INTRODUCTION
Cystic fibrosis (CF) is among the most common recessive genetic
disorders globally and affects South Africans at varying frequencies
depending on
race.1,2 This
disorder occurs at incidences of 1:3 000, 1:10 300 and 1:14 000 in
white, mixed-race and black South African population groups,
respectively.3Pseudomonas aeruginosa (P. aeruginosa ) is recognised as
one of the most significant CF lung pathogens in South Africa and
worldwide.4Persistent lung colonisation of CF patients with P. aeruginosahas been associated with poorer patient outcomes such as accelerated
decline in lung function and higher rates of
mortality.4-6
Cystic fibrosis patients are typically infected or colonised with a
unique strain ofP. aeruginosa . 7However, CF clinics globally have reported multiple instances where CF
patients that have shared environments such as CF clinics, or even
shared geographical locations carried identical shared P.
aeruginosastrains. 5,8These shared P. aeruginosa strains, which have also been referred
to as epidemic or transmissible strains have been reported in some
settings to be more virulent, multidrug resistant (MDR) and associated
with increased mortality
rates.9,10 In
1996, the first epidemic P. aeruginosa strain was identified in
CF patients from Liverpool, England and was termed the Liverpool
Epidemic Strain
(LES).11 Since
then, epidemic strains of P. aeruginosa have been reported in CF
patients from Australia, North America and multiple European
countries.12
Australia is among the countries with the highest number of reported
epidemic P. aeruginosa strains in CF
patients.12,13 The P. aeruginosa Australian
Epidemic Strains (AES) now renamed AUST have been described in CF
patients from Tasmania and
Australia.12,14Pseudomonas aeruginosa AUST-01 (ST649), AUST-02 (ST775) and
AUST-03 (ST242) are among the most common epidemic strains in these
regions.5,12 The P. aeruginosa AUST-03 (also
known as AES-III) epidemic strain was first described in CF patients
from Tasmania in 2003 and has caused outbreaks in Tasmania and
Australia.12,15
The frequent genomic surveillance of CF pathogens in high income
countries has enabled the detection of epidemic strains infecting CF
patients. However, in low to middle income countries (LMICs) such as
South Africa and other African countries where resources are limited,
surveillance of CF pathogens is performed infrequently or not at all.
The identification of CF lung pathogens that are of increased virulence
and are epidemic in nature is of paramount importance for the prevention
of outbreaks. To our knowledge, highly transmissible or epidemic strains
of P. aeruginosa have not been reported in CF patients from South
Africa. Here we report the presence of the Australian/Tasmanian epidemic
strain AUST-03 (ST 242) discovered in two CF patients at a public
academic hospital in Gauteng, South Africa. The aim of this study was to
describe the genomic resistance characteristics of the P.
aeruginosa ST 242 (AUST-03) strains discovered at this hospital during
a previous study and to make phylogenetic comparisons with P.
aeruginosa AUST-03 strains reported in other geographic settings.