Infections in ICUs

Dr Rajesh Karyakarte MD

Dean,

Government Medical College,Akola

INFECTIONS IN SICU AND ICU

WHAT IS AN ICU?

• An intensive care unit (ICU) is defined as a specially staffed, specialty equipped, separate section of a hospital dedicated to the observation, care, and treatment of patients with life threatening illnesses, injuries, or complications from which recovery is possible

HISTORY

• ICU care dates back to the polio epidemic in 1950s

• The technique of controlled ventilation was then extended to patients with drug overdose, tetanus, and chest trauma, with resultant improvement in survival

Yeolekar ME, Mehta S. ICU Care in India - Status and Challenges. Indian Journal of Basic and Applied Medical Research 2014: 3, Issue- 4, 46-63.

TYPES OF ICUs

• Medical, • Surgical, • Cardiac, • Neurology, • Paediatric and • Neonatal

INFECTIONS IN ICUs

• Patients in intensive care units (ICUs) have a higher risk of acquiring hospital-associated infections than those in non-critical care areas

• Up to 45% of hospital-acquired infections occur in ICU patients, although these patients occupy only 8% of hospital beds

Donowitz LG, Wenzel RP, Hoyt JW. High risk of hospital-acquired infection in the ICU patient. Crit Care Med 1982; 10:355-357

INFECTIONS IN ICUs

• ICU-acquired infection rates are five to ten times higher than hospital-acquired infection rates in general ward patients

• The ICUs are an area of considerable antibiotic use in which antibiotic-resistant organisms are prevalent

Weinstein RA. Nosocomial infection update. Emerg Infect Dis 1998;4:416-420 Albrich WC, Angstwurm M, Bader L, Gartner R. Drug resistance in intensive care units. Infection 1999;27(suppl 2): S19-23

INFECTIONS IN ICUs

• ICU patients with infections can be divided into three groups, those with: • Community-acquired infections, • Hospital-acquired infections before

transfer to the ICU, • ICU-acquired infections

INFECTIONS IN ICUs

• ICU patients with a stay of more than 24 hours, have 18.9% probability of developing infection during their ICU stays

Alberti C, Brun-Buisson C, Burchardi H, et al. Epidemiology of sepsis and infection in ICU patients from an international multicentre cohort study. Intensive Care Med 2002; 28:108-121

SITES OF INFECTION

• The most common sites of infection are• Lungs (pneumonia, 46.9%); • Other respiratory tract (17.8%); • Urinary tract (17.6%); • Bloodstream (12%);

Vincent JL, Bihari DJ, Suter PM, et al. The prevalence of nosocomial infection in intensive care units in Europe. Results of the European Prevalence of Infection in Intensive Care (EPIC) Study. EPIC International Advisory Committee. JAMA 1995;274:639-644

SITES OF INFECTION

• Other common sites of infection are• Wound (6.9%); • Ear, nose, and throat (5.1%); • Skin and soft tissue (4.8%);


SITES OF INFECTION

• Other common sites of infection are• Gastrointestinal tract (4.5%); • Cardiovascular system, including

phlebitis (2.9%); and • Clinical sepsis (2%)


• Major sites of infection in medical and surgical patients in medical/surgical intensive care units (U.S. National Nosocomial Infections Surveillance 1992-1998)

• BSI, bloodstream infection

• UTI, urinary tract infection

• PNE, pneumonia

SITES OF INFECTION

Semin Respir Crit Care Med. 2003;24(1) © 2003 Thieme Medical Publishers

PATHOGENS IN ICU-ACQUIRED INFECTIONS

Richards MJ, Edwards JR, Culver DH, Gaynes RP. Nosocomial infections in combined medical-surgical intensive care units in the United States. Infect Control Hosp Epidemiol 2000;21:510-515


9. Richards MJ, Edwards JR, Culver DH, Gaynes RP. Nosocomial infections in combined medical-surgical intensive care units in the United States. Infect Control Hosp Epidemiol 2000;21:510-515





ANTIMICROBIAL RESISTANCE OF ICU PATHOGENS

• Antimicrobial-resistant pathogens frequently cause ICU-acquired infection, and

• Their prevalence can vary enormously depending on geographic location as well as location among ICU types

Fridkin SK, Gaynes RP. Antimicrobial resistance in intensive care units. Clin Chest Med 1999;20:303-316, viii

RATES AND PREVALENCE OF ICU-ACQUIRED INFECTIONS

• The EPIC study in 1992 reported a prevalence of ICU infections of 20.6%

• An incidence density of 23.7 episodes per 1000 patient-days was reported from 119 U.S. ICUs from surveillance data between 1986 and 1990

Vincent JL, Bihari DJ, Suter PM, et al. The prevalence of nosocomial infection in intensive care units in Europe. Results of the European Prevalence of Infection in Intensive Care (EPIC) Study. EPIC International Advisory Committee. JAMA 1995;274:639-644Jarvis WR, Edwards JR, Culver DH, et al. Nosocomial infection rates in adult and pediatric intensive care units in the United States. National Nosocomial Infections Surveillance System. Am J Med 1991;91(3B):185S-191S

RATES AND PREVALENCE OF ICU-ACQUIRED INFECTIONS

• The most significant risk factor for most ICU-acquired infections is the use of• Invasive devices, including •Mechanical ventilation, • Central venous catheters, and • Urinary catheters


DEVICE-UTILIZATION RATIOS BY ICU TYPE

• There are considerable differences in rates of device use between different types of ICU and within a given ICU type

• Device-utilization is significantly higher in major teaching hospitals as compared with other hospitals for all three major devices

Richards MJ, Edwards JR, Culver DH, Gaynes RP. Nosocomial infections in medical intensive care units in the United States. National Nosocomial Infections Surveillance System. Crit Care Med 1999;27:887-892

DEVICE-UTILIZATION RATIOS BY ICU TYPE

*Urinary catheter utilization = (number of urinary catheter-days)/(number of patient-days). **Central venous line utilization = (number of central line-days) /(number of patient-days). ***Ventilator utilization = (number of ventilator-days)/(number of patient-days).U.S. National Nosocomial Infections Surveillance 1995-2001

COMPARING INTENSIVE CARE UNIT TYPES

• The types of infection and the pathogens vary between different ICU types

MEDICAL-SURGICAL INTENSIVE CARE UNITS

• Combined medical-surgical ICUs (MSICUs) is defined as an ICU where neither medical nor surgical patients represent more than 80% of total patients in the unit

SURGICAL INTENSIVE CARE UNITS

• Nosocomial pneumonias constitute 43% of hospital-acquired infections in SICUs

• VAP rates in general SICUs are higher than cardiothoracic ICUs but lower than neurosurgical, burn, and trauma ICUs

• The second most common infection in SICUs is UTI (25%)

SURGICAL INTENSIVE CARE UNITS

• Bacteriology of SICUs have changed over time• Enterobacter sp and Acinetobacter in

VAP, and Candida in UTIs• Gram-negative bacilli and Enterococcus

have replaced S. aureus as the most common isolates responsible for surgical site infections

PEDIATRIC INTENSIVE CARE UNITS

• BSI is the most common• Urinary catheter use is markedly lower

than in adult ICUs, and • Gram-negative bacteria were more

frequently reported as causing primary BSIs than in adults, and Enterobacter sp is most common

PEDIATRIC INTENSIVE CARE UNITS

• Viral infections are significant more common

• The problems of antibiotic resistance, particularly, vancomycin-resistant enterococci (VRE), is less than in adult ICUs

NEONATAL ICU (NICU)

• NICU patient infection rates are reported to range from 6 to 25%

• Infants with birth weights < 1500 g have significantly higher rates of infection

NICU

• Primary BSIs are the most frequent hospital-acquired infection in all birth weight groups

• All aspects of immune function are immature in a neonate admitted in NICU

NICU

• Fungal infections in neonates, in particular C. albicans and C. parapsilosis, have increased

• Risk factors include broad-spectrum antibiotic use, intravenous fat emulsions, and use of central lines

NICU

• Catheter colonization rates are significantly greater than those reported in adults

• Gram-positive cocci are the most common nosocomial pathogens in the neonate

NICU

• Group B streptococci were associated with 46% of maternally acquired BSIs and

• CONS, with 58% of non-maternally acquired BSIs in NNIS surveillance between 1986 and 1994

TRAUMA INTENSIVE CARE UNITS

• About 40% of patients with traumatic injuries are admitted to the ICU

• Sepsis is a major cause of mortality in these patients

• Device-utilization rates are among the highest compared with other ICU types


• In one cohort of 10,557 patients, the nosocomial infection rate was 20%

• ICU-acquired infection was four times more common in blunt versus penetrating injury


• The most common infections are respiratory infection, followed by UTI

• Surgical wound infections and skin/soft tissue infections accounted for 18% and 13% of infections, respectively


• Trauma patients are significantly more likely to develop pneumococcal or Haemophilus influenzae pneumonia than patients from other ICUs


• S. aureus has consistently proven to be the most frequently isolated pathogen in the trauma population

• Head-injured patients colonized with S. aureus are at high risk for S. aureus pneumonia

BURN INTENSIVE CARE UNITS

• Overall, Burn ICU-acquired infection rates are the highest reported despite lower device-utilization rate compared with other ICU types


• These patients are at high risk due to factors such as • Burn-related immune suppression, • Loss of skin and mucous membrane barriers, • Inhalation injury, • Prolonged hospitalization, and • Broad-spectrum antibiotic use


• In a Swedish study, the most common infection was • Burn wound infection (60%), followed

by • BSI (20%), UTI (10%), and• Pneumonia (10%)


• Prolonged length of stay correlated with burn wound colonization by • Enterobacteriaceae, P aeruginosa, and S

aureus in one study• P aeruginosa was the most frequently

isolated pathogen in several studies


• In a study of burn patients that were mechanically ventilated• Patients became colonized by the

second week with Acinetobacter, which became the most common organism isolated in VAP, BSI, and wound swab cultures

MEDICAL INTENSIVE CARE UNITS

• NNIS surveillance data from 112 medical ICUs from 1992 to 1997 reported that • UTIs were the most common type of

infection (31%) followed by • Pneumonia (27%) and • BSIs (19%)


• The infection rate is 19.9 per 1000 patient-days

• Gram-positive pathogens account for 65% of BSIs

• Enterococci were more frequently reported than S. aureus as pathogens in primary BSIs


• Fungi constituted 40% of urinary isolates• Enterococcus was as common a urinary

pathogen as E. coli• Third-generation cephalosporin and

vancomycin use was considerably higher in MICUs than in MSICUs

INTENSIVE CORONARY CARE UNITS

• Intensive coronary care unit (CCU) patients differ in risk of nosocomial infection compared with other ICU patients

• They are frequently admitted directly to the unit without prior antibiotic use or exposure to other hospital pathogens

INTENSIVE CORONARY CARE UNITS

• Device-utilization rates are the lowest among the different adult ICU types

• The urinary tract is the most frequent site of infection

• NNIS surveillance data from 93 CCUs (1992-1997) reported an overall infection rate of 10.6/1000 patient-days

OUTBREAKS IN ICUs

• Outbreaks are common in the ICU • Nosocomial outbreaks occur at a

frequency of 1 in 10,000 to 12,000 hospital discharges

OUTBREAKS IN ICUs

• Over half are caused by gram-negative organisms, although S. aureus is the single most common cause

• However the majority of isolates reported were multi-resistant gram-negative bacilli, most frequently Acinetobacter, Enterobacter sp, and P. aeruginosa

OUTBREAKS IN ICUs

• Over half of the published outbreaks were in NICUs

• This may also reflect the particular susceptibility of low birth weight and premature infants to sepsis

OUTBREAKS IN ICUs

• Outbreaks may be of either exogenous or endogenous origin• Exogenous infections usually have a

common inanimate or animate source, whereas

• Endogenous infections are transmitted from the patient with the outbreak strain

OUTBREAKS IN ICUs

• The epidemiology of resistant organisms is characterized by multiple monoclonal outbreaks, followed by endemic colonization in the ICU

• Indirect transmission from patient to patient on the hands of health care workers becomes the most important mode of transmission

OUTBREAKS IN ICUs

• In fact, the majority of recent outbreaks identified problems with infection control measures such as handwashing practices and environmental disinfection

• The molecular methods have a fundamental role in understanding the epidemiology of outbreaks in ICUs

RISK FACTORS FOR ICU-ACQUIRED INFECTIONS

• The most significant risk factor for nosocomial pneumonia in ICU patients is endotracheal intubation with mechanical ventilation, which increases the risk of pneumonia by 6 to 21 times


• Regarding other sites of infection, central catheters account for 97% of all nosocomial BSIs. Scheduled replacement of catheters has not been shown to prevent infection


• Duration of urinary catheterization is the most important risk factor for acquisition of nosocomial UTIs

• Of uninfected patents, 2 to 16% will acquire a UTI for each day of catheterization


• Naso-tracheal intubation is the most significant risk factor for acquisition of nosocomial sinusitis

• Congestion of nasal blood vessels due to positive pressures used in mechanical ventilation, and the absence of gravitational forces in the supine position may impair sinus drainage

MORTALITY FROM ICU-ACQUIRED INFECTIONS

• Many international studies have reported high rates of crude mortality from ICU-acquired infections, reflecting both • the severity of the underlying illnesses

in patients acquiring these infections, and

• any attributable mortality from the ICU-acquired infection


Pneumonia

• Crude mortality rates for nosocomial pneumonia in the ICU have been reported as approximately 50%

• It has been generally accepted that VAP has significant attributable mortality


Pneumonia

• High-risk pathogens (P. aeruginosa, Acinetobacter, and Stenotrophomonas maltophilia) may also be independent risk factors for mortality


Bloodstream Infections

• Carefully designed, large, and recent studies report substantial crude and attributable mortality from these infections

IMPACT OF SPECIFIC PATHOGENS AND ANTIBIOTIC RESISTANCE

• In a large point prevalence study• Mortality was three times higher in

patients with methicillin-resistant S. aureus (MRSA) as compared with methicillin-sensitive S. aureus with lower respiratory tract infections

Ibelings MM, Bruining HA. Methicillin-resistant Staphylococcus aureus: acquisition and risk of death in patients in the intensive care unit. Eur J Surg 1998;164:411-418


• Vancomycin resistance (as compared with vancomycin sensitivity) of enterococcal bacteremia was associated with prolonged hospital stay but not increased mortality in an MSICU

Mainous MR, Lipsett PA, O'Brien M. Enterococcal bacteremia in the surgical intensive care unit: does vancomycin resistance affect mortality? The Johns Hopkins SICU Study Group. Arch Surg 1997;132:76-81


• In patients with antibiotic-susceptible gram-negative bacteremias and antibiotic-resistant gram-negative bacteremias, there was no difference in mortality


• P. aeruginosa, Acinetobacter baumannii infection,

and Candida infections have been reported to have significant attributable mortality

COSTS OF ICU-ACQUIRED INFECTIONS

• Several reports identify attributable costs to ICU-acquired BSIs and pneumonia,

• Warren et al noted longer hospital and ICU stays in survivors of primary BSIs

Warren DK, Zack JE, Elward AM, Cox MJ, Fraser VJ. Nosocomial primary bloodstream infections in intensive care unit patients in a nonteaching community medical center: a 21-month prospective study. Clin Infect Dis 2001;33:1329- 1335


• Intubated trauma patients with pneumonia required prolonged care, and hospital costs were 1.5 times higher

• Infections with MRSA and VRE lead to increased length of stay and cost of care in comparison to infections with sensitive isolates


• Additional nursing workload in managing ICU patients with multi-resistant bacteria may increase costs

NURSING AND MEDICAL STAFFING AND INFECTION RATES

• Several reports have indicated that nurse understaffing or nursing staff experience may affect ICU-acquired infection rates


• Patient acquisition of MRSA in an English ICU was found to correlate with peaks of nursing workload and reduced nurse:patient ratios

Vicca AF. Nursing staff workload as a determinant of methicillin-resistant Staphylococcus aureus spread in an adult intensive therapy unit. J Hosp Infect 1999;43:109-113


• Physicians-in-training has been shown to increase the use of maximal barrier precautions during central line insertion and to reduce the risk for central line-associated BSIs

Sherertz RJ, Ely EW, Westbrook DM, et al. Education of physicians-in-training can decrease the risk for vascular catheter infection. Ann Intern Med 2000;132:641-648

ANTIBIOTIC USE IN INTENSIVE CARE UNITS

• Antimicrobial use and antimicrobial resistance is higher in ICUs and varies enormously between hospitals

• Antimicrobial resistance in the ICU impact mortality as it affects appropriateness of empiric therapy


• In a study of 2000 ICU patients• inadequate antimicrobial treatment of

ICU nosocomial infections occurred in 8.5% of patients and was associated with substantial mortality (52.1%)

• It was most important factor affecting hospital mortality

Dupont H, Mentec H, Sollet JP, Bleichner G. Impact of appropriateness of initial antibiotic therapy on the outcome of ventilator-associated pneumonia. Intensive Care Med 2001; 27:355-362


• In another study, inappropriate initial antibiotic treatment of VAP in the first 48 hours increased ICU length of stay (12 days vs 24 days)

• It increased crude hospital mortality despite equal severity of illness at the time of diagnosis of VAP

Dupont H, Mentec H, Sollet JP, Bleichner G. Impact of appropriateness of initial antibiotic therapy on the outcome of ventilator-associated pneumonia. Intensive Care Med 2001; 27:355-362

SURVEILLANCE OF ICU-ACQUIRED INFECTIONS

• SENIC study (1985) showed that surveillance is the key element of effective infection control programs

• SENIC = Study of the Efficacy of Nosocomial Infection Control

Haley RW, Morgan WM, Culver DH, et al. Update from the SENIC project: hospital infection control: recent progress and opportunities under prospective payment. Am J Infect Control 1985;13:97-108


• Monitoring of infection or colonization of patients with antimicrobial-resistant organisms

• Selective screening for MRSA nasal carriage and interventions caused a reduction of MRSA incidence in the ICU from 5.8 to 2.6%


• Molecular typing of organisms helps in epidemiology of hospital-acquired infections

• It is now fundamental tool in understanding transmission of ICU pathogens


• Molecular typing helps in differentiating a series of sporadic infections against outbreaks with a single clone

Thank you

Health & Medicine

Infections in ICUs