Colonization vs Infection Colonization • The presence of microorganisms in or on a host with growth and multiplication but without tissue invasion or damage • Understanding this concept is essential in the planning and implantation of epidemiological studies in a healthcare infection prevention and control program Infection v. Colonization • Confusing colonization with infection can lead to spurious associations that may lead to expensive, ineffective, and time‐ consuming interventions Multi Drug‐Resistant Organisms Management in Long Term Care • Colonization may become infection when changes in the host Facilities Workshop occur Louisiana Office of Public Health Healthcare‐Associated Infections Program Objectives Colonization: Definition By the end of the presentation, attendees will be able to: • Colonization: presence of a microorganism on/in a host, with • Define colonization growth and multiplication of the organism, but without • Differentiate colonization from infections interaction between host and organism (no clinical expression, no immune response). • Apply appropriate laboratory test by common LTC infectious • agents Carrier: individual which is colonized + more • • Understand the necessity of communicating infectious status Subclinical or unapparent infection: presence of upon patient transfer microorganism and interaction between host and microorganism (sub clinical response, immune response). Often the term colonization is applied for relationship host‐ agent in which the immune response is difficult to elicit. • Contamination: Presence of a microorganism on a body surface or an inanimate object. 1 Colonization vs Infection Spectrum: No Exposure ‐ Exposure ‐ Colonization ‐ Carrier Infection ‐ Disease A carrier is an individual that harbors a specific microorganism Host + Infectious agent What is “Exposed” ? in the absence of discernible clinical disease and serve as a No foothold: Exposed Means of transmission: potential source of infection. A carrier may be an individual Foothold, no reaction Being in the same room as an who is: Colonization infectious tuberculous patient Carrier or with a person with HIV • colonized Foothold: epithelial attachment Specific information: • infected and asymptomatic Multiplication: Infection Eating a meal or eating the contaminated food item? • in incubation period before disease Direct cytotoxicity Exposure definition relies on • convalescent from acute disease Toxins information that may not be all Tissue disruption known. The carrier status may be short or lengthy. Tissue injury Dissemination Think about carrier as •Source Asymptomatic •Explanation for person who Symptomatic apparently is not infected Flora at Colonization Sites Infection CONJUNCTIVA OROPHARYNX Staphylococci NASOPHARYNX Streptococcus viridans group Corynebacteria Staphylococci • The replication of organisms in host tissue which may cause Streptococcus pyogenes Haemophilus disease Streptococcus pneumoniae Streptococci Moraxella catarrhalis Staphylococci SKIN • Infection: defines the entrance and development of an Neisseria spp Moraxella catarrhalis Staphylococci infectious agent in a human or animal body, whether or not it Neisseria spp Haemophilus spp develops into a disease Corynebacteria Corynebacterium spp Propionibacteria • Caused by an infectious agent: all micro‐ or macro‐organisms Haemophilus spp UPPER INTESTINE Streptococci Candida capable of producing an infection or an infectious disease Anaerobes: Bacteroides Malassezia furfur Candida albicans Lactobacillus spp • Infectious disease: an illness caused by a specific infectious Candida spp agent or its toxic product that results from transmission of GENITOURINARY TRACT that agent or its product from an infected person, animal, or Staphylococci, Streptococci LOWER INTESTINE reservoir to a susceptible host Enterococci Aerobic G- bacilli: E.coli, Klebs Lactobacillus spp, Corynebacterium Enterobacter, Proteus, Serratia Neisseria spp, Anaerobes Providencia, Bacteroides, Anaerobic Candida albicans Enterococci, Streptococci, Candida 2 Colonization vs Infection Skin Hand Flora RESIDENT FLORA Colonization Protects the Host • Survives on the skin more than 24 hours Normal flora protects against infectious diseases originating at mucous membranes. • Not easily removed, hours of scrubbing There are several mechanisms for protection: • Complete stelirization ‐ Non specific stimulation of immune responsiveness impossible TRANSIENT FLORA ‐ Specific cross reactive immunization • Low virulence • Survive on skin less than 24 hours ‐ Competitive bacterial interference • Staphylococci, diphteroides,• Easily removed with soap and water • mostly Gram + , • Acquired during contacts with • very few Gram ‐ contaminated areas mouth, nose, perineal area, genitals, anal area, Germ free animals reared in good health succumb rapidly from catheter, bedpan, urinal, patient care overwhelming infection when transferred with normal healthy casual contact animals • May have high virulence Number of bacteria to colonize gut • Enterobacteria, Gram ‐ bacilli, Normal animal, 10,000,000 Pseudomonas... Germ free animal, 100 Shifts in Colonization Flora Clinical Infection Clinical infection: Clinical infection may result in signs and symptoms. Some of these may be less obvious or very • General shift towards Gram‐negative flora in hospitals, LTCF and minor. At the end of the spectrum is the individual with other health care facilities no sign, no symptoms who has a asymptomatic infection or subclinical infection. • Modification of the skin environment due to skin changes still poorly understood • Invasive procedures provides portal of entry to different flora Asymptomatic infection does not mean that “all is quiet”. It may cover some very active processes as in the • Antibiotic therapy: asymptomatic phase of HIV infection, tuberculosis • In a study of patients on ampicillin long term Rx, 90% colonized by infection, hepatitis B carrier state. ampicillin‐resistant Enterobacteriae, controls only 10% 3 Colonization vs Infection True Infection NOT Colonization Sufficient Time to Develop Infection • Infections are accompanied by signs and • diseases with specific incubation period: stay symptoms: in hospital incubation period • fever, malaise • in localized infections: swelling due to • numerous infections do not have well set inflammation, heat, pain, erythema (tumor, dolor, incubation periods (for example, staphylococci, rubor, calor) E.coli infections) • Use definitions which establish minimum ‐ these infections rarely develop in less than characteristics for infection 2 days • NHSN criterion: Infection present after the 3rd 1 • Remember: Immunocompromised patients do hospital day (day of hospital admission is day not show signs of infection as normal patients. 3 1). Neutropenic patients ( 500 neutrophils /mm3) show no pyuria, no purulent sputum, little infiltrate and no large consolidation on chest X‐ray NO Infection at Time of Admission Methicillin‐Resistant • establish prior negativity Staphylococcus aureus (MRSA) • check history, symptoms and signs Colonization Infection • Approximately 30% of the • Occurs when a bacterial • documented at time of admission, lab tests population is colonized & chest X‐rays done strain undergoes with MRSA uncontrolled growth ‐normal physical examination • Organism lives on the skin • Can be localized to a ‐absence of signs and symptoms for long periods of time specific area such as a generally in warm, damp, ‐normal chest X‐ray wound or spread dark areas of the body 2Excluded: ‐negative culture or lack of culture through the bloodstream •Transplacental • Nose infections Example: If urine cultures are collected at • Throat (bacteremia) •Reactivation of old day 7 of hospitalization and none • Armpits infections (ex Shingles) was collected before, it implies that no •Infections considered signs of infection were present in urine • “South of the border” extensions of infections before present at admission 4 Colonization vs Infection Vancomycin‐resistant Clostridium difficile (CDIFF) Enterococci (VRE) Colonization Infection Colonization Infection • Asymptomatic • Presence of diarrheal • Acquired by susceptible • Weakened hosts have an • CDIFF is detected in the absence of symptoms of symptoms (3+ unformed hosts in an environment increased likelihood of infection stools in 24h) with a high rate of developing infection • The number of colonized • patient colonization with following colonization patients is higher than Stool tests positive for symptomatic CDI cases among CDIFF toxins or VRE, e.g. intensive care • PCR is used to detect hospital patients • Detection of toxigenic units, oncology units infections and outbreaks • Absence of diarrhea without CDIFF or colonoscopic histopathologic • Can lead to infection findings of • Colonoscopic findings pseudomembranous colitis demonstrating ulcerative depending on the health and colitis of the patient • Detection of CDIFF or • Presence of CDIFF toxins No tests of cure!!!! Carbapenem‐resistant Urinary Tract Infections Enterobacteriacea (CRE) Colonization Infection • The prevalence of asymptomatic bacteriuria (ASB), bacterial • Organism can be found on • Cause infections when they colonization of the urinary tract without local signs or symptoms of the body but is not causing enter the body through infection, ranges from 23‐50% in non‐catheterized NH/SNF residents any symptoms or disease medical devices like central to 100% among those with long‐term urinary catheters. • Strains can go on to cause lines,