Microbiology for pharm d students

1. Fungi, Protozoa, and Parasites

2. Mycology
• the study of fungi, a group that includes the
mushrooms and yeasts. Many fungi are useful
in medicine and industry. Mycological
research has led to the development of such
antibiotic drugs as penicillin, streptomycin,
and tetracycline, as well as other drugs,
including statins

3. I. FUNGI (Mycology)
 Diverse group of heterotrophs.
– Many are ecologically important saprophytes (consume dead and
decaying matter)
– Others are parasites.
 Most are multicellular, but yeasts are unicellular.
 Most are aerobes or facultative anaerobes.
 Cell walls are made up of chitin (polysaccharide).
 Over 100,000 fungal species identified. Only about
100 are human or animal pathogens.
– Most human fungal infections are nosocomial and/or occur in
immunocompromised individuals (opportunistic infections).
 Fungal diseases in plants cause over 1 billion
dollars/year in losses.

4. CHARACTERISTICS OF FUNGI
1. Yeasts
 Unicellular fungi, nonfilamentous, typically oval or spherical cells.
Reproduce by mitosis:
– Fission yeasts: Divide evenly to produce two new cells (Schizosaccharomyces).
– Budding yeasts: Divide unevenly by budding (Saccharomyces).
Budding yeasts can form pseudohypha, a short chain of undetached cells.
Candida albicans invade tissues through pseudohyphae.
 Yeasts are facultative anaerobes, which allows them to grow in a variety
of environments.
– When oxygen is available, they carry out aerobic respiration.
– When oxygen is not available, they ferment carbohydrates to produce ethanol and carbon
dioxide.

5. CHARACTERISTICS OF FUNGI (Continued)
2. Molds and Fleshy Fungi
Multicellular, filamentous fungi.
Identified by physical appearance, colony characteristics,
and reproductive spores.
– Thallus: Body of a mold or fleshy fungus. Consists of many hyphae.
– Hyphae (Sing: Hypha): Long filaments of cells joined together.
Septate hyphae: Cells are divided by cross-walls (septa).
Coenocytic (Aseptate) hyphae: Long, continuous cells that are
not divided by septa.
Hyphae grow by elongating at the tips.
Each part of a hypha is capable of growth.
Vegetative Hypha: Portion that obtains nutrients.
Reproductive or Aerial Hypha: Portion connected with
reproduction.
– Mycelium: Large, visible, filamentous mass made up of many
hyphae.

6. Characteristics of Fungal Hyphae:
Septate versus Coenocytic

7. Mycelium: Large, Visible Mass of Hyphae

8. CHARACTERISTICS OF FUNGI (Continued)
Dimorphic Fungi
Can exist as both multicellular fungi (molds) and yeasts.
Many pathogenic species.
– Mold form produces aerial and vegetative hyphae.
– Yeast form reproduces by budding.
Dimorphism in pathogenic fungi typically depends on
temperature:
– At 37oC: Yeast form.
– At 25oC: Mold form.
Dimorphism in nonpathogenic fungi may depend on other
factors: Carbon dioxide concentration.

9. LIFE CYCLE OF FUNGI
Filamentous fungi can reproduce asexually by
fragmentation of their hyphae.
Fungal spores are formed from aerial hyphae and are
used for both sexual and asexual reproduction.
1. Asexual spores: Formed by the aerial hyphae of one organism.
New organisms are identical to parent.
Conidiospore: Unicellular or multicellular spore that is not
enclosed in a sac.
Chlamydospore: Thick-walled spore formed within a hyphal
segment.
Sporangiospore: Asexual spore formed within a sac
(sporangium).
2. Sexual spores: Formed by the fusion of nuclei from two opposite
mating strains of the same species. New organisms are different
from both parents.

10. IMPORTANT DIVISIONS OF FUNGI
1. Deuteromycota
Not known to produce sexual spores.
Reproduce asexually.
 Catch-all category for unclassified fungi:
– Pneumocystis carinii: Causes pneumonia in AIDS
patients. Leading cause of death in AIDS patients.
Originally classified as a protozoan.
– Candida albicans: Causes yeast infections of vagina in
women. Opportunistic infections of mucous
membranes in AIDS patients.

11. IMPORTANT DIVISIONS OF FUNGI
2. Zygomycota (Conjugation Fungi)
Also known as bread molds.
Saprophytic molds with coenocytic hyphae (lack septa).
Asexual Reproduction: Used most of the time.
Sporangiospore: Asexual spore enclosed within a
sporangium or sac at the end on an aerial hypha.
Sexual Reproduction: Occurs through conjugation, the
joining of hypha of two different strains (plus and minus).
Zygospores: Sexual spores which are enclosed in a thick,
resistant wall.
 Generally not pathogens.
– Rhizopus nigricans: Common black bread mold. May cause
opportunistic infections in diabetes patients

12. Life Cycle of a Zygomycete: Black Bread Mold (Rhizopus)
Reproduces Asexually and Sexually

13. Reproductive Structures of Zygomycete (Rhizopus)
Sporangia (asexual) and Zygospore (sexual)

14. IMPORTANT DIVISIONS OF FUNGI
3. Ascomycota (Sac Fungi)
Molds with septate hyphae and some yeasts.
Asexual Reproduction: Conidiospores not enclosed in a
sac. Become airborne easily. Form chains (broom-like
structures).
 Sexual Reproduction: Ascospores enclosed in a sac-like
structure (ascus).
Include common antibiotic producing fungi and yeasts, and
several human pathogens.
– Penicillium notatum (Produces penicillin)
– Saccharomyces (Brewer’s yeast)
– Trychophyton (Athlete’s foot)
– Aspergillus (Carcinogenic aflatoxin in peanuts),
– Blastomyces (Respiratory infections)
– Histoplasma capsulatum (Respiratory and systemic infections)

15. Life Cycle of Eupenicillium (Ascomycete)
Reproduces Asexually and Sexually

16. Severe nail infection with Trichophyton rubrum in
a 37-year-old male AIDS patient.
Source: Intern. J. Dermatol. 31(1992): 453.

17. Disseminated Histoplasma capsulatum, skin infection.
Source: Microbiology Perspectives, 1999.

18. IMPORTANT DIVISIONS OF FUNGI
4. Basidiomycota (Club Fungi)
Have septate hyphae.
Include mushrooms, toadstools, rusts, and smuts.
Sexual Reproduction: Produce basidiospores: Spores
formed externally on a club shaped sexual structure or base
called basidium.
 Asexual Reproduction: Through hyphae.
 Examples:
– Cryptococcus: Causes opportunistic respiratory and CNS infections in
AIDS patients.

19. Life Cycle of a Basidiomycete
Mushrooms are Produced Sexually

20. NUTRITIONAL ADAPTATIONS OF FUNGI
Fungi absorb their food, rather than ingesting it.
Fungi grow better at a pH of 5, which is too acidic for most
bacteria.
Almost all molds are aerobic. Most yeasts are facultative
anaerobes.
Fungi are more resistant to high osmotic pressure than
bacteria.
Fungi can grow on substances with very low moisture.
Fungi require less nitrogen than bacteria to grow.

21. FUNGAL DISEASES
Mycosis: Any fungal disease. Tend to be chronic because fungi
grow slowly.
Mycoses are classified into the following categories:
I. Systemic mycoses: Fungal infections deep within the body.
Can affect a number if tissues and organs.
Usually caused by fungi that live in the soil and are inhaled.
Not contagious.
Examples:
– Histoplasmosis (Histoplasma capsulatum): Initial infection in lungs.

22. Systemic Mycosis: Histoplasmosis
Disseminated Histoplasma capsulatum, lung infection.
Source: Microbiology Perspectives, 1999.

23. FUNGAL DISEASES (Continued)
II. Cutaneous mycoses: Fungal infections of the skin, hair, and
nails.
Secrete keratinase, an enzyme that degrades keratin.
Infection is transmitted by direct contact or contact with
infected hair (hair salon) or cells (nail files, shower floors).
Examples:
– Ringworm (Tinea capitis and T. corporis)
– Athlete’s foot (Tinea pedis)
– Jock itch (Tinea cruris)

24. Cutaneous Mycosis
Ringworm skin infection: Tinea corporis
Source: Microbiology Perspectives, 1999

25. Cutaneous Mycosis
Candida albicans infection of the nails.
Source: Microbiology Perspectives, 1999.

26. FUNGAL DISEASES (Continued)
III. Subcutaneous mycoses: Fungal infections beneath the skin.
Caused by saprophytic fungi that live in soil or on vegetation.
Infection occurs by implantation of spores or mycelial
fragments into a skin wound.
Can spread to lymph vessels.
IV. Superficial mycoses: Infections of hair shafts and superficial
epidermal cells. Prevalent in tropical climates.

27. FUNGAL DISEASES (Continued)
Opportunistic mycoses: Caused by organisms that are
generally harmless unless individual has weakened
defenses:
– AIDS and cancer patients
– Individuals treated with broad spectrum antibiotics
– Very old or very young individuals (newborns).
 Examples:
– Aspergillosis: Inhalation of Aspergillus spores.
– Yeast Infections or Candidiasis: Caused mainly by Candida albicans.
Part of normal mouth, esophagus, and vaginal flora.

28. ECONOMIC IMPORTANCE OF FUNGI
25-50% of harvested fruits and vegetables are damaged by
fungi.
Fungal infections of plants are commonly called rots, rusts,
blights, wilts, and smuts.
– Phytophthora infestans: Caused great potato famine in mid-1800s.
Over 1 million people died from starvation in Ireland. Many
immigrated to the U.S.
 Beneficial fungi:
– Candida oleophila: Prevents fungal growth on harvested fruits.
– Saccharomyces cerevisiae: Used to make bread and wine.
– Genetically engineered yeast strains are used to make proteins
(Hepatitis B vaccine).
– Taxomyces: Produces anticancer drug taxol.
– Trichoderma: Produces cellulase. Used to make fruit juice.

29. V. PROTOZOA
Unicellular, chemoheterotrophic, eukaryotic organisms of
kingdom Protista (3-2000 mm).
Protozoan means “first animal”.
20,000 species, only a few are pathogens.
Most are free-living organisms that inhabit water and soil.
Some live in association with other organisms as parasites or
symbionts.
Reproduce asexually by fission, budding, or schizogony.
Some exhibit sexual reproduction (e.g.: Paramecium).
Trophozoite: Vegetative stage which feeds upon bacteria
and particulate nutrients.
Cyst: Some protozoa produce a protective capsule under
adverse conditions (toxins, scarce water, food, or oxygen).

30. V. PROTOZOA (Continued)
Nutrition
 Most are heterotrophic aerobes. Intestinal protozoa can
grow anaerobically.
Some ingest whole algae, yeast, bacteria, or smaller
protozoans. Others live on dead and decaying matter.
Parasitic protozoa break down and absorb nutrients from
their hosts.
Some transport food across the membrane.
Others have a protective covering (pellicle) and required
specialized structures to take in food.
– Ciliates take in food through a cytostome.
Digestion takes place in vacuoles.
Waste may be eliminated through plasma membrane or an
anal pore.

31. Medically Important Protozoa
1. Amoeboflagellates (Phylum Sarcomastigophora)
Move using pseudopods (false feet) or flagella.
A. Amoebas (Subphylum Sarcodina)
Move by extending blunt, lobelike projections
(pseudopods).
Amoebas engulf food with pseudopods and phagocytize it.
Several species cause amoebic dysenteries of varying
degrees of severity.
– Entamoeba hystolytica: Feeds on red blood cells. Produces
dysentery and extraintestinal cysts.
– Dientamoeba fragilis: Found in 4% of humans. Usually commensal.
Can cause chronic, mild diarrhea.
Other diseases include:
– Meningoencephalitis: Caused by Naegleria fowleri. Penetrate
nasal mucosa of swimmers in warm waters. Mortality rate almost
100%.
– Keratitis: Caused by Acanthamoeba. Can cause blindness.
Associated with use of contact lenses.

32. B. Flagellates (Subphylum Mastigophora)
Move by one or more whiplike flagella. Some parasitic
flagellates have up to eight flagella.
Most are spindle shaped with flagella projecting from
anterior end.
Outer membrane is a tough pellicle. Food is ingested
through an oral groove or cytosotome.
 Important pathogens:
– Trichomonas vaginalis: Causes genital and urinary infections. Has
undulating membrane. Lacks a cyst stage. Transmitted sexually or
by fomites.
– Giardia lamblia: Causes a persistent intestinal infection (giardiasis)
with diarrhea, nausea, flatulence, and cramps. In U.S. most
common cause of waterborne diarrhea. About 7% of U.S.
population are healthy carriers.
– Trypanosoma brucei gambiense: Hemoflagellate (blood parasite).
Causes African sleeping sickness.
– Trypanosoma cruzi: Hemoflagellate that causes Chaga’s disease, a
cardiovascular disease common in Texas and Latin America.

34. Medically Important Protozoa (Continued)
2. Apicomplexans (Phylum Apicomplexa)
Not motile in their mature form.
Obligate intracellular parasites.
Have specialized organelles at tip (apex) of cells that
penetrate host tissues.
Complex life cycles. May have more than one host.
Definitive host: Harbors sexually reproducing form.
Intermediate host: In which asexual reproduction occurs.

35. Medically Important Protozoa (Continued)
2. Apicomplexans (Phylum Apicomplexa)
Important pathogens:
– Plasmodium vivax and falciparum: Cause malaria in humans
(intermediate host).
Initially treated with quinine, drug resistance is a major problem
today.
Major cause of worldwide mortality: Kill 3 million people/year and
infect 500 million.
Transmitted by Anopheles mosquito (definitive host).
DDT was used extensively in 1960s in an attempt to eradicate the
mosquito vector.
Successful vaccine not available yet.

37. Life Cycle of Plasmodium spp. the
Infectious Agent of Malaria

38. Chronic Disease
Chronic
Asymptomatic
Infection
Placental
Malaria
Anemia
Infection
During
Pregnancy
Developmental
Disorders;
Transfusions;
Death
Low
Birth weight
Increased
Infant
Mortality
Acute Disease
Non-severe
Acute Febrile
disease
Severe
malaria e.g.
Cerebral
Malaria
Death
CLINICAL PICTURE

39. • Severe malaria is defined as symptomatic malaria in a patient with
P. falciparum with one or more of the following complications:
– Cerebral malaria (unreadable coma not attributable to other causes).
– Generalized convulsions (> 2 episodes within 24 hours)
– Severe normocytic anaemia (Ht<15% or Hb < 5 g/dl)
– Hypoglycemia (blood glucose < 2.2 mmol/l or 40 mg/dl )
– Metabolic acidosis with respiratory distress (arterial pH < 7.35 or bicarbonate < 15 mmol/l)
– Fluid and electrolyte disturbances
– Acute renal failure (urine <400 ml/24 h in adults; 12 ml/kg/24 h in children)
– Acute pulmonary edema and adult respiratory distress syndrome
– Abnormal bleeding
– Jaundice
– Haemoglobinuria
– Circulatory collapse, shock, septicaema (algid malaria)
– Hyperparasitaemia (>10% in non-immune; >20% in semi-immune)

40. Malarial Paroxysm
cold stage
•feeling of intense cold
•vigorous shivering
•lasts 15-60 minutes
hot stage
•intense heat
•dry burning skin
•throbbing headache
•lasts 2-6 hours
sweating stage
•profuse sweating
•declining temperature
•exhausted and weak → sleep
•lasts 2-4 hours

41. The two methods common in use:
1: Light microscopy
2: Rapid diagnostic tests
(RDTs).
Common methods for parasitological diagnosis of malaria

42. Microscopy is the gold standard for
diagnosis of malaria
• Parasite density
• Species diagnosis
• Monitoring
response to
treatment

43. CCMOVBD
Plasmodium falciparum CCMOVBD
Plasmodium vivax
CCMOVBD
Plasmodium malariae Malaria Tutorials, Wellcome Trust Plasmodium ovale
Laboratory diagnosis of malaria

44. ACTION OF ANTIMALARIAL DRUG IN THE DIFFERENT LIFE
STAGES OF THE MALARIA PARASITE
Wellcome Trust (Modified)
Tissue Schizontocides
•Primaquine
•Pyrimethamine
•Tetracycline
•Proguanil
Anti-relapse (P.vivax)
•primaquine
Blood Schizontocides
•Chloroquine
•Sulfadoxine/Pyrimethamine
•Quinine
•Artemisinins
Gametocyide
Primaquine
Sporontocides
•Primaquine
•Pyrimethamine
•Proguanil

45. Medically Important Protozoa (Continued)
2. Apicomplexans (Phylum Apicomplexa)
Important pathogens:
– Toxoplasma gondii: Causes toxoplasmosis in humans. Causes
blindness and lymphatic infections in adults. Dangerous to pregnant
women, causes severe neurological defects in unborn children. Cats
are part of life cycle, oocysts excreted in feces. Contact with infected
feces or meat are means of transmission.
– Cryptosporidium: Causes respiratory and gallbladder infections in
immunosuppressed individuals. Found in intestines of mammals and
water. Major cause of death in AIDS patients.
– Cyclospora cayetensis: New parasite (1996) caused diarrhea
associated with raspberries.

46. Medically Important Protozoa (Continued)
3. Ciliates (Phylum Ciliophora)
Move and obtain food using cilia.
Only known human pathogen is Balantidium coli, which
causes a severe intestinal infection in pigs and humans.
4. Microsporans (Phylum Mycrospora)
Obligate intracellular parasites, lack mitochondria and
microtubules.
Discovered in 1984 to cause chronic diarrhea and
conjunctivitis, mainly in AIDS patients.

47. Paramecium caudatum is a Ciliated Protozoan
Conjugation Between Opposite Mating Strains