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ORIGINAL ARTICLE
Year : 2020  |  Volume : 9  |  Issue : 1  |  Page : 25-30

A study of microbiological profile and its antimicrobial susceptibility patterns related to central line-associated bloodstream infections in respiratory intensive care unit in a tertiary care hospital


1 Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India
2 Department of Anaesthesia, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India
3 Department of Emergency Medicine, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India

Date of Submission30-Jan-2019
Date of Decision08-Feb-2020
Date of Acceptance08-Feb-2020
Date of Web Publication2-Jun-2020

Correspondence Address:
Krishna Kanchan Sharma
Professor and Head, Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Alipiri Road, Tirupati 517 507, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JCSR.JCSR_18_19

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  Abstract 


Background: Complications associated with central venous catheter central line central line-associated bloodstream infections (CLABSIs).
Methods: We prospective by studied the microbiological profile and antimicrobial susceptibility patterns of isolated bacteria from CLABSIs in respiratory intensive care unit at our a tertiary care teaching hospital in Tirupati, Andhra Pradesh.
Results: Colonisers were isolated from 110 of the 288 samples without any growth in blood cultures from among 288 samples that were submitted with a clinical suspicion of sepsis from patients with eligible central line. Among these, Staphylococcus aureus was the predominant coloniser. Seventy-four were blood culture positive, of which 36 showed other sources of infection. In our study, CLABSI rate was 12.9/1000 catheterised days. Among these culture positives, predominant isolate was S. aureus, followed by Staphylococcus hominis, Acinetobacter, Klebsiella and Escherichia coli. All the S. aureus strains were sensitive to linezolid, tetracycline and vancomycin. Among Gram-negative organisms, Acinetobacter baumannii and E. coli strains were 100% sensitive to polymyxin B and tigecycline. In our study, we have observed carbapenem resistance in E. coli and A. baumannii, which is alarming. Methicillin-resistant S. aureus accounted for 71.4% of S. aureus CLABSIs. All A. baumannii (n = 6), Klebsiella (n = 4) and E. coli (n = 4) isolates were extended spectrum beta-lactamase producers.
Conclusions: Strict implementation of insertion and maintenance bundle care of the central lines is mandatory to prevent colonisation.

Keywords: Central venous catheters, intensive care units, sepsis


How to cite this article:
Ujesh S N, Jayaprada R, Ramakrishna N, Sharma KK, Rao MH, Samantaray A, Madhusudhan M. A study of microbiological profile and its antimicrobial susceptibility patterns related to central line-associated bloodstream infections in respiratory intensive care unit in a tertiary care hospital. J Clin Sci Res 2020;9:25-30

How to cite this URL:
Ujesh S N, Jayaprada R, Ramakrishna N, Sharma KK, Rao MH, Samantaray A, Madhusudhan M. A study of microbiological profile and its antimicrobial susceptibility patterns related to central line-associated bloodstream infections in respiratory intensive care unit in a tertiary care hospital. J Clin Sci Res [serial online] 2020 [cited 2020 Aug 15];9:25-30. Available from: http://www.jcsr.co.in/text.asp?2020/9/1/25/285710




  Introduction Top


Central venous catheters (CVCs) are integral to the modern practices and are inserted in critically ill patients. Its inevitable use makes patients prone to complications which include central line-associated bloodstream infections (CLABSIs). The problem of CLABSIs has gained increasing attention in recent years.[1] There is a significant gap on the CLABSIs burden globally, regionally and locally.[2]

The organisms associated with CLABSI are usually the normal resident flora of the skin at the insertion site. Gram-positive cocci and coagulase-negative staphylococci are the leading bacteria cultured from catheters, followed by Gram-negative organisms. Microbial biofilm may pose a public health problem for persons requiring indwelling medical devices.[3]

CLABSIs occurring in the respiratory intensive care unit (RICU) are common, expensive and potentially lethal. The prevention of CLABSI includes development of records, guidelines, bundle care, maximum sterile barrier, use of 2% chlorhexidine, early catheter removal, use of antimicrobial catheters and antimicrobial catheter lock solution.[4] The objective of the present study was to determine the microbiological profile and antimicrobial susceptibility patterns of isolated bacteria from CLABSIs in RICU.


  Material and Methods Top


This prospective study which was carried out on CLABSI and related samples (blood cultures and catheter tip cultures) submitted to microbiology laboratory from inpatients in RICU at our tertiary care hospital in Tirupati, during 1-year period from March 2017 to March 2018. The study was conducted after obtaining clearance from institutional Ethics Committee. Central lines were inserted aseptically as per standard protocol. Catheter tips were processed using roll and vortex plate methods. Under aseptic precautions, 4 cm segment of the tip was cut and placed in a sterile universal container (Tarson, India). It was transported immediately so as to prevent drying and processed within 2 h of collection.

Blood from at least two separate blood draws was collected on the same or consecutive calendar days under strict asepsis. Catheter tip samples were processed for both semi-quantitative method (roll-plate) and quantitative method (vortex) [Figure 1].[5] According to it, isolation of >15 colony-forming unit (CFU)/mL can be considered as significant for semiquantitative method and >100 CFU/mL for quantitative method. Simultaneously, blood cultures were also processed. Blood culture samples were collected aseptically and then processed as per standard technique.[6] In positive cultures, bacterial colonies were processed and identified. Phenotypic identification of pathogens was carried out by a battery of biochemical reactions depending on the organism. Growth in MacConkey agar was identified as lactose fermenting (LF) and non-lactose fermenting (NLF) colonies. LF colonies were identified, based on motility, catalase test, nitrate reduction, methyl red test, Voges–Proskauer test, production of indole, hydrogen sulphide (H2S), urease, citrate utilisation and sugar fermentation tests.
Figure 1: Quantitative and semi-quantitative identification of central line-associated bloodstream infections, MacConkey agar showing growth of mucoid, lactose fermenter colonies

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Bacteria-producing NLF colonies were identified based on oxidase production, catalase production and reduction of nitrate to nitrite. Further speciation depended on motility, fermentative/oxidative metabolism of sugars, phenylalanine deaminase test and fermentation of a battery of sugars, production of indole, H2S, urease, methyl red test, Voges–Proskauer test, citrate utilisation, decarboxylation of lysine, arginine and ornithine.

Gram-positive cocci morphologically resembling staphylococci were identified by modified oxidase test, coagulase test and novobiocin sensitivity test. Suspected Enterococcus showing magenta-coloured colonies on MacConkey agar were identified by bile esculin test, growth in the presence of 6.5% sodium chloride and fermentation of sugars in peptone water sugar media.

Antimicrobial sensitivity testing for the isolates was done on Muller-Hinton Agar (MHA) by Kirby-Bauer's disc diffusion method as per the Clinical and Laboratory Standards Institute (CLSI) guidelines 2016.[7] Commercially available discs (Hi-Media) were used. Informed consent was obtained from all the study participants

First-lineampicillin (10 μg), amoxicillin-clavulanate (20/10 μg), cefotaxime (30 μg), cefoperazone-sulbactam (75/10 μg), imipenem (10 μg), ciprofloxacin (5 μg), amikacin (30μg), gentamicin (10μg), piperacillin-tazobactam (100/10 μg) and cotrimoxazole (25 μg). Second-line cefepime (30 μg), cefoxitin (30 μg), ceftazidime (30 μg), chloramphenicol (30 μg), tetracycline (30 μg), netilmicin (30 μg), meropenem (10 μg), polymyxin B (300 U), and tigecycline (15 μg).

First-lineampicillin, amoxicillin-clavulanate and cotrimoxazole were replaced with ceftazidime (30 μg), netilmicin (30 μg) and polymyxin B (300 U). Second line: aztreonam (30 μg), carbenicillin (100 μg), cefepime (30 μg), meropenem (10 μg) and tobramycin (10 μg). The media and antibiotic discs were procured from HiMedia (India).

For polymyxin B, no CLSI guidelines are available for interpretation of disc diffusion technique as regards Enterobacteriaceae and Acinetobacter spp; and for these isolates, other recommendation[8] was adopted. Methicillin resistance in Staphylococcus aureus (MRSA) was tested using MHA with cefoxitin disc (30 μg) by Kirby-Bauer disc diffusion method as per CLSI guidelines 2016.[7]

The CLABSI rate was calculated by using the following formula:



Statistical analysis

Statistical analysis was done using Microsoft Excel 2007 (Microsoft Corp, Redmond, WA, USA) and SPSS version 20 (IBM Corp, Somers, NY, USA). Frequencies and percentages were calculated. The association for contaminants, pathogens and isolated organism to that of infection was calculated by using Chi-square test. P < 0.05 was considered statistically significant.


  Results Top


Categorization of patients on the basis of CLABSI is shown in [Table 1]. A total of 288 tip cultures were received by the laboratory from RICU patients with a clinical diagnosis of sepsis following central venous catheterisation. Of the 288 patients, a total of 110 catheter tips were colonised. Among the colonised catheters, Gram-positive cocci were most common, followed by S. hemolyticus, Klebsiella, Acinetobacter, Enterococcus, Pseudomonas and Escherichia coli.
Table 1: Categorisation of patients on the basis of central line-associated bloodstream infections

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Of the 74 bloodstream infections, 38 were diagnosed as CLABSI with a rate of 12.9/1000 line days, and S. aureus was the predominant pathogen, followed by S. haemolyticus, Acinetobacter, Klebsiella and E. coli spp. Results of antibiotic susceptibility testing of these CLABSI isolates are shown in [Table 2] and [Table 3].
Table 2: Antibiotic sensitivity pattern of Gram-positive isolates in central line-associated bloodstream infections cases

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Table 3: Antibiotic sensitivity pattern of Gram-negative isolates in central line-associated bloodstream infection cases

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Among 14 isolates of S. aureus, 10 (71.42%) were MRSA, and among 10 coagulase-negative Staphylococcus, 8 (80%) were methicillin-resistant coagulase-negative Staphylococcus species (MRCoNS). Among 14 Gram-negative isolates, 8 (57%) showed resistance to imipenem. All Gram-negative bacteria isolated showed extended spectrum beta-lactamase (ESBL) production [Table 4].
Table 4: Distribution of MRSA, MRCoNS, ESBL in patients with central line-associated bloodstream infection

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The most common underlying condition among the CLABSI cases (n=38) was found to be renal failure (57.8%), followed by chronic obstructive pulmonary disease, acute respiratory distress syndrome, Guillian-Barre (GB) syndrome, cerebrovascular accident and poisoning [Table 5]. Two of the 38 CLABSI cases (5.3%) died; one due to renal failure, sepsis with multi-organ dysfunction syndrome (MODS) and the other due to GB syndrome [Table 6]. Mortality among jugular vein CLABSI was 0.7%. Mortality due to CLABSI with subclavian/femoral line catheterisation was 0 [Table 7].
Table 5: Central line-associated bloodstream infections in various clinical conditions

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Table 6: Mortality in patients with central line-associated bloodstream infection cases

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Table 7: Mortality in CLABSI in relation to central line catheters

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  Discussion Top


In the modern health-care delivery, CVC insertion has become an integral part of treatment modality in all intensive care units (ICU). Their use is associated with the risk of bloodstream infection.

In our study the most common age group was 51–60 years. Of these, 110 (38.2%) showed colonisation. The incidence of catheter colonisation of various other studies ranged from 31.6% - 76%. The microorganisms most frequently colonising the catheters were S. aureus (18.2%), followed by S.haemolyticus, Klebsiella, Acinetobacter, Enterococcus, Pseudomonas and E. coli. Gram-positive cocci were the predominant colonisers of CVC, as reported in other studies.[9],[10]

Among the 288 cases, the most common site of catheter insertion was subclavian catheter (49%), followed by jugular catheter (34%) and femoral catheter (17%). Out of the 38 CLABSI, higher percentage of infection was observed in patients with internal jugular catheter (63%), followed by subclavian catheter (26%) and femoral catheter (11%). The incidence of CLABSI reported by Randolph et al.[11] was as higher in internal jugular group than subclavian group, which is similar to our study. In another study[12] the incidence of CLABSI in internal jugular vein was 6.8%, femoral vein was 6.5% and subclavian vein was 24.6%; our observations were similar. These differences may be attributed mainly to differential preference of central cannulation sites which varied across different institute protocols.

In our study, CLABSI rate per 1000 catheter days was 12.9, which is correlating with the WHO (low-resource countries) benchmark of 12.2 (10.5–13.9).[13] In comparison, the National Nosocomial Infections Surveillance System report documented it to be between 1.8 and 5.2 per 1000 catheter days. CLABSI rate (/100 catheter days) in different studies were reported to be 14.6,[9] 18.8,[14] and 20.6[15] which are higher than that documented in the present study. Two other studies[16],[17] had shown CLABSI of 2.7/1000 catheter days and 4.0/1000 central line days, respectively, which is not in agreement with our study because these studies were conducted in countries having high socio-economic status.

In our study, the maximum CLABSI rate was observed in the age group of 41–50 years (37%), followed by the age group of 61–70 years (26%). A study by Patil et al.[18] reported 29.62% of rate of CLABSI in patients above the age of 60 years and 25.92% rate in patients who were between the ages of 41 and 50 years.

Gram-positive organisms were the most common isolates in our study (63%), which is similar to that reported in other studies.[1],[19],[20] Similarly, in another study[21]S. aureus and coagulase-negative Staphylococcus accounted for majority of the CLABSI episodes.

Out of the total 38 isolates, 24 were Gram-positive cocci (S. aureus 14 and coagulase-negative staphylococci 10). Out of 14 S. aureus isolates, 10 were MRSA and 4 were methicillin-sensitive Staphylococcus aureus. Among ten CoNS, eight were MRCoNS. Both the MRSA and MRCoNS isolates were sensitive to linezolid and vancomycin. Similar findings were reported in other studies.[18],[19],[20] Both the MRSA and MRCoNS isolates were sensitive to linezolid and vancomycin.

Fourteen Gram-negative bacilli were isolated, which included Klebsiella (n = 4), Acinetobacter baumannii (n = 6) and E. coli (n = 4). Four strains (67%) of A. baumannii, isolated from CLABSI, were sensitive to amikacin, chloramphenicol, imipenem, piperacillin-tazobactam and cefoperazone-sulbactam, and all 6 (100%) were sensitive to polymyxin B and tigecycline. Only two (33%) showed sensitivity to ciprofloxacin, cotrimoxazole, meropenem, netilmicin and tetracycline. In other studies,[19],[20] multidrug-resistant (MDR) strains of A. baumannii were isolated from CLABSI.

All the four strains of Klebsiella isolates were sensitive to amikacin, meropenem, piperacillin-tazobactam, polymyxin B, levofloxacin and ertapenem. Two of these were resistant to imipenem, cefoperazone-sulbactam and tetracycline. Our observations are similar to that reported in a study[18] where all Klebsiella pneumoniae were found to be sensitive to amikacin. However, in another study that the K. pneumoniae isolates were resistant to all the antibiotics except amikacin and ciprofloxacin, which is in discordance with our study.[18]

All E. coli (100%) isolates were resistant to cefoperazone-sulbactam, imipenem, piperacillin-tazobactam and netilmicin and were sensitive to meropenem, tetracycline and polymyxin B.

In our study, all Acinetobacter, E. coli and Klebsiella isolates were ESBL producers with a high prevalence of MDR, which is similar to other studies.[1],[17],[20] Three studies[18],[19],[20] reported similar MDR strains of Acinetobacter and Klebsiella from CLABSI. We observed carbapenem resistance in E. coli (50%) and A. baumannii (33.3%); no carbapenem-resistant K. pneumonia were isolated. However, a higher occurrence of carbapenem-resistant isolates of Klebsiella (34%) was reported, in another study.[22] Among staphylococcal isolates, MRSA constituted 71.4% and MRCoNS 80%.

Twenty of the 288 cases (7%) died; of these 16 had renal failure and sepsis, two had superior mesenteric ischaemia and dry gangrene and two others had GB syndrome. Out of 38 with CLABSI, two died; one hadrenal failure and sepsis with MODS and other had GB syndrome.

CLABSI is the essential impediment of central venous access in ICUs. Active intervention of the clinician is required to ascertain the signs of sepsis in patients at earliest and to send properly collected samples at appropriate time for an early diagnosis, in turn, decreasing the morbidity and mortality associated with CLABSIs. Catheter colonisation has an important role in the development of CLABSI that may lead to septicaemia and multiorgan failure. Insertion of the central line under aseptic precautions and scrupulous sterile care of the after wound and catheter hub has significant impact in reducing the CLABSI in ICUs. Adequate teaching and education of medical and nursing staff and strict implementation of insertion and maintenance bundle care of the central lines is mandatory to prevent colonisation. Additional training and education of all staff involved in insertion and subsequent handling of central lines, as well as monitoring the use of guidelines, may have an effect on further decreasing the infection rates. Simple hand hygiene is the best steward in fighting against the transmission of MDR organisms among patients with central lines.



Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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