In the last few years, different surveillances have been published in Africa, especially in northern countries, regarding antimicrobial resistance among husbandry animals. Information is still ...scarce, but the available data show a worrying picture. Although the highest resistance rates have been described against tetracycline, penicillins and sulphonamides, prevalence of plasmid‐mediated quinolone resistance genes and extended spectrum β‐lactamase (ESBL) are being increasingly reported. Among ESBLs, the CTX‐M‐1 group was dominant in most African surveys. Within this group, CTX‐M‐15 was the main variant both in animals and humans, except in Tunisia where CTX‐M‐1 was more frequently detected among Escherichia coli from poultry. Certain blaCTX‐M‐15‐harbouring clones (ST131/B2 or ST405/D) are mainly identified in humans, but they have also been reported in livestock species from Tanzania, Nigeria or Tunisia. Moreover, several reports suggest an inter‐host circulation of specific plasmids (e.g. blaCTX‐M‐1‐carrying IncI1/ST3 in Tunisia, IncY‐ and Inc‐untypeable replicons co‐harbouring qnrS1 and blaCTX‐M‐15 in Tanzania and the worldwide distributed blaCTX‐M‐15‐carrying IncF‐type plasmids). International trade of poultry meat seems to have contributed to the spread of other ESBL variants, such as CTX‐M‐14, and clones. Furthermore, first descriptions of OXA‐48‐ and OXA‐181‐producing E. coli have been recently documented in cattle from Egypt, and the emergent plasmid‐mediated colistin resistance mcr‐1 gene has been also identified in chickens from Algeria, Tunisia and South Africa. These data reflect the urgent need of a larger regulation in the use of veterinary drugs and the implementation of surveillance programmes in order to decelerate the advance of antimicrobial resistance in this continent.
This study aimed to investigate the molecular mechanisms of carbapenem and colistin resistance in K. pneumoniae and E. coli isolates obtained from hospitalized patients in Carthagene International ...Hospital of Tunis. A total of 25 K. pneumoniae and 2 E. coli clinical isolates with reduced susceptibility to carbapenems were recovered. Susceptibility testing and phenotypic screening tests were carried out. ESBL, AmpC, carbapenemase and other antibiotic resistance genes were sought by PCR‐sequencing. The presence of plasmid‐mediated colistin resistance genes (mcr‐1‐8) was examined by PCR and the nucleotide sequence of the mgrB gene was determined. The analysis of plasmid content was performed by PCR‐Based Replicon Typing (PBRT). The clonality of isolates was assessed by PFGE and multilocus sequence typing (MLST). All of the isolates produced carbapenemase activity. They showed a great variation in the distribution of ESBL, AmpC, carbapenemase and other plasmid‐mediated resistance determinants. K. pneumoniae isolates carried blaNDM‐1 (n = 11), blaOXA‐48 (n = 11), blaNDM‐1 + blaOXA‐48 (n = 1), blaNDM‐1 + blaVIM‐1 (n = 1), blaOXA‐204 (n = 1), along with blaCTX‐M, blaOXA, blaTEM, blaCMY, blaDHA and blaSHV genes variants on conjugative plasmid of IncL/M, IncR, IncFIIK, IncFIB, and IncHI1 types. Three sequence types ST101, ST307 and ST15 were identified. The mgrB alteration g109a (G37S) was detected in a single colistin‐resistant, NDM‐1 and OXA‐48‐coproducing K. pneumoniae isolate. The two E. coli isolates belonged to ST95, co‐produced NDM‐1 and CTX‐M‐15, and harboured plasmid of IncFII and IncFIB types. To our knowledge, this is the first report in Tunisia of NDM‐1, OXA‐48, and CTX‐M‐15 coexistence in colistin‐resistant K. pneumoniae ST15.
Significance and Impact of the Study: Our data revealed multiple co‐expressed resistance determinants, including genes encoding carbapenemases, ESBLs, pAmpCs and non‐β‐Lactam resistance in all carbapenem resistance strains investigated. In the present study, we reported a high prevalence of bla NDM‐1 among K. pneumoniae from Carthagene International Hospital of Tunis, mostly related to imported cases. These data urge for screening of patients coming abroad and strict contact isolation measures to stop the further spread in hospital settings.
The objective of this investigation was to analyse the carriage rate of extended-spectrum beta-lactamase (ESBL)-producing
Escherichia coli
in faecal samples of healthy humans in Tunisia and to ...characterise the recovered isolates. One hundred and fifty samples were inoculated on MacConkey agar plates supplemented with cefotaxime (2 μg/ml) for ESBL-positive
E. coli
recovery. The characterisation of ESBL genes and their genetic environments, detection of associated resistance genes, multilocus sequence typing (MLST) and phylogroup typing were performed by polymerase chain reaction (PCR) and sequencing. The presence and characterisation of integrons and virulence factors were studied by PCR and sequencing. ESBL-positive
E. coli
isolates were detected in 11 of 150 faecal samples (7.3%) and one isolate/sample was further characterised. These isolates contained the
bla
CTX-M-1
(ten isolates) and
bla
TEM-52c
genes (one isolate). The IS
Ecp1
(truncated by IS
10
in four strains) and
orf477
sequences were found upstream and downstream, respectively, of all
bla
CTX-M-1
genes. Seven different sequence types (STs) and three phylogroups were identified among CTX-M-1-producing isolates ST/phylogroup (number of isolates): ST58/B1 (3), ST57/D (2), ST165/A (1), ST155/B1 (1), ST10/A (1), ST398/A (1) and ST48/B1 (1). The TEM-52-producing isolate was typed as ST219 and phylogroup B2. Six ESBL isolates contained class 1 integrons with the gene cassettes
dfrA17-aadA5
(five isolates) and
dfrA1-aadA1
(one). Healthy humans in the studied country could be a reservoir of CTX-M-1-producing
E. coli
.
Summary
Reasons for performing study
Staphylococcus intermedius group (SIG) bacteria can colonise the nares of some animals but are also emerging pathogens in humans and animals.
Objectives
To ...analyse SIG nasal carriage in healthy donkeys destined for food consumption in Tunisia and to characterise recovered isolates.
Methods
Nasal swabs from 100 healthy donkeys were tested for SIG recovery, and isolates were identified by biochemical and molecular methods. Antimicrobial susceptibility of isolates was tested and detection of antimicrobial resistance and virulence genes was performed. Isolates were typed at the clonal level by multilocus sequence typing and SmaI pulsed‐field gel electrophoresis.
Results
Staphylococcus delphini and Staphylococcus pseudintermedius (included in SIG) were obtained in 19% and 2% of the tested samples, respectively, and one isolate per sample was characterised. All isolates were meticillin susceptible and mecA negative. Most S. delphini and S. pseudintermedius isolates showed susceptibility to all antimicrobials tested, with the exception of 2 isolates resistant to tetracycline (tet(M) gene) or fusidic acid. The following toxin genes were identified (percentage of isolates): lukS‐I (100%), lukF‐I (9.5%), siet (100%), se‐int (90%), seccanine (19%) and expA (9.5%). Thirteen different pulsed‐field gel electrophoresis profiles were identified among the 21 SIG isolates. Additionally, the following 9 different sequence types (STs) were detected by multilocus sequence typing, 6 of them new: ST219 (6 isolates), ST12 (5 isolates), ST220 (3 isolates), ST13, ST50, ST193, ST196, ST218 and ST221 (one isolate each).
Conclusions
Staphylococcus delphini and S. pseudintermedius are common nasal colonisers of donkeys, generally susceptible to the antimicrobials tested; nevertheless, these SIG isolates contain virulence genes, including the recently described exfoliative gene (expA) and several enterotoxin genes, with potential implications for public health. This is the first description of S. delphini in Tunisia.
The Summary is available in Chinese – see Supporting information.
Phenotypic and genotypic determination of virulence factors were carried out in 46 high-level gentamicin-resistant (HLGR) clinical Enterococcus faecalis (n = 34) and Enterococcus faecium (n = 12) ...isolates recovered from different patients in La Rabta Hospital in Tunis, Tunisia, between 2000 and 2003 (all these isolates harboured the aac(6′)–aph(2″) gene). The genes encoding virulence factors (agg, gelE, ace, cylLLS, esp, cpd, and fsrB) were analysed by PCR and sequencing. The production of gelatinase and hemolysin, the adherence to caco-2 and hep-2 cells, and the capacity for biofilm formation were investigated in all 46 HLGR enterococci. The percentages of E. faecalis isolates harbouring virulence genes were as follows: gelE, cpd, and ace (100%); fsrB (62%); agg (56%); cylLLS (41.2%); and esp (26.5%). The only virulence gene detected among the 12 HLGR E. faecium isolates was esp (58%). Gelatinase activity was detected in 22 of the 34 E. faecalis isolates (65%, most of them with the gelE⁺–fsrB⁺ genotype); the remaining 12 isolates were gelatinase-negative (with the gelE⁺–fsrB– genotype and the deletion of a 23.9 kb fragment of the fsr locus). Overall, 64% of the cylLLS-containing E. faecalis isolates showed β-hemolysis. A high proportion of our HLGR E. faecalis isolates, in contrast to E. faecium, showed moderate or strong biofilm formation or adherence to caco-2 and hep-2 cells.
Nasal swabs of 423 healthy humans who showed different levels of contact with animals (frequent, 168; sporadic, 94; no contact, 161) were obtained in Tunisia (2008-2009), and 99 of them presented ...other associated risk factors. Methicillin-resistant Staphylococcus aureus (MRSA) was detected in one of these 423 samples (0.24%), retrieved from a veterinarian. The MRSA isolate was mecA-positive, typed as ST80-t203-SCCmecIVc-agrIII, and contained tet(K), ant(6)-Ia, and aph(3′)-IIIa genes encoding tetracycline, streptomycin, and kanamycin resistance, respectively. This MRSA isolate also contained the lukF/lukS virulence gene encoding Panton-Valentine leukocidin. Fifty-four (12.8%) additional nasal samples contained methicillin-susceptible S. aureus (MSSA) and one isolate/sample was characterized. A high diversity of spa types (n = 43; 4 new) and pulsed-field gel electrophoresis (PFGE) types (n = 37) was detected among the 55 recovered S. aureus strains. The percentages of antimicrobial resistance/detected resistance genes were as follows: tetracycline 22%/tet(K)-tet(L)-tet(M), erythromycin 5%/msrA, ciprofloxacin 14.5%, trimethoprim-sulfamethoxazole 2%/dfrA, streptomycin 11%/ant(6)-Ia, kanamycin 7%/aph(3′)-IIIa, amikacin 5%, and chloramphenicol 2%. Four and two isolates carried the lukF/lukS and eta and/or etb genes, respectively, and always in individuals with contact with animals. Eleven isolates carried the tst gene and were recovered from individuals with different levels of contact with animals.
Aims: Detection and identification of new antagonistic activities towards Bacillus cereus and relatives.
Methods and Results: Twenty Bacillus thuringiensis strains were screened for their capacity to ...express bacteriocin‐like agents. Strain BMG1.7, isolated from soil, showed an antagonistic activity called thuricin 7. Thuricin 7 was active against several species of the genus Bacillus, including three of the four known B. thuringiensis/B. cereus bacteriocin producers, as well as against Streptococcus pyogenes and Listeria monocytogenes strains. Antimicrobial activity was lost after treatment with proteinase K. The active protein had an apparent molecular weight of 11·6 kDa, and was secreted at the end of the exponential growth phase. Thuricin 7 retained 55% of the activity after incubation at 98°C for 30 min. The mode of action of thuricin 7 was shown to be bactericidal and bacteriolytic.
Conclusions: Thuricin 7 is a novel bacteriocin produced by a newly isolated Bacillus thuringiensis strain BMG1.7.
Significance and Impact of the Study: The characteristics of thuricin 7 indicate that it is a new bacteriocin which may have interesting biotechnological applications due to its relatively large activity spectrum.
Beta-lactamase characterization was carried out in a collection of 18 extended-spectrum beta-lactamase (ESBL)-positive Escherichia Coli isolates from blood (n=8) and urine (n=10) obtained in 2007 in ...a tunisian Hospital. All isolates were clonally unrelated according to PFGE analysis. Seventeen strains presented the bla
CTX-M-15
gene associated with bla
OXA-1
and four of these strains with the blatem-1b gene. The remaining ESBL-positive strain contained the bla
CTX-m-9
gene associated with the bla
OXA-1
and bla
TEM-1b
genes. The orf477 sequence was identified downstream of the bla
CTX-M-15
gene in all 17 bla
CTX-M-15
-positive strains, and ISE
cp
1 upstream in 15 of them (in eight cases truncated by IS26). The presence of a class 1 integron was demonstrated in 4 of the 18 ESBL-positive strains (22.2%), with dfrA17 + aadA5 (3 strains) and dfrA12 + orfF + aadA2 (1 strain) being the gene cassettes identified. The variant aac(6')-Ib-cr was found in 15 bla
CTX-M-15
-containing strains. All 18 ESBL-positive strains were typed as phylogroup b2 and contained at least three of the eight tested virulence genes (fimA, papGIII, hlyA, cnf1, papC, aer, eae and bfp). Six bla
CTX-M-15
-positive strains were included in the serotype O25b and one of them was typed as ST131. Another bla
CTX-M-15
-positive strain serotype-O25 was typed as ST638. The bla
CTX-M-15
, aac(6')-Ib-cr, and aac(3)-II genes were co-transferred by conjugation from 7 donor strains to E. coli CSH26 recipient strain. The bla
CTX-M-15
gene is prevalent among ESBL-positive E. coli strains in the studied hospital, that is frequently found together with aac(6')-Ib-cr, and aac(3)-II genes. The detection of the clone O25b-ST131 in a bla
CTX-M-15
strain corroborates its worldwide dissemination.
Le profil étiologique microbien des infections respiratoires basses (IRB) communautaires de l’enfant a été peu étudié en Tunisie. Une étude prospective a été menée à Sfax entre janvier 2009 et mars ...2010 sur 368 enfants hospitalisés pour pneumonie (n = 78) ou bronchiolite aiguë (n = 290). Les aspirations nasopharyngées ont été analysées par immunofluorescence et par PCR à la recherche des virus influenza, virus para-influenza, virus respiratoire syncytial (VRS), métapneumovirus, rhinovirus, entérovirus, adénovirus, coronavirus, Mycoplasma pneumoniae (Mpn) et Chlamydia pneumoniae (Cpn). Une étiologie ou plus a été retrouvée dans 319 cas (86,7 %) : principalement le VRS (42,7 %), des rhinovirus (32,9 %) et des adénovirus (28,5 %). Dans 40 % des prélèvements positifs, deux ou trois agents pathogènes ont été codétectés. Cette étude a permis de montrer la prévalence élevée des virus dans les IRB de l’enfant dans la région de Sfax et leur détection fréquente en co-infection posant la question sur leur rôle pathogène réel.
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