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2017年1月5日 星期四

[醫如往常] Senior Clerkship Day 102: Lab Medicine: 細菌室

細菌室 薛P
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CSF 絕對不能冰,一小時送到檢醫部
  • Pneumococcus
  • Meningococcus
  • HiB

  • E coli
  • Listeria
  • KP
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CSF半小時送給細菌室 馬上接種
Gram stain危急值半小時內醫師要確認
沒確認打電話叫臨床看病歷系統
CAP要求99.9%
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Urine要冰,也是一小時送到
Loop 0.001ml
>10 0000 CFU
不能驗gonococcus(因為冰了會死掉),要用discharge culture, chocolate medium

一般Urine不做厭氧菌,做了也是汙染菌(unless suprapubic aspiration)
Vaginal discharge也不做厭氧菌
Stool做厭氧則是為了Clostridium difficile
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NTUH每天220culture,一天40個陽性,一半白天,一半晚上
60%來台大前就用過抗生素,要用resin血瓶

左右手各一套2-4瓶,陰性菌,陽性菌,黴菌,TB

Blood culture 也是一小時
Time to positive TTP
KP TTP七小時內的死亡率是TTP七小時以上的兩倍

Gram stain 30分鐘確認
Error 3%

導管菌血症TTP兩小時positive是導管感染

正常80%一天長, 95%兩天長
  • 細菌五天發no growth
  • TB 42天發no growth (最快7天長出來)
  • 黴菌28天發no growth (fungus都是需氧)
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Sputum要冰
所以養不出pneumococcus, HiB
找到yeast通常沒有意義,不會發報告
sputum不做厭氧菌,因為口腔一堆厭氧菌
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The wenstein–Jensen medium, more commonly known as LJ medium, is a growth medium[1] specially used for culture of Mycobacterium species, notably Mycobacterium tuberculosis.
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Q score
Documentation: 
Bartlett developed the Q score to grade the quality of a specimen sent for culture based on the Gram stain appearance. This can help determine if the specimen is good, fair or poor.
Specimen selection: A specimen from the lower respiratory tract or a superficial wound.
Gram stain examination: 10 to 20 low power (10x objective) microscopic fields
Parameters:
(1) average number of neutrophils present per low power field
(2) average number of squamous cells present per low power field
(3) presence of ciliated respiratory epithelial cells if a sputum specimen
(4) leukopenia due to disease or therapy
Parameter
Finding
Points
average number of neutrophils
0 (none)
0

1 to 9 (few)
+1

10 - 24 (moderate numbers)
+2

>= 25 (many, numerous)
+3
average number of squamous cells
0 (none)
0

1 to 9 (few)
-1

10 - 24 (moderate numbers)
-2

>= 25 (many, numerous)
-3
composite Q score =
= (points for average number of neutrophils) + (points for average number of squamous cells)
Interpretation:
• minimum score: -3
• maximum score: +3
• The higher the score the better the specimen.
A specimen with a composite score >= +1 should be cultured.
• A sputum specimen from a leukopenic patient with ciliated respiratory epithelial cells should be cultured.
• A composite Q score that is 0 or negative is probably a superficial sample that may not be a reliable specimen and so is usually not cultured.


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培養結果的判讀沒有所謂的黃金標準,常用的判別方式大致依病人的臨床狀況、分離菌種及陽性培養套數做判斷[1,3,6,7,9]。常見陽性的指標如下:1.病人具有敗血症症狀如發燒、體溫過低、白血球過多或過少、低血壓。2.分離出的菌種不像污染菌,如Staphylococcus aureus、Candida spp.、Streptococcus pneumoniae、Escherichia coli、其他腸內菌科及Pseudomonas aeruginosa 90%以上為致病菌;Strep. agalactiae、Strep. pyogenes、Listeria monocytogenes、Nesseria meningitidis、Nesseria gonorrhoeae、Haemophilus influenzae、Bacteroides fragilis group、Cryptococcus neoformans則皆為致病菌幾乎不可能為汙染菌[6]。3.由不同抽血部位抽取的檢體,同時分離出相同的病 原菌。但如為白血病患者則上述臨床症狀則可能不適用。

CoNS、Corynebacterium spp.、Propionibacterium acnes及碳疽桿菌之外的Bacillus spp.、Micrococcus spp.、viridans streptococci及Clostridium perfringens[6]為污染的可能性較高,其中又以C. spp.、P.acnes、M. spp.及碳疽桿菌之外的Bacillus spp.的致病機率最低。但上述各菌種為真正致病菌的百分比,在每個研究的結論並不一致,所以醫師無法僅以菌種名稱決定分離菌株的臨床意義。
只以分離套數來區分CoNS是否為污染菌,結果並不正確,依據文獻結果:兩套培養皆分離CoNS和兩套培養中只有1套分離的污染可能性,分別為31%及87%[4];12-31%的污染個案為多套分離,而12-35%的真正感染菌只有從單套培養分離[3,4,7]。故只能說愈多套分離其為污染菌的可能性愈小。而若只有抽單套培養又培養陽性時,其污染的可能性則為67-89%,判讀其臨床意義的困難度更高,故不建議只送單套血液培養[4,7]。另外以分子生物方法,分析同一病人由導管處及週邊血管同時分離的S. epidermidis時,發現4/14為不同型;另一研究則發現插管後14天,55%至少兩套分離的CoNS為不同型,可能為污染或多重菌株感染[7],故僅以分離套數來界定分離菌株的臨床意義確實有其缺點存在。

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AST; antimicrobial susceptibility test: 一種抗生素Etest一隻$150,健保只給付220
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Bruker Maldi-Tof MS
一台800萬,做一次的成本2
但沒有買機器的話,做一次200

美國沒有的Burkholderia pseudomallei
Vibrio vulnificus
Penicillin marafi (AIDS常見)
質譜儀容易跑錯
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黃醫師
FUO
murmur, cordae tenden rupture
IE,

注意水質,legionella

Campylobacter 兩個彎
Helicobacter 多個彎

Candin不能cryptococcus
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Catheter infection
TTP 早兩小時
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PJP PCR
成本600
1000
長庚4500
Dyspnea spo2 90%
CXR 不明顯 clear

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TSI Mueller-Hinton medium
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Urine 看到candida很正常
看到CryptococcusDissemination

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