Pathophysiology and management of healthcare associated infection

1. Healthcare-associated
Infections
Dr Kaushal Deep Singh
Lecturer, Department of Surgery
UPUMS, Saifai

2. Introduction
 Healthcare-associated infections (HAI) are defined as infections
not present and without evidence of incubation at the time of
admission to a healthcare setting.
 Most infections that become clinically evident after 48 hours of
hospitalization are considered hospital-acquired.
 Infections that occur after the patient is discharged from the
hospital can be considered healthcare-associated if the organisms
were acquired during the hospital stay.
 Term healthcare-associated infections has replaced old ones such
as nosocomial, hospital-acquired or hospital-onset infections.

3. Etiopathogenesis
 3 major sites of healthcare-associated infections-
 bloodstream infection,
 pneumonia, and
 urinary tract infection
 Source of infection may be –
 Endogenous
 Exogenous
 Endogenous sources include body sites normally inhabited by
microorganisms, e.g. nasopharynx, GI, or genitourinary tracts.
 Exogenous sources include those that are not part of the patient,
e.g. visitors, medical personnel, equipment and the healthcare
environment.

4. Etiopathogenesis
 Patient-related risk factors for invasion of colonizing pathogen
include
severity of illness
underlying immunocompromised state
length of in-patient stay.
 Central-line associated blood stream infections (BSI), ventilator
associated pneumonias (VAP), and catheter-associated urinary
tract infections are the main types of HAI’s.
 Healthcare-associated infections can be caused by viral, bacterial,
and fungal pathogens.

5. Etiopathogenesis
 Risk factors for the development of catheter-associated
bloodstream infections include
catheter hub colonization,
exit site colonization,
duration of parenteral nutrition,
neutropenia,
prolonged catheter dwell time (>7 d),
use of percutaneously placed CVL (higher than tunneled or
implanted devices), and frequent manipulation of lines.
 Disruption of catheter dressings has also been shown to increase
risk for catheter-related infections.

6. Etiopathogenesis
 Risk factors for the development of ventilator-associated
pneumonia (VAP)-
Re-intubation,
Prolonged intubation,
Immunodeficiency, and immunosuppression,
Prior episode of bloodstream infection.
Risk factors for the development of healthcare-associated
urinary tract infection include-
bladder catheterization,
prior antibiotic therapy,
cerebral palsy.

7. Epidemiology
 Healthcare-associated infections are estimated to occur in 5% of
all hospitalizations developed countries to 8.7% in developing
countries.
 Reports of certain HAI’s as high as 25%.
 Gender: No reported gender predilection.
 Bloodstream infections, followed by pneumonia and urinary tract
infections are the most common healthcare-associated infections
in children.
 Urinary tract infections are the most common healthcare-
associated infections in adults.

8. Clinical Presentation
 Pathogens should be investigated in all febrile patients who are
admitted for a non-febrile illness or those who develop clinical
deterioration unexplained by the initial diagnosis.
 About 91% of bloodstream infections are in patients with central
intravenous lines (CVL), 95% of pneumonia cases are in patients under
going mechanical ventilation, and 77% of urinary tract infections are in
patients with urinary tract catheters.
 Systemic signs and symptoms of infection eg, fever, tachycardia,
tachypnea, skin rash, general malaise.
 Endotracheal tube may be associated with sinusitis, tracheitis, and
pneumonia; an intravascular catheter may be the source of phlebitis or
line infection; and a Foley catheter may be associated with a urinary
tract infection.

9. Clinical Presentation
 Patients with pneumonia may have fever, cough, purulent sputum and
abnormal chest auscultatory findings such as decreased breath
sounds, crackles or wheezes.
 Patients with urinary tract infection may present with or without fever.
Patients with cystitis can have suprapubic tenderness while those with
pyelonephritis can have costovertebral tenderness. Upon inspection,
their urine can be cloudy and foul-smelling.
 Neonates on the other hand usually do not present with any of the
above findings and may have very subtle and nonspecific signs of
infection.
 Signs of infection can include temperature and/or blood pressure
instability, apnea, bradycardia, lethargy, fussiness, and feeding
intolerance.

10. New Delhi metallo-beta-lactamase 1
 It is an enzyme that makes bacteria resistant to a broad range of
beta-lactam antibiotics specifically carbapenem family, which are a
mainstay for the treatment of antibiotic-resistant bacterial
infections.
 The gene for NDM-1 is one member of a large gene family that
encodes beta-lactamase enzymes called carbapenemases.
 Bacteria that produce carbapenemases are often referred to in the
news media as "superbugs" because infections caused by them are
difficult to treat.
 Such bacteria are usually susceptible only to polymyxins and
tigecycline.

11. New Delhi metallo-beta-lactamase 1
 NDM-1 was first detected in a Klebsiella pneumoniae isolate from a Swedish
patient of Indian origin in 2008.
 Later detected in bacteria in India, Pakistan, the United Kingdom, the United
States, Canada, and Japan.
 The most common bacteria that make this enzyme are Gram-negative such
as Escherichia coli and Klebsiella pneumoniae, but the gene for NDM-1 can
spread from one strain of bacteria to another by horizontal gene transfer.

12. Differential Diagnosis
 Acinetobacter
 Adenoviruses
 Bacterial Sepsis
 Burn Wound Infections
 Clostridium Difficile Colitis
 Colitis
 Croup
 Enterobacter Infections
 Enterococcal Infections
 Escherichia Coli Infections
 Group A Streptococcal
Infections
 H1N1 Influenza (Swine Flu)
 HIV Disease
 Hepatitis A
 Hepatitis B
 Hepatitis C
 Toxic Shock Syndrome
 Urinary Tract Infection
 Pseudomonas Infection
 Respiratory Syncytial Virus Infection
 Rhinovirus Infection
 Staphylococcal Infections
 Staphylococcus Aureus Infection
 Stenotrophomonas Maltophilia
 Thrush
 Tuberculosis
 Legionella Infection
 Measles
 Hospital-Acquired Pneumonia
(Nosocomial Pneumonia) and
Ventilator-Associated
Pneumonia
 Nursing Home Acquired
Pneumonia
 Parainfluenza Virus Infections
 Bacterial Endocarditis
 Candidiasis
 Enteroviral Infections
 Fungal Endocarditis
 Varicella-Zoster Virus
 Influenza

13. Work-Up
Caution should be taken when interpreting laboratory results
because not all bacterial or fungal growth on a culture are
pathogenic.
Consider the following:
Clinical presentation of the patient
Reason for obtaining the test
Process by which the specimen was obtained
Presence of other supporting evidence of infection

14. Work-Up
Known "contaminant" skin organisms such as coagulase-negative
staphylococcus, viridans streptococcus, Micrococcus,
Corynebacterium, Propionibacterium, and Bacillus species
Should not easily be dismissed as contaminants if they grew on
cultures of normally sterile body fluids.
Repeating cultures may help establish presence or absence of
infection.
Fungal growth on a blood culture should never be dismissed as
"contamination.“

15. Work-Up
Bloodstream infections (catheter-associated bloodstream
infection)
 Differential time to positivity of paired blood cultures is simplest measure.
 Catheter is confirmed as the source of bloodstream infection if the blood
culture from the catheter shows microbial growth 2 hours or more earlier
than a peripheral blood culture obtained at the same time.
 Quantitative cultures of blood obtained from the catheter and peripheral
vein and also, quantitative culture of catheter segment.

16. Work-Up
Multiple blood cultures over 24 hours and appropriate volume of
blood sample may increase the yield in cases of intermittent or
low-inoculum bacteremia.
Fungal cultures should be obtained if fungal infection is
suspected.
In immunocompromised patients, special studies are
occasionally requested, such as cultures for nocardia and atypical
mycobacteria, cytomegalovirus, and cytomegalovirus
antigenemia detection.

17. Work-Up
Pneumonia
 Acute phase reactants (peripheral WBC count, erythrocyte sedimentation
rate, C-reactive protein) may be elevated.
 Decreasing oxygen saturation and worsening hemodynamic status are clues
to the presence of pneumonia.
 Presence of a new infiltrate on chest radiograph is supporting evidence of
pneumonia.
 Sputum gram stain and cultures may be useful.
 An acceptable sample should have less than 10 squamous epithelial cells,
more than 25 neutrophils per low-power field and culture growing a
predominant organism.

18. Work-Up
 Materials obtained via suctioning of endotracheal, nasotracheal, and
tracheostomy tubes may not be reliable.
 Other methods to obtain specimens for microbiologic evaluation include
bronchoalveolar lavage and thoracocentesis.
 Tracheobronchial colonization, ventilator-associated tracheobronchitis, and
ventilator-associated pneumonia should be differentiated.
 Rapid diagnostic tests may be valuable in specific cases. Examples include
Direct fluorescent antibody test for Legionella organisms;
Polymerase chain reaction tests for Bordetella pertussis;
Immunofluorescence tests for influenza, respiratory syncytial virus, and Pneumocystis
jiroveci; and
Modified acid-fast stains for mycobacteria.

19. Work-Up
Urinary tract infection
 Urinalysis and urine culture along with clinical findings are essential in
differentiating asymptomatic bacteriuria, cystitis and pyelonephritis.
 Presence of pyuria, bacteria, nitrites and leukocyte esterase on urinalysis
makes urinary tract infection likely.
 Urinary tract infection is highly likely when the urine culture (obtained by
transurethral catheterization) is growing more than 100,000 colony-forming
units/mL of a single organism.
 Renal ultrasonography may also help detect abscesses or phlegmons in
patients unresponsive to antibiotic therapy.
 X-ray KUB to rule out pre-existing stones.

20. Work-Up
Other healthcare-associated infections
 Cultures of specimen from the surgical site infection may reveal pathogens.
 Detection of rotavirus antigen in stool confirms gastroenteritis due to
rotavirus.
 Available tests to detect Clostridium difficile include stool culture, enzyme
immunoassay for toxin detection, and polymerase chain reaction tests.
Imaging Studies
 Special imaging techniques (eg, ultrasonography, CT scan, MRI) may be
helpful in evaluating obscure-site infections.

21. Treatment and Management
 Symptomatic treatment of shock, hypoventilation, and other complications
should be provided, along with administration of empiric broad-spectrum
antimicrobial therapy.
Bloodstream infections
 Line removal should be considered if
Line is no longer needed;
Infection is caused by S aureus, Candida species, or mycobacteria;
Patient is critically ill;
Patient fails to clear bacteremia in 48-72 hours;
Symptoms of bloodstream infection persist beyond 48-72 hours;
Noninfectious valvular heart disease, endocarditis, metastatic infection, or septic
thrombophlebitis is present.

22. Treatment and Management
Bloodstream infections (cont’d)
 Antibiotics with coverage against gram-positive and gram-negative organisms,
including Pseudomonas, should be empirically started.
 Antifungal therapy (eg, fluconazole, caspofungin, voriconazole, amphotericin B)
in some cases are added to empiric antibiotic coverage.
 Antiviral therapy (eg, ganciclovir, acyclovir) can be used in the treatment of
suspected disseminated viral infections.
 Duration of therapy depends on several factors, including isolated pathogen,
retention of catheter, or presence of complications (endocarditis, sepsis).
 For most bacterial organisms, the duration of therapy is 10-14 days after blood
cultures become negative.

23. Treatment and Management
Pneumonia
 Initial empiric antibiotic therapy should be broad and later on streamlined based
on results of examination and cultures of sputum, endotracheal suction material
and bronchial lavage wash.
 Choice of empiric antibiotic coverage should take into consideration the risk for
multidrug-resistant (MDR) pathogens.
 Risk factors for MDR include antimicrobial therapy over the past 90 days, current
hospitalization of 5 days or more, high frequency of antibiotic resistance in the
community, or hospital and immunosuppression.
 Ventilator-associated pneumonia (VAP) is treated for 14-21 days.
 Antiviral medications against influenza used to treat symptomatic patients and
patients with immunodeficiency or chronic lung diseases.

24. Treatment and Management
Urinary tract infection
 Indwelling catheters should be removed if possible.
 In some cases, removal of catheter may result in spontaneous
resolution of bacteriuria or asymptomatic cystitis.
 Empiric antibiotic and antifungal therapy should be considered to
avoid major complications, including pyelonephritis, renal damage,
and bloodstream infections.
 Duration of therapy recommend at least 10-14 days of therapy with
sepsis, pyelonephritis, or urinary tract abnormalities.

25. Treatment and Management
Surgical-site infection
Surgical-site infections (SSIs) should be managed with a
combination of surgical care and antibiotic therapy. Antibiotic
coverage should be modified once culture results are available.
Severe infections such as streptococcal gangrene and extensive
tissue necrosis need aggressive surgical intervention.

26. Treatment and Management
Other healthcare-associated infections
 Rotavirus gastroenteritis is a self-limited disease and only needs supportive
care.
 Treatment is not necessary for asymptomatic carriers of Clostridium difficile.
 For those who have mild symptoms, discontinuance of antibiotics alone
may result in resolution of symptoms.
 For those who have more severe diarrhea, oral metronidazole is the
preferred treatment.
 Oral vancomycin is reserved for treatment failure with metronidazole.
 Clinical improvement is usually seen within 2 days of initiating therapy, and
duration of treatment is usually 10 days.

27. Thank You