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 Table of Contents  
Year : 2019  |  Volume : 21  |  Issue : 1  |  Page : 10-15

Five-year trend of bacterial isolates and their antibiotic resistance from automated BACTEC blood culture system from a rural medical college hospital in North Kerala, India: 2012–2016

1 Department of Microbiology, MES Medical College Hospital, Perinthalmanna, Kerala, India
2 Department of Quality, MES Medical College Hospital, Perinthalmanna, Kerala, India

Date of Web Publication12-Aug-2019

Correspondence Address:
Dr. Ramakrishna Pai Jakribettu
Associate Professor/Hospital Infection Control Officer, Department of Microbiology, MES Medical College, Perinthalmanna, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jacm.jacm_26_18

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INTRODUCTION: Blood stream infections (BSI) accounts for the most serious infection encountered in hospital. It has high rate of morbidity and mortality with high cost of treatment including high end antibiotics. Therefore, early detection, identification of the pathogens with their antibiogram is very important. With the advent of increasing antibiotic resistance, a close monitoring of change in the antibiotic resistance pattern is essential. Thus, the present study was undertaken to study the bacteriological profile with antibiogram of the aerobic pathogens isolated from the automated blood (BACTEC) culture system from 2012-2016.
MATERIALS AND METHODS: It was a retrospective study conducted at Clinical Microbiology Department, MES Medical College Hospital, Perinthalmanna. All the positive BACTEC blood culture samples from January 2012 to December 2016, of patients above 18 years of age, were included in the study.
RESULTS: During the study period of 5 years, out of 11,966 BACTEC samples, 932 ( 7.78%) were positive. The gram positive bacteria constituted for 539 (57.83%) compared to 393 (42.16%) Gram negative isolates. Staphylococcus aureus ( 41.41%) was the most common isolate among Gram positive and Escherichia coli (16.41%) among the gram negative isolate. During the study period 2012-2016, there was steady rise in the Methicillin Resistant Staphylococcus aureus (MRSA) from 0.86%, 1.07%, 2.25%, 3.76%, 6.12%. Among the Gram negative isolates, the resistance for 3rd Cephalosporins, Fluoroquinolones, β lactum- β lactum inhibitors, Carbapenems have also increased.
CONCLUSION: In the present study, we have observed the rise in multidrug resistant isolates especially MRSA, Escherichia coli, Acinetobacter species. This helped us to update the empirical antibacterial regime for the patient with suspected sepsis.

Keywords: Antimicrobial resistance, automated blood culture, multi - drug resistance, sepsis, trend

How to cite this article:
Ahmed SM, Jakribettu RP, Rajeevan S, George A, K Mariyam MA, Rao S V. Five-year trend of bacterial isolates and their antibiotic resistance from automated BACTEC blood culture system from a rural medical college hospital in North Kerala, India: 2012–2016. J Acad Clin Microbiol 2019;21:10-5

How to cite this URL:
Ahmed SM, Jakribettu RP, Rajeevan S, George A, K Mariyam MA, Rao S V. Five-year trend of bacterial isolates and their antibiotic resistance from automated BACTEC blood culture system from a rural medical college hospital in North Kerala, India: 2012–2016. J Acad Clin Microbiol [serial online] 2019 [cited 2022 Dec 8];21:10-5. Available from: https://www.jacmjournal.org/text.asp?2019/21/1/10/264250

  Introduction Top

Sepsis is a systemic, deleterious host response to infection, leading to septic shock and multiorgan dysfunction syndrome.[1] Despite the development in medical field, sepsis is a major cause for morbidity and mortality, worldwide.[2] Even in high-income countries such as the USA, the incidence of sepsis cases is around 750,000 annually with a mortality of around 30%.[3] In Indian scenario, sepsis is very common in intensive care units (ICU's) with high mortality rate.[4] It in turn increases the total cost of treatment including high-end antibiotic therapy and life-supporting treatment.[5]

Therefore, early detection and identification of pathogens with their antibiogram is very important. Even though bacteraemia is detected in around 20% of the critically ill sepsis patients, blood culture plays a major role in the early diagnosis of sepsis and thus the empirical therapy.[6]

A delay in administering appropriate antibiotic in cases of sepsis can cause increased rate of mortality. Inappropriate empirical antimicrobial therapy can lead to mortality rate to as high as 75%,[7] and for delay in every hour in administration of appropriate antimicrobial therapy, there is 8% decrease in survival rate.[8]

With the emergence of the multidrug-resistant pathogens in community as well as in hospital setup, the empirical antibiotic choice needs to be revised on regular basis, depending on the epidemiology of the selected healthcare setup. Inability to suspect multidrug-resistant pathogens can be one of the most important factors for inappropriate initial empirical antimicrobial therapy.[9]

A close monitoring of the trend of pathogens causing sepsis and their antimicrobial resistance (AMR) pattern needs to be done at least annually for appropriate prescription of empirical antimicrobial therapy. Hence, this study was undertaken to monitor the trend of the aerobic bacteria causing sepsis and their antibiogram which were isolated from automated blood culture system from 2012 to 2016.

  Materials and Methods Top

A retrospective study was conducted in the Department of Clinical Microbiology, of 570-bedded multi-speciality medical college Hospital in North Kerala, after clearance from the Institutional Ethics Committee (No.IEC/MES/27/2017).

All the positive aerobic blood culture samples of admitted patients above the age of 18 years, who were suspected of sepsis from January 2012 to December 2016 were included in the study.

The automated blood culture system, i.e., BACTEC 9050 (Becton Dickinson Microbiology Systems, Sparks, MD, USA) was used. As the blood culture bottles were flagged positive in the system, the sample was subjected to Gram's staining, and accordingly, they were subcultured on blood agar and Mac Conkey's agar. The identification of the pathogens was done by standard biochemical reactions manually, and antibiotic susceptibility testing was done by the Kirby–Bauer's disc diffusion method according to CLSI guidelines.[10] The quality control of the disc was tested by  Escherichia More Details coli ATCC 25922 and Staphylococcus aureus ATCC 25923.

The demographic details of the patients, the pathogen isolated and the antibiotic susceptibility pattern were collected; the repeat isolates were excluded. All samples were stratified by year, gender, ward and age wise (18–30, 31–45, 46–60 and >60 years). The year-wise cumulative antibacterial resistance rate was calculated for Gram-positive and Gram-negative organisms separately and analysed for change in the rate. The collected data were entered into Microsoft Excel and were analysed by percentage and Chi-square test, and P < 0.05 was considered as statistically significant.

  Results Top

Demographic details

During the study period from January 2012 to December 2016, a total of 1,937,417 patients registered on outpatient basis and 181,954 patients got admitted, with an average bed occupancy rate of 83%. During this period, a total of 11,966 BACTEC samples were received in our laboratory. Of these, 930 (7.77%) were positive with range of positivity from 6.79% (2013) to 9.13% (2012). Among the positive cultures, 52% were from male patients and 48% from female patients. There was no much difference in the ward-wise distribution of the positive samples; both ICU and general wards showed equal distribution. The geriatric patients, i.e., above 61 years constituted for around 50% of the positive samples, as these constituted the major sample size of around 60% of the sample, and least was noticed among 18–30 years, i.e., 11.29%. The details of positive samples with regard to gender, ward and age group are given in detail in [Table 1].
Table 1: Demographic details of the blood sample received during the study period (2012-2016)

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Distribution of pathogen isolated

Among the 930 pathogens isolated, the Gram-positive bacteria constituted for 539 (57.83%), of which S. aureus (386, 41.5%) was the most common isolate [Table 2]. Methicillin-resistant S. aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MRCoNS) accounted for 131 (14% of total isolates and 33.9% of total S. aureus) and 52 (5.6% of total isolates and 41.26% of total CoNS), respectively [Table 3]. During the study period 2012–2016, there was a steady rise in the MRSA from 7.2% to 23.26% among the total S. aureus isolates [Table 3]. There was an increasing trend of MRSA isolation as shown in [Figure 1]. The isolation of CoNS has reduced from 18.94% to 9.79% of the total isolates. Meanwhile, Enterococcus species has been increasingly isolated in the later years up to 4.51% in 2016 [Table 4].
Table 2: Distribution of pathogen isolated during the study period (2012-2016)

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Table 3: Year-wise isolation rate of methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative Staphylococcus

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Figure 1: Trend in methicillin-resistant Staphylococcus aureus isolation

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Table 4: Year-wise distribution of the pathogens isolated from the blood during the study period (in percentage)

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The Gram-negative isolates accounted for 393 (42.16%); E. coli (153, 16.41%) was the most common isolate. Among the coli forms, Klebsiella spp. 67 (7.19%), Citrobacter spp. and  Salmonella More Details spp. 27 (2.9%) each were isolated. The non-fermenters accounted for 10% of all isolates, Acinetobacter spp. (56, 6.01%) and Pseudomonas spp. (39, 4.18%). There was a steady rise in the isolation of Acinetobacter spp. from 4.55% to 6.97%, which was of concern [Table 4].

Antimicrobial resistance pattern

Among the Gram-negative isolates, there was a steady rise in resistance for third-generation Cephalosporins (3GC), Aminoglycoside, β lactam-β lactamase inhibitors and Carbapenems. The resistance for Ceftriaxone has increased from 58% to 69%. Similarly, Amikacin was resistance to only 9% of isolates in 2012, has risen to 23% in 2016. The beta lactam-beta lactamase inhibitor (Piperacillin Tazobactum) resistance has increased from 15% to 42%. There was no resistance observed for Imipenem in the first three years, but later years showed emergence of resistance to 8% in 2016 [Table 5].
Table 5: Year-wise overall resistance pattern of Gram-negative pathogens (in percentage)

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The Gram-positive cocci showed an increase in resistance to Amoxyclav, Ceftriaxone, Cefoxitin, Ciprofloxacin, Erythromycin and Clindamycin. Ceftriaxone, which is the preferred antibiotic for empirical therapy for sepsis, showed raising resistance from 12% to 70% during the study period. Cefoxitin, a surrogate marker for Methicillin resistance in Staphylococcus, showed a steep rise from 11% to 70% [Table 6]. During the study period, we have not encountered any resistance to Vancomycin, Linezolid and Teicoplanin. We have observed decrease in resistance to Amikacin over five years in both MRSA and MSSA isolated [Table 6].
Table 6: Year-wise overall resistance pattern of Gram-positive pathogens (in percentage)

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When the individual pathogen was analysed, we observed that the Acinetobacter spp. has emerged as a multidrug-resistant pathogen, with increasing resistance to Meropenem, Piperacillin-Tazobactam and Amikacin to 23.5%, 94% and 35.3%, respectively. Similar, trend was observed in E. coli and Klebsiella sp. with increased resistance to these three drugs [Table 7]. The significant rise in resistance (P < 0.05) was seen for Piperacillin-Tazobactam alone, Meropenem alone and both, in Klebsiella sp., E. coli and Acinetobacter spp., respectively [Table 7].
Table 7: Year-wise resistance pattern was common pathogens isolated in blood, 2012-2016

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  Discussion Top

With the rising AMR at alarming rate and availability of limited higher antibiotics for these MDR pathogens, there is a need to formulate an antibiotic policy and followed at each and every tertiary care centre. The initial antimicrobial therapy when administered inappropriately, increases the mortality, increases length of stay and eventually, increases the financial burden on the patient.[11] We formulated antibiotic policy for the patient suspected with sepsis using this data. It was observed that geriatric patients were positive for blood culture compared to younger population, which was contradictory to a Pan India study.[5] We have encountered Gram-positive pathogen, especially Methicillin-sensitive S. aureus was most common, when compared to others studies in India.[4],[5] The trend of isolation of MSSA has reduced, but there was a steady rise in MRSA in the number of cases with sepsis. This is of concern, as it requires longer antibacterial therapy with Vancomycin, which is nephrotoxic and expensive. We were fortunate not to isolate Vancomycin-resistant Enterococcus or Vancomycin-resistant S. aureus (VRSA) in our hospital during the study period.

Among the Gram-negative bacteria, E. coli was the most common, which were in concurrence with various other studies.[5] With regard to Salmonella sp. isolation, we had only 2.9% when compared to other studies.[12] There was a marginal rise in MDR Acinetobacter spp. incidence from 4.55% to 6.97% in the five-year period. It is very important as mortality is very high in patients with Acinetobacter spp. bacteraemia, due to availability of very few high-end antimicrobials for therapy. We have seen upward trend in resistance among most of the antimicrobials in Gram-negative bacteria, except for Gentamicin and Ciprofloxacin. This may be due to reduced use of Gentamicin as an empirical therapy when compared to other higher antimicrobials. Among the 3GC, Ceftriaxone which was used for most of the patients empirically has now reached a resistance rate of 69% in 2016. Due to emergence of extended-spectrum beta-lactamase producers, the resistance to 3GC has been reported from various parts of the world.[13],[14],[15] The beta lactam-beta-lactamase inhibitor combination such as Piperacillin-Tazobactam, which is used for most of the patients with sepsis, has reached the resistance rate of 42% at the end of the study period. Carbapenem resistance was not observed in the initial years, but we observed a resistance of 5% and 8% in 2015 and 2016, respectively. Even though the Carbapenem resistance is less compared to other studies,[5] increasing trend is a concern. The resistance to Carbapenem may be due to production of the enzymes such as Carbapenemases, which is seen worldwide.[16] In India, metallo-β-lactamases (MBL) are the major reason for Carbapenem resistance, especially in nosocomial infections;[17] we have proposed that the screening of MBL has to be done routinely for all Carbapenem-resistant isolates in our centre.

As this is a single-centric retrospective study, there are many limitations; the result of the study needs to be validated by conducting a multicentric study. However, this study has helped us to formulate an antibiotic policy for the patients admitted with sepsis. As this was a retrospective study, we were not able to collect the clinical data of the patients, empirical antibacterial therapy, length of stay in ICU and hospital and outcome of the treatment. Cases could not be stratified as hospital acquired or community acquired.

  Conclusion Top

In this study, we have observed that the geriatric patients are more vulnerable for sepsis. The increasing resistance rate for the drugs which are recommended as empirical therapy for sepsis, especially Meropenem, Piperacillin-Tazobactam and Amikacin, will lead to therapeutic failure. Hence, we conclude that regular monitoring of the resistance pattern of pathogens isolated in sepsis is required to decide the appropriate drug for initial antimicrobial therapy, which plays a major role in the outcome of the treatment. The best method is to prevent the spread of these pathogens in the hospital. As only few drugs are available for use against these multidrug resistance pathogens, antibiotic stewardship programme needs to be implemented seriously in healthcare setup.


We thank Dr. SudhirPrabhu H, Associate Professor, Department of Community Medicine, Fr Muller Medical College, Mangalore, for his support with statistics.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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Chatterjee S, Bhattacharya M, Todi SK. Epidemiology of Adult-population sepsis in India: A single center 5 year experience. Indian J Crit Care Med 2017;21:573-7.  Back to cited text no. 4
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  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]

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