Aura 2016: first Australian report on antimicrobial use and resistance in human health

4.14 Streptococcus pyogenes

Health impact

S. pyogenes, also called group A Streptococcus, is an important human pathogen. It most commonly causes skin and soft tissue infections, and acute pharyngitis, but can cause serious and life-threating infections such as scarlet fever, septicaemia, bone and joint infections, toxic shock syndrome, necrotising fasciitis and pneumonia. This organism is also associated with two ‘poststreptococcal’ syndromes: acute glomerulonephritis and rheumatic fever. These syndromes are now rare in most parts of Australia, but are still seen frequently in remote Aboriginal and Torres Strait Islander communities, contributing to substantial long-term morbidity in these populations.

Treatment

Benzylpenicillin remains the treatment of choice for S. pyogenes infections. In patients who are allergic to penicillins, macrolides such as erythromycin and first-generation cephalosporins are treatment options. Although antimicrobial treatment is usually administered as part of the treatment for poststreptococcal syndromes, other non-antimicrobial treatments are the mainstay of management. Patients who have experienced one episode of acute rheumatic fever are prone to further episodes and worsening organ damage; as a consequence, they are administered long-term prophylaxis (usually over decades) with benzathine penicillin (intramuscularly) or phenoxymethylpenicillin (orally).

Types and impact of resistance

Confirmed resistance to benzylpenicillin has never been reported anywhere in the world in this species, but the consequences of its emergence would be substantial. It is expected that, based on observations of other members of the Streptococcus genus, resistance to benzylpenicillin would also affect susceptibility to first-generation cephalosporins. In contrast, acquired resistance to macrolide antimicrobials has been present in S. pyogenes for many years, with levels of resistance seeming to fluctuate in line with changes in circulating clones. First-generation cephalosporins are treatment options for penicillin-allergic patients who are infected with macrolide-resistant strains.

Key findings (Queensland)

Resistance to key antimicrobial agents is low, apart from tetracyclines, which are rarely used for treatment (Figure 4.40). Resistance to erythromycin (and therefore other macrolides) is low. There was some variation in macrolide resistance rates among clinical settings (Figure 4.41).

Resistance to key antimicrobial agents in S. pyogenes is low, apart from tetracyclines, which are rarely used for treatment.

Figure 4.40 Streptococcus pyogenes resistance to individual agents, 2014

ERY = erythromycin; PEN = benzylpenicillin; SXT = trimethoprim–sulfamethoxazole; TET = tetracycline

Sources: OrgTRx (Queensland); Sullivan Nicolaides Pathology (Queensland and northern New South Wales)

Figure 4.41 Streptococcus pyogenes resistance, by clinical setting, 2014

ERY = erythromycin; na = not available (either not tested or tested against an inadequate number of isolates); PEN = benzylpenicillin; SXT = trimethoprim–sulfamethoxazole; TET = tetracycline

Sources: OrgTRx (public hospitals and health services); Sullivan Nicolaides Pathology (private hospitals and community)

Data table: Figure 4.41

Agent	Public hospitals and health services (n = 5,155), % resistant	Private hospitals (n = 102), % resistant	Community (n = 4,689), % resistant
PEN	0.0	0.0	0.0
ERY	2.3	7.0	4.4
TET	na	14.9	na
SXT	na	4.1	1.1

Chapter 5 International comparisons

Key messages

Antimicrobial use (AU) in the Australian community is higher than in many other countries.

AU in Australian hospitals can appear high or low in comparison with other countries, depending on the measure used. These differences may reflect different healthcare practices (for example, hospital care versus community care) in different countries.

Rates of antimicrobial resistance (AMR) in gram-negative organisms (Escherichia coli and Klebsiella pneumoniae) in Australia are lower than in other countries, but rates of AMR in gram-positive organisms (Staphylococcus aureus and Enterococcus faecium) are high to very high.

Australia has low rates of resistance to fluoroquinolones compared with other countries, reflecting the restricted use of this antimicrobial class in Australia.

Many countries, particularly in Europe, have established systems for reporting country-wide data on AU and AMR. This first national report on AU and AMR in Australia allows us to make comparisons between Australia and other countries. Such comparisons provide a benchmark that can help to inform practices in Australia.