The Epidemiology of Colonization

Abstract

Colonization is the presence of a microorganism in or on a host, with growth and multiplication but without any overt clinical expression or detected immune response in the host at the time it is isolated. Normal colonization in humans begins during the birth process and through subsequent contacts with the inanimate or animate environments until a delicately balanced "normal" flora is established; subsequently, the precise components of this flora evolve. This normal flora, such as coagulase-negative Staphylococcus or Staphylococcus aureus on the skin or Candida albicans in the gastrointestinal tract, vagina, or perineal area, can result in infection when normal body defenses are impaired through underlying disease, immunomodulating therapy, or the use of invasive devices, or when the delicate balance of the normal flora is altered through antimicrobial therapy. Many, if not most, hospital-acquired infections result directly or indirectly from patient colonization; studies have shown that hospitalized patients are colonized rapidly with hospital flora. Recognizing this reservoir of patients colonized with epidemiologically important pathogens in our hospitals and improving barrier precaution measures or altering host susceptibility will be necessary if we are to reduce the incidence of infections with these organisms.

Combined detection of mannanaemia and anti-mannan antibodies as a strategy for the diagnosis of systemic infection caused by pathogenic Candida species

“…In a pioneering study in 1971 on systemic candidosis in patients with acute leukaemia, the authors came to the following conclusion 'We recommend serial determination of anti-Candida agglutinating antibody titres in groups of patients known to have increased susceptibility to fungal infections as this is the most reliable means for diagnosing visceral candidiasis' [30]. Following the observation that an antibody response developed as candida colonisation in hospitalised patients increased [31,52], confidence in the specificity of these tests decreased. Despite several studies demonstrating the usefulness of anti-Candida antibody detection tests for diagnosis [53,54], these tests are seldom requested by physicians in clinical practice.…”

Nasopharyngeal colonization with methicillin-resistant staphylococcus aureus and mortality among patients in an intensive care unit

“…Will the results of this study be used as a rationale against the need for active surveillance cultures? It is a fact that the collection of these cultures increases laboratorial costs and the workload of professionals from infection control committees (8)(9) . However, we believe that a conclusive answer for the real need for surveillance cultures requires clarification of other factors.…”

“…In addition, colonized patients can spread this agent in ICUs, contributing to increased morbidity and mortality (8) . The identification and isolation of individuals infected by MRSA, even when these do not present signs of active infection, contribute to reduce the circulation of this agent and also its participation in the HAI etiology.…”

314 Healthcare-Associated Infections in Pediatrics

“…Endogenous infections usually occur as a result of healthcare-associated interventions (e.g., surgical procedures or the insertion of vascular catheters or other indwelling devices) [34], by colonization and subsequent infection with microorganisms from the hospital environment due to immunosuppression, or by normal flora altered through antimicrobial therapy [36]. Exogenous infections result from the transmission of organisms from the hospital environment [34].…”

“…CVC data was available for 580 (83%) primary BSIs and 75% of those were CVC-associated. In total, 27,279 blood samples were obtained for culture (median 62; range by year, 48-91 cultures per 1,000 patientdays), and 27 BSIs were confirmed per 1,000 blood cultures (range by year, [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36].…”