Comparative study of the methods of extracting mesenchymal stem cells from cryopreserved Wharton's Jelly.

The Wharton's Jelly (WJ) is an established source of mesenchymal stem cells (MSC). We compared 3 methods of extracting WJ-MSC from cryopreserved tissue and determined that enzymatic digestion of the WJ yielded the most viable MSC, compared to the explant and mechanical digestion methods. The enzymatically-released WJ-MSC conformed to the International Society for Cellular Therapy (ISCT) criteria: displayed plastic-adherence, co-expressed CD73, CD90, CD105 and were negative for hematopoietic lineage cell markers.

Increasing antibiotic resistance in Streptococcus pneumoniae colonizing children attending day-care centres in Singapore.

BACKGROUND AND OBJECTIVE: Streptococcus pneumoniae is an important cause of morbidity and mortality in both the paediatric and adult population. This study aimed to define pneumococcal colonization rates, and antibiotic resistance patterns across two periods a decade apart, and also assess the serotypes of colonizing strains in children in the era of early pneumococcal conjugate vaccine uptake in Singapore. METHODS: Two cross-sectional prevalence surveys were carried out in 1997 and 2007-2008 on children attending day-care centres across Singapore. Nasopharyngeal swabs were obtained and cultured for S. pneumoniae, and antibiotic susceptibility testing was performed. Serotyping was also done in the 2007-2008 survey. RESULTS: Three hundred and ninety-five children participated in the first survey in 1997, and 418 in the 2007-2008 survey. Pneumococcal colonization rates were 25.8 and 14.1%, respectively. There was a marked increase in antimicrobial non-susceptibility (penicillin 27.4% vs 69.5%; erythromycin 33.4% vs 78%; clindamycin 24.5% vs 45.8%, tetracycline 48% vs 67.8%), and multi-drug resistance (defined as non-susceptibility to three or more classes of antibiotics) increased from 33.3 to 74.6%. In the 2007-2008 survey, serotypes 6B (16.9%), 23F (11.9%) and 19F (10.2%) were most commonly observed. The projected coverage of the 7 and 13-valent conjugate pneumococcal vaccine for colonizing serotypes were 61.9 and 67%, respectively. CONCLUSIONS: S. pneumoniae antibiotic resistance has risen dramatically over the last 10 years in Singapore. Wider conjugate vaccine uptake and improved antibiotic stewardship should be made priorities. Surveillance of sentinel sites like day-care centres provides important data with respect to shifts in pneumococcal ecology.

Comparison of infection rate using different methods of assessment for surveillance of total hip replacement surgical site infections.

BACKGROUND: The surveillance of surgical site infections (SSI) has been undertaken in many centres worldwide to ascertain the extent of the problem and where possible, to improve the incidence rates, thereby decreasing the undesirable outcomes. The study investigates the processes and outcomes of total hip replacement SSI surveillance carried out in Dunedin Public Hospital in 2004. METHODS: Two hundred and six patients were enlisted in the study and 189 primary replacements and 22 revision replacements were carried out. Four methods of diagnosis of SSI were applied: (i) clinician diagnosis; (ii) ASEPSIS score; (iii) presence of pus cells; and (iv) assessment by a clinical microbiologist. Infection rates were calculated according to the risk indexes. RESULTS: The incidence of infections varies considerably among these four methods. The infection rates for risk index 0 were 4.35% (method 1), 2.61% (method 2), 0.87% (methods 3 and 4); and for risk indexes 1 and 2 were 4.17% (method 1), 2.08% (method 2), 1.04% (methods 3 and 4). CONCLUSION: There is a need for accurate infection data so that the appropriate follow-up responses, including infection control measures for total hip replacement SSI can be carried out. The preponderance of elderly patients in the study who are frequently on 'polypharmacy' regimens adds pressure to the need to obtain true infection rates. This is because when antimicrobials are prescribed to them, drug interactions, adverse effects of the antimicrobials and the selective pressure of antimicrobials causing resistances may occur. More resources and a multidisciplinary approach are required for future studies of similar nature.

Antimicrobial drug utilisation in Dunedin Hospital, New Zealand, and its association with antimicrobial resistance.

INTRODUCTION: Antimicrobial resistance (AR) to a drug can be considered a natural response to the selection pressure of that drug, with over prescribing being one of the major causes. Few investigations have evaluated the relationships between antimicrobial drug use in a hospital and antimicrobial resistance. METHOD AND MATERIALS: Antimicrobial drug utilisation (AU) data were collated for Dunedin Hospital, New Zealand, and expressed as defined daily doses per 1000 patient days according to the World Health Organization's definition. The drug groups studied were glycopeptides, carbapenems, third and fourth generation cephalosporins and fluoroquinolones. Antibiograms were also analysed and possible associations between antimicrobial utilisation and resistance were investigated. The reduction of antimicrobial utilisation has also been explored by various means. RESULTS: The utilisation of fluoroquinolones at Dunedin Hospital was high compared with hospitals in South Australia, increasing from 1999 to 2003 then decreasing in 2004 and 2005. The Spearman rank correlation coefficients for the associations between fluoroquinolone utilisation and resistance to ciprofloxacin were: rs = 0.79, p = 0.06 for Pseudomonas aeruginosa and rs = -0.37, p = 0.5 for Escherichia coli. CONCLUSION: The findings of antimicrobial drug utilisation studies in hospital can serve to describe the pattern of drug use in the institution, to detect areas of concern, and to evaluate the impact of interventions taken to influence the use of drugs, especially when this use is associated with increasing antimicrobial drug resistance.

New rapid screen for the detection of imipenem-resistant Acinetobacter baumanii.

A rapid screen was developed for the detection of imipenem-resistant Acinetobacter baumanii (IRAb) following a recent outbreak in the Surgical Intensive Care Unit (SICU) of a hospital in Singapore. Antimicrobial solutions of imipenem ranging from 16 mg/L to 64 mg/L were prepared in-house. Each of the antimicrobial solutions was then incorporated singularly into MacConkey agar plates by two different methods. One of the methods involved preparing MacConkey agar plates in-house and then adding the antimicrobial solution before the agar solidified (AS method). In the second method, 1 ml of the antimicrobial solution was poured onto the surface of the agar plate (LAS method). Fifty hand-nutrient broth washes of medical staff working in the SICU, Medical Intensive Care Unit, Medical Rehabilitation Ward, and Surgical Rehabilitation Ward were inoculated onto the two types of agar media. Two strains of IRAb were isolated from the hands. The LAS plates showed faster bacterial growth of resistant pathogens by about 24 h, and their detection was easier because susceptible bacteria were inhibited by the antimicrobial. The LAS method incorporating imipenem at 32 mg/L is recommended for the rapid screening of resistant pathogens in the routine clinical laboratory.