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Table of Contents
ORIGINAL ARTICLE
Year : 2020  |  Volume : 9  |  Issue : 2  |  Page : 101-104

A study of microbiome and its antimicrobial susceptibility patterns among central line-associated bloodstream infections


Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India

Date of Submission21-Mar-2019
Date of Decision31-Mar-2020
Date of Acceptance02-Apr-2020
Date of Web Publication4-Aug-2020

Correspondence Address:
Jayaprada Rangineni
Assistant Professor, Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Tirupathi, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JCSR.JCSR_34_19

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  Abstract 


Introduction: Central line-associated bloodstream infections (CLABSIs) are the most frequent cause of health-care-associated infections and significantly increase cost and hospital length of stay.
Methods: We retrospectively studied hospitalised patients having a central line access during the period 2016-2018, to study patients with CLABSI at our tertiary care hospital.
Results: Average CLABSI rate was 16.7 per 1000 central line days for 3 years. Most of the infections were caused by Staphylococcus aureus (18.9%), followed by non-fermentative Gram-negative bacilli (NFGNB) (16%), Klebsiella spp. (15.1%), Acinetobacter spp. (14.2%) and coagulase-negative Staphylococcus ( CoNS) (13.2%). A higher proportion of CLABSI was observed with femoral lines (59.7%), followed by jugular lines (35.8%) and subclavian lines (9.4%). This study showed multidrug-resistant pathogens as a causative agent of CLABSI.
Conclusion: CLABSI is a common entity, especially in intensive care unit settings. S. aureus, NFGNB, Klebsiella spp., Acinetobacter spp. and CoNS were the common pathogens isolated in our study. Strict implementation of CLABSI bundle care plays an important role to minimise the CLABSI rate.

Keywords: Central line-associated blood stream infections, central venous catheter, Gram-negative, Gram-positive, multidrug-resistant organisms


How to cite this article:
Sharabu Y, Ramakrishna N, Rangineni J, Sharma KK, Sanangula SV. A study of microbiome and its antimicrobial susceptibility patterns among central line-associated bloodstream infections. J Clin Sci Res 2020;9:101-4

How to cite this URL:
Sharabu Y, Ramakrishna N, Rangineni J, Sharma KK, Sanangula SV. A study of microbiome and its antimicrobial susceptibility patterns among central line-associated bloodstream infections. J Clin Sci Res [serial online] 2020 [cited 2020 Oct 31];9:101-4. Available from: https://www.jcsr.co.in/text.asp?2020/9/2/101/291373




  Introduction Top


Central line-associated bloodstream infections (CLABSI) are laboratory-confirmed bloodstream infections where an eligible bloodstream infection is recognised and an eligible central line is present on laboratory confirmed blood stream infections (LCBI) on date of event or the day before as per the Centers for Disease Control and Prevention (CDC) guidelines, 2018. It is one of the most frequent, expensive complications of central venous catheter (CVC), which is associated with morbidity and mortality. It also increases hospital stay and cost of hospitalisation.[1] CVCs are important in modern practices and inserted to critical patients for administration of fluids, medication, nutritional solutions and for haemodynamic monitoring.[2] These patients are more prone for iatrogenic infections. In high-resource countries, approximately 80,000 CLABSI cases occur in intensive care units (ICUs) every year.[3] In resource-limited countries, CLABSI rates are high due to poor maintenance of bundle care. Comparatively, CLABSI rates are high in developing countries. Incidence varies from country to country and among hospitals with in a country. This may be due to limited training and knowledge in infection prevention and control. Interventions regarding the insertion and maintenance of CVCs, such as, strict implementation of CLABSI insertion bundle (hand hygiene, following aseptic precautions when inserting lines and wearing of personal protective equipment) can result in a decline in the rate of CLABSI.[4] Coagulase-negative Staphylococcus (CoNS) associated with CLABSI are usually normal flora of skin at the insertion site and may lead to colonisation of central line. Changing of 2% chlorhexidine gauze dressings at least every 2 days or semipermeable dressings at least every 7 days is essential to decrease CLABSI rate.[5] Strategies such as antimicrobial/antiseptic-impregnated catheters and antiseptic-impregnated caps for access ports are also helpful in decreasing CLABSI rate.[5] Hence, the present study was planned to determine the microbiome and its antimicrobial susceptibility patterns among CLABSIs in a tertiary care teaching hospital.


  Material and Methods Top


This retrospective study was carried out done at our tertiary care teaching hospital from 2016 to 2018. All details regarding patients and central were collected from the records. All samples were processed as per the standard protocols. The semi-quantitative and quantitative methods were used for catheter tip culture.[6] Blood cultures were processed using BacT/alert automated system and conventional blood cultures. Antibiotic susceptibility testing was performed using Kirby–Bauer disc diffusion method as per the Clinical and Laboratory Standards Institute 2016 guidelines.

Diagnosis of CLABSI was made based on positive blood culture and as per old and new CDC guidelines 2016 and 2018. As per old guidelines, central line-associated blood stream infection (CLABSI) is defined as laboratory-confirmed bloodstream infection in a patient where the central line was in place for >2 calendar days (48 h) on the date of the event, with day of device placement being day 1. As per the new CDC guidelines 2018, CLABSI is defined as a LCBI where an eligible blood stream infection organism organism is identified and an eligible central line is present on the LCBI day of event or the day before.

Bundle care as per the above Protocol 1 and 2 has been implemented at our tertiary care teaching hospital from August 2017.

Statistical analysis

Data were entered into a structured proforma Variables are summarized as number (percent). CLABSI rate (/1000 central line days) was calculated. Device utilisation ratio was calculated as number of device days/number of patient days. “Device-days” are the total number of days of exposure to the device (central line, ventilator, or urinary catheter) during the selected time period. “Patient-days” are the total number of days that patients are in the ICU during the selected time period. Data analysis was carried out using Microsoft Excel version 16.0 (Microsoft Corporation, Richmond, USA).


  Results Top


During the study period, Out of 925 patients with central lines, 106 patients satisfied CLABSI criteria and were included in the study. The average CLABSI rate was 16.7/1000 line days (17.7% in 2016, 15.3% in 2017 and 13.2% in 2018), Device utilisation ratio for the years 2016, 2017 and 2018 was 17.9, 14.8 and 10.4, respectively [Table 1]. A higher proportion of CLABSI was observed with femoral (59.7%), followed by jugular (35.8%) and subclavian lines (9.4%) [Table 2].
Table 1: Year-wise distribution of CLABSI and device utilisation ratio

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Table 2: Distribution of central line-associated bloodstream infections among various central lines

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Culture positivity for S. aureus was 20 (18.9%), followed by non-fermentative Gram-negative bacilli (NFGNB) (n = 17; 16%), Klebsiella spp. (n = 16; 15.1%), Acinetobacter spp. (n = 15; 14.2%), CoNS (n = 14; 13.2%) and Pseudomonas spp. (n = 9; 8.5%) [Table 3]. Gram-negative resistance rate to third-generation cephalosporins was noted in 28/56 (50%) Gram-negative isolates. Multidrug resistance (MDR) (67.9%) was noted in 38/56 Gram-negative isolates. Among MDR organisms, NFGNB were 12 (70%), followed by Acinetobacter 10 (66.7%), Escherichia spp. 3 (60%), Klebsiella spp. 6 (37.5%) and Pseudomonas spp. 2 (22.2%). Among 56 Gram-negative bacilli, 17 were extended-spectrum beta-lactamase-producing organisms (ESBLs) contributing to 30.4%. ESBLs included 7 (41.2%) Acinetobacter spp., 5 (29.4%) Klebsiella spp., 3 (17.7%) Escherichia spp., 1 (5.9%) NFGNB and 1 (5.9%) Pseudomonas. Of the 56 Gram-negative bacilli, 14 (25%) were resistant to imipenem. Carbapenem resistance was noted in 7/16 (43.8%) Klebsiella.
Table 3: Distribution of various organisms (n=106) contributing to central line-associated bloodstream infections

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Methicillin resistance was noted in 18 Staphylococcus spp. (52.9%) out of 34 Staphylococcus spp. Methicillin-resistant S. aureus (MRSA) were 12 (60%) and 6 (42.9%) were MRCoNS. Four (8.7%) cases were linezolid resistant among staphylococcus species, but all were sensitive to vancomycin. Among staphylococcus isolated, 50% inducible clindamycin resistance was observed in S. aureus and 42.1% of CoNS were inducible clindamycin resistant. No vancomycin-resistant Staphylococcus (VRSA) organisms was observed in our study.

Majority of the study patients were admitted in nephrology department (61.7%) and the remaining 38.3% were distributed among other departments [Table 4].
Table 4: Categorisation of CLABSI (n=106) among various wards

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  Discussion Top


In our study, average CLABSI was 16.7/1000 central line days for 3 years. For low-resource countries like India, bench mark for CLABSI ranged from 10.5/1000 to 13.9/1000 line days.[5] Decrease in CLABSI rate from 2017 to 2018 was achieved by implementation of bundle care. To maintain CLABSI rate below the bench mark, strengthening of the bundle care along with standard precautions are essential. In another study[7] CLABSI rate 8.26 per 1000 line days was reported, which was less than that observed in our study. Occurrence of CLABSI was reported to be 3.73/1000 central line days in a study from Meyer Children's University Hospital, Florence, Italy.[8] In another study (2015-2016),[1] occurrence of CLABSI was 3.69/1000 central line days which was less than what we had reported. In our study, the most common indication for central line insertion was haemodialysis (60.6%), followed by infusion of intravenous fluids, medications and haemodynamic monitoring. Majority of the study patients were admitted in nephrology department (61.7%) [Table 4]. Similar results were reported in another study.[9] In a study from Michigan, CLABSI was found to occur in 2.7/1000 central line days and this figure is less than that reported in our study. The frequency of developing bloodstream infection was found to be the highest for the route of insertion being femoral vein, followed by jugular vein and least for subclavian vein. Another study[7] showed highest positive infection rate in jugular tip insertion. Most studies[9],[10],[11],[12],[13],[14] had focussed on intensive care unit patients The common microorganisms isolated in our study were S. aureus, followed by NFGNB,Acinetobacter spp., Enterobacteriaceae (K.pneumoniae,Escherichia coli) and CoNS. Gram-negative resistance rate to third-generation cephalosporins was noted in 28 (50%) Gram-negative organisms. Carbapenem resistance noted in Klebsiella was 7 out of 16 (43.8%). In another study[15] from Italy, Gram-negative resistance rate to third-generation cephalosporins was reported to be 30%–56%, and carbapenem-resistant Klebsiella 34% in invasive infections from Italy.[15] Our observations were similar to that reported in this study[15] in Gram-negative resistance rate to third-generation cephalosporins, but carbapenem resistance in Klebsiella was high. Out of 106 isolates, four were identified as Candida species. Among these four isolates, two each were Candidaalbicans and Candidanon-albicans. All were sensitive to fluconazole, voriconazole and amphotericin B. Comparing the prevalence rate of CLABSI between studies is challenging because of variations in study groups and setting, type of catheter, insertion technique and maintenance bundles. In addition, the case definition of CLABSI differs between studies, which might lead to variations in the prevalence rate of CLABSI.[16]

In our study, out of 106 isolates, 52.8% were Gram-negative organisms and the remaining 47.2% were attributed to Gram-positive organisms. Among Gram-negative bacilli, 17 (30.4%) organisms were ESBL-producing Gram-negative bacilli and 49 (87.5%) were MDR organisms. Among all 56 Gram-negative bacilli, 14 (25%) were resistant to imipenem. Methicillin resistance was observed in 18 (52.9%) out of 34 Staphylococcus spp. MRSA were 12 (60%) and 6 (42.9%) were MRCoNS. Four (8.7%) cases were linezolid resistant among Staphylococcus species, but all were sensitive to vancomycin. Among Staphylococcus isolated, 50% inducible clindamycin resistance was observed in S. aureus and 42.1% of CoNS were inducible clindamycin resistant. No VRSA organisms was observed in our study.

Insertion of CVCs provides access route through which these bacteria could migrate to the bloodstream to cause widely disseminated bloodstream infection. Strict implementation of insertion and maintenance bundles (Protocol 1 and Protocol 2) were capable of reducing the direct exposure of the bloodstream to skin commensals such as CONS, thereby reducing the overall burden of CLABSI.

After implementation of bundle care from August 2017, CLABSI rate has been lowered in 2018. Key principles undrrlying the bundle, such as, observing for signs of inflammation at insertion site of central line, removing the CVCs when central line is not in use, choosing the best insertion site based on individual patient characteristics all help in reducing CLABSI. In order to ensure that the reduction in CLABSI can be attributed entirely to the implementation of quality improvement and bundle processes, an ongoing audit at regular intervals is suggested.

CLABSI is best prevented rather than cured because of high mortality rates associated with central line-associated bloodstream infections. Strict adherence to standard precautions is needed in the intensive care unit during the insertion and maintenance of central lines to reduce CLABSI.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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