Acquired Carbapenemases in Gram-Negative Bacilli in Singapore

Ph.DDOCTOR OF PHILOSOPH

Streptococcus iniae Discitis in Singapore

10.3201/eid1009.040029Emerging Infectious Diseases1091694-169

CTX-M and Plasmid-mediated AmpC-Producing Enterobacteriaceae, Singapore

10.3201/eid1006.030726Emerging Infectious Diseases1061172-117

Panton-Valentine Leukocidin–positive Staphylococcus aureus, Singapore

10.3201/eid1008.031088Emerging Infectious Diseases1081509-151

A Method for generating marker-less gene deletions in multidrug-resistant Acinetobacter baumannii

10.1186/1471-2180-13-158BMC Microbiology131581-1

Antimicrobial Drug Resistance in Singapore Hospitals

A new national antimicrobial resistance surveillance program in Singapore public hospitals that uses WHONET detected high levels of methicillin resistance among Staphylococcus aureus (35.3%), carbapenem resistance among Acinetobacter spp. (49.6%), and third-generation cephalosporin resistance among Klebsiella pneumoniae (35.9%) hospital isolates in 2006. Antimicrobial drug resistance is a major problem in Singapore

Decline in Clostridium difficile-associated disease rates in Singapore public hospitals, 2006 to 2008

<p>Abstract</p> <p>Background</p> <p><it>Clostridium difficile </it>is the major cause of pseudomembranous colitis associated with antibiotic use, and the spread of the hypervirulent epidemic ribotype 027/NAP-1 strain across hospitals worldwide has re-focused attention on this nosocomial pathogen. The overall incidence and trend of <it>C. difficile</it>-associated disease (CDAD) in Singapore is unknown, and a surveillance program to determine these via formal laboratory-based reporting was established.</p> <p>Findings</p> <p>Laboratory and pharmacy data were collated from one tertiary and two secondary hospitals on a quarterly basis between 2006 and 2008. All hospitals tested for <it>C. difficile </it>using Immunocard Toxins A&B (Meridian Bioscience Inc., Cincinnati, OH) during this period. Duplicate positive <it>C. difficile </it>results within a 14-day period were removed. The CDAD results were compared with trends in hospital-based prescription of major classes of antibiotics.</p> <p>Overall CDAD incidence-density decreased from 5.16 (95%CI: 4.73 - 5.62) cases per 10,000 inpatient-days in 2006 to 2.99 (95%CI: 2.67 to 3.33) cases per 10,000 inpatient-days in 2008 (<it>p </it>< 0.001), while overall rates for <it>C. difficile </it>testing increased significantly (<it>p </it>< 0.001) within the same period. These trends were mirrored at the individual hospital level. Evaluation of antibiotic prescription data at all hospitals showed increasing use of carbapenems and fluoroquinolones, while cephalosporin and clindamycin prescription remained stable.</p> <p>Conclusions</p> <p>Our results demonstrate a real decline of CDAD rates in three large local hospitals. The cause is unclear and is not associated with improved infection control measures or reduction in antibiotic prescription. Lack of <it>C. difficile </it>stool cultures as part of routine testing precluded determination of the decline of a major clone as a potential explanation. For more accurate epidemiological trending of CDAD and early detection of epidemic clones, data collection will have to be expanded and resources set in place for reference laboratory culture and typing.</p

Community-associated Methicillin-resistant Staphylococcus aureus, Singapore

10.3201/eid1102.040782Emerging Infectious Diseases112341-34

Evolutionary dynamics of methicillin-resistant Staphylococcus aureus within a healthcare system

Background: In the past decade, several countries have seen gradual replacement of endemic multi-resistant healthcare-associated methicillin-resistant Staphylococcus aureus (MRSA) with clones that are more susceptible to antibiotic treatment. One example is Singapore, where MRSA ST239, the dominant clone since molecular profiling of MRSA began in the mid-1980s, has been replaced by ST22 isolates belonging to EMRSA-15, a recently emerged pandemic lineage originating from Europe.Results: We investigated the population structure of MRSA in Singaporean hospitals spanning three decades, using whole genome sequencing. Applying Bayesian phylogenetic methods we report that prior to the introduction of ST22, the ST239 MRSA population in Singapore originated from multiple introductions from the surrounding region; it was frequently transferred within the healthcare system resulting in a heterogeneous hospital population. Following the introduction of ST22 around the beginning of the millennium, this clone spread rapidly through Singaporean hospitals, supplanting the endemic ST239 population. Coalescent analysis revealed that although the genetic diversity of ST239 initially decreased as ST22 became more dominant, from 2007 onwards the genetic diversity of ST239 began to increase once more, which was not associated with the emergence of a sub-clone of ST239. Comparative genomic analysis of the accessory genome of the extant ST239 population identified that the Arginine Catabolic Mobile Element arose multiple times, thereby introducing genes associated with enhanced skin colonization into this population.Conclusions: Our results clearly demonstrate that, alongside clinical practice and antibiotic usage, competition between clones also has an important role in driving the evolution of nosocomial pathogen populations.</p

ST3268 : a geographically widespread primate MRSA clone

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