This document discusses pathogenic Enterobacteriaceae, including Shigella and Salmonella species. It provides details on the morphology, biochemical properties, antigenic structure, toxin production, and diseases caused by these bacteria. Key points include that Shigella dysenteriae produces a thermolabile exotoxin, Salmonella typhi contains endotoxins and exotoxins, and different serotypes of Shigella and Salmonella are distinguished based on their O, H, K, and Vi antigens.

1. Chair of Microbiology, Virology, and Immunology
PATHOGENIC
ENTEROBACTERIACEAE
Causative agents of Shigellosis and
Cholerae

2. The Enterobacteriaceae contain gram negative rods,
which, if motile, are peritrichously flagellated. Because
members of this family are morphologically and
metabolically similar, much effort has been expended to
develop techniques for their rapid identification. In general,
biochemical properties are used to define a genus, and
further subdivision frequently is based on sugar fermentation
and antigenic differences.

3. Classification of the Enterobacteriaceae
Genera
Escherichia Shigella
Edwardsiella Salmonella
Citrobacter Klebsiella
Enterobacter Hafnia
Serratia Proteus
Providencia Morganella
Yersinia Erwinia

5. O ANTIGENS. All gram-negative bacteria possess a
lipopolysaccharide (LPS) as a component of their outer
membrane. This toxic LPS (also called endotoxin) is
composed of three regions, lipid A, core, and are peating
sequence of carbohydrates called the O antigen. Based on
different sugars, alpha- or beta-glycosidic linkages, and the
presence or absence of substituted acetyl groups, Escherichia
coil can be shown to possess at least 173 different O antigens,
and 64 have been described in the genus Salmonella.

6. K ANTIGENS. K antigens exist as capsule or envelope
polysaccharides and cover the O antigens when present,
inhibiting agglutination by specific O antiserum. Most K
antigens can be removed by boiling the organisms in water.

7. H ANTIGENS. Only organisms that are motile possess H
antigens because these determinants are in the proteins that
makeup the flagella. However, to complicate matters,
members of the genus Salmonella alternate back and forth to
form different H antigens. The more specific antigens are
called phase 1 antigens and are designated by lower-case
letters (a, b, c, and so on), whereas the less-specific phase 2 H
antigens are given numbers.

8. Escherichia coli.
Morphology. E coli are straight rods measuring 0.4-0.7 in
breadth and 1-3 in length. They occur as individual
organisms or in pairs and are marked by polymorphism.
There are motile and non-motile types. The G+C content in
DNA is 50-51 per cent. The cell surface has pili on which
certain phages are adsorbed. The microcapsule is not always
clearly defined.

13. Fermentative properties. E. coli does not liquefy gelatin. It
produces indole and hydrogen sulphide, and reduces nitrates
to nitrites; ferments glucose, levulose, lactose, maltose,
mannitol, arabinose, galactose, xylose, rhamnose, and
occasionally saccharose, raffinose, dulcitol, salycin, and
glycerin, with acid and gas formation. It also coagulates
milk. There are varieties of the bacteria which ferment
saccharose, do not produce indole, have no flagella, and do
not ferment lactose.

14. Toxin production.
- a gluco-lipo-protein complex with which their toxic,
antigenic, and immunogenic properties are associated;
- haemolytic properties (O124 and others)
- endotoxins and thermolabile neurotropic exotoxins;
- haemotoxins and pyrogenic substances, proteinases,
deoxyribonucleases, urease, phosphatase, hyaluronidase,
amino acid decarboxylases

16. Escherichia coif Virulence Factors
Diarrhea-producing
E. coli
Virulence Factors
Enteroroxigenic E. coli Heat-labile toxin (LT)
Heat-stable toxin (ST)
Colonization factors (fimbriae)
Enterohernorrhagic E. coli Shiga like toxin (SLT-I)
Shiga like toxin II (SLF-II)
Colonisation factors (fimbriae)
Enteroinvasive E. coli Shiga like toxin (SLT-I)
Shiga like toxin II (SLF-II)
Ability to invade epithelial cells
Enteropathogenic E. coli Adhesin factor for epithelial cells
Urinary trace infections P- fimbriae
Meningitis K-1 capsule

17. Pathogenesis and diseases in man. Definite E. coli
serogroups are capable of causing various acute intestinal
diseases in humans: (1) the causative agents of
colienteritis in children are O-groups-25, -26, -44, -55, -
86, -91, -111, -114, -119, -125, -126, -127, -128, -141, -146,
and others (they cause diseases in infants of the first months
of life and in older infants); (2) the causative agents of
dysentery-like diseases are E. coli of the O-groups-23, -32,
-115, -124, -136, -143, -144, -151, and others; (3) the
causative agents of cholera-like diarrhoea are the O-
groups-6, -15, -78, -148, and others, they produce
thermolabile and thermoresistant enterotoxins.

22. Laboratory diagnosis. The patients' faeces, throat and nasal
discharges, material obtained at autopsy (blood, bile, liver,
spleen, lungs, contents of the small and large intestine, pus),
water, foodstuffs, and samples of washings from objects and
hands of staff of maternity hospitals, hospitals, and dairy
kitchens are all used for laboratory examination during
colienteritis. If possible, faecal material should be seeded
immediately after it has been collected. The throat and nasal
discharges are collected with a sterile swab. Specimens of
organs obtained at autopsy are placed in separate sterile jars.

23. Enteric Fever,
Paratyphoid Salmonellae

24. Classification of Salmonella
Genus Salmonella
Species: Salmonella enterica
Salmonella bongory
Subspecies Salmonella enterica
a. S. choleraesuis
b. S. salamae
c. S. arizonae
d. S. diarizonae
e. S. houtenae
f. S. indica

25. Morphology. The morphology of the typhoid salmonella
corresponds with the general characteristics of the
Enterobacteriaceae family. Most of the strains are motile and
possess flagella, from 8 to 20 in number. It is possible that the
flagella form various numbers of bunches.

31. Toxin production. S. typhi contains gluco-lipoprotein
complexes. The endotoxin is obtained by extracting the
bacterial emulsion with trichloracetic acid. This endotoxin is
thermostable, surviving a temperature of 120° C for 30
minutes, and is characterized by a highly specific precipitin
reaction and pronounced toxic and antigenic properties.
Investigations have shown the presence of exotoxic
substances in S. typhi which are inactivated by light, air, and
heat (80° C), as well as enterotropic toxin phosphatase, and
pyrogenic substances.

32. Antigenic structure. S. typhi possesses a flagellar H-antigen
and thermostable somatic 0- and Vi-antigens. All three
antigens give rise to the production of specific antibodies in
the body, i. e. H-, O-, and Vi-agglutinins. H-agglutinins bring
about a large-flocculent agglutination, while 0- and Vi-
agglutinins produce fine-granular agglutination.

34. Classification. At present, about 2000 species and types of this
genus are known.
F. Kauffmann and P. White classified the typhoid-paratyphoid
salmonellae into a number of groups according to antigenic
structure and determined 65 somatic O-antigens. For instance, S.
typhi (group D) contains three different O-antigens — 9, 12, and
Vi. S. paratyphi A alone constitutes group A, and S. schottmuelleri
belongs to group B. It has been proved by F. Andrewes that the
flagellar H-antigen is not homogeneous but is composed of two
phases: phase 1 is specific and agglutinable by specific serum,
phase 2 is non-specific and agglutinable not only by specific, but
also by group sera. Salmonellae, which possess two-phase H-
antigens, are known as diphasic, while those which possess only
the specific H-antigen are monophasic.

35. Pathogenesis and diseases in man. The causative agent is
primarily located in the intestinal tract. Infection takes place
through the mouth (digestive stage).
Cyclic recurrences and development of certain
pathophysiological changes characterize the pathogenesis of
typhoid fever and paratyphoids.
There is a certain time interval after the salmonellae
penetrate into the intestine, during which inflammatory
processes develop in the isolated follicles and Peyer's
patches of the lower region of the small intestine (invasive
stage).

36. As a result of deterioration of the defence mechanism of the
lymphatic apparatus in the small intestine the organisms
enter the blood (bacteriemia stage). Here they are partially
destroyed by the bactericidal substances contained in the
blood, with endotoxin formation. During bacteraemia
typhoid salmonellae invade the patient's body, penetrating
into the lymph nodes, spleen, bone marrow, liver, and other
organs (parenchymal diffusion stage). This period
coincides with the early symptoms of the disease and lasts
for a week.

37. On the third week of the disease a large number of typhoid
bacteria enter the intestine from the bile ducts and
Lieberkuhn's glands. Some of these bacteria are excreted in
the faeces, while others reenter the Peyer's patches and
solitary follicles, which had been previously sensitized by the
salmonellae in the initial stage. This results in the
development of hyperergia and ulcerative processes. Lesions
are most pronounced in Peyer's patches and solitary follicles
and may be followed by perforation of the intestine and
peritonitis (excretory and allergic stage).
The typhoid-paratyphoid salmonellae together with products
of their metabolism induce antibody production and promote
phagocytosis. These processes reach their peak on the fifth-
sixth week of the disease and eventually lead to recovery
from the disease.

38. Clinical recovery (recovery stage) does not coincide with the
elimination of the pathogenic bacteria from the body. The
majority of convalescents become carriers during the first
weeks following recovery, and 3-5 per cent of the cases
continue to excrete the organisms for many months and years
after the attack and, sometimes, for life. Inflammatory
processes in the gall bladder (cholecystitis) and liver are the
main causes of a carrier state since these organs serve as
favourable media for the bacteria, where the latter multiply
and live for long periods. Besides this, typhoid-paratyphoid
salmonellae may affect the kidneys and urinary bladder,
giving rise to pyelitis and cystitis. In such lesions the
organisms are excreted in the urine.

39. Immunity. Immunity acquired after typhoid fever and
paratyphoids is relatively stable but relapses and
reinfections sometimes occur. Antibiotics, used as
therapeutic agents, inhibit the immunogenic activity of
the pathogens, which change rapidly and lose their O-
and Vi-antigens.

40. Laboratory diagnosis. The present laboratory diagnosis of
typhoid fever and paratyphoids is based on the pathogenesis
of these diseases.
1. Isolation of haemoculture. Bacteraemia appears during
the first days of the infection.

41. 2. Serological method. Sufficient number of agglutinins
accumulate in the blood on the second week of the disease,
and they are detected by the Widal reaction. Diagnostic
typhoid and paratyphoid A and B suspensions are employed
in this reaction. The fact that individuals treated with
antibiotics may yield a low titre reaction must be taken into
consideration. The reaction is valued positive in patient's
serum in dilution 1 : 200 and higher.

42. 3. A pure culture is isolated from faeces and urine during the
first, second, and third weeks of the disease. The test material
is inoculated into bile broth, Muller's medium, Ploskirev's
medium, or bismuth sulphite agar.

43. Treatment. Patients with typhoid fever and paratyphoids are
prescribed chloramphenicol, oxytetracycline, and nitrofuran
preparations.
These drugs markedly decrease the severity of the disease
and diminish its duration.
Great importance is assigned to general non-specific
treatment (dietetic and symptomatic).
The eradication of the organisms from salmonellae carriers is
a very difficult problem.

44. Prophylaxis. General measures amount to rendering
harmless the sources of infection. This is achieved by timely
diagnosis, hospitalization of patients, disinfection of the
sources, and identification and treatment of carriers. Of great
importance in prevention of typhoid fever and paratyphoids
are such measures as disinfection of water, safeguarding
water supplies from pollution, systematic and thorough
cleaning of inhabited areas, fly control, and protection of
foodstuff's and water from flies. Washing of hands before
meals and after using the toilet is necessary. Regular
examination of personnel in food-processing factories for
identification of carriers is also extremely important.

45. In the presence of epidemiological indications
specific prophylaxis of typhoid infections is
accomplished by vaccination. Several varieties of
vaccines are prepared: typhoid vaccine
(monovaccine), typhoid and paratyphoid B
vaccine (divaccine).

46. Causative agents of Shigellosis
and Cholerae

47. The causative agent of dysentery was described in 1888
by A. Chantemesse and in 1891 by A. Grigoryev and F.
Widal. In 1898 this organism was studied in detail by
K. Shiga in Japan and in 1900-1901 by V. Kruse in
Germany (Shiga bacillus).
Causative agents of Shigellosis

48. Morphology. Morphologically dysentery bacilli
correspond to the organisms of the family
Enterobacteriaceae. Dysentery bacilli have no flagella and
this is one of the differential characters between these
organisms and bacteria of the coli-typhoid-paratyphoid
group. Some strains of Flexner bacilli are found to possess
cilia.

50. Subgroup Fermentation of carbohydrates
Indole
production
Catalase
lactose
glucose
mannite
succrose
succrose
S. dysenteriae – A – + – – – – –
S. fiexneri – B – + + + – – +
S. boydii – C – + + + – + –
S. sonnei – D +
slowly
+ + – +
slowly
– +
Shigellae Biochemical Properties

52. Toxin production. S. dysenteriae produce
thermolabile exotoxin which displays marked tropism
to the nervous system and intestinal mucous
membrane. This toxin may be found in old meat broth
cultures, lysates of a 24-hour-old agar culture, and in
desiccated bacterial cells.

53. The dysentery exotoxin causes the production of a
corresponding antitoxin. The remaining types of
dysentery bacilli produce no soluble toxins. They
contain endotoxins, which are of a gluco-lipo-protein
nature, and occur in the smooth but not in the rough
variants.
Thermolabile substances exerting a neurotropic effect
were revealed in some S. sonnei strains. They were
extracted from old cultures by treating the latter with
trichloracetic acid.

54. Subgroup Species and
serotype
Subse-
rotypes
Antigenic formula
Type
antigen
Group
antigens
A. Does not
ferment mannite
S.dysenteria
1-12
B. Ferments
mannite as a rule
S. flexneri
1, 2, 3, 4, 5,
6, X variant
Y variant
1a, 1b,
2a, 2b,
3a, 3b,
4a, 4b
I, II, III,
IV, V, VI
2, 3, 4,
6, 7, 8
C. Ferments
mannite as a rule
S. boydii,
1-18
D. Ferments
mannite, slowly
lactose and
saccharose
S. sonnei
Antigens

55. Epidemiology and Pathogenesis of Shigellosis. Humans
seem to be the only natural hosts for the shigellae, becoming
infected after the ingestion of contaminated food or water.
Unlike Salmonella, the shigellae remain localized in the
intestinal epithelial cells, and the debilitating effects of
shigellosis are mostly attributed to the loss of fluids,
electrolytes, and nutrients and to the ulceration that occurs in
the colon wall.
It has been known for many years that Shigella dysenteriae
type 1 secreted one or more exotoxins (called Shiga toxins),
which would cause death when injected into experimental
animals and fluid accumulation when placed in ligated
segments of rabbit ileum.

58. Laboratory diagnosis. Reliable results of laboratory
examination depend, to a large extent, on correct
sampling of stool specimens and its immediate
inoculation onto a selective differential medium. The
procedure should be carried out at the patient's
bedside, and the plate sent to the laboratory.

59. For the serological diagnosis of dysentery the indirect
haemagglutination (IHA) test with erythrocyte
diagnosticums with the titre of 1:160 and higher is
performed. The test. is repeated after at least seven days.
Diagnostically important is a four-fold rise in the anti-
body litre, which can be elicited from the 10th-12th day
of the disease. To distinguish between patients with
subclinical forms of the disease and Shigella carriers,
identify immunoglobulins of the G class.

60. Treatment and Control of Shigellosis
Intravenous replacement of fluids and electrolytes plus
antibiotic therapy are used for severe cases of
shigellosis. Ampicillin frequently is not effective, and
alternative therapies include sulfamethoxazole/
trimethoprim and, with increasing sulfamethoxazole/
trimethoprim resistance, the quinolone antibiotics such
as nalidixic acid and ciprofloxacin.
In the Far East, India, and Brazil where shigellosis is
more common than in the United States, multiple
antibiotic resistance because of the acquisition of
plasmids has become common. Shigellosis also is
common in Latin America.

61. The injection of killed vaccines is worthless, because humoral
IgG does not seem to be involved in immunity to the localized
intestinal infection.
Live vaccines that cannot grow in the absence of streptomycin
(ie, streptomycin-dependent vaccines) have been developed and
used in clinical trials, but success has been equivocal.

62. Summary
SHIGELLA
1. Genus characteristics
a. Slender, gram-negative rod; non lactose-fermenting
(except for S. sonnei)
b. In contrast to E. coli: no H2S production, no lysine
decarboxylation, no acetate utilization
c. Invasive (key to pathogenesis)
d. In contrast to Salmonella: non-motile; no gas from
glucose fermentation; no H2S production
e

63. e. Toxin production limited to a few strains
f. All have O antigens-four groups (A-D)
g. Differentiating species
i. S. dysenteriae - no mannitol fermentation
ii. S. boydii - C antigen group
iii. S. flexneri - B antigen group
iv. S. sonnei-orniltine decarbexylase production

64. h. Specimens
i. Rectal swab from colonic ulcer is best for culture.
ii. Fecal specimen - must be immediately innoculated onto
transport media or culture media.
Sensitive to acids present in feces.

65. 2. Epidemiology
a. Species
i. S. sonnei most frequent isolate in U.S.
ii. S. dysenteriae and S. boydii most frequently isolated in
developing countries - cause more severe disease course.
iii. S. flexneri more commonly isolated from homosexual
men
b. Humans and higher primates are only natural reservoir.
c. High communicability (< 200 bacilli needed to produce
disease)
d. May be spread by fomites;”food, fingers, feces, and
files”.

66. 3. Clinical manifestations
a. Desease - bacillary dysentery (shigellosis), characterized
by painful, frequent, low-volume stools; feces contain blood
and mucous. Bacteremia is rare since organisms usually do
not enter bloodstream. Polymorphonuclear leukocyles
present in stool.
b. Carriers
i. One to four weeks after the disease; carrier state may be
set up if organism is not cleared.
ii. Long-term; recurrent bouts of disease

67. 4. Therapy and prevention
a. Hydration and electrolyte replacement
b. Ampicillin - decreases duration of symptoms and
carrier state; tetracycline; trimethoprim-
sulfamelhoxazole
c. Prevention through personal hygiene, proper garbage
disposal and water purification.

68. Vibrio Cholerae

69. The causative agents of cholera are the classical
Vibrio cholera biovars discovered by R. Koch in
1883 and the El Tor vibrio biovar isolated from the
cadaver of a pilgrim on the Sinai peninsula by
Gotschlich in 1906. Vibrio cholerae biovar Proteus
(N. Gamaleya, 1888) and Vibrio cholerae biovar
albensis were discovered" later. V. cholerae was
described by F. Pacini in 1854.

70. Classification. Vibrio cholerae belongs to family
Vibrionaceae, genus Vibrio consisting of 5 species. The
species Vibrio cholerae is subdivided into four biological
variants: biovar cholerae, biovar El Tor, biovar
Proteus, and biovar albensis.
Biovar cholerae and biovar El Tor of Vibrio cholerae are
the causative agents of human cholera. Biovar Proteus of
Vibrio cholerae causes diarrhoea in birds and
gastroenteritis in humans; biovar albensis of Vibrio
cholerae was revealed in fresh water and in human faeces
and bile.

71. Morphology. Cholera vibrios are shaped like a
comma or a curved rod measuring 1-5 mcm in length
and 0.3 mcm in breadth
They are very actively motile, monotrichous,
nonsporeforming, noncapsulated, and Gram-negative.

72. Vibrio cholerae: 1-pure culture; 2- flagellate
vibrios

74. Cultivation. Cholera vibrios are facultative (anaerobes).
The optimum growth temperature is 37° C, and growth is
arrested below 14 °C and above 42° C. The organisms grow
readily on alkaline media at pH 6.0-9.0, and on solid media
the colonies are transparent with a light-blue hue, forming
domes with smooth edges.

75. Vibrio
Fermentation
within 24 hrs
Sheep
erythrocyte
hemolysis
Lysis
by
specific
O-1
subgroup
phages
Agglutination
by
O-1
cholera
serum
Sensitivity
to
polymixin
B
sacharose
mannose
arabinose
Vibrio cholerae
biovar cholerae
A A – – + + +
Vibrio cholerae
biovar El Tor
A A – + + + –
Vibrio cholerae
biovar Proteus
A A – + – – –
Vibrio cholerae
biovar albensis
А – – – – – –
Fermentative properties

76. Toxin production. The cholera vibrio produces an
exotoxin (cholerogen) which is marked by an
enterotoxic effect and plays an important role in the
pathogenesis of cholera; the endotoxin also exerts a
powerful toxic effect. The cholera vibrios produce
fibrinolysin, hyaluronidase, collagenase, mucinase,
lecithinase, neuraminidase, and proteinases.

77. Remember that non-O1 and non-O139 strains of
V.cholerae also cause a wide spectrum of infections,
ranging from mild diarrhea to one indistinguishable
from classic cholera. Some of these serotypes are
known to produce a choleratoxin that is identical to
that of the classic biotypes, whereas other products a
heat-stable enterotoxin analogous to the ST of E. coli.

80. Antigenic structure. The cholera vibrios have
thermostable O-antigens (somatic) and thermolabile H-
antigens (flagellar). The O-antigen possesses species
and type specificity, the H-antigen is common for the
genus Vibrio. The cholerae vibrios, El Tor biovars and
biovars cholera belong to the O-1 subgroup.

81. Pathogenesis and diseases in man. Cholera is
undoubtedly the most dramatic of the water-borne
diseases. As far as is known, cholera was confined to
India for the almost 2000 years between its first
description by Hindu physicians in 400 b c and its spread
to Arabia, Persia, Turkey, and Southern Russia in the
early1800s. There were six major pandemics of cholera
during the 1800s covering the entire world, killing
millions wherever it struck.

83. Three phases can be distinguished in the development of
the disease.
1. Cholera enteritis (choleric diarrhoea) which lasts 1 or 2
days.
2. Cholera gastroenteritis. Profuse diarrhoea and continuous
vomiting lead to dehydration of the patient's body and this
results in lowering of body temperature, decrease in the
amount of urine excreted, drastic decrease in the number of
mineral and protein substance, and the appearance of
convulsions. The presence of cholera vibrios is revealed guite
frequently in
3. Cholera algid which is characterized by severe symptoms.
The skin becomes wrinkled due to the loss of water, cyanosis
appears, and the voice becomes husky and is sometimes lost
completely. The body temperature falls to 35.5-34 °C. As a
result of blood concentration cardiac activity is drastically
weakened and urination is suppressed.

85. Laboratory diagnosis. A strict regimen is established
in the laboratory. Examinations are carried out in
accordance with the general rules observed for
particularly hazardous diseases.
Test specimens are collected from stools, vomit,
organs obtained at autopsy, water, objects
contaminated by patient's stools, and, in some cases,
from foodstuffs. Certain rules are observed when the
material is collected and transported to the laboratory,
and examination is made in the following stages.

86. 1. Stool smears stained by a water solution of fuchsin are
examined microscopically. In the smears, the cholera
vibrios occur in groups similar to shoals of fish (Fig. 3).
2. A stool sample is inoculated into 1 per cent peptone
water and alkaline agar. After 6 hours incubation at 37°C
the cholera vibrios form a thin pellicle in the peptone
water, which adheres to the glass. The pellicle smears are
Gram stained, and the culture is examined for motility. A
slide agglutination reaction is performed with specific
agglutinating O-serum diluted in a ratio of 1 in 100.

87. Vibrio cholerae (stool smear)

88. The organisms are then transferred from the peptone
water onto alkaline agar for isolation of the pure culture.
If the first generation of the vibrios in peptone water is
not visible, a drop taken from the surface layer is re-
inoculated into another tube of peptone water. In some
cases with such re-inoculations, an increase in the
number of vibrios is achieved.
The vibrio culture grown on solid media is examined for
motility and agglutinable properties. Then it is
subcultured on an agar slant to obtain the pure culture.

89. 3. The organism is identified finally by its
agglutination reaction with specific O-serum,
determination of its fermentative properties
(fermentation of mannose, saccharose, and arabinose),
and its susceptibility to phagolysis

90. Treatment. The mortality rate of cholera can be reduced
to less than1% by the adequate replacement of fluids and
electrolytes. Antibiotics of the tetracycline group
(tetracycline, sigmamycin), amphenicol, and streptomycin
are prescribed at first intravenously and then by mouth.
Pathogenetic therapy is very important: control of
dehydration, hypoproteinaemia, metabolic disorders, and
the consequences of toxicosis, acidosis in particular, by
infusion of saline (sodium and potassium) solutions,
infusion of plasma or dry serum, glucose, the use of warm
bath, administration of drugs which improve the tone of
the heart and vessels.

91. Prophylaxis. The following measures are applied in a cholera
focus:
(1) detection of the first cases with cholera, careful
registration of all sick individuals, immediate information of
health protection organs;
2) isolation and hospitalization, according to special rules,
of all sick individuals and carriers, observation and
laboratory testing of all contacts;
(3) concurrent and final disinfection in departments for
cholera patients and in the focus;

92. (4) protection of sources of water supply, stricter sanitary
control over catering establishments, control of flies; in
view of the possibility of El Tor vibrio reproducing in
water reservoirs under favourable conditions
(temperature, the presence of nutrient substrates)
systematic bacteriological control over water reservoirs
has become necessary, especially in places of mass rest
and recreation of the population in the summer;

93. (5) strict observance of individual hygiene; boiling or
proper chlorination of water, decontamination of
dishes, hand washing;
(6) specific prophylaxis: immunization with the
cholera monovaccine containing 8 thousand million
microbial bodies per 1 ml or with the cholera anatoxin.
Chemoprophylaxis with oral tetracycline is conducted
for persons who were in contact with the sick
individual or for patients with suspected cholera.

94. SUMMURY
I. GENUS VIBRIO
A. GENERAL CHARACTERISTICS
1. From family Vibnonaceae
2 Naturally occur in water-marine and fresh waters; some
occur in cold-blooded animals.
3. Oxidase-positive-differentiates Vibrios from
Enterobacteriaceae.
4. Characteristic comma shape

95. B VIBRIO CHOLERAE
1 Species characteristics
a. Comma-shaped when first isolated
b. Aerobic
c. Unipolar flagellum-motile
d. Primary isolation-simple media, MacConke/s agar,
tellurite taurocholate gelatin agar (TTGA),
thiosulfate citrate bile salts agar (TCBS)
e. Sensitive to 2,4-diamme-6,7 d isopropyi pteridine
(0/129), useful in distinguishing from other
gram-negative, oxidase-posilive bacilli (i.e., Aeromonas)
f. Prefer alkaline environment.

96. 2. Serogroups-based on O antigen type
a. V.cholerae O-1
i. Agglutinate antisera against O-1 antigen.
ii. Classic epidemic and pandemic Asiatic cholera; most virulent
serogroup
iii. Produce disease via enterotoxin (heat-labile toxin produciog-
secretory diarrhea via cyclic AMP).
iv. Subdivided biochemically into Cholerae and El Tor biotypes
b. Atypical V. cholerae O-1
i. Agglutinate antisera against O-1 antigen.
ii. Do not cause human disease.
in. Do not elaborate classic cholera enlerotoxin, '
c. Non O-1 V cholerae
i. Fail to agglutinate O-1 antisera.
ii. Biochemically and genetically indistinguishable from the O-1
group
iii. Cholera-like diarrhea; rareirr extrainistinal infection

97. 3. Determinants of pathogenicity
a. Adherence to small intestine epithelium - non-invasive
infection
b. Pathogenicily related to host response to (he enterotoxin
(choleragen); humans only host that has pathogenic
response
c. Two major enterotoxin subunits
i. A subunit-A1 peptide promotes activation of adenylate
cyclose
ii.  subunit - binds toxin to small intestinal ganglioside
receptor
d. Principal effect is increased intracettular cyclic AMP
resulting in electrolyte/fluid secretion into small intestine
lumen.

98. 4. Clinical manifestations: Cholera
a Incubation of 1-4 days
b Severe, watery ("rice water") diarrhea with loss of
sodium, chloride, potassium, and bicarbonate
c Associated with nausea, vomiting and abdominal cramps
d Metabolic acidosis
e. Hypovolemic shock
f. Mortality rate without treatment 25-50%

99. 5. Therapy and prevention
a. Rapid rehydration and electrolyte replacement
i. Intravenous in severe cases
ii. Oral therapy in milder cases
b. Tetracycine (oral)
i. Reduces number of organisms.
ii. Decreases degree of stool output
iii. Helps eliminate chronic carrier slate
iv. Resistant forms recognized in Africa-plasmid
mediated
v. Not indicated for prophylaxis
c. Present vaccine does not afford adequate protection
d. Gastric acidity affords some protection.
e. Infection does provide non-lasting immunity to
reinfection

100. C. VIBRIO PARAHEMOLYTICUS
1. Species characteristics
a. Resembles V. cholerae structurally.
b. Halophilic, requiring at least 2 % NaCl for growth
(in contrast to V.cholerae which does not grow in saline)
c O and K antigens useful for serologic typing
d. Isolates causing diarrhea produce hemolysm
(Kanawaga positive)

101. 2. Clinical manifestations
a. Most cases of diarrhea attributed to mgestion of raw
or improperly handled seafood
b. Incubation period 12-24 hours
c. Explosive watery diairhea, headache, abdominal
cramps, fever, and vomiting. Note: Diarrhea may be bloody.
d. Cloudy swelling, fatty infiltration of liver
e. Septicemia (particularly with underlying liver
disease)
Localized wound infections from contamination of sea
water

102. 3. Therapy and prevention
a. Mild disease usually self-limiting; no therapy
required. Usually subsides within 2-4 days
b. For severe case, fluid and electrolyte replacements,
antibiotics
c. Organisms usually sensitive to chloramphemcol,
tetracychne, and cephalosporins
d. Adequate refrigeration of raw and cooked seafood
aid in prevention

103. D OTHER VIBRIO INFECTIONS
1. V. alginotyticus
a. Affects wounds, eyes and ears in person with injuries or seawater
contact.
b. Septicemia - unusual
c. No known intestinal disease
2. V. vulnificus
a. Wound infection with intense pustules or bullae
b. Septicemja
c. Occasionally produce enteritis.
3. V.fluvialis,V.hollisae
a. Severe diarrhea in children in Bangladesh
b. Abdominal pain, lever, bloody mucus in stool
4 V.mimicus - diarrneal illness from uncooked seafood, especially
oysters

104. OTHER GENERA FROM FAMILY VIBRIONACEAE
A. GENUS AEROMONAS
1. Genus characteristics
a. Free-living, gram-negative rods located in fresh water and rarely
marine life
b. A. hydrophila is most important species
c. Oxidase-posilive (differentiates from gram-negative enteric's).
Produce large zone of hemolysis on blood agar.
d Single polar flagellum - motile
e. Resistance to compound O129 and lack of growth in NaCI solution
differentiates from Vibrios
2 Clinical manifestations
a Causes diarrhea, septicemia, osteomyelills, and wound infection,
usually in immunocompromised patients
b. Isolated from patients with and without diarrheal disease
3. Therapy - usually sensitive to aminoglycosides, tetracycline, and
cephalosporins

105. B GENUS PlESIOMONAS
1 Genus characteristics
a. A gram-negative rod with polar flagella found in tropics
and sub-tropics
b. Oxidase-positive - important to differentiate from
Shigella as they share common antigens
c. Has arginine, ornithine, and lysine decarboxylase -
distinguishes from Aeromonas.
2. Clinical manifestations
a. P. shigelloides primarily causes gastroenteritis
b. Has been isolated from blood and spinal fluid

106. CAMPYLOBACTER
A CENUS CHARACTERISTICS
1 Isolation of comma-shaped motile gram-negative organisms
from rectal or stool specimens cultured selective media containing
various antibiotics that inhibit other fecal flora
a. Campy-BAP-vanco, polymixin, trimethoprim and cephalothin
b. Skirrow's medium-vancomycin, polymixin B and trimethoprim
c. Butzler's medium
2. Microaerophilic - grows best in 5 % O2 (compared to 20%
atmospherically) present.
3. Do not oxidize or ferment carbohydrates.
4. Oxidase and catalase positive
5. Reservoir: domestic animals such as dogs, cows, and chicken
6. Fecal-oral transmission

107. B C. JEJUNI
Species characteristics
a. Grows at 39 C and 42C with candle jar, 42 will
inhibit growth of other bacteria that are present (including
C. intestinalis)
b. Nalidixic acid sensitive (in contrast to C.intestimalis)
2. Clinical manifestations: Enterocolitis
a. Invasive enteritis with bloody diarrhea, crampy
abdominal pains, malaise and fever – usually limited to 1-
week period; more common in children
b. Inflammatory proctitis in homosexuals
c. Reactive arthritis may follow in individuals HLA-B27(+).
3. Thefapy - erythromycin

108. C. C. INTESTINALIS (C. FETUS SUBSP. FETUS)
1. Species characteristics
a. Grows best at 25 C and 37 C and poorly at 42 C (in
contrast to C.jejuni)
b. Nalidixic asid resistant
2. Clinical manifestation
a. Bacteremia
b. Opportunistic pathogen in debilitated patients
c. May localize to peritoneum, pleura, lung, pericardium,
j joints, or meninges.
d. May cause localized diarrheal illness.
3. Therapy - aminoglycoside

109. C. HELICOBACTER PYLORI (previously C. pylori)
1. Species characteristics
a. Spiral-shaped, motile rod
b. Produces urease
c. Present in gastric mucosa of fewer than 20% of people
less than 30 years old but increases to greater than 50% of
people over 60 years old, even in asymptomatic patients
d. Optimal growth at pH 6 0-7.0; organism is sheltered
from lumenal acidity by embedding into gastric mucosa.

110. 2 Clinical manifestations
a. Associated with antral gastritis and peptic ulcer disease
b. No direct evidence that organism causes disease but
strong association exists
c. Eradication of H. pylori will help heal peptic ulcer and
improvement of gastritis.
3. Diagnosis
a. Best made histologically via biopsy with ulceration and
gastritis seen with Giemsa stain;
characteristic intra-epithelial curved organisms
b Urease test is used for presumptive presence of H. pylori
4. Therapy - long term (1 month) therapy with bismuth
(Pepto Bismol), ampicillin, and metronidazole