Species distribution and susceptibility of Nocardia isolates in New Zealand 2002-2021.

The aim was to record the distribution and susceptibility of Nocardia species in New Zealand. Local and referred isolates were identified by an evolving approach over the study period including conventional phenotypic methods, susceptibility profiles, matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF) and molecular sequencing. Isolates previously identified as a Nocardia sp. or part of the N. asteroides complex were reidentified by MALDI-TOF and/or molecular methods. Antimicrobial susceptibility to eight antibiotics was performed by standard microbroth dilution. The site of isolation, susceptibility profiles and species distribution were analysed. A total of 383 isolates were tested: N. brasiliensis 23 (6%), N. cyriacigeorgica 42 (11%), N. farcinica 41 (11%), N. nova complex 226 (59%), and 51 (13%) other species/complexes. The respiratory tract was the most common site of infection (244, 64%), with skin and soft tissue the second most common site (104, 27%). All 23 N. brasiliensis isolates were from skin and soft tissue specimens. Almost all isolates (≥98%) were susceptible to amikacin, linezolid and trimethoprim-sulfamethoxazole; 35% and 77% were resistant to clarithromycin and quinolones, respectively. The expected susceptibility profiles of the four common species and complex were observed for most agent-organism parings. Multi-drug resistance was uncommon (3.4%). The spectrum of Nocardia species in New Zealand is similar to overseas reports and our most common group is the N. nova complex. While amikacin, linezolid and trimethoprim-sulfamethoxazole remain good empiric treatment choices, other agents should have their activity confirmed before use.

The emergence of azole resistance in Aspergillus fumigatus complex in New Zealand.

BACKGROUND: Azole resistance in Aspergillus fumigatus (A. fumigatus) is increasing globally. A pan-azole-resistant isolate prompted genetic analysis of local azole-resistant isolates to determine resistance genotypes. METHODS: All A. fumigatus complex isolates were tested by the broth colorimetric micro-dilution method, Sensititre® YeastOne® (SYO) (TREK Diagnostic Systems, West Sussex, England). Epidemiological cutoff values derived from the Clinical & Laboratory Standards Institute method were used to determine the proportion of non-wild-type (non-WT) isolates (ie, those with an increased likelihood to harbour acquired mechanisms of resistance). Non-WT isolates were identified by ß-tubulin gene sequencing and the genotype for azole resistance was determined. The history of the patient with the first pan-resistant isolate was reviewed along with the treatment history of patients with azole-resistant strains. RESULTS: From January 2001 to August 2020, antifungal susceptibility testing was performed on 260 A. fumigatus complex isolates: six isolates were non-WT for one or more azole agent, two A. fumigatus sensu stricto and four other members within the species complex: two A. fischeri and two A. lentulus. There were three non-WT isolates for amphotericin B, three for itraconazole, five for posaconazole and five for voriconazole. All six non-WT strains were isolated in the past nine years (P<0.01), and four in the past three years. Azole-resistance genotyping for the A. fumigatus sensu stricto isolates detected amino acid changes at hot spots in the cyp51A gene: one at G54E and one at G138C. All six isolates were WT for caspofungin. Five of the six patients with azole-resistant strains had previous azole treatment, and the patient with the pan-azole-resistant strain had been on continuous azole treatment for 42 months preceding strain isolation. CONCLUSIONS: New Zealand can be added to the growing list of countries with azole-resistant A. fumigatus complex isolates, including pan-azole resistance in A. fumigatus sensu stricto. While uncommon and mostly found in cryptic species within the complex, azole resistance is increasing. The results provide a baseline for monitoring this emerging antifungal resistance trend in A. fumigatus in New Zealand.

Antifungal susceptibility of clinical mould isolates in New Zealand, 2001-2019.

The objective of this study was to review the antifungal susceptibility of clinical mould isolates performed by the New Zealand Mycology Reference Laboratory. Isolates were either local or referred for testing from other New Zealand laboratories. All isolates were tested by the broth colorimetric microdilution method, Sensititre YeastOne (SYO). Epidemiological cut-off values (ECVs) derived from either the Clinical and Laboratory Standards Institute (CLSI) method or SYO were used to determine the proportion of non-wild type (non-WT) isolates, i.e., those with an increased likelihood to harbour acquired mechanisms of resistance. A total of 614 isolates were tested. Most isolates (55%) were from the respiratory tract followed by musculoskeletal tissue (17%), eye (10%) and abdomen (5%). The azoles had similar activity except for voriconazole which was less active against the Mucorales. The echinocandins had good activity against Aspergillus spp., other hyaline moulds and dematiaceous isolates but were inactive against Fusarium spp., Lomentospora prolificans and the Mucorales. Amphotericin B had best activity against the Mucorales. The two least susceptible groups were Fusarium spp. and L. prolificans isolates. Three Aspergillus isolates were non-WT for amphotericin B, and four non-WT for azoles. Non-WT were not encountered for caspofungin. Non-Aspergillus isolates in New Zealand have susceptibility patterns similar to those reported elsewhere. In contrast to a growing number of other countries, azole resistance was rare in A. fumigatus sensu stricto. Non-WT isolates were uncommon. The results provide a baseline for monitoring emerging antifungal resistance in New Zealand and support current Australasian treatment guidelines for invasive fungal infections.

Antifungal susceptibility testing results of New Zealand yeast isolates, 2001-2015: Impact of recent CLSI breakpoints and epidemiological cut-off values for Candida and other yeast species.

OBJECTIVES: We reviewed the antifungal susceptibility testing results of local yeast isolates (2001-2015) to record the impact of recently updated interpretive criteria and epidemiological cut-off values (ECVs) for yeast species. METHODS: Susceptibility testing was performed using Sensititre® YeastOne®. The results were interpreted following CLSI criteria or YeastOne-derived ECVs. RESULTS: A total of 2345 isolates were tested; 62.0% were from sterile body sites or tissue. Application of new CLSI interpretative criteria for fluconazole increased the proportion of non-susceptible isolates of Candida parapsilosis, Candida tropicalis and Candida glabrata (P≤0.03 for all species). For voriconazole, the greatest increase was for C. tropicalis (P<0.0001). Application of new CLSI interpretive criteria for caspofungin increased the proportion of non-susceptible isolates for C. glabrata and Pichia kudriavzevii (P<0.0001 for both). The new amphotericin ECV (≤2mg/L) did not reveal any non-wild-type (non-WT) isolates in the five species covered. YeastOne itraconazole ECVs detected 2%, 5% and 6% non-WT isolates for P. kudriavzevii, C. tropicalis and C. glabrata, respectively. No itraconazole non-WT isolates of Clavispora lusitaniae were detected. CONCLUSIONS: Whilst most results are similar to other large surveys of fungal susceptibility, the new CLSI interpretive criteria significantly altered the proportion of non-susceptible isolates to fluconazole, voriconazole and caspofungin for several Candida spp. Application of CLSI and YeastOne-derived ECVs revealed the presence of a low proportion of non-WT isolates for many species. The results serve as a baseline to monitor the susceptibility of Candida and other yeast species in New Zealand over time.