Progress towards a coordinated, national paediatric antimicrobial resistance surveillance programme: Staphylococcus aureus, enterococcal and Gram-negative bacteraemia in Australia.

BACKGROUND: There is increasing knowledge of antimicrobial usage in children yet limited availability of nationally representative paediatric-specific data on antimicrobial resistance. OBJECTIVES: Paediatric data from this national surveillance programme are presented to explore differences between childhood and adult bloodstream infections and antimicrobial resistance surveillance. METHODS: Using information collected from a prospective coordinated antimicrobial resistance surveillance programme, children ≤18 years and adults >18 years with a positive blood culture for Staphylococcus aureus, Enterococcus spp. or Gram-negative spp. presenting to one of 34 Australian hospitals during 2013-16 were evaluated. Consistent methodologies for key sepsis pathogens were employed and a comparative analysis between children and adults was conducted. RESULTS: There are stark contrasts between children and adults in this national antimicrobial resistance (AMR) data set. Notable differences include lower rates of AMR, different clinical and molecular phenotypes and lower mortality amongst children. The burden of Gram-negative resistance is disproportionately experienced in children, with higher odds of death with an ESBL versus non-ESBL bacteraemia in comparison with adults. CONCLUSIONS: These data support that children are not just 'little adults' in the AMR era, and analyses by age group are important to detect differences in antibiotic susceptibility, clinical phenotype and genetic virulence factors. Antimicrobial surveillance incorporated into routine laboratory practice is vital to inform an array of wider applications including antimicrobial guidelines, stewardship and direction for prioritization of novel antimicrobial development.

Phylogenetic diversity, antimicrobial susceptibility and virulence characteristics of phylogroup F Escherichia coli in Australia.

Unlike Escherichia coli strains belonging to phylogroup B2, the clinical significance of strains belonging to phylogroup F is not well understood. Here we report on a collection of phylogroup F strains recovered in Australia from faeces and extra-intestinal sites from humans, companion animals and native animals, as well as from poultry meat and water samples. The distribution of sequence types was clearly non-random with respect to isolate source. The antimicrobial resistance and virulence trait profiles also varied with the sequence type of the isolate. Phylogroup F strains tended to lack the virulence traits typically associated with phylogroup B2 strains responsible for extra-intestinal infection in humans. Resistance to fluoroquinolones and/or expanded-spectrum cephalosporins was common within ST648, ST354 and ST3711. Although ST354 and ST3711 are part of the same clonal complex, the ST3711 isolates were only recovered from native birds being cared for in a single wildlife rehabilitation centre, whereas the ST354 isolates were from faeces and extra-intestinal sites of dogs and humans, as well as from poultry meat. Although ST354 isolates from chicken meat in Western Australia were distinct from all other ST354 isolates, those from poultry meat samples collected in eastern Australia shared many similarities with other ST354 isolates from humans and companion animals.

Australian Group on Antimicrobial Resistance Australian Enterobacteriaceae Sepsis Outcome Programme annual report, 2014.

The Australian Group on Antimicrobial Resistance performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric Gram-negative pathogens. The 2014 survey was the second year to focus on blood stream infections. During 2014, 5,798 Enterobacteriaceae species isolates were tested using commercial automated methods (Vitek 2, BioMérieux; Phoenix, BD) and results were analysed using the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints (January 2015). Of the key resistances, non-susceptibility to the third-generation cephalosporin, ceftriaxone, was found in 9.0%/9.0% of Escherichia coli (CLSI/EUCAST criteria) and 7.8%/7.8% of Klebsiella pneumoniae, and 8.0%/8.0% K. oxytoca. Non-susceptibility rates to ciprofloxacin were 10.4%/11.6% for E. coli, 5.0%/7.7% for K. pneumoniae, 0.4%/0.4% for K. oxytoca, and 3.5%/6.5% in Enterobacter cloacae. Resistance rates to piperacillin-tazobactam were 3.2%/6.8%, 4.8%/7.2%, 11.1%/11.5%, and 19.0%/24.7% for the same 4 species respectively. Fourteen isolates were shown to harbour a carbapenemase gene, 7 blaIMP-4, 3 blaKPC-2, 3 blaVIM-1, 1 blaNDM-4, and 1 blaOXA-181-lke.

Australian Group on Antimicrobial Resistance Australian Enterococcal Sepsis Outcome Programme annual report, 2014.

From 1 January to 31 December 2014, 27 institutions around Australia participated in the Australian Enterococcal Sepsis Outcome Programme (AESOP). The aim of AESOP 2014 was to determine the proportion of enterococcal bacteraemia isolates in Australia that were antimicrobial resistant, and to characterise the molecular epidemiology of the Enterococcus faecium isolates. Of the 952 unique episodes of bacteraemia investigated, 94.4% were caused by either E. faecalis (54.9%) or E. faecium (39.9%). Ampicillin resistance was detected in 0.6% of E. faecalis and in 89.4% of E. faecium. Vancomycin non-susceptibility was reported in 0.2% and 46.1% of E. faecalis and E. faecium respectively. Overall 51.1% of E. faecium harboured vanA or vanB genes. For the vanA/B positive E. faecium isolates, 81.5% harboured vanB genes and 18.5% vanA genes. The percentage of E. faecium bacteraemia isolates resistant to vancomycin in Australia is significantly higher than that seen in most European countries. E. faecium consisted of 113 pulsed-field gel electrophoresis pulsotypes of which 68.9% of isolates were classified into 14 major pulsotypes containing 5 or more isolates. Multilocus sequence typing grouped the 14 major pulsotypes into clonal cluster 17, a major hospital-adapted polyclonal E. faecium cluster. The geographical distribution of the 4 predominant sequence types (ST203, ST796, ST555 and ST17) varied with only ST203 identified across most regions of Australia. Overall 74.7% of isolates belonging to the four predominant STs harboured vanA or vanB genes. In conclusion, the AESOP 2014 has shown enterococcal bacteraemias in Australia are frequently caused by polyclonal ampicillin-resistant high-level gentamicin resistant vanA or vanB E. faecium, which have limited treatment options.

Australian Group on Antimicrobial Resistance Australian Staphylococcus aureus Sepsis Outcome Programme annual report, 2014.

From 1 January to 31 December 2014, 27 institutions around Australia participated in the Australian Staphylococcal Sepsis Outcome Programme (ASSOP). The aim of ASSOP 2014 was to determine the proportion of Staphylococcus aureus bacteraemia (SAB) isolates in Australia that are antimicrobial resistant, with particular emphasis on susceptibility to methicillin and to characterise the molecular epidemiology of the isolates. Overall, 18.8% of the 2,206 SAB episodes were methicillin resistant, which was significantly higher than that reported in most European countries. The 30-day all-cause mortality associated with methicillin-resistant SAB was 23.4%, which was significantly higher than the 14.4% mortality associated with methicillin-sensitive SAB (P <0.0001). With the exception of the beta-lactams and erythromycin, antimicrobial resistance in methicillin-sensitive S. aureus remains rare. However in addition to the beta-lactams, approximately 50‰ of methicillin-resistant S. aureus (MRSA) were resistant to erythromycin and ciprofloxacin and approximately 15% were resistant to co-trimoxazole, tetracycline and gentamicin. When applying the European Committee on Antimicrobial Susceptibility Testing breakpoints, teicoplanin resistance was detected in 2 S. aureus isolates. Resistance was not detected for vancomycin or linezolid. Resistance to non-beta-lactam antimicrobials was largely attributable to 2 healthcare-associated MRSA clones; ST22-IV [2B] (EMRSA-15) and ST239-III [3A] (Aus-2/3 EMRSA). ST22-IV [2B] (EMRSA-15) has become the predominant healthcare associated clone in Australia. Sixty per cent of methicillin-resistant SAB were due to community-associated (CA) clones. Although polyclonal, almost 44% of community-associated clones were characterised as ST93-IV [2B] (Queensland CA-MRSA) and ST1-IV [2B] (WA1). CA-MRSA, in particular the ST45-V [5C2&5] (WA84) clone, has acquired multiple antimicrobial resistance determinants including ciprofloxacin, erythromycin, clindamycin, gentamicin and tetracycline. As CA-MRSA is well established in the Australian community it is important that antimicrobial resistance patterns in community and healthcare-associated SAB is monitored as this information will guide therapeutic practices in treating S. aureus sepsis.

Performance of phenotypic tests for detection of penicillinase in Staphylococcus aureus isolates from Australia.

Recent studies have shown that chromogenic cephalosporin tests are inferior to disc zone edge tests in detecting penicillinase in Staphylococcus aureus isolates, resulting in a change to CLSI and EUCAST guidelines in 2012. We sought to confirm these findings using Australian isolates and compare the performance of the CLSI and EUCAST methods, which use different disc strengths, penicillin at 10 units (P10) and 1 unit (P1), respectively. Using blaZ PCR as the reference standard, the sensitivities of the tests for detection of penicillinase production were as follows: Cefinase disc test, 24/38 isolates (63%); P10 disc zone edge test, 34/38 isolates (89%); P10 disc diameter test, 25/38 isolates (66%); P1 disc zone edge test, 38/38 isolates (100%); and P1 disc diameter test, 38/38 isolates (100%). We also found that the P10 disc zone edge test reading was interpreted differently by the clinical laboratory and the study investigators in 11% of instances. Our findings support those of previous studies showing that chromogenic cephalosporin-based ß-lactamase tests are inferior to disc methods in detecting S. aureus penicillinase. We also conclude that the EUCAST method using the P1 disc has the best performance, particularly because the P1 disc zone diameter reading closely correlated with penicillinase production and reading of the disc zone diameter is less subjective than reading of the zone edge.

Hospital-onset Gram-negative Surveillance Program annual report, 2011.

The Australian Group on Antimicrobial Resistance performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric Gram-negative pathogens. The 2011 survey focussed on hospital-onset infections, examining isolates from all specimens presumed to be causing disease. In 2011, 1,827 Escherichia coli, 537 Klebsiella species and 269 Enterobacter species were tested using a commercial automated method (Vitek 2, BioMérieux) and results were analysed using Clinical and Laboratory Standards Institute breakpoints from January 2012. Of the key resistances, non-susceptibilty to the third-generation cephalosporin, ceftriaxone, was found in 9.6% of E. coli and 9.5%-12.1% of Klebsiella spp. Non-susceptibility rates to ciprofloxacin were 10.6% for E. coli, 0.0%-8.3% for Klebsiella spp. and 0.0%-5.0% in Enterobacter spp. Resistance rates to gentamicin were 8.6%, 2.9%-10.9%, and 0.0%-15.6% for the same 3 groups respectively. Eight strains, 5 Klebsiella spp. and 3 Enterobacter spp. were shown to harbour a carbapenemase (IMP-4).

Community-onset Gram-negative Surveillance Program annual report, 2012.

The Australian Group on Antimicrobial Resistance performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric Gram-negative pathogens. The 2012 survey focussed on community-onset infections, examining isolates from urinary tract infections from patients presenting to outpatient clinics, emergency departments or to community practitioners. In 2012, 2,025 Escherichia coli, 538 Klebsiella species and 239 Enterobacter species were tested using a commercial automated method (Vitek 2, BioMérieux) and results were analysed using Clinical and Laboratory Standards Institute breakpoints from January 2012. Of the key resistances, non-susceptibility to the third-generation cephalosporin, ceftriaxone, was found in 4.2% of E. coli and 4.6%-6.9% of Klebsiella spp. Non-susceptibility rates to ciprofloxacin were 6.9% for E. coli, 0.0%-3.5% for Klebsiella spp. and 0.8%-1.9% in Enterobacter spp, and resistance rates to piperacillin-tazobactam were 1.7%, 0.7%-9.2%, and 8.8%-11.4% for the same 3 groups respectively. Only 1 Enterobacter cloacae was shown to harbour a carbapenemase (IMP-4).

Enterobacteriaceae Sepsis Outcome Programme annual report, 2013.

The Australian Group on Antimicrobial Resistance performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric Gram-negative pathogens. The 2013 survey focussed for the first time on blood stream infections. Four thousand nine hundred and fifty-eight Enterobacteriaceae species were tested using commercial automated methods (Vitek® 2, BioMérieux; Phoenix™, BD). The results were analysed using Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints (January 2014). Of the key resistances, non-susceptibility to the third-generation cephalosporin, ceftriaxone, was found in 7.5%/7.5% (CLSI/EUCAST criteria respectively) of Escherichia coli; 6.3%/6.3% of Klebsiella pneumoniae, and 7.4%/7.4% of K. oxytoca. Non-susceptibility rates to ciprofloxacin were 10.3%/11.3% for E. coli, 4.6%/7.5% for K. pneumoniae, 0.6%/0.6% for K. oxytoca, and 3.6%/6.1% in Enterobacter cloacae. Resistance rates to piperacillin-tazobactam were 3.1%/6.2%, 4.2%/7.0%, 11.9% /12.6%, and 17.3% /22.2% for the same 4 species respectively. Fourteen isolates were shown to harbour a carbapenemase gene, 9 blaIMP, 3 blaKPC, and 2 blaNDM.

Regional resistance surveillance program results for 12 Asia-Pacific nations (2011).

The Regional Resistance Surveillance program monitored susceptibility rates and developing resistance by geographic region, including 12 Asia-Pacific (APAC) countries. Reference broth microdilution methods for susceptibility/interpretations were applied, processing 5,053 strains. Among Staphylococcus aureus isolates (37% methicillin-resistant S. aureus [MRSA], highest in South Korea [73%]), linezolid (LZD), tigecycline (TIG), and vancomycin were 100% active, but 33 and 34% of strains were levofloxacin (LEV) or macrolide resistant, respectively. Streptococcus pneumoniae was most resistant to ß-lactams and macrolides (45%) but was LZD, LEV, and TIG susceptible (>98%). Extended-spectrum ß-lactamase (ESBL) phenotype rates in Escherichia coli and Klebsiella spp. were 48 and 47%, respectively, and were highest in Taiwan, at 75 to 91%. The best anti-ESBL-phenotype agents were amikacin (81 to 96% susceptible), colistin (COL; >98%), TIG (>98%), and carbapenems (81 to 97%). Pseudomonas aeruginosa showed ≥20% resistance to all drugs except COL (99% susceptible). In conclusion, endemic evolving antimicrobial resistances in APAC nations show compromised roles for many commonly used antimicrobials.

"Down the drain": carbapenem-resistant bacteria in intensive care unit patients and handwashing sinks.

OBJECTIVES: Clinical utility of carbapenem antibiotics is under threat because of the emergence of acquired metallo-ß-lactamase (MBL) genes. We describe an outbreak in an intensive care unit (ICU) possibly associated with contaminated sinks. DESIGN, SETTING AND PARTICIPANTS: Four clusters of gram-negative bacteria harbouring the MBL gene blaIMP-4 were detected in the ICU at Dandenong Hospital between November 2009 and July 2012. Epidemiological investigations were undertaken in order to identify a common point source. During September 2012, screening using rectal swabs for all ICU patients, and environmental swabs targeting all ICU handwashing sinks and taps were collected. Samples were cultured onto selective carbapenem-resistant Enterobacteriaceae (CRE) agar. Suspected CRE isolates were further characterised using the modified Hodge test and VITEK 2 and confirmed by polymerase chain reaction and sequencing of MBL genes. Clinical and environmental CRE isolates were typed by pulsed-field gel electrophoresis. RESULTS: Ten clinical isolates and one screening isolate of CRE (consisting of Klebsiella pneumoniae [5], Serratia marcescens [4], Enterobacter cloacae [1] and Escherichia coli [1]) were detected with the blaIMP-4 gene over the 30-03 period. S. marcescens was isolated persistently from the grating and drain of eight central sinks. Molecular typing confirmed that clinical and environmental isolates were related. Tap water cultures were negative. Several attempts to clean and decontaminate the sinks using detergents and steam cleaning proved unsuccessful. CONCLUSION: This report highlights the importance of identification of potential environmental reservoirs, such as sinks, for control of outbreaks of environmentally hardy multiresistant organisms.

Australian Group on Antimicrobial Resistance Hospital-onset Staphylococcus aureus Surveillance Programme annual report, 2011.

In 2011, the Australian Group on Antimicrobial Resistance (AGAR) conducted a period-prevalence survey of clinical Staphylococcus aureus isolated from hospital inpatients. Twenty-nine microbiology laboratories from all states and mainland territories participated. Specimens were collected more than 48 hours post-admission. Isolates were tested by Vitek2® antimicrobial susceptibility card (AST-P612 card). Nationally, the proportion of S. aureus that were methicillin-resistant S. aureus (MRSA) was 30.3%; ranging from 19.9% in Western Australia to 36.8% in New South Wales/Australian Capital Territory. Resistance to the non-ß-lactam antimicrobials was common except for rifampicin, fusidic acid, high-level mupirocin and daptomycin. No resistance was detected for vancomycin, teicoplanin or linezolid. Antibiotic resistance in methicillin susceptible S. aureus (MSSA) was rare apart from erythromycin (13.2%) and there was no resistance to vancomycin, teicoplanin or linezolid. Inducible clindamycin resistance was the norm for erythromycin resistant, clindamycin intermediate/susceptible S. aureus in Australia with 90.6% of MRSA and 83.1% of MSSA with this phenotype having a positive double disc diffusion test (D-test). The proportion of S. aureus characterised as being healthcare-associated MRSA (HA-MRSA) was 18.2%, ranging from 4.5% in Western Australia to 28.0% in New South Wales/Australian Capital Territory. Four HA-MRSA clones were characterised and 98.8% of HA-MRSA isolates were classified as either ST22-IV [2B] (EMRSA-15) or ST239-III [3A] (Aus-2/3 EMRSA). Multiclonal community-associated MRSA (CA-MRSA) accounted for 11.7% of all S. aureus. In Australia, regional variation in resistance is due to the differential distribution of MRSA clones between regions, particularly for the major HA-MRSA clone, ST239-III [3A] (Aus-2/3 EMRSA), which is resistant to multiple non-ß-lactam antimicrobials.

Australian Group on Antimicrobial Resistance Enterococcus Surveillance Programme annual report, 2010.

In 2010, 15 institutions around Australia conducted a period prevalence study of key resistances in isolates of Enterococcus species associated with a range of clinical disease amongst in- and outpatients. Each institution collected up to 100 consecutive isolates and tested these for susceptibility to commonly used antimicrobials using standardised methods. Vancomycin-resistant Enterococcus faecium and Enterococcus faecalis were characterised by pulsed-field gel electrophoresis. Multilocus sequence typing was performed on representative pulsotypes of E. faecium. Susceptibility results were compared with similar surveys conducted in 1995, 1999, 2003, 2005, 2007 and 2009. In the 2010 survey, E. faecalis (1,201 isolates) and E. faecium (170 isolates) made up 98.9% of the 1,386 isolates tested. Ampicillin resistance was very common (85.3%) in E. faecium and absent in E. faecalis. Non-susceptibility to vancomycin was 36.5% in E. faecium (similar to the 35.2% in 2009 but up from 15.4% in the 2007 survey) and 0.5% in E. faecalis. There were significant differences in the proportion of vancomycin-resistant E. faecium between the states ranging from 0% in Western Australia to 54.4% in South Australia. The vanB gene was detected in 62 E. faecium and 3 E. faecalis isolates. The vanA gene was detected in 1 E. faecium isolate. All vancomycin-resistant E. faecium belonged to clonal complex 17. The most common sequence type (ST) was ST203, which was found in all regions that had reports of vancomycin resistant enterococci. ST341 was detected only in New South Wales/Australian Capital Territory and ST414 only in South Australia and Victoria. High-level resistance to gentamicin was 34.1% in E. faecalis and 66.1% in E. faecium. A subset of isolates was tested against high-level streptomycin, linezolid and quinupristin/dalfopristin. High-level streptomycin resistance was found in 8.2% of E. faecalis isolates and 43.8% of E. faecium isolates. Linezolid non-susceptibility was more common in E. faecalis (5.8%) than E. faecium (0.9%). Overall 9.4% of E. faecium were resistant to quinupristin/dalfopristin (E. faecalis is intrinsically resistant).

Australian Group on Antimicrobial Resistance Community-onset Gram-negative Surveillance Program annual report, 2010.

The Australian Group on Antimicrobial Resistance (AGAR) performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric Gram-negative pathogens. The 2010 survey focussed on community-onset infections, examining isolates from urinary tract infections from patients presenting to outpatient clinics, emergency departments or to community practitioners. Two thousand and ninety-two Escherichia coli, 578 Klebsiella species and 268 Enterobacter species were tested using a commercial automated method (Vitek 2, BioMérieux) and results were analysed using Clinical and Laboratory Standards Institute breakpoints from January 2012. Of the key resistances, non-susceptibility to the third-generation cephalosporin, ceftriaxone, was found in 3.2% of E. coli and 3.2%-4.0% of Klebsiella spp. Non-susceptibility rates to ciprofloxacin were 5.4% for E. coli, 1.0%-2.3% for Klebsiella spp., and 2.5%-6.6% in Enterobacter spp, and resistance rates to piperacillin-tazobactam were 2.8%, 3.2%-6.9%, and 16.8%-18.0% for the same 3 groups respectively. Only 3 strains, 2 Klebsiella spp. and 1 Enterobacter spp, were shown to harbour a carbapenemase (IMP-4).

Australian Group on Antimicrobial Resistance (AGAR) Australian Gram-negative Surveillance Outcome Program (GnSOP) Bloodstream Infection Annual Report 2022.

The Australian Group on Antimicrobial Resistance (AGAR) performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric gram-negative pathogens. The 2022 survey was the tenth year to focus on blood stream infections caused by Enterobacterales, and the eighth year where Pseudomonas aeruginosa and Acinetobacter species were included. Fifty-five hospitals Australia-wide participated in 2022. The 2022 survey tested 9,739 isolates, comprising Enterobacterales (8,773; 90.1%), P. aeruginosa (840; 8.6%) and Acinetobacter species (126; 1.3%), using commercial automated methods. The results were analysed using Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints (January 2023). Key resistances included resistance to the third-generation cephalosporin ceftriaxone in 12.7%/12.7% (CLSI/EUCAST criteria) of Escherichia coli and in 6.6%/6.6% of Klebsiella pneumoniae complex. Resistance rates to ciprofloxacin were 13.7%/13.7% for E. coli; 7.8%/7.8% for K. pneumoniae complex; 5.3%/5.3% for Enterobacter cloacae complex; and 4.3%/10.0% for P. aeruginosa. Resistance rates to piperacillin-tazobactam were 2.8%/5.9%; 2.9%/8.7%; 18.3%/27.2%; and 6.1%/14.7% for the same four species, respectively. Twenty-nine Enterobacterales isolates from 28 patients were shown to harbour a carbapenemase gene: 18 blaIMP-4; four blaNDM-5; three blaNDM-1; one blaOXA-181; one blaOXA-244; one blaNDM-1 + blaOXA-181; and one blaNDM-5 + blaOXA-181. Transmissible carbapenemase genes were also detected among two Acinetobacter baumannii complex isolates (blaOXA-23) and one P. aeruginosa (blaNDM-1) in the 2022 survey.

Australian Group on Antimicrobial Resistance (AGAR) Australian Gram-negative Sepsis Outcome Programme (GnSOP) Annual Report 2020.

Abstract: The Australian Group on Antimicrobial Resistance (AGAR) performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric gram-negative pathogens. The 2020 survey was the eighth year to focus on bloodstream infections caused by Enterobacterales, and the sixth year in which Pseudomonas aeruginosa and Acinetobacter species were included. Eight thousand seven hundred and fifty-two isolates, comprising Enterobacterales (7,871, 89.9%), P. aeruginosa (771, 8.8%) and Acinetobacter species (110, 1.3%), were tested using commercial automated methods. The results were analysed using Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints (January 2021). Of the key resistances, resistance to the third-generation cephalosporin ceftriaxone was found in 13.5%/13.5% (CLSI/EUCAST criteria) of Escherichia coli and 8.7%/8.7% of Klebsiella pneumoniae. Resistance rates to ciprofloxacin were 16.1%/16.1% for E. coli; 9.9%/9.9% for K. pneumoniae; 5.8%/5.8% for Enterobacter cloacae complex; and 4.5%/8.1% for P. aeruginosa. Resistance rates to piperacillin-tazobactam were 2.5%/6.6%; 3.9%/12.5%; 16.9%/26.3%; and 5.5%/14.4% for the same four species respectively. Thirty-two isolates from 32 patients were shown to harbour at least one carbapenemase gene: 19 blaIMP-4, three blaGES-5, two blaNDM-1, two blaNDM-5, two blaOXA-48, two blaOXA-181, one blaIMI-1, and one blaOXA-23+NDM-1.

Australian Group on Antimicrobial Resistance (AGAR) Australian Gram-negative Surveillance Outcome Program (GnSOP).

Abstract: The Australian Group on Antimicrobial Resistance (AGAR) performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric gram-negative pathogens. The 2021 survey was the ninth year to focus on bloodstream infections caused by Enterobacterales, and the seventh year where Pseudomonas aeruginosa and Acinetobacter species were included. The 2021 survey tested 8,947 isolates, comprising Enterobacterales (8,104; 90.6%), P. aeruginosa (745; 8.3%) and Acinetobacter species (98; 1.1%), using commercial automated methods. The results were analysed using Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints (January 2022). Of the key resistances, resistance to the third-generation cephalosporin ceftriaxone was found in 12.5%/12.5% (CLSI/EUCAST criteria) of Escherichia coli and in 6.1%/6.1% of Klebsiella pneumoniae. Resistance rates to ciprofloxacin were 12.3%/12.3% for E. coli; 7.2%/7.2% for K. pneumoniae; 5.4%/5.4% for Enterobacter cloacae complex; and 3.7%/8.0% for P. aeruginosa. Resistance rates to piperacillin-tazobactam were 2.8%/6.5%; 2.9%/9.9%; 18.4%/28.1%; and 6.9%/12.8% for the same four species, respectively. Seventeen Enterobacterales isolates from 17 patients were shown to harbour a carbapenemase gene: 12 blaIMP-4; two blaNDM-7; one blaNDM-1; one blaOXA-181; and one blaKPC-2. No transmissible carbapenemase genes were detected among P. aeruginosa or Acinetobacter isolates in the 2021 survey.

Early dissemination of NDM-1- and OXA-181-producing Enterobacteriaceae in Indian hospitals: report from the SENTRY Antimicrobial Surveillance Program, 2006-2007.

Among 39 carbapenem-resistant Enterobacteriaceae (2.7% overall; Escherichia coli, Enterobacter cloacae, and Klebsiella pneumoniae strains) isolated in 2006 and 2007 in India, 15 strains carried bla(NDM-1) and 10 harbored a gene encoding a variant of the carbapenemase OXA-48, named bla(OXA-181). One E. cloacae strain harbored bla(VIM-6), and one K. pneumoniae strain carrying bla(OXA-181) also possessed bla(VIM-5). Multiple pulsed-field gel electrophoresis patterns and clonal dissemination within and among sites were observed. Isolates producing NDM-1 were disseminated in Indian health care facilities as early as 2006.

Worldwide distribution and environmental origin of the Adelaide imipenemase (AIM-1), a potent carbapenemase in Pseudomonas aeruginosa.

Carbapenems are potent broad-spectrum ß-lactam antibiotics reserved for the treatment of serious infections caused by multidrug-resistant bacteria such as Pseudomonas aeruginosa. The surge in P. aeruginosa resistant to carbapenems is an urgent threat, as very few treatment options remain. Resistance to carbapenems is predominantly due to the presence of carbapenemase enzymes. The assessment of 147 P. aeruginosa isolates revealed that 32 isolates were carbapenem non-wild-type. These isolates were screened for carbapenem resistance genes using PCR. One isolate from wastewater contained the Adelaide imipenemase gene (blaAIM-1) and was compared phenotypically with a highly carbapenem-resistant clinical isolate containing the blaAIM-1 gene. A further investigation of wastewater samples from various local healthcare and non-healthcare sources as well as river water, using probe-based qPCR, revealed the presence of the blaAIM-1 gene in all the samples analysed. The widespread occurrence of blaAIM-1 throughout Adelaide hinted at the possibility of more generally extensive spread of this gene than originally thought. A blast search revealed the presence of the blaAIM-1 gene in Asia, North America and Europe. To elucidate the identity of the organism(s) carrying the blaAIM-1 gene, shotgun metagenomic sequencing was conducted on three wastewater samples from different locations. Comparison of these nucleotide sequences with a whole-genome sequence of a P. aeruginosa isolate revealed that, unlike the genetic environment and arrangement in P. aeruginosa, the blaAIM-1 gene was not carried as part of any mobile genetic elements. A phylogenetic tree constructed with the deduced amino acid sequences of AIM-1 suggested that the potential origin of the blaAIM-1 gene in P. aeruginosa might be the non-pathogenic environmental organism, Pseudoxanthomonas mexicana.

Inactivation, removal, and regrowth potential of opportunistic pathogens and antimicrobial resistance genes in recycled water systems.

With two thirds of the global population living in areas affected by water scarcity, wastewater reuse is actively being implemented or explored by many nations. There is a need to better understand the efficacy of recycled water treatment plants (RWTPs) for removal of human opportunistic pathogens and antimicrobial resistant microorganisms. Here, we used a suite of probe-based multiplex and SYBR green real-time PCR assays to monitor enteric opportunistic pathogens (EOPs; Acinetobacter baumannii, Arcobacter butzlieri, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Legionella spp., Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Enteritidis, Streptococcus spp.) and antimicrobial resistance genes (ARGs; qnrS, blaSHV, blaTEM, blaGES, blaKPC, blaIMI, blaSME, blaNDM, blaVIM, blaIMP, blaOXA-48-like, mcr-1 and mcr-3) of key concern from an antimicrobial resistance (AMR), waterborne and foodborne disease perspective. The class 1 integron-integrase gene (intl1) was quantified as a proxy for multi-drug resistance. EOPs, intl1 and ARGs absolute abundance (DNA and RNA) and metabolic activity (RNA) was assessed through three RWTPs with differing treatment trains. Our results indicate that RWTPs produced high quality recycled water for non-potable reuse by removing >95% of EOPs and ARGs, however, subpopulations of EOPs and ARGs survived disinfection and demonstrated potential to become actively growing members of the recycled water and distribution system microbiomes. The persistence of functional intl1 suggests that significant genetic recombination capacity remains in the recycled water, along with the likely presence of multi-drug resistant bacteria. Results provide new insights into the persistence and growth of EOPs, and prevalence and removal of ARGs in recycled water systems. These data will contribute towards the emerging evidence base of AMR risks in recycled water to inform quantitative risk-based policy development regarding water recycling schemes.