European Journal of Cardiovascular Medicine

Pseudomonas aeruginosa is a gram-negative rod, aerobic, motile, and is leading cause of opportunistic nosocomial infections. It causes pneumonia, urinary tract infections, skin and soft tissue infections, burns infections, infections among immunocompromised individuals and 10% of all hospital acquired infections⁴. History of P. aeruginosa infection or colonization within the previous year, length of hospital stays, admitted in IPD or in the intensive care unit (ICU), mechanical ventilation, malignant disease and history of COPD are Predisposing factors for multidrug-resistant P.aeruginosa infection. Infections caused by P. aeruginosa are often severe, life-threatening and are difficult to treat due to low susceptibility to antimicrobial agents and high frequency of emergence of antibiotic resistance during therapy. Presence of extended spectrum β-lactamases, carbapenemases, aminoglycoside modifying enzymes and 16S ribosomal ribonucleic acid methylases causes antimicrobial resistance.

Mutational changes causing the up regulation of multidrug efflux pumps, derepression of amp C, modification of antimicrobial targets and changes in the outer membrane permeability barrier are ads to its resistance mechanisms.

Multi drug resistance is defined as non-susceptibility to at least one agent in three or more antipseudomonal categories i.e., aminoglycosides, carbapenems, cephalosporins, fluoroquinolones and penicillin or β-lactamase antibiotics^{1, 2}. P. aeruginosa isolates which remain susceptible to only one or two antipseudomonal drugs categorize in extremely drug resistance, similarly pan drug resistance isolate is non susceptible to all agents in all antipseudomonal agents i.e., no agents tested as susceptible for that isolate.  Thus, P. aeruginosa isolate that was characterized as extremely drug resistance also included multi drug resistance as.

Thus, emergence of multi drug resistance P. aeruginosa is of clinical concern and the pan drug-resistance isolates, treatable only with colistin, are on the rise.

 
Therefore, there is a need to conduct studies of P. aeruginosa for its prevalence, drug resistance and antimicrobial susceptibility patterns    to provide correct empirical treatment for patients.

Present study was conducted in the Department of Microbiology, Patna Medical College, Patna, Bihar, with the help of department of medicine, surgery, orthopedics, obstetrics and gynecology, eye, ENT and pediatrics during the period of October2020to October 2022.

A total of 7293 patients presenting with different complains in different OPD and IPD were included in the study. From all the 7293patients’ clinical samples such as pus, swab, urine, sputum, blood, cerebrospinal fluid, pleural fluid, peritoneal fluid, tissue biopsies and bronchial lavage were collected and received to the laboratory without delay for further processing.  All the data regarding patient's age, sex, admission into the hospital, duration of stay and special invasive procedure conducted was carried out on the basis of the case record history were noted. All the samples were processed according to standard CLSI guidelines⁹, ¹⁰. Samples were cultured on nutrient agar, blood agar and macconkeys agar, chocolate agar plates at 37°C for 24 hours. Suspected colonies of P. aeruginosa were identified and confirmed by using colonial morphology, motility test, Grams staining and biochemical tests and the production of the blue green pigment pyocyanin.

All the isolates of P. aeruginosa were tested for antibiotic susceptibility test by the standard Kirby-Bauer disc diffusion method according to CLSI guidelines^{9, 10}. The test inoculum was picked up with a calibrated sterile loop, suspended in peptone water and incubated at 37°C for 2 hours. The turbidity of the suspension was adjusted to 0.5 McFarland's standard. It was then inoculated on the Mueller Hinton Agar plate using sterile cotton swab.

The antibiotic disks used are Ciprofloxacin (5 mcg/disk), Gentamicin (10 mcg/disk), Amikacin (30 mcg/disk), Ceftazidime (30 mcg/disk), Piperacillin & tazobactam (100/10 mcg/disk), Imipenem (10 mcg/disk), Meropenem (10 mcg/disk), Levofloxacin (5 mcg/disk), Cefepime (30 mcg/disk) and Piperacillin (100 mcg/disk).

The plate was incubated at 37°C overnight. The zone of inhibition was measured by standard caliper and results are interpreted according to CLSI guidelines.  All media and antibiotic disks were supplied from HI media, Mumbai, India.

A total of 7293 clinical samples were aerobically cultured, out of which 3865 (52.9%) yielded significant growth and the rest 3428 (47.1%) samples were either sterile or showed non-significant growth(Table-4). From 3865 growth positive samples, a total of 355 (9.18%) P. aeruginosa were isolated (Table-5). From 355 isolates, majority 249 isolates (70.14%) were isolated from IPD in the hospital and rest 106 isolates (29.85%) were isolated from out-patients (community-acquired infection). 206 (5.32%) of P. aeruginosa were isolated from pus and swab samples followed by urine 126 (3.26%) and blood 01 (0.02%) samples (Table-3). The maximum age of patients infected with P. aeruginosa was 30-40 years old and male to female ratio was 1.25:1.(Table-2)

Pseudomonas aeruginosa was highly resistant to Ceftazidime 81.97%, Cefepime 64.50%, Piperacillin 41.42%, Ciprofloxacin 44.50%, Levofloxacin 36.05%, and Amikacin 30.42%. P. aeruginosa was least resistant to Imipenem 5.35%, followed by Meropenem 4.78% and Piperacillin &Tazobactam 9.57%, which can be considered as effective drugs in this present review (Table-7).

Out of 355 isolates, 79 (22.25%) isolates were sensitive to all antibiotics tested and 295 (83.05%) isolates were MDR. From 295 MDR P. aeruginosa isolates, 5 (1.69%) isolates were XDR. No isolate was found to be PDR(Table-6). 

P. aeruginosais the most common Gram-negative bacteria isolated from clinical samples and a big challenge for the doctors for the treatment of both communities acquired and hospital acquired infections for that culture and sensitivity of sample is mandatory to optimizing the clinical outcome.  The objective of the present study was to evaluate the epidemiological data of P. aeruginosaisolates and their antimicrobial resistance patterns against routinely used antipseudomonal antibiotics⁵. In our study, from 7293 clinical sample, 3865 significant growth occurred, from which 355 Pseudomonas aeruginosa isolates were obtained, with a prevalence rate of 9.18%. Similar prevalence rate of 9.3% was reported by Srinivas et al. in Andhra Pradesh, India¹⁵.  In comparison, higher prevalence rate of 32.1% and 20.3% was reported by Rajat et al. and Javiya et al. in Gujarat, India respectively¹⁴. 

Low prevalence of 2.1% was obtained by Okon et al. in south westnigeria¹². In this present study, majority 206 (5.32%) of P. aeruginosa isolates were isolated from pus and swab followed by urine 126 (3.26%) and sputum19 (0.49%). Similar findings were obtained by several authors.  Our study revealed P. aeruginosa infection was significantly associated among hospitalized, elderly and had received any type of invasive procedure such as catheterization, intubation or ventilation. P. aeruginosa is rarely included in normal flora. However, colonization rates may high due to long standing stay in hospital, especially with impaired immunity patients and persons under went mechanical ventilation, tracheostomy, catheterization, surgery or severe burns. 

Our study shows the frequency of MDR among P. aeruginosa. Out of 355 isolates, 79 (22.25%) isolates were sensitive to all antibiotics tested and 295 (83.05%) isolates were MDR. From 295 MDR P. aeruginosa isolates, 5 (1.69%) isolates were XDR. No isolate was found to be PDR. Similar MDR rate of 71% was reported by Mohan Sundaram et al. in Tamil Nadu, India¹⁴.  Gill et al. in Rawalpindi, Pakistan had studied 180 P. aeruginosa isolates, which were obtained from different clinical specimens. Out of these, 22.7% were MDR, while 11% and 4.3% were XDR and PDR, respectively¹⁵. 

The high percentage of MDR strains were isolated from different clinical specimens is problematic in the future. Accurate laboratory diagnosis, infection control and appropriate antibiotics are cornerstones in containment of drug resistant.
Study showed majority (81.97%) of isolates were resistant to Ceftazidime, followed by Cefepime 64.50%, Piperacillin 41.42%, Ciprofloxacin 44.50%, Levofloxacin 36.05%, Gentamicin 35.49% and Amikacin 30.42%^3,4,5. Same antibiotics resistant trends seen against P. aeruginosa were seen in different studies done in India.  

Imipenem, Meropenem and piperacillin & tazobactam were most sensitive antibiotics in our study, showed resistant rates of 5.35%, 4.78% and 9.57% respectively. Low resistance rate of P. aeruginosa to carbapenems and piperacillin & tazobactam may be due to higher cost least use of these drugs is also responsible.

The irrational, irrelevant and inappropriate use of antibiotics leads to development of antimicrobials resistance against P. aeruginosa.  Therefore, there is a need to strictly band themisuse of antimicrobials without laboratory detection and antimicrobial susceptibility testing. Surveillance of P. aeruginosa is essential for local monitoring of resistance pattern.