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.
Heat and mass transfer in many systems are widely accomplished applying natural convection process due to their low cost, reliability, and easy support. Typical applications include different ...mechanisms in various fields such as (solar energy, solar distiller, stream cooling, etc…). Numerical results of turbulent natural convection and mass transfer in an open enclosure for different aspect ratios (AR = 0.5, 1, and 2) with a humid-air are carried out. Mass fraction and local Nusselt number were proposed to investigate the heat and mass transfer. A heat flux boundary conditions were subjected to the lateral walls and the bottom one make as an adiabatic wall, while the top area was proposed as a free surface. Effect of Rayleigh numbers (106≤???≤108) on natural convection and mass flow behavior are analyzed. The governing equations are solved using CFD Fluent code based on the SIMPLE algorithm. The results showed that the cavity with an aspect ratio of AR = 2 has a significant enhancement to raise the rates of both heat and mass transfer. When the Rayleigh number increases, maximum heat transfer rates were observed due to the fluid flow becomes more vigorous. However, mass transfer improves as the Rayleigh number decreases.
Background Carbapenemase-producing Enterobacteriaceae (CPE) are becoming of immediate concern for infection control policies. Prompt detection of CPE on health care setting admission is crucial to ...halt the spread of an outbreak. We report a cluster of 13 Klebsiella pneumoniae carbapenemase (KPC)-2–producing K pneumoniae cases in a tertiary care hospital.The objective of this study was to identify contributing factors originating the outbreak. Methods An outbreak investigation was conducted using descriptive epidemiology, observation of health care practices, and interviews of management staff. A root cause analysis was performed to identify patent and latent failures of infection control measures using the association of litigation and risk management method. Results The main patent failure was the delay in identifying KPC-2–producing K pneumoniae carriers. Contributing factors were work and environmental factors: understaffing, lack of predefined protocols, staff members' characteristics, and underlying patients' characteristics. Latent failures were as follows: no promotion of the national guidelines for prevention of CPE transmission, no clear procedure for the management of patients hospitalized abroad, no clear initiative for promoting a culture of quality in the hospital, biologic activity recently outsourced to a private laboratory, and poor communication among hospital members. Conclusion Clinical management should be better promoted to control hospital outbreaks and should include team work and safety culture.
Abstract The Check-MDR Carba test (Check-Points, Wageningen, Netherlands), which is based on specific molecular recognition of blaNDM , blaKPC , blaOXA-48 , blaVIM , and blaIMP genes by DNA probe ...ligation and real-time PCR detection, was evaluated on 183 well-characterized Gram-negative rods. Representatives of the 5 gene families were accurately identified (specificities and sensitivities of 100%) within 4.5 hours. This test may be helpful to differentiate carbapenem resistance mediated by carbapenemases from those involving other mechanisms.
Klebsiella oxytoca is a member of the family of Enterobacteriaceae and often contains the β-lactamase blaOXY gene. Although this β-lactamase does not naturally hydrolyse ceftazidime, this study ...describes possible in vivo selection of a clinical K. oxytoca isolate showing increased MICs of ceftazidime.
To reveal the molecular mechanism underlying this unusual resistance phenotype, WGS, cloning, overexpression, MIC and steady-state kinetic studies were performed.
A patient was treated for a septic episode with ceftazidime (4 g/day). This therapy was based on earlier culture results in which, amongst others, a K. oxytoca (Velp-1) isolate was identified. After 11 days of treatment, K. oxytoca Velp-2 was isolated from a pus sample drained from the wound. The isolate showed increased resistance to ceftazidime (MIC ≥64 mg/L) compared with the original K. oxytoca isolate (Velp-1). WGS revealed the presence of a novel blaOXY-2 allele, designated blaOXY-2-15, with a two amino acid deletion at Ambler positions 168 and 169 compared with OXY-2-2. Cloning blaOXY-2-15 into Escherichia coli TOP10 resulted in increased MICs of ceftazidime, but reduced MICs of most other β-lactams compared with OXY-2-2. Steady-state kinetics confirmed the results of the MIC data, showing clearly significant ceftazidime hydrolysis.
This report shows the risk of in vivo selection of ceftazidime-resistant K. oxytoca isolates after prolonged ceftazidime treatment. Furthermore, it is the first known report of a K. oxytoca isolate conferring resistance to ceftazidime by a two amino acid deletion in the omega loop of OXY-2-2.
sspecies are the most significant foodborne pathogen in infant milk formula (IMF). These pathogens have been incriminated in severe forms of neonatal meningitis, sepsis, and necrotizing enterocolitis ...with a high mortality rate.
This study was performed to elucidate the effect of heat stress on
spp. (
and
) in reconstituted IMF (RIMF).
The reconstituted formula was inoculated with five
isolates and four
isolates separately. The nine isolates of
spp. were heated in RIMF at 48°C, 52°C, 56°C, 60°C, 64°C, and 66°C. The
- and
-values were determined by using linear regression analysis.
The
-values of all isolates of
(CS1, CS3, CS4, CS5, and CS6) at 48°C, 52°C, 56°C, 60°C, 64°C, and 66°C were in the ranges 7.29-23.47, 2.77-15.50, 0.62-1.04, 0.62-1.02, 0.62-1.00, 0.62-1.00 minutes, respectively; while, the
-values extended from 2.50°C to 4.28°C. The
- values of
isolates (CP1, CP2, CP3, CP4) were in the ranges 7.60-22.32, 1.42-8.45, 0.62-1.08, 0.62-0.78, 0.62-0.78, 0.62-0.79 minutes at 48°C, 52°C, 56°C, 60°C, 64°C, 66°C, respectively and the calculated
-values ranged from 3.33°C to 4.89°C.
This study may contribute to improving the understanding of the behavior of
and
isolates in RIMF at various heat stress temperatures and may participate in the effective control of these pathogens in infant food production.
Background and Aim: Foodborne illnesses are a serious challenge to human health and the economic sector. For example, salmonellosis remains a burden in developed and developing nations. Rapid and ...reliable molecular methods to identify Salmonella strains are essential for minimizing human infection. This study aimed to identify Salmonella spp. in raw milk and dairy products using conventional and molecular techniques and to test the antibiotic susceptibility of the isolated strains.
Materials and Methods: One hundred and thirty-one milk and dairy product samples were randomly collected from different localities in Libya. Samples were examined for the presence of Salmonella by conventional culture techniques, including cultivation in Rappaport-Vassiliadis broth and streaking on xylose lysine deoxycholate agar. Identification also used polymerase chain reaction and partial sequencing of 16S rDNA. Twenty-four antibiotics were used for the examination of antimicrobial resistance of Salmonella spp. isolates with the agar disk diffusion method (Kirby–Bauer technique). Multi-antibiotic resistance index and antibiotic resistance index (ARI)for Salmonella enterica isolates were calculated.
Results: Twenty-one of 131 samples (16%) were positive for Salmonella spp. recovered from 9 (16%), 2 (11%), 4 (22.2%), and 6 (46%) samples of raw cow milk, fermented raw milk, and fresh locally made soft cheeses, Maasora and Ricotta), respectively. Samples of ice cream, milk powder, and infant formula showed no Salmonella spp. contamination. Only 9 of 21 (42.8%) isolates were confirmed as S. enterica by partial sequence 16S rDNA analysis. All isolates were resistant to amoxycillin, bacitracin, penicillin G, lincomycin, vancomycin, clindamycin, and cloxacillin with an ARI of 0.042. In contrast, all tested strains were sensitive to levofloxacin, doxycycline, and ciprofloxacin. In addition, all of the tested isolates (100%) were resistant to more than one antibiotic.
Conclusion: This study demonstrated the applicability of molecular techniques, compared with conventional methods, as preferable for the identification of Salmonella in milk and dairy products and thus reduction of milk-borne transmission to the consumers. From the view of public health, isolation and identification of Salmonella multidrug-resistant strains from raw cow's milk and locally prepared dairy products sold in the Libyan markets indicate the need to improve the handling and processing of milk and dairy products to minimize the prevalence of Salmonella, one of the most important foodborne microorganisms that cause food poisoning.
The aim of the current investigation was to screen the presence of
spp., especially
in meat, meat products of different animal species, and some seafood sold in some retail markets in Libya using ...cultural and molecular techniques, and to study their antibiotics resistance profiles.
A total of 139 samples from red meat, meat products, and seafood were collected from many areas in Libya. Enumeration and isolation of
spp. and
by normal cultural methods followed by molecular identification using molecular techniques by bacterial DNA extraction and partial sequencing of 16S rDNA.
Out of 139 samples, 112 (80.6%) were contaminated with different species of
based on cultural characteristics of
on Baird-Parker medium, for which
was detected in only 32 samples (23%). However, only six out of 18 (33.3%) isolates sent for sequencing were confirmed to be
using the molecular technique. The six identified isolates of
were tested for antimicrobial resistance against 24 most commonly used antibiotics. All isolates were resistant to only two antibiotics (cefotaxime and clindamycin). Among these six isolates, only one confirmed to be
.
Results of this study suggest that food of animal origin could be a source of
with antimicrobial resistance characteristics that can be spread through the food chain, and raise the importance of these results for public health.
Objectives International adoption from developing countries has become an increasing phenomenon in recent years. Given the high prevalence of multidrug-resistant (MDR) bacteria in these countries, ...the adopted children represent a group at risk for both carriage and infection with MDR bacteria. The dynamics of intrafamilial transmission of MDR bacteria after adoption was studied in a prospective study from January 2002 to January 2005. Methods Stool samples, taken at the first visit to the outpatient adoption practice and subsequently every month, from the adopted children of an orphanage of Bamako (Mali) and from all the members of their adoptive families were screened for MDR bacteria and bacterial pathogens. Bacteria were characterized by standard biochemical methods, disc diffusion antibiograms, PFGE and plasmid analysis. β-Lactamase genes were sought by PCR. Results Over the study period, 52 ESBL-producing Enterobacteriaceae (E-ESBL), with Escherichia coli (56%) being the most prevalent, were isolated from 24/25 adoptees at arrival in France. During follow-up, the transmission of ESBL-producing E. coli and Salmonella enterica Babelsberg between the adoptees and their adoptive family members has clearly been demonstrated for 5/22 families (23%). The mean duration of the carriage for the adopted children was 9 months (1–15 months). CTX-M-15 was the most prevalent resistance gene among the E-ESBLs (93%), while SHV-12 was found among the S. enterica Babelsberg studied. Conclusions International travellers, transfer of patients and now adoption may contribute to the global emergence of MDR bacteria. Thus, in addition to the usual screening of adopted children for infectious diseases, additional screening for MDR bacteria should be recommended, at least for children coming from countries with a high prevalence of MDR bacteria.
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