Hiding in plain sight-wildlife as a neglected reservoir and pathway for the spread of antimicrobial resistance: a narrative review.

Antimicrobial resistance represents a global health problem, with infections due to pathogenic antimicrobial resistant bacteria (ARB) predicted to be the most frequent cause of human mortality by 2050. The phenomenon of antimicrobial resistance has spread to and across all ecological niches, and particularly in livestock used for food production with antimicrobials consumed in high volumes. Similarly, hospitals and other healthcare facilities are recognized as significant 'hotspots' of ARB and antimicrobial resistance genes (ARGs); however, over the past decade, new and previously overlooked ecological niches are emerging as hidden reservoirs of ARB/ARGs. Increasingly extensive and intensive industrial activities, degradation of natural environments, burgeoning food requirements, urbanization, and global climatic change have all dramatically affected the evolution and proliferation of ARB/ARGs, which now stand at extremely concerning ecological levels. While antimicrobial resistant bacteria and genes as they originate and emanate from livestock and human hosts have been extensively studied over the past 30 years, numerous ecological niches have received considerably less attention. In the current descriptive review, the authors have sought to highlight the importance of wildlife as sources/reservoirs, pathways and receptors of ARB/ARGs in the environment, thus paving the way for future primary research in these areas.

Occurrence of plasmid-mediated quinolone resistance determinants among Escherichia coli strains isolated from animals in Tunisia: Specific pathovars acquired qnr genes.

OBJECTIVES: The aim of this study was to characterise Escherichia coli strains harbouring plasmid-mediated quinolone resistance (PMQR) genes recovered from various samples (n = 116) from healthy and diarrhoeic animals in Tunisia. METHODS: All nalidixic acid-resistant E. coli isolates were screened for the presence of PMQR genes. Isolates positive for PMQR genes were investigated by PCR for chromosomal mutations in the quinolone resistance-determining regions (QRDRs) of GyrA and ParC, the presence of class 1 and class 2 integrons, genes encoding tetracycline and sulfonamide resistance, genes encoding virulence factors, and phylogenetic group. Genetic relationships was determined by pulsed-field gel electrophoresis (PFGE). RESULTS: Amongst 51 nalidixic acid-resistant isolates, 9 harboured PMQR genes (5 co-harbouredqnrS1 and qnrB1, 3 harboured qnrS1 and 1 harboured qnrB1). Two types of mutation in the QRDR of GyrA were observed: S83L and D87N (eight isolates) and S83L (one isolate). For the QRDR of ParC, the substitution S80I was observed in four isolates. A class 1 integron was found in six isolates. The tetA or tetB gene was observed in six isolates and both tetA and tetB were co-harboured by two isolates. The sul1, sul2 and sul3 genes were detected in six, four and one isolates, respectively. According to the presence of specific virulence genes, the nine strains were classified as UPEC (5), EAEC (3) and EPEC (1). Three isolates from turkey faeces were clonally related by PFGE. CONCLUSION: These findings highlight the plausible role of the avian industry as a reservoir of human pathogenic E. coli strains.

Genetic characterisation of Staphylococcus aureus isolated from milk and nasal samples of healthy cows in Tunisia: First report of ST97-t267-agrI-SCCmecV MRSA of bovine origin in Tunisia.

OBJECTIVES: This study aimed to screen for and characterise methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in nasal swabs and milk from healthy cows from different regions in Tunisia. METHODS: A total of 141 Staphylococcus spp. isolates were recovered from milk and nasal samples of cows. S. aureus isolates were further characterised by determining their antimicrobial susceptibilities, genes encoding antimicrobial resistance and virulence factors, biofilm production, agr type and PFGE. spa and SCCmec typing and MLST were also performed for the MRSA isolate. RESULTS: Twenty-seven isolates (19.1%) were identified as S. aureus, of which 26 were MSSA and 1 was MRSA. The MSSA isolates were resistant to penicillin (73.1%), fusidic acid (61.5%), clindamycin (34.6%) and erythromycin (34.6%). The MRSA isolate, from a milk sample, was resistant to cefoxitin, penicillin, fusidic acid, amikacin and clindamycin. Twenty-five isolates (92.6%) had at least one enterotoxin gene. Only four isolates (14.8%) were positive for the tsst-1 gene. Genes encoding the exfoliative toxins D and A were detected in 9 (33.3%) and 6 (22.2%) isolates, respectively. The single MRSA isolate and 22 MSSA isolates were biofilm-producers on Congo red agar plates. Twelve pulsotypes were identified amongst 25 MSSA isolates revealing the clonal diversity of these isolates; however, one MSSA isolate was identified as CC398. The MRSA isolate was PVL-negative and was typed as ST97-t267-agrI-SCCmecV. CONCLUSION: Contamination of milk with S. aureus, especially enterotoxin- and TSST-1-positive strains, poses a potential public-health threat. This is the first report of MRSA of bovine origin in Tunisia.

An epidemological study on Peste des petits ruminants in Tripoli Region, Lybia.

A cross­sectional study was conducted in Libya in 7 areas of Tripoli to determine the seroprevalence of Peste des Petits Ruminants (PPR) Virus (PPRV) in small ruminants (sheep and goats) between June and August 2013, and to identify the potential risk factors associated with the infection. The study involved 10% of small ruminant herds with ≥50 animals in the Tripoli region. They were selected randomly (15 herds), and 35 to 58 samples, depending on its size, were collected from each selected herd. Seven­hundred and twenty­one serum samples from unvaccinated animals (601 of sheep and 120 of goats) were collected and then tested using cELISA commercial kit in the National Center of Animal Health Laboratory in Tripoli, Libya. The overall seroprevalence was 46.7% [(sheep 44.3% (266/601) and goats 59.2% (71/120)]. Mean within­herd prevalence was 48.5% (95% CI: 32.1% ­ 64.8%), and the herd prevalence was 93.3% (14/15). Various risk factors at the animal and herd levels were analysed by multivariable logistic regression model (forward stepwise). The results identified breed, source of animal, and region as significant risk factors (p< 0.05). As for the source of new animal to the farm, PPRV seroprevalence was highest in illegally imported animals (90.9%), followed by the seroprevalence in animal legitimately acquired (55.8%), and by the seroprevalence in animals belonging to the same herd (4.7%). The seroprevalence among breeds was 69.5% (228÷328) in illegally imported animals, whereas 27.7% (109÷393) was found to be in local breed. Seroprevalence in the areas considered in this study was higher (66.2%) in Al­Mashroa area followed by Ein­zara (57.8%), Arada (50%), Ben­Own (47%), AL­Naem (37.5), Ber­Alalem (24.5) and in Tajora (0%). The results indicated that PPRV virus was actively circulating in Tripoli regions and that the illegal importing of animals was the main source of spreading PPR in Tripoli regions, showing that better efforts should be made to raise public awareness with respect to biosecurity.

Diverse Escherichia coli pathovars of phylogroups B2 and D isolated from animals in Tunisia.

INTRODUCTION: The virulent Escherichia coli strains responsible for extraintestinal infections were mainly belonged to B2 and D phylogroups. However, no past studies have determinate via the presence of virulence genes the frequency of E. coli pathovars recovered from animals housed in farms in Tunisia. The aims of this study were to investigate 26 E. coli isolated from healthy and diarrheic animals and to determinate via the presence of virulence genes the frequency of pathovars. METHODOLOGY: Twenty-six E. coli isolates of phylogroups B2 (n = 14), B22 (n = 9), B23 (n = 5), and D2 (n = 12) were characterized. Genes encoding virulence factors (fimH,eaeA,aggC,papC, papG allele III, hlyA, east1, cnf1, exhA,stx1, stx2, iutA, fyuA, ibeA,and ipaH), and antibiotic resistance as well as class 1 and 2 integrons were searched by polymerase chain reaction (PCR). The genetic relationship of isolates was done by PFGE. RESULTS: According to the occurrence of specific genes the 26 isolates were classified as:9 EAEC, 2 EHEC, 4 UPEC, 3 EPEC/EHEC and 1 NTEC. Therefore, 2 Ex-PEC and 5 APEC were presented amongst our strains. Some isolates (12) were clonal and the remaining was unrelated. CONCLUSIONS: Higher diversity of pathovars which carried diverse combinations of virulence genes in healthy isolates. In addition, it seems that the infections were caused by different mechanisms.

Occurrence of bla CTX-M-1, qnrB1 and virulence genes in avian ESBL-producing Escherichia coli isolates from Tunisia.

Avian ESBL-producing Escherichia coli isolates have been increasingly reported worldwide. Animal to human dissemination, via food chain or direct contact, of these resistant bacteria has been reported. In Tunisia, little is known about avian ESBL- producing E. coli and further studies are needed. Seventeen ESBL-producing Escherichia coli isolates from poultry feces from two farms (Farm 1 and farm 2) in the North of Tunisia have been used in this study. Eleven of these isolates (from farm 1) have the same resistance profile to nalidixic acid, sulfonamides, streptomycin, tetracycline, and norfloxacine (intermediately resistant). Out of the six isolates recovered from farm 2, only one was co-resistant to tetracycline. All isolates, except one, harbored bla CTX-M-1 gene, and one strain co-harbored the bla TEM-1 gene. The genes tetA and tetB were carried, respectively, by 11 and 1 amongst the 12 tetracycline-resistant isolates. Sulfonamides resistance was encoded by sul1, sul2, and sul3 genes in 3, 17, and 5 isolates, respectively. The qnrB1 was detected in nine strains, one of which co-harbored qnrS1 gene. The search for the class 1 and 2 integrons by PCR showed that in farm 1, class 1 and 2 integrons were found in one and ten isolates, respectively. In farm 2, class 1 integron was found in only one isolate, class 2 was not detected. Only one gene cassette arrangement was demonstrated in the variable regions (VR) of the 10 int2-positive isolates: dfrA1- sat2-aadA1. The size of the VR of the class 1 integron was approximately 250 bp in one int1-positive isolate, whereas in the second isolate, no amplification was observed. All isolates of farm 1 belong to the phylogroup A (sub-group A0). However, different types of phylogroups in farm 2 were detected. Each of the phylogroups A1, B22, B23 was detected in one strain, while the D2 phylogroup was found in 3 isolates. The virulence genes iutA, fimH, and traT were detected in 3, 7, and 3 isolates, respectively. Two types of gene combination were detected: iutA+fimH+traT in 3 isolates and iutA+fimH in one isolate. The isolates recovered in farm 1 showed the same profile of PFGE macro-restriction, while isolates of farm 2 presented unrelated PFGE patterns. We conclude that these avian ESBL-producing E. coli isolates show homo- and heterogenic genetic background and that plasmids harboring ESBL genes could be involved in the dissemination of this resistance phenotype.