Variation in erythromycin and clindamycin resistance patterns between New Zealand and Australian group B streptococcus isolates.

BACKGROUND: Intrapartum chemoprophylaxis for group B streptococcus (GBS) carriers reduces the risk of early-onset neonatal GBS infection. For women with ß-lactam allergy, either erythromycin or clindamycin are administered. Recent reports worldwide suggest that GBS resistance to these antibiotics is increasing. AIMS: To compare erythromycin and clindamycin resistance phenotypes in invasive neonatal GBS isolates across New Zealand and Australia over the past two decades and to determine whether regional variation in resistance patterns exist. METHOD: Invasive neonatal GBS isolates were collected from laboratories across New Zealand (n=107) and Australia (n=74) over two time periods (1992-1994 and 2002-2004 in New Zealand; 1982-2001 and 2002-2006 in Australia) and subjected to standard antibiotic susceptibility testing. A nested sub-study in New Zealand examined antibiotic susceptibilities of 112 maternal colonising GBS isolates during 2003-2004. RESULTS: Erythromycin resistance among invasive neonatal GBS isolates increased across both countries over the past decade, with similar rates of resistance in New Zealand (9%) and Australia (6%) in recent years. New Zealand erythromycin-resistant GBS isolates commonly displayed cross-resistance to clindamycin. Also, there were significantly higher rates of isolated clindamycin resistance in GBS isolates from New Zealand than Australia (P=0.034). Maternal GBS isolates from New Zealand showed similar resistance patterns to neonatal isolates. CONCLUSION: Erythromycin and clindamycin resistance among invasive neonatal GBS isolates has emerged in both New Zealand and Australia over the past decade and is consistent with global trends in GBS resistance patterns. Although regional variations exist, these findings should be considered when implementing intrapartum GBS prevention strategies.

Prevalence and types of extended-spectrum beta-lactamases among urinary Escherichia coli and Klebsiella spp. in New Zealand.

The aims of this survey were (i) to determine the prevalence of extended-spectrum beta-lactamases (ESBLs) among urinary Escherichia coli and Klebsiella spp. in New Zealand (NZ), (ii) to identify the relative prevalence of ESBL types and (iii) to investigate clonality among ESBL-producing E. coli and Klebsiella spp. During a 4-week period in 2006, 86% of NZ hospital and community diagnostic microbiology laboratories participated in the survey and referred isolates to the national reference laboratory. A total of 86 ESBL-producing isolates were identified, comprising 55 E. coli and 31 Klebsiella spp. (all Klebsiella pneumoniae), equating to prevalence rates of 0.7% and 4.2%, respectively. The majority of the ESBL-producing E. coli (80.0%) and K. pneumoniae (58.6%) were reported to be from community-acquired urinary tract infections. CTX-M-15 and CTX-M-14 accounted for 75.9% and 13.3%, respectively, of the ESBL types identified. A novel ESBL, designated CTX-M-68, was identified. Most CTX-M-15-producing isolates were multiresistant to three or more antibiotic classes. Pulsed-field gel electrophoresis typing identified a wide diversity of strains among the ESBL-producing E. coli, whereas the K. pneumoniae were more clonal. The results of this survey show that the prevalence of ESBLs has increased in recent years in NZ, that CTX-M ESBLs are almost wholly dominant and that ESBL-producing organisms are already established as community-acquired pathogens.