Occurrence and persistence of multidrug-resistant Enterobacterales isolated from urban, industrial and surface water in Monastir, Tunisia.

The One Health approach of antimicrobial resistance highlighted the role of the aquatic environment as a reservoir and dissemination source of resistance genes and resistant bacteria, especially due to anthropogenic activities. Resistance to extended-spectrum cephalosporins (ESC) conferred by extended-spectrum beta-lactamases (ESBLs) in E. coli has been proposed as the major marker of the AMR burden in cross-sectoral approaches. In this study, we investigated wastewater, surface water and seawater that are subjected to official water quality monitoring in Monastir, Tunisia. While all but one sample were declared compliant according to the official tests, ESC-resistant bacteria were detected in 31 (19.1 %) samples. Thirty-nine isolates, coming from urban, industrial and surface water in Monastir, were collected and characterized using antibiograms and whole-genome sequencing. These isolates were identified as 27 Escherichia coli (69.3 %) belonging to 13 STs, 10 Klebsiella pneumoniae (25.6 %) belonging to six STs, and two Citrobacter freundii (5.1 %). We observed the persistence and dissemination of clones over time and in different sampling sites, and no typically human-associated pathogens could be identified apart from one ST131. All isolates presented a blaCTX-M gene - blaCTX-M-15 (n = 22) and blaCTX-M-55 (n = 8) being the most frequent variants - which were identified on plasmids (n = 20) or on the chromosome (n = 19). In conclusion, we observed ESC resistance in rather ubiquitous bacteria that are capable of surviving in the water environment. This suggests that including the total coliform count and the ESBL count as determined by bacterial growth on selective plates in the official monitoring would greatly improve water quality control in Tunisia.

Clonal, Plasmidic and Genetic Diversity of Multi-Drug-Resistant Enterobacterales from Hospitalized Patients in Tripoli, Libya.

Resistance to extended-spectrum cephalosporins (ESC) and carbapenems in Enterobacterales is a major issue in public health. Carbapenem resistance in particular is associated with increased morbidity and mortality. Moreover, such resistance is often co-harbored with resistance to non-beta-lactam antibiotics, and pathogens quickly become multi-drug-resistant (MDR). Only a few studies have been published on AMR in Libyan hospitals, but all reported worrisome results. Here, we studied 54 MDR isolates that were collected from 49 patients at the Tripoli University Hospital between 2019 and 2021. They were characterized using phenotypic methods, PCR and PFGE, and a sub-set of isolates were short- and long-read whole-genome sequenced. The results showed the frequent occurrence of Klebsiella pneumoniae (49/54), among which several high-risk clones were responsible for the spread of resistance, namely, ST11, ST17, ST101 and ST147. ESC and carbapenem resistance was due to a wide variety of enzymes (CTX-M, OXA-48, NDM, KPC), with their corresponding genes carried by different plasmids, including IncF-IncHI2 and IncF-IncR hybrids. This study highlights that implementation of infection prevention, control and surveillance measures are needed in Libya to fight against AMR.

Staphylococcus aureus Ventilator-Associated Pneumonia: A Study of Bacterio-Epidemiological Profile and Virulence Factors.

Ventilator-associated pneumonia (VAP) represents a major cause of nosocomial infections in the intensive care units in which Staphylococcus aureus is frequently involved. Better knowledge of this pathogen is required in order to enhance the patient's treatment and care. In this article, we studied the bacteriological profile and virulence factors of S. aureus-related VAP on a 3-year period. We included a collection of S. aureus strains (n = 35) isolated from respiratory samples from patients diagnosed with VAP in the intensive care units. We studied the bacteriological aspects and we searched for the presence of virulence factors (SpA, FnbpA, Hla, and PVL genes) in the strains, and we also studied the clinical and biological aspects of the infections. The average age of our patients was of 36 years and they were predominantly males (sex ratio = 3.37). A severe head trauma or a history of coma was noted in 73.43% of the patients. The average duration of ventilation was 29 days. Among the studied strains, five were Methicillin-resistant S. aureus of which three expressed the mecA gene. Overall, the Hla gene was detected in 85.7% of the strains and it was more prevalent in Methicillin-susceptible than Methicillin-resistant strains (93.3% versus 40%; P = 0.014). FnbpA, Spa, and PVL genes were detected, respectively, in 80%, 45.7%, and 20% of the strains. Therefore, our studied strains were essentially associated with the production of Hla and FnbpA genes. It is, however, important to elucidate their expression in order to establish their role in the VAP pathogenesis.

Dynamics and molecular features of OXA-48-like-producing Klebsiella pneumoniae lineages in a Tunisian hospital.

OBJECTIVES: The aim of this study was to elucidate the molecular features of genes, plasmids and clones of OXA-48-like producingKlebsiella pneumoniae isolates recovered in Sahloul Hospital (Sousse, Tunisia) in the period 2012-2014. METHODS: In vitro antimicrobial susceptibility testing, S1 nuclease pulsed-field gel electrophoresis (S1-PFGE), Southern blotting and PCR-based replicon typing (PBRT) were performed. Extended-spectrum ß-lactamase (ESBL) and carbapenemases genes were detected by PCR and sequencing. The clonality of isolates was assessed by PFGE and multilocus sequence typing (MLST). RESULTS: Klebsiella pneumoniae accounted for 26.8% (1095/4083) of clinical Enterobacterales isolates identified during 2012-2014, of which 21.9% (240/1095) were resistant to carbapenems, mostly harbouring blaOXA-48-like genes (196/240; 81.7%). Plasmid analysis showed that blaOXA-204 and blaOXA-48 were mostly carried by IncA/C and IncL plasmids, respectively. The current data highlight the dominance of two ST101 and ST147 lineages spreading OXA-48 and OXA-204, respectively, through successive clonal spreads at this hospital. In addition, a large diversity of other K. pneumoniae lineages was also identified, such as ST15, ST36 and ST525 spreading OXA-48 as well as ST340, ST2032, ST301, ST199 and ST1561 spreading OXA-48 or OXA-204, constituting a reservoir of possible dominant clones in the future. CONCLUSION: This study reports the full molecular characterisation of carbapenem resistance in K. pneumoniae and the predominance of a few clones responsible for the dissemination of OXA-48 and OXA-204 enzymes in a Tunisian hospital.

Genomic Insights into Colistin-Resistant Klebsiella pneumoniae from a Tunisian Teaching Hospital.

The emergence of colistin-resistant Klebsiella pneumoniae (CoRKp) is a public health concern, since this antibiotic has become the last line of treatment for infections caused by multidrug-resistant (MDR) Gram negatives. In this study, we have investigated the molecular basis of colistin resistance in 13 MDR K. pneumoniae strains isolated from 12 patients in a teaching hospital in Sousse, Tunisia. Whole-genome sequencing (WGS) was used to decipher the molecular mechanism of colistin resistance and to identify the resistome of these CoRKp isolates. It revealed a genome of ca. 5.5 Mbp in size with a G+C content of 57%, corresponding to that commonly observed for K. pneumoniae These isolates belonged to the 5 different sequence types (ST11, ST15, ST101, ST147, and ST392), and their resistome was composed of acquired ß-lactamases, including extended-spectrum beta-lactamase and carbapenemase genes (blaCTX-M-15, blaOXA-204, blaOXA-48, and blaNDM-1 genes), aminoglycoside resistance genes [aac(6')Ib-cr, aph(3″)-Ib, aph(6)-Id, and aac(3)-IIa], and fosfomycin (fosA), fluoroquinolone (qnr-like), chloramphenicol, trimethoprim, and tetracycline resistance genes. All of the isolates were identified as having a mutated mgrB gene. Mapping reads with reference sequences of the most common genes involved in colistin resistance revealed several modifications in mgrB, pmr, and pho operons (deletions, insertions, and substitutions) likely affecting the function of these proteins. It is worth noting that among the 12 patients, 10 were treated with colistin before the isolation of CoRKp No plasmid encoding mcr-1 to mcr-5 genes was found in these isolates. This study corresponds to the first molecular characterization of a collection of CoRKp strains in Tunisia and highlights that the small-transmembrane protein MgrB is a main mechanism for colistin resistance in K. pneumoniae.

[Association between bacterial resistance and antimicrobial consumption]. / Relations entre la résistance bactérienne et la consommation des antibiotiques.

UNLABELLED: The evolution of multidrug resistance remains an alarming topic due to selection pressure related to the inappropriate use of antibiotics. OBJECTIVES: Our work is in this perspective and focuses on the evolution of the consumption of antibiotics active on gram-negative bacilli, and the evolution of bacterial resistance. MATERIALS AND METHODS: International indicator of antibiotic consumption was based on the method of Defined Daily Dose reported to the number of days of hospitalization. The search for a correlation between bacterial resistance and antibiotic consumption was conducted by the Spearman test. RESULTS: A statistically significant correlation was identified between the rates of enterobacteriaceae resistant to 3(rd) generation cephalosporin, particularly those secreting beta-lactamases with extended spectrum, and consumption of 3(rd) generation cephalosporin (p= 0.002) and imipenem (p= 0.04). Also, a statistically significant relationship between the multi-resistant bacteria and the rate of consumption of colistin (p= 0.041) and fluoroquinolones (p= 0.002) was also reported in this study. CONCLUSION: Monitoring of both evolution of multidrug resistance and the use of antibiotics helps us to better understand the situation and establish more efficient antibiotic protocols.