Nosocomial and healthcare-associated infectionsDavid Lye FRACP, FAMSSenior consultant, Institute of Infectious Diseases and Epidemiology, Communicable Disease Centre, Tan Tock Seng HospitalAssociate professor, Yong Loo Lin School of Medicine, National University of Singapore

Definitions

• Hospital-acquired or healthcare-associated?• Centre for Disease Control/National

Healthcare Safety Network, January 2014– Healthcare-associated infections (HAI)– Localized or systemic condition resulting from an

adverse reaction to presence of an infectious agent(s) or its toxin(s) not present on admission to the acute care facility

Healthcare risk factors

Prevalence of healthcare-associated infections

183 hospitals11282 patients

93.2%

83%

Nosocomial pneumonia

Nosocomial pneumonia(VAP HAP HCAP)

• Increased hospital stay by 7-9 days• Excess cost >USD$40,000• 25% of ICU infections• >50% antibiotic use• Attributable mortality 33-50%

HCAP vs.CAPMore MRSA (31%), Pseudomonas (26%),Non-fermenting GNB (10%),Other Enterobacteriaceae (9%)LessPneumococcus, Haemophilus,Legionella

Risk factors and prevention

• General– Hand hygiene and contact

precaution to prevent cross-infection

• Mechanical ventilation– Non-invasive ventilation, avoid

intubation– Continuous suction of

subglottic secretions– Endotrachel tube cuff pressure

>20cm H20– Contaminated condensate

emptied and prevented from entering ETT

– Sedation protocol to accelerate weaning

– Adequate ICU staffing

• Aspiration, body positioning, enteral feeding– Semi-recumbent, 30-45

degrees– Enteral nutrition

• Colonisation– Daily interruption of sedation

and avoid paralytic agents• Stress bleeding prophylaxis,

transfusion and hyperglycaemia– H2 antagonist or sucralfate– Restricted transfusion trigger

policy– Insulin to maintain glucose 80-

110 mg/dL

Diagnosis

CXR new or progressiveFever or leukocytosisPurulent sputum or desaturation

CPIS ≤6 low probability of HAP

Culture-guided antibiotic therapy

Alternative diagnoses

Catheter-associated urinary tract infection

Catheter-associated UTI (CAUTI)• 40% of HAI’s• 15-25% in general hospitals had urinary

catheters for 2-4 days• 5-10% nursing home residents had urinary

catheters, some for years• Bacteraemia 1-4% with mortality ~13%• Extended length of stay 2 days• Cost CAUTI USD$676, bacteraemia USD$2836

Extraluminal 66%GPC 79%GNB 54%Yeast 69%

• Conditioning film of host urinary components• Bacteria attach by hydrophobic and electrostatic

interactions, and flagella• Cell division, additional planktonic bacteria,

extracellular matrix• Loosely packed 3-D structure with fluid channels for

nutrients and wastes• Survival advantage:

– Resistance to sheer forces and phagocytosis– Antimicrobial resistance

HICPAC 2009

Appropriate indications

IDSA 2010

Silver alloy catheters• A Cochrane Review of short-term urethral catheters in

hospitalized adults: Silver alloy catheters significantly reduced asymptomatic bacteriuria in catheters inserted for less than (RR:0.54; 95%CI: 0.43 to 0.67) and more than one week(RR:0.64, 95%CI: 0.51 to 0.80) [Cochrane Database Syst Rev. 2008;(2):CD004013]– Confounding by comparators as benefit significantly reduced with

different comparators• In bacterial adherence study, no difference was found

between silver alloy hydrogel urinary catheters and hydrogelcatheters [Clin Infect Dis. 2010;51:550-60]

Antimicrobial-coated catheters• Antimicrobial-coated urinary catheters including minocycline

and rifampicin (RR:0.36; 95%CI: 0.18 to 0.73) and nitrofurazone (RR:0.52, 95%CI: 0.34 to 0.78) significantly reduced asymptomatic bacteriuria in catheters inserted for less than one week but not in those inserted for more than one week [Cochrane Database Syst Rev. 2008;(2):CD004013]

Diagnostic criteria

• Urine culture or urinalysis was found to be non-specific for CAUTI in 14 patients with long-term urinary catheters [Am J Infect Control. 1985;13:154–160 ]

• A study of 56 patients with spinal cord disorders: Cloudy urine had an accuracy of 83.1%, pyuria Sn 82.8%, and fever Sp 99% but Sn 6.9% for CAUTI [J Spinal

Cord Med. 2009;32:568-73 ].

Urinalysis

• A study of 106 ICU patients: positive nitrite on urinalysis Sp 91.8% but Sn 29.5%– Leukocyte esterase, white cells and presence of yeast or

bacteria did not differentiate those with and without CAUTI [Intensive Care Med. 2006;32:1797-801 ]

• A study of 144 ICU patients: combining leukocyte esterase and nitrite Sn 87.2%, Sp 61.6%, PPV 30.6% and NPV 96.1% [Intensive Care Med. 2001;27:1842-7 ]

Evidence base: treatment• In a randomised study of 119 women with CAUTI, resolution occurred in

36% without antibiotic, 81% with single dose co-trimoxazole and 79% with 10 days of co-trimoxazole, after removal of urinary catheters [Ann Intern Med. 1991;114:713–9]

• Another randomised study of 619 patients with pyelonephritis and complicated UTI of whom 68 had urinary catheters, 5 days of levofloxacin versus 10 days of ciprofloxacin resulted in microbiological eradication of 79% versus 53% in the subgroup of catheterised patients [Urology. 2008;71:17–22]

• In another randomised study of 60 spinal cord patients with predominantly intermittent catheterisation comparing 3 versus 14 days of ciprofloxacin, microbiological cure was lower, and microbiological and clinical relapse higher in the 3-day group; however clinical cure was similar [Clin Infect Dis. 2004;39:658–64].

• In a randomised study of 54 patients with LT-UC in nursing home with CAUTI comparing replacement and non-replacement of urinary catheters before antibiotic, 93% in the group with replaced urinary catheters became afebrile by 72 hours [J Urol. 2000;164:1254–58].

Central line associatedbloodstream infection

Central line associated bloodstream infections (CLABSI)CDC HICPAC prevention guideline 2011

• Independently increased length of stay and hospital cost, but not mortality

Impact: death, length of stay and cost

Prevalence

Colonisation and bacteraemia

TreatmentRemoval of catheterDuration of antibioticComplicated vs. uncomplicated

TreatmentRemoval of catheterDuration of antibioticComplicated vs. uncomplicated

Catheter salvage and antibiotic lock therapy

Clostridium difficileassociated diarrhoea

Epidemiology• Rising incidence since

2001• Severe and fatal CDAD• Epidemic strain

– North American Pulse Field Type 1 (NAP1) or PCR ribotype 027

– Increased toxins A and B, fluoroquinolone resistance, binary toxin

– Deletion tcdC which inhibits toxin production

Risk factors

Clinical features and epidemiologyICHE 1995; 16: 459

• Definition: diarrhoea (6 watery stools 36 hours, 3 unformed stools 24 hours 2 days, 8 unformed stools 48 hours), pseudomembrane endoscopy, toxin A or B stool, +ve stool culture and no other cause +/- antibiotic use– <1% ileus without diarrhoea

• Carriage common in infants, markedly decline by 1 year• Adult carriage 2% Sweden to 15% Japan• 10% hospital patients colonised• Primary cause antibiotic-colitis, 15-25% antibiotic diarrhoea

– 30% hospital patients diarrhoea CD +ve– Rehabilitation 25%– Community <1/10000 antibiotic prescriptions

• Initial stool negative, test another (increased yield 10% for 3 stools)

• 20% initial culture-negative adults nosocomially acquire CDAD (high endemicity) 2/3 remain asymptomatic– 8% per week– 13% 1-2 weeks, 50% >4 weeks (CID 1998; 26: 1027)

– Median time from admission to CDAD 13 days (NEJM 2005; 353: 2442), 21 days (EID 2003; 9: 730)

Clinical features and epidemiologyICHE 1995; 16: 459

• 3 or more unformed stools in last 24 hours• Testing:

– Only on unformed stool– Not on asymptomatic or test of cure or repeat in

same episode of diarrhoea– EIA sub-optimal sensitivity, 2-step GDH (with cell

cytotoxin assay or culture) promising, PCRsensitive and specific

Treatment

Cure higher with oral vancomycinfor severe CDAD onlyRelapse similar (10%)

Fidaxomicin less relapse vs. vancomycin

AJG 2002;97:1769

Surgical site infections

Surgical site infections (SSI)ICHE 1999;20:247

• Third commonest HAI• 14-16% of HAI’s• Among deaths in surgical patients with SSI,

77% related to SSI, 93% due to organ space SSI• Increased length of stay by 10 days• Increased cost by USD$2000

Diagnosis: SSI

ICHE 1999; 20: 247

ICHE 1999; 20: 247

SSI risk stratification and surveillanceICHE 1999; 20: 247

• Within clean wound category, SSI risk 1.115.8% (SENIC) and 1.05.4% (NNIS)

• SENIC, 4 independent risk factors (abdominal operation, >2 hours, contaminated or dirty wound, >3 discharge diagnoses), each given 1 point if present, score 0-4

• NNIS risk index 0-3, 1 point if present for (1) ASA >2 (2) contaminated or dirty wound (3) operating time >T hours [75th percentile for specific operation]

• Inpatient, post-discharge and outpatient surveillance– Direct and indirect detection – 1284% SSI detected after discharge– Most SSI evident within 21 days

Risk index and SSI rates

Wound category

SSI rate, %

Clean 1.32.9

Clean contaminated

2.47.7

Contaminated 6.415.2

Dirty 7.140

NNIS risk index SSI rate, %

0 1.5

1 2.9

2 6.8

3 13

Surgical site infections• Patient factors• Preoperative

– Skin preparation– Hand and forearm

antisepsis• Intraoperative

– Operating room environment

– Surgical attire and drapes– Asepsis and surgical

techniques• Postoperative

– Incision care

ICHE 1999;20:247

Pre-operative antibiotic prophylaxisICHE 1999; 20: 247

• 4 principles:– Evidence of efficacy or effect of SSI catastrophic– Antibiotic: safe, inexpensive, bactericidal, active against probable

contaminants– Time the infusion so bactericidal drug level in tissue and serum at skin

incision– Maintain therapeutic level until at most a few hours after incision is closed

• Indicated for all operations entering hollow viscus and clean operations where prosthetic material inserted or effect of SSI catastrophic

• Need for second dose depends on: tissue level by standard therapeutic dose, serum half life, MIC90 of anticipated SSI pathogens

• Antibiotic given no more than 30 minutes before skin incision– Vancomycin needs 1 hour infusion

Several good guidelines

Evidence: 1=meta-analysis, 2=RCT, 3=well-designed study, 4=opinion

Surgical antibiotic prophylaxis

Antimicrobial prophylaxis in colorectal surgery: a systematic review of randomized controlled trialsBr J Surg 1998;85:1232

• Trials from 1984 to 1995, n=147• Effective for prevention of SSI in colorectal surgery• No significant difference between many different

regimens– Not good: metronidazole OR doxycycline OR piperacillin

alone, PO neomycin and erythromycin

• First-generation cephalosporins as good as new-generation cephalosporins (OR 1.07, 95% CI 0.54-2.12)

Visceral, trauma and vascular surgeryIV cefuroxime 1.5G +/-metronidazole 500mg

Right timing more importantWith right timing, re-dosing >2 T1/2 of prolonged surgery additional benefit

Duration of surgical antibiotic prophylaxis

• J Thorac Cardiovasc Surg 1977;73:470– Prospective double-blind study, 2 vs. 6 days of cephalothin, prosthetic

valve surgery– Sternal wound infection 2.1% vs. 2.8%

• Aust N Z J Surg 1998;68:388– Meta-analysis of prospective, randomised studies, same drug in both

arms– No advantage of multiple vs. single dose– No difference: beta-lactam vs. others, >24 vs. ≤24 hours

• BMJ 1979;6165:707– Prospective, 3 doses of cephaloridine vs. 2 weeks flucloxacillin, THJR– Overall deep infection 1.3%, no difference between 2 arms

• Br J Surg 1998;85:1232– Single dose pre-op as effective as long-term post-op (OR 1.17, 95% CI

0.90-1.53)

Control blood sugar for DM

Normothermia for all butcardiac surgery

Pre-operative hair removal to reduce surgical site infectionsCochrane Database Systematic Rev 2006;2:CD004122

• Assess RCT of hair removal vs. no hair removal, different methods and times

• N=11• 3 RCT compared depilatory cream/razor vs. no hair removal no difference in SSI

• 3 RCT compared shaving with clipping more SSI with shaving (OR 2.02, 95% CI 1.21-3.36)

• 7 RCT compared shaving with depilatory cream more SSI with shaving (OR 1.54, 95% CI 1.05-2.24)

• 1 RCT compared each compared shaving OR clipping on day of surgery vs. day before surgery no difference in SSI

Use clippers or depilatory cream, or do not shave

Questions?

David_lye@ttsh.com.sg