Results of survey of blood culture methods: Part I

7158D

August 15, 1986

Vol. 8, No. 16

Results of Survey of Blood Culture Methods: Part I Karen Sue C. Kehl, Ph.D. Mounr Sinai Medical Cenrer Deparlment of Parholog} Milwaukee, Wisconsin53201

The response to the blood culture survey was excellent with responses received from 288 laboratories. The results will be presented in two parts. The results published in this issue concern specimen collection, culture techniques, and rapid organism identification and susceptibility testing. The next issue will contain survey results addressing Isolator cultures, fungus cultures, positivity rates, contamination rates, and charges. In summary, the number of laboratories using each system were: BACTEC-125; Isolater-16; Isolator in combination with routine broth culture-29; Roche Septi-Chek-26; and other broth culture systems-92. Most laboratories use both isopropyl alcohol and povidone iodine to disinfect the venipuncture site and collect 5-10 mL of blood from adults with needle and syringe. All laboratories examine the bottles at least once per day, however II4 (54%) perform blind subcultures and only 27 (16%) perform blind Gram stains. One hundred eighty-six (76%) laboratories perform direct antimicrobial susceptibility tests, while only 77 (31%) perform rapid direct identification. The following are the questions presented in the Survey with respective answers; numbers will usually indicate the number of laboratories answering in that category. Numbers may not add up to total respondents due to lack of response.

1. Type of laboratory

2. If hospital laboratory, specify type

In This Issue 274 3 10 2

___198 22 40 9 ~ 5

Hospital Clinic Private Other

Community VA or other government Medical school or affiliate Childrens Other (corporate- 1, rehabilitation- 1, private-2)

3. If hospital laboratory, how many beds?

<200 201-400 401-700 >700

CMNEEJ

X(16)117-126.1986

Communi~

Medical School

VA

Childrens

Other

46 82 43 20

1 10 19 10

3 6 8 4

I 6

3 6 2 1

Elae\wr

Results of Survey of Blood Culture Methods. Part I . . . . . . .117 First of two installments presenting the results of the blood culture survey (CMN 8(3)) Training Programs in Clinical Microbiology at the Baccalaureate Level: Minimal Competencies and Programmatic Approval . . . . . . . . . . . . . . . . . . . .124 Development of the approval processfor programs for training microbiology technologists Case Report. . . . . . . . . . . . . . . . . .125

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4. Number of blood cultures done per year for routine bacteriologic culture. Nutnber of Beds

Number of Cultures Community Hospital ’ 2OlJfOO

<200

7 37 37

32 11 2

c1500 1501-3500 350 l-8000 >8000

401-700

> 700

2 27 13

1 2 13

VA Hospital 2

Cl500 1501-3500 3501-8000 >8000

1 3

2 2

Medical School ASJiliated Hospitals Cl500 1501-3500 3501-8000 >8000

4 4 8

1 5 3

1

1 10

Childretrs Hospital 8000

1

1 3 3

1

2

2 1

3

Other Hospitals Cl500 1501-3500 3501-8000 >8000

5. Who routinely collects blood samples for culture’? (The following numbers reflect multiple answers from respondents.) 72 23 3 159 17 89

Physicians/residents (41 of these are medical school or affiliates) Nurse IV team Wenipuncture team Microbiology technologists Clinical laboratory technologists

6. What site is routinely recommended for venipuncture? 248 1 2

118

Antecubital fossa Arterial lines Catheters

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7. What sites are not recommended for venipuncture? 39 122

2

Leg (groin) IV lines

2

Shunts Heparin locks

8. What is used to disinfect the venipuncture site? The following numbers reflect multiple answers from respondents. 110 10 155 25 160

Isopropyl alcohol Ethanol Povidone iodine (e.g., Betadine) Tincture of iodine Multiples of above in series

9. What method is used to obtain the blood? (The following numbers reflect multiple answers from respondents.) 221 38 41 2 18 39

Syringe Directly into Isolator collection tube Evacuated sterile tube (with sodium polyanethol sulfonate) 1 ~ Sterile tube with other anticoagulant, specify Heparin Not specified 1 Double needle collection set into culture medium Directly into blood culture medium container (e.g., B-D tube or bottle)

10. What total volume of blood do you recommend be collected for bacteriologic culture?

Adults Pediatrics Neonates

<5 mL

5-10 mL

1 I-15 mL

lb-20 mL

>20 mL

13 160 197

205 66 1

72 3

41

13

11. Indicate the number and type(s) of broth culture media inoculated for routine bacteriologic culture (other than Isolator cultures) and whether or not the bottles are vented, contain CO*, and were commercially purchased. See Question 22 regarding Isolator system blood cultures. 124 139 20 25 18 9 14 14

_

g 5 7 1 7 7 6 4 1 1 2 1 2 4 4 3

BACTEC broth, aerobic BACTEC broth, anaerobic BACTEC broth, hypertonic Roche SeptiChek Supplemented Peptone ( x 2) Supplemented Peptone Trypticase Soy broth ( X 2) Trypticase Soy broth and Thiol broth Trypticase Soy broth and Brain Hearth Infusion broth Trypticase Soy broth and Columbia broth Trypticase Soy broth, Brucella broth, and Columbia broth Trypticase Soy broth and Brucella broth Fisher bottles Columbia broth only Columbia broth and Brain Heart Infusion broth Columbia broth and Thiol broth Columbia broth and Supplemented Peptone broth Columbia broth ( X 2) Brucella broth, Columbia broth, and Brain Heart Infusion broth Brucella broth and Thiol broth Brain Heart Infusion broth and Thioglycollate broth Thioglycollate broth only Thiol broth only Biphasic bottles

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12. Do you make recommendations as to the number and timing of blood culture specimens? - 1’74 yes If yes, specify:

62

No specific timing 15min intervals 30-min intervals I-hr intervals

no 2 setslday

3 setslday

4 setslday

3 8 14

18 21 62

2

3

40

6

I

13. Do you use a biphasic medium for routine bacteriologic culture? 29 53 191

Routinely (25 of these are Roche Septi-Chek) Special Request Never

14. Indicate the volume of broth contained in the culture bottle(s) and the amount of blood added. 6 h 1 113 7 20

20mL(3-5 mL) 25 mL (10 mL) 30 mL (3-5 mL) 40 mL (10 mL) 45 mL (5 mL)

- 41 15 14 31

50 mL (5 mL) 70 mL (5 mL) 70 mL (10 mL) lOOmL(lOmL)

15. Is the culture medium supplemented with sodium polyanethol sulfonate (SPS)? - 260 yes 175 If yes, what concentration is used? 0.025-0.03% 0.05-0.06% 43 7 no 2 Add SPS to the blood specimen during collection.

16. Are any additional enrichment substances added to the culture medium? - 27 yes If yes, what? 1 gelatin, Fildes 1 lsovitalex 2 PABA 1 Quadtone peptone, vitamin, amino acids 3 ~ 10% sucrose 1 Selected meat peptone, yeast extract, amino acids, vitamin K, hemin, gelatin 6 Vitamin K, hemin I Vitamin K, hemin. B, 2 Vitamin K, hemin, cysteine, gelatin 1 Vitamin K, hemin, cysteine, B, 2 Vitamin K, hemin, PABA 1 Vitamin K, hemin, yeast extract, animal tissue digest 1 xv 1 Yeast extract, starch 1 Yeast extract, meat peptone, tryptic casein digest, vitamin, amino acids

17. Is penicillinase added to blood cultures? - 32 yes ~ 243 no

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18. Do you use an antimicrobial removal resin device or culture bottle? - 153 yes If yes, when? upon special request 68 patient on antibiotics 80 126 no If no, what, if anything, is done when a patient is receiving antibiotics? 2 Extended incubation 3 PABA Penicillinase 3 Draw at trough of antibiotic 16 2 use Isolator 19. Are these bottles processed in a manner similar to the routine blood culture bottles? _ 172

yes

.--CL

no

25. How long are cultures routinely incubated before being reported as negative or no growth? No. of Laboratories Responding No. Days Incubated

Aerobic Cultures

Anaerobic Cultures

2 3 4 5 6 7 8 10 14 18

2 2 1 14 3 206 3 16 7 1

1 2 1 13 3 206 4 16 8 1

Resin Bottles

93 1 1 1

26. Do you incubate cultures longer than routine and if so, how long? No. of Laboratories Responding No. Days Incubated 7 9 10 14 21 28 42 56

Brucella Cultures

Suspected Endocarditis

2 27 138 79

6 I 2 48 41 16

Special Request 1

18 13 25 4

1

27. How often are cultures examined visually or radiometrically for growth? No. of Laboratories Responding Frequency 1/day 2lday 2 x /day for 2 days then 1 X /day 3 x /day for 3 days then 1 X /day 2-4xlday 112 days

Clinical Microbmlog; Newsletter 8: 16.1986

Aerobic Cultures

Anerobic Cultures

85 50 168 7 3

158 32 19 2 I

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28. In the absence of visual or radiometric evidence of growth, what other techniques are employed to detect bacterial growth . and when are they used? 8 Infrared, When daily Blind Subculture

.

Blind Gram Stain

8 5 4 13

22 10 11 27 4 2

35 23 50 63 34 17

24 hr 48 hr end of incubation once during incubation twice during incubation three times during incubation

Acridine Orange Stain

1

29. Blind subcultures: media employed included blood agar, chocolate agar, anaerobic blood agar, thioglycollate broth, and brain heart infusion broth (percent of respondents). Vented bottles Unvented bottles

~ 85% 13% ~ 32% 41% 26%

subcultured subcultured subcultured subcultured subcultured

aerobically (5- 10% CO,) aerobically and anaerobically aerobically anaerobically aerobically and anaerobically

30. What method is used to sample the bottles for subculture’? 209 2 1 52 3

Needle and syringe Bacteriological loop Swab Venting unit Transfer pipet

31. If growth is detected by any method in only one culture bottle, do you subculture the other bottles inoculated with the same specimen if they appear negative? 160

97

yes

no

33. Assume that you have a turbid bottle or a bottle with a high BACTEC growth index. The gram stain is negative and the routine subcultures are negative. What is your next procedure? 66 69

Reincubate or resubculture Subculture for:

36 15 8 7 3

Campylobacter Legionella Mycobacteria Mycoplasma Brucella

52

Subculture to: 32 Broth: thioglycollate, Thiol, new bottle, hypertonic media 20 Blood agar or chocolate agar with staph streak 107 Perform special stains: 71 Acridine orange Acid fast 18 17 Darkfield 1 Giemsa 32 Check patient’s white blood cell count

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34. Do you perform direct antimicrobial susceptibility tests on positive blood cultures (i.e., directly from the broth)? This question does not apply when using isolated colonies (as on Isolator plates or Septi-Check paddles). 186 yes (some laboratories employ both methods) Kirby-Bauera 64 Directly inoculate Mueller-Hinton plate with blood culture broth 28 Incubate several drops in Mueller-Hinton broth, Trypticase soy broth, or Brain Heart Infusion broth to 0.5 McFarland standard 16 Slow spin to sediment RBC, fast spin to sediment the organisms. Wash with saline. Adjust to 0.5 McFarland standard 12 Centrifuge. Resuspended pellet in Trypticase soy broth to 0.5 McFarland standard 10 Other MIC Methods 65 28 MicroScan 18 Vitek 5 Micromedia 5 Sensititre 4 Scepter 3 AutoScan 2 Abbott MS-2 MIC Inoculum preparation 65 24 Incubate several drops in Brain Heart Infusion broth Centrifuge at low speed to sediment RBC, Centrifuge at high speed to sediment 11 the organisms. Wash. Adjust inoculum to McFarland standard. 8 Centrifuge. Use pellet in saline, brain heart infusion broth. 12 Other 10 Not specified

35. Do you attempt rapid (same day) identification of bacteria from blood cultures (i.e., directly from the broth)? This question does not apply when using isolated colonies. 77

Yes, Methods for inoculum preparation were similar to those used for susceptibilie testing. Some laboratories employed more than one method of the organism. depending on the Gram-stain morphology

Methods employed include: Two-step centrifugation 15 Several drops of blood culture in Brain Heart Infusion broth, saline or tryptic soy broth. ~ 14 Direct inoculum 11 Direct use of pellet after centrifugation What identification system(s) do you use for rapid (same day) identification directly from the broth? (This does not include routine procedures.) (4); Gram-negative bacilli: API(55); Vitek (27); Micro-ID (12); Q uantum (5); Antigen Testing for Haemophilus Scepter (3); MicroScan (3). Gram-positive cocci in clumps: direct tube coagulase (68); Latex test (18); Vitek (15); Thermonuclease (7); Scepter (3); MicroScan (1). Gram-positive cocci in chains: Antigen testing (42); Bile esculin (29); Vitek (18); API (3); Scepter (1); MicroScan (1). Gram-positive bacilli: Vitek (10); Minitek (2). Gram-negative cocci: antigen testing (12); NH-ID (10); RIM (9); Minitek (3); Vitek (3); API (2); DuPont (1). Anaerobes: ANA-ID (18); API (14); Direct glc (8); Scepter (I). 61

36. Do you repeat the identification after the organism is isolated? ~

76

Yes

-

16

No

38

Only if questionable

Survey questions not addressed above will be discussed in the next issue of the Newsletter.

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