媽媽，我的耳朵好痛 － 中耳炎

前言：為什麼中耳炎總事發生在小朋友身上呢？

Urinary Tract Infections【泌尿道感染】

又到了 Infection 中第二大科的章節 － Urinary Tract Infections (UTI)

✿ General Principles

☞ Definitions
－ UTI is a bacterial infection that  affects parts of the urinary tract.

☞ Classification

★Anatomic [解剖學] － 細菌是尿道口往上進入逆尿系統，故我們也由下往上看!!

► lower: urethritis, prostatitis, cystitis (superficial infection of  bladder)

    

▪ Urethritis [尿道炎]: often sexually-transmitted

▪ Cystitis [膀胱炎]: traditional UTI
▪ Prostatitis [前列腺炎]: in men (廢話 XD)

► upper; pyelonephritis [腎盂腎炎]

★Clinical

uncomplicated [無併發症]: in healthy women, w/o (without) underlying disease
complicated [合併併發症]: in women, any UTI men or pregnant women with underlying disease

✿ Clinical manifestations

▲Cystitis: dysuria [解尿疼痛], urgency [急尿], frequency [頻尿], burning sensation [解尿灼熱感], hematuria [血尿], 改變尿液的顏色和氣味, suprapubic [恥骨部]疼痛; 一般不會發燒
▲Urethritis: 除了有尿道分泌物外，其餘症狀與 cystitis 一樣. cystitis 和 urethritis 都應排除 viginitis [陰道炎]的症狀
▲Prostatitis:
chronic: 除了有排尿困難 (hesitancy [解尿遲疑], weak stream [尿流慢])外，其餘其餘症狀與 cystitis 一樣
acute: perineal [會陰部]疼痛, fever, 有 tenderness [壓痛]的 prostate [攝護腺]

▲Pyelonephritis: fever, chills [畏寒], flank [腹側] or back pain, 噁心, 嘔吐, 腹瀉
▲Renal abscess

✿ Diagnostic studies

► Urinalysis [尿液檢查]: pyuria [膿尿] + bacteriuria [菌尿症] ± hematuria ± nitrites
   
我們總是在書上看到 UTI 會有以上這4種現象，但卻沒告訴我們其臨床意義，那就趁現在好好了解一下吧~

♣ Urine Routine;Urinalysis [尿液常規]

▪ WBC [白血球]: 尿中的白血球通常以嗜中性球為主，淋巴球次之，而是酸性性最少。

→ 輔助診斷各種腎臟疾病

→ 尿液中出現過多的嗜中性球 (高倍視野下超過5顆)：又稱為 pyuria, 表示泌尿道出現感染或發炎。

▪ Bacteria [細菌]: 正常情形下，尿液中不該出現細菌，當尿中發現有細菌時，表示有 UTI 可能，但須排除不正確收集尿液方式所造成的外陰部細菌汙染。

→ 輔助診斷 UTI

→ 尿液中發現有細菌: 表示有 bacteriuria

▪ Occult Blood [潛血]: 當有大量血尿、血紅素尿或肌紅蛋白尿時，尿液通常呈現紅色或棕色，此時可用尿液潛血試驗來鑑別其他造成紅棕色尿液的原因。

→ 篩檢 hematuria [血尿]、hemoglobinuria [血紅素尿]、myoglobinuria [肌紅蛋白]

→ hematuria: 指尿中出現紅血球

▪ RBC [紅血球]: 正常情況下，尿中 RBC 在高倍視野下不超過2顆。

▪ Nitrite [亞硝酸鹽]: 許多細菌，泌尿道感染時，例如 Escherichia coli [大腸桿菌], Klebsiella [克雷白氏菌], Enterobacter [腸桿菌], Proteus [變形桿菌], Staphylococcus [葡萄球菌], Pseudomonasa [假單孢菌]可將尿液中的 nitrate [硝酸鹽]代謝成 nitrite [亞硝酸鹽], 當尿中細菌大於 10^5/mL 時, nitrite 大量產生便會呈現陽性反應。

→ 診斷 UTI 的間接方法

→ Nitrite (+): UTI

→ Enterococcus, Neisseria gonorrhea 及 Mycobacterium tuberculosis 不會將 nitrate 代謝成 nitrite.

▪ Leukocyte Esterase [白血球酯酶]: 尿液中若存在有大量嗜中性球即暗示有 UTI, 嗜中性球會釋放出 esterase, 故尿中 leukocyte esterase 增加為診斷 UTI 的間接方法。因尿液中嗜中性球並不穩定而容易分解，當顯微鏡檢尿液沉渣未發現大量白血球，而病患又有 UTI症狀時, leukocyte esterase 便可當作輔助診斷的工具。

→ 診斷 UTI 的間接方法

→ Leukocyte Esterase (+): 懷疑有 pyuria

► Urine Cx : 當有 symptoms 時才需做 cx (culture).

→ 從 clean-catch midstream [清潔排出之中段尿液] or straight-cath specimen [導尿管檢體]

▪ Significant bacterial counts:

   typically ≧10^5 CFU/mL in women, ≧10^3 CFU/mL in men or cathrterized [導尿] Pts.

▪ Pyuria & (-) UCx = sterile pyuria [無菌性膿尿症]

→ urethritis, nephritis [腎炎], renal tuberculosis [腎結核感染], foreign body [異物]

► Blood culture: 有 febrile Pts 才需要; 考慮有 complicated UTIs

✿ Microbiology

▪ Uncomplicated UTI: E.oli (80%), Proteus, Klebsiella, S. saprophyticus

→ 在健康的人和非懷孕婦女: lactobacilli, enterococci, Group B strep and coag-neg staph (except S. saprophyticus) 通常是汙染物

▪ Complicated UTI: E.coli (30%), enterococci (20%), PsA (20%), S. epi (15%), other GNR

▪ Catheter-associated UTI: yeast (30%), E.Coli, other GNR, enterococci, S. epi

▪ Urethritis: Chlamydia trachomatis, Neisseria gonorrhoeae, Ureaplasma urealyticum, Trichomonas vaginalis, Mycoplasma genitalium, HSV

✿ Treatment

Referance：

1. The Washington Manual of Medical Therapeutics 34th Edition, Pancreatobiliary Disorders．Gallstone Disease
2. The Massachuetts General Hospital Handbook of Internal Medicine 5th Edition, Urinary Tract Infections

Pneumonia 【肺炎】

說到 Infectious Diseases，就不得不提到這個經典中的經典 － Pneumonia【PNA】

肺炎的定義：簡單來說就是肺部組織受到感染。

那是如何進到我們肺部呢？我們就要把肺炎細分為以下4大類：

< Microbiology of Pneumonia >

1. Community-acquired pneumonia (CAP)

• S. pneumonia
• Mycoplasma, Chlamydia, viral (esp. in young & healthy)
• H. influenzae, M. catarrhalis (esp. in COPD)
• Legionella (esp. in elder, smoker, ↓ immunity, TNF inhibitors)
• Klebsiella & other GNR (esp. in alcoholics & aspirators)
• S. aureus (esp. postiviral infection)

2. Hospital-acquired pneumonia or Health care-associated pneumonia (HAP/HCAP)

• GNR including Pseudomonas, Klebsiella, E. coli, Enterobacter, Serratia, Acinetobacter
• S. aureus (including MRSA)
• Acid suppression may ↑ risk of acquiring PNA － 說穿了就是 PPI, H2 blocker....

3. Aspiration pneumonia

• Chemical pneumonia due to aspiration of gastric contents
• Bacterial pneumonia ≧24-72 hrs later, due to aspiration of oropharyngeal [口咽] microbes

            - outPt: typical oral oral flora (strep [鏈球菌], S. aureus, anaerobes [厭氧菌])

            - inPt or chronically ill: GNR and S. aureus

4. Immunosuppressed pneumonia → 『非本章重點，可先不記』

• Above + PCP, fungi, Nocardoa, non-TB mycobacteria, CMV, HSV

< Clinical manifestations >

• "Typical [典型]": acute onset of fever, cough帶濃痰, dyspnea [呼吸困難], Chest X-ray (CXR) 呈現 consolidation [實質化]
• "Atypical [非典型]": dry cough 或陣發性刺激性咳嗽, 肺外症狀居多 (nausea and/or vomiting, diarrhea [腹瀉], myalgias [肌肉痠痛], sore throat [喉嚨痛]), 在 CXR 會呈現 patchy interstitial pattern [斑片狀間質性型態], 一般不引起肺部實變及胸腔積液
• 病徵、症狀和影像學檢查都無法可靠地區分 "typical" (S. pneumo, H. flu) 和 "atypical" (Mycoplasma, Chlamydia, Legionella, viral) 兩者差異
• Legionella 會使 ↑ aminotransferases & ↓ Na (50-70% 呈現低鈉血症, 尤其 < 130 mmol/L)

Treatment

1. Outpatient

• No recent abx; macrolide or doxycycline
• Recent abx or comorbidities [共病症] (eg, cardiopulm, hepatorenal, DM, EtOH); respiratory FQ or (macrolide + [high-dose amox ± clav or 2nd-gen ceph.]) 

2. Community-acquired, inpatient

• (3rd-gen ceph. + macrolide) or respiratory FQ
• MRSA coverage, if necrotizing [壞死性] or with empyema [積膿] (罕見)

3. Community-acquired, inpatient, ICU

• (3rd-gen ceph. or amp-sulbactam) + (macrolide or FQ) (假設 no risk for Pseudomonas)

4. Hosp-acquired & risk for MDR pathogens

• (Antipseudomonal PCN or ceph. or carbapenem) + (FQ or [gentamicin + azithromycin]) + MRSA coverage

5. Immunosppressed

• As Above ± TMP-SMX ± steroids to cover PCP

6. Aspiration

• (3rd-gen ceph. or FQ) ± (clindamycin or metronidazole)

Empirical Antibiotic Treatment

Outpatients

Previously healthy and no antibiotics in past 3 months l   A macrolide (clarithromycin [500 mg PO bid] or azithromycin [500 mg PO once, then 250 mg qd]) or l   Doxycycline (100 mg PO bid)

Comorbidities or antibiotics in past 3 months: select an alternative from a different class l   A respiratory fluoroquinolone (moxifloxacin [400 mg PO qd], gemifloxacin [320 mg PO qd], levofloxacin [750 mg PO qd]) or l   A β-lactam (preferred: high-dose amoxicillin [1 g tid] or amoxicillin/clavulanate [2 g bid]; alternatives: ceftriaxone [1–2 g IV qd], cefpodoxime [200 mg PO bid], cefuroxime [500 mg PO bid]) plus a macrolidea

In regions with a high rate of“high-level”pneumococcal macrolide resistance,b consider alternatives listed above for patients with comorbidities.

Inpatients, Non-ICU

l   A respiratory fluoroquinolone (e.g., moxifloxacin [400 mg PO or IV qd] or levofloxacin [750 mg PO or IV qd]) l   A β-lactamc (e.g., ceftriaxone [1–2 g IV qd], ampicillin [1–2 g IV q4–6h], cefotaxime [1–2 g IV q8h], ertapenem [1 g IV qd]) plus a macrolided (e.g., oral clarithromycin or azithromycin [as listed above] or IV azithromycin [1 g once, then 500 mg qd])

Inpatients, ICU

l   A β-lactame (e.g., ceftriaxone [2 g IV qd], ampicillin-sulbactam [2 g IV q8h], or cefotaxime [1–2 g IV q8h]) plus either azithromycin or a fluoroquinolone (as listed above for inpatients, non-ICU)

Special Concerns

If Pseudomonas is a consideration: l   An antipseudomonal β-lactam (e.g., piperacillin/tazobactam [4.5 g IV q6h], cefepime [1–2 g IV q12h], imipenem [500 mg IV q6h], meropenem [1 g IVq8h]) plus either ciprofloxacin (400 mg IV q12h) or levofloxacin (750 mg IV qd) l   The above β-lactams plus an aminoglycoside (amikacin [15 mg/kg qd] or tobramycin [1.7 mg/kg qd]) plus azithromycin l   The above β-lactamsf plus an aminoglycoside plus an antipneumococcal fluoroquinolone If CA-MRSA is a consideration: l   Add linezolid (600 mg IV q12h) or vancomycin (15 mg/kg q12h initially, with adjusted doses)

註： aDoxycycline (100 mg PO bid) is an alternative to the macrolide. bMICs of >16 μg/mL in 25% of isolates. cA respiratory fluoroquinolone should be used for penicillin-allergic patients. dDoxycycline (100 mg IV q12h) is an alternative to the macrolide. eFor penicillin-allergic patients, use a respiratory fluoroquinolone and aztreonam (2 g IV q8h). fFor penicillin-allergic patients, substitute aztreonam. Abbreviations: CA-MRSA, community-acquired methicillin-resistant Staphylococcus aureus; ICU, intensive care unit.