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Year : 2014  |  Volume : 51  |  Issue : 4  |  Page : 477--480

Characterization and anti-microbial susceptibility of bacterial isolates: Experience from a tertiary care cancer center in Delhi

R Singh1, S Jain2, R Chabbra2, R Naithani1, A Upadhyay1, M Walia1,  
1 Department of Oncology, Max Super Speciality Hospital, Patparganj, New Delhi, India
2 Department of Lab Medicine, Max Super Speciality Hospital, Patparganj, New Delhi, India

Correspondence Address:
R Singh
Department of Oncology, Max Super Speciality Hospital, Patparganj, New Delhi


Background: Hospitalization for fever in cancer patients is associated with considerable morbidity, mortality, and cost. AIM: The aim of this study was to study the bacterial spectrum and susceptibility patterns of pathogens in culture positive patients from the oncology unit of our hospital. Methods: We retrospectively reviewed the medical records of patients admitted in our cancer center (medical, radiation, and surgical oncology) from January to December 2013. Blood and respiratory secretions from the indoor patients were evaluated. Results: Of the total 693 samples, 76.4% were Gram-negative and 23.6% were Gram-positive. The most common bacterial isolates among Gram-negative organisms in blood were Escherichia coli, Salmonella and among the Gram-positive organism were Staphylococcus aureus and Enterococcus. Among the blood isolates extended spectrum of beta-lactamase, multidrug-resistant (carbapenem-resistant) and pan resistant bugs were seen in 47%, 15%, and 5% of the blood isolates. Among the Gram-positive organisms, 25% respiratory isolates were vancomycin-resistant Enterococci. Conclusion: We observed a high incidence of Gram-negative isolates with clinically significant resistance to first-line antibiotics such as cephalosporin's, piperacillin tazobactum, and fluoroquinolones.

How to cite this article:
Singh R, Jain S, Chabbra R, Naithani R, Upadhyay A, Walia M. Characterization and anti-microbial susceptibility of bacterial isolates: Experience from a tertiary care cancer center in Delhi.Indian J Cancer 2014;51:477-480

How to cite this URL:
Singh R, Jain S, Chabbra R, Naithani R, Upadhyay A, Walia M. Characterization and anti-microbial susceptibility of bacterial isolates: Experience from a tertiary care cancer center in Delhi. Indian J Cancer [serial online] 2014 [cited 2020 Jan 18 ];51:477-480
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Infections are the major cause of morbidity and mortality in these immune-compromised subset of patients. Hospitalization with febrile or nonfebrile neutropenia lead to major economic and social burden for the patient and the hospitals. Algorithmic approaches to fever and neutropenia, infection prophylaxis, diagnosis, and treatment have been established by various international organization such as Infectious Diseases Society of America [1] and European Conference on Infections in Leukemia.[2] These guidelines though provide empirical choices for antibiotics and antifungal, but local microbiology and an antibiotic sensitivity pattern still govern the first line antibiotics in these critical ill patients. The objective of this study was to determine the types of pathogens causing infections and their antimicrobial susceptibility profile in oncology patients.


In this study, positive cultures (blood and respiratory isolates) obtained from patients hospitalized (IPD and high dependency unit [HDU]/Intensive Care unit [ICU]) under surgical, radiation and medical oncology at Max Cancer Centre, Patparganj, New Delhi from January 2013 to December 2013 were retrospectively evaluated. Paired blood cultures were taken in aerobic media, that is, Fastidious Antimicrobial Neutralization Plus media (FAN ® Plus) which offers optimized time to detect and incubated in Bact Alert three-dimensional (3D) system by BioMerieux, France. BacT/ALERT 3D's patented colorimetric sensor-and-detection technology which detects microorganisms by tracking CO2 production. The notification of positives is immediate and results are dependable. Identification and antimicrobial susceptibility testing of the isolates to antimicrobial agents were performed using the Vitek 2 compact system (BioMerieux, France) according to the recommendations of the Clinical and Laboratory Standards Institute. Extended spectrum of beta-lactamase (ESBL) confirmation was performed by the Vitek 2 compact system only. An analysis of the microbiological spectrum and the antibiotic sensitivity pattern of the bacterial isolates were performed by VITEK ® 2 test cards for identification GN ID card for Gram-negative bacterial identification and GP ID card for Gram-positive bacterial identification, YST ID Card for Yeast identification. Antibiotic susceptibility testing Gram-positive antibiotic susceptibility testing (AST) cards, Gram-negative antibiotic susceptibility testing (AST) cards, and Yeast antibiotic susceptibility testing (AST) card.

An analysis of the microbiological spectrum and the antibiotic sensitivity pattern of the bacterial isolates were performed. In this study, the procedures followed were in accordance with the ethical standards and also with the Helsinki Declaration as revised in 2000.


The total bacterial isolates from blood and respiratory secretions sent to the microbiology laboratory from the indoor, ICU, and HDU patients were analyzed. Of the total 693 samples (n = 530) 76.4% were Gram-negative and (n = 163) 23.6% were Gram-positive [Table 1]. The contribution of the most prevalent bacterial isolates is given in [Table 2]. The most common bacterial isolates among Gram-negative organisms in blood were Escherichia coli (23.5%), Salmonella (17.74%), and Klebsiella spp. (13.4%). Among the Gram-positive organism, the most common were Staphylococcus aureus (34.3%) and Enterococcus (29.0%).{Table 1}{Table 2}

The antibiotic sensitivity pattern of the organism isolated from the blood has been detailed in [Table 3a] and [Table 3b]. There was alarmingly low sensitivity pattern of all Gram-negative isolates except Salmonella spp. in the blood to third generation cephalosporin's (40–55%). Among the beta-lactam/beta-lactamase inhibitor combination that is, (piperacillin and tazobactam [PIP + TAZ]) 78% of the E. Coli isolates were sensitive as compared to only 65% and 50% of Pseudomonas and Klebsiella, respectively. Among the carbapenems (imipenem/meropenem) most of the clinically significant isolates were sensitive to the tune of 90%. Only half of the Enterobacter and Acinetobacter species were sensitive to broad-spectrum antibiotic such as carbapenems. The sensitivity pattern of major Gram-positive organism was assuring with 100% sensitivity to commonly used antibiotics such as vancomycin/teicoplanin and linezolid.{Table 3a}{Table 3b}

Analysis of the isolates from the respiratory secretions is detailed in [Table 4a] and [Table 4b]. Colistin was the most effective antibiotic with almost 100% of various isolates sensitive to this drug. carbapenems were active for Klebsiella and E. coli (94–98%) sensitivity, but had a poor sensitivity of 65% for Pseudomonas and an alarming resistance to Acinetobacter species (20% sensitivity). There was poor sensitivity to third generation cephalosporins ranging from 50% to 60% for all the Gram-negative isolates. There was a variable activity for PIP + TAZ combination (65–67% for Pseudomonas, Enterobacter, and E. coli; 98% for Klebsiella). The aminoglycosides and fluoroquinolones had variable activity as detailed in [Table 4a]. The sensitivity pattern of Gram-positive respiratory isolates is detailed in [Table 4b]. Staphylococcus aureus showed low sensitivity to penicillin's and cephalosporin's (63% sensitivity) but were 100% sensitive to vancomycin/teicoplanin and linezolid. As per the past experience Enterococci, 75% were sensitive to vancomycin/teicoplanin but 100% isolates were sensitive to clindamycin and linezolid.{Table 4a}{Table 4b}

[Table 5] compares the patterns of resistance of the organisms isolated from blood and respiratory isolates. ESBL were most prevalent in respiratory secretions (72%) followed by 47% for blood isolates. Though very few pan resistant organisms were isolated but it was alarming to have 5% isolates in the blood that were resistant to all the available antibiotics. Among the Gram-positive organisms 25% respiratory isolates were vancomycin-resistant Enterococci (VRE) followed by 15% in blood. There was a very high degree of methicillin-resistant S. aureus with 35% of respiratory isolates showing resistance to methicillin and or cloxacillin.{Table 5}


There are various guidelines available at national and international levels regarding the management of febrile neutropenia. Adoption of these guidelines into an individual oncology unit is posed by challenges such as difference in the predominant pathogens, their sensitivity pattern and/or health care–associated economic conditions. Regardless of that, clinical vigilance and immediate treatment are the universal keys to managing neutropenic patients with fever and/or infection. Therefore, the audit and analysis of the microbiological isolates and their sensitivity is indispensable for an oncology unit.

Among all the isolates, the predominant isolates in our study was a Gram-negative organism (74.6%). Prabhash et al. have reported the similar experience from Mumbai [3] (Gram-negative organism 68.1% of blood cultures) and Karanwal et al. (Gram-negative organism 78% of the total isolates) from Ahmedabad.[4] This is contrary to the literature reported from developed countries where there are more incidences of Gram-positive isolates, which may be due to less instillation of central venous catheters and infrequent use of fluoroquinolone prophylaxis in India.

Among the Gram-negative isolates, the predominant organism in our study were E. Coli (23.5%) followed by Salmonella spp. (17.74%) and Klebsiella spp. 13.4%. There was a very low incidence of Pseudomonas isolated from the cultures at our center (6.7%). On review of the experience of other authors from India, the Pseudomonas is the predominant organism (30.3% from TMH, Mumbai) and (55.7% from AIIMS, Mumbai).[5] The above variation in this observation may be due to the inclusion of non neutropenia patient from surgical and radiation oncology subspecialty and more number of isolates from urine instead of blood. Among the Gram-positive isolates, S. aureus (34.3%) was the most common followed by Enterococcus spp. (29.2%). Similar incidence of S. aureus of (22%) have been reported in other studies from India.[3],[4],[5]

The pattern of resistance among all the isolates has been detailed in [Table 5]. Half of the blood isolates and 2/3 of respiratory isolates were ESBL producers and were resistant to empirically used third generation cephalosporins. Prabhash et al.[3] reported poor susceptibility of E. coli and Klebsiella pneumoniae to the third generation cephalosporins (18.9–22.6 and 25.7–28.6%, respectively). Saghir et al. from Pakistan also observed that 79% of bacterial isolates of Enterobacteriaceae were resistant against both fluoroquinolones and cephalosporins.[6] Jin et al.[7] from Singapore also reported that the majority of GNB isolated on initial blood cultures from patients with hematological diagnoses were resistant to the noncarbapenem first-line antibiotics ceftazidime (13 of 22 isolates, 59.1%). More challenging and alarming for our immune-compromised patients is the emergence of multidrug-resistant (carbapenem-resistant bacteria), which is as high as 13–15% in this study. The significantly higher incidence of carbapenem-resistant GNB (50% in Pseudomonas and 80% in Acinetobacter) has been reported by Ghosh et al. from AIIMS, Delhi.[8] This is a significant finding in the backdrop of formulating empirical therapy for immunocompromised patients in our population.

Among the Gram-positive organisms, 15% of the blood and urine isolates and 25% respiratory isolates were VRE. The impressive susceptibility of staphylococci to vancomycin and linezolid (100%) as observed by us have been reciprocated in many centers from South East Asia also, thus confirming that majority of morbidity and mortality in neutropenic patients is associated with Gram-negative septicemia.[7],[9]


To conclude we observed a high incidence of Gram-negative isolates with clinically significant resistance to first-line antibiotics such as cephalosporin's, PIP + TAZ and fluoroquinolones. We also expect that this report will be of great help to the clinician in starting empirical treatment for febrile neutropenia. These emerging resistance patterns call for the judicious use of antibiotics, surveillance of resistant patterns, and an active infection control policy within the oncology unit. It is of utmost importance for all the major oncology centers of India (government and private) to collaborate and provide a nationwide policy for management of neutropenic sepsis, which will lead to a standardized approach within and across institutions of the country.


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2Averbuch D, Orasch C, Cordonnier C, Livermore DM, Mikulska M, Viscoli C, et al. European guidelines for empirical antibacterial therapy for febrile neutropenic patients in the era of growing resistance: Summary of the 2011 4th European Conference on Infections in Leukemia. Haematologica 2013;98:1826-35.
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