Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 28, Num. 4, 2010, pp. 342-347

Indian Journal of Medical Microbiology, Vol. 28, No. 4, October-December, 2010, pp. 342-347

Original Article

Surveillance of device-associated infections at a teaching hospital in rural Gujarat - India

S Singh, Y Pandya, R Patel, M Paliwal, A Wilson, S Trivedi

Department of Microbiology, PS Medical College Karamsad & Shree Krishna Hospital, Karamsad - 388 325, Gujarat, India
Correspondence Address: S Singh, Department of Microbiology, PS Medical College Karamsad & Shree Krishna Hospital, Karamsad - 388 325, Gujarat, India, sumansingh505@hotmail.com

Date of Submission: 23-Mar-2009
Date of Acceptance: 01-Jul-2010

Code Number: mb10102

PMID: 20966566
DOI: 10.4103/0255-0857.71830

Abstract

Purpose: Surveillance of hospital-acquired infection (HAI), particularly device-associated infection (DAI), helps in determining the infection rates, risk factors, and in planning the preventive strategies to ensure a quality healthcare in any hospital. The present study was carried out to know the prevalence of DAI in a tertiary care teaching hospital of rural Gujarat.

Materials and Methods: A prospective, site-specific surveillance of three common DAIs that is catheter-associated urinary tract infection (CA-UTI), IV-catheter-related bloodstream infection (IV-CRBSI), and ventilator-associated pneumonia (VAP) was carried out between July 2007 and April 2008, in different wards/ICUs. A surveillance plan, with guidelines and responsibilities of nurses, clinicians and microbiologist was prepared. Infection surveillance form for each patient suspected to have DAI was filled. The most representative clinical sample, depending on the type of suspected DAI, was collected using standard aseptic techniques and processed for aerobes and facultative anaerobes. All the isolates were identified and antimicrobial sensitivity testing performed as per CLSI guidelines. An accurate record of total device days for each of the indwelling devices under surveillance was also maintained. Data, collected in the prescribed formats, were analysed on monthly basis; and then, compiled at the end of the study. Descriptive analysis of the data was done and DAI rate was expressed as number of DAI per 1000 device days.

Results: The overall infection rate for CA-UTI, IV-CRBSI, and VAP were found to be 0.6, 0.48, and 21.92 per 1000 device days, respectively. The organisms isolated were Staphylococcus aureus, CONS, Enterococci, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli.

Conclusions: Duration of indwelling devices was found to be the major risk-factor for acquiring DAIs. Low DAI rate might have been due to use of antibiotics, often prophylactic. Active surveillance is quite a tedious and time-consuming process; however the outcome is useful in prevention and control of DAIs.

Keywords: Device-associated infections, targeted surveillance, ventilator associatedpneumonia

Introduction

Surveillance can be scientifically defined as a systematic, active on-going observation of the occurrence and distribution of a disease within a population and of the events that increase or decrease the risk of the disease occurrence. ^[1] Hospital-acquired infections have proven to be the most common cause of increased morbidity, mortality, and the cost of the hospitalized patients more so in the intensive care units (ICUs) ^.[1],[2],[3]

Keeping in mind the importance of HAI, persistent effort is required to minimize the risk of developing such infections in every good health care institute. Hospital-Acquired Infection Control Committee (HAICC) at Shree Krishna Hospital (SKH) with its active infection control team is responsible for ensuring the implementation and monitoring of infection control practices. Adherence to the hand hygiene norms is a routine. Surprise environment sampling from different hospital locations helps in creating a sense of alertness in following the infection control procedures such as cleaning, disinfection, and sterilization at different locations including wards, ICUs, and operation theatres. Indwelling devices are also checked for the type of care taken to prevent the development of infection. Outcome of the efforts to minimize the risk of infection can be monitored by surveillance studies.

Surveillance of HAI; particularly DAI, also helps in determining the infection rates, risk factors, and in further planning the preventive strategies to ensure a quality health care in any hospital. ^[1],[2],[3]

Data on surveillance of HAI in relation to device is available from National Nosocomial Infection Surveillance (NNIS) System report, which is an international data and usually pooled from different hospitals. ^{[4],[5],[6],[7],[8],[9]} Such data cannot be generalized, as each hospital has its own factors that can influence the rates of HAI. Data involving surveillance of DAI are not available from single institutions. Ours is a tertiary care teaching hospital located in the rural setting of Gujarat, India, with an active infection control committee. It was therefore decided, as a part of HAI control policy, to undertake surveillance studies for various DAIs in wards and ICUs in Shree Krishna Hospital in the year 2007 and 2008, with the main objectives to know the prevalence of DAI along with the risk factors, pathogens, and any other associated factors.

Materials and Methods

A prospective, site-specific surveillance of DAI was carried out from July 2007 to April 2008 in different wards and ICUs, on a rotating basis at SKH. The present study was reviewed and duly approved by the Institutional Human Research Ethics Committee.

The study was targeted at three common DAIs: catheter-associated urinary tract infection (CA-UTI), IV catheter-related bloodstream infection (IV-CRBSI), and ventilator-associated pneumonia (VAP) as defined by the CDC's National Nosocomial Infections Surveillance (NNIS) system criteria. ^[1],[3],[4]

A surveillance plan, with guidelines and responsibilities of nurses, clinicians and microbiologist, was prepared. Each of them was well informed about the plan and trained for sample collection.

A trained Infection Control Nurse (ICN) visited the various locations of the hospital on daily basis to collect patients' demographic details (name, age, sex), date of hospital admission, type of clinical illness, type of devices inserted along with the time and date of device insertion for the new admissions. For already enrolled patients, the device days were recorded till the device was removed, along with the observation of doctors and nursing notes to look for any signs of infection. Clinicians on duty were also consulted if required. If infection was suspected, the most appropriate clinical sample for the type of device was collected and sent to microbiology laboratory without delay. Infection surveillance form with necessary details was filled up simultaneously by the consultant.

Laboratory methods used to diagnose CA-UTI, IV-CRBSI, and VAP along with the interpretation were as follows:

Catheter-associated urinary tract infection

A patient was said to be suffering from catheter-associated urinary tract infection (CA-UTI) if he was catheterized and he developed one or more of the following condition that is fever (temp ≥ 38°C) without any other known cause, urgency or suprapubic tenderness with urine culture showing more than 10 ⁵ colony-forming units or more per ml of urine, with not more than two types of organism.

CA-UTI was also considered when urine showed pyuria (more than 10 leukocytes per ml of urine) or more then three WBC were seen per high-power field in centrifuged urine and organism seen on Gram stain or clinician strongly suspecting UTI to start antibiotics.

Ventilator-associated pneumonia

A patient was said to be suffering from ventilator-associated pneumonia (VAP) if he was on mechanical ventilator and developed a new fever and cough with development of purulent sputum, in combination with radiological evidence of a new or progressive pulmonary infiltrate, leukocytosis, a suggestive Gram's stain, and growth of bacteria in cultures of sputum, tracheal aspirate, pleural fluid or blood.

Intravascular catheter-related bloodstream infections

If a patient had a recognized pathogen cultured from one or more blood cultures and if organisms cultured from blood were not related to an infection at another site, it was labelled as a case of intravascular catheter-related bloodstream infections (IV-CRBSI).

The most representative samples were collected and processed by standard aseptic techniques for aerobes and facultative anaerobes. In case of CA-UTI, urine was collected from the urinary catheter sampling port with a sterile needle and syringe. Deep tracheal aspirates or if available bronchial washing were collected for VAP. In case of IV-CRBSI, IV was removed aseptically; the distal 5 cm of the IV catheter was cut and sent to microbiology laboratory along with the blood culture collected from the other arm.

Quantitative and semi-quantitative culture was used for urine and respiratory samples. For urine, a count of more than 10 ⁵ colony-forming units per ml or more, and with no more than two micro-organisms isolated was considered as a confirmation of UTI. For respiratory samples, a count of more than 10 ³ (for BAL) and 10 ⁵ (for tracheal aspirates) was considered as diagnostic of VAP. ^[10] All the isolates were identified by standard microbiologic techniques. Antimicrobial sensitivity testing was done by Kirby-Bauer disc-diffusion test. The isolates were tested for methicillin-resistance and ESBL production as per CLSI guidelines.

For data collection and descriptive analysis, two important parameters were considered. They were:

Denominator data (population at risk)

This included all patients exposed to the particular device during surveillance period. A total number of device days was thus calculated.

Numerator data

This included number of patients who developed bacteriologically confirmed infection on a particular device as per the standard definitions.

Device-associated infection rate was expressed as the number of DAI per 1000 device days, as calculated by dividing the number of persons developing device-associated infection by the total number of device days and multiplied by 1000.

Data, collected in the prescribed formats, were analysed on monthly basis to implement any early interventions and then compiled at the end.

Results

During the study period of 10 months, a total of 15, 927 patients were hospitalized in different wards and ICUs, for an aggregated duration of 59, 018 days in different wards and ICUs. Out of these, 2380 patients were exposed to various devices for a total duration of 8110 device days with a utilization rate of 6.69%. The overall DAI rate combined for different wards and ICUs was found to be 0.38% or 1.1 DAI per 1000 device days.

There was only one case of CA-UTI with 4-7 days of catheterization observed in the Medical Intensive Care Unit (MICU), caused by Enterococci spp. during the study period, giving an infection rate of 0.6 per 1000 device days [Table - 1]. The prevalence of CRBSI was found to be 0.48 per 1000 device days; as three cases of DAI were detected with a total of 6217 device days; two of them developed infection after seven days of catheterization. Two strains of CONS and one of Klebsiella spp. were isolated from these three cases [Table - 2]. As shown in [Table - 3], five cases of VAP were confirmed with a total of 228 device days during the study period, four of them developed infection after four days on ventilator, giving an infection rate of VAP 21.92 per 1000 device days. From these five cases, two strains of K. pneumoniae and one each of Pseudomonas aeruginosa, S. aureus, and E. coli were isolated.

Ventilator-associated pneumonia (5.74% or 21.92 per 1000 device days) was the commonest DAI followed by CA-UTI (0.23% or 0.6 per 1000 device days) and IV-CRBSI (0.16% or 0.48 per 1000 device days) in hospital. All the DAI were observed in ICUs and the infection rate when calculated only for ICUs was 1.38% or 2.6 per 1000 device days. It was 21.92, 1.16, and 1.28 per 1000 device days for VAP, CA-UTI, and IV-CRBSI, respectively, in ICU patients.

The organisms isolated were predominantly Gram negative that is K. pneumoniae (4), E. coli (1), and Pseudomonas aeruginosa (1), followed by Gram positive organisms such as CONS (2), S. aureus (1), and Enterococcus faecalis (1). The isolates were found to be highly drug-resistant. All E. coli and half of the K. pneumoniae isolates were ESBL positive; while S. aureus isolate was methicillin-resistant. Pseudomonas aeruginosa strain was found sensitive only to imipenem, thus demonstrating the "difficult to treat" nature of nosocomial pathogens.

Discussion

Health care associated infections, particularly those acquired following insertion of devices, are serious cause of concern for hospitals. ^{[1],[2],[3],[4],[5],[6],[7],[8],[9]} Regular surveillance of device-associated infections in any healthcare setting is therefore highly informative not only to clinicians but also to administration in deciding strategies for the prevention and control of such infections. However, in view of the difficulties in conducting such studies prospectively, there has been only sparse information available on Institutional DAI rate in the literature particularly from India.

The overall HAI rate associated with indwelling devices in the present study was found to be 0.38%, which is quite low in comparison to that reported in various studies ranging from 4.9 to 8.5%; and, besides an active role of HAICC in the prevention of HAI, it might be due to frequent use of antimicrobials. ^{[11],[12],[13]}

In the present study, a prospective surveillance was carried out for three main DAI, namely, VAP, CA-UTI, and CRBSI in different wards as well as ICU. We did not find any infection in wards associated with urinary catheter as well as IV catheters during the study period as compared to 6.8 CA-UTI per 1000 device days by Vonberg et al. ^[14] There has been a significant difference in the infection rates in ICUs and non-ICU settings. DAI infection rate in non-ICU setting are different due to difference in the device days, length of hospital stay, and disease severity in patients.^[14] Intensive care setting is however a high-risk area for acquiring DAI as evident by the high rates of infection in these areas. ^[9],[13] In a single day point prevalence study of HAI in Saudi Arabia, 46.7% of DAI have been reported from ICUs. ^[16]

In the present study, a total of 649 cases in ICUs with 3421 days of exposure to devices were studied for DAI. The overall infection rate was found to be 1.4% or 2.6 per 1000 device days, all found in ICU setting only; which is very low in comparison to the infection rates in other studies. ^[13] Findings of the International Nosocomial Infection Control Consortium (INICC) for DAI in ICUs of seven Indian cities has found overall infection rate of 4.4%. ^[13] In a similar study involving ICUs of ten Columbian hospitals, DAI was found to be 12.2% or 18.2 per 1000 patient's days, whereas in Argentina, infection rate was found to be as high as 30.3 per 1000 device days. ^[4],[16]

VAP is an important DAI as a result of mechanical ventilation in the available studies. ^{[4],[13],[15],[17],[19]} We studied 87 patients kept on ventilators, for 228 device days in different ICUs, for VAP. Out of them, eight were suspected for VAP, five patients were confirmed microbiologically ensuing an infection rate of 5.7% or 21.92 per 1000 device days; which was remarkably high when compared to US infection rate of 5.1 per 1000 device days, but comparable to that of a Turkish study, reporting a rate of 20.8% or 24.1 infections per 1000 device days. ^[17],[18] Rates of VAP have ranged from 10.5 to 34.8% in different studies. ^{[4],[13],[15],[17],[19]} Longer duration on device increases the risk of DAI as was also seen in the present study; four out of five cases of DAI were on ventilator for 4-7 days. Pseudomonas species was the most commonly associated organism (35.8%) with VAP.

In order to determine the rate of CA-UTI, a total of 1665 catheter days, in 428 cases of urinary catheterization in various wards and ICUs were studied in the present study. Nineteen patients were suspected for having CA-UTI, but only one was confirmed bacteriologically; Enterococci spp. was isolated from the same. The overall rate of CA-UTI was 0.23% or 0.60 per 1000 device days; which is very low compared to that of US rates of 3.3 per 1000 device days. The rate of CA-UTI in various studies have ranged from 4.4 to 56.5% or 1.7 to 30 infections per 1000 device days.^{[4],[13],[16],[17],[18]}

For blood stream infection surveillance associated with indwelling devices in the present study, a total of 1865 patients were studied for IV-CRBSI for 6217 device days. IV-CRBSI was confirmed in three cases out of total 33 suspected cases, resulting in an infection rate of 0.16% or 0.48 per 1000 device days. This is quite low in comparison to US and Turkish rates of 3.2 and 9.69 infections per 1000 device days. ^[6] All the patients with confirmed CRBSI were from surgical-ICU with two patients on IV-catheters for more than seven days. Overall peripheral line CRBSI rates have varied from 0.3 to 31.1%. ^{[8],[19],[20]}

The organisms commonly found in HAI are nosocomial pathogens prevalent in the hospital environment. The organisms isolated in the present study were highly drug-resistant K. pneumoniae, E. coli. Pseudomonas aeruginosa, CONS, Staphylococcus aureus and Enterococci; similar to findings in other studies.^[9],[13]

The DAI rates as evident in literature are highly variable, depending upon a number of factors such as type of patients admitted, prescribing habits of the clinicians, antibiotic policy and infection control programs of the institute. Surveillance of health care associated infections is important to understand the nature and extent of problem. This study helped us to produce aggregated DAI rates suitable for inter-hospital comparison and provide information to clinical staff and administration so as to implement effective prevention strategies.

Institutional surveillance data cannot be generalized, while generalized data from multicentric studies cannot be used by the institutions, thus it becomes important to undertake such studies at institutional level. In our institution, increased number of days for indwelling devices was found to be the major risk-factor for acquiring DAIs. Antibiotics, often prophylactic, prescribed to the patients with indwelling devices, might have contributed to overall low-prevalence rates of DAI observed; its use was however to be monitored under a suitable antibiotic policy as felt by others too. Thus, it is concluded that the process of active surveillance of DAIs is quite tedious and time-consuming; however, the outcome is extremely useful in deciding the direction of efforts made by HAICC in prevention and control of DAIs. If guidelines proposed by CDC on prevention of HAI in general and care of indwelling device is followed strictly, rate of DAI can be easily prevented to highest level in a health care institute.

References

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