ANESTH ANALG 58141-142, 1979
Stopcock Contamination Gale E. Dryden, MD* and Joseph Brickler, BSt The source of septicemia as nosocomial infection is often difficult to define14 and is frequently associated with high m ~ r t a l i t y Stopcocks .~ are commonly used in the practice of anesthesia to assist in pressure monitoring and for the administration of drugs, fluids, and transfusions. We examined their potential as a source for systemic contamination.
Methods First Study Cultures The first study included 103 stopcocks that had been used by the anesthesiologist during the operative period and were removed upon the patient’s arrival in the recovery room. The fluid stream channels were cultured by flushing with 10 ml of tryptic soy nutrient broth and aerobically incubating for 48 hours. Visual clouding of the broth was interpreted as positive contamination. Fourteen unused stopcocks (controls) were cultured in the same manner.
Second Study Cultures A second study of 49 used and 4 unused control stopcocks were collected and cultured in a similar manner, but the broth was added to 15 ml of melted tryptic soy agar mixed and poured into a sterile Petri dish which was incubated aerobically at 35 C for 48 hours. The plates were examined macroscopically and colonies checked under a 30X disecting stereomicroscope. The number of colonies and the types of organisms were documented.
ResuIts All unused control stopcocks were negative for growth. Fifty positive cultures resulted from the first Chief of Anesthesiology, Wishard Memorial Hospital; Assistant Professor Anesthesiology, Indiana University School of Medicine. t Microbiology Laboratory, Wishard Memorial Hospital. Received from the Department of Anesthesiology, Wishard Memorial Hospital, 1001 West Tenth Street, Indianapolis, Indiana 46202. Accepted for publication November 24, 1978. Address reprint requests to Gale E. Dryden, MD.
103 stopcocks that were cultured in broth only (48.5%). The degree of cloudiness could not be inter-
preted as a method for determining the degree of contamination. Not all positive cultures were studied for organism type. However, of those identified there was a preponderance of Staphylococcus epidermidis coagulase negative. Other types of organisms included aerobic bacilli, enterococcus, and diphtheroids. Twenty positive cultures were obtained from the 49 stopcocks cultured with agar plates (40%). On the 20 plates the numbers of organisms were: one had four colonies; one had five colonies; one had six colonies; one had seven colonies; one had 13 colonies; one had 14 colonies; one had 16 colonies; one had 27 colonies; two had two colonies; two had three colonies; and eight had one single colony. The types of organisms included: Micrococcus on two plates; S. epidennidis on 19 plates; Gram-negative bacillus (nonfermenting) on one plate; Staphylococcus aureus on two plates; and Escherichia coli on one plate. Eighty-five of the stopcocks in the study were not packaged with limb covers; 42 (40%) of these were positive. Sixty-seven stopcocks were originally packaged with covers; 28 (41.8%) were positive. Thirtyfive (52%) of the 67 stopcocks originally supplied with limb covers had the original cover or a syringe on the side limb when cultures were made; of this group 16 (45%) were positive. Thirty-two (48%) of the 67 had the side limb uncovered at the time of culture; of these 12 (37.5%) were positive.
Discussion These studies were camed out over a 3-year period. During this interval personnel were aware of concern about stopcock contamination and were asked to practice special care in their use. In spite of this knowledge numerous breaks in sterile technique were observed, as for example, allowing an uncovered limb of the stopcock to fall and touch a nonsterile area, or allowing the finger tips to contact an area of the stopcock that would later be contacted by a syringe or intravenous line. The small size and the short limbs on stopcocks make them tedious to handle properly; however, stopcocks used by a few individual anesthesiologists in the study had consistantly negative cultures. Prevention of contamination could be achieved under clinical conditions. The providing of cover caps with the stopcocks did not decrease the incidence of contamination. The ANESTHESIA AND ANALGESIA Vol 58, No 2, Mar-Apr 1979
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CLINICAL REPORTS
covers were often dropped or discarded; in some cases a syringe was used to act as a cover substitute. There was an overall contamination rate of 46% in the combined studies, compared to 41.8% of stopcocks initially provided with covers. The high incidence of organisms common to the skin suggests that the fingers of the anesthetist are a common source of contamination. There was no readily defined relationship between the incidence of contamination and duration of use in the operating room. Our method of culture did not ensure or validate that all organisms in the stopcock were removed. We are also aware that the number of colony-forming units does not necessarily reflect the number of organisms present. One colony may form from one or a few individual bacterial cells. No attempt was made to determine whether contamination extended downstream from the stopcock. During the study periods one patient developed S. epidemidis septicemia postoperatively, but direct relationship to the use of the stopcock could not be established because the culture was discarded before there was awareness of the patient’s problem. There
were no other cases of septicemia among the study group. There was not adequate patient follow-up to evaluate a possible relationship between phlebitis and contaminated stopcocks. In summary, we found that routine use of stopcocks during anesthesia for the administration of fluids and drugs was associated with a contamination rate of 46%. ACKNOWLEDGMENT Acknowledgment is made to Robert Bottoroff and Sue Benecke for their assistance in this study. REFERENCES 1. Weinstein RA, Stamm WE, Kramer L, et al: Pressure monitoring devices overlooked source of nosocomial infection. JAMA 236936-938, 1976 2. Wilkins DG, Bruten DM, Caddy ED: Sterility of fluid filled lines for pressure measurements. Anaesthesia 27403-407, 1972 3. Walton JR, Shapiro BA, Harrison RA, et al: Serratia bacteremia from mean arterial pressure monitors. Anesthesiology 43:113114, 1975 4. Rlouffe JF, Brown DG, Silva J Jr: Nosocomial outbreak of candida parapsilosis fungemia related to intravenous infusions. Arch Intern Med 1371686-1689, 1977 5. Setia U, Gross PA: Bacteremia in a community hospital: spectrum and mortality. Arch Intern Med 137:1698-1701, 1977
Erratum In the paper “Pharmacokinetics of Drugs Administered Intravenously” by Carl C. Hug, Jr. (Anesthesia and Analgesia 57: 704-723, 1978)there is an error on p 722, Fig 10. The scale of the ordinate (vertical axis) is incorrect. Instead of a logarithmic scale as shown, it should be arithmatic; that is, the numbers should read from the bottom up 0,1, 2, 3, 4, 5, 6.C,“ will equal 3 at an infusion rate of Q and will equal 6 at an infusion rate of 2Q.
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ANESTHESIA AND ANALGESIA Vol 58, No 2, Mar-Apr 1979
Stopcock Contamination Gale E. Dryden, MD* and Joseph Brickler, BSt The source of septicemia as nosocomial infection is often difficult to define14 and is frequently associated with high m ~ r t a l i t y Stopcocks .~ are commonly used in the practice of anesthesia to assist in pressure monitoring and for the administration of drugs, fluids, and transfusions. We examined their potential as a source for systemic contamination.
Methods First Study Cultures The first study included 103 stopcocks that had been used by the anesthesiologist during the operative period and were removed upon the patient’s arrival in the recovery room. The fluid stream channels were cultured by flushing with 10 ml of tryptic soy nutrient broth and aerobically incubating for 48 hours. Visual clouding of the broth was interpreted as positive contamination. Fourteen unused stopcocks (controls) were cultured in the same manner.
Second Study Cultures A second study of 49 used and 4 unused control stopcocks were collected and cultured in a similar manner, but the broth was added to 15 ml of melted tryptic soy agar mixed and poured into a sterile Petri dish which was incubated aerobically at 35 C for 48 hours. The plates were examined macroscopically and colonies checked under a 30X disecting stereomicroscope. The number of colonies and the types of organisms were documented.
ResuIts All unused control stopcocks were negative for growth. Fifty positive cultures resulted from the first Chief of Anesthesiology, Wishard Memorial Hospital; Assistant Professor Anesthesiology, Indiana University School of Medicine. t Microbiology Laboratory, Wishard Memorial Hospital. Received from the Department of Anesthesiology, Wishard Memorial Hospital, 1001 West Tenth Street, Indianapolis, Indiana 46202. Accepted for publication November 24, 1978. Address reprint requests to Gale E. Dryden, MD.
103 stopcocks that were cultured in broth only (48.5%). The degree of cloudiness could not be inter-
preted as a method for determining the degree of contamination. Not all positive cultures were studied for organism type. However, of those identified there was a preponderance of Staphylococcus epidermidis coagulase negative. Other types of organisms included aerobic bacilli, enterococcus, and diphtheroids. Twenty positive cultures were obtained from the 49 stopcocks cultured with agar plates (40%). On the 20 plates the numbers of organisms were: one had four colonies; one had five colonies; one had six colonies; one had seven colonies; one had 13 colonies; one had 14 colonies; one had 16 colonies; one had 27 colonies; two had two colonies; two had three colonies; and eight had one single colony. The types of organisms included: Micrococcus on two plates; S. epidennidis on 19 plates; Gram-negative bacillus (nonfermenting) on one plate; Staphylococcus aureus on two plates; and Escherichia coli on one plate. Eighty-five of the stopcocks in the study were not packaged with limb covers; 42 (40%) of these were positive. Sixty-seven stopcocks were originally packaged with covers; 28 (41.8%) were positive. Thirtyfive (52%) of the 67 stopcocks originally supplied with limb covers had the original cover or a syringe on the side limb when cultures were made; of this group 16 (45%) were positive. Thirty-two (48%) of the 67 had the side limb uncovered at the time of culture; of these 12 (37.5%) were positive.
Discussion These studies were camed out over a 3-year period. During this interval personnel were aware of concern about stopcock contamination and were asked to practice special care in their use. In spite of this knowledge numerous breaks in sterile technique were observed, as for example, allowing an uncovered limb of the stopcock to fall and touch a nonsterile area, or allowing the finger tips to contact an area of the stopcock that would later be contacted by a syringe or intravenous line. The small size and the short limbs on stopcocks make them tedious to handle properly; however, stopcocks used by a few individual anesthesiologists in the study had consistantly negative cultures. Prevention of contamination could be achieved under clinical conditions. The providing of cover caps with the stopcocks did not decrease the incidence of contamination. The ANESTHESIA AND ANALGESIA Vol 58, No 2, Mar-Apr 1979
141
CLINICAL REPORTS
covers were often dropped or discarded; in some cases a syringe was used to act as a cover substitute. There was an overall contamination rate of 46% in the combined studies, compared to 41.8% of stopcocks initially provided with covers. The high incidence of organisms common to the skin suggests that the fingers of the anesthetist are a common source of contamination. There was no readily defined relationship between the incidence of contamination and duration of use in the operating room. Our method of culture did not ensure or validate that all organisms in the stopcock were removed. We are also aware that the number of colony-forming units does not necessarily reflect the number of organisms present. One colony may form from one or a few individual bacterial cells. No attempt was made to determine whether contamination extended downstream from the stopcock. During the study periods one patient developed S. epidemidis septicemia postoperatively, but direct relationship to the use of the stopcock could not be established because the culture was discarded before there was awareness of the patient’s problem. There
were no other cases of septicemia among the study group. There was not adequate patient follow-up to evaluate a possible relationship between phlebitis and contaminated stopcocks. In summary, we found that routine use of stopcocks during anesthesia for the administration of fluids and drugs was associated with a contamination rate of 46%. ACKNOWLEDGMENT Acknowledgment is made to Robert Bottoroff and Sue Benecke for their assistance in this study. REFERENCES 1. Weinstein RA, Stamm WE, Kramer L, et al: Pressure monitoring devices overlooked source of nosocomial infection. JAMA 236936-938, 1976 2. Wilkins DG, Bruten DM, Caddy ED: Sterility of fluid filled lines for pressure measurements. Anaesthesia 27403-407, 1972 3. Walton JR, Shapiro BA, Harrison RA, et al: Serratia bacteremia from mean arterial pressure monitors. Anesthesiology 43:113114, 1975 4. Rlouffe JF, Brown DG, Silva J Jr: Nosocomial outbreak of candida parapsilosis fungemia related to intravenous infusions. Arch Intern Med 1371686-1689, 1977 5. Setia U, Gross PA: Bacteremia in a community hospital: spectrum and mortality. Arch Intern Med 137:1698-1701, 1977
Erratum In the paper “Pharmacokinetics of Drugs Administered Intravenously” by Carl C. Hug, Jr. (Anesthesia and Analgesia 57: 704-723, 1978)there is an error on p 722, Fig 10. The scale of the ordinate (vertical axis) is incorrect. Instead of a logarithmic scale as shown, it should be arithmatic; that is, the numbers should read from the bottom up 0,1, 2, 3, 4, 5, 6.C,“ will equal 3 at an infusion rate of Q and will equal 6 at an infusion rate of 2Q.
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