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 Table of Contents  
ORIGINAL RESEARCH REPORT
Year : 2015  |  Volume : 12  |  Issue : 1  |  Page : 51-56

Importance of medium time in case of device-associated infection


1 Department of Pathology and Microbiology, The Institute of Post-Graduate Medical Education and Research, Kolkata, West Bengal, India
2 Department of Microbiology, NRS Medical College, Kolkata, India

Date of Web Publication14-Jul-2015

Correspondence Address:
Dr. Angshuman Jana
Haldia, Purba Medinipore - 721 605, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1595-9587.160771

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  Abstract 

Background: Intensive Therapeutic Units (ITUs) are unfortunately the epicenters of hospital acquired infection (HAIs). Limited data is available regarding the burden of HAIs in Indian ITU, especially median time of its detection, prevalent organisms and its resistance patterns. We conducted a prospective surveillance aimed to determine the occurrence of device associated infections (DAIs) rate, magnitude of device associated infection cases per 1000 bed days, incidence of infections per 1000 device days and median time for detection of DAIs. Study population was taken from a 25 bedded intensive therapeutic unit (ITU), of a government teaching hospital in India. Methods: A prospective cohort study was performed over two years duration from June 2011 to May 2013. Total 596 patients who were admitted in the ITU for more than 48 hours were followed until discharge. CDC/NNIS system definitions for DAIs were used and rates were calculated. Data were analyzed with descriptive statistics. Results: Cumulative incidence rate of HAIs was 23.15 (138/596) and isolated DAIs was 19.96 (119/596). There was high device utilization mainly for urinary catheter (.838) and IV catheter (.742) than ventilator (.310) but the incidence density was more in ventilator associated infection(VAP-7.38%) than catheter associated urinary tract infection (CAUTI-7.21%) and catheter related blood stream infection (CRBSI-5.37%). Chi-square value for MV(mechanical ventilation) was found 42.59 (<0.001) and ODD Ratio (OR) was 6.8 at CI 3.44-13.67. For urinary catheter(UC) and IVCatheter Chi-square value was 1.13 and 1.94. OR was 1.67 (0.61-4.93) and 4.71 (0.67-94.03). Median time of acquiring VAP, UTI, BSI were maximum in between (9 to 11 days), (17 to 20 days) and (12 to 14) days respectively; indicates requirement of regular follow up of devices within thisZ periods. Major pathogens for VAP Klebsiella (28%), Acinetobacter(26.3%) and Pseudomonus (21%). For CAUTI Staphylococcus aureus (18.7%), pseudomonas and Klebsiella (14.6%) each. CRBSI mainly by gram positive Staphylococcus aureus (24.2%) and Coagulase negative Staphylococcus (12.1%), Acinetobacter (18.2%) and Staphylococcus aureus (15.2%). Conclusion: Although the distribution of pathogens was similar to previous reports, a high rate of device associated infection in ITU can be prevented by regular follow-up of devices, early change of invasive devices within its median time of infection or to avoid unnecessarily prolong use.

Keywords: Comorbid illness, device-associated infection, intensive therapeutic unit, median time of infection


How to cite this article:
Jana A, Majumdar A, Jana A, Mitra J, Biswas S, Bag B, Pal N K. Importance of medium time in case of device-associated infection. J Clin Sci 2015;12:51-6

How to cite this URL:
Jana A, Majumdar A, Jana A, Mitra J, Biswas S, Bag B, Pal N K. Importance of medium time in case of device-associated infection. J Clin Sci [serial online] 2015 [cited 2022 Oct 2];12:51-6. Available from: https://www.jcsjournal.org/text.asp?2015/12/1/51/160771


  Introduction Top


Device-associated hospital-acquired infections (DA-HAIs) in the intensive therapeutic unit (ITU) is one of the leading causes of threat to patient safety of patients, particularly for ventilator-associated pneumonia (VAP), catheter-related bloodstream infection (CRBSI), and catheter-associated urinary tract infection (CAUTI). [1] Various factors contribute to this malady, particularly prolonged length of hospital stay, excessive use of invasive devices for prolonged periods [device utilization (DU)], and increased bacterial resistance in the ITU, particularly in the developing world. [2] According to the International Nosocomial Control Consortium (INICC) report, data from 36 developing countries were analyzed and found to be very similar to DU seen in US ITUs [as per the Centers for Disease Control and Prevention (CDC) and the National Healthcare Safety Network's (NHSN's) systematic surveillance data]. [3]This high HAI rate is effectively addressed by focusing on the burden of the vulnerable part of the health-care system. [3]

In India, as in other developing countries with limited resources, accurate knowledge of DU is often underestimated by many health care workers (HCWs). Also, very scanty data on DA-HAI have been reported to date. [4] The rationale behind this article is to advance the knowledge of DA-HAIs in developing countries by assessing the device-associated infections (DAIs) rate, its incidence density, DU ratio, and the median time of acquiring DAIs to detect its presence early by regular follow-ups of the devices in ITUs. Constant surveillance, along with calculation of the rates of DAI per 1,000 device days and 1,000 patient days, and also the median time of infection of each DAIs give an idea about the necessity of changing or following up the devices at appropriate and regular intervals. In India, there are several works on the detection of HAIs in relation to device days but not a single work on the importance of detection of median time in controlling DA-HAIs.


  Materials and Methods Top


Study design

We conducted a prospective cohort study from June 2011 to May 2013 in a 25-bedded ITU at a government teaching hospital in the city of Kolkata, West Bengal, India. We selected all the patients admitted for more than 48 h and those carrying any invasive devices. We tried to collect samples regularly and sent it to the microbiology laboratory using standardized methods, as described in the CDC/NHSN definitions. In this ITU, the nurse-to-patient ratio was 1:2, the physician-to-patient ratio was 1:4, and the ITU cleaner-to-bed ratio was 1:8. This was the first surveillance study performed in this ITU.

Study analysis

Total 596 patients admitted in this ITU were included in this study and followed up until their discharge. Outcome surveillance during the surveillance period were DAIs rate, incidence density of VAP (number of cases per 1,000 mechanical ventilator days), CRBSI [number of cases per 1,000 intravenous (IV) catheter days], CAUTI (number of cases per 1,000 urinary catheter days), DA-HAI (per 1,000 patient days); DU ratio were recorded based on the CDC/NHSN definitions and to calculate the median time of acquiring DAIs, that is, the median few values when the DAIs were commonly detected. [5],[6]

DU ratio calculation

DU ratios were calculated by dividing the total number of device days by the total number of patient days. Device days are the total number of days of exposure to the device Central line, Mechanical ventilation, Urinary catheter (CL, MV, or UC) for all of the patients in the selected population during the specified time period. Patient days are the total number of days that the patients are in the ITU during the specified time period. [7]

Culture techniques

VAP

In all the cases, a deep tracheal aspirate from the endotracheal tube was aerobically cultured and stained with Gram stain.

Central venous catheter-BSI

The CVCs were aseptically removed and the distal 5 cm of the CVC was amputated and cultured using a standardized semiquantitative method. [8] Concomitant blood cultures were percutaneously drawn in all the cases.

CAUTI

A urine sample was aseptically aspirated from the sampling port of UC and quantitatively cultured. In all the cases, standard laboratory methods were used to identify the microorganisms and a standardized susceptibility test was performed.

Definitions: VAP

VAP is indicated in a mechanically ventilated patient with a chest radiograph that shows new or progressive infiltrates, consolidation, cavitation, or pleural effusion. In patients without underlying cardiac or pulmonary disease, one definitive chest x-ray or computed tomography (CT) scan is sufficient with at least one of the following symptoms: Fever (temperature >38°C) with no other cause, leukopenia [<4,000 white blood cells (WBCs)/mm 3 ], or leukocytosis (12,000 WBCs/mm 3 ). The patient must also have at least one of the following criteria: New onset of purulent sputum or change in the character of sputum; cough, dyspnea, tachypnea, and organism cultured from blood; or isolation of an etiologic agent from a specimen obtained by tracheal aspirate, pleural fluid, bronchial brushing, or bronchoalveolar lavage. [9]

CVC-associated BSI

CVC-associated BSI is a laboratory-confirmed BSI where a patient with a CVC has a recognized pathogen that is isolated from one or more percutaneous blood cultures after 48 h of vascular catheterization and is not related to an infection at another site. The patient also had at least one of the following signs or symptoms: Fever (temperature >38°C), chills, or hypotension. Skin commensals (for example, diphtheroids, Bacillus spp., coagulase-negative staphylococci (CoNS), or micrococci) are organisms cultured from two or more blood cultures. As these mentioned organisms are very commonly present as skin commensals, we have collected a second sample for the confirmation of our results to exclude any sampling error. [9]

CAUTI

For the diagnosis of CAUTI, the patient must meet one of the two criteria. The first criterion is when a patient with a urinary catheter has one or more of the following symptoms with no other recognized cause: Fever (temperature >38°C), urgency, or suprapubic tenderness when the urine culture is positive for 10 5 colony-forming units/mL or more, with no more than two microorganisms isolated. The second criterion is when a patient with a urinary catheter has at least two of the following conditions with no other recognized cause: positive dipstick analysis for leukocyte esterase or nitrate, pyuria (≥10 leukocytes/mL of urine), organisms seen on Gram stain, clinical diagnosis of urinary tract infection, or where a physician initiates appropriate therapy for a urinary tract infection. [9]

Statistical analysis

Epi Info ® version 6.04b (CDC, Atlanta, GA, USA) was used for data analysis. DU rates were calculated by dividing the total number of device days by the total number of patient days. Rates of VAP, CVC-BSI, and CAUTI per 1,000 device days were calculated by dividing the total number of HAI by the total number of specific device days and then multiplying the result by 1,000.


  Results Top


Study population and survey rate

The total study population over the last 2 years who had an ITU stay of more than 48 h was 596; among them, 37 expired during the study period. A total of 37 patients who expired during this period were also included. The median ITU stay was 12 days.

Characteristics of study subjects

In this study, sex is not much correlated to the occurrence of DAIs but with an increase in age, the incidence increases. In our study population, most were in the age group of 40-60 years (37.4%); however, HAIs were present most in the age group of ˃60 years (32.7%) compared to the age group of 40-60 years (20.6%), and it was much less in the age group of 20-40 years (18.9%). Many DAIs were also associated with different comorbid illnesses, namely, malignancy (47%), chronic renal disease (CRD) (42.8%), diabetes (35.2%), chronic obstructive pulmonary disease (COPD) (30.5%), chronic liver failure (27%), and cerebrovascular accident (CVA) (15.6%) [Table 1].
Table 1: Surveillance data and clinical characteristics


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Incidence of nosocomial infection

This study diagnosed NIs-nosocomial infections NIs based on the clinical- and culture-proven evidences, according to the CDC definition of NIs. Of our ITU patients with ITU stay > 48 h, 23.15% (138/596) acquired infection during their ITU stay and more than 90% of them were associated with any of the invasive devices, and the DAIs rate was 19.96% (119/596). In this study, the DU ratio of VAP was the lowest at 0.310, whereas for CAUTI and CRBSI it were 0.838 and 0.742, respectively, while DAIs rate (incidence density) per 1,000 device days for VAP, CAUTI, and CRBSI were 13.89, 3.81, and 3.77, respectively, [Table 2]. Chi-square value for MV was found to be 42.59 (<0.001) and odds ratio (OR) was 6.8 at confidence interval (CI) 3.44-13.67. For UC and IV catheter, Chi-square values were 1.13 and 1.94, respectively, while OR values were 1.67 (0.61-4.93) and 4.71 (0.67-94.03), respectively, [Table 3].
Table 2: Incidence densities of DAIs rate, DU ratio, DAI per 1,000 patient days or 1,000 device days


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Table 3: Chi-square value and OR of different types of DAIs


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Median time from admission to development of nosocomial infection

In this study, the median time of acquiring VAP, UTI, and BSI were maximum in between 9 days to 14 days, 16 days to 21 days, and 12 days to 17 days, respectively, whereas the median time of acquiring the same infection in the absence of DU were 24-29 days for pneumonia, 41 st day for UTI, and 39 th day for BSI [Table 4], [Figure 1].
Figure 1: DAIs and median days of infections

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Table 4: The time of infection from ITU admission


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Distribution of pathogens by major infection sites

In the present study, the most commonly found organisms in ITU were Klebsiella spp. (19.56%), Acinetobacter spp. (18.1%), Pseudomonas spp. (16%),  Escherichia More Details coli (E. coli) (12.3%), and Staphylococcus aureus (14.5%). Most frequently occurred DAI was VAP (7.38%) and the most prevalent organisms in this group were the gram-negative organisms like Klebsiella spp. (28%), Acinetobacter spp. (26.3%), Pseudomonas spp. (21%), and S. aureus (10.2%). CAUTI was the second most common HAI and the main causative organisms were also gram-negative bacteria of the Enterobacteriaceae group of which E. coli (15.2%), Klebsiella spp. (12.1%), Pseudomonus spp. (14.6%), S. aureus (12%), and Candida spp. (10.4%) are commonly found. Among CRBSI, gram-negative and gram-positive organisms were equally found. Among the gram-positive organisms, S. aureus (24.2%), CoNS (9.1%), and among the gram-negative organisms, Acinetobacter spp. (18.2%), E. coli (15.3%), and Klebsiella spp. (12%) are commonly found [Table 5] and [Table 6].
Table 5: Culture-proven bacteremic findings in HAI groups


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Table 6: Resistant pattern of ESBL and AmpC and non-β-lactamase strains


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  Discussion Top


Utilization of invasive devices is increasing in ITU settings to provide long-term access, but infection remains a major problem. Early diagnosis and treatment are vital to reduce morbidity and mortality. During the study period, we tried to register all HAIs even more systematically and evaluate the magnitude of DAIs per 100 hospital admissions, the magnitude of DAI cases per 1,000 bed days, the incidence of infections per 1,000 device days, and the median time for detection of DAIs.

Most of the admitted patients had different comorbid illnesses. DAIs were recorded in 47% patients having malignancy, 42.8% patients having CRD, 35.2% of diabetic patients, 30.5% of patients having COPD, and 27% of patients with chronic hepatic disease (CHD), which is much higher than incidence rate of total HAI. It was also evident that more than 50% of patients having comorbid illness were prone to develop HAIs.

A similar type of previous study showed that infections per 1,000 patient days ranged from 20% to 43.8%, [10],[11],[12] but in the present study it was 7.45/1,000 patient days; this indicates that better health-care services prevent prolonged length of hospital stay. Incidence rate for VAP (7.38%) was lower than that found in the other study (9.6-19%) but incidence rates for CAUTI (7.21%) and CRBSI (5.37%) were almost similar to the findings of the studies done in other developing countries (CAUTI: 3-9.7% and CRBSI: 6.3-8%). [10],[12],[13]

Occurrence of DAIs was analyzed using Yates' Chi-squared test. The results are reported in [Table 3] and it was found that invasive devices are significant risk factors for HAIs. OR also confirmed the results.

The incidence density in another similar study done in the intensive care unit (ICU) was 9.4-25 device days for VAP, 3.8-12.5 device days for UTI, and 8.5-9 device days for BSI. [10],[11],[12] In the present study, the incidence density is 16.2 device days, 4.96 device days, and 4.47/1,000 device days, respectively, which is similar to that in other developing countries but the value is much higher than in the developed countries. It also indicates prolonged use of devices and the lack of their follow-ups in the developing world.

In this study, the DU ratio of VAP was the lowest at 0.310, whereas for CAUTI and CRBSI, it was 0.838 and 0.742, respectively, while the DAIs rate (incidence density) per 1,000 device days for VAP, CAUTI, and CRBSI were 16.2, 4.96, and 4.47, respectively. Though the utilization of a ventilator is lower than that of other devices, the incidence of this infection is much high; so, we can conclude that the use of a ventilator is the most significant risk factor and it infects earlier than other devices.

In this study, the median time of acquiring VAP, CAUTI, and CRBSI were 9-14 days, 16-21 days, and 12-17 days, respectively, whereas the median time of acquiring the same infection without devices were 24-29 days, 41 days, and 39 days for pneumonia, UTI, and BSI, respectively. Therefore, it is better to change these devices within the median time of infection or the sample should be sent for microbiological test within this time, in the case of both symptomatic and asymptomatic patients.

The pattern of organisms in the present study were Klebsiella spp. (19.56%), Pseudomonas spp. (15.94%), Acinetobacter spp. (18.1%), and S. aureus (14.2%), followed by E. coli (10.6%) showing nearly similar results like other studies except the percentages of Klebsiella spp. among the gram-negative organisms and S. aureus, including methicillin-resistant S. aureus (MRSA) among the gram-positive organisms are much higher in this study. The pattern of presenting organisms in different DAIs were nearly similar to the other study except, the presence of Enterobacteriaceae group of organisms are high, especially Klebsiella spp. is higher in the present study. [10],[11],[12],[13]

As prolonged stay in the hospital increases in the risk of acquiring infections, we suggest hand hygiene on the part of all HCWs, correct aseptic techniques to use the devices, and the making of a clear aseptic ward surrounding the patients who are staying by the frequent use of proper disinfectants, that should be maintained in the authors' center to reduce DAIs.


  Conclusion Top


ITU-acquired infections are the independent risk factors for hospital mortality and morbidity, and increased hospital stay and cost. DU in critically ill patients is responsible for a high risk of complications such as VAP, CAUTI, and CRBSI. One of the main strategies to prevent DAIs in the ITU is strict control of hand disinfection and early change of invasive devices, or to avoid their unnecessary prolonged use. DAIs can be reduced by regular follow-ups based on its median time of infection in individual study institutes, because the median time of infection varies in different centers depending on their health hygiene policies. A strict hand hygiene policy, staff education, and the implementation of maximal barrier precautions, especially the use of hand disinfection on catheter insertion and the proper handling of catheters and their regular follow-ups might reduce the number of DAIs.

Limitation of the study

Over 1-year prospective collection of data from a single ITU is not a model representative of the whole hospital nor is it sufficient to reflect the situation of the whole country, but can focus on the practical situation. In contrast to a single center study, the study populations in multicenter studies are often heterogeneous. Different admission policies, different levels of expertise of the members, resources, and treatment procedures vary among the centers, which may equivocate the actual situation.

 
  References Top

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van der Kooi TI, de Boer AS, Manniën J, Wille JC, Beaumont MT, Mooi BW, et al. Incidence and risk factors of device-associated infections and associated mortality at the intensive care in the Dutch surveillance system. Intensive Care Med 2007;33:271-8.  Back to cited text no. 10
    
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Legras A, Malvy D, Quinioux AI, Villers D, Bouachour G, Robert R, et al. Nosocomial infections: Prospective survey of incidence in five French intensive care units. Intensive Care Med 1998;24:1040-6.  Back to cited text no. 12
    
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Fernández-Crehuet R, Díaz-Molina C, de Irala J, Martínez-Concha D, Salcedo-Leal I, Masa-Calles J. Nosocomial infection in an intensive-care unit: Identification of risk factors. Infect Control Hosp Epidemiol 1997;18:825-30.  Back to cited text no. 13
    


    Figures

  [Figure 1]
 
 
    Tables

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


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