Recovery of Bacillus mycoides, B. pseudomycoides and Aeromonas hydrophila from common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss) with gill disease.

During a 3-month period from June to the end of August 2016, ~5% mortalities were observed in a farm with rainbow trout (Oncorhynchus mykiss Walbaum) and one farm of common carp (Cyprinus carpio L.) in Bulgaria. The disease was manifested by gill ulcers/rot, asphyxiation and bloody ascites. Aeromonas hydrophila was isolated from the internal organs of all the diseased fish. Bacillus mycoides or B. pseudomycoides were recovered from the gill lesions on diseased carp and rainbow trout, respectively, with identification achieved by conventional phenotyping and by sequencing of the 16S rRNA gene. In vivo experiments confirmed that all three organisms were pathogenic to rainbow trout.

Recovery of Hafnia alvei from diseased brown trout, Salmo trutta L., and healthy noble crayfish, Astacus astacus (L.), in Bulgaria.

Hafnia alvei was isolated in Bulgaria from healthy noble crayfish, Astacus astacus (L.), and then from farmed diseased brown trout, Salmo trutta L., with signs of haemorrhagic septicaemia. The isolates were identified initially with conventional phenotyping and commercial Merlin Micronaut and API 20E rapid identification systems, followed by sequencing of the 16S rRNA gene. Hafnia alvei Bt1, Bt2 and Aa4 were of low virulence to rainbow trout and brown trout, although cytotoxicity was demonstrated by Bt1 and Bt2, but not by Aa4.

Rise of multidrug-resistant Streptococcus pneumoniae clones expressing non-vaccine serotypes among children following introduction of the 10-valent pneumococcal conjugate vaccine in Bulgaria.

OBJECTIVES: Pneumococcal conjugate vaccines (PCVs) have reduced the incidence of pneumococcal disease, but non-vaccine serotypes are of concern, particularly if antimicrobial-resistant. This study retrospectively evaluated the serotype-specific clonality of paediatric multidrug-resistant (MDR) invasive and non-invasive Streptococcus pneumoniae isolates collected following PCV10 introduction (2011-2017) in Bulgaria. METHODS: Capsular types, drug resistance patterns and multilocus sequence typing (MLST) of the most common MDR S. pneumoniae serotypes sampled from children were determined. RESULTS: Overall, the rate of MDR pneumococci was 44.6% (107/240). The most common serotypes among MDR strains were 19F (25.2%), 19A (19.6%), 6C (13.1%), 6A and 23A (6.5% each) and 15A (4.7%), contributing 75.7% of all MDR strains. With the exception of serotype 19F, the remaining serotypes were non-PCV10 types. Among MDR pneumococci, the most frequently found sequence types were ST320 (30.4%; 19A and 19F), ST386 (12.7%; 6C and 6A) and ST8029 (5.1%; 23A). The majority of MDR STs (74.7%) belonged to PMEN clonal complexes, of which the most common were CC320 (Taiwan19F-14), CC315 (Poland6B-20) and CC180 (Netherlands3-31), accounting for 43.0%, 13.9% and 5.1%, respectively. In the post-vaccine period, a shift in the genetic structure of serotype 19A was found, with a significant increase of PMEN-14 (CC320) and a concurrent decrease of the major clone Denmark14-32 (CC230) observed prior to PCV10 introduction in Bulgaria. CONCLUSIONS: Clonality was found behind the wide distribution of MDR capsular types 19A, 6C, 23A and 3 following vaccine introduction, and a highly multiresistant and virulent clone Taiwan19F-14/ST320 has emerged as a common pathogen in children.