Microbiology Answer Note #2

Question 1 Part III The hospital microbiology laboratory presumptively identifies organisms as GAS if they are 1) beta-hemolytic on sheep blood agar, 2) sensitive to bacitracin, 3) CAMPfactor* negative, 4) inhibited by 6.5% NaC1 broth, and 5) bile-esculin negative. These techniques were not changed during last two years. Microbial susceptibilities are performed by the method of Kirby-Bauer. Table 2 lists additional surveillance/laboratory data and denominator data. TABLE 2 Surveillance/Laboratory and Denominator Data # Surgical Surgical Wound Wound Infections OR Hospital Infection RATE Month Total Grp A Strep Procedures Discharges Total Grp A Strep 1979 January 5 0 600 2950 ______ ______ February 5 0 590 2900 ______ ______ March 2 0 580 2750 ______ ______ April 2 0 560 2520 ______ ______ May 6 0 600 2700 ______ ______ June 3 0 530 2400 ______ ______ July 3 0 520 2450 ______ ______ August 3 0 490 2530 ______ ______ September 4 0 560 2690 ______ ______ October 3 0 580 2730 ______ ______ November 2 0 590 2860 ______ ______ December NA NA 500 2640 ______ ______ 1980 January NA NA 590 2970 ______ ______ February 7 0 600 2890 ______ ______ March 10 0 590 2710 ______ ______ April 10 1 620 2630 ______ ______ May 17 5 610 2720 ______ ______ June 8 0 540 2660 ______ ______ July 13 3 560 2610 ______ ______ Aug. 1-15 3 1 270 1340 ______ ______ * A substance produced by Group B Streptococci which enhances the beta-lysin production of Staphylococcus aureus. QUESTION 7 a: Calculate the monthly rate (per 1000) of all surgical wound infections and of Group A Streptococcal surgical wound infections. Graph your findings. QUESTION 7b: Interpret these findings. Based on the information you have at this point, do you think an epidemic exists? QUESTION 8: Review your answers to Question 2. Which of the explanations can be eliminated at this point? Answer Surgical Surgical Wound Wound Infections OR Hospital Infection RATE Month Total Grp A Strep Procedures Discharges Total Grp A Strep 1979 January 5 0 600 2950 ______ ______ February 5 0 590 2900 ______ ______ March 2 0 580 2750 ______ ______ April 2 0 560 2520 ______ ______ May 6 0 600 2700 ______ ______ June 3 0 530 2400 ______ ______ July 3 0 520 2450 ______ ______ August 3 0 490 2530 ______ ______ September 4 0 560 2690 ______ ______ October 3 0 580 2730 ______ ______ November 2 0 590 2860 ______ ______ December NA NA 500 2640 ______ ______ 1980 January NA NA 590 2970 ______ ______ February 7 0 600 2890 ______ ______ March 10 0 590 2710 ______ ______ April 10 1 620 2630 ______ ______ May 17 5 610 2720 ______ ______ June 8 0 540 2660 ______ ______ July 13 3 560 2610 ______ ______ Aug. 1-15 3 1 270 1340 ______ ______ * A substance produced by Group B Streptococci which enhances the beta-lysin production of Staphylococcus aureus. Question 7a: Calculate the monthly rate (per 1000) of all surgical wound infections and of Group A Streptococcal surgical wound infections. Graph your findings. To calculate the monthly rate (per 1000) of all surgical wound infections, we will use the formula: (Monthly surgical wound infections / total procedures) x 1000 January 1979: (5/600) x 1000 = 8.33 February 1979: (5/590) x 1000 = 8.47 March 1979: (2/580) x 1000 = 3.45 April 1979: (2/560) x 1000 = 3.57 May 1979: (6/600) x 1000 = 10 June 1979: (3/530) x 1000 = 5.66 July 1979: (3/520) x 1000 = 5.77 August 1979: (3/490) x 1000 = 6.12 September 1979: (4/560) x 1000 = 7.14 October 1979: (3/580) x 1000 = 5.17 November 1979: (2/590) x 1000 = 3.39 December 1979: (0/NA) x 1000 = NA January 1980: (0/NA) x 1000 = NA February 1980: (7/600) x 1000 = 11.67 March 1980: (10/590) x 1000 = 16.95 April 1980: (10/620) x 1000 = 16.13 May 1980: (17/610) x 1000 = 27.87 June 1980: (8/540) x 1000 = 14.81 July 1980: (13/560) x 1000 = 23.21 August 1980: (3/270) x 1000 = 11.11 From this, we can graph our findings: [Insert graph here] To calculate the monthly rate (per 1000) of Group A Streptococcal surgical wound infections, we will use the formula: (Monthly Group A strep infections / total procedures) x 1000 January 1979: (0/600) x 1000 = 0 February 1979: (0/590) x 1000 = 0 March 1979: