Neisseria

Chapter 30

“Don’t eat chocolate agar!”

Neisseria

2 important species: Neisseria gonorrhoeae Neisseria meningitidis Gram -, diplococci

Figure 30-1 Virulence factors – Table 30-1

Gonorrhea

Primary site of infection Males – urethra (Fig. 30-2)

Purulent discharge, dysuria, 2-5 day incubation 95% of men show symptoms

Females – cervix Can progress to PID in 10-20% of women Vaginal discharge, dysuria, abdominal pain Only ~50% of women show symptoms

Boxes 30-2 and 30-4

Disseminated Gonococcal Infection

In a few persons, the organism gains access to the blood stream and spreads throughout the body. This serious complication is characterized by elevated temp., joint pain, multiple small abscesses in the skin, and sometimes infections of the joints, tendons, heart valves, and meninges Fig 30-3

Other N. gonorrhoeae Syndromes

Purulent conjunctivitis, particularly in newborns infected during vaginal delivery (ophthalmia neonatorum—Fig 30-4)

Meningitis

Site of infection Meninges

Symptoms Headache Fever Confused/Disoriented/Agitated May lead to neurologic damage, hearing

problems, and arthritis

Meningococcemia

Site of infection Blood stream

Symptoms Thrombosis of small blood vessels Multiple organ involvement Small skin lesions (Fig 30-5) Shock as a result of disseminated

intravascular coagulation with destruction of adrenal glands

Epidemiology of Gonococci

Gonorrhea occurs only in humans; there is no other reservoir Major reservoir is asymptomatically

infected person Second to chlamydia as most

commonly reported STD in US Rates in males and females are equal Highest in southeastern US

Epidemiology cont.

Occurs most often between ages of 15-24

Decreased between ’75-’98 but has leveled out since then; 310,000 new cases were reported in 2004 It is believed by officials that an accurate

measure would double this number

Epidemiology cont.

Women have a 50% chance of becoming infected per single exposure As many as half of infected women are

asymptomatic Men have approximately 20% chance

of becoming infected Most men (95%) are symptomatic

Epidemiology of Meningococci

Endemic throughout the world Epidemics commonly occur in developing

countries as a result of introducing a new virulent strain

Transmitted by respiratory droplets among people in prolonged close contact

Carriage is typically transient Humans are only natural carriers

Other Facts About Meningococcal

Total of 1254 cases of meningococcal disease were reported in the US in 2004 Most were meningitis

Mortality approaches 100% without treatment, but is less than 10% in patients who quickly receive appropriate antibiotic treatment

Laboratory Diagnosis-Gonorrhea

Gram stain is effective in men with purulent discharge

Not quite as effective in asymptomatic men

Difficult to use as proof of infection in women; depends on the skills of the microscopist Must be proven by culture

Laboratory Diagnosis-Meningitis

Easily seen by stain of cerebrospinal fluid (Fig 30-6)

Unlike most bacteremia, meningococcal bacteremia has enough cells in the blood to identify

Treatment Prevention and Control

Penicillin is no longer used for Gonorrhea due to resistance Beta-lactamase—plasmid transfer of genes Mutations in penicillin-binding proteins and cell

wall permeability Ciprofloxacin resistance is common in Asia,

the Pacific Islands, California, and in the male homosexual population in some US cities

Treatment Prevention and Control

N. meningitidis is susceptible to penicillin

Vaccine For Gonorrhea?

Multiple infections are still common Variability in POR proteins, LOS, and Pili

antigens make it difficult to create a vaccine There is antigenic diversity among strains Protection for infants against eye infections

1% silver nitrate, 1% tetracycline, or .5% erythromycin