Transmission of colistin‐resistant Pseudomonas aeruginosa between patients attending a pediatric cystic fibrosis center

Abstract

We report on an outbreak of colistin-resistant Pseudomonas aeruginosa (CRPA) that occurred in a United Kingdom pediatric cystic fibrosis (CF) unit and involved six children over a period of 5 years. All CRPA-positive children had received aerosolized colistin therapy before first isolation of resistant organisms (mean duration, 3.1 years). Four of the 6 had also received courses of intravenous colistin in the year before the first isolation of CRPA. No impact of CRPA acquisition on respiratory function, clinical condition, or radiological parameters could be demonstrated. Four of the 6 children carried isolates of CRPA indistinguishable on genotyping. Two of these 4 children were sisters. The other 2 were on the same ward together at time of first isolation, and subsequently shared overlapping admissions with one of the sisters. While there is no conclusive evidence for the route of transmission, the frequency of overlapping in-patient admissions between 3 of these patients is suggestive of patient-to-patient transfer in the nosocomial setting.CF clinicians should be aware that colistin resistance can occur in P. aeruginosa, and some of these strains are capable of spread within CF units.

Cystic fibrosis patients and families support cross-infection measures

“…Combined with intensive antibiotic therapy, this has led to significant reductions in incidence of chronic PA infection [8]. Similar segregation practices have been adopted elsewhere based on evidence from genomic fingerprinting that some PA strains are transmissible [9,10]. By contrast, such evidence was not found in Vancouver, Canada, and, hence, segregation measures are not recommended [11].…”

“…The positive aspects have been discussed previously, but there are some important negative aspects which deserve mention. These include: the generation of a fearful attitude about becoming colonised with PA; feelings of alienation within the colonised group; socialisation limitations; and difficulties explaining to young children why they should not play with others during lengthy hospital stays [9]. Unfortunately, cohorting has caused a decline in large group education sessions, CF camps and other social gatherings, which are particularly important in empowerment of the CF child and adolescent.…”

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

“…49,50 Nonetheless, antimicrobial susceptibility can distinguish methicillin-susceptible S. aureus (MSSA) from MRSA, identify unique multidrug-resistance patterns, and has been crucial for epidemiologic investigations. For example, CF clinicians were alerted to the transmission of epidemic strains of P. aeruginosa due to the emergence of ceftazidime-resistant, 51 colistin-resistant, 52 or multidrug-resistant strains. 30,53 Thus, susceptibility testing is still recommended as per the 2003 Infection Control Guideline for CF.…”

Subinhibitory concentrations of the cationic antimicrobial peptide colistin induce the pseudomonas quinolone signal in Pseudomonas aeruginosa

“…P. aeruginosa has developed 'adaptive tolerance' to colistin, mediated through the PhoPQ and PmrAB two-component systems that control aminoarabinose modification of the LPS (McPhee et al, 2003). Pseudomonas strains isolated from patients treated with colistin have aminoarabinose-modi-fied lipid A, providing evidence that P. aeruginosa can adapt to the presence of colistin in the airways of the CF lung (Denton et al, 2002;Frederiksen et al, 1999).…”

“…This creates an underlying risk of sublethal treatment and the potential development of resistance. Indeed, the first reports of colistin-tolerant clinical isolates have already been published (Denton et al, 2002). P. aeruginosa has developed 'adaptive tolerance' to colistin, mediated through the PhoPQ and PmrAB two-component systems that control aminoarabinose modification of the LPS (McPhee et al, 2003).…”