Neonatal enteral feeding tubes as loci for colonisation by members of the Enterobacteriaceae

Background The objective of this study was to determine whether neonatal nasogastric enteral feeding tubes are colonised by the opportunistic pathogen Cronobacter spp. (Enterobacter sakazakii) and other Enterobacteriaceae, and whether their presence was influenced by the feeding regime. Methods One hundred and twenty-nine tubes were collected from two neonatal intensive care units (NICU). A questionnaire on feeding regime was completed with each sample. Enterobacteriaceae present in the tubes were identified using conventional and molecular methods, and their antibiograms determined. Results The neonates were fed breast milk (16%), fortified breast milk (28%), ready to feed formula (20%), reconstituted powdered infant formula (PIF, 6%), or a mixture of these (21%). Eight percent of tubes were received from neonates who were 'nil by mouth'. Organisms were isolated from 76% of enteral feeding tubes as a biofilm (up to 107 cfu/tube from neonates fed fortified breast milk and reconstituted PIF) and in the residual lumen liquid (up to 107 Enterobacteriaceae cfu/ml, average volume 250 µl). The most common isolates were Enterobacter cancerogenus (41%), Serratia marcescens (36%), E. hormaechei (33%), Escherichia coli (29%), Klebsiella pneumoniae (25%), Raoultella terrigena (10%), and S. liquefaciens (12%). Other organisms isolated included C. sakazakii (2%),Yersinia enterocolitica (1%),Citrobacter freundii (1%), E. vulneris (1%), Pseudomonas fluorescens (1%), and P. luteola (1%). The enteral feeding tubes were in place between < 6 h (22%) to > 48 h (13%). All the S. marcescens isolates from the enteral feeding tubes were resistant to amoxicillin and co-amoxiclav. Of additional importance was that a quarter of E. hormaechei isolates were resistant to the 3rd generation cephalosporins ceftazidime and cefotaxime. During the period of the study, K. pneumoniae and S. marcescens caused infections in the two NICUs. Conclusion This study shows that neonatal enteral feeding tubes, irrespective of feeding regime, act as loci for the bacterial attachment and multiplication of numerous opportunistic pathogens within the Enterobacteriaceae family. Subsequently, these organisms will enter the stomach as a bolus with each feed. Therefore, enteral feeding tubes are an important risk factor to consider with respect to neonatal infections.

Genotypic and antimicrobial characterisation of Propionibacterium acnes isolates from surgically excised lumbar disc herniations

The anaerobic skin commensal Propionibacterium acnes is an underestimated cause of human infections and clinical conditions. Previous studies have suggested a role for the bacterium in lumbar disc herniation and infection. To further investigate this, five biopsy samples were surgically excised from each of 64 patients with lumbar disc herniation. P. acnes and other bacteria were detected by anaerobic culture, followed by biochemical and PCR-based identification. In total, 24/64 (38%) patients had evidence of P. acnes in their excised herniated disc tissue. Using recA and mAb typing methods, 52% of the isolates were type II (50% of culture-positive patients), while type IA strains accounted for 28% of isolates (42% patients). Type III (11% isolates; 21% patients) and type IB strains (9% isolates; 17% patients) were detected less frequently. The MIC values for all isolates were lowest for amoxicillin, ciprofloxacin, erythromycin, rifampicin, tetracycline, and vancomycin (≤1mg/L). The MIC for fusidic acid was 1-2 mg/L. The MIC for trimethoprim and gentamicin was 2 to ≥4 mg/L. The demonstration that type II and III strains, which are not frequently recovered from skin, predominated within our isolate collection (63%) suggests that the role of P. acnes in lumbar disc herniation should not be readily dismissed. © 2013 Jess Rollason et al.

Low level of cross-resistance between triclosan and antibiotics in Escherichia coli K-12 and E. coli O55 compared to E-coli O157

Misuse of biocides has encouraged the emergence of resistance and cross-resistance in certain strains. This study investigated resistance of triclosan-adapted Escherichia coli K-12 and E. coli O55 to antimicrobial agents and compared these to E. coli O157:H7. Cross-resistance in E. coli K-12 and E. coli O55 was observed however to a lesser extent than in E. coli O157:H7. Triclosan-adapted E. coli K-12 demonstrated cross-resistance to chloramphenicol, whereas triclosan-adapted E. coli O55 exhibited resistance to trimethoprim. In comparison, E. coli O157:H7 was resistant to chloramphenicol, tetracycline, amoxicillin, amoxicillin/clavulanic acid, trimethoprim, benzalkonium chloride and chlorohexidine suggesting strain specific rather than general resistance mechanisms. © 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.