Micro Made Simple Chapter 8.gram Negative Bacteria

Front 1

The only pathogenic gram-negative cocci?

Back 1

Neisseria. They are diplococci

Each coccus is shaped like a kidney bean. and a pair of cocci sticks together with their concave sides facing each other, almost making the diplococcus look like a small doughnut.

Front 2

What two species of Neisseria cause human disease?

Back 2

Neisseria meningitidis and Neisseria gonorrhoeae.

Front 3

What bacteria might form a gram-negative doughnut shaped diplococcus?

Back 3

Neisseria

Front 4

Neisseria meningitidis

Back 4

This kidney bean drinks coffee and becomes nervous and irritable (CNS irritation--meningitis)

Front 5

Neisseria gonorrhoeae

Back 5

(is a pervert) and has a centerfold pinup. He likes to hang out on sexual organs and swim in "sexual fluids" he causes the STD gonorrhea! YAY

Front 6

Neisseria meningitidis:

Back 6

In addition to causing meningitis, it can cause life-threatening sepsis (meningococcemi)

Front 7

Virulence factors of meningococcus (Neisseria meningitidis).

Back 7

1. Capsule: polysaccharide surrounds the bacterium (antiphagocytic) asuming no capsular antibodies are present. 9 serotypes: A, B, C, D, X, Y, Z, W135, and 29E). with ABC causing meningitis.

2. Endotoxin (LPS)- meningococci release "blebs" causing blood vessel destruction (hemorrhage) and sepsis. This can produce petechiae, and this same hemorrhaging process can damage adrenal glands.

3) IgA1 protease: Only found in pathogenic neisseria cleaves IgA in half.

4) Neisseria meningitidis, can extract iron from human transferrin via non-energy requiring mechanism.

(Usually exists in normal flora in nasopharynx in 5% of the population-->carriers. Carriers are lucky and are naturally immunized.

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High risk groups for Neisseria meningitis:

Back 8

1. Infants aged 6 mos. - 2 years
Maternal antibodies cross the placents and provide protection for a few months and then it takes time for infants to begin their own production, thus opening a window of susceptibility to meningococcal infection.


2. Army recruits- who are placed in tight-knit quarters. In close-knit groups carrier rates can exceed 40%. Due to mentally and physically exhausting training, the immune system's ability to defend itself is weakened.

Front 9

Meningococcal disease

Back 9

Usually resides asymptomatically in nasopharynx, rarely invading the bloodstream. The classic "clue" to an invasive meningococcal infxn. is petechial rash due to endotoxin from meningococcus, causing vascular necrosis, an inflammatory rxn, and hemorrhage into surrounding skin.

If you were to culture these skin petechia, you would find diplococci (kidney bean shape)

Front 10

Meningococcemia

Back 10

Intravascular multiplication of Neisseria meningitis results in:
1. spiking fevers
2. abrupt chills
3. arthralgia (joint pain)
4. muscle pains
5. petechial rash.

Once in the bloodstream, meningococci disseminate through body leading to meningitis and fulminant meningococcemia

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Fulminant meningococcemia

Back 11

Septic shock. bilateral hemorrhage into adrenal glands leading to adrenal insufficiency, hypotension, and tachycardia . DIC and coma can occurs Death can occur rapidly (6-8 hrs)

Front 12

Meningitis due to Neisseria

Back 12

Most common form of meningococcal disease usually striking infants.

Infants display nonspecific infxn. findings including :fever, vomiting, irritability, and lethargy. A buling anterior fontanelle is a key sign (with nucchal rigidity being a common finding in older infants).

Petechia skin findings allows presumptive dx. of meningitis w/o diagnostic spinal tap.

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Neisseria culture

Back 13

grows best on blood agar that has been heated until brown (chocolate agar).

Classic media is Thayer-Martin VCN media (which is basically chocolate agar with antibiotics which are intended to kill competing bacteria).

V-Vancomycin (kills gram + organisms by binding to the D-Ala-D-Ala)
C- colistin (polymixin) which kills non-neisseria gram negatives by disrupting outer and inner membranes

N- nystatin-eliminates fungi
C-

Front 14

Differentiation between neisseria species

Back 14

Neisseria meningitidis can produce acid from maltose metabolism.

Neisseria gonorrhea can't do this.

Front 15

Neisseria meningococcemia tx.

Back 15

(this is gram negative).

Use Peniccilin G or Ceftriaxone (a cephalosporin blocks PBP) at first indication of disseminated meningococcemia.

Close contacts are treated with rifampin.

Immunization with purified capsular polysaccharides from certain strains (A, C, Y, and W135) is currently available for epidemics and in high-risk groups. The group B polysaccharide does not induce immunity, so a vaccine is not available at present.

Front 16

Neisseria gonorrhoeae (gonococcus) and virulence

Back 16

Causes second most common STD (gonorrhea). Only second to chlamydial infections).

Virulence attributable to:

1.Pili: (neisseria gonorhoeae) has complex genes coding for pili which produce hypervariable amino acids in pili. Incurs protection from antibodies and vaccines. Pili can adhere to host and prevent phagocytosis by clinging bacteria so close to host cells.

2. Protein II (an outer membrane protein that, along with pili, aids in adherence to host cells)

Front 17

Gonococcal disease in men

Back 17

Unprotected sex with an infected person can lead to organismal penetration of urethra causing inflammation of the urethra.

Some main will remain asymptomatic, most will complain of painful urination and purulent urethral discharge.

Both asymptomatic and symptomatic men can pass it on.

Complications can include epididymitis, prostatitis, and urethral strictures. Fortunately a small dose ceftraixone regimin kills theese nasty little buggers.

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Gonococcal Disease in women

Back 18

Like men, women can develop gonococcal urethritis. But urethritis in women is more likely to be asymptomatic with minimal discharge.

(neisseria gonorrhea) also infects columnar epithelium of cervix, which becomes reddened and friable, with a purulent exudate.

If symptoms are present (much more rare than in men): you might expect low abdominal discomfort, pain with sex (dyspareunia) and a purulent vaginal discharge.

Again, asymptomatic does not mean they are not an infectious vector.

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Tx. for gonoccal disease in men

Back 19

Fortunately a small dose ceftraixone regimin kills theese nasty little buggers.

Front 20

Untreated gonoccal infection in women

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infection of the cervix can progress to PID (pelvic inflammatory disease) or "pus in dere."

PID is infected uterus (endometritis) fallopian tubes (salpingitis) and ovaries (oophoritis)

They can also have fever, low ab pain, menstrual bleeding (abnormal) and cervical motion tenderness (pain when cervix is moved by doc).

This bleeding (menstruation) can allow the bacteria to spread to upper genital tract.

IUD (intrauterine device) can increase risk of gonococcal infxn progressin to PID.

Chlamydia trachomotis is the other major cause of PID

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Complications of PID

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1. Sterility: (each gonorrhea infxn increases this risk). Scarring of the fallopian tubes--prevents sperm from reaching egg

2. Ectopic pregnancy: risk of a fetus developing at a site other than uterus is increased with previous fallopian tubes inflammation (salpingitis). Scarring in tubes leads to resistance in normal egg transit down tube.

3. Abscesses, may develop in the fallopian tubes, ovaries, or peritoneum

4. Peritonitis: bacteria may spread from ovaries and fallopian tubes to infect the peritoneal fluid.

5. Peri-hepatitis (Fitz-Hugh-Curtis Sndrome): This is an infxn by Neisseria gonorrhea of the capsule that surrounds the liver. A patient will complain of upper right quadrant pain and tenderness.

Front 22

gonococcal disease in both sexes

Back 22

Rarely can cause
1. Gonococcal bacteremia (invasion of blood stream, with clinical manifestations of fever, joint pains, and skin lesions (usually eruption on the cavities). Pericarditis, endocarditis, and meningitis are rare, but serious complications of disseminated infxn.

2. Septis arthritis: acute onset of fever occurs along with pain and swelling of 1 or 2 joints. W/o prompt antibotics, progressive joint destruction will occur. Synovial fluid exam reveals increased WBCs. Gram stain and culture of synovial fluid confirms gram-negative diplococci within the white blood cells.

Gonococcal arthritis is the most common kind of septic arthritis in young, sexually active individuals.

Front 23

Gonococcal disease in infants

Back 23

Can be transmitted from a pregnant woman to child during delivery resulting in opthalmia neonatorum (eye infxn.) Erythromycin eye drops are effective against neisseria gonorrhea and chlamydia and are given to newborns.

Gonococcal conjunctivitis can occur in adults.

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Diagnosis of Neisseria Gonorrhoeae

Back 24

Best made by gram stain and culture on Thayer-Martin VCN medium.

Pus removed from urethra by inserting a thin sterile swab. When this is gram stained and examined under the microscope, the tiny doughnut-shaped diplococci can be seen within the WBCs.

Front 25

Treatment of Neisseria gonorrhoeae

Back 25

The current therapy of choice is "Ceftriaxone"

In the past a combination of peniccilin G with probenicid was regmin of choice. however, there arose penicillinase-producing gonococcal strains and now an even tougher strain, with chromosomally-mediated antibiotic resistance to many antibiotics such as tetracycline, erythromycin, and trimethoprim/sulfamethoxazole. This resistance is mediated by a block in antibiotic pentration into the cell.

The current therapy of choice is "Ceftriaxone," a 3rd gen cephalosporins, spectinomycin or ciprofloxacin can be used as an alternative. The patient should also be treated at the same time with doxycycline or azithromycin for chlamydia trachomatis (because up to 50% of patients will be concurrently infected with this beta-lactam resistant bacteria.

Front 26

Branhamella catarrhalis (Neisseria Catarrhalis)

Back 26

Normal respiratory flora, but can cause otitis media, sinusitis, bronchitis, and pneumonia (all respiratory tract illnesses).

These bacteria produce beta-lactamaes and resistant to penicillin.