taccetti.qxp 7/8/09 4:10 pm Page 54
Cystic Fibrosis
Methicillin-resistant Staphylococcus aureus in Cystic Fibrosis
Giovanni Taccetti,
1
Silvia Campana,
1
Priscilla Cocchi,
1
Anna Silvia Neri,
1
Francesca Trevisan,
1
Vanessa Boni,
1
Cesare Braggion
1
and Filippo Festini
2
1. Cystic Fibrosis Centre, Meyer Hospital, Florence; 2. Department of Paediatrics, University of Florence
Abstract
Cystic fibrosis (CF) is the most common inherited disease in the Caucasian population. The importance of non-fermentative Gram-negative
species is well known, but an additional matter of concern for CF patients is the emergence of methicillin-resistant Staphylococcus aureus
(MRSA). It is not clear whether the increase in MRSA prevalence in CF patients is due to community-associated (CA) MRSA or hospital-
associated (HA) MRSA strains. Because CF patients undergo frequent hospitalisation, they have generally been assumed to be at risk of
acquiring HA-MRSA, but recent molecular studies have shown instead a prevalence of CA-MRSA as causative organisms. The potential
negative effect of MRSA on pulmonary function has been demonstrated in ample numbers of patients, but further studies are needed to
verify possible diverse pathogenic effects of MRSA on the lung in relation to different molecular characteristics of MRSA strains. As for other
pathogens, eradicating MRSA from the airways of patients affected by CF can theoretically benefit the patient and reduce the possibility
of diffusion of this bacteria. CF patients who are experiencing acute pulmonary exacerbations require parenteral antibiotic treatment, and
vancomycin is considered the first-choice drug. Unlike Pseudonomas aeruginosa chronic infection, the utility of chronic suppressive
antibiotic treatment has not yet been studied in CF patients who chronically harbour MRSA in their airways. Hand hygiene is an important
component of standard precautions, and many studies demonstrate a temporal relationship between improved adherence to
recommended hand hygiene practices and control of multidrug-resistant organism transmission.
Keywords
Cystic fibrosis, methicillin-resistant Staphylococcus aureus, antibiotic treatment
Disclosure: This work was supported by the Italian Cystic Fibrosis Research Foundation (grant FFC #11/2007) with the contribution of the Riggi family. The authors have no
conflicts of interest to declare.
Received: 3 November 2008 Accepted: 14 May 2009
g.taccetti@meyer.it
Cystic fibrosis (CF) is the most common inherited disease in the defines a case of MRSA infection as community-acquired when it is
Caucasian population and results from a defective chloride channel, the diagnosed in outpatients or within 48 hours of hospitalisation if the
cystic fibrosis transmembrane regulator (CFTR).
1
CF patients’ lungs patient lacks the traditional risk factors for MRSA.
6,7
The CDC defines
become an ideal habitat for several bacterial species. Staphylococcus hospital-acquired MRSA infections as those in patients who have had
aureus is usually the first pathogen to colonise the airways of CF frequent or recent contact with hospitals or healthcare facilities
patients, and in the pre-antibiotic era this pathogen was the major cause within the previous year or who have recently undergone an invasive
of morbidity and mortality.
2,3
Recently, the importance of non- medical procedure.
15
The term ‘healthcare-acquired MRSA’ is
fermentative Gram-negative species has been noted, but an additional preferable because it includes the possibility of acquiring an infection
matter of concern for CF patients is represented by the emergence of in an extrahospital environment, in relation to the evolution of the
methicillin-resistant S. aureus (MRSA).
4–10
Since the first isolation of MRSA organisation of care for CF patients.
8
The terms ‘associated’ or
in the 1960s, this pathogen has become an important cause of infection ‘acquired’ are often used interchangeably.
5,6
Recently, it was
and one of the most prevalent causes of nosocomial infections.
5–8
Its role suggested that the term ‘associated’ be used to describe strains
in CF has not been well understood to date. There is little evidence isolated either in the community or in healthcare environments in a
available about its prevalence, antibiotic resistance pattern, context in which the strain acquired is not precisely identified.
epidemiology, transmissibility, virulence and clinical impact on CF Instead, the term ‘acquired’ is to be used to describe the location of
patients.
9–14
An improvement in our knowledge of this important MRSA exposure that led to colonisation or infection.
8
emerging pathogen could be vital to the management of pulmonary
infections in CF patients. This article focuses on the epidemiology, MRSA can be resistant either just to methicillin and other β-lactam
microbiology, clinical significance and treatment of MRSA in CF patients. antibiotics or also to other classes of antibiotics such as tetracyclines,
trimethoprim–sulfamethoxazole, rifampin, clindamycin, quinolones
Nomenclature and macrolides or even to multiple classes of antibiotics.
5
In this latter
The terminology used for cases of colonisation or infection due to case, it should be called multidrug-resistant MRSA.
8
Most hospital-
MRSA is varied. The Centers for Disease Control and Prevention (CDC) associated strains are resistant to several classes of antibiotics,
54 © TOUCH BRIEFINGS 2009
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