Antibiotic resistance and virulence genes in Enterococcus species isolated from raw and processed seafood

This study evaluated the antibiotic resistance characteristics and virulence genes of enterococci isolated from raw and processed seafood sold in the Marmara Region, Turkey. In this context, the enterococcal load was determined as between 1.0 and 2.5 log CFU/g in 39 of a total of 397 samples. It was determined that 117 strains isolated from the samples belonged to Enterococcus gallinarum, E. casseliflavus, E. durans, E. faecium, and E. faecalis species. Erythromycin, tetracycline, streptomycin, and gentamicin resistance was observed, whereas the tetM, ermB, aac(6')-aph(2'')-la genes were found in a majority of the isolates. It was also determined that the isolates carried the agg2 and gelE virulence genes. When all these results are evaluated, the presence of these isolates in aquatic products may pose a risk in terms of food safety and public health.

Bloodstream infections in neutropenic patients with haematological malignancies

BACKGROUND

Patients with haematological malignancies have higher risk of acquiring bloodstream infection (BSI). Neutropenia resulting from cytotoxic chemotherapy is the most common risk factor. Infections can progress rapidly with poor outcomes. Understanding the epidemiology may enable prevention and effective management. We investigated and compared the incidence of BSI amongst patients with haematological malignancies and neutropenia and examined the changing spectrum of organisms, and their antimicrobial profiles.

METHODS

BSI data between July 1st 2009 and June 30th 2015 was reviewed.

RESULTS

Three hundred and fifty five BSI were identified in 255 neutropenic patients. Acute myeloid leukaemia (AML) accounted for 40%, Non-Hodgkin's lymphoma for 22% and Acute lymphocytic leukaemia (ALL) for 11.8%. A neutrophil count of <500 cells/μL was present in 93.2%. The overall incidence was 5.40 BSI per 1000 Haematology Occupied Bed days (OBD). Viridans streptococci and Enterococcus species were the most predominant Gram-positives. Vancomycin resistant Enterococcus faecium (VRE) emerged as the predominant Enterococcus species during the study period. Escherichia coli was the most predominant Gram-negative and Extended-spectrum beta-lactamases (ESBL) were detected in 7.1% of isolates. Amongst the Enterobacteriaceae and Pseudomonas aeruginosa dual resistance to Piperacillin-tazobactam and Gentamicin was detected in 5.4%.

CONCLUSION

Our incidence of BSI was 5.40 per 1000 OBD, however variability in reporting of rates in neutropenic patients with haematological malignancies makes comparison between studies difficult, highlighting the need for rate reporting standardization. The epidemiology of organisms causing BSI has changed over time. There is a trend towards an increasing incidence of VRE and multidrug resistant Gram-negatives.

Antimicrobial Resistance, Virulence Determinants, and Biofilm Formation of Enterococcus Species From Ready-to-Eat Seafood

Enterococcus species form an important population of commensal bacteria and have been reported to possess numerous virulence factors considered significantly important in exacerbating diseases caused by them. The present study was designed to characterize antibiotic-resistant and virulent enterococci from ready-to-eat (RTE) seafood. A total of 720 RTE shrimp samples comprising sauced shrimp (n = 288), boiled shrimp (n = 216), and smoked shrimp (n = 216) obtained from open markets in Delta State, Nigeria, were assessed. Standard classical methods and polymerase chain reaction (PCR) were used in identifying the Enterococcus species. Potential virulence factors (β-hemolysis, gelatinase activity, S-layer, and biofilm formation) were assessed using standard procedures. The antibiotic susceptibility profile of the identified enterococci isolates was assayed using the Kirby–Bauer disc diffusion method. PCR was further used to screen selected antibiotic resistance and virulence genes. Prevalence of Enterococcus species from shrimp varieties is as follows: sauced, 26 (9.03%); boiled, 6 (2.78%); and smoked, 27 (12.50%), with an overall prevalence of 59 (8.19%) based on the occurrence of black hallow colonies after incubation. Enterococcus species detected include E. faecalis, 17 (28.8%); E. faecium, 29 (49.2%); E. gallinarum, 6 (10.2%); E. casseliflavus, 2 (3.4%); E. hirae, 3 (5.1%); and E. durans, 2 (3.4%). Biofilm occurrence among the shrimp varieties is as follows: 19/26 (73.1%) for sauced shrimps, 5/6 (83.3%) for boiled shrimps, and 16/27 (59.3%) for smoked shrimps. The phenotypic expression of the enterococci virulence revealed the following: S-layer, 59 (100%); gelatinase production, 19 (32.2%); and β-hemolysis, 21 (35.6%). An average of 3–11 virulence genes were detected in the Enterococcus species. The resistance profile of Enterococcus species is as follows: erythromycin, 29 (49.2%); vancomycin, 22 (37.3%); and tetracycline, 27 (45.8%). The frequency of occurrence of antibiotic resistance genes from the phenotypic resistant enterococci isolates to the macrolide, glycopeptide, and tetracycline antibiotics is as follows: ermA, 13/29 (44.8%); vanA, 14/22 (63.6%); tetA, 14/27 (51.9%); tetM, 15/27 (55.6%); ermB, 4/29 (13.8%); and vanB, 5/22 (22.7%). Findings from this study reveal the antibiotic resistance of enterococci strains of such species as E. durans, E. casseliflavus, E. gallinarum, and E. hirae. This study further revealed that RTE food products are reservoirs of potential virulent enterococci with antibiotic-resistant capabilities. This provides useful data for risk assessment and indicates that these foods may present a potential public health risk to consumers.

MALDI-TOF MS meets WGS in a VRE outbreak investigation

The use of MALDI-TOF MS (matrix-assisted laser desorption/ ionization-time of flight mass spectrometry) and WGS (whole genome sequencing) has been described for identification and strain relatedness determination. We describe the complementary use of MALDI-TOF MS and WGS in a VRE (vancomycin-resistant enterococci) outbreak investigation, and discuss some of the challenges with defining strain similarity across these two platforms. Although both assays indicated multiple clusters involved in the outbreak of vancomycin resistant Enterococcus faecium isolates from positive blood cultures of four haematology-oncology patients, the small cohort and discrepancies between findings indicate the limitations of MALDI-TOF MS and the cautious interpretation of MALDI-TOF MS dendrograms during outbreaks. For definitive determination of the evolutionary distance between isolates, WGS can be used.