Comparison of identification and antimicrobial resistance pattern of Staphylococcus aureus isolated from Amassoma, Bayelsa state, Nigeria.

Background: Staphylococcus aureus is often responsible for fatal infections and recent upsurge of resistant strains has resulted in therapeutic failure. The identification of this microorganism is a major challenge to medical microbiologists in developing countries.Methods: One hundred and eighty five isolates which had been previously isolated from the nares of 185 healthy college students’ volunteers in Amassoma, Bayelsa State, South Nigeria were identified by MALDI TOF mass spectrometry, and PCR amplification of the spa gene. The identified isolates were compared with presumptive identities obtained by growth on MSA, tube coagulation and slide agglutination tests. Antimicrobial susceptibility testing of S. aureus isolates was performed by Kirby Bauer technique while MRSA was screened for by growth on chromIDTM MRSA plate and confirmed by PCR-amplification of mecA/mecC genes.Results: From the 185 staphylococci that grew with yellow colonies on MSA, 24 were positive in the slide coagulase test, while 17 were positive in the tube coagulase test; MALDI TOF mass spectrometry and PCR amplification of the spa gene showed excellent concordance with the tube test, as all tube coagulase-positive strains were identified as S. aureus, while tube coagulase-test negative isolates in all cases were designated as other staphylococcal species by MALDI-TOF mass spectrometry and were spa PCR test negative. All S. aureus isolates were susceptible to clindamycin, vancomycin, fusidic acid, rifampicin and linezolid, while observed resistance to penicillin and trimethoprim were high. Only one MRSA strain was detectedConclusion: The study confirms that the tube coagulase test is an accurate diagnostic method for identification of S. aureus, while growths on MSA and slide agglutination tests are inaccurate. We found a low prevalence of MRSA and a high rate of trimethroprim-resistance in the studied population.Keywords: Antibiotics, coagulase, identification, S. aureus

Achromobacter Species Isolated from Cystic Fibrosis Patients Reveal Distinctly Different Biofilm Morphotypes

Achromobacter species have attracted attention as emerging pathogens in cystic fibrosis. The clinical significance of Achromobacter infection is not yet fully elucidated; however, their intrinsic resistance to antimicrobials and ability to form biofilms renders them capable of establishing long-term chronic infections. Still, many aspects of Achromobacter biofilm formation remain uncharacterized. In this study, we characterized biofilm formation in clinical isolates of Achromobacter and investigated the effect of challenging the biofilm with antimicrobials and/or enzymes targeting the extracellular matrix. In vitro biofilm growth and subsequent visualization by confocal microscopy revealed distinctly different biofilm morphotypes: a surface-attached biofilm morphotype of small aggregates and an unattached biofilm morphotype of large suspended aggregates. Aggregates consistent with our in vitro findings were visualized in sputum samples from cystic fibrosis patients using an Achromobacter specific peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) probe, confirming the presence of Achromobacter biofilms in the CF lung. High antibiotic tolerance was associated with the biofilm phenotype, and biocidal antibiotic concentrations were up to 1000 fold higher than for planktonic cultures. Treatment with DNase or subtilisin partially dispersed the biofilm and reduced the tolerance to specific antimicrobials, paving the way for further research into using dispersal mechanisms to improve treatment strategies

Intravenous antibiotics given for 2 weeks do not eradicate persistent Staphylococcus aureus clones in cystic fibrosis patients

AbstractStaphylococcus aureus is the most commonly isolated pathogen in respiratory tract secretions from young patients with cystic fibrosis (CF), and several treatment strategies are used to control the infection. However, it is not known whether intensified treatment with antimicrobial agents causes eradication of S. aureus clones. We retrospectively determined the impact of intravenous (IV) antimicrobial agents on the suppression and eradication of S. aureus clones. One thousand and sixty-one S. aureus isolates cultured from 2526 samples from 130 CF patients during a 2-year study period were subjected to spa typing. Intervals between positive samples and the occurrence of clone replacements were calculated in relation to courses of IV antimicrobial agents. Of 65 patients chronically infected with S. aureus, 37 received 139 courses of IV antimicrobial agents with activity against S. aureus (mean duration, 15 days; range, 6–31 days). Administration of IV antibiotics increased the time to the next sample with growth of S. aureus: the mean interval between two positive samples was 68 days if IV treatment had been administered, in contrast to 49 days if no IV treatment had been administered (p 0.003). When S. aureus recurred in sputum after IV treatment, the isolate belonged to a different clone in 33 of 114 (29%) intervals, in comparison with 68 of 232 (29%) intervals where IV treatment had not been prescribed (OR 0.98, 95% CI 0.60–1.61). In conclusion, we show that 2 weeks of IV antimicrobial treatment can significantly suppress chronic staphylococcal infection in CF, but is not associated with the eradication of persistent bacterial clones

Incidence of HACEK bacteraemia in Denmark:A 6-year population-based study

Objectives: Bacteria with common microbiological and clinical characteristics are often recognized as a particular group. The acronym HACEK stands for five fastidious genera associated with infective endocarditis (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella). Data on the epidemiology of HACEK are sparse. This article reports a 6-year nationwide study of HACEK bacteraemia in Denmark. Methods: Cases of HACEK bacteraemia occurring during the years 2010–2015 were retrieved from the national Danish microbiology database, covering an average surveillance population of 5.6 million per year. Results: A total of 147 cases of HACEK bacteraemia were identified, corresponding to an annual incidence of 0.44 per 100 000 population. The annual incidence for males was 0.56 per 100 000 and for females was 0.31 per 100 000. The median age was 56 years (range 0–97 years), with variation among the genera. One hundred and forty-three isolates were identified to the species level and six to the genus level: Haemophilus spp, n = 55; Aggregatibacter spp, n = 37; Cardiobacterium spp, n = 9; Eikenella corrodens n = 21; and Kingella spp, n = 27. Conclusions: This is the first study on the incidence of HACEK bacteraemia in a large surveillance population and may inspire further studies on the HACEK group. Haemophilus spp other than Haemophilus influenzae accounted for most cases of HACEK bacteraemia in Denmark, with Aggregatibacter spp in second place. Keywords: Epidemiology, Incidence, Age, Sex, Haemophilus, Aggregatibacte

Danish Whole-Genome-Sequenced Candida albicans and Candida glabrata Samples Fit into Globally Prevalent Clades

Candida albicans and Candida glabrata are opportunistic fungal pathogens with increasing incidence worldwide and higher-than-expected prevalence in Denmark. We whole-genome sequenced yeast isolates collected from Danish Clinical Microbiology Laboratories to obtain an overview of the Candida population in the country. The majority of the 30 C. albicans isolates were found to belong to three globally prevalent clades, and, with one exception, the remaining isolates were also predicted to cluster with samples from other geographical locations. Similarly, most of the eight C. glabrata isolates were predicted to be prevalent subtypes. Antifungal susceptibility testing proved all C. albicans isolates to be susceptible to both azoles and echinocandins. Two C. glabrata isolates presented azole-resistant phenotypes, yet all were susceptible to echinocandins. There is no indication of causality between population structure and resistance phenotypes for either species