Mirabilis Isolates Research Articles

A novel type 1/2 hybrid IncC plasmid carrying fifteen antimicrobial resistance genes recovered from Proteus mirabilis in China

IncC plasmids are of great concern as vehicles of broad-spectrum cephalosporins and carbapenems resistance genes blaCMY and blaNDM. The aim of this study was to sequence and characterize a multidrug resistance (MDR) IncC plasmid (pPm14C18) recovered from Proteus mirabilis. pPm14C18 was identified in a CMY-2-producing P. mirabilis isolate from chicken in China in 2014, and could be transferred to Escherichia coli conferring an MDR phenotype. Whole genome sequencing confirmed pPm14C18 was a novel type 1/2 hybrid IncC plasmid 165,992bp in size, containing fifteen antimicrobial resistance genes. It harboured a novel MDR mosaic region comprised of a hybrid Tn21tnp-pDUmer, in which blaCTX-M-65, dfrA32 and ereA were firstly reported in IncC plasmid. Phylogenetic relationship reconstruction based on the nucleotide sequences of the 52 IncC backbones showed all type 1 IncC plasmids were clustered into one clade, and then merged with pPm14C18 and finally with the type 2 IncC plasmids and another type 1/2 hybrid IncC plasmid pYR1. The MDR IncC plasmids in P. mirabilis of animal origin might threaten public health, which should be drawn more attention.

Genetic characteristic of class 1 integrons in proteus mirabilis isolates from urine samples.

Background: Proteus mirabilis is an opportunistic pathogen, commonly associated with complicated urinary tract infections (UTIs). UTIs caused by multidrug-resistant Proteus mirabilis have increased worldwide. Multidrug-resistance of Gram-negative enteric bacteria is usually associated with class 1 integrons.Purposes: To investigate the prevalence and characterize gene cassettes of class 1 integrons in multidrug-resistant P. mirabilis Methods: From 2006 to 2008, 314 P. mirabilis isolates from urine were collected from a regional teaching hospital. Antimicrobial resistance of the isolates was determined by disk diffusion methods. The phenotypic confirmatory test of extended-spectrum β-lactamase (ESBL) production was performed as described in the Clinical and Laboratory Standards Institute (CLSI) guideline. The genetic organization of the class 1 integron cassettes was investigated by PCR, cloning, and sequencing of the regions surrounding these genes.Results: Seventy-nine (25%, 79/314) P. mirabilis isolates were ESBL-producing and most ESBL-producing P. mirabilis were positive for blaCTX-M. Class 1 integrons were presented in 76 isolates (24.2%, 76/314), and were more frequently found in ESBL-positive (55/79, 70%) than ESBL-negative (21/235, 8.9%) P. mirabilis isolates. The most prevalence of the cassettes encoded resistance genes were aminoglycoside (aac(6’)-Ib, aacA7, aadAl, aadA2, and aadAla), trimethoprim (dfrAl and dfrA12) and chloramphenicol (catB3 and cmlA6). The most prevalent cassette of dfr12-orfF-aadA2 was found in 49 isolates. The cassette array aadB-catB3-oxa10-aadA1 was first found in P. mirabilis. The enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting patterns were detected in these 76 integron positive P. mirabilis isolates and belonged to 8 profiles.Conclusion: This study investigated the prevalence and characterized gene cassettes of class 1 integrons in MDR P. mirabilis isolates from urine samples. The frequency of gene cassettes in P. mirabilis were partially by clonal spread of the carriers and the results could provide information for effective antimicrobial therapy and infection control.

The impact of production of extended-spectrum \u03b2-lactamases on the 28-day mortality rate of patients with Proteus mirabilis bacteremia in Korea

BackgroundThe incidence of Proteus mirabilis antimicrobial resistance, especially that mediated by extended-spectrum β-lactamases (ESBLs), has increased. We investigated the impact of ESBL production on the mortality of patients with P. mirabilis bacteremia in Korea.MethodsPatients diagnosed with P. mirabilis bacteremia between November 2005 and December 2013 at a 2000-bed tertiary care center in South Korea were included in this study. Phenotypic and molecular analyses were performed to assess ESBL expression. Characteristics and treatment outcomes were investigated among ESBL-producing and non-ESBL-producing P. mirabilis bacteremia groups. A multivariate analysis of 28-day mortality rates was performed to evaluate the independent impact of ESBLs.ResultsAmong 62 P. mirabilis isolates from 62 patients, 14 expressed ESBLs (CTX-M, 2; TEM, 5; both, 6; other, 1), and the 28-day mortality rate of the 62 patients was 17.74%. No clinical factor was significantly associated with ESBL production. The 28-day mortality rate in the ESBL-producing group was significantly higher than that in the non-ESBL-producing group (50% vs. 8.3%, p = 0.001). A multivariate analysis showed that ESBL production (odds ratio [OR], 11.53, 95% confidence interval [CI], 2.11–63.05, p = 0.005) was independently associated with the 28-day mortality rate in patients with P. mirabilis bacteremia.ConclusionsESBL production is significantly associated with mortality in patients with bacteremia caused by P. mirabilis. Rapid detection of ESBL expression and prompt appropriate antimicrobial therapy are required to reduce mortality caused by P. mirabilis bacteremia.

Chromosomal location of the fosA3 and blaCTX-M genes in Proteus mirabilis and clonal spread of Escherichia coli ST117 carrying fosA3-positive IncHI2/ST3 or F2:A-:B- plasmids in a chicken farm

The aim of this study was to investigate the spread and location of the fosA3 gene among Enterobacteriaceae from diseased broiler chickens. Twenty-nine Escherichia coli and seven Proteus mirabilis isolates recovered from one chicken farm were screened for the presence of plasmid-mediated fosfomycin resistance genes by PCR. The clonal relatedness of fosA3-positive isolates, the transferability and location of fosA3, and the genetic context of the fosA3 gene were determined. Seven P. mirabilis isolates with three different pulsed-field gel electrophoresis (PFGE) patterns and five E. coli isolates belonging to sequence type 117 (ST117) and phylogenetic group D were positive for fosA3 and all carried the blaCTX-M gene. In E. coli, the genetic structures IS26–ISEcp1–blaCTX-M-65–IS26–fosA3–1758 bp–IS26 and IS26–ISEcp1–blaCTX-M-3–blaTEM-1–IS26–fosA3–1758 bp–IS26 were present on transferable IncHI2/ST3 and F2:A-:B- plasmids, respectively. However, fosA3 was located on the chromosome of the seven P. mirabilis isolates. IS26–ISEcp1-blaCTX-M-65–IS26–fosA3–1758 bp–IS26 and IS26–blaCTX-M-14–611 bp–fosA3–1222 bp–IS26 were detected in three and four P. mirabilis isolates, respectively. Minicircles that contained both fosA3 and blaCTX-M-65 were shared between E. coli and P. mirabilis. This is the first report of the fosA3 gene integrated into the chromosome of P. mirabilis isolates with the blaCTX-M gene. The emergence and clonal spread of avian pathogenic E. coli ST117 with the feature of multidrug resistance and high virulence are a serious problem.

Dissemination of blaOXA-58 in Proteus mirabilis isolates from Germany.

Characterization of Proteus mirabilis isolates harbouring bla OXA-58 with emphasis on the genetic environment of this resistance determinant. Strains of P. mirabilis ( n = 37) isolated from different patients were tested for the presence of bla OXA-58 . The genetic context of bla OXA-58 was determined by WGS of two strains and Sanger sequencing. Clonality of the strains was assessed by PFGE. Susceptibility testing was performed by microdilution according to EUCAST. Four strains isolated in different geographical regions of Germany were positive for bla OXA-58 , and WGS showed that this resistance gene was harboured on a plasmid. Sanger sequencing confirmed the presence of two nearly identical plasmids, 6219 and 6208 bp in size, in all four strains. Upstream of bla OXA-58 an IS Aba 3-like transposase gene was located. The P. mirabilis strains were not clonally related according to PFGE. MICs of meropenem for three of the strains were only just above the EUCAST breakpoint and the Carba NP test was positive for only two of the strains. To our knowledge, this is the first description of bla OXA-58 in the species P. mirabilis . The resistance gene is harboured by almost identical plasmids in strains not clonally related and from different geographical regions. Apart from an IS Aba 3-like transposase gene upstream of bla OXA-58 the genetic context is different from bla OXA-58 harboured on plasmids in the genus Acinetobacter . With MICs of meropenem well below the EUCAST breakpoint or only just above it and equivocal or false negative results from the Carba NP test, bla OXA-58 can be easily overlooked in P. mirabilis .

Characterizations of the Antimicrobial Resistant Determinants in Proteus spp. Isolated from Humans and Chickens in the Chungcheong Province

Recently, antimicrobial resistance of pathogenic bacteria has been increasing due to excessive use of antimicrobial agents in both humans and livestock. PCR amplification and nucleotide sequence analyses were conducted to investigate16S ribosomal RNA methyltransferase (RMTase) genes and integrons in P. mirabilis strains isolated from clinical specimens and chickens in an area of the Chungcheong providence. In addition, clonality analysis of P. mirabilis strains was performed using a repetitive extragenic palindromic sequence-based PCR (REP-PCR) method. Of the total 38 P. mirabilis isolates, 7 (18.4%) strains were isolated from clinical specimens contained in the RMTase genes and showed resistance to amikacin, tobramycin, and gentamicin. A total of 23 (60.5%) isolates carried class 1 integrons, but no isolates in our study harbored class 2 and class 3 integrons. Class 1 integrons detected in our study harbored genes encoding resistance to aminoglycosides (aadA2, aadA5, aadA7, and aacCA5), β-lactams (blaPSE), erythromycin (ereA), lincosamides (linF), and trimethoprim (dfrA12, dfrA17, and dfrA32). We confirmed that the RMTase genes had spread among only the P. mirabilis isolates from clinical specimens, but class 1 integrons had widely disseminated among P. mirabilis isolates from clinical specimens and chickens. In addition, identical REP-PCR banding patterns were evidenced in only P. mirabilis isolates from chickens. Our results suggest the horizontal spreading of P. mirabilis isolates in the chicken farm. To prevent further spreading of antimicrobial resistant genes among P. mirabilis isolates, monitoring and clinical policing will be required.

Hatchery workers' IgG antibody profiles to airborne bacteria.

Occupational exposure to high concentrations of airborne bacteria in poultry production is related to an increased risk of respiratory disorders. However, etiology and in particular microorganisms' potential role in pathogenesis still needs to be elucidated. Thus, detection of specific antibodies against occupational microbial antigens may lead to identification of potentially harmful species. For the purpose of IgG titer determination, indirect immunofluorescence on various bacterial isolates from duck hatchery air was combined with image-based quantification of fluorescence intensity. Moreover, in addition to established assays with pure bacterial cultures, a new approach utilized complex bioaerosol samples for detection of anti-microbial antibodies in human sera by determination of percentages of antibody-bound cells in different serum dilutions. Mean titers in sera from hatchery workers and a non-exposed control group did not display significant differences for most tested isolates and application of comprehensive cluster analysis to entire titer data revealed no structure reflecting workers and controls group. Furthermore, determination of immunoreactivity to the complete microbial community in workplace air displayed similar proportions of antibody-bound cells in both groups. Although no general differences in immunoreaction patterns were observed, mean titers to a Proteus mirabilis isolate and to 3 of 4 distinct Acinetobacter baumannii isolates were higher in the group of hatchery workers than in the reference group indicating a potential applicability as exposure markers. We conclude, despite long term bioaerosol exposure, hatchery workers' IgG antibody profiles to tested antigens did not differ substantially from those of the control group. However, increased workers' titers to A. baumannii and clinical relevance of this species should lead to further investigations regarding potential involvement in pathogenesis of occupational respiratory disorders.

Regional Spread of CTX-M-2-Producing Proteus mirabilis with the Identical Genetic Structure in Japan.

In this study, we analyzed the molecular epidemiology of extended-spectrum β-lactamase (ESBL)-producing Proteus mirabilis isolates collected from the central region of Japan. Between 2005 and 2012, 820 clinical P. mirabilis isolates were obtained from ten acute care hospitals in Japan. We characterized ESBL confirmatory test-positive isolates by sequencing the ESBL genes and their flanking regions, detecting plasmid replicons, and performing pulsed-field gel electrophoresis (PFGE). Ninety-six isolates (12%) were positive according to the ESBL confirmatory test; all these isolates possessed blaCTX-M-2 with the same flanking structure of upstream ΔISEcp1 and a downstream region identical to downstream blaKLUA-1. IncT was the prevalent, and only, replicon found in 63 isolates. PFGE analysis detected eight clusters with more than one isolate, among which three included 56 isolates and six included isolates from multiple hospitals. CTX-M-2-producing P. mirabilis with an identical genetic structure flanking blaCTX-M-2 is dominant in this Japanese region, and there is evidence for the clonal spread of isolates.

The evaluation of phenotyping and molecular resistance to antibiotics in Proteus species isolated from urinary tract infections in Ilam city

Introduction: Resistance of pathogenic organisms to countenance antibiotics has become a worldwide problem with serious consequences on the treatment of infectious diseases. The aim of this study was to evaluate antibiotic resistance and also the detection of transferred antibiotic resistance by plasmid in clinical Proteus isolates. Materials and methods: A total of 250 urine samples were collected from patient suffered from urinary tract infection (UTI), and cultured on blood agar and MacConkey's agar. Positive cultures were diagnosed by routine microbiological and biochemical tests. Antibiotic susceptibility test was performed by disc diffusion method. The minimum inhibitory concentration (MIC) was evaluated by agar dilution method, and also antibiotic resistance mediated by plasmid was determined using transformation of plasmids to plasmid free Escherichia coli ATCC 25922 as competent cell. Results: Among 200 samples, 120 samples (60%) were collected from female and 80 samples (40%) were isolated from males. Out of 25 species (12.5%) were diagnosed as Proteus. Al isolates were resistant to ampicillin (maximum frequency), only 16% of isolates were resistance to amikacin (minimum resistance). Totally, 66.66% of Proteus isolates harbored plasmids. All plasmid containing P. mirabilis isolates were able to transferred resistance to amoxicillin, ampicillin, while rate of resistance to other antibiotics were as amikacin (88%), gentamycin (72%), tetracycline (50%), tobramycin (48%), ceftazidime, cefotaxime (32%) and ciprofloxacin (22%). Conclusion: Widespread use of antibiotics cause to spread or emerge antibiotic resistances among bacteria by R–plasmids transfer.

Emergence of multidrug-resistant Proteus mirabilis in along-term care facility in Croatia.

An increased frequency of Proteus mirabilis isolates resistant to expanded-spectrum cephalosporins was observed recently in along-term care facility in Zagreb (Godan). The aim of this study was the molecular characterization of resistance mechanisms to new cephalosporins in P.mirabilis isolates from this nursing home. Thirty-eight isolates collected from 2013-2015 showing reduced susceptibility to ceftazidime were investigated. Antibiotic susceptibilities were determined by broth microdilution method. Inhibitor-based tests were performed to detect extended-spectrum (ESBLs) and AmpC β-lactamases. AmpC β-lactamases were characterized by polymerase chain reaction (PCR) followed by sequencing of bla ampC genes. Quinolone resistance determinants (qnr genes) were characterized by PCR. Genotyping of the isolates was performed by repetitive element sequence (rep)-PCR and pulsed-field gel electrophoresis (PFGE). Presence of an AmpC β-lactamase was confirmed in all isolates by combined-disk test with phenylboronic acid. All isolates were resistant to amoxicillin alone and combined with clavulanate, cefotaxime, ceftriaxone, cefoxitin, and ciprofloxacin; but susceptible to cefepime, imipenem, and meropenem. PCR followed by sequencing using primers targeting bla ampc genes revealed CMY-16 β-lactamase in all but one strain. Bla cmy-16 was carried by anon-conjugative plasmid which did not belong to any known plasmid-based replicon typing (PBRT) group. Rep-PCR identified one large clone consisting of 15isolates, three pairs or related isolates, one triplet, and four singletons. PFGE confirmed the clonality of the isolates. This is the first report of multidrug resistant P.mirabilis in anursing home in Croatia. Cephalosporin resistance was due to plasmid-mediated AmpC β-lactamase CMY-16.

Antimicrobial Resistance and <i>β</i>-Lactamase Production among Hospital Dumpsite Isolates

Metallo-β-Lactamases (MBLs) and Extended Spectrum β-Lactamses (ESBLs) have emerged world-wide as a significant source of β-lactam resistance. The emergence of MBLs and ESBLs encoded on plasmids among Gram-negative pathogens in hospital dumpsites was investigated. Soils of different government and private hospitals were collected and processed following standard bacteriological techniques. Antimicrobial susceptibility testing was carried out by the disk-diffusion technique using Ceftazidime (30 μg), Cefuroxime (30 μg), Cefotaxime (30 μg), Cefixime (5 μg), Trimethprim-sulfamethoxazole (25 μg), Gentamycin (100 μg) Amoxicillin-Clavunalate (30 μg), Ciprofloxacin (5 μg), Ofloxacin (5 μg), Nitrofurantoin (300 μg) and Imipenem (10 μg). The role of plasmids in resistance was evaluated by subjecting isolates to curing using Sodium Dodecyl Sulfate (SDS). ESBLs production by Double-Disk Synergy Test (DDST) was carried out. Isolates resistant to Imipenem were subjected to a confirmatory test using Modified Hodge’s test and to MBLs production by DDST. Eighty-two Gram-negative isolates comprising of 32 (39.02%) Escherichia coli, 20 (24.39%) Serratia marcescens, 14 (17.07%) Klebsiella pneumonia, 10 (12.28%) Proteus mirabilis and 6 (7.32%) Enterobacter aerogenes were obtained. Susceptibility results revealed a 100% resistance of all isolates to Ceftazidime, Cefuroxime, Cefixime, Amoxycillin-clavulanate and Cefotaxime. A total of 66 (80.48%) isolates harboured plasmids out of which 26 (31.71%) isolates were ESBL producers. MBLs production was observed in 8 (25.00%) E. coli, 2 (2.41%) Klebsiella pneumonia and 2 (2.41%) Proteus mirabilis isolates. All MBLs producing isolates were ESBLs producers. The finding of highly resistant isolates producing ESBLs and MBLs in a hospital environment is quite disturbing and should be addressed urgently.

Inhibition of swarming behaviour in Proteus mirabilis by Pelargonium graveolens essential oil

Objective: The purpose of the present study was to evaluate the anti-swarming potential of Pelargonium graveolens essential oil against the Proteus isolate. Materials and methods: The effect of sub-minimal inhibitory concentrations of Pelargonium graveolens essential oil and aroma-chemicals was studied on swarming differentiation of urinary Proteus mirabilis isolate. The parameters under study were number of concentric rings and diameter of swarm fronts. Results and Discussion: The concentrations of P. graveolens essential oil ranging from 1.12-8.96 mg/ml showed a pronounced reduction in the diameter of the colony as a function of time. Evident reduction in the number of concentric rings was also observed due to the incorporation of P. graveolens essential oil at 8.96 mg/ml and 4.48 mg/ml concentrations. Conclusion: Hence, the inhibition of swarming by P. graveolens essential oil suggests its potential to be developed as a product for preventing P. mirabilis infections.Bangladesh Journal of Medical Science Vol.14(4) 2015 p.384-388

High Prevalence of SXT/R391-Related Integrative and Conjugative Elements Carrying blaCMY-2 in Proteus mirabilis Isolates from Gulls in the South of France.

The genetic structures involved in the dissemination of blaCMY-2 carried by Proteus mirabilis isolates recovered from different gull species in the South of France were characterized and compared to clinical isolates. blaCMY-2 was identified in P. mirabilis isolates from 27/93 yellow-legged gulls and from 37/65 slender-billed gulls. It was carried by a conjugative SXT/R391-like integrative and conjugative element (ICE) in all avian strains and in 3/7 human strains. Two clinical isolates had the same genetic background as six avian isolates.

Investigating the Portability Bacteria Proteus mirabilis Isolated From Wounds and Burns Infections to Form Swarming and Study the Virulence Factor Genetically.

This study was designed to investigate ability of the bacteria Proteus mirabilis isolated from wounds and burns infections to production of virulence factor swarming and samples elected included the most antibiotic-resistant isolates and by (4) isolates of the bacterium Proteus mirabilis diagnosed depending on the biochemical test as well as the production of the phenomenon swarming. The use of heat as a factor curing of plasmids electric deportation results showed a loss of status in the plasmids isolates were elected as well as the loss in the formation of the phenomenon of isolates swarming referring to plasmids role in the formation of such status.

Identification of emergent bla CMY-2 -carrying Proteus mirabilis lineages by whole-genome sequencing.

Whole-genome sequencing of 24 Proteus mirabilis isolates revealed the clonal expansion of two cefoxitin-resistant strains among patients with community-onset infection. These strains harboured blaCMY-2 within a chromosomally located integrative and conjugative element and exhibited multidrug resistance phenotypes. A predominant strain, identified in 18 patients, also harboured the PGI-1 genomic island and associated resistance genes, accounting for its broader antibiotic resistance profile. The identification of these novel multidrug-resistant strains among community-onset infections suggests that they are endemic to this region and represent emergent P. mirabilis lineages of clinical significance.

The spread of bla OXA-48 and bla OXA-244 carbapenemase genes among Klebsiella pneumoniae, Proteus mirabilis and Enterobacter spp. isolated in Moscow, Russia

BackgroundThe spread of carbapenemase-producing Enterobacteriaceae (CPE) is a great problem of healthcare worldwide. Study of the spread for blaOXA-48-like genes coding epidemically significant carbapenemases among hospital pathogens is important for the regional and global epidemiology of antimicrobial resistance.MethodsAntibacterial resistant isolates of Klebsiella pneumoniae (n = 95) from 54 patients, P.mirabilis (n = 32) from 20 patients, Enterobacter aerogenes (n = 6) from four patients, and Enterobacter cloacae (n = 4) from four patients were collected from January, 2013 to October, 2014 in neurosurgical intensive care unit (ICU) of the Burdenko Neurosurgery Institute, Moscow. Characteristics of the isolates were done using susceptibility tests, PCR detection of the resistance genes, genotyping, conjugation, DNA sequencing, and bioinformatic analysis.ResultsMajor strains under study were multi drug resistant (MDR), resistant to three or more functional classes of drugs simultaneously—98.9 % K. pneumoniae, 100 % P.mirabilis, one E.aerogenes isolate, and one E.cloacae isolate. Molecular-genetic mechanism of MDR in K.pneumoniae and P.mirabilis isolates were based on carrying of epidemic extended-spectrum beta-lactamase blaCTX-M-15 gene (87.2 and 90.6 % accordingly), carbapenemase blaOXA-48-like gene (55.3 and 23.3 % accordingly), and class 1 (54.8 and 31.3 % accordingly) and class 2 (90.6 % P. mirabilis) integrons. The blaOXA-48-like-positive K. pneumoniae were collected during whole two-year surveillance period, while P. mirabilis and Enterobacter spp. carrying blaOXA-48-like genes were detected only after four and 18 months after the research start, respectively. The blaOXA-48-like gene acquisition was shown for P. mirabilis isolates collected from five patients and for E. cloacae isolate collected from one patient during their stay in the ICU, presumably from blaOXA-48-like-positive K. pneumoniae. The source of the blaOXA-244 gene acquired by E. aerogenes isolates and the time of this event were not recognized.ConclusionsThe expanding of CPE in the surveyed ICU was associated with the spread of blaOXA-48 and blaOXA-244 carbapenemase genes documented not only among K.pneumoniae, well-known bacterial host for such genes, but among P.mirabilis, E.aerogenes, and E. cloacae.

English

The aim of the present investigation is to trace the epidemiological relatedness between different isolates of proteus sp. obtained from Dakahleia governorate as compared with similar sources from the adjacent Damietta governorate in Egypt. A total of 500 bacterial isolates were collected from human and animal sources including urine samples, sputum, wound, throat and ear swabs, endotracheal aspirate, breast swab, bile aspirate, blood samples, human and animal stools. From a total of 70 Proteus isolates, 62 were identified as Proteus mirabilis while eight as Proteus vulgaris. All Proteus mirabilis isolates were screened for susceptibility to ten different antimicrobials and were classified into 29 different patterns. Two resistant strains were found to belong to pattern No. 10 (isolates No. 11 and 19). A second pair of isolates namely No. 27&31 was classified into pattern No. 18. A third pair of (isolates No 30 and 16) was found to have great similarity to pattern No. 18 with a minor difference in resistance against one or two antibiotics. For a molecular characterization of the resistance determinants, 15 of the highly resistant Proteus mirabilis isolates were screened for the presence of different classes of integrons. Class 1 was the dominantly detected type that confers resistance to trimethoprim and aminoglycosides. One isolate was found to contain class 2. Similar integron components (dfrA15) could be proved among strains of different human sources (No. 11 & 19). Another similar type of intergon components (dfrA17) -(aadA5) was found in human isolates 31, 27, 30 & 16. In conclusion, three pairs of the studied isolates have been turned out to be epidemiologically related with the possibility of hospital infection and of strain transfer from one governorate to the other. Key words: Proteus, integrons, resistance pattern, swarming.

Ceftazidime-avibactam activity tested against Enterobacteriaceae isolates from U.S. hospitals (2011 to 2013) and characterization of β-lactamase-producing strains.

Ceftazidime-avibactam (MIC50/90, 0.12/0.25 μg/ml) inhibited 99.9% (20,698/20,709) of Enterobacteriaceae isolates at ≤8 μg/ml. This compound was active against resistant subsets, including ceftazidime-nonsusceptible Enterobacter cloacae (MIC50/90, 0.25/0.5 μg/ml) and extended-spectrum β-lactamase (ESBL) phenotype isolates. An ESBL phenotype was noted among 12.4% (1,696/13,692 isolates from targeted species) of the isolates, including 776 Escherichia coli (12.0% for this species; MIC50/90, 0.12/0.25 μg/ml), 721 Klebsiella pneumoniae (16.3%; MIC50/90, 0.12/0.25 μg/ml), 119 Klebsiella oxytoca (10.3%; MIC50/90, 0.06/0.25 μg/ml), and 80 Proteus mirabilis (4.9%; MIC50/90, 0.06/0.12 μg/ml) isolates. The most common enzymes detected among ESBL phenotype isolates from 2013 (n = 743) screened using a microarray-based assay were CTX-M-15-like (n = 307), KPC (n = 120), SHV ESBLs (n = 118), and CTX-M-14-like (n = 110). KPC producers were highly resistant to comparators, and ceftazidime-avibactam (MIC50/90, 0.5/2 μg/ml) and tigecycline (MIC50/90, 0.5/1 μg/ml; 98.3% susceptible) were the most active agents against these strains. Meropenem (MIC50/90, ≤0.06/≤0.06 μg/ml) and ceftazidime-avibactam (MIC50/90, 0.12/0.25 μg/ml) were active against CTX-M-producing isolates. Other enzymes were also observed, and ceftazidime-avibactam displayed good activity against the isolates producing less common enzymes. Among 11 isolates displaying ceftazidime-avibactam MIC values of >8 μg/ml, three were K. pneumoniae strains producing metallo-β-lactamases (all ceftazidime-avibactam MICs, >32 μg/ml), with two NDM-1 producers and one K. pneumoniae strain carrying the bla(KPC-2) and bla(VIM-4) genes. Therapeutic options for isolates producing β-lactamases may be limited, and ceftazidime-avibactam, which displayed good activity against strains, including those producing KPC enzymes, merits further study in infections where such organisms occur.

Occurrence and detection of AmpC β-lactamases among Enterobacteriaceae isolates from patients at Ain Shams University Hospital

BackgroundAmpC β-lactamases are often plasmid mediated that hydrolyze all β-lactam antibiotics except cefepime and carbapenems. Aim of the studyWe aimed to evaluate the presence of AmpC β-lactamase among Enterobacteriaceae isolates separated from patients with nosocomial infections, and to detect the genetic basis for AmpC production in these strains. Subjects and methods50 AmpC β-lactamase Enterobacteriaceae were analyzed for the presence of AmpC production. Three phenotypic AmpC confirmation assays (AmpC E test, the disk approximation test, Amp C EDTA disc) were able to detect the majority of AmpC-positive strains correctly. Molecular detection of plasmid mediated AmpC by multiplex PCR was conducted on them. ResultsThe results show that from the 148 total isolates obtained from ICU admitted patients with suspected nosocomial infections, 50 (33.8%) were AmpC β-lactamase isolates. For the 50 AmpC isolates, all phenotypic Amp C tests gave a positive result. Among these isolates, plasmid encoded AmpC genes were detected by multiplex PCR in 46 (92%) isolates, which included Klebsiella pneumoniae (n=22) (47.8%), Escherichia coli (n=15) (32.6%), and Proteus mirabilis (n=9) (19.6%). One E. coli, one K. pneumoniae, and two P. mirabilis isolates showed no AmpC gene. The most prevalent AmpC gene was that belonging to family CMY-1 which was detected in 73.9% (34/46) of all isolates. ConclusionIt could be concluded that: Amp C producing isolates among Enterobacteriaceae strains have been increasingly recognized in the Ain Shams University Hospital.Thus, molecular identification of the genes encoding AmpC would be essential for a reliable epidemiological investigation of their transmission in hospitals.

Allicin from garlic inhibits the biofilm formation and urease activity of Proteus mirabilis in vitro.

Several virulence factors contribute to the pathogenesis of Proteus mirabilis. This study determined the inhibitory effects of allicin on urease, hemolysin and biofilm of P. mirabilis ATCC 12453 and its antimicrobial activity against 20 clinical isolates of P. mirabilis. Allicin did not inhibit hemolysin, whereas it did inhibit relative urease activity in both pre-lysed (half-maximum inhibitory concentration, IC50 = 4.15 μg) and intact cells (IC50 = 21 μg) in a concentration-dependent manner. Allicin at sub-minimum inhibitory concentrations (2-32 μgmL(-1)) showed no significant effects on the growth of the bacteria (P > 0.05), but it reduced biofilm development in a concentration-dependent manner (P < 0.001). A higher concentration of allicin was needed to inhibit the established biofilms. Using the microdilution technique, the MIC90 and MBC90 values of allicin against P. mirabilis isolates were determined to be 128 and 512 μgmL(-1), respectively. The results suggest that allicin could have clinical applications in controlling P. mirabilis infections.