pseudomonas aeruginosa is a common gram - negative rod - shaped bacterium that leads to significant morbidity and mortality in humans .
p. aeruginosa is a prototype of  multidrug - resistant pathogen  and is recognized for its ubiquitous distribution , advanced antibiotic resistance mechanisms , and nosocomial infections .
p. aeruginosa has the ability to survive on minimal nutrition and tolerate a variety of physical insults leading to its persistence in the community and hospital settings . despite the wide distribution of p. aeruginosa in nature and the potential for community - acquired infections , serious infections with this bacterium
p. aeruginosa was identified as the fifth most frequently isolated nosocomial pathogen by the surveillance data from the united states .
p. aeruginosa is one of the major causes of hospital - acquired infections and is responsible for about 1020% of nosocomial infections in patients admitted in the intensive care units ( icus ) .
p. aeruginosa can be isolated from a wide variety of sources in the hospital , including respiratory equipment , antiseptics , soaps , sinks , mops , medicines , and physiotherapy tools .
p. aeruginosa is divided into different phenotypes based on the drug resistance patterns of the organism .
multidrug - resistant ( mdr ) phenotype is defined as p. aeruginosa , which is resistant to more than one antimicrobial agent in three or more antimicrobial categories .
a similar resistance to more than one antimicrobial agent in <3 antimicrobial categories is defined as drug - resistant ( dr ) p. aeruginosa .
the details of the antimicrobial agents and categories used to define the phenotypes are given in table 1 .
extensively dr ( xdr ) phenotype is defined as p. aeruginosa , which is resistant to more than one antimicrobial agent in all the antimicrobial categories , except in two or less .
pan - dr ( pdr ) phenotype is defined as a bacterium which is resistant to all antimicrobial agents in all antimicrobial categories .
antimicrobial categories and agents used to define the pseudomonas aeruginosa phenotypes along with percentage of resistant strains mdr , xdr , and pdr phenotypes elaborate inactivating enzymes , such as extended - spectrum beta - lactamases ( esbl ) and metallo--lactamases ( mbl ) , that make beta - lactams and carbapenems ineffective .
esbl - producing p. aeruginosa was initially detected in europe in the mid-1980s , and mbl - producing p. aeruginosa was first reported from japan in 1991 .
literature is sparse regarding the incidence of different phenotypes of p. aeruginosa from our country as we could retrieve only two articles in the pubmed with the relevant ( p. aeruginosa , india , phenotype , incidence ) keywords .
hence , we conducted this study to find the incidence of mdr , xdr , and pdr phenotypes of p. aeruginosa in the icu of a tertiary care hospital .
this prospective , observational study was conducted at the department of microbiology of a tertiary level hospital for over a period of 2 years from january 2014 to december 2015 .
we included all patients who were at least 10 years of age at the time of the admission to the icu of this hospital .
as per our hospital policy , patients below 10 years of age requiring intensive are admitted to the pediatric icu .
our study does not include data from the pediatric icu , thereby resulting in the exclusion of patients below 10 years of age .
the patient with evidence of septicemia and known diagnosis of p. aeruginosa infection at the time of admission was excluded from the study .
routine hematology and biochemistry tests were conducted as per the request of the clinical team .
microbiological specimens were collected from the blood , urine , and sputum samples of the patients .
other samples were collected based on the clinical suspicion from a site harboring infection , such as throat swab , wound discharge , and body fluid culture .
samples obtained after an invasive procedure and from the indwelling catheters were also included in the study .
a total of 100 environmental samples were collected as part of active surveillance of the hospital environment and staff , which were grouped as group 2 .
these samples were collected from the medical staff ( hand , throat , and nasal swabs ) and the hospital environment ( air , surgical instruments , dressing material , floors , door , walls , beds , sinks , and antiseptic solutions ) . all blood culture and fluid samples with a minimum volume of 3 ml
the bact / alert system is a continuously monitored blood culture system for detecting bacteremia and fungemia .
bottles flagged as positive by the bact / alert system were subcultured and interpreted according to the standard laboratory protocols .
samples other than the blood and body fluids of group 1 and all group 2 were cultured on macconkey agar and blood agar .
these plates were incubated overnight at 37c and all the bacteria grown in these culture media were processed for identification and antibiotic susceptibility testing using automated bacterial system vitek 2 system ( biomrieux ) .
vitek 2 system uses a new fluorescence - based technology used for the identification and susceptibility testing of bacteria and is compliant with the clinical and laboratory standard institute ( clsi ) guidelines 2014 .
p. aeruginosa was identified by its colony characteristics , pigment production , grape - like odor , oxidase positivity , motility , gram - negative character of the bacilli , ability to decarboxylate arginine and to grow at 42c .
antibiotic sensitivity patterns of these isolates were studied by minimal inhibitory concentration using the vitek 2 system as per the clsi 2014 guidelines .
strains which had the same types of resistance patterns ( antibiotype ) were considered to be from the same clone .
this prospective , observational study was conducted at the department of microbiology of a tertiary level hospital for over a period of 2 years from january 2014 to december 2015 .
we included all patients who were at least 10 years of age at the time of the admission to the icu of this hospital .
as per our hospital policy , patients below 10 years of age requiring intensive are admitted to the pediatric icu .
our study does not include data from the pediatric icu , thereby resulting in the exclusion of patients below 10 years of age .
the patient with evidence of septicemia and known diagnosis of p. aeruginosa infection at the time of admission was excluded from the study .
routine hematology and biochemistry tests were conducted as per the request of the clinical team .
microbiological specimens were collected from the blood , urine , and sputum samples of the patients .
other samples were collected based on the clinical suspicion from a site harboring infection , such as throat swab , wound discharge , and body fluid culture .
samples obtained after an invasive procedure and from the indwelling catheters were also included in the study .
a total of 100 environmental samples were collected as part of active surveillance of the hospital environment and staff , which were grouped as group 2 .
these samples were collected from the medical staff ( hand , throat , and nasal swabs ) and the hospital environment ( air , surgical instruments , dressing material , floors , door , walls , beds , sinks , and antiseptic solutions ) . all blood culture and fluid samples with a minimum volume of 3 ml
the bact / alert system is a continuously monitored blood culture system for detecting bacteremia and fungemia .
bottles flagged as positive by the bact / alert system were subcultured and interpreted according to the standard laboratory protocols .
samples other than the blood and body fluids of group 1 and all group 2 were cultured on macconkey agar and blood agar .
these plates were incubated overnight at 37c and all the bacteria grown in these culture media were processed for identification and antibiotic susceptibility testing using automated bacterial system vitek 2 system ( biomrieux ) .
vitek 2 system uses a new fluorescence - based technology used for the identification and susceptibility testing of bacteria and is compliant with the clinical and laboratory standard institute ( clsi ) guidelines 2014 .
p. aeruginosa was identified by its colony characteristics , pigment production , grape - like odor , oxidase positivity , motility , gram - negative character of the bacilli , ability to decarboxylate arginine and to grow at 42c .
antibiotic sensitivity patterns of these isolates were studied by minimal inhibitory concentration using the vitek 2 system as per the clsi 2014 guidelines .
strains which had the same types of resistance patterns ( antibiotype ) were considered to be from the same clone .
the mean age of the patients who were included in the study was 36.2 years .
a total of 597 pathogenic bacteria were isolated from the 1915 clinical specimens , giving a culture positivity rate of 31.2% for the clinical specimen .
the details of all the bacterial species isolated from the study samples are shown in figure 1 .
other bacteria such as coagulase - negative staphylococci , staphylococcus aureus , escherichia coli , and proteus spp . accounted for the rest of the bacterial cultures .
hospital staff and group 2 samples did not grow any pathogenic bacterium , including p. aeruginosa .
pattern of microbes isolated in the study sample the incidence rate of p. aeruginosa was highest ( 78% ) in the age group of patients between 20 and 50 years .
urine ( 47 out of 88 ) and wound ( 38 out of 88 ) samples accounted for the majority of the positive isolates .
the prevalence of p. aeruginosa phenotypes based on the resistance patterns is shown in figure 2 .
our data showed that 47.7% strains were dr , 50% were mdr , and 2.3% were of xdr phenotype .
no strains were resistant to all antibiotics in all antimicrobial categories as all the strains were found to be sensitive to fosfomycin and colistin ( 100% ) .
our study showed the prevalence of drug resistance in almost 98% of the isolates of p. aeruginosa in the icu . the only solace is the findings of the 0% presence of pdr phenotype , thereby showing the efficacy of certain antibiotics against this organism .
piperacillin resistance was found to be 70% in our study , which is comparable to a report showing it to be 73% .
emergence of resistance to beta - lactams in p. aeruginosa has become a serious threat , particularly against the third- and fourth - generation cephalosporins .
there are a lot of molecular mechanisms involved for resistance against these antibiotics , generation of esbl enzyme , incorporation of bla genes in integrons , and inability of porin genes to enhance their expression level and/or alteration of antibiotic target sites .
ceftazidime and cefepime are the prescribed antipseudomonal third- and fourth - generation cephalosporins , respectively .
the resistance to ceftazidime and cefepime observed in our study was similar to that of a previous report from india .
our study showed that 80% of p. aeruginosa were resistant to carbapenem antibiotics such as imipenem and meropenem .
previous studies showed a similar trend from other countries and a few authors had shown 100% resistance against carbapenems .
this suggests the declining efficacy of the carbapenems as an effective antibiotic in the management of nosocomial infections .
fluoroquinolone compounds are one of the important antimicrobial agents that have been used for a variety of infections .
new generation fluoroquinolones are beneficial against gram - negative and gram - positive bacteria , whereas older fluoroquinolones were effective against aerobic gram - negative bacteria only .
our data showed 96% resistance against ciprofloxacin and 67% resistance against levofloxacin while 100% resistance against ciprofloxacin was demonstrated earlier .
our data showed similar resistance pattern between amikacin and gentamicin , which was similar to that of the published literature .
similar data were not available for comparison with other authors about the sensitivity to aztreonam .
similar data were reported from other countries where there is a high prevalence of p. aeruginosa infection . to the best of our knowledge ,
this is the first study from india that defines the prevalence of mdr , xdr , and pdr p.
the strengths of our study include long duration of observation and the use of highly advanced automated bacteria identification system in the identification of p. aeruginosa . the limitations of our study include data derived from a single hospital may not be applicable to other geographic locations and inability to check resistance pattern to all the antipseudomonal drugs .
mdr p. aeruginosa is responsible for serious nosocomial infections among the patients admitted in the icus of the hospital .
epidemiological studies and strict laws regarding antibiotic policies should be constructed to limit the unnecessary use of antibiotics so that spread of multidrug resistance can be avoided .
 background : infection by pseudomonas aeruginosa is common in the intensive care unit ( icu ) , leading to increased morbidity and mortality . the organism is classified into various phenotypes based on the drug resistance pattern , namely , drug - resistant ( dr ) , multi - dr ( mdr ) , extensively dr ( xdr ) , and pan - dr ( pdr ) . 
 we aim to study the incidence of p. aeruginosa phenotypes in a tertiary level icu.materials and methods : we conducted this prospective , observational study for 2 years ( january 2014-december 2015 ) and collected appropriate clinical samples ( blood , urine , wound discharge , etc . 
 , ) from all the patients admitted to icu . 
 we excluded patients with known septicemia and p. aeruginosa infection . 
 group 1 comprised a total 1915 patient samples and group 2 comprised 100 active surveillance samples , collected from the medical staff and the hospital environment . 
 the data were analyzed using appropriate statistical methods , and a p < 0.05 was considered statistically significant.results:we isolated 597 pathogenic bacteria out of 1915 specimens , giving a culture positivity rate of 31.2% . 
 klebsiella ( 43% ) , acinetobacter ( 22% ) , and p. aeruginosa ( 15% ) were the top three isolated bacteria . 
 none of the surveillance samples grew p. aeruginosa . 
 antibiotic resistance studies revealed that 47.7% of p. 
 aeruginosa isolates were dr , 50% were mdr , and 2.3% were xdr phenotype . 
 none of the strains showed pdr phenotype.conclusion:our data revealed a high prevalence of dr phenotypes of p. aeruginosa in the icu . 
 judicious use of antibiotics and strict infection control measures are essential to reduce the prevalence of drug resistance . 
INTRODUCTION
MATERIALS AND METHODS
Hospital setting
Sample collection and processing
Microbial identification and antibiotic susceptibility testing
RESULTS
DISCUSSION
CONCLUSION
Financial support and sponsorship
Conflicts of interest