse, resistant populations varied between 6.5 and 9.4 Log colony-forming units g humid feces. In all pigs, tet(L), tet(O), and erm(B) were detected at suckling and weanling, whereas only tet(O) was detected at growing and finishing. The abundance of tet(O) was similar between males and females at weanling and growing and reached 5.1 × 10 and 5.6 × 10 copies of tet(O)/ng of total DNA in males and females, respectively, at finishing. Results showed high abundances and proportions of Tet and Tyl anaerobic bacterial populations, as well as the occurrence of tet and erm resistance genes within these populations despite the absence of antibiotic administration to pigs at this swine production facility since January 2007, i.e., 2.5 years prior to the beginning of this study. This work showed that the occurrence of bacterial resistance to chlortetracycline and tylosin is high at the Swine Complex of McGill University. [ABSTRACT FROM AUTHOR]

The article focuses on a study which determines macrolide resistance genotypes in clinical isolates of Streptococcus pneumoniae in Lebanon. It reports that several Streptococcus pneumoniae were tested in the medical centers for antimicrobial susceptibility and underwent molecular characterization. It concludes that S. pneumoniae is through target site modification and is also mediated through efflux pumps, invasive and most pervalent.

Background: Streptococcus pneumoniae is the main pathogen that causes respiratory infections in children younger than five years. The increasing incidence of macrolide- and tetracycline-resistant pneumococci among children has been a serious problem in China for many years. The molecular characteristics of erythromycin-resistant pneumococcal isolates that were collected from pediatric patients younger than five years in Beijing in 2010 were analyzed in this study. Results: A total of 140 pneumococcal isolates were collected. The resistance rates of all isolates to erythromycin and tetracycline were 96.4% and 79.3%, respectively. Of the 135 erythromycin-resistant pneumococci, 91.1% were non-susceptible to tetracycline. In addition, 30.4% of the erythromycin-resistant isolates expressed both the ermB and mef genes, whereas 69.6% expressed the ermB gene but not the mef gene. Up to 98.5% of the resistant isolates exhibited the cMLSB phenotype, and Tn6002 was the most common transposon present in approximately 56.3% of the resistant isolates, followed by Tn2010, with a proportion of 28.9%. The dominant sequence types (STs) in all erythromycin-resistant S. pneumoniae were ST271 (11.9%), ST81 (8.9%), ST876 (8.9%), and ST320 (6.7%), whereas the prevailing serotypes were 19F (19.3%), 23F (9.6%), 14 (9.6%), 15 (8.9%), and 6A (7.4%). The 7-valent pneumococcal conjugate vaccine (PCV7) and 13-valent pneumococcal conjugate vaccine (PCV13) coverage of the erythromycin-resistant pneumococci among the children younger than five years were 45.2% and 62.2%, respectively. ST320 and serotype 19A pneumococci were common in children aged 0 to 2 years. CC271 was the most frequent clonal complex (CC), which accounts for 24.4% of all erythromycin-resistant isolates. Conclusions: The non-invasive S. pneumoniae in children younger than five years in Beijing presented high and significant resistance rates to erythromycin and tetracycline. The expressions of ermB and tetM genes were the main factors that influence pneumococcal resistance to erythromycin and tetracycline, respectively. Majority of the erythromycin-resistant non-invasive isolates exhibited the cMLSB phenotype and carried the ermB, tetM, xis, and int genes, suggesting the spread of the transposons of the Tn916 family. PCV13 provided higher serotype coverage in the childhood pneumococcal diseases caused by the erythromycin-resistant isolates better than PCV7. Further long-term surveys are required to monitor the molecular characteristics of the erythromycin-resistant S. pneumoniae in children. [ABSTRACT FROM AUTHOR]

An efficient, stereo- and regioselective palladium-catalyzed 6-exo-dig intramolecular hydroarylation of propargyl ethers which provides a concise access to functionalized isochromans in high yields has been developed. A wide range of substrates possessing aromatic, aliphatic and heteroaromatic alkynes can be efficiently transformed into the targeted isochromans. Irrespective of the nature of the substrates, the cyclization follows highly selective stereo- and regiochemistry. [ABSTRACT FROM AUTHOR]

The in vitro activity of ceftobiprole was compared with that of seven antimicrobial agents against invasive Streptococcus pneumoniae isolated from adult patients (>15 years old). Characterization of erythromycin-resistant strains and serotype distribution of all pneumococci were also evaluated. Seventy invasive S. pneumoniae strains were isolated from December 2007 to January 2009. Serotyping was carried out by Quellung reaction. Antibiotic susceptibility was tested by broth microdilution (CLSI guidelines). The comparator agents were penicillin, cefotaxime, erythromycin, clindamycin, telithromycin, tetracycline and moxifloxacin. Phenotypic characterization of macrolide resistance was performed by the double disk method. Macrolide resistance genes [ erm(B) and mef(A/E)] and the promoter of erm(B) were detected by PCR. Twenty-five different serotypes were detected of which 87% were non-PCV7 types. The percentages of resistance to erythromycin, clindamycin and tetracycline were 20%, 8.6% and 16%, respectively. A penicillin MIC ≥0.12 mg/L was observed in 14 of the 70 invasive pneumococci strains. The cefotaxime and ceftobiprole MIC/MIC of these 14 strains were 1/4 and 0.03/1 mg/L, respectively. Ceftobiprole showed higher in vitro activity than penicillin and cefotaxime with all isolates being inhibited by ≤1 mg/L. Its high in vitro activity should make ceftobiprole a very promising drug for the treatment of pneumococcal infections. [ABSTRACT FROM AUTHOR]

Objective: The aims of the study were to investigate antibacterial susceptibility and resistance mechanisms of streptococci isolated from healthy children attending day care units and to evaluate clonal relatedness of the strains. Material and Methods: Antimicrobial susceptibilities of streptococci isolated from 212 children attending 3 different day care units were evaluated using the agar dilution method. Polymerase chain reaction and sequencing were used to investigate resistance mechanisms. Clonal relatedness was evaluated using pulsed field gel electrophoresis. Results: Of 212 children, 11 (5.2%) carried Streptococcus pneumoniae, 17 (8.0%) S. pyogenes, and 42 (19.8%) erythromycin resistant viridans group streptococci. All S. pyogenes were susceptible to penicillin G and macrolides. Ten of 11 clonally unique S. pneumoniae were resistant to penicillin G. Three of 11 S. pneumoniae were macrolide resistant and carried erm(B). Among clonally unique 42 erythromycin resistant viridans group streptococci, 2 (4.8%) had erm(B), 33 (78.6%) had mef(A) and 7 (16.6%) had both erm(B) and mef(A) genes. All S. pyogenes from the first centre and three strains from the second centre were pulse-type A. Conclusion: Among healthy children, colonization with penicillin resistant pneumococci and erythromycin resistant viridans group streptococci is quite high. Clonal spread of S. pyogenes is important for day care units. [ABSTRACT FROM AUTHOR]

Mechanisms by which soluble (i.e., dissolved and colloidal) humic acids (HA) and fulvic acids (FA) alter the transformation kinetics of aromatic substrates by oxidoreductive enzymes such as lignin peroxidase and laccase are not well characterized nor have been quantitatively compared. Hypothesized mechanisms are that soluble HA and FA (1) deactivate the enzyme; (2) act as a competitive substrate; or (3) sequester the aromatic substrate. In this study the transformation of pentachlorophenol (PCP) by purified laccase isolated from Trametes versicolor at 28°C and pH 5.0, in combination with Aldrich HA, Leonardite HA, Suwannee River FA, or Waskish peat FA, were used as a model system to quantitatively test and compare these hypotheses. The four HA and FA did not deactivate laccase after adding catechol as the enzyme's substrate. Slower PCP transformation rates by laccase in the presence of HA and FA were found with higher inhibitor binding constants of HA and FA ( Ki, ranging from 3.63±0.78 to 6.47±1.07 μg mL−1) and sorption coefficients of HA and FA to PCP ( Kdom, log Kdom ranging from 4.09 to 4.81). Comparison of experimental PCP transformation rates in the presence of soluble HA and FA with predicted transformation rates of dissolved PCP (i.e., PCP not associated with soluble HA and FA) indicated that soluble HA and FA modified PCP transformation by lacasse through sequestration and by acting as a competitive substrate. [ABSTRACT FROM AUTHOR]

Macrolide resistance mechanisms in 89 Streptococcus pneumoniae strains isolated from several clinical samples between February 2007 and May 2009 were investigated. Erythromycin resistance was noted in 35 (40%) S. pneumoniae strains. In these strains, the most frequent resistance phenotype was cMLS (74%), and the most frequent resistance genotype was ermB (82%). Both ermB and mefA genes were positive in 20% of macrolide-resistant strains. While no resistance to vancomycin, linezolid and telithromycin was noted in 89 S. pneumoniae strains, 12 (13%) strains were penicillin resistant, 26 (30%) strains were clindamycin resistant, 35 (40%) were azithromycin resistant, 32 (36%) strains were tetracycline resistant, and 1 (1%) strain was levofloxacin resistant. The serotype distribution of 35 macrolide-resistant S. pneumoniae strains revealed that the most frequent serotype was serogroup 19 (45%). Multidrug resistance was present in 19 (86%) of 22 strains carrying only the ermB resistance gene. No clonal dissemination was noted in the macrolide-resistant pneumococcal strains. These findings suggest that macrolide resistance rates, resistance phenotype and genotype, as well as resistant serotypes of S. pneumoniae strains should be continuously monitored in our country. [ABSTRACT FROM AUTHOR]

Infections caused by multiresistant Gram-positive bacteria represent a major health burden in the community as well as in hospitalized patients. Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium are well-known pathogens of hospitalized patients, frequently linked with resistance against multiple antibiotics, compromising effective therapy. Streptococcus pneumoniae and Streptococcus pyogenes are important pathogens in the community and S. aureus has recently emerged as an important community-acquired pathogen. Population genetic studies reveal that recombination prevails as a driving force of genetic diversity in E. faecium, E. faecalis, S. pneumoniae and S. pyogenes, and thus, these species are weakly clonal. Although recombination has a relatively modest role driving the genetic variation of the core genome of S. aureus, the horizontal acquisition of resistance and virulence genes plays a key role in the emergence of new clinically relevant clones in this species. In this review, we discuss the population genetics of E. faecium, E. faecalis, S. pneumoniae, S. pyogenes and S. aureus. Knowledge of the population structure of these pathogens is not only highly relevant for (molecular) epidemiological research but also for identifying the genetic variation that underlies changes in clinical behaviour, to improve our understanding of the pathogenic behaviour of particular clones and to identify novel targets for vaccines or immunotherapy. [ABSTRACT FROM AUTHOR]

Background Antimicrobial use is recognized as a risk factor for Clostridium difficile infection (CDI) and outbreaks. We studied the relationship between PCR ribotype, antimicrobial susceptibility and the genetic basis of resistance in response to exposure to antimicrobial agents. Methods C. difficile isolates were cultured from 133 CDI patients for whom recent antimicrobial drug exposure had been recorded. Isolates were ribotyped by PCR and assessed for their susceptibility to the macrolide–lincosamide–streptogramin B (MLSB) group of compounds (erythromycin and clindamycin) and fluoroquinolone antimicrobials (ciprofloxacin, levofloxacin and moxifloxacin). Where relevant, the genetic basis of resistance was determined. Results Prevalent ribotypes (including 027, 001 and 106) exhibited significantly greater antimicrobial resistance compared with ribotypes 078 and 014, among others. Clindamycin-resistant ribotype 078 was detected for the first time. Ribotypes 027 and 001 were more likely to exhibit MLSB resistance, a feature that was associated with the erm(B) gene. Exposure to MLSB or fluoroquinolone antimicrobial compounds in the 8 weeks prior to the onset of infection was not associated with specific genetic markers of resistance. Single amino acid substitutions in the A and B subunits of DNA gyrase were noted and were ribotype specific and linked to resistance to moxifloxacin. Conclusions Resistance to MLSB and fluoroquinolone antimicrobial compounds is common among prevalent ribotypes of C. difficile. The genetic basis for antimicrobial resistance appears to be ribotype specific and conserved in the absence of recent antimicrobial selection pressure. [ABSTRACT FROM PUBLISHER]

Objectives To analyse the epidemiology of isolates of serotype 6C among invasive pneumococci isolated from children and adults in Spain between 1997 and 2009, and to characterize serotype 6C clones and macrolide and quinolone resistance mechanisms. Methods Antimicrobial susceptibility was determined following CLSI guidelines. Phenotypic characterization of macrolide-resistant isolates was performed by the double disc diffusion method. Genes associated with resistance to erythromycin and tetracycline were sought by PCR, while quinolone resistance was analysed by restriction fragment length polymorphism of the quinolone resistance-determining region. Isolates were typed by multilocus sequence typing. Results Seven hundred and eighty-nine of 866 serotype 6A pneumococci collected from 1997 to 2009 were available. Of these, 213 (27.0%) were serotype 6C; 16/163 (9.8%) in the 1997–2001 (pre-PCV7) period, 37/322 (11.5%) in the 2002–05 (early-PCV7) period and 160/381 (42.0%) in the 2006–09 (late-PCV7) period. The overall proportions of serotype 6C increased from 0.1% (pre-PCV7) to 1% (late-PCV7) for paediatric isolates and from 0.3% to 1.7% among adult isolates. A major serotype 6C lineage (ST224/ST1150/ST4821), accounting for 66.7% of the isolates, was identified across the whole period. In the late-PCV7 period the antimicrobial non-susceptibility of serotype 6C increased in association with the emergence of the ST386/ST4310/ST4825 lineage, which carried a Tn6002 transposon [erm(B) and tet(M) genes]. Conclusions Serotype 6C pneumococci were identified in Spain during the period 1997–2009. The increase in serotype 6C in the late-PCV7 period was associated with the spread of the ST224/ST1150/ST4821 lineage and the emergence of the ST386/ST4310/ST4825 lineage. [ABSTRACT FROM PUBLISHER]