Linezolid is a critically important antibiotic used to treat human infections caused by MRSA and VRE. While linezolid is not licensed for food-producing animals, linezolid-resistant (LR) isolates have been reported in European countries, including Belgium.To: (i) assess LR occurrence in staphylococci and enterococci isolated from different Belgian food-producing animals in 2019 through selective monitoring; and (ii) investigate the genomes and relatedness of these isolates.Faecal samples (n = 1325) and nasal swab samples (n = 148) were analysed with a protocol designed to select LR bacteria, including a 44-48 h incubation period. The presence of LR chromosomal mutations, transferable LR genes and their genetic organizations and other resistance genes, as well as LR isolate relatedness (from this study and the NCBI database) were assessed through WGS.The LR rate differed widely between animal host species, with the highest rates occurring in nasal samples from pigs and sows (25.7% and 20.5%, respectively) and faecal samples from veal calves (16.4%). WGS results showed that LR determinants are present in a large diversity of isolates circulating in the agricultural sector, with some isolates closely related to human isolates, posing a human health risk.LR dedicated monitoring with WGS analysis could help to better understand the spread of LR. Cross-selection of LR transferable genes through other antibiotic use should be considered in future action plans aimed at combatting antimicrobial resistance and in future objectives for the rational use of antibiotics in a One Health perspective.
The incidence of nosocomial infections due to carbapenem-resistant Klebsiella pneumoniae is increasing worldwide. Whole-genome sequencing (WGS) can help elucidate the transmission route of nosocomial pathogens.We combined WGS and epidemiological data to analyze an outbreak of New Delhi metallo-β-lactamase (NDM)-producing K. pneumoniae that occurred in 2 Belgian hospitals situated about 50 miles apart. We characterized 74 NDM-producing K. pneumoniae isolates (9 from hospital A, 24 from hospital B, and 41 contemporary isolates from 15 other Belgian hospitals) using pulsed-field gel electrophoresis and WGS.A K. pneumoniae sequence type 716 clone was identified as being responsible for the outbreak with all 9 strains from hospital A and 20 of 24 from hospital B sharing a unique pulsotype and being clustered together at WGS (compared with 1 of 41 isolates from other Belgian hospitals). We identified the outpatient clinic of hospital B as the probable bridging site between the hospitals after combining epidemiological, phylogenetic, and resistome data. We also identified the patient who probably caused the transmission. In fact, all but 1 strain from hospital A carried a Tn1331-like transposon, whereas none of the hospital B isolates did. The patient from hospital A who did not have the Tn1331-like transposon was treated at the outpatient clinic of hospital B on the same day as the first NDM-producing K. pneumoniae-positive patient from hospital B.The results from our WGS-guided investigation highlight the importance of implementing adequate infection control measures in outpatient settings, especially when healthcare delivery moves from acute care facilities to outpatient clinics.
All Staphylococcus aureus isolates (n=31) that caused bacteraemia in a Spanish geriatric hospital during 1996-2006 were analysed by a simple, rapid and inexpensive PCR technique based on variations in the hsdS1 and hsdS2 genes encoding the sequence recognition subunits of the Sau1 restriction-modification (RM) system. An equal number of isolates collected from surgical wounds over the same time period (control group) were similarly characterized. The RM test allocated 75 % of the isolates to the six major clonal complexes (CC1, CC5, CC8, CC22, CC30 and CC45) for which it was developed. However, recognition of minor CCs and precise identification of the circulating clones required more powerful and comprehensive techniques such as spa typing and multilocus sequence typing (MLST), which are more demanding and expensive. The RM test is not intended to replace spa or MLST typing, but may be of use when time, technical and/or financial resources are limited. Overall, nine and seven CCs were detected in bloodstream and wound isolates, respectively. In both groups, CC5 was the most frequent (35.5 % each), followed by CC45 or CC8 (22.6 and 32.3 % of bloodstream and wound isolates, respectively). The frequency of meticillin resistance was lower in bloodstream (16.1 %) than in wound (51.6 %) isolates (P=0.0025). Among the former, sequence type (ST) 5-staphylococcal cassette chromosome mec (SCCmec) II, ST5-SCCmec IV, ST45-SCCmec IV and ST125-SCCmec IV (now dominant in Spanish hospitals) clones were found. Among the wound isolates, nine meticillin-resistant clones were represented, with three of them (ST125-SCCmec III, ST125-SCCmec V and ST14-SCCmec V) being newly described.
Resistance is notoriously high in Asia but may not entirely explain therapeutic failures. Specific modes of bacterial life, such as biofilm or intracellular survival, may also contribute to the persistent and/or recurrent character of infections. Most Staphylococcus aureus isolates form biofilm and many survive and even thrive intracellularly. We collected 36 nonduplicate S. aureus isolates (including 18 methicillin-resistant S. aureus) from patients with clinical evidence of persistent or recurrent infections in a large tertiary Vietnamese hospital. We examined their antibiotic resistance profile (minimal inhibitory concentration determination) and clonal relatedness (spa and agr typing, pulsed field gel electrophoresis profiles). We then assessed the activity of moxifloxacin in both biofilms and infected phagocytes (moxifloxacin previously proved to be one of the most active antibiotics against reference strains in these models). spa-types t189 and t437 and agr group I were the most frequent. Among the 36 isolates, 30 were multidrug resistant but 30 were recovered from patients having received an active drug. All tested isolates produced biofilm and survived inside phagocytes. At its human Cmax, moxifloxacin was inactive on biofilms made by moxifloxacin-susceptible as well as moxifloxacin-resistant isolates. It caused only a modest intracellular colony-forming unit decrease against moxifloxacin-susceptible isolates and was inactive against those resistant to moxifloxacin. While our data confirm for this collection the high resistance levels and prevalence of endemic spa- or agr- types in Asia, they show that tolerance in both biofilm and phagocytes are correlated and markedly limit moxifloxacin activity, which goes in line with the suggested role of these modes of life in persistence or recurrence of infections.
An outbreak of intravascular catheter-related infections by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in calves in an animal teaching hospital is reported. Pulsed-field gel electrophoresis was used for strain typing to determine the origin and dissemination of these strains. All 19 strains harboured the blaCTX-M-14, and six strains also overexpressed their chromosomal AmpC gene. Evidence on the introduction of the strain from a beef herd, experiencing neonatal diarrhoea and increased mortality, to the clinic through admission of diarrhoeic calves was provided. Strains isolated from phlebitis cases from other herds up to 5 months later showed a high similarity with the initial strain, suggesting that the strain had become nosocomial. The catheter infections with ESBL/AmpC-producing E. coli resulted in a prolonged hospitalization, increased anti-microbial use and mortality. This report points towards the potential dangers of the emergence of ESBL/AmpC-producing bacteria in susceptible food animals and warns farmers and veterinarians for the facility by which they are introduced into another environment.
The aim of this study was to estimate the in vitro activity of ceftaroline against clinical Staphylococcus aureus isolates collected during national surveillance in Belgian acute-care hospitals. Ceftaroline-resistant isolates were further investigated for their resistance mechanisms. From October 2013 to March 2014, 155 laboratories of Belgian acute-care hospitals were invited to send to the National Reference Centre—Staphylococcus aureus (Belgium) up to five non-duplicate S. aureus including three MRSA and two MSSA from hospitalized patients. Isolates were analysed by spa typing, SCCmec typing (for MRSA) and PCR for detection of 16S-mecA-nuc and 16S-mecC. MICs of oxacillin, cefoxitin and ceftaroline were determined by the broth microdilution method. The nucleotide sequences of mecA, native pbp and gdpP genes of isolates with reduced susceptibility to ceftaroline were analysed for the presence of mutations responsible for amino acid substitutions. Ninety-nine percent of isolates, including MRSA (n = 284) and MSSA (n = 131), were susceptible to ceftaroline. Only four MRSA isolates showed resistance to ceftaroline (MIC = 2 mg/L). These four isolates belonged to lineages CC5 (n = 1), CC22 (n = 2) and CC8 (n = 1). Two isolates (CC22 and CC8) carried mutations in mecA, as well as in other pbp genes. The remaining isolates carried mutations in native pbp genes or in gdpP. This is the first Belgian in vitro survey on ceftaroline activity against S. aureus. This antibiotic showed excellent activity against MRSA and MSSA, and only a few MRSA isolates with resistance were found. Reduced susceptibility to ceftaroline seems a complex phenomenon due to the accumulation of mutations in genes involved in β-lactam tolerance.
