Epidemiology

Questions:

1) Utilizes epidemiological methods.
a. Describe the epidemiology of the virus or bacteria.
b. Provide the case definition of the virus or bacteria and the rates.
c. Discuss the reservoirs, vectors, transmission, and life cycle of the virus or bacteria.
d. List pathophysiology (etiology, manifestations, treatment, and prognosis).
e. Discuss risk factors.
f. Confirm diagnosis of initial case by clinical and laboratory findings.

2)Uses statistical methods (Use attached CLABSI data sheet to write the rates. The date of the data is Sept 2015 quarter three).
a.Calculate and present rates.
b.Summarize results.

3)Reports to appropriate staff/agencies.
a.Discuss the essential personnel to be notified and who should be on the team to investigate and plan control interventions including external agencies.
b.Discuss how additional cases will be identified and added to data collection form.

4)Recommends prevention and control strategies.

Answers:

Introduction

Central Line Associated Bloodstream Infection (CLABSI) mainly occurs by multiplication of germs on intravascular catheters placed to collect blood samples and provide fluids and medicines.  Formation of biofilms on the surface of the catheter increases the risk of contamination and CLABSI. Microorganisms migrate from catheter to blood stream. There are 80000 CLABSI estimated to occur every year in U.S. The lack of prevention measures during insertion of the device is a major drawback. According to NHSN, there is an increase the incidence of CLABSI each year in U.S. hospitals. However, there is the significant reduction in CLABSI rate in acute care hospitals in U.S between 2013- 2014. The chosen hospital in this paper is “UCSF Medical Centre”. The rate of occurrence of CLASBI in 2015 at UCSF Medical Centre is 1.1 per thousand central line days. The centre reported in 2009 that the occurrence of CLABSI in ICU of this hospital were 18000 whereas, it was 43,000 in 2001. Therefore, CLABSI can be prevented through evidence-based clinical interventions. The paper lays particular emphasis on UCSF Medical Centre in U.S and outlines how it measures the rate of infection as per the guidelines of NHSN and current CLABSI rate. This paper gives an overview of CLABSI infection along with the epidemiological methods and discusses risk factors. It explains how CLABSI is confirmed by clinical and laboratory findings. The paper contains statistical calculations of present rates and the summary of results. Further, it provides brief details on the clinical intervention of CLABSI and preventive measures taken by UCSF centre against CLABSI. The paper suggests recommendations for medical professionals on how to control the disease by external agencies and ends with the summary of the findings.

1. Utilizes epidemiological methods

a) Bacterial and viral epidemiology deals with inhibition of infectious chain in population during the disease outbreak. It includes identifying the source of an outbreak and developing controlled measures to disrupt the process of transmission (Marschall et al., 2014).

B) CLABSI or laboratory-confirmed bloodstream infection occurs within 48 hours of the placement of the catheter at a site and is not related to infection in any other part of a body. The causative organisms of CLABSI infection include S. aureus, E.coli, Candida sp and Enterococcus sp. The case definition of CLABSI must meet three criteria:-

• If the blood cultures of a patient and that of culture tip show any of the above-recognised pathogens and is same in both the cultures, then it can be confirmed as BSI provided the organism must not be related to any other infection in the body.
• Patients should show the symptoms of fever, chills or hypotension, and symptoms must not be due to any other infection in the body. Two or more blood culture is drawn separately and “common skin contaminant” is cultured from the above cultures.
• Person of or under one year age must have symptoms like fever (>38°C), hypothermia, apnoea and abnormal slow heart rate.
• All the symptoms and positive diagnostic results should exclusively be developed due to CLASBI. Two or more blood culture is drawn separately and “common skin contaminant” is cultured from the above cultures (Beekmann et al., 2012).

CLABSI rate is calculated as follow:-

Number of CLABSI x 1000/ Number of central line days (Edwards et al., 2008 )

c) Reservoirs- include host or habitat for a microorganism to multiply which can be humans, animal or environment. People who are infected and ill due to organisms are categorised into acute clinical cases. A patient who harbours the infectious agent but do not develop the diseased condition is known as carriers. The later possess the threat to transmit the disease to other people. Animal reservoirs are described same way as that of the human. Environmental reservoirs include plants, soil, water, the surface of medical equipment like the catheter, etc. Reservoirs are also called as vectors (Coffin & Zaoutis, 2005).

Vector is a medium, which can be an organism that transfers microorganisms from one host to another but itself is not responsible for the disease. Vectors are also used in recombinant DNA technology for delivering vaccines. (Paitoonpong et al., 2013).

Transmission denotes mode by which pathogens transmit or forms the symbiotic relationship with one of the reservoirs to pass the communicable diseases. Vertical transmission occurs from parents to offspring. Horizontal transmission occurs through environment and unrelated individuals example nitrogen fixation by Rhizobium (Bauman, 2013).

The life cycle of bacteria (example E.coli) bacterial cells divides by the process of asexual division named as binary fission. During this process, the cell number increases and the bacteria form new protoplasm. As the cellular DNA replication is completed and the strand of DNA is attached to the plasma membrane the cell elongates. Thus, the newly replicated DNA is then separated. The mother cell splits into two daughter cells by formation of the septum in the middle of the cell, after the invagination of the plasma membrane which is known as cytokinesis. FtsZ protein mediates the process of septal invagination and regulates the cell division (Bauman, 2013).

d) Pathophysiology – the most common method of pathogenesis include migration of the pathogens from skin to external and internal surface of the catheter and to the bloodstream after one week of placing in the body. Contamination of infused substance or contamination due to lack of proper sterile technique or other systemic infection in the body also causes CLABSI (Latif et al., 2015).

Treatment plan includes the prescription of the antibiotics to reduce the infection based on the recognised microorganism in the blood cultures and replacement of the catheter with the new one (Yokoe and Classen, 2008).

e) Risk factors- A patient may face additional risk factors with CLABSI are increase in the severity of disease, compromised skin integrity, a chance of granulocytopenia and occurrence of further infection. Catheter-associated risk factors included a type of the catheter and number of lumens, duration of the catheter in situ and antimicrobial coating. Operative risk factors include inadequate aseptic technique during the placement of the catheter and its frequent access (Wylie et al., 2010).

f) Diagnosis – Infection is detected by collecting the blood sample aseptically from antecubital veins on either side of the catheter and cultured for the presence of recognised microorganisms is reported as CLABSI. However, if the patient develops bloodstream infection due to peripheral IV lines that show presence of the same pathogen as that present in blood and pus, then it is not reported to be CLABSI (Khan & Richardson, 2014).

2) CLABSI data

a) CLABSI rate is calculated by taking the ratio of the count of BSI to the central line days and multiplying the ratio with 1000 (Dudeck et al., 2013).

Incidence rate- It is calculated by dividing the new incidence by the total population at a particular time. For example,

Incidence rate = (5 / 110) x 100 %

        = 4.54%

Prevalence rate- it is the ratio of pre-active cases to the total population during the specific time. In the given example,

Prevalence rate = (5 / 1135) x 100 %

        = 0.44 %

Incidence density rate- It is the measure of a number of diseases occurring over a population at a particular time.

Incidence density = (number of disease onset) / (sum of person – time @ risk)

For example,

13 / (12450-2)

      =    13 / 12448

      =    0.10%

Attack rate (number of new cases observed at a period of time / total population at risk) * 100

For example, if number of new cases observed are 46

Total population at risk is 12450

Therefore, (46 / 12450) * 100%

= 0.36 %

b) According to “Annual improvement performance report 2014-2015”:-it has been noticed that there is a significant reduction in incidence of catheter associated UTI and pneumonia associated to ventilator (“Department of Patient Safety and Quality”, 2016). All the above data is submitted to NHSN. There was the decrease in CLABSI rate by 50% from the year 2008 to 2014. The reason for this decline is the prevention program developed by the USCF. The number of CLABSI decreased from 1.65% in 2009 to 1.11% in 2015.The total number of patients admitted reduced from 42000 in 2001 to 22000 in 2009 in U.S.

3) Reports to appropriate staff/agencies

a) Central line bloodstream infections increase the cost of the hospital lengthening the treatment duration of hospitalization, in cases leading to death. When medical centres as UCSF identifies any case with CLABSI, the infection prevention and control team is informed about it. It should be kept in mind that the doctor of the infection monitoring and prevention team is well notified of every case and situation because he is the person who gives all the necessary guidelines on do’s and don’ts to the team and support them. The team to investigate and plan control would consist of:

• Consultant Nurse Infection Prevention and Control Nurse Joint DIPC (Thom et al., 2014)
• Doctors with experience in infection prevention and control
• Medical microbiologists
• Nurses with specialization in prevention and control of infection
• Support workers for doing audit and surveillance
• Administrator for audit surveillance

People mentioned above as a whole are responsible for advice on CLABSI infection 24*7 hours. They invent new policies and imply them to the relevant departments. They also provide with the valuable specialist advice about the control and prevention of the infection. They participate in the planning and up gradation procedure of the hospital.

The external agencies that plan prevention and control for several infection disease can also be consulted. They are professional and offer their services regarding money. Usually, they plan and imply modifications on existing norms to optimize the activity of the internal CLABSI control team. Centre for Disease control and Prevention (CDC) is one of such organizations, which aim to public safety.

b) There are various data collection techniques that UCSF like organizations can follow as well (Dudeck et al., 2013). Additional data can be identified and added to the data collection form. To understand the trait of the cases, it is often mandatory to include outsourced information on the collection form. This information may be from several sources. As stated by Bloom et al.,(2014) PLOS data policy, organizations like UCSF can access the data from its database, as PLOS is an organization of non-profitability, which aims at the creation of open public library to provide journals and scientific literature containing data and information.

The second source can be interviewing of patients who have had gone through the infection, and they are volunteering to share their personal experience. Each patient or case study can be included in the data form. CLABSI is included in the annual report published by CDC on infectious disease development. UCSF and organizations like that often get data from CDC to include cases in their data form. Morbidity and Mortality Weekly Report (USA) also gives an idea about the cases of CLABSI outside the UCSF, and they get the data from above mentioned sources to include in the data form. Outpatients’ clinics are also an important source of data collection. A task force is there who study the trait, the data collected from the sources mentioned above, and they combine all the relevant data to include them in their collected data –form.

4) Recommends prevention and control strategies

Screening during admission includes detection of MRSA within one day and every 30days during the patient stay. Patients on PiMS alert should undergo full screening of nose and throat. Screening of axilla and other skin lesions should be performed while inpatient. The procedure should comply with NHS guidelines for screening MRSA presence (Bonten & Weinstein, 2015).

Prevention- In order to prevent the increasing CLABSI rate UCSF treats the process of catheter placement as a surgical procedure. Therefore, the medical professionals have to maintain strict aseptic conditions. The patients are covered by sterile drapes. Removal of a catheter is closely monitored and is carried under sterile conditions. A “committee of infection control” regularly visits medical staff to investigate infection rate and review clinical procedures. The committee identifies demerits that caused CLABSI. The following measures showed to reduce CLABSI (Yokoe & Classen, 2008):-

• Handwashing and use of chlorhexidine (2%)
• Use of sterile masks, gloves, sterile gown and caps
• Strict guidelines should be formulated, and incompliance to it from the staff end should be punishable.
• Preference of insertion site should be SCV followed by IJ and then femoral and catheter should have the minimum number of lumens.
• CVL’s used should be coated with antibiotics (like silver sulphadiazine)
• Daily review of CVL should be performed for presence of symptoms (like redness, swelling or pain), dressing integrity, replacement of catheter if risk of suboptimal sterility (Thom et al., 2014)

These prevention strategies also break the cycle of infection and greatly reduce the chance of transmission. The patients must be aware of basic rules to follow during inconvenience. They should be able to communicate effectively with the health care team. They should not know the use of chlorhexidine. They should be taught how to follow aseptic conditions while coming in touch with the central line.

Antibiotics used during CLABSI include vancomycin along with aminoglycosides such as gentamycin mostly used against gram-negative bacteria. Ceftazidime is used against multi drug resistance bacteria (Wylie et al., 2010). Hospitals must strictly implement “antibiotic review policy” and appropriate therapeutic revisions within 48 hours for any clinical indications. Hospitals have developed standardised metric to determine and evaluate antimicrobial use. Several healthcare facilities use NHSN surveillance system and adhere to guidelines to track “antimicrobial use and resistance” Hospitals maintain data entry on antimicrobial use and reports NHSN through “electronic medication and admission record” or “Bar Code Medication administration system” and “Laboratory information system” on antimicrobial resistance (Coffin et al., 2005).

Summary

As per above discussions it can be concluded that CLABSI is a severe disease that may even lead to death if preventive strategies are not followed appropriately. It can be concluded that CLABSI is not a complex medical disease to be handled. The decrease in CLABSI incidence is evident of change in perception and thinking that the harm caused by health care is inevitable. The paper has discussed the epidemiology, pathophysiology and diagnosis of the disease. The paper has detailed the preventive measures for CLABSI. The statistical data of UCSF centre shows that CLABSI has reduced significantly over last few years, and further risk of infection can be avoided by adhering to NSHN guidelines for the surgical procedure. Patients should be screened properly during admission and while inpatient. Patients and staff should be well aware of the formulated guidelines and safety measure for handling central line. The story of success was first heard from John Hopkins Research group that worked with evidence-based strategies to Prevent CLABSI. After implementing clinical interventions, the CLABSI rate has declined by 60% over the period of 36 months. The facility of risk adjusted bench marking is major step in ‘antimicrobial stewardship efforts’

References:

Bauman, R. W. (2013). Microbiology with diseases by taxonomy. Pearson Higher Ed.

Beekmann, S. E., Diekema, D. J., Huskins, W. C., Herwaldt, L., Boyce, J. M., Sherertz, R. J., & Polgreen, P. M. (2012). Diagnosing and reporting of central line–associated bloodstream infections. Infection Control & Hospital Epidemiology, 33(09), 875-882.

Bloom, T., Ganley, E., & Winker, M. (2014). Data access for the open access literature: PLOS’s data policy. PLoS Med, 11(2), e1001607.

Bonten, M. J., & Weinstein, R. A. (2015). Making sense of universal screening for MRSA. The Lancet Infectious Diseases.

Coffin, S. E., & Zaoutis, T. E. (2005). Infection control, hospital epidemiology, and patient safety. Infectious disease clinics of North America, 19(3), 647-665.

Department of Patient Safety & Quality. (2016). Retrieved 23 March 2016, from https://www.ucsfhealth.org/pdf/performance_improvement_report_2015.pdf

Dudeck, M. A., Weiner, L. M., Allen-Bridson, K., Malpiedi, P. J., Peterson, K. D., Pollock, D. A., … & Edwards, J. R. (2013). National Healthcare Safety Network (NHSN) report, data summary for 2012, Device-associated module.American journal of infection control, 41(12), 1148.

Edwards, J. R., Peterson, K. D., Andrus, M. L., Dudeck, M. A., Pollock, D. A., & Horan, T. C. (2008). National Healthcare Safety Network (NHSN) report, data summary for 2006 through 2007, issued November 2008.American journal of infection control, 36(9), 609-626.

Khan, S., & Richardson, S. E. (2014, December). 858Evaluation of Current Methods for the Diagnosis of Catheter-Related Blood Stream Infections (CRBSI) at the Hospital for Sick Children. In Open Forum Infectious Diseases (Vol. 1, No. suppl 1, pp. S246-S247). Oxford University Press.

Latif, A., Halim, M. S., & Pronovost, P. J. (2015). Eliminating Infections in the ICU: CLABSI. Current infectious disease reports, 17(7), 1-9.

Malpiedi, P. J., Pollock, D. A., & Weiner, L. M. (2015). National Healthcare Safety Network report, data summary for 2013, device-associated module.American journal of infection control, 43, 206-21.

Marschall, J., Mermel, L. A., Fakih, M., Hadaway, L., Kallen, A., O’Grady, N. P., … & Yokoe, D. S. (2014). Strategies to prevent central line-associated bloodstream infections in acute care hospitals: 2014 update. Infection Control & Hospital Epidemiology, 35(S2), S89-S107.

Paitoonpong, L., Wong, C. K. B., & Perl, T. M. (2013). Healthcare-associated infections. In Infectious disease epidemiology theory and practice (pp. 369-466). Jones&Bartlet Learning.

Thom, K. A., Li, S., Custer, M., Preas, M. A., Rew, C. D., Cafeo, C., … & Lissauer, M. E. (2014). Successful implementation of a unit-based quality nurse to reduce central line-associated bloodstream infections. American journal of infection control, 42(2), 139-143.

Wylie, M. C., Graham, D. A., Potter-Bynoe, G., Kleinman, M. E., Randolph, A. G., Costello, J. M., & Sandora, T. J. (2010). Risk factors for central line–associated bloodstream infection in pediatric intensive care units. Infection Control & Hospital Epidemiology, 31(10), 1049-1056.

Yokoe, D. S., & Classen, D. (2008). Introduction: Improving patient safety through infection control: A new healthcare imperative. Infection Control & Hospital Epidemiology, 29(S1), S3-S11.