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Abstract: Data from an 800-bed hospital showed an increase in the incidence density of ceftriaxone-resistant Escherichia coli, from 13.1 to 21.7 per 100 000 inpatient days over a 4-year period. Detailed testing performed on 54 E. coli isolates showed bla CTX-M extended-spectrum β-lactamase (ESBL) genes (n = 37) and bla CMY-like ampC genes (n = 15). Typing data showed only limited clonal transmission in isolates with ESBL. [Copyright &y& Elsevier]

• Unexpected high prevalence of mcr-1 in stool specimens of patients attending a tertiary care hospital. • Variable antibioltic-susceptibility profiles of mcr-1 positive Enterobacteriaceae isolates. • No detection of mcr-1 positive carbapenem-resistant Enterobacteriaceae. • First report of the prevalence of human faecal carriage of mcr- 1 in Singapore. The aim of this study was to determine the prevalence of the colistin-resistance gene (mcr-1) and the antibiotic-susceptibility profile of mcr-1 positive, colistin-resistant isolates in stool specimens of patients attending a tertiary care hospital in Singapore. 201 diarrheal stool specimens of patients attending the Changi General Hospital between May to August 2017 were collected and screened for the presence of mcr-1 by culture and molecular methods. Antibiotic-susceptibility profile of mcr -1 positive isolates was determined using the polymyxin B and colistin E-tests and the VITEK 2 system. We observed an unexpectedly high prevalence of mcr-1 in patients attending a tertiary care hospital in Singapore, i.e 6.0% and 8.0% estimated by stool culture and direct stool PCR, respectively. The mcr-1 gene was detected predominantly in Escherichia coli. Antibiotic-susceptibility testing on 12 mcr-1 positive Enterobacteriaceae isolates revealed variable susceptibility profiles with no detection of carbapenem-resistant Enterobacteriaceae. This is the first report of the prevalence of human faecal carriage of mcr- 1 in Singapore. Our findings highlight the potential risk of mcr- 1 spread among our patient cohort. The mcr-1 gene detection combined with the detection of other resistance gene targets of clinical importance is recommended to pre-empt the spread mcr-1 in our patients. [ABSTRACT FROM AUTHOR]

Acute gastroenteritis (AGE) is caused by a wide range of pathogens. Culture methods for the detection of bacterial pathogens is time consuming and labour intensive. This study compared a same-day-to-result commercial molecular method using BD Max™ Enteric Bacterial Panel against conventional culture and laboratory-developed PCR assays (LDTs), and characterised the epidemiology of bacterial AGE in Singapore. PCRs for Campylobacter spp., Salmonella spp., Shigella spp./Enteroinvasive Escherichia coli (EIEC) and Shiga toxin-producing E. coli (STEC)/ Shigella dysenteriae were performed on the BD Max™ platform. Concurrent routine bacterial culture ("reference standard") was performed for Campylobacter , Salmonella , Shigella , Vibrio and Aeromonas spp. In the event of a discrepancy, an "expanded reference standard" (bacterial culture with LDT) was used. There were 299 stool specimens in the study, with no bacterial pathogens detected in 190 samples (63.5%). The positive samples (n = 109,36.5%) were detected with Salmonella (n = 57,19.1%), Campylobacter (n = 28,9.4%), Vibrio parahaemolyticus (n = 6,2.0%), Shigella /EIEC (n = 6,2.0%), ETEC (n = 4,1.3%), STEC (n = 2,0.7%), Aeromonas (n = 2,0.7%), Plesiomonas shigelloides (n = 1,0.3%) and 3(1.0%) co-infections. Compared to the "expanded reference standard", conventional culture missed 38/112 (33.9%) pathogens. Conversely, testing by BD Max™ alone failed to detect 17 pathogens. BD Max™ reported seven (2.3%) false-positive results. BD Max™ increased the detection rate of bacterial AGE pathogens in the panel, but was limited by the absence of detection capability for Vibrio and Aeromonas spp. • Acute gastroenteritis (AGE) is caused by a wide range of pathogens. • Culture methods for bacterial detection are time-consuming and labour intensive. • BD Max™ Enteric Bacterial Panel increases detection yield with shorter turnaround. • Combination of culture for Vibrio and Aeromonas with BD Max™ usage is recommended. [ABSTRACT FROM AUTHOR]

Introduction: This retrospective study investigated the clinical etiology of community-acquired bacteremic Klebsiella pneumoniae infections, and characterized laboratory and genetic markers which may be associated with primary liver abscess (PLA)., Methods: Community-onset K. pneumoniae bacteremic episodes from 2010 to 2011 were identified from the laboratory information system. Isolates were retrieved for susceptibility testing, hypermucoviscosity testing, PCR-based serotyping (K1, K2 and K5) and PCR detection of virulence genes (rmpA, alls, kfu and aerobactin). Clinical data collected from electronic medical records included primary and secondary diagnoses, co-existing morbidities, antibiotic therapy, and in-patient mortality., Results: 129 bacteremic episodes were identified. The most common primary infections were pneumonia (n = 24, 18.6%), primary liver abscess (n = 21, 16.3%) and urinary tract infections (n = 21, 16.3%). Hypermucoviscosity was present in 55 isolates (42.6%). The most commonly detected virulence genes were aerobactin (n = 63, 48.8%) and rmpA (n = 59, 45.7%). Isolates causing liver abscess were significantly associated with a positive string test, rmpA, aerobactin gene, and capsular serotype K1 (all p < 0.01), but not with capsular serotype K2, K5, kfu, or allS genes. The absence of a positive string test, rmpA, or aerobactin genes had a 97.3%-100% negative predictive value for PLA. The positive predictive values of the string test, rmpA, aerobactin genes, and serotype K1 for PLA ranged from 31.7% to 35.6%., Conclusion: In our study population, pneumonia and PLA were the most common sources of community-acquired bacteremia. Hypermucoviscosity, rmpA, aerobactin, and serotype K1 could be useful laboratory markers to alert clinicians to arrange abdominal imaging to detect liver abscess., (Copyright © 2017. Published by Elsevier B.V.)

Introduction: Increasing resistance in Escherichia coli and Klebsiella pneumoniae to firstline antibiotics makes therapeutic options for urinary tract infections (UTIs) challenging. This study investigated the in vitro efficacies of 6 antibiotics against multidrug resistant (MDR) uropathogens., Materials and Methods: Minimum inhibitory concentrations to ceftibuten, cefpodoxime, fosfomycin, mecillinam, temocillin, and trimethoprim were determined against 155 MDR-isolates of E. coli and K. pneumoniae. The presence of extended-spectrum beta-lactamases (ESBL) and plasmid-borne AmpC enzymes was determined by phenotypic testing with genotyping performed by multiplex polymerase chain reaction., Results: Temocillin demonstrated highest susceptibility rates for both E. coli (95%) and K. pneumoniae (95%) when breakpoints for uncomplicated UTIs were applied; however, temocillin susceptibility was substantially lower when "systemic infection" breakpoints were used. Fosfomycin demonstrated the best in vitro efficacy of the orally available agents, with 78% and 69% of E. coli and K. pneumoniae isolates susceptible, respectively. The next most effective antibiotics were ceftibuten (45%) and mecillinam (32%). ESBL and ampC genes were present in 47 (30%) and 59 (38%) isolates., Conclusion: This study demonstrated few oral therapeutic options for MDR-uropathogens, with fosfomycin demonstrating the best in vitro activity.

Various studies have documented a shift in species distribution in Candida bloodstream infections (BSI), but there are little data from Southeast Asia. This study was performed to determine the species epidemiology and antifungal susceptibilities of Candida species BSI in Singapore. Candida spp. from BSI were collected from a tertiary and secondary referral hospital, and an obstetrics/paediatric hospital over a 3-year period. The most common isolates were Candida albicans (36%), Candida tropicalis (27%), Candida glabrata (16%) and Candida parapsilosis (16%). Candida parapsilosis and C. albicans were predominant in the paediatric hospital, and C. albicans and C. tropicalis predominant in the other two institutions. Candida tropicalis temporarily replaced C. albicans as the predominant strain from BSI in 2006. Overall, 87.3% of Candida isolates were susceptible to fluconazole, and 10.4% classified as susceptible-dose-dependent. Fluconazole resistance was detected in C. tropicalis (3.6%), C. parapsilosis (2.1%) and C. glabrata (4.0%). Candida albicans is the predominant species isolated from BSI in Singapore. However, non-albicans species accounted for nearly two-thirds of all cases of candidaemia and the relative increase in C. tropicalis infections deserves further investigation. Resistance to fluconazole was uncommon., (© 2009 Blackwell Verlag GmbH.)

Introduction: Worldwide, Candida albicans is the most common Candida species implicated in bloodstream infections. However, the proportion of non-albicans bloodstream infections is increasing. Fluconazole resistance is known to be more common in non-albicans species, but is also reported in C. albicans. This retrospective study was performed to determine the species epidemiology of Candida bloodstream infections in Singapore hospitals, and to perform susceptibility testing to a range of antifungal drugs., Materials and Methods: Candida spp. isolated from bloodstream infections from October 2004 to December 2006 were collected from 3 participating hospitals: a tertiary referral hospital (Singapore General Hospital), a secondary referral hospital (Changi General Hospital) and an obstetrics/paediatric hospital [KK Women's and Children's Hospital (KKWCH)]. Isolate collection was also retrospectively extended to January 2000 for KKWCH because of the limited number of cases from this hospital. Isolates were identified by a common protocol, and antifungal susceptibility testing was performed by microbroth dilution (Sensititre One, Trek Diagnostics, United Kingdom)., Results: The most common isolates were C. albicans (37%), C. tropicalis (27%) and C. glabrata (16%). There were differences in species distribution between institutions, with C. parapsilosis and C. albicans predominant in KKWCH, and C. albicans and C. tropicalis predominant in the other 2 institutions. Fluconazole resistance was detected in 3.2% of all Candida spp., and 85.3% were classified as susceptible. All C. albicans and C. parapsilosis were susceptible to fluconazole and voriconazole, while susceptibility to fluconazole was much more variable for C. glabrata and C. krusei., Conclusion: This study shows that C. albicans remains the predominant Candida species isolated from bloodstream infections in the 3 participating hospitals. However, non-albicans species accounted for nearly two-thirds of all cases of candidaemia. Resistance to fluconazole was uncommon, and was generally confined to C. krusei and C. glabrata.

Introduction: Antibiotic resistance in gram-negative bacilli is an area of increasing importance. This prospective study was performed to survey antibiotic resistance in Escherichia coli (E. coli), Klebsiella spp., Pseudomonas aeruginosa and Acinetobacter spp. over a 1-year period., Materials and Methods: Non-duplicate isolates of E. coli, Klebsiella spp., P. aeruginosa and Acinetobacter spp. were collected from participating Singapore hospitals during defined collection periods in 2006 and 2007. Confirmatory identification and antibiotic susceptibility testing were performed at Changi General Hospital. Minimum inhibitory concentrations (MIC) to a defined panel of antibiotics were determined using microbroth dilution methods. The presence of extended-spectrum beta lactamases and AmpC beta-lactamases in Enterobacteriaceae was determined by phenotypic methods, and susceptibility results were defined using current breakpoints from the Clinical Laboratory Standards Institute (CLSI)., Results: Seven hundred and forty-six gram-negative bacilli were received for testing. Resistance to extended-spectrum cephalosporins was present in a third of Enterobacteriaceae isolates, and extended-spectrum beta-lactamases (ESBL) carriage was present in 19.6% and 30.1% of E. coli and Klebsiella pneumoniae, respectively. AmpC enzymes were also detected in 8.5% and 5.6% of E. coli and K. pneumoniae isolates respectively. All Enterobacteriaceae were susceptible to imipenem and meropenem. The most active antibiotics against P. aeruginosa were amikacin, meropenem and piperacillin-tazobactam. A third of P. aeruginosa showed reduced susceptibility to polymyxin B. Carbapenem resistance was significantly higher in Acinetobacter baumannii (70.5%) than in other Acinetobacter species (25.0%). The most active antibiotic against A. baumannii was polymyxin B., Conclusion: Antibiotic resistance is prevalent in gram-negative bacilli isolated from Singapore hospitals. The MIC testing surveillance programme complemented susceptibility data from wider laboratory-based surveillance, and has revealed emerging mechanisms of antibiotic resistance.

Introduction: Tigecycline is an antibiotic belonging to the glycylcycline class with in vitro activity against most Gram-negative bacteria, other than Pseudomonas aeruginosa. This study investigated the in vitro activity of tigecycline against multi-resistant isolates of Enterobacteriaceae and Acinetobacter spp. isolated from clinical specimens in Singapore., Materials and Methods: Minimum inhibitory concentrations (MICs) to tigecycline were determined for 173 isolates of multi-resistant Escherichia coli, Klebsiella spp., Enterobacter spp. and Acinetobacter spp. using agar dilution., Results: The MIC required to inhibit the growth of 90% of organisms varied from 0.5 to 4 mg/L for the study isolates. Based on a resistance breakpoint of >or=8 mg/L, resistance rates varied from 0% to 9%., Conclusions: Tigecycline demonstrates good in vitro activity against multi-resistant strains of Enterobacteriaceae, with more variable activity against multi-resistant strains of Acinetobacter spp.