HYPOXIA KILLSDr KY WaiDr G Au

CASE 1�M/48� Good past health� Admitted for fever and altered mental function� Feeling unwell with generalised bone pain, headache and URTI symptoms for few days prior to admission� Detail history otherwise unknown� TOCC –ve

PHYSICAL EXAMINATION� BP 111/68, P 133/min� SaO2 96% (100% O2 mask)� CVS: NAD� Chest: clear� Abdomen: NAD� CNS: E4V1M1, jerks normal, plantars equivocal

PROGRESS�WBC 1.7� Hb 16.4� Plt 43� Cr 170� AST/ ALT 95/73, bilirubin normal� CPK 254� CXR clear

PROGRESS� Electively intubated for airway protection� Septic workup done� Empirically started on meningitic dose of rocephin and acyclovir� CT brain: unremarkable� LP performed� Opening pressure 11� Transfer to ICU for further care

UPON ICU ADMISSION� GCS 3/15� Temp 38.1 C� BP 113/69, P 130/min, sinus tachycardia� CVS/ Chest/ abdomen examination NAD� Echo: good biventricular function� USG abdomen: no SOL in liver, CBD normal, contracted GB, both kidneys are normal in size (~11 cm)

PROGRESS� Blood test on D1:� WBC 6.9, Hb 10.8, Plt 95� Cr 222, K 3.3, Na 145� Bili 46, ALP 108, AST/ ALT 4131/ 2030� INR 2.5� ABG: pH 7.165, pCO2 3.65, pO2 12.2, BE -19, HCO3 9.9

LP RESULT�WBC 1� TP 0.63, glucose 3.5 (blood 5.8)� Gram stain and C/ST negative� AFB smear and PCR negative� Fungal C/ST –ve� HSV PCR –ve� Cytology -ve

PROGRESS� Develop septic shock, started on inotropes and hydrocortisone� Acute renal failure started on CVVH on D2� Progressive worsening of LFT� Blood C/ST (D4): gram negative bacilli� Meronam started� Phone report from microbiologist on D5� Bacteroides species� Flagyl added� Blood C/ST: bacteroides fragilis group

PROGRESS7/6 8/6 9/6 10/6 11/6 12/6 13/6 14/6 15/6 16/6

WBC 6.9 9.4 9.1 9.8 10.3 9.4 6.9 9.3 17.3 19.6

Hb 10.8 10.0 9.6 9.8 9.0 8.9 9.6 9.5 10.9 9.8

Plt 95 43 40 44 23 18 27 39 47 39

Bili 46 41 103 134 189 239 325 387 515 446

ALP 108 72 106 144 143 152 134 123 141 180

AST 4131 7802 18135 11764 4267 1474 554 300 244 272

ALT 2030 4873 10758 9723 6797 4919 3211 2427 1664 907

INR 2.5 3.4 >8.0 3.1 4.2 4.4 3.1 5.4 5.2 7.1

Cr 222 428 406 374 353 361 340 329 324 329Ammonia 35 125 145

Ab Roc + Acy

Roc + Acy

Roc + Acy

Roc + Acy

Mero+ Acy

Mero+ Flagyl+ Acy

Mero+ Flagyl

Levo+Flagyl

Levo+Flagyl

Levo+Flagyl

PROGRESS� CT brain: unremarkable� CT abdomen and pelvis: unremarkable� Anti HAV IgM -ve� HbsAg -ve� Anti HCV Ab –ve� Anti HEV Ab-ve� Anti HIV Ab –ve� Hantavirus Ab -ve� Transfusion with Plt conc/ FFP + vit K1 given� Condition continue to deteriorate with progressive liver failure� Finally succumb on D10

CLINICAL POSTMORTUM�Massive hepatic necrosis� Etiology cannot be determined based on the pathologic findings because of extensive necrosis

CASE 2� F/85� Past medical history� DM� HT� beta thalassemia trait� Dementia, MMSE 9/30� Atypical chest pain with + positive treadmill, normal coro 2000

� Renal impairment , Cr ~200

� Admitted to orthopaedic ward for slip and fall� X-ray: fracture L TOF

CXR ON ADMISSION

BLOOD TEST ON ADMISSION�WBC 17.4 (Neut 15.5, Lymphocyte 0.7, Monocyte 1.1, eosinophil 0.1)� Hb 6.9, MCV 71.2, plt 242� INR 1.09� Urea 20.1 Cr 266, Na/K 140/4.3� LFT normal, A/G 35/37

PROGRESS� 3 units of packed cells transfused, post transfusion Hb 9.7� Remained well until day 4� Found patient vomiting and become unconscious� Bp 60/40, P 100/min� SpO2 94% on 100% O2� Dopamine started� Intubation by anaesthetist, found food debris in month� CT brain unremarkable� Transfer to ICU for further care

UPON ICU ADMISSION� GCS 4/15� BP 74/26, P 80/min� SaO2 93% (FiO2 0.5)� Temp 35 C� Dehydrated with cold peripheries� CVS unremarkable� Chest: bilateral crepitation� Abdomen: distended, BS +ve

CXR

AXR

BLOOD TEST ON ICU ADMISSION� pH 6.94, pCO2 7.6, pO2 24.4, HCO3 12.1, BE -20.5, SaO2 98.3� Na/K 150/5.0� Urea/Cr 29.3/399, CK 129, LDH 1452� Trop I <0.02�WBC 29.5, Hb 12, MCV 77.9, plt 307� INR 2.1� CRP 139� ECG: AF, HR ~100/min

PROGRESS IN ICU� Started on sulperazon 1g q12h iv� BP remained lowish despite 3 inotropic agents at high dose� Acute on chronic renal failure with CVVH started

PROGRESS IN ICU� ABG: pH 7.083, pCO2 7.46, pO2 18.7, HCO3 16.7 (10 hours after CVVH)� Hypoglycaemia and put on dextrose drip� Vasopressin added� Surgeon consulted for ?bowel ischaemia� In view of poor condition, will not benefit from operation and CT abdomen will not be beneficial, suggest continue support care

� Died ~25 hours after ICU admission� Referred coroner - waived� Blood C/ST (3 days after death of patient): Clostridium perfringens� Sputum C/ST: coliform bacilli� CSU: microscopy NAD, C/ST: enterococcus species

CASE 3�M/30� Chronic smoker and drinker� Good past health

� Admitted for fever and repeated vomiting for 4 days� Associated with epigastric pain� Sore throat and headache+� no cough/ sputum� No diarrhoea/ PR bleeding� No urinary symptoms� Contact/ travel history –ve� Physical examination unremarkable except temp 37.5 C and mild tenderness over epigastrium

INVESTIGATION ON ADMISSION� CXR: clear, no gas under diaphragm� AXR: NAD�WBC 11.8� Clotting profile normal� LRFT normal� Started on empirical augmentin

DAY 2 � Sudden increase in epigastric pain� Shock with BP 87/32, Pulse 120/min� Temp 39.5C, SaO2 91% (100% mask)� Cr 107->243� Plt 254 -> 87� INR 1.52 � WBC 13� Amylase normal� Bedside USG abdomen: normal � Urgent CT abdomen + pelvis: unremarkable� Empirical step up to meronam 1g q12h and septic workup repeated after seen by microbiologist� Transfer to ICU for monitoring

UPON ICU ADMISSION� T 37C� SaO2 93% on 100 % non-rebreathing mask� BP103/56, P 103/min, on dopamine 4:1 8ml/hr� Blood result� pH 7.39, pCO2 5.1, pO2 9.8, HCO3 23, BE -2.0 (50% O2 mask)

� Cr 187� LFT normal� WBC 14, Hb 10.8, Plt 47, INR 1.2� Continued on meronem

PROGRESS –D3� Persistent high fever� Blood C/ST showed gram negative bacilli� On and off requiring BiPAP to maintain saturation

CXR

PROGRESS - DAY 4-6� Persistent high swinging fever� No abdominal pain � Blood C/ST: anaerobic gram negative bacilli� > metronidazole 500 mg q8h iv added� Anti- HIV Ab –ve�Widal test –ve� Rickettsia Ab –ve�Weil – felix test –ve� USG abdomen unremarkable� Gradually weaned off inotropes

PROGRESS - D7� Afebrile� 4L/min O2� Blood C/ST: Fusobacterium necrophorum� > ? Lemierre’s Syndrome� Echo: no valvular lesion, good LVSF, bilateral internal jugular vein patent, no thrombi seen� RFT normalised� Discharged to general ward on D9� Completed antibiotic, discharged home on D14

SUMMARY� 3 cases of bloodstream infection� Case 1: Bacteroides fragilis� Case 2: Clostridium perfringens� Case 3: Fusobacterium necrophorum

�What are they in common?

ANAEROBES

INTRODUCTION� Anaerobic bacteria are defined as bacteria that grow in the absence of oxygen and fail to show surface growth in 10% carbon dioxide in air� It could possibly react negatively and may even die if oxygen is present� Anaerobes is an uncommon yet important cause of bloodstream infection� Account for 1-17% of positive cultures

ANAEROBIC ISOLATES FROM BLOOD CULTURE IN KWH

2008 2009 2010 2011Total no of organism isolated from blood C/ST

952 834 766 763

Total no of anaerobes isolated from blood C/ST

15 32 22 31

% 1.6% 3.8% 2.9% 4.1%

OUT OF SIGHT OUT OF MIND1. The lack of widely available

diagnostic methods other than Gram stain and culture

2. Fastidious growth requirements that often limit recovery

3. Ubiquity on mucocutaneoussurfaces that hampers obtaining meaningful cultures

4. Often derived from normal flora, which sample contamination can confuse

BACTERIA O2 TOLERANCE� Obligate� Grow in </= 0.4% O2� e.g., C. haemolyticum, C. novyi type B, oral treponemes

� Facultative� Grow in < 2.5-3% O2� e.g., B. fragilis group, C. perfringens , Prevotella, Porphyromonas,

Fusobacterium

� Aerotolerant� Grow in >3% O2� e.g., C. tertium, C. histolyticum, C. carnis

� Most clinically important anaerobes (Bacteroides fragilis, Prevotellamelaninogenica [formerly classified as Bacteroides melaninogenicus], and Fusobacterium nucleatum) are moderate anaerobes

CLASSIFICATION� Spore forming� Gram positive rod� Clostridium

� Non spore – forming� Gram positive rod

� Propionibacterium� Bifidobacterium� Lactobacillus� Eubacterium� Actinomyces

� Gram negative rod� Bacteroides� Campylobacter� Fusobacterium

� Gram positive cocci� Peptococcus� Peptostreptococcus

� Gram negative cocci� Veillonella

BACTERIA IN LIQUID CULTURE

Obligate aerobe

Obligate anaerobe

Facultative bacteria

Microaerophiles Aerotelerantbacteria

RISK FACTOR� Exposure of sterile body sites to large innoculum of indigenous mucous membrane flora� Poor blood supply and tissue necrosis� Trauma� Foreign body� Malignancy� Surgery� Colitis� Vascular disease

� Diabetes mellitus� Splenectomy� Immunocompromise� Collagen vascular disease� Previous infection with aerobic or facultative organisms

CLUES TO ANAEROBIC INFECTION

1. Infections in continuity to mucosal surfaces

2. Infections with tissue necrosis and abscess formation

3. Putrid odor4. Gas in tissues5. Polymicrobial flora6. Failure to grow in the lab

SOURCES OF ANAEROBES� Environment� soil, marshes, lake and river sediments, ocean, sewage, food

and animals

� Endogenous flora� oral cavity (gingival crevice, tonsillar crypts)

� gastrointestinal tract (exp. colon)

� genitourinary tract� skin

BACTERIAL FLORA OF THE BODY

Site Total Bacteria Ratio(per/ml or gm) Anaerobes:Aerobes

Upper AirwayNasal Washings 103-104 3-5:1Saliva 108-109 1:1Tooth Surface 1010-1011 1:1Gingival Crevice 1011-1012 1000:1

Gastrointestinal TractStomach 102-105 1:1Small Bowel 102-104 1:1Ileum 104-107 1:1Colon 1011-1012 1000:1

Female Genital TractEndocervix 108-109 3-5:1Vagina 108-109 3-5:1

DIAGNOSTIC MICROBIOLOGY� Collection of specimens� Free of contamination since indigenous anaerobes are often present on the surfaces of skin and mucous membranes in large numbers

Expel all air bubble

SPECIMEN TRANSPORT� Prompt specimen delivery with oxygen-free environment� Culture within 2-3 hrs

CULTURE MEDIA� Inoculate specimens on to fresh enriched blood agar medium ( containing Vit K1 and hemin)� Selective medium can be used� Brucella or CDC BA, LKV, bile-esculin (BBE), PEA, and thioglycollate broth (THIO); PRAS media

� Increase the recovery rate� Shorten time to identify organism� Place plates in anaerobic jar/ chamber/glove box� Incubate 48 hrs or longer for exam� Check for new growth after 7 days� Other rapid tests, such as direct fluorescent microscopy, gas liquid chromatography, cellular fatty acid analysis

MEDIA FOR ISOLATION OF ANAEROBES

Anaerobic

blood agar

Columbia, Schaedler, CDC, Brucella, brain heart infusion, w/5% Sheep, YE, Vitamin K1, hemin

Nonselective (enriched)

Bacteroides

Bile Esculin

TSA, ferric ammonium citrate, hemin, bile salts, gentamicin

selective & differential for B. fragilis group

Laked blood kanamycinvancomycin

Brucella base with 5% laked blood, kanamycin & vancomycin

selective for Bacteroides and some Prevotella

Phenylethylalcohol

nutrient agar, 5% blood, PEA inhibits enteric GNR and swarming of some clostridia

Egg-yolk agar egg yolk base lipase & lecithinaseproduction

Chopped meat/ thioglycollate

meat particles/casein, soy, glucose, agar, vitamin K1, hemin

nonselective, enrichment broths

VITEK II

SENSITIVITY TEST

• Routine susceptibility testing is time-consuming and often unnecessary

• Limited to serious infection, isolation from blood, CSF, bone and pure culture

• National Committee for Clinical Laboratory Standards (NCCLS)

• agar dilution testing, microbrothand macrobroth dilution

ANTIBIOTIC SELECTION� Empirical treatment most of the time� ST rarely performed unless resistance suspected� Agents remain active against most anaerobes� Metronidazole� Carbapenem� Beta-lactam/ Beta-lactamase inhibitor� Other agents can be considered� Clindamycin, Moxifloxacin, Vancomycin, Tetracycline etc

BACTEROIDES FRAGILIS

BACTEROIDES FRAGILIS�Obligate anaerobic Gram negative bacillus�accounting for 41% to 78% of the Bateroidaceae�predominant components of the bacterial florae of GI tract�predominate in intra-abdominal infections and infections that originate from those florae, egperirectal abscess, decubitus ulcer�Enterotoxigenic B fragilis (ETBF) is also a potential cause of diarrhoea

CLINICAL PRESENTATIONS� CNS� Brain abscess, subdural empyema, epidural abscess and meningitis

� Head & Neck� Periodontal disease, gingivitis, otitis media, sinusitis, tonsillitis, thyroiditis, neck abscess

� Pleuropulmonary� Lung abscess, empyema

� Intra-abdominal� Secondary peritonitis, intraabdominal abscess, cholecystitis, diverticulitis etc

� Female genital tract� Vaginosis, endometritis, salpingitis, adnexalabscess

� Skin & soft tissue� Cellulitis, wound infection, gas gangrene

TREATMENT• The bacteria have inherent high-level resistance to penicillin

• In general susceptible to metronidazole, betalactam/ beta-lactamase inhibitor, carbapenem, tigecycleine

• Clindamycin is no longer recommended as the first line agent for B. fragilis due to the emerging high level resistance ( >30% in some reports)

Clostridium perfringens

MICROBIOLOGY OF CLOSTRIDIUM

� Gram positive� Spore-forming� Rod-shaped� Obligate anaerobes� C. perfringens� gas gangrene; food poisoning

� C. tetani� tetanus

� C. botulinum� botulism

� C. difficile� pseudomembranous colitis

C. perfringensPhysiology and Structure

Large gram-positive bacilli.

Spores are rarely observed.

Non-motile; capsulated.

Hemolytic and metabolically active.

Subdivided into 5 types based on the four major lethal toxins they produce. Type A causes most of the human infections.

CLOSTRIDIUM PERFRINGENS� Soft tissue infection� Portal of entry: trauma or intestinal tract.� Usually caused by mixed infection including toxigenicclostridia, proteolytic clostridia & various cocci & gram-negative organisms.� Requires damaged & dead tissue & anaerobic conditions� Fermentation of muscle carbohydrates results in the formation of gas & further destruction of tissue.� 3 types of infections with increasing severity:� Cellulitis: gas formation in the soft tissue.� Fasciitis or suppurative myositis: accumulation of gas in

the muscle planes.� Myonecrosis or gas gangrene: a life-threatening disease

Gas Gangrene

62

TREATMENT AND PREVENTION� Immediate cleansing of dirty wounds, deep wounds, decubitus ulcers, compound fractures, & infected incisions� Debridement of disease tissue� Large doses of cephalosporin or penicillin� Hyperbaric oxygen therapy � No vaccines available

63

CLOSTRIDIUM PERFRINGENS� Food poisoning� The enterotoxin causes marked hypersecretion in jejunum & ileum.

� Characterized by high optimum growth temp, around 43C-45C, unable to grow at temp <12C

� Doubles its number as fast as every 7.2 mins� Symptoms: Intense abdominal pain and acute diarrhea, usually without vomiting or fever

� Onset time: 10-12 hrs, recovery: 24-48 hrs� Spores can withstand cooking temperatures, toxin inactivated at 74C

� Marine sediment at the base of sewage outfalls was found to have higher amounts of C. perfringens

CLOSTRIDIAL FOOD POISONING

Food held too longat room temperature; cools slowly; spores germinate

(Meat or poultry)Spores

Bacteria sporulatein the small intestine; release enterotoxin

昨日仍有南亞裔人士在坑渠附近的梧桐河捕魚 2012-01-31Fish guts collected

from sewage outfalls were found to store higher amounts of C. perfringens

FOOD POISONING

DIAGNOSIS MANAGEMENT OF CLOSTRIDIAL FOOD POISONING� Usually recognized by multiple cases of diarrhea6-18 hours after ingestion of food� Culture of the patient is not helpful� Treatment is supportive only (resolves spontaneously); no antibiotics� Identify the food vehicle, (culture), and correct preparation problem

CLOSTRIDIAL BACTERIEMIA� Clinical Features of Clostridial Bacteriemia: A review from a rural areaCID 2001:33: 349-353� Clinical features of Clostridial bacteremia in 2 hospitals in La Crosse, Wisconsin in 1990-1997� Of 63,296 blood culture samples, 74 were positive for Clostridium species (0.12%)�Most common was C. Perfringens followed by C. septicum

� Possible source of Clostridium species � Colon – 12 pts (CRC-5, pseudomembranouscolitis-3, appendicitis, traumatic tear of rectum -1)� Lung – 6 pts (aspiration-3, Ca lung-2, empyema-1)� Unknown – 5 pts� Tubo-ovarian or endometrium – 4 pts� Biliary tract – 4 pts� Decubitus ulcer – 2 pts� Other – 8 pts� Contaminant – 5 pts

� 31 pts (67%) were aged >65 yrs old, 13 pts (28%) had DM, 22 pts (48%) had underlying malignancy� Overall mortality was 48%� Reflects poor general condition of patients� Conclude that it is a ‘potential serious clinical marker because of severity of associated illness in elderly & immunocompromised patients

CLOSTRIDIAL SEPTICAEMIA

� Clostridial Septicaemia in an urban hospital� Gregory Meyers. Surg, Gyn & Obst, April 1992, Vol 174, 291-296

� 56 patients at the NY Hospital with positive clostridialblood cultures� 22 were immunocompromised, 28 had malignancy usually GI� GI source of Clostridial presumed in 43 of 46 patients� C. perfringens was the most common, but C. septicum had the highest mortality� Mortality was highest in immunosuppressed patients� Recommend a thorough search of a GI source in such patients

OUR PATIENT�Where is the source of Clostridium� ?aspiration pneumonia� ?closed hip fracture� ?underlying GI pathology (anaemia/AXR)

FUSOBACTERIUM

FUSOBACTERIUM NECROPHORUM� Pleomorphic Gram-negative bacillus� short cocco-bacillus with occasional very long filamentous forms

� Non-motile� Non-spore forming� Facultative anaerobe� Normal inhabitant of alimentary tract of humans –opportunistic pathogen

INVASIVE DISEASE CAUSED BY FUSOBACTERIUM NECROPHORUM� Necrobacillosis� Isolating F. necrophorum from blood or tissue culture

� Lemierre’s syndrome� Hx of sore throat, anginal illness or comparable source

� Evidence of metastatic lesions

� Evidence of IJV thrombophlebitis

� Isolating F. necrophorum from blood culture or normally sterile site

LEMIERRE’S SYNDROME

EPIDEMIOLOGY� The current incidence rate ~ 0.8 cases per million in general population� Forgotten disease� Usually affect healthy young adults�Mortality rate was 90% prior to antibiotic therapy, but now generally quoted below 15%

CLINICAL DIAGNOSIS

RADIOLOGICAL IMAGING

CT Neck

DOPPLER ULTRASOUND

Thrombus in IJVLoss of vascular flow

TREATMENT� In the pre-antibiotic era, the only known treatment for Lemierre's syndrome was ligation of the affected internal jugular vein to prevent septicemia.� Today, the mainstay of therapy is a 4-to 6-week course of an antibiotic with activity against F necrophorum� penicillin G, clindamycin, or metronidazole

RESISTANCE

ANTICOAGULANT

CONCLUSION� 3 cases of anaerobic bloodstream infection� Case 1: Bacteroides fragilis� Case 2: Clostridium perfringens� Case 3: Fusobacterium necrophorum� Anaerobes is an uncommon yet important cause of bloodstream infection� Appropriate clinical specimen with proper collection, transport and handling are needed to diagnose anaerobic bacterial infection� Treatment are mostly empirical and sensitivity are rarely performed unless resistance suspected

QUESTIONS