Meningitis (Neisseria)
Causative Organism: Neisseria meningitidis (gram-negative diplococci)
Mode of Transmission: Droplet contact
Virulence Factors: Capsule, endotoxin and IgA protease
Culture/Diagnosis: Gram stain/culture of CSF, blood, rapid antigenic tests, oxidase test, and PCR
Prevention: Conjugated vaccine; ciprofloxacin, rifampin, or ceftriaxone used to protect contacts
Treatment: Ceftriaxone, penicillin
Meningitis (Streptococcus)
Causative Organism: Streptococcus pneumoniae (small, gram-positive, flattened coccus)
Mode of Transmission: Droplet contact
Virulence Factors: Capsule, induction of apoptosis, hemolysin, and hydrogen peroxide production
Culture/Diagnosis: Gram stain/culture of CSF
Prevention: Two vaccines: Prevnar
(children and adults) and
Pneumovax (adults)
Treatment: Vancomycin + ceftriaxone or
cefotaxime;
resistant S. pneumoniae is categorized by the CDC as a Serious Threat
Meningitis (Haemophilus)
Causative Organism: Haemophilus influenzae (gram-negative coccobacillus)
Mode of Transmission: Droplet contact
Virulence Factors: Capsule
Culture/Diagnosis: Culture on chocolate agar
Prevention: Hib vaccine, ciprofloxacin, rifampin, or ceftriaxone
Treatment: ceftriaxone
Meningitis (Listeria)
Causative Organism: Listeria moncytogenes (gram-positive from coccobacilli to long filaments)
Mode of Transmission: Vehicle (food)
Virulence Factors: Intracellular growth
Culture/Diagnosis: cold enrichment, rapid methods
Prevention: cooking food, avoiding unpasteurized dairy products
Treatment: Ampicillin + gentamicin
Meningitis (Cryptococcus)
Causative Organism: Cryptococcus neoformans (yeast)
Mode of Transmission: Vehicle (air, dust)
Virulence Factors: Capsule, melanin production
Culture/Diagnosis: Negative staining, biochemical tests, DNA probes, cryptococcal antigen test
Prevention: N/A
Treatment: Amphotericin B and flucytosine, followed by fluconazole
Meningitis (Coccidioides)
Causative Organism: Coccidioides
Mode of Transmission: Vehicle (air, dust, and soil)
Virulence Factors: Granuloma (spherule) formation
Culture/Diagnosis: dentification of spherules, cultivation on Sabouraud’s agar
Prevention: Avoiding airborne endospores
Treatment: Fluconazole or amphotericin B
Meningitis (viruses)
Causative Organism: viruses
Mode of Transmission: Droplet contact
Virulence Factors: Lytic infection of host cells
Culture/Diagnosis: Initially, absence of bacteria/fungi/protozoa, followed by viral culture or antigen tests
Prevention: N/A
Treatment: Usually none (unless specific virus identified and specific antiviral exists)
Neonatal and Infant Meningitis (Streptococcus)
Causative Organism: Streptococcus agalactiae
Mode of Transmission: vertical (during birth)
Virulence Factors: Capsule
Culture/Diagnosis: Culture mother’s genital tract on blood agar; CSF culture of neonate
Prevention: Culture and treatment of mother
Treatment: Penicillin G plus aminoglycosides
Neonatal and Infant Meningitis ( E. coli, K1)
Causative Organism: Escherichia coli, strain K1 B G-
Mode of Transmission: Vertical (during birth)
Virulence Factors: N/A
Culture/Diagnosis: CSF Gram stain/culture
Prevention: N/A
Treatment: Ceftazidime or cefepime ± gentamicin
Neonatal and Infant Meningitis (Listeria)
Causative Organism: Listeria monoctogenes
Mode of Transmission: Vertical
Virulence Factors: Intracellular growth
Culture/Diagnosis: Cold enrichment, rapid methods
Prevention: Cooking food, avoiding unpasteurized dairy
products
Treatment: Ampicillin, trimethoprim-sulfamethoxazole
Neonatal and Infant Meningitis (Cronobacter)
Causative Organism: Cronobacter sakazakii
Mode of Transmission: Vehicle (baby formula)
Virulence Factors: Ability to survive dry conditions
Culture/Diagnosis:
Prevention: Chromogenic differential agar or rapid detection
kits
Treatment: Safe preparation and use of, or avoidance
of,
powdered formula
Primary Amoebic Meningoencephalitis
Causative Organism: Naegleria fowleri
Mode of Transmission: Vehicle (exposure while swimming in water)
Virulence Factors: Invasiveness
Culture/Diagnosis: Examination of CSF; brain imaging,
biopsy
Prevention: Limit warm freshwater or untreated tap water entering nasal passages
Treatment: Pentamidine, sulfadiazine
Granulomatous Amoebic Meningoencephalitis
Causative Organism: Acanthamoeba
Mode of Transmission: Direct contact
Virulence Factors: Invasiveness
Culture/Diagnosis: Examination of CSF; brain imaging, biopsy
Prevention: N/A
Treatment: Surgical excision of granulomas; pentamidine
Acute Encephalitis Disease (Arboviruses)
Causative Organisms: Arboviruses (West Nile virus, La Crosse
virus, Jamestown Canyon virus, St. Louis
encephalitis virus,
Powassan virus, Eastern equine encephalitis virus)
Mode of Transmission: Vector (arthropod bites)
Virulence Factors: Attachment, fusion, invasion capabilities
Culture/Diagnosis: History, rapid serological tests,
nucleic
acid amplification tests
Prevention: Insect control
Treatment: none
Acute Encephalitis Disease (Herpes Simplex)
Causative Organism: Herpes simplex 1 or 2
Mode of Transmission: Vertical or reactivation of latent
infection
Virulence Factors: N/A
Culture/Diagnosis: Clinical presentation, PCR, Ab tests,
growth
of virus in cell culture
Prevention: Maternal screening for HSV
Treatment: Acyclovir
Acute Encephalitis Disease (JC virus)
Causative Organism: JC virus
Mode of Transmission: Ubiquitous
Virulence Factors: N/A
Culture/Diagnosis: PCR of cerebrospinal fluid
Prevention: None
Treatment: No drugs proven effective; mefloquine and others have been used
Acute Encephalitis Disease (Postinfection)
Causative Organism: Postinfection encephalitis
Mode of Transmission: Sequelae of measles, other viral infections, and, occasionally, vaccination
Virulence Factors: N/A
Culture/Diagnosis: History of viral infection or vaccination
Prevention: N/A
Treatment: Steroids, anti-inflammatory agents
Subacute Encephalitis Disease (Toxoplasma)
Causative Organism: Toxoplasma gondii
Mode of Transmission: Vehicle (meat) or fecal–oral
Virulence Factors: Intracellular growth
Culture/Diagnosis: Serological detection of IgM, culture, histology
Prevention: Personal hygiene, food hygiene
Treatment: Pyrimethamine and/or leucovorin and/or sulfadiazine
Subacute Encephalitis Disease (sclerosing)
Causative Organism: Subacute sclerosing
panencephalitis
Mode of Transmission: Persistence of measles virus
Virulence Factors: Cell fusion, evasion of immune system
Culture/Diagnosis: EEGs, MRI, serology (Ab versus measles virus)
Prevention: None
Treatment: None
Subacute Encephalitis Disease (Prions)
Causative Organism: Prions
Mode of Transmission: CJD = direct/parenteral contact with infected tissue, or inherited vCJD = vehicle (meat, parenteral)
Virulence Factors: Avoidance of host immune response
Culture/Diagnosis: Biopsy, image of brain
Prevention: Avoiding infected meat or instruments; no prevention for inherited form
Treatment: None
Zika Virus Infection
Causative Organism: Zika virus
Mode of Transmission: Vertical, vector-borne, sexual
contact;
likely through blood transfusions (not yet confirmed)
Virulence Factors: Protein that reduces innate immune
response
Culture/Diagnosis: PCR testing
Prevention: Avoiding mosquitoes; no vaccine yet
Treatment: Supportive
Rabies Disease
Causative Organism: Rabies virus
Mode of Transmission: Parenteral (bite trauma), droplet contact
Virulence Factors: Envelope glycoprotein
Culture/Diagnosis: Direct fluorescent antibody test (DFA)
Prevention: Inactivated vaccine
Treatment: Postexposure passive and active immunization; induced coma and ventilator support if symptoms have begun
Poliomyelitis Disease
Causative Organism: Poliovirus
Mode of Transmission: Fecal-oral, vehicle
Virulence Factors: Attachment mechanisms
Culture/Diagnosis: Viral culture, serology
Prevention: Live attenuated (developing world);
inactivated
vaccine (developed world)
Treatment: None, palliative, supportive
Tetanus Disease
Causative Organism: Clostridium tentani
Mode of Transmission: Parenteral, direct contact
Virulence Factors: Tetanospasm exotoxin
Culture/Diagnosis: Symptomatic
Prevention: Tetanus toxoid immunization
Treatment: Combination of passive antitoxin and tetanus
toxoid
active immunization, metronidazole, and muscle relaxants; sedation
Botulism Disease
Causative Organism: Clostridium botulinum
Mode of Transmission: Vehicle (foodborne toxin, airborne organism), direct contact (wound), and parenteral (injection)
Virulence Factors: Botulinum exotoxin
Culture/Diagnosis: Culture of organism; demonstration of toxin
Prevention: Food hygiene; toxoid immunization available
for
laboratory professionals
Treatment: Antitoxin, penicillin G for wound botulism,
and
supportive care
African Sleeping Sickness Disease
Causative Organism: T rypanosoma brucei subspecies gambiense or rhodesiense
Mode of Transmission: Vector, vertical
Virulence Factors: Immune evasion by antigen shifting
Culture/Diagnosis: Microscopic examination of blood, CSF
Prevention: Vector control
Treatment: Suramin or pentamidine (early), eflornithine
or
melarsoprol (late)