Df2.2-;::>:~47 /'o/Q/i 202-0-'. 0':.'$f.Y'._Qi~-_IG
120) Printed in
THE Jrn:TfrNLL OF URcLoG--,-{
Copyright © 1978
The 1llilliarns & 'Nilkir1s Cc.
EVALUATION OF
DIP-SLIDE IN A UNIVERSITY OUTPATIENT SERVICE
MARY JANE MARTIN
MARYAI~NE B. MCGUCKIN*
AND
From the Medical Technology Department, School of Allied Medical Professions, University of Pennsylvania and Infectious Disease Section, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
ABSTRACT
Initial and followup urine specimens from patients in an outpatient service of a university hospital with the diagnosis of presumptive urinary tract infection were processed by the dip-slide system and the conventional calibrated loop procedure. Evaluation of the dip-slide system included not only microbiological comparison but also the feasibility of the adaptation of this system to a clinic working area. Complete microbiological agreement between the 2 methods was approximately 50 per cent. Disagreement was caused largely by improper inoculation, quantitation and interpretation of the dip-slide. It has been our experience that the dip-slide cannot be used effectively as a screening tool in a population with a high incidence of urinary tract infection. The use of laboratory personnel along with proper specimen collecting instructions increased the reliability of the dip-slide system. Our data suggest that the results obtained should be evaluated carefully along with the clinical impression in complicated cases of urinary tract infections. Urinary tract infection is a long recognized problem in health care systems. The prevalence of bacteriuria in the female patient increases with age and sexual activity. 1 If symptoms exist some of the common ones in the chronically ill patient are low back pain, nocturia, easy fatigability, weight loss and growth disturbances (in children). In the acutely ill patient hematuria, fever, chills, dysuria, urgency and frequency are more common. 2 When urinary tract infection is considered to be existent these symptoms are not sufficient to make a diagnosis, since they are non-specific and could have other causes. To diagnose urinary tract infection a significant bacteriuria must be found. With the recognition of the problem of bacteriuria comes the question of what is the best and most practical means to culture urine. The conventional calibrated loop method has been in use since 1960.:i With this method urine specimens must be transported to the laboratory, causing a delay in culturing and the possibility of increased bacteriological counts owing to multiplication of bacteria during transportation. Because of this fact there has been a search for a product that would eliminate the delay in inoculation. One procedure considered for this purpose is the dip-slide. The agar-coated dip-slide is attached to a cap that closes onto a tube. An advantage of the dip-slide is that inoculation can be performed in the clinic. The purpose of our study was to evaluate the feasibility of using the dip-slide at our hospital in a clinic situation. A hospital walk-in clinic was used as a model to see if the slide could be used effectively. A walk-in clinic is an adjunct to the emergency ward for ambulatory patients not requiring immediate patient care. Microbiological evaluation of the method was not our intention, since this has been performed by Ellner and Papachristos. 4
clinic, while the conventional method was performed by laboratory personnel. Group 2 consisted of 85 female clinic patients with no definite predisposition to urinary tract infection. For this group the dip-slide and the conventional inoculations were performed by laboratory personnel. Interpretation of all cultures was performed by laboratory personnel. Collection of specimens. The urine specimens for the study were collected in clean-catch midstream urine containers. The dip-slides were inoculated immediately after voiding of specimens, whereas the conventional method was delayed 1 to 2 hours by transportation to the laboratory. Cultures. Specimens processed by the conventional method were inoculated on a colistin/nalidixic acid/MacConkey biplate using an 0.001 :mJ. calibrated loop. Colonies were counted and were considered significant if the count for a pathogenic organism was 100,000 colony-forming units or more per ml. urine. 5 The dip-slide was inoculated by dipping the slide into freshly voided urine, then touching the tip of the slide to a paper towel to remove excess urine. The slide was then
D
AGREEMENT
E3 QUALITATIVE DISAGREEMENT
Ill QUANTITATIVE
MATERIALS AND METHODS
There were 116 patient samples included in this study. The patients were between 17 and 40 years old. They were divided into 2 groups. Group 1 consisted of 31 female patients who had been treated for urinary tract infection previously but had never undergone a followup culture. Inoculation of the dipslide for this group was performed by the staff in the walk-in Accepted for publication October 7, 1977. * Requests for reprints: Infectious Disease Section, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104.
FIG. 1. Comparison of results with dip-slide and conventional culturing methods.
193
194
MARTIN AND MCGUCKIN
¾
-GROUP I rz:::a GROUP 2
60 50
40 30 20 10
o~-AGREEMENT
QUALITATIVE DISAGREEMENT
QUANTITATIVE DISAGREEMENT
Fm. 2. Comparison of results in groups 1 and 2. In group 1 dip-slides were inoculated by clinic personnel. In group 2 dip-slides were inoculated by laboratory personnel. GROUP 1
GROUP1
gram -
gram+
Dipslide Organisms /m I 104
... ,. GROUP 2
GROUP 2
gram+
gram -
> 105
105
Dipslide Organisms/ml
104
10 3
10 4
10 5
>10 5
103
10 4
10 5
>10 5
Loop Method Organisms /ml Fm. 3. Regression curves show total specimen data (118), excluding 17 negative results, comparing dip-slide to conventional culturing method.
replaced in its holder. In this study the dip-slides had MacConkey agar on one side and Cled plus polymyxin B on the other side. The dip-slide and the conventional method were incubated at 37C and read at 24 and 48 hours. Identification of organisms was based on the gram stain, colony morphology and biochemical characteristics. 5 RESULTS
Results with the dip-slide and the conventional culturing methods were compared (fig. 1). Qualitative disagreement (bacterial type) was 37 per cent and quantitative disagreement (bacterial counts) was 11.2 per cent. Total agreement between both methods was 51. 7 per cent. Agreement was considered to exist in mixed cultures when the predominant organism was
isolated by both methods. Organisms isolated frequently were members of the Enterobacteriaceae family, Pseudomonas, enterococci and yeast. Staphylococcus epidermidis and diphtheroids were the most frequent gram-positive organisms isolated. Results obtained in each group of patients were compared (fig. 2). Agreement between the culturing methods was 42 per cent for group 1 and 55 per cent for group 2. Qualitative disagreement was 51.5 per cent for group 1 and 37.8 per cent for group 2. In group 1, 39 per cent of the qualitative disagreement was caused by gram-positive organisms in the 103 to 10 5
5
6
11
TOTAL
10
16
26
TOTAL
45
9
54
I
Fm. 4. Total specimen data (118), excluding 17 negative results
reduction in the disagreement in gram-positive organisms of the 103 to
120) Printed in
THE Jrn:TfrNLL OF URcLoG--,-{
Copyright © 1978
The 1llilliarns & 'Nilkir1s Cc.
EVALUATION OF
DIP-SLIDE IN A UNIVERSITY OUTPATIENT SERVICE
MARY JANE MARTIN
MARYAI~NE B. MCGUCKIN*
AND
From the Medical Technology Department, School of Allied Medical Professions, University of Pennsylvania and Infectious Disease Section, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
ABSTRACT
Initial and followup urine specimens from patients in an outpatient service of a university hospital with the diagnosis of presumptive urinary tract infection were processed by the dip-slide system and the conventional calibrated loop procedure. Evaluation of the dip-slide system included not only microbiological comparison but also the feasibility of the adaptation of this system to a clinic working area. Complete microbiological agreement between the 2 methods was approximately 50 per cent. Disagreement was caused largely by improper inoculation, quantitation and interpretation of the dip-slide. It has been our experience that the dip-slide cannot be used effectively as a screening tool in a population with a high incidence of urinary tract infection. The use of laboratory personnel along with proper specimen collecting instructions increased the reliability of the dip-slide system. Our data suggest that the results obtained should be evaluated carefully along with the clinical impression in complicated cases of urinary tract infections. Urinary tract infection is a long recognized problem in health care systems. The prevalence of bacteriuria in the female patient increases with age and sexual activity. 1 If symptoms exist some of the common ones in the chronically ill patient are low back pain, nocturia, easy fatigability, weight loss and growth disturbances (in children). In the acutely ill patient hematuria, fever, chills, dysuria, urgency and frequency are more common. 2 When urinary tract infection is considered to be existent these symptoms are not sufficient to make a diagnosis, since they are non-specific and could have other causes. To diagnose urinary tract infection a significant bacteriuria must be found. With the recognition of the problem of bacteriuria comes the question of what is the best and most practical means to culture urine. The conventional calibrated loop method has been in use since 1960.:i With this method urine specimens must be transported to the laboratory, causing a delay in culturing and the possibility of increased bacteriological counts owing to multiplication of bacteria during transportation. Because of this fact there has been a search for a product that would eliminate the delay in inoculation. One procedure considered for this purpose is the dip-slide. The agar-coated dip-slide is attached to a cap that closes onto a tube. An advantage of the dip-slide is that inoculation can be performed in the clinic. The purpose of our study was to evaluate the feasibility of using the dip-slide at our hospital in a clinic situation. A hospital walk-in clinic was used as a model to see if the slide could be used effectively. A walk-in clinic is an adjunct to the emergency ward for ambulatory patients not requiring immediate patient care. Microbiological evaluation of the method was not our intention, since this has been performed by Ellner and Papachristos. 4
clinic, while the conventional method was performed by laboratory personnel. Group 2 consisted of 85 female clinic patients with no definite predisposition to urinary tract infection. For this group the dip-slide and the conventional inoculations were performed by laboratory personnel. Interpretation of all cultures was performed by laboratory personnel. Collection of specimens. The urine specimens for the study were collected in clean-catch midstream urine containers. The dip-slides were inoculated immediately after voiding of specimens, whereas the conventional method was delayed 1 to 2 hours by transportation to the laboratory. Cultures. Specimens processed by the conventional method were inoculated on a colistin/nalidixic acid/MacConkey biplate using an 0.001 :mJ. calibrated loop. Colonies were counted and were considered significant if the count for a pathogenic organism was 100,000 colony-forming units or more per ml. urine. 5 The dip-slide was inoculated by dipping the slide into freshly voided urine, then touching the tip of the slide to a paper towel to remove excess urine. The slide was then
D
AGREEMENT
E3 QUALITATIVE DISAGREEMENT
Ill QUANTITATIVE
MATERIALS AND METHODS
There were 116 patient samples included in this study. The patients were between 17 and 40 years old. They were divided into 2 groups. Group 1 consisted of 31 female patients who had been treated for urinary tract infection previously but had never undergone a followup culture. Inoculation of the dipslide for this group was performed by the staff in the walk-in Accepted for publication October 7, 1977. * Requests for reprints: Infectious Disease Section, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104.
FIG. 1. Comparison of results with dip-slide and conventional culturing methods.
193
194
MARTIN AND MCGUCKIN
¾
-GROUP I rz:::a GROUP 2
60 50
40 30 20 10
o~-AGREEMENT
QUALITATIVE DISAGREEMENT
QUANTITATIVE DISAGREEMENT
Fm. 2. Comparison of results in groups 1 and 2. In group 1 dip-slides were inoculated by clinic personnel. In group 2 dip-slides were inoculated by laboratory personnel. GROUP 1
GROUP1
gram -
gram+
Dipslide Organisms /m I 104
... ,. GROUP 2
GROUP 2
gram+
gram -
> 105
105
Dipslide Organisms/ml
104
10 3
10 4
10 5
>10 5
103
10 4
10 5
>10 5
Loop Method Organisms /ml Fm. 3. Regression curves show total specimen data (118), excluding 17 negative results, comparing dip-slide to conventional culturing method.
replaced in its holder. In this study the dip-slides had MacConkey agar on one side and Cled plus polymyxin B on the other side. The dip-slide and the conventional method were incubated at 37C and read at 24 and 48 hours. Identification of organisms was based on the gram stain, colony morphology and biochemical characteristics. 5 RESULTS
Results with the dip-slide and the conventional culturing methods were compared (fig. 1). Qualitative disagreement (bacterial type) was 37 per cent and quantitative disagreement (bacterial counts) was 11.2 per cent. Total agreement between both methods was 51. 7 per cent. Agreement was considered to exist in mixed cultures when the predominant organism was
isolated by both methods. Organisms isolated frequently were members of the Enterobacteriaceae family, Pseudomonas, enterococci and yeast. Staphylococcus epidermidis and diphtheroids were the most frequent gram-positive organisms isolated. Results obtained in each group of patients were compared (fig. 2). Agreement between the culturing methods was 42 per cent for group 1 and 55 per cent for group 2. Qualitative disagreement was 51.5 per cent for group 1 and 37.8 per cent for group 2. In group 1, 39 per cent of the qualitative disagreement was caused by gram-positive organisms in the 103 to 10 5
5
6
11
TOTAL
10
16
26
TOTAL
45
9
54
I
Fm. 4. Total specimen data (118), excluding 17 negative results
reduction in the disagreement in gram-positive organisms of the 103 to
