32. Outcomes of i nfection p rocess Hospitalization Infection Asymptomatic i nfection Mortality Disease Advanced i llness, c hronic i nfections and s equelae Acute s ymptomatic i llness: s everity and d ebilitation Exposure Sensitive p opulations
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37. Acute and c hronic o utcomes a ssociated with m icrobial i nfections
73. Common Causes of Nosocomial Infections Percentage of Total Infections Percentage Resistant to Antibiotics Coagulase-negative staphylococci 25% 89% S. a ureus ( MRSA) 16% 80% Enterococcus (vancomycin-res.) 10% 29% Gram-negative rods 23% 5-32% C. difficile 13% None
134. Entamoeba histolytica mature cysts quadrinucleate or mature cysts – diagnostic in feces
135. Entamoeba histolytica pathology 3. EXTRA-INTESTINAL LESIONS occur in 3 ECTOPIC SITES A. HEPATIC AMEBIASIS Trophozoites in submucosa are carried by hepatic portal vein to the liver -> abscess B. PULMONARY AMEBIASIS following l iver abscess rupture C. CEREBRAL AMEBIASIS Trophozoites in bloodstream
136. 2 Groups of Parasitic Amebae ____________________parasites – can only exist as parasites - amebae in the family Entamoebidae - occur in the digestive tracts of vertebrates ____________________parasites – free-living soil and water amebae that can become parasitic if they enter vertebrate tissues
137. Entamoeba histolytica pathology 1. COLONIZATION OF THE LARGE INTESTINE flask-shaped lesions: proteolytic enzymes : Symptoms: Ulcers may form sinuses and extend into the submucosa
138. Liver abscess Diagram of pathology from text on page 112 Shows movement of trophozoites from large intestine to lungs via hepatic portal vein
139. Pathology of Ascaris lumbricoides Roundworm, 1 billion patients infected worldwide, larval migration into systemic circulation -> hepatic abscess, eosinophilic pneumonitis. Adults in large numbers -> intestinal obstruction
140. Pathology of Ascaris lumbricoides Larvae cause problems in the lungs when they break through the lung capillaries to enter the respiratory tree. S mall hemorrhages , inflammatory response -> pneumonia-like symptoms The more eggs ingested, the more migrating larvae, the greater the pathology. larva Inflammatory cells
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142. Pathology of Enterobius vermicularis Pinworms do not invade any tissue , live intraluminally. Nightly egg deposition on the perirectal mucosa -> irritation of the anal region , itching, possible s econdary bacterial infection in scratched .
231. Parasitic inf. - Naegleria fowleri After entering the nose and nasal cavities, the trophozoites actively migrate to the brain and cause purulent meningoencephalitis - abscess. Symptoms : headache, fever, neck rigidity, and mental confusion followed by coma and death
232. Facultative Amebae Facultative amebae are normal inhabitants of soil and water where they feed on bacteria. A few members have the ability to become parasitic when an opportunity to enter a vertebrate exists. Three are able to infect humans: Naegleria fowleri This ameba is responsible for over 200 cases of _____________________________________________________ During 1989-2000, CDC documented 24 fatal cases of PAM in the United States. Only 7 cases were successfully treated; all others were fatal!
256. Ascarid Nematodes – Chapter 26 Ascaris lumbricoides Common parasite of humans. Disease is called ______________________________ Cosmopolitan in distribution. - flourishes in warm, moist climates where the eggs may remain viable in warm soil for many years. - use of ___________________________ to fertilize vegetables is common source of infection. - Children are most likely to become infected by ingesting eggs by eating dirt or placing soiled fingers or toys into the mouth.
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266. THE MOST IMPORTANT RISK FACTORS 7. Indwelling catethers 8. Major surgery 9. Organ transplantation 10. Neonates 11. Severity of any illness 12. Intravenous drug addicts
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274. The most frequent syndromes are: - aspergilloma - invasive aspergillosis (high mortality rate) Treatment : amphotericin B, itraconazole, flucytosine and surgery Prevention : avoid exposure to conidia (new buildings in the hospital!)
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276. Major clinical syndrome is: Rhinocerebral mucormycosis (infection of nasal passages, sinuses, eyes, cranial bones and brain) Treatment : surgery and amphotericin B Prognosis : very poor
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Editor's Notes
Figure 3. Initial Radiograph of the Lung and Lung-Tissue Sample from Patient 3. The radiograph (Panel A) shows bilateral alveolar opacities in the base of both lungs that progressed and became confluent. The specimen (Panel B, hematoxylin and eosin) shows necrosis of bronchiolar walls (top arrow), a neutrophilic infiltrate (middle arrow), and diffuse alveolar damage with prominent hyaline membranes (bottom arrow). Bacterial cultures were negative on admission, and no evidence of bacterial infection of the lungs was found. The patient ultimately died.
Yeasts are unicellular organisms, reproducing by budding and division; molds are multicellular organisms growing in filaments called hyphae, forming mycelium and reproducing by conidia and spores. Both yeasts and molds have sexual and asexual reproduction. Rare fungi have other forms (cysts, spherulas). Fungi have a rigid cell wall with mannans, glucans and chitin in it, and with ergosterol in the cell membrane.
1. Affects stratum corneum only; Malassezia furfur rarely causes opportunistic fungemia 2. Affects superficial keratinized tissue only (about 40 related fungi) 3. Fungi from soil or vegetation, reach subcutaneous tissue by traumatic inoculation; rarely cause systemic disease.
4. Fungi geographically restricted to specific endemic areas. They are primary pathogens (true pathogenic fungi), living in soil mixed with guano ( H. capsulatum, C. immitis ), or not clearly defined soil ( B. dermatitidis , P. brasiliensis ). They cause pneumonia and systemic disease in a previously healthy persons.
“ Endogenous” means that the fungus is a part of a normal human flora. “Exogenous”(see next slide) means that the fungus does not normaly live in/on human body, although it can transiently contaminate human body surfaces (especially respiratory tract). P.carinii is most probably a part of normal flora of lungs of many mammals, including humans.
Some of many other opportunistic fungi are: Penicillium marneffei , Fusarium, Bipolaris, Exophiala, Scedosporium, Sporothrix, Pseudallescheria. True pathogenic (endemic) fungi cause more severe infections in compromised host than in otherwise healthy people. If a patient, undergoing therapy which will compromise him/her, was exposed, he/she has to take fluconazole for the reactivation prevention.
As Candida is present in practically all humans, it has many opportunities to cause endogenous infections in compromised host - so, Candida infections are the most frequent opportunistic fungal infections. Other Candida species are: C.tropicalis, C.krusei, C.parapsilosis, C.glabrata, C.gullermondii, C.lusitaniae, C.kefyr and many more.
If normal bacterial flora is disturbed by antimicrobial therapy, then Candida overgrowths on mucosal surfaces, and with its pseudohyphae internalizes (translocates) itself to deeper layers and causes mucosal infections. The same happens if skin and mucous membranes integrity is broken.
Neutrophil leukocytes are probably responsible for resistance to invasive candidiasis, and CD4 T-cells are responsible for resistance to mucocutaneous candidiasis. If neutrophil number or function is disturbed, after translocation, Candida goes to lymphatic and blood, spreading throughout the body and causing infection in virtually all organs.
1. The most profound neutropenia (less than 100 neutrophils/L) is seen in bone marrow and hematopoietic stem cells transplant patients, but occurs also in patients with malignancies treated with intensive chemotherapy. 2. In diabetic patients, fusion of lysosome in phagocytes is greatly impaired. 3.,4. CD4 T-cells defects are important risk factors.
Most cases of candidemia in surgical patients end this way. C.albicans is found in over 75% in blood culture of non-neutropenic and non-cancer patients, while other species are found in more than 50% of neutropenic and cancer patients.
The most frequent organs involved are kidney, skin (maculonodular lesions), eye, heart, liver, meninges. Prevention of candida infections in severely immunocompromised patient can be done by use of peroral fluconazole (azole antifungal drug) during deepest immunosupression
P.carinii is present worldwide and seroepidemiological studies show that most humans are infected in early childhood. Natural reservoir, the source and mode of transmission are not known, possibly P.carinii spreads by aerosols.
Main risk factors are AIDS, transplantation, corticosteroid and antineoplastic therapy. About 20% of AIDS patients will develop P.carinii pneumonia despite prophylaxis, if CD4 count is >100 mm 3 . Diagnosis is made from bronchoalveolar fluid, induced sputum or lung biopsy - smears are stained with special stains, and the presence of cysts and trophozoits is diagnostic. P.carinii has not yet been isolated.
Cryptococci are found in large numbers in dry pigeon feces. In macrophages Cryptococci can survive and grow easily.
Most frequent species causing infections in compromised patients are: A.fumigatus, A.flavus, A.niger, A.terreus , A.nidulans and many other species. Especially abundant are aspergilli conidia when buildings are done and various dusts are spread around.
Aspergilloma is formed when conidia are inhaled in a preexisting lung cavity (tuberculosis, emphysema); if there is not a cavity, aspergilli develop in lung tissue causing invasive infection (spreading through the tissue and involving blood vessels); then spread can occur to other organs. Diagnosis of aspergilloma is radiological (CT scan); invasive aspergillosis can be diagnosed from respiratory secretions or lung biopsy; test for circulating galactomannan is also diagnostic
Most frequent genera in the class Zygomycetes, causing disease in compromised host, are: rhisopus, rhizomucor, absidia, mucor, cunningamella.
Pulmonary infection can also occur, with very high mortality rate. Diagnosis is made by direct smear and by isolation of molds from respiratory secretions or biopsy specimens.
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