Epidemiology/Antibiogram Report - How to Interpret

by

Raymond B. Otero, Ph.D.

Consultant

220 Delmar Dr.

Richmond, KY 40475

A. Introduction

Nursing homes must be made more aware of problems that create infections, why do they occur and how they can be reduced. OBRA has indicated that nursing homes have to develop a surveillance system that answers the following questions:

1.     Can the surveillance system analyze clusters of infections?

2.     Can the surveillance system analyze changes in prevalent organisms?

3.     Can the surveillance system detect increases in the rate of infection in a timely manner?

Since most nursing homes in this country utilize reference laboratories to process their microbiological specimens, it is important that these nursing homes request certain type of information that will help them in answering the above questions. What I will be presenting to you in the following pages are examples of what laboratories should provide you with in a timely manner. If you have any questions concerning this information, please contact me at my home office.

B. Table 1 - Specimen counts by source category - current and year to date (YTD)

Table 1 gives you a monthly count of specimens and a year-to-date or cumulative 12 month total of specimens. The purpose of this table is to give you information on the number of specimens that cultured significant isolates. This will give you information on the numbers and types of specimens being submitted within your facility. You can actually plot the number and types of specimens being submitted over a period of time to see changes in frequencies. For example, if you find that the number of wound isolates are increasing over time (6 months), this could be a good indicator of rising infections in that anatomical location, or an increase in the number of cultures due to better conscientious in culturing from infected sites. Table 1 shows the results of a particular month of specimen counts and Figure 1 demonstrates how this table can be graphed for surveillance purpose and education.

Table 1 - Specimen Counts

Significant Isolates

Healthcare USA – December 2000

¹Year-to-date

If you look at Table 1, you will notice that urine specimen was the most common specimen submitted from this long term care facility. In most nursing homes, urine specimens generally make up more than 50% of the total number of specimens submitted. The year-to-date (YTD) also demonstrates the same results. If wound specimens start outnumbering urine specimens counts, this would indicate that a major problem was developing. A quick check of this table and comparing it with other months will give the facility an idea what is happening to the residents.

If you look at Figure 1, a simple graph can be developed to show if there are beginning problems within your facility. For example, upon examination of Figure 1, you will see that there is an increase in wound isolates over a 6 month period. Perhaps a reexamination of the charts and residents may be appropriate to see what is really going on. There are possibly three reasons why this is occurring. First, there may be an increase awareness of culturing areas which demonstrate infections (i.e., purulence), second there are significant rises in wound infections, or third, surveillance cultures were being performed to rule out a particular organism (i.e., MRSA).

C. Table 2 - Facility totals by organisms - current and YTD

Table 2 tabulates the total number of isolates for the current month and year-to-date. Table 2 provides you with a total number (count) and percentage of the total number of isolates. For example, Table 2 shows that in December 2000, this facility had a total number of 75 isolates. Escherichia coli was cultured 26 times for a percentage of 34.7 (26/75 x 100 = 34.7%). The YTD (01-01-00 – 12-31-00) showed that E. coli was cultured 223 times for a percentage of 35% (223/637 x 100 = 35%). This table can be used to compare the total number of isolates that were cultured in your facility over months. For example, if the total number of isolates per month in your facility averaged 45 over 2000, and now you are averaging 65 for the last half of 2000, then you need to look at the remaining tables in the epidemiology report to see what is going on.

Table 2 - Facility total by organisms

Healthcare USA – December 2000

Graphs can also be produced from Table 2 (Figure 2). You may also want to graph a certain type of organism over a period of time, e.g., MRSA isolates (Figure 3) to determine cluster or rises in infections over time. Another example for the use of Table 2 is performing surveillance on the incidence of potentially resistant organisms (Figure 4). As you all know by now, there are increases of multi-resistant organisms in health care and the Centers for Disease Control and Prevention (CDC) have issued an alert on vancomycin-resistant Enterococcus faecalis. If you see these isolates continually rising, the chances for obtaining a resistant form increases. Pseudomonas aeruginosa, a gram negative rod often found in the environment is now one of the major causes of infections in the compromising host. This organism is intrinsically resistant to many antibiotics but we are now seeing it develop resistance to aminoglycosides and other major antibiotics. Table 2 can be used as a good surveillance tool to show you what is happening over time.

D. Table 3 - Incidence of organisms within Source category - current and YTD

Table 3 provides you with information concerning where the organisms listed in Table 2 are being isolated (source). Since urine is a common specimen submitted for microbiological analysis, I will use it as an example. There were a total of 54 isolates cultured from urine (bottom figure under urine). Enterococcus was cultured 12 (number in parenthesis) times, Escherichia coli 26 times, and etc. The number not in parenthesis is the percent of the total number isolated from urine (i.e., Escherichia coli = 26/54 x 100 = 48.1%). This means of the total isolates cultured in urine, Escherichia coli made up 48.1% of the total number.

Table 3 - Incidence of Organisms within source category

Healthcare USA

December 2000

¹Total number of isolates

²Percent of total within source category (respiratory)

How important is Table 3? Very. For example, since OBRA 1995 wants every nursing home to determine causes of infection in order to reduce them, one can look for possible explanation of why your residents are developing urinary tract infection. Examining Table 3, one sees that 83.3% of all of the isolates in urine were from enteric sources (Enterococcus 12, Enterobacter cloacae 4, Escherichia coli 26, Klebsiella pneumoniae 2, and Providencia rettgeri 1, make up 45/54 = 83.3%). This should indicate to the person involved in staff development that more emphasis must be placed on perianal cleansing of the residents. Graphic displays of the data in Table 3 can accentuate findings (Figure 5). As Figure 5 indicates, there has been a continual rise in enteric isolates in all 4 quarters for 2000. Figure 6 shows how surveillance can be performed using graphic tools. As you can see by this figure a steady rise of MRSA isolates occurred in July, August and September of 2000. However, through recognition and re-emphasizing Standard Precautions, this facility was able to reduce the numbers. Figure 7 shows how you can get fancy with graphics. Using MRSA isolates as an example, one can determine organism vs. source and pinpoint a specific anatomical region. These graphics really enhance presentations.

E. Table 4 - Distribution of Isolates by Source Category - current and YTD

Table 4 tabulates the distribution of isolates by source. For example, 70.6% of all Enterococcus isolated within the facility came from urine specimens (17 Enterococcus were isolated = 12/17 x 100 = 70.6%), 54.2% of all Escherichia coli isolates (26/48 x 100 = 54.2%) were from urine. Table 4 gives you a quick look on what source a particular organism was found. Again, if you find that the majority of isolates from urines or wounds are enterics, the residents are probably indigenously infecting themselves.

Note: The year-to-date tabulations that will follow each current table can be interpreted in the same manner.

Table 4 - Distribution of Isolates by Source

Healthcare USA

December 2000

¹Total number of isolates

²Percent of total by source

F. Table 5 - Infection Control Detail by Organism - current or YTD

Table 5 needs to be kept confidential. This table lists the patient’s name, ID number, organism isolated and source. This table will also list the referring physician. The organisms will be listed alphabetically. You can use this table to show what area of your facility is submitting specimens that contain MRSA. Also, you can make evaluation of your staff on perianal cleansing of your residents by looking for the enteric isolates and the location of the residents. Perhaps this may cut down on group participation in-service educational programs and go one-on-one in problem areas. This is an excellent table to help infection control practitioners determine location of problems within their facility.

Table 5 - Infection Control Detail by Organism

Healthcare USA

December 2000

¹Make certain that staff members place the location of the resident on the requisition form.

²Make certain that staff members place the anatomical location of the source on the requisition form.

F. Table 6 - Infection Control Detail by location - current and YTD

Table 6 also needs to be kept confidential because of patient name listing. This table accomplishes what OBRA’s 1995 guidelines that each facility must be able to determine clusters of infections. This table gives you a quick location of where organisms are being isolated. The locations are placed on the first column in sequential order.

Table 6 - Infection Control Detail by Location

Healthcare USA

December 2000

¹Make certain that staff members place the location of the resident on the requisition form.

²Make certain that staff members place the anatomical location of the source on the requisition form.

G. Table 7 - Infection Control Detail by Patient - current and YTD

This table should also be kept confidential. Table 7 is just a rearrangement of data. The resident’s are listed in alphabetical order for easy access. One good use of this table is to show the facility which resident is constantly developing infections over time. For example, prophylactic administration of antibiotics for reducing urinary tract infections may indicate several types of organisms being isolated from a particular patient over time. It is interesting to note that Licensure and Regulation is looking for persistent infections among residents over time such as urinary tract infections. This table can be shown to the infection control/quality review committee.

Table 7 - Infection Control Detail by Patient

Healthcare USA

December 2000 

¹Make certain that staff members place the location of the resident on the requisition form.

²Make certain that staff members place the anatomical location of the source on the requisition form.

H. Table 8 - Infection Control Detail by Source Category - current

The tables that follow Table 7 in the epidemiology report are summation tables. For example Table 8 summarizes all the urine isolates with organism, date of report, patient ID, location, patient name, referring physician, and source. There are 7 of these tables and they summarize all the isolates from blood, body fluids, respiratory, stools, urine, wounds and others. The organisms are listed in the first column in alphabetical order.

Table 8 - Infection Control Detail by Source

Healthcare USA

Urine

It is imperative that the facility fills out the requisition form in the following manner:

1. Patient’s name*

2. Date of obtainment of specimen

3. Time of obtainment of specimen

4. Specific site, i.e., right ankle (left side) decubitus*

5. Patient ID number from facility for identification for surveillance

6. Referring physician*

7. Specific location of resident (for facility surveillance)*

*These are important demographics so that your epi reports are complete.

Table 8 above can be used to determine specific type organism being isolated over time within the facility. For example, if I wanted to determine the number of isolates of MRSA from specific residents over time, I would get a summary report (6 months or 12 months) from the reference laboratory and plot them on a graph. See Figure 8 to show you what I mean.

As you can see, there were many isolates obtained during the last 6 months of 2000, however, you will also notice that fewer residents were involved. If you also separate the colonized from the infected (see Figure 7), the numbers would also in all probability be less. The number of isolates of MRSA is not as important as to the explanation of its occurrence.

I feel that these tables and figures given above will accomplish OBRA’s 1995 goals. If you have any questions, please do not hesitate in calling me at my home office (859-623-3973). My e-mail address is: belinotero@aol.com. My web site is: http://www.cinetwork.com/otero.

Infection Control is an exciting field. It can be performed by facilities at a reasonable cost. With monitory fines coming up, each facility must be prepared to defend their system. Let me help you.

Antibiogram Report

A. Introduction

The antibiogram report accompanies the epidemiology report. This report is important for the Infection Control Practitioner (ICP), Physician, Pharmacists and the Nurses on the floors. The antibiogram report contains the following information:

1. Organisms isolated

2. Source (blood, urine, wound)

3. Number of isolates (ISO)

4. List of antibiotics tested*

5. Percent susceptible (100%, 75%, 67%, etc.)

B. Codes (abbreviations)

Table 10 will interpret the codes for the antibiotics:

Table 10 - Code Identification