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Mycobacterium abscessus (MABS) infection represents significant management challenge in cystic fibrosis (CF) patients. This retrospective study (2005-2016) aims to determine the prevalence of the subspecies of MABS isolated from CF patients, to evaluate the persistence over the years of a single subspecies of MABS and to correlate mutations responsible for macrolides and amikacin resistance with MIC values. We investigated 314 strains (1 isolate/patient/year) isolated from the lower respiratory tract of 51 chronically infected CF patients. Sequencing of rpoB gene was performed to identify the MABS subspecies. The erm(41) gene was sequenced to differentiate the strains with and without inducible macrolide resistance. Regions of 23S and 16S rRNA were sequenced to investigate mutations responsible for constitutive resistance to macrolides and aminoglycosides, respectively. Antibiotic susceptibility, using commercial microdilution plates, was evaluated according to CLSI. M. abscessus subsp. abscessus accounted for 64% of the isolates, bolletii subspecies for 16% and massiliense subspecies for 20%. All the massiliense strains presented truncated erm(41) gene while 12 abscessus strains presented the mutation T28->C in the erm(41) gene, which makes it inactive. The 23S rRNA analysis did not show constitutive resistance to macrolides in any strain. Mutation of the 16S rRNA gene was highlighted in 2 strains out of 314, in agreement with high MIC values. The correct identification at the subspecies level and the molecular analysis of 23S rRNA, 16S rRNA and erm gene is useful to guide the treatment strategy in patients with M. abscessus lung infection.

Bacteria from the Burkholderia cepacia complex (Bcc) are capable of causing severe infections in patients with cystic fibrosis (CF). Bcc infection is often extremely difficult to treat due to its intrinsic resistance to multiple antibiotics. In addition, it seems to speed up the decline of lung function and is considered a contraindication for lung transplantation in CF. This study investigates the species of the Bcc strains recovered from chronically infected CF subjects by means of: isolation, identification methods and complete recA nucleotide sequences of 151 samples. Molecular typing showed that B. cenocepacia III is the dominant strain found in the group of subjects being treated at the Milan CF Centre (Italy) and that the infection is chronically maintained by the same species. Defining species by means of molecular analysis yields important information for the clinician in order to establish the most appropriate therapy and implement correct measures for prevention of transmission among CF subjects.

Background: The type of feeding can differently influence bile acid ontogeny during the period of physiologic cholestasis that characterizes early human development., Aim: To investigate the effects of feeding from birth, conventional or partially protein hydrolyzed cow's milk formulas were compared with breast milk regarding bile acid concentration and the composition of gallbladder bile in newborn guinea pigs., Methods: Forty newborn guinea pigs were allocated to one of three different feeding regimens: breast milk (n = 14), intact protein formula (n = 13) and partially protein hydrolyzed formula (n = 13). After 8 days, one third of the pups from each group was sacrificed; another third was sacrificed on the 14th day and the remainder on the 20th day of life. Bile acids in gallbladder bile were analyzed by gas chromatography/mass spectrometry and HPLC., Results: During the first 2 weeks of life, weight gain was significantly higher in breast-fed than in artificially fed pups. An age-related increase in total biliary bile acid concentrations was evident for breast-fed and hydrolyzed formula-fed animals, but not for those fed intact protein formula. Breast-fed animals had the highest total biliary bile acid concentrations on day 20 of life, with significant increases in chenodeoxycholic and 7-oxo-lithocholic acid concentrations, which were absent in the other two groups. Concentrations of 7-oxo-lithocholic acid on day 8 were significantly higher in animals fed intact protein formula compared with breast-fed and partially protein hydrolyzed formula-fed animals., Conclusions: In newborn guinea pigs, breast feeding is associated with a marked increase in biliary bile acid concentrations, which was not observed in artificially fed animals. The higher biliary bile acid concentrations and better weight gain in our breast-fed animals may reflect a greater feed efficiency associated with natural feeding. Biliary bile acid composition on day 8 suggests more rapid intestinal bacterial bile acid biotransformation in animals fed intact protein formula compared to other feeding regimens., (Copyright 2003 S. Karger AG, Basel)