The microbiology of infected pancreatic necrosis.

BACKGROUND: Acute pancreatitis (AP) continues to cause significant morbidity and mortality, especially when it leads to infected pancreatic necrosis (IPN). Modern treatment of IPN frequently involves prolonged courses of antibiotics in combination with minimally invasive therapies. This study aimed to update the existing evidence base by identifying the pathogens causing IPN and therefore aid future selection of empirical antibiotics. METHODS: Clinical data, including microbiology results, of consecutive patients with IPN undergoing minimally invasive necrosectomy at our institution between January 2009 and July 2016 were retrospectively reviewed. RESULTS: The results of 40 patients (22 males and 18 females, median age 60 years) with IPN were reviewed. The etiology of AP was gallstones, alcohol, dyslipidemia and unknown in 31, 2, 2 and 5 patients, respectively. The most frequently identified microbes in microbiology cultures were Enterococcus faecalis and faecium (22.5% and 20.0%) and Escherichia coli (20.0%). In 19 cases the cultures grew multiple organisms. The antibiotics with the least resistance amongst the microbiota were teicoplanin (5.0%), linezolid (5.6%), ertapenem (6.5%), and meropenem (7.4%). CONCLUSION: The carbapenem antibiotics, ertapenem and meropenem provide good antimicrobial cover against the common, mainly enteral, microorganisms causing IPN. Culture and sensitivity results of acquired samples should be regularly reviewed to adjust prescribing and monitor for emergence of resistance.

Genotypic analysis of two hypervariable human cytomegalovirus genes.

Most human cytomegalovirus (HCMV) genes are highly conserved in sequence among strains, but some exhibit a substantial degree of variation. Two of these genes are UL146, which encodes a CXC chemokine, and UL139, which is predicted to encode a membrane glycoprotein. The sequences of these genes were determined from a collection of 184 HCMV samples obtained from Africa, Australia, Asia, Europe, and North America. UL146 is hypervariable throughout, whereas variation in UL139 is concentrated in a sequence encoding a potentially highly glycosylated region. The UL146 sequences fell into 14 genotypes, as did all previously reported sequences. The UL139 sequences grouped into 8 genotypes, and all previously reported sequences fell into a subset of these. There were minor differences among continents in genotypic frequencies for UL146 and UL139, but no clear geographical separation, and identical nucleotide sequences were represented among communities distant from each other. The frequent detection of multiple genotypes indicated that mixed infections are common. For both genes, the degree of divergence was sufficient to preclude reliable sequence alignments between genotypes in the most variable regions, and the mode of evolution involved in generating the genotypes could not be discerned. Within genotypes, constraint appears to have been the predominant mode, and positive selection was detected marginally at best. No evidence was found for linkage disequilibrium. The emerging scenario is that the HCMV genotypes developed in early human populations (or even earlier), becoming established via founder or bottleneck effects, and have spread, recombined and mixed worldwide in more recent times.