scieditor/keyword-auto-complete-corpus · Datasets at Hugging Face

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3 7
statistical analysis the results were analyzed using the spss version 16 to obtain frequencies and comparison among clones
non parametric chi square test was used
a p value 0 05 was considered statistically significant
4 1
bacterial isolates totally 124 single patient isolates were recovered
all isolates were positive for blaoxa 51 like and identified as a baumannii
the rate of isolates from each ward and specimen are shown in table 2
abbreviation icu intensive care unit
4 2
antimicrobial susceptibility the results of antimicrobial susceptibility test by disk diffusion method are shown in table 3
colistin and polymyxin b were the most active agents against the tested isolates
according to the results of mics by e test among 124 isolates 97 78 2 were resistant to imipenem
however meropenem resistance was observed in 91 73 4 of the studied isolates
only one isolate 0 8 was resistant to colistin and 123 isolates 98 2 were susceptible to this antibiotic
no tigecycline resistant isolate was observed and 99 79 8 and 25 20 2 isolates were sensitive and intermediate to this antibiotic respectively
abbreviation na not available
avalues are expressed as
4 3
pcr amplification of oxa genes multiplex pcr analysis identified blaoxa 23 like in 83 85 6 of carbapenem resistant isolates
six isolates 6 2 contained blaoxa 24 like figure 1
all isolates were negative for blaoxa 58 like
eight isolates were carbapenem resistant but had only blaoxa 51 like and other studied isolates were negative in the other studied genes
no amplification products were obtained in carbapenem susceptible isolates
agarose gel showing oxas genes obtained by multiplex pcr lanes 1 and 12 100 bp dna ladder lanes 2 3 and 9 isolates with blaoxa 24 like in 249 bp lanes 4 8 isolates with blaoxa 23 like in 501bp lane 10 negative control distilled water
lane 11 positive control acinetobacter baumannii nctc 13304 nctc 13302 and nctc 13305 were used as positive controls for blaoxa 23 like blaoxa 24 like and blaoxa 58 like respectively
4 4
metallo β lactamase e test to study the mbl production carbapenem resistant isolates were evaluated by double disk synergy dds test and e test mbl strips
of the 97 carbapenem resistant isolates 41 42 3 exhibited a 7 mm inhibitory zone and were categorized as mbl producer
however 56 isolates 57 7 were negative for mbl production
results of mbl e test showed that among 97 carbapenem resistant isolates 77 79 4 were positive for metallo β lactamase production and 20 isolates 20 6 were negative figure 2
pcr did not detect metallo β lactamase genes including blavim blaimp and blaspm among the studied isolates
a mbl producer acinetobacter baumannii isolate an inhibitory zone is observed in imipenem edta compared to that of imipenem only
4 5
rep pcr among carbapenem resistant isolates six clones a f were observed which three of them were more prevalent figure 3
genotype a was the most prevalent p value 0 001 and 30 9 30 isolates belonged to this genotype
the prevalence of other genotypes were as follows 28 isolates 28 9 belonged to clone b 26 isolates 26 8 to clone c 10 isolates 10 3 to clone d and 2 isolates 2 1 to clone e clone f contained only one isolate 1
carbapenem susceptible isolates 27 isolates had unique genotypes
an agarose gel rep pcr product for the resistant isolates for each clone double fingerprints are shown
lanes 1 6 and 13 1 kb dna ladder lanes 2 and 3 clone a lanes 4 5 clone b lanes 7 and 8 clone c lane 9 and 10 clone d lane 11 negative control lane 12 a baumannii nctc 12156 atcc 19606
5
discussion in the current study most of the isolates 74 2 were obtained from patients in icus and in accordance to other researches worldwide the rate of infection caused by a baumannii is high in icus 25 26
previously it was reported that a baumannii is more prevalent among endotracheal aspirate samples
moreover ventilator associated pneumonia is one of the frequent nosocomial infections caused by this organism 27 31
in accordance to the mentioned studies most of the current study samples 57 3 were isolated from tracheal aspirates
in the present study antimicrobial susceptibility pattern showed that colistin and polymyxin b are the most effective agents against a baumannii isolates in vitro
colistin is the last line antimicrobial agent to treat multidrug resistant a baumannii 26 32
although colistin resistant isolates are reported globally 32 in the current study only 0 8 of isolates were colistin resistant
this result indicates that colistin can be used to treat a baumannii infections in the studied hospitals
afterwards among the tested antimicrobial agents the highest rate of resistance was observed against rifampin 96 8 and 3 2 of the isolates were resistant and intermediate to this antibiotic respectively
no isolate was sensitive to rifampin hence it is suggested t that rifampin might be ineffective to treat a baumannii infections in the studied hospitals
carbapenems are successfully used to treat multidrug resistant a baumannii infections however in recent years increase of carbapenem resistant a baumannii isolates compromised their use 4 26 33
the emergence of carbapenem resistant a baumannii is a global concern 4
in the current study the rates of resistance to imipenem by e test and disk diffusion method were 78 2 and 74 2 respectively
in addition 79 8 and 73 4 of the isolates were resistant to meropenem by disk diffusion and e test respectively
there is a discrepancy between carbapenems e test and disk diffusion method
based on e test 78 2 of the isolates were resistant to imipenem while disk diffusion method showed that 74 2 of the isolates were resistance to imipenem
in contrast meropenem e test detected 73 4 of isolates as resistant whilst according to disk diffusion more isolates 79 8 were recorded as meropenem resistant
however authors could not elucidate this difference
in a baumannii the most common carbapenemase genes involved in carbapenem resistance are blaoxa 23 like blaoxa 24 like blaoxa 58 like and blaoxa 143 like 26 34
in the current study multiplex pcr detected 85 6 of carbapenem resistant isolates carrying blaoxa 23 like
the spread of oxa genes varies in different parts of the world and blaoxa 23 like is reported from 31 to 94 7 12 35 39
the current study found that 6 2 of carbapenem resistant isolates harbor blaoxa 24 like
some authors worldwide reported the rate of blaoxa 24 like from 0 to 85 43 7 33 36 38 40
the results of the current study were consistent with those of other studies and the findings for blaoxa 23 like and blaoxa 24 like were in the reported ranges
in contrast to other studies that reported the range of blaoxa 58 like from 2 to 84 92 12 35 38 40 the current study could not find any isolates positive for blaoxa 58 like
albeit the reported co existence of oxas genes 29 41 42 coexistence between these genes was not observed in the current study and all a baumannii isolates only had one of the blaoxa 23 like or blaoxa 24 like genes
in the current study 42 3 and 79 4 of the isolates were mbl positive by dds test and mbl e test respectively
despite phenotypic tests no blaimp blavim and blaspm genes were detected by pcr and the isolates were negative for these genes
there are some possibilities about this phenomenon 1 the mbl production may be false positive and due to bactericidal activity of edta which may result in increased inhibitory zone and not associated with true mbl production 43 2 mbl production my be true positive due to other mbl genes such as blandm that were not investigated in the current study 44
similar results are reported that a baumannii isolates were mbl producer by phenotypic tests but no mbl encoding genes were detected 45 46
it is reported that mbl e test has good sensitivity for mbl detection and could detected mbl both chromosomally and plasmid mediated in aerobic and anaerobic bacteria 47
according to the e test results it is possible that the current study isolates were true mbl producers
interestingly the study found eight carbapenem resistant isolates that were negative for blaoxa 23 like blaoxa 24 like blaoxa 58 like and mbl genes and only harbored blaoxa 51 like
similarly nowak et al
reported that seven isolates of carbapenem resistant a baumannii only had blaoxa 51 like 29
carbapenem resistance in these isolates may be associated with other mechanisms such as modification of penicillin binding proteins loss of porins and decreased permeability ampc stable derepression or over expression of efflux pump 4 8 9
it is noteworthy that insertion of isaba1 in upstream of blaoxa 51 like can lead to caebapenem resistance in a baumannii 48
the relationship between harboring blaoxa 51 like and resistance to carbapenem in the eight isolates still need to be investigated
the current study also aimed to investigate the clonality of a baumannii isolates by rep pcr
genotypic comparison by rep pcr revealed that carbapenem resistant isolates belonged to six clones
all clones were spread in the icus
clone a was dominant 30 9 and clone f had the lowest prevalence 1
clonal dissemination of carbapenem resistant a baumannii was previously reported in different studies
it has been establish that multidrug resistant of a baumannii isolates with similar genotype can disseminate among various wards different hospitals and even among cities 4 10 12 49 51
in the current study the vast majority of carbapenem resistant isolates 94 97 96 9 belonged to one of the four dominant genotypes indicating clonal dissemination of resistant isolates in the studied hospitals
in conclusion overall the rate of carbapenem resistant isolates were high in the studied hospitals
colistin and polymyxin b were the effective antimicrobial agents in vitro
since in the current study blaoxa 58 like or mbl genes were not detected it seems that carbapenem resistance is mostly related to blaoxa 23 like and blaoxa 24 like and these genes may play an important role in carbapenem resistance in the isolates
in addition four clones of carbapenem resistant of a baumannii isolates are disseminated in the two studied hospitals and clone a was dominant
in accordance to other studies in the current investigation most of the resistant isolates belonged to four clones indicating clonal dissemination of a baumannii in the studied hospitals and that effective infection control strategies are necessary to control the spread of these resistant isolates
background a diversity of virulence factors work together to create the pathogenicity of staphylococcus aureus
these factors include cell surface components that promote adherence to surfaces as well as exoproteins such as panton valentine leukocidin pvl encoded by the luk pv genes that invade or bypass the immune system and are toxic to the host thereby enhancing the severity of infections caused by methicillin resistant staphylococcus aureus mrsa
objectives the aim of this study was to determine the frequency of pvl positive mrsa strains by real time pcr and their antibiotic susceptibility patterns by phenotypic test
materials and methods in total 284 staphylococcus isolates identified by phenotypic methods from clinical samples of shahrekord university hospitals shahrekord iran were tested for nuc mec a and pvl genes by taqman real time pcr
the antibiotic susceptibility patterns of pvl containing mrsa strains were determined via the disk diffusion method
results in total 196 isolates 69 were nuc positive i e s aureus of those isolates 96 49 were mec a positive mrsa
eighteen 18 8 of the 96 mrsa positive and 3 3 of the 100 methicillin susceptible staphylococcus aureus mssa strains were pvl positive
pvl positive mrsa strains were mostly recovered from tracheal specimens
eight pvl positive mrsa strains were resistant to all the tested antibiotics except vancomycin

3 7

statistical analysis the results were analyzed using the spss version 16 to obtain frequencies and comparison among clones

non parametric chi square test was used

a p value 0 05 was considered statistically significant

4 1

bacterial isolates totally 124 single patient isolates were recovered

all isolates were positive for blaoxa 51 like and identified as a baumannii

the rate of isolates from each ward and specimen are shown in table 2

abbreviation icu intensive care unit

4 2

antimicrobial susceptibility the results of antimicrobial susceptibility test by disk diffusion method are shown in table 3

colistin and polymyxin b were the most active agents against the tested isolates

according to the results of mics by e test among 124 isolates 97 78 2 were resistant to imipenem

however meropenem resistance was observed in 91 73 4 of the studied isolates

only one isolate 0 8 was resistant to colistin and 123 isolates 98 2 were susceptible to this antibiotic

no tigecycline resistant isolate was observed and 99 79 8 and 25 20 2 isolates were sensitive and intermediate to this antibiotic respectively

abbreviation na not available

avalues are expressed as

4 3

pcr amplification of oxa genes multiplex pcr analysis identified blaoxa 23 like in 83 85 6 of carbapenem resistant isolates

six isolates 6 2 contained blaoxa 24 like figure 1

all isolates were negative for blaoxa 58 like

eight isolates were carbapenem resistant but had only blaoxa 51 like and other studied isolates were negative in the other studied genes

no amplification products were obtained in carbapenem susceptible isolates

agarose gel showing oxas genes obtained by multiplex pcr lanes 1 and 12 100 bp dna ladder lanes 2 3 and 9 isolates with blaoxa 24 like in 249 bp lanes 4 8 isolates with blaoxa 23 like in 501bp lane 10 negative control distilled water

lane 11 positive control acinetobacter baumannii nctc 13304 nctc 13302 and nctc 13305 were used as positive controls for blaoxa 23 like blaoxa 24 like and blaoxa 58 like respectively

4 4

metallo β lactamase e test to study the mbl production carbapenem resistant isolates were evaluated by double disk synergy dds test and e test mbl strips

of the 97 carbapenem resistant isolates 41 42 3 exhibited a 7 mm inhibitory zone and were categorized as mbl producer

however 56 isolates 57 7 were negative for mbl production

results of mbl e test showed that among 97 carbapenem resistant isolates 77 79 4 were positive for metallo β lactamase production and 20 isolates 20 6 were negative figure 2

pcr did not detect metallo β lactamase genes including blavim blaimp and blaspm among the studied isolates

a mbl producer acinetobacter baumannii isolate an inhibitory zone is observed in imipenem edta compared to that of imipenem only

4 5

rep pcr among carbapenem resistant isolates six clones a f were observed which three of them were more prevalent figure 3

genotype a was the most prevalent p value 0 001 and 30 9 30 isolates belonged to this genotype

the prevalence of other genotypes were as follows 28 isolates 28 9 belonged to clone b 26 isolates 26 8 to clone c 10 isolates 10 3 to clone d and 2 isolates 2 1 to clone e clone f contained only one isolate 1

carbapenem susceptible isolates 27 isolates had unique genotypes

an agarose gel rep pcr product for the resistant isolates for each clone double fingerprints are shown

lanes 1 6 and 13 1 kb dna ladder lanes 2 and 3 clone a lanes 4 5 clone b lanes 7 and 8 clone c lane 9 and 10 clone d lane 11 negative control lane 12 a baumannii nctc 12156 atcc 19606

5

discussion in the current study most of the isolates 74 2 were obtained from patients in icus and in accordance to other researches worldwide the rate of infection caused by a baumannii is high in icus 25 26

previously it was reported that a baumannii is more prevalent among endotracheal aspirate samples

moreover ventilator associated pneumonia is one of the frequent nosocomial infections caused by this organism 27 31

in accordance to the mentioned studies most of the current study samples 57 3 were isolated from tracheal aspirates

in the present study antimicrobial susceptibility pattern showed that colistin and polymyxin b are the most effective agents against a baumannii isolates in vitro

colistin is the last line antimicrobial agent to treat multidrug resistant a baumannii 26 32

although colistin resistant isolates are reported globally 32 in the current study only 0 8 of isolates were colistin resistant

this result indicates that colistin can be used to treat a baumannii infections in the studied hospitals

afterwards among the tested antimicrobial agents the highest rate of resistance was observed against rifampin 96 8 and 3 2 of the isolates were resistant and intermediate to this antibiotic respectively

no isolate was sensitive to rifampin hence it is suggested t that rifampin might be ineffective to treat a baumannii infections in the studied hospitals

carbapenems are successfully used to treat multidrug resistant a baumannii infections however in recent years increase of carbapenem resistant a baumannii isolates compromised their use 4 26 33

the emergence of carbapenem resistant a baumannii is a global concern 4

in the current study the rates of resistance to imipenem by e test and disk diffusion method were 78 2 and 74 2 respectively

in addition 79 8 and 73 4 of the isolates were resistant to meropenem by disk diffusion and e test respectively

there is a discrepancy between carbapenems e test and disk diffusion method

based on e test 78 2 of the isolates were resistant to imipenem while disk diffusion method showed that 74 2 of the isolates were resistance to imipenem

in contrast meropenem e test detected 73 4 of isolates as resistant whilst according to disk diffusion more isolates 79 8 were recorded as meropenem resistant

however authors could not elucidate this difference

in a baumannii the most common carbapenemase genes involved in carbapenem resistance are blaoxa 23 like blaoxa 24 like blaoxa 58 like and blaoxa 143 like 26 34

in the current study multiplex pcr detected 85 6 of carbapenem resistant isolates carrying blaoxa 23 like

the spread of oxa genes varies in different parts of the world and blaoxa 23 like is reported from 31 to 94 7 12 35 39

the current study found that 6 2 of carbapenem resistant isolates harbor blaoxa 24 like

some authors worldwide reported the rate of blaoxa 24 like from 0 to 85 43 7 33 36 38 40

the results of the current study were consistent with those of other studies and the findings for blaoxa 23 like and blaoxa 24 like were in the reported ranges

in contrast to other studies that reported the range of blaoxa 58 like from 2 to 84 92 12 35 38 40 the current study could not find any isolates positive for blaoxa 58 like

albeit the reported co existence of oxas genes 29 41 42 coexistence between these genes was not observed in the current study and all a baumannii isolates only had one of the blaoxa 23 like or blaoxa 24 like genes

in the current study 42 3 and 79 4 of the isolates were mbl positive by dds test and mbl e test respectively

despite phenotypic tests no blaimp blavim and blaspm genes were detected by pcr and the isolates were negative for these genes

there are some possibilities about this phenomenon 1 the mbl production may be false positive and due to bactericidal activity of edta which may result in increased inhibitory zone and not associated with true mbl production 43 2 mbl production my be true positive due to other mbl genes such as blandm that were not investigated in the current study 44

similar results are reported that a baumannii isolates were mbl producer by phenotypic tests but no mbl encoding genes were detected 45 46

it is reported that mbl e test has good sensitivity for mbl detection and could detected mbl both chromosomally and plasmid mediated in aerobic and anaerobic bacteria 47

according to the e test results it is possible that the current study isolates were true mbl producers

interestingly the study found eight carbapenem resistant isolates that were negative for blaoxa 23 like blaoxa 24 like blaoxa 58 like and mbl genes and only harbored blaoxa 51 like

similarly nowak et al

reported that seven isolates of carbapenem resistant a baumannii only had blaoxa 51 like 29

carbapenem resistance in these isolates may be associated with other mechanisms such as modification of penicillin binding proteins loss of porins and decreased permeability ampc stable derepression or over expression of efflux pump 4 8 9

it is noteworthy that insertion of isaba1 in upstream of blaoxa 51 like can lead to caebapenem resistance in a baumannii 48

the relationship between harboring blaoxa 51 like and resistance to carbapenem in the eight isolates still need to be investigated

the current study also aimed to investigate the clonality of a baumannii isolates by rep pcr

genotypic comparison by rep pcr revealed that carbapenem resistant isolates belonged to six clones

all clones were spread in the icus

clone a was dominant 30 9 and clone f had the lowest prevalence 1

clonal dissemination of carbapenem resistant a baumannii was previously reported in different studies

it has been establish that multidrug resistant of a baumannii isolates with similar genotype can disseminate among various wards different hospitals and even among cities 4 10 12 49 51

in the current study the vast majority of carbapenem resistant isolates 94 97 96 9 belonged to one of the four dominant genotypes indicating clonal dissemination of resistant isolates in the studied hospitals

in conclusion overall the rate of carbapenem resistant isolates were high in the studied hospitals

colistin and polymyxin b were the effective antimicrobial agents in vitro

since in the current study blaoxa 58 like or mbl genes were not detected it seems that carbapenem resistance is mostly related to blaoxa 23 like and blaoxa 24 like and these genes may play an important role in carbapenem resistance in the isolates

in addition four clones of carbapenem resistant of a baumannii isolates are disseminated in the two studied hospitals and clone a was dominant

in accordance to other studies in the current investigation most of the resistant isolates belonged to four clones indicating clonal dissemination of a baumannii in the studied hospitals and that effective infection control strategies are necessary to control the spread of these resistant isolates

background a diversity of virulence factors work together to create the pathogenicity of staphylococcus aureus

these factors include cell surface components that promote adherence to surfaces as well as exoproteins such as panton valentine leukocidin pvl encoded by the luk pv genes that invade or bypass the immune system and are toxic to the host thereby enhancing the severity of infections caused by methicillin resistant staphylococcus aureus mrsa

objectives the aim of this study was to determine the frequency of pvl positive mrsa strains by real time pcr and their antibiotic susceptibility patterns by phenotypic test

materials and methods in total 284 staphylococcus isolates identified by phenotypic methods from clinical samples of shahrekord university hospitals shahrekord iran were tested for nuc mec a and pvl genes by taqman real time pcr

the antibiotic susceptibility patterns of pvl containing mrsa strains were determined via the disk diffusion method

results in total 196 isolates 69 were nuc positive i e s aureus of those isolates 96 49 were mec a positive mrsa

eighteen 18 8 of the 96 mrsa positive and 3 3 of the 100 methicillin susceptible staphylococcus aureus mssa strains were pvl positive

pvl positive mrsa strains were mostly recovered from tracheal specimens

eight pvl positive mrsa strains were resistant to all the tested antibiotics except vancomycin