







































                     American International Journal of Multidisciplinary Scientific Research 

Vol. 6, No. 3; 2020 

                                       ISSN 2638-1249   E-ISSN 2638-1273 

Published by CRIBFB, USA 

 

1 

COMPARISON OF IN VITRO ACTIVITY OF COLISTIN WITH 

CEFTOLOZANE/TAZOBACTAM AGAINST MULTI DRUG RESISTANT 

PSEUDOMONAS AERUGINOSA “A LAST LINE TREATMENT AGAINST MDR” 

 

 

K. M. Anwarul Islam 

Associate Professor 

The Millennium University, Bangladesh 

 

Muhammad Aitmaud Uddolah Khan 

Assistant Professor  

Baqai Medical University, Pakistan  

 

 Sarah Azhar 

Senior Lecturer  

Baqai Medical University, Pakistan  

 

Muhammad Rashid Ahmed 

Professor 

Baqai Medical University, Pakistan  

 

Sumreen Khurram  

Lecturer 

Baqai Medical University, Pakistan  

 

Hina Masood  

Lecturer 

Baqai Medical University, Pakistan  

 

Lubna Farooq  

Assistant Professor  

Baqai Medical University, Pakistan  

 

 

ABSTRACT 

Objectives 

To evaluate and compare in vitro activity of Ceftolazane / Tazobactum and Colistin against Multi 

Drug Resistant (MDR) strains of Pseudomonas aeruginosa. 

 

Methodology 

After ethical approval this in vitro cross-sectional study was conducted from October 2017 to 

April 2018. Routine samples of pus, wound swabs, blood, tracheal aspirates and urine were 

collected and received from the in-patient and out-patient clinics. All the samples were submitted 

for culture and sensitivity testing at the microbiology laboratory of Ziauddin University Hospital, 



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North Nazimabad campus. All the samples were processed according to the provided 

microbiological procedures, CLSI Guidelines 2018. 

 

Results 

Forty sample from the out-patient clinics represented pre-dominance of Multi Drug Resistant 

strains of Pseudomonas aeruginosa (which was found to be 41.2%). On culture and sensitivity 

testing, it was observed that 60% of the MDR strains of P. aeruginosa were susceptible to 

Ceftolazane / Tazobactum which was markedly comparable to the susceptibility shown by 

Colistin (99%).Statistically, P value was highly significant and was found to be 0.0001. 

 

Conclusion 

Colistin showed superior activity as compared to Ceftolazane / Tazobactum against MDR 

isolates of P. aeruginosa. Thus, Colistin has proven to be a possible and important alternative 

against MDR isolates of P. aeruginosa, but due to its narrow therapeutic window and toxicity 

profile this drug can be used only when there is no working alternative, or the infection is 

severely debilitating. 

 

Keywords: Gram-Negative Infection, P. Aeruginosa, Resistant. 

 

INTRODUCTION 

Antibacterial drug are the main therapeutic agents in medicine to treat broad spectrum diseases 

caused by bacterial infections. In modern science, antibiotic development is one of the 

milestones. Millions of lives all over the world are saved daily because of the use of antibiotic 

agents. But there is an important threat round the globe – the emergence of resistance against 

antibacterial agents (Ventola, 2015).  

Irrational and over the counter use of antibiotics result in emergence of resistant isolates 

of bacteria which do not respond to drug therapy (Buke et al., 2005).  

Antibacterial drug resistance threatens this milestone and has become a significant risk to 

health of mankind. Antibacterial resistance is now a major clinical concern round the globe and 

is a major public health problem of the current century (Levy, 2002).  

P. aeruginosa is a very ubiquitous microorganism, present in many natural and artificial 

environments (Haley, Colmer-Hamood, & Hamood, 2012). 

P. aeruginosa has a unique grape like odour of aminoacetophenone on culture media / 

agar (Cox, & Parker, 1979). It colonizes naturally on skin, in nasal mucosa, throat and also in 

fecal samples. P. aeruginosa is a nosocomial pathogen. It is also an opportunistic organism and 

causes life threatening infections in immune-compromised individuals (Kielhofner, Atmar, 

Hamill, & Musher, 1992). 

According to the data provided by the Center for the Diseases Control and Prevention 

(CDC), P. aeruginosa can cause a wide variety of infections and is also one of the most common 

infectious agents for nosocomial pneumonia (Cross et al., 1983), urinary tract infections, 

ophthalmitis, otitis, surgical wound infections and bacteremia (Trautmann, Halder, Hoegel, 

Royer, & Haller, 2008).) Another study revealed that P. aeruginosa is also a leading cause of 

morbidity and mortality in patients of cystic fibrosis (Kerem, Corey, Gold, & Levison, 1990). 

Colistin is a Polymyxin B antibiotic, which was used as a therapeutic agent for gram 

negative organisms. (Evans, Feola, & Rapp, 1999) Due to severe nephrotoxicity and 



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neurotoxicity after the therapeutic use of Colistin, its use was diminished (Wolinsky & Hines, 

1962). 

Currently due to severe resistance shown by bacteria, Colistin (Polymiyxin B) has re-

emerged as a last line treatment modality for Multi Drug Resistant isolates of P. aeruginosa, 

acinetobacter baumannii and Klebseilla pneumonia. 

According to our knowledge, in Pakistan no current data is available for usage of 5th 

generation Cephalosporin comparison with Colistin. Antibiotic resistance, an emerging problem 

and a clinical concern to treat uropathogenic P.aeruginosa, it is now a high time to look for more 

specific and sensitive antibacterial agents to treat resistant infections. 

The aim of this study is to ascertain the prevalence of P. aeruginosa, in the population of 

Karachi. Another aim is to determine and compare the sensitivity of Ceftolozane / Tazobactum, a 

novel 5th generation Cephalosporin. With the sensitivity of Colistin – as it is the last line defense 

option against Multi Drug Resistant (MDR) strains of P. aeruginosa. 

 

MATERIALS AND METHODS 

This was a Quasi experimental investigation and samples were gathered utilizing nonprobability 

strategy. Study was directed from October 2017 to April 2018 at Ziauddin University Hospital, 

Karachi.  

Samples were gathered from the inpatient wards and outpatient clinics, subsequently 

submitted to Microbiology Lab of Ziauddin University Hospital, North Nazimabad campus, 

Karachi, for culture and sensitivity. Routine samples were taken including pus discharge, wound 

swabs, blood, tracheal aspirates and urine.  

Samples were treated as per microbiological procedures CLSI Guidelines 2018. After an 

informed and written consent detailed data of the patients and organisms was recorded on a 

different survey form.  

All non-lactose fermenting growths on MacConkey's Agar were collected and stained 

with Gram stain and biochemical tests (motility, pigment presentation, citrate, catalase and 

oxidase tests) were run.  

Data was scrutinized by utilizing Statistical Package for Social Sciences (SPSS) vesion 

21. Descriptive investigations for numerical variables have been referenced as Mean with 

Standard Deviation.  

Frequencies and percentages were determined for susceptibility of antibacterial drugs and 

MDR strains of P. aeruginosa from different clinical samples. Zones of Inhibition were 

deciphered according to CLSI Guidelines 2018. Chi Square test was applied to gauge the 

relationship among sensitivity and resistance patterns of antimicrobial medications. A P-value< 

0.05 was considered as factually critical. 

 

RESULTS 

A sum of 176 strains of Pseudomonas was segregated out of which 97 were MDR P. aeruginosa. 

The pre-dominant bulk of MDR P. aeruginosa segregates were acquired from outpatient division, 

40 isolates (41.2%) and least were gathered from gynecology ward, 3 isolates (4.1%) as appeared 

in table 2.  

It was discovered that 60.0% of the MDR P. aeruginosa strains were found susceptible to 

Ceftolozane / Tazobactum but when contrasted with Colistin the sensitivity came out to be 99%. 

P value was discovered to be statistically significant (p value = 0.0001) as appeared in table 3. 



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Table 1. Gender wise frequency of MDR P. aeruginosa 

Gender   MDR   

97(55 %)  

Non MDR 

79 (45%)  

P value  

Male   45 (46 %)  40 (50.6 %)        0.59  

Female   52 (54 %)  37 (46.8 %)  

Table 2. Percentage of MDR isolates in different departments  

Department   MDR Non MDR  P value   

Gynecology ward  3 (4.1)  0 (0.0)   

 

0.29  
Intensive care unit 16 ( 16.5)  17 (21.5)  

Surgical ward   26(27.1)  30 (38.0)  

Outpatient department 40(41.2)  24(30.4)  

 Medicine ward   11(11.3)  8(10.1)  

Table 3. Comparison of susceptibility results of Colistin and C/T by disc diffusion method  

Antibiotics  Susceptible                

N (%)  

 Resistant   

N (%)  

 P value   

Colistin 

Ceftolozane/Tazobactam 

99(99%)  

58 (60.0%)  

1 (1%)  

39 (40%)  

 

0.0001  

  

DISCUSSION 

In immune-compromised patients, diseases such as Pneumonia, Bacteremia, Urinary Tract 

Infections, Infections of Skin and other soft tissues are usually linked with a notorious / harmful 

gram negative, aerobic rod-shaped bacillus called Pseudomonas aeruginosa (El Baze et al., 

1991).  

Clinical isolates of P.aeruginosa show resistance to a lot of classes of antibiotic drugs and 

have left clinicians with a few choices of course of therapy for infectious diseases (Kalantar, 

2012; Rossolini, & Mantengoli, 2005) 

Research studies conducted in different areas/countries of the world also support/exhibit 

increased prevalence rate of MDR P.aeruginosa. A research performed in India in 2017, at a 

tertiary care setup demonstrated 85% prevalence rate of P. aeruginosa (Yuliandra, 2017). 

Another study conducted in Egypt showed highest incidence of P.aeruginosa at the burns 

unit as well as in ICU (Mahmoud, Zahran, Hindawi, Labib, & Galal, 2013). Another high 

frequency was also noted in Egypt (56%) (Farooq, Memon, Ismail, & Sadiq, 2019). 

In Texas a research was conducted in 2010, that revealed a bulk of involvement of MDR 

P. aeruginosa from gynecology / obstetrics unit (4.1%), medicine ward (11.3%), ICU (16.5%) 

and from surgical ward (26.8%). Another study was conducted and found to support the role of 

P. aeruginosa in 10 ICU’s in France that helped in identifying individual and environmental ICU 

risk factors that aid in acquiring P. aeruginosa infections (Venier et al., 2014) 



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 In this study Multi-Drug Resistant strains of P. aeruginosa were found predominantly in 

the female population and the result was 64%, in comparison to the male population in which the 

result was 46%. The results are similar to a research conducted in Nepal, which revealed MDR 

P. aeruginosa strains were (64%) higher in females while (31%) lower in males (Kattel, 2012). 

Another study on UTI also supported higher incidence of infection by P. aeruginosa in 

female population as compared to male population. Women aged between 20-40 years show 

incidence ranging from 25 - 30% in contrast to older women aged 60 years or more who showed 

an incidence ranging from 4 - 43% (Mittal, Aggarwal, Sharma, Chhibber, & Harjai, 2009). 

In 2013, a cross sectional study was done in a teaching hospital of Ethiopia from January 

to May and urine samples were collected from 73 patients who were catheterized and developed 

urinary tract infections. Out of those 73 patients, P. aeruginosa was found in urine samples of 36 

patients (49.32%) who were catheterized, out of which 17 were males (23.29%) and 19 were 

females (26.03%). After antibiotic sensitivity testing, all clinical isolates of P. aeruginosa were 

susceptible to Norfloxacin and Ciprofloxacin. Susceptibility to Gentamicin was also noted and 

was found to be 86.12% (Bekele, Tesfaye, Sewunet, & Waktola, 2015). 

Geographical variation and duration of study may also act as an influencing factor that is 

associated with the difference in gender prevalence. 

In our study, it was found that MDR strains of P. aeruginosa are 99%susceptible to 

Colistin (Polymyxin B). Another research conducted in Pakistan also supported our study and 

demonstrated that Colistin (Polymyxin B) is the most sensitive antibacterial option among the 

antibiotic regimen options (Gill, 2011). 

Polymyxin B antibacterial drug, also called Colistin is used as a therapeutic agent against 

gram negative bacilli. All over the world and in our country Polymyxin B, is a sensitive 

antibacterial therapeutic agent but due to its narrow therapeutic index and noteworthy side 

effects, the empirical use of this medicine is very finite (Landersdorfer, & Nation, 2015). 

Colistin was found to have a better in vitro function (98%) which is significantly 

comparable to Tazobactum / Ceftalozane (60%) when diffuse disc method of antibiotic 

sensitivity was applied. 

Increased resistance of bacterial to antibiotic drugs, side effects and toxicities, 

pharmacokinetics, therapeutic uses, clinical findings and combination therapy in relation to 

Colistin (Polymyxin B) has been reviewed (Pfaller, Shortridge, Sader, Flamm, & Castanheira, 

2017). 

Current methods to utilize Colistin with other antibacterial drugs can be fruitful for 

increased antibacterial / antibiotic efficacy. In 21st century, it can be predicted that against Multi-

Drug Resistant gram-negative bacillus - Colistin will be the last line of defense among all 

antibacterial therapeutic agents (Biswas, Brunel, Dubus, Reynaud-Gaubert, & Rolain, 2012). As 

Ceftolazane / Tazobactum is not a drug a choice in our set up, still 40% resistance was 

demonstrated in the results. This can be due to cross resistance that is if the patient is resistant to 

one group of Cephalosporin then cross resistance may develop to newer agents of 

Cephalosporins. 

 

CONCLUSION 

Resistance of Pseudomonas aeruginosa against antibiotic agents is amplified over a past few 

years. Previously Colistin was considered a last resort therapy for various Multi Drug Resistant 

bacteria in clinical set up. Fortunately, Ceftolozane / Tazobactum a comparatively newer 

antibiotic, the therapeutic use of Ceftolozane / Tazobactum should be reserved only for severe 



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and life-threatening infections. This is particularly true where the infection is polymicrobial, 

anaerobic or Pseudomonas resistant to other antimicrobial drugs. 

 

 

REFERENCES 

Biswas, S., Brunel, J. M., Dubus, J. C., Reynaud-Gaubert, M., & Rolain, J. M. (2012). Colistin: 

an update on the antibiotic of the 21st century. Expert review of anti-infective therapy, 

10(8), 917-934. 

Bekele, T., Tesfaye, A., Sewunet, T., & Waktola, H. D. (2015). Pseudomonas aeruginosa 

isolates and their antimicrobial susceptibility pattern among catheterized patients at 

Jimma University Teaching Hospital, Jimma, Ethiopia. BMC research notes, 8(1), 488. 

Buke, C., Hosgor-Limoncu, M., Ermertcan, S., Ciceklioglu, M., Tuncel, M., Köse, T., Eren, S. 

(2005). Irrational use of antibiotics among university students. Journal of infection. 

51(2), 135-9. 

Cox, C. D., & Parker, J. (1979). Use of 2-aminoacetophenone production in identification of 

Pseudomonas aeruginosa. Journal of clinical microbiology, 9(4), 479-484. 

Cross, A., Allen, J. R., Burke, J., Ducel, G., Harris, A., John, J., ... & Skalova, R. (1983). 

Nosocomial infections due to Pseudomonas aeruginosa: review of recent trends. Reviews 

of infectious diseases, 5(Supplement_5), S837-S845. 

Evans, M. E., Feola, D. J., & Rapp, R. P. (1999). Polymyxin B sulfate and colistin: old 

antibiotics for emerging multiresistant gram-negative bacteria. Annals of 

Pharmacotherapy, 33(9), 960-967. 

El Baze, P., Thyss, A., Vinti, H., Deville, A., Dellamonica, P., & Ortonne, J. P. (1991). A study 

of nineteen immunocompromised patients with extensive skin lesions caused by 

Pseudomonas aeruginosa with and without bacteremia. Acta dermato-venereologica, 

71(5), 411. 

Farooq, L., Memon, Z., Ismail, M. O., & Sadiq, S. (2019). Frequency and antibiogram of multi-

drug resistant pseudomonas aeruginosa in a Tertiary Care Hospital of Pakistan. Pakistan 

journal of medical sciences, 35(6), 1622. 

Gill, M. M., Usman, J., Kaleem, F., Hassan, A., Khalid, A., Anjum, R., & Fahim, Q. (2011). 

Frequency and antibiogram of multi-drug resistant Pseudomonas aeruginosa. J Coll 

Physicians Surg Pak, 21(9), 531-534. 

Haley, C. L., Colmer-Hamood, J. A., & Hamood, A. N. (2012). Characterization of biofilm-like 

structures formed by Pseudomonas aeruginosa in a synthetic mucus medium. BMC 

microbiology, 12(1), 181. 

Kielhofner, M., Atmar, R. L., Hamill, R. J., & Musher, D. M. (1992). Life-threatening 

Pseudomonas aeruginosa infections in patients with human immunodeficiency virus 

infection. Clinical infectious diseases, 14(2), 403-411. 

Kerem, E., Corey, M., Gold, R. T., & Levison, H. (1990). Pulmonary function and clinical 

course in patients with cystic fibrosis after pulmonary colonization with Pseudomonas 

aeruginosa. The Journal of pediatrics, 116(5), 714-719. 

Kalantar, E., Torabi, V., Salimizand, H., Soheili, F., Beiranvand, S., & Dallal, M. M. S. (2012). 

First Survey of metallo-β–lactamase producers in clinical isolates of Pseudomonas 

aeruginosa from a referral burn center in Kurdistan province. Jundishapur journal of 

natural pharmaceutical products, 7(1), 23. 



 https://www.cribfb.com/journal/index.php/aijmsr    American International Journal of Multidisciplinary Scientific Research    Vol. 6, No. 3; 2020 

7 

Kattel, H. P., Mishra, S. K., Acharya, J., Sigdel, M. R., Prasad, N., Shah, A. S. S., ... & Pokhrel, 

B. M. (2012). Antibiotic sensitivity profile of different uropathogens in a tertiary care 

center in Nepal. Journal of Nepal Association of Medical Laboratory Science, 11(1), 19-

33. 

Levy, S. B. (2002). Factors impacting on the problem of antibiotic resistance. Journal of 

Antimicrobial Chemotherapy, 49(1), 25-30. 

Landersdorfer, C. B., & Nation, R. L. (2015, February). Colistin: how should it be dosed for the 

critically ill?. In Seminars in respiratory and critical care medicine (Vol. 36, No. 01, pp. 

126-135). Thieme Medical Publishers. 

Mahmoud, A. B., Zahran, W. A., Hindawi, G. R., Labib, A. Z., & Galal, R. (2013). Prevalence 

of multidrug-resistant Pseudomonas aeruginosa in patients with nosocomial infections at 

a university hospital in Egypt, with special reference to typing methods. J Virol 

Microbiol, 13, 165-59. 

Mittal, R., Aggarwal, S., Sharma, S., Chhibber, S., & Harjai, K. (2009). Urinary tract infections 

caused by Pseudomonas aeruginosa: a minireview. Journal of infection and public 

health, 2(3), 101-111. 

Pfaller, M. A., Shortridge, D., Sader, H. S., Flamm, R. K., & Castanheira, M. (2017). 

Ceftolozane–tazobactam activity against drug-resistant Enterobacteriaceae and 

Pseudomonas aeruginosa causing healthcare-associated infections in Australia and New 

Zealand: Report from an Antimicrobial Surveillance Program (2013–2015). Journal of 

global antimicrobial resistance, 10, 186-194. 

Rossolini, G. M., & Mantengoli, E. (2005). Treatment and control of severe infections caused 

by multiresistant Pseudomonas aeruginosa. Clinical Microbiology and infection, 11, 17-

32. 

Trautmann, M., Halder, S., Hoegel, J., Royer, H., & Haller, M. (2008). Point-of-use water 

filtration reduces endemic Pseudomonas aeruginosa infections on a surgical intensive 

care unit. American journal of infection control, 36(6), 421-429. 

Venier, A. G., Leroyer, C., Slekovec, C., Talon, D., Bertrand, X., Parer, S., ... & Clair, B. 

(2014). Risk factors for Pseudomonas aeruginosa acquisition in intensive care units: a 

prospective multicentre study. Journal of Hospital Infection, 88(2), 103-108. 

Ventola, C. L. (2015). The antibiotic resistance crisis: part 1: causes and threats. Pharmacy and 

therapeutics, 40(4), 277. 

Wolinsky, E., & Hines, J. D. (1962). Neurotoxic and nephrotoxic effects of colistin in patients 

with renal disease. New England Journal of Medicine, 266(15), 759-762. 

Yuliandra, Y. (2017). Antibacterial Resistance Pattern of Pseudomonas Aeruginosa Isolated 

from Clinical Samples at A General Hospital in... 

 

 

 

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