Distribution of Serotypes, Genotypes, and Resistance Determinants among Macrolide-Resistant Streptococcus pneumoniae Isolates

ABSTRACT Macrolide resistance in Streptococcus pneumoniae has emerged as an important clinical problem worldwide over the past decade. The aim of this study was to analyze the phenotypes (serotype and antibiotic susceptibility), genotypes (multilocus sequence type [MLST] and antibiotic resistance gene/transposon profiles) among the 31% (102/328) of invasive isolates from children in New South Wales, Australia, in 2005 that were resistant to erythromycin. Three serotypes—19F (47 isolates [46%]), 14 (27 isolates [26%]), and 6B (12 isolates [12%])—accounted for 86 (84%) of these 102 isolates. Seventy four (73%) isolates had the macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype and carried Tn916 transposons (most commonly Tn6002); of these, 73 (99%) contained the erythromycin ribosomal methylase gene [erm(B)], 34 (47%) also carried the macrolide efflux gene [mef(E)], and 41 (55%) belonged to serotype 19F. Of 28 (27%) isolates with the M phenotype, 22 (79%) carried mef(A), including 16 (57%) belonging to serotype 14, and only six (19%) carried Tn916 transposons. Most (84%) isolates which contained mef also contained one of the msr(A) homologues, mel or msr(D); 38 of 40 (95%) isolates with mef(E) (on mega) carried mel, and of 28 (39%) isolates with mef(A), 10 (39%) carried mel and another 11(39%) carried msr(D), on Tn1207.1. Two predominant macrolide-resistant S. pneumoniae clonal clusters (CCs) were identified in this population. CC-271 contained 44% of isolates, most of which belonged to serotype 19F, had the MLSB phenotype, were multidrug resistant, and carried transposons of the Tn916 family; CC-15 contained 23% of isolates, most of which were serotype 14, had the M phenotype, and carried mef(A) on Tn1207.1. Erythromycin resistance among S. pneumoniae isolates in New South Wales is mainly due to the dissemination of multidrug-resistant S. pneumoniae strains or horizontal spread of the Tn916 family of transposons.

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Multidrug-Resistant Salmonellaenterica 4,[5],12:i:- Sequence Type 34, New South Wales, Australia, 2016–2017

Emerging Infectious Diseases ◽

10.3201/eid2404.171619 ◽

2018 ◽

Vol 24 (4) ◽

pp. 751-753 ◽

Cited By ~ 24

Author(s):

Alicia Arnott ◽

Qinning Wang ◽

Nathan Bachmann ◽

Rosemarie Sadsad ◽

Chayanika Biswas ◽

...

Keyword(s):

New South ◽

New South Wales ◽

Multidrug Resistant ◽

Sequence Type ◽

South Wales

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Laboratory surveillance of invasive pneumococcal disease in New South Wales, Australia, before and after introduction of 7-valent conjugate vaccine: reduced disease, but not antibiotic resistance rates

Epidemiology and Infection ◽

10.1017/s095026881200218x ◽

2012 ◽

Vol 141 (9) ◽

pp. 1797-1806 ◽

Cited By ~ 6

Author(s):

S. OFTADEH ◽

H. F. GIDDING ◽

G. L. GILBERT

Keyword(s):

Conjugate Vaccine ◽

Invasive Pneumococcal Disease ◽

Pneumococcal Disease ◽

New South ◽

New South Wales ◽

Annual Number ◽

Age Group ◽

Erythromycin Resistance ◽

South Wales ◽

Laboratory Surveillance

SUMMARYWe compared serotype distributions ofStreptococcus pneumoniaeisolates from patients aged <5 and ⩾5 years with invasive pneumococcal disease in New South Wales, Australia, and antibiotic susceptibilities of isolates from the <5 years age group only, before (2002–2004) and after (2005–2009) introduction of the 7-valent pneumococcal conjugate vaccine (PCV7). Overall, there were significant decreases in the mean annual number of referred isolates (770vs. 515) and the proportion belonging to PCV7 serotypes (74%vs. 38%), but non-PCV7 serotypes, particularly 19A, increased (5%vs. 18%). All changes were more marked in the <5 years age group. Susceptibility testing of isolates from the <5 years age group showed variation in resistance between serotypes, but significant overall increases in penicillin non-susceptibility (23%vs. 31%), ceftriaxone resistance (2%vs. 12%) and multidrug resistance (4%vs. 7%) rates; erythromycin resistance fell (32%vs. 25%). Continued surveillance is needed to monitor changes following the introduction of 13-valent PCV in 2012.

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