Determining the effect of gene deletion is a fundamental approach to understanding gene function. Conventional genetic screens exhibit biases, and genes contributing to a phenotype are often missed. We systematically constructed a nearly complete collection of gene-deletion mutants (96% of annotated open reading frames, or ORFs) of the yeast Saccharomyces cerevisiae. DNA sequences dubbed 'molecular bar codes' uniquely identify each strain, enabling their growth to be analysed in parallel and the fitness contribution of each gene to be quantitatively assessed by hybridization to high-density oligonucleotide arrays. We show that previously known and new genes are necessary for optimal growth under six well-studied conditions: high salt, sorbitol, galactose, pH 8, minimal medium and nystatin treatment. Less than 7% of genes that exhibit a significant increase in messenger RNA expression are also required for optimal growth in four of the tested conditions. Our results validate the yeast gene-deletion collection as a valuable resource for functional genomics.

Our findings confirmed that MRSA infections in the community have been increasing in Asian countries. Data also suggest that various MRSA clones have spread between the community and hospitals as well as between countries.

Isolates from Hong Kong showed the highest rate of ciprofloxacin resistance (11.8%), followed by isolates from Sri Lanka (9.5%), the Philippines (9.1%), and Korea (6.5%). Multilocus sequence typing showed that the spread of the Taiwan 19F clone and the Spain 23F clone could be one of the major reasons for the rapid increases in antimicrobial resistance among S. pneumoniae isolates in Asia. Data from the multinational surveillance study clearly documented distinctive increases in the prevalence rates and the levels of antimicrobial resistance among S. pneumoniae isolates in many Asian countries, which are among the highest in the world published to date.The global emergence of in vitro antimicrobial resistance in Streptococcus pneumoniae has become a serious clinical concern since the 1980s (1). During the past two decades, the rates of resistance to penicillin, other beta-lactams, and non-betalactam agents have been increasing rapidly in many parts of the world. In particular, data on rates of pneumococcal resistance from Asian countries at the end of the 1990s were alarming.

Antimicrobial resistance in

Background Improving the quality of hospital antibiotic use is a major goal of WHO's global action plan to combat antimicrobial resistance. The WHO Essential Medicines List Access, Watch, and Reserve (AWaRe) classification could facilitate simple stewardship interventions that are widely applicable globally. We aimed to present data on patterns of paediatric AWaRe antibiotic use that could be used for local and national stewardship interventions. Methods 1-day point prevalence survey antibiotic prescription data were combined from two independent global networks: the Global Antimicrobial Resistance, Prescribing, and Efficacy in Neonates and Children and the Global Point Prevalence Survey on Antimicrobial Consumption and Resistance networks. We included hospital inpatients aged younger than 19 years receiving at least one antibiotic on the day of the survey. The WHO AWaRe classification was used to describe overall antibiotic use as assessed by the variation between use of Access, Watch, and Reserve antibiotics, for neonates and children and for the commonest clinical indications. Findings Of the 23 572 patients included from 56 countries, 18 305 were children (77•7%) and 5267 were neonates (22•3%). Access antibiotic use in children ranged from 7•8% (China) to 61•2% (Slovenia) of all antibiotic prescriptions. The use of Watch antibiotics in children was highest in Iran (77•3%) and lowest in Finland (23•0%). In neonates, Access antibiotic use was highest in Singapore (100•0%) and lowest in China (24•2%). Reserve antibiotic use was low in all countries. Major differences in clinical syndrome-specific patterns of AWaRe antibiotic use in lower respiratory tract infection and neonatal sepsis were observed between WHO regions and countries. Interpretation There is substantial global variation in the proportion of AWaRe antibiotics used in hospitalised neonates and children. The AWaRe classification could potentially be used as a simple traffic light metric of appropriate antibiotic use. Future efforts should focus on developing and evaluating paediatric antibiotic stewardship programmes on the basis of the AWaRe index.

Field studies of Streptococcus pneumoniae (pneumococci) nasopharyngeal (NP) colonization are hampered by the need to directly plate specimens in order to ensure isolate viability. A medium containing skim milk, tryptone, glucose, and glycerin (STGG) has been used to transport and store NP material, but its ability to preserve pneumococci has not been evaluated. Our objective was to qualitatively and semiquantitatively evaluate the ability of STGG to preserve pneumococci in NP secretions. Entwined duplicate calcium alginate NP swab samples were obtained from children. One swab was plated directly onto a gentamicin blood agar plate; the other was placed in STGG. Growth from the directly plated specimen was compared with growth from an STGG aliquot immediately cultured or stored at ؊70°C for 9 weeks, ؊20°C for 9 weeks, or 4°C for 5 days. Of 186 specimens, 96 (52%) were positive for pneumococci from the direct plating; 94 (98%) of these were positive from the fresh STGG specimen. Pneumococci were recovered from all 38 positive specimens frozen at ؊70°C, all 18 positive specimens frozen at ؊20°C, and 18 of 20 positive specimens stored at 4°C. Recovery of pneumococci after storage of NP material in STGG medium at ؊70°C is at least as good as that from direct plating. Storage at ؊20°C is also acceptable. Storage at 4°C for 5 days is not ideal.Streptococcus pneumoniae (pneumococci) is the most important cause of bacterial otitis media, pneumonia, bacteremia, and meningitis among children worldwide (12,15,17). Pneumococci are also important because the rate of nonsusceptibility to various classes of antimicrobial agents, such as penicillins and cephalosporins, is rising throughout the United States and worldwide (4,18,19). Prevention efforts have been hampered by the lack of a vaccine which is immunogenic for important serotypes in children younger than 2 years of age. A seven-valence pneumococcal conjugate vaccine (Prevnar; Wyeth Lederle Vaccines) which is immunogenic and efficacious in this age group recently has been licensed in the United States for use among children through 9 years of age and is recommended routinely for those under 2 years of age (1, 3, 16). The effect of this and other conjugate pneumococcal vaccines on nasopharyngeal (NP) colonization is a subject of intense investigation.It is well known that pneumococci are spread from person to person via the respiratory route. NP colonization studies have shown that people acquire pneumococci at a young age, carry these organisms for various periods of time, may carry more than one serotype at a time, and transmit these organisms to others with whom they are in close contact (2,5,(9)(10)(11)14). Many studies of the dynamics and ecology of pneumococcal NP carriage, particularly in the setting of new conjugate pneumococcal vaccines, will be performed in settings where microbiologic facilities are not readily available.An optimal medium has not been validated for the transport, preservation, and recovery of pneumococci from NP material. One medium, STGG (skim m...

Expression of a capsular polysaccharide is considered a hallmark of most invasive species of bacteria, including Streptococcus pneumoniae, in which the capsule is among the principal virulence factors and is the basis for successful vaccines. Consequently, it was previously assumed that capsule production distinguishes S. pneumoniae from closely related commensals of the mitis group streptococci. Based on antigenic and genetic analyses of 187 mitis group streptococci, including 90 recognized serotypes of S. pneumoniae, we demonstrated capsule production by the Wzy/Wzx pathway in 74% of 66 S. mitis strains and in virtually all tested strains of S. oralis (subspecies oralis, dentisani, and tigurinus) and S. infantis. Additional analyses of genomes of S. cristatus, S. parasanguinis, S. australis, S. sanguinis, S. gordonii, S. anginosus, S. intermedius, and S. constellatus revealed complete capsular biosynthesis (cps) loci in all strains tested. Truncated cps loci were detected in three strains of S. pseudopneumoniae, in 26% of S. mitis strains, and in a single S. oralis strain. The level of sequence identities of cps locus genes confirmed that the structural polymorphism of capsular polysaccharides in S. pneumoniae evolved by import of cps fragments from commensal Streptococcus species, resulting in a mosaic of genes of different origins. The demonstrated antigenic identity of at least eight of the numerous capsular polysaccharide structures expressed by commensal streptococci with recognized serotypes of S. pneumoniae raises concerns about potential misidentifications in addition to important questions concerning the consequences for vaccination and host-parasite relationships both for the commensals and for the pathogen.

Data confirm that macrolide resistance in pneumococci is a serious problem in many Asian countries.