Download MBBS (Bachelor of Medicine, Bachelor of Surgery) General Medicine 2022 PPT 3 Gn Infections Part I Lecture Notes
Infectious diseases
4/5th Semester Classes on Infectious Diseases, 8-9AM, Tuesdays (LT-1)
Topics
1
Approach to Infectious Diseases and their prevention
2
Antibiotic stewardship practices
3
Community-Acquired Infections
4
Health Care?Associated Infections
5
Gram-Positive Bacteria (part-1)
6
Gram-Positive Bacteria (part-2)
7
Gram-Negative Bacteria (part-1)
8
Gram-Negative Bacteria (part-2)
9
Spirochetal Diseases
10
Diseases Caused by Atypical/Miscellaneous Bacterial Infections
11
Revision-cum-exam on bacteria (Must to know type)
12
Infections Due to DNA Viruses
1
13
Infections Due to RNA Viruses (part 1)
14
Infections Due to RNA Viruses (part 2)
15
HIV/AIDS ? part 1
16
HIV/AIDS ? part 2
17
Fungal Infections
18
Parasitic Infections (part 1)
19
Parasitic Infections (part 2)
20
Revision-cum-exam on Virus, Fungal, and Parasite (Must to know type)
NEISSERIA
ENTEROBACTERIACEAE
PSEUDOMONADS
BRUCELLA
(E. coli, Klebsiella,
Proteus, Enterobacter)
HAEMOPHILUS
SALMONELLA
ACINETOBACTER
FRANCISELLA
LEGIONELLA
SHIGELLA
HELICOBACTER
YERSINIA
BORDETELLA
VIBRIO
CAMPYLOBACTER
BARTONELLA
NEISSERIA (N. meningitis & N. gonorrhoeae; IP-2-7days)
N. meningitis; diplococcus that colonizes in the nasopharynx of healthy
adolescents and adults, use glucose and maltose to produce acid
N. gonorrhoeae; grow on selective media and to use glucose but not maltose,
sucrose, or lactose
Meningococci invasive disease are usually encapsulated with polysaccharide,
and the antigenic nature of the capsule determines an organism's serogroup
Under capsule, an outer phospholipid membrane containing lipopolysaccharide
(LPS, endotoxin) and multiple outer-membrane proteins (serotype)
Gonococcus contains, on average, three genome copies per coccal unit; this
polyploidy permits a high level of antigenic variation and the survival of the
organism in its host and resistant to antibiotics
Outer-Membrane Proteins (PILLI, OPA, PORIN, etc) and lipooligosaccharide
(LOS): gonococcal structures that interact with epithelial cells, host factors seem
to be important in mediating entry of gonococci into nonphagocytic cells (e.g.
complement deficiency)
There are several patterns of disease: epidemic, outbreak, hyperendemic, and
sporadic or endemic
Clusters of cases occur where there is an opportunity for increased transmission--
i.e., in (semi-)closed communities
Smoking, crowding, and respiratory viral infection increase the risk of
carriage/disease
Endothelial injury is central to many clinical features of meningococcemia,
including increased vascular permeability, pathologic changes in vascular tone,
loss of thromboresistance, intravascular coagulation, and myocardial dysfunction
Most common clinical syndromes are meningitis and meningococcal septicemia
MENINGITIS: While 30?50% of patients present with a meningitis syndrome alone
OR up to 40% with some features of septicemia
SEPTICEMIA: alone accounts for up to 20% of cases
CHRONIC MENINGOCOCCEMIA, presents as repeated episodes of petechial rash
associated with fever, joint pain/arthritis, and splenomegaly that may progress to
acute meningococcal septicemia if untreated
POSTMENINGOCOCCAL REACTIVE DISEASE, an immune complex disease develops
~4?10 days after the onset of meningococcal disease
Usually initially blanching in nature and indistinguishable from viral rashes, HOWEVER,
petechial or frankly purpuric over the hours after onset, THEN purpura fulminans
(fewer than <10% of children of all rashes) ? (occurs in two-thirds of Meningococcal cases)
Clinical grounds and lab confirmation (blood cultures are positive in up to 75%
of cases, (PCR) analysis of whole-blood samples, lumbar puncture
Third-generation cephalosporin, treated for 7 days
10% DEATH, most common complication 10% of cases) is scarring after necrosis
of purpuric skin lesions
Factors associated with a poorer prognosis are shock; young age (infancy),
old age, and adolescence; coma; purpura fulminans; disseminated
intravascular coagulation; thrombocytopenia; leukopenia; absence of
meningitis; metabolic acidosis; low plasma concentrations of antithrombin and
proteins S and C; high blood levels of PAI-1; and a low erythrocyte
sedimentation rate or C-reactive protein level
PREVENTION;
1. Immunization- Polysaccharide Vaccines/Conjugate Vaccines/Vaccines Based
on Subcapsular Antigens
A monovalent serogroup A vaccine, manufactured in India, was licensed in 2010
and rol ed out to countries in the sub-Saharan African meningitis belt
Chemoprophylaxis- Rifampin/Ceftriaxone as a single IM or
IV/Ciprofloxacin/ofloxacin
GONORRHEA
Gonorrhea is a sexually transmitted infection (STI) of epithelium and commonly
manifests as cervicitis, urethritis, proctitis, and conjunctivitis
Gonococcal Infections in Men
Gonococcal Infections in Women
Acute urethritis
Cervicitis
(more acute and intense than those
of chlamydial cervicitis)
Epididymitis/prostitis
Urethritis
Balanitis or further deep complications
Vaginitis
including abscesses
(occur in anestrogenic
Women)
Anorectal Gonorrhea
Pharyngeal Gonorrhea
Ocular Gonorrhea
Gonorrhea in Pregnant Women, Neonates, and Children
Gonococcal Arthritis (DGI)
Menstruation is a risk factor for dissemination, and two-thirds cases are in women
Bacteremic stage and a joint-localized stage with suppurative arthritis
D/D; reactive arthritis AND septic arthritis
Rapid diagnosis - Gram's staining of urethral exudates
Nucleic acid probe tests are being substituted for culture, BUT NOT
LEGALLY
Single IM dose of the third-generation cephalosporin, mainstay of
therapy
OR azithromycine (1g single dose)
Because co-infection with C. trachomatis occurs frequently, initial
treatment regimens must also incorporate an agent
DGI require higher dosages and longer durations of therapy
All persons who experience more than one episode of DGI should be
evaluated for complement deficiency
Condoms, if properly used, effective protection against the transmission
and acquisition of gonorrhea
Patients should be instructed to abstain from sexual intercourse until
therapy is completed and until they and their sex partners no longer
have symptom
HAEMOPHILUS
Grows both aerobical y (requires two factors: hemin (X factor) and nicotinamide
adenine dinucleotide (V factor) and anaerobical y as coccobacil i
Among a-f serotypes, Type b and nontypable strains are the most relevant strains
clinically
Spread by airborne droplets or by direct contact with secretions or fomites
Colonization with nontypable is a dynamic process and are primarily mucosal
pathogens (EARS, BRONCHUS)
Hib strains cause systemic disease by invasion and hematogenous spread from
the respiratory tract
DISEASES BY Hib; Meningitis, Epiglottitis (later age child), Cellulitis, Pneumonia
Nontypable H. influenzae is the most common bacterial cause of exacerbations
of COPD, Other diseases: otitis media, puerperal sepsis, sinusitis, etc
Recovery of the organism in culture is most reliable diagnostic method
Initial therapy for meningitis due to Hib should consist of a cephalosporin
Hib conjugate vaccine to all child and chemoprophylaxis with rifampin
A probable diagnosis of Chancroid
can be made when the following criteria
are met:
(1) one or more painful genital ulcers;
(2) no evidence of Treponema pallidum
infection;
(3) a typical clinical presentation for
chancroid;
(4) a negative test for herpes simplex virus in
the ulcer exudate
Sexually transmitted disease
characterized by genital ulceration and
inguinal adenitis
Associated with HIV infection
Treated with single dose of azithromycin or
ceftriaxone
HACEK organisms
Group of fastidious, slow-growing, gram negative bacteria
whose growth requires an atmosphere of carbon dioxide
Species belonging to this group include several
Haemophilus species, Aggregatibacter (formerly
Actinobacil us) species, Cardiobacterium hominis, Eikenel a
corrodens, and Kingel a kingae
HACEK bacteria normally reside in the oral cavity
The clinical course of HACEK endocarditis tends to be
subacute, particularly with Aggregatibacter or
Cardiobacterium, However, K. kingae endocarditis may
have a more aggressive presentation
LEGIONELLA (IC pathogen)
Legionellosis refers to the two clinical syndromes caused by bacteria of the
genus Legionella
Pontiac fever (IP- 24-48h) is an acute epidemic, febrile, self-limited il ness that has been
serological y linked to Legionel a species, whereas
Legionnaires' disease (IP- 2-10d) is the designation for pneumonia caused by these
species
Species L. pneumophila causes 80?90% of human infections
Natural habitats for L. pneumophila are aquatic bodies
Factors known to enhance colonization include warm temperatures (25??42?C)
and the presence of scale and sediment; The presence of symbiotic
microorganisms, including algae, ameba, ciliated protozoa, and other water-
dwelling bacteria, promotes the growth of Legionella
Multiple modes of transmission including aspiration, aerosolization, and direct
instillation into the lungs during respiratory tract manipulations
Incidence depends on the degree of contamination of the aquatic reservoir,
the immune status of the persons exposed to water from that reservoir, the
intensity of exposure, and the availability of specialized laboratory tests
Dif erential diagnosis of atypical pneumonia should be considered
Legionella cultures - best
Legionella urinary antigen test ? highly specific (for L. pneumophila serogroup 1)
Direct fluorescent antibody (DFA) staining
Antibody testing
Macrolides (especial y azithromycin) and the respiratory quinolones are now the
antibiotics of choice for 10-14 days
For critically ill patients, the authors use combination regimens of azithromycin, a
quinolone, and/or rifampin
Routine environmental culture of hospital water supplies (from cold-water taps,
hotwater taps, the hot-water recirculating line, and water-storage tanks) for
Legionella is recommended as an approach to the prevention of hospital-acquired
Legionnaires' disease
Copper-silver ionization is a reliable method for eradication
BORDETELLA (IC pathogen)
Pertussis ("whooping cough"/ "the 100-day cough")is an acute infection of the
respiratory tract caused by Bordetella pertussis
Cyclical outbreaks every 3?5 years, can affect people of all ages, However,
Severe morbidity and high mortality rates, are restricted almost entirely to
infants
B. pertussis infects only humans, B. parapertussis causes a milder illness; and
rarely by B. holmesii, and B. bronchiseptica
Most important virulence factor is pertussis toxin, others are filamentous
hemagglutinin, pertactin, Fimbriae, tracheal cytotoxin, adenylate cyclase toxin,
dermonecrotic toxin, and LOS
Pathogenesis is unknown after attachment of the organism to the ciliated
epithelial cells of the nasopharynx
IP- 7?10 DAYS
Prolonged coughing illness with clinical manifestations that vary by age
Catarrhal phase, 1-2WKS, (indistinguishable from the common Cold)evolves into the
paroxysmal phase, 2-4WKS, (the cough becomes more frequent and spasmodic with
repetitive bursts of 5?10 coughs, often within a single expiration, episode may be terminated
by an audible whoop, which occurs upon rapid inspiration against a closed glottis at the end
of a paroxysm), Later into convalescent phase, 4-12WKS, (gradual resolution of coughing
episodes)
Vomiting with cough is the best predictor of pertussis as the cause of prolonged cough in
adults
Pneumothorax, severe weight loss, inguinal hernia, rib fracture, carotid artery aneurysm, and
cough syncope ? COMPLICATIONS
Laboratory confirmation (Culture of nasopharyngeal secretions ) should be attempted in all
cases, nowadays being replaced by PCR
Lymphocytosis (an absolute lymphocyte count of >1?10,000/cc ) is common
Pertussis should be suspected when any patient has
a cough that does not improve within 14 days,
a paroxysmal cough of any duration,
a cough followed by vomiting (adolescents and adults), or
any respiratory symptoms after contact with a laboratory-confirmed case of pertussis
Purpose of antibiotic therapy for pertussis is to eradicate the infecting bacteria from the
nasopharynx; therapy does not substantially alter the clinical course unless given early in the
catarrhal phase; Macrolide antibiotics are the drugs of choice
BRUCELLA (undulant fever, IC organism))
Brucellosis is a bacterial zoonosis transmitted directly or indirectly to humans from
infected animals, predominantly domesticated ruminants and swine
B. melitensis, B. abortus, B. suis, B. canis, B. neotomae, B. ceti, and B.
pinnipedialis
Brucellosis may be acquired by ingestion, inhalation, or mucosal or
percutaneous exposure
IP- 1 week to several months
Pathogenesis is unknown; The organism is a "stealth" pathogen who avoids
triggering innate immune responses and that permit survival within monocytic
cells
Brucellosis almost invariably causes fever; dif ers from other fevers,
(1) Left untreated, the fever of brucel osis shows an undulating pattern that persists for
weeks before the commencement of an afebrile period that may be fol owed by
relapse
(2) The fever of brucel osis is associated with musculoskeletal symptoms and signs in
about one-half of all patients
Often fits one of three patterns:
febrile illness that resembles typhoid but is less severe;
fever and acute monoarthritis, typically of the hip or knee, in a young
child;
long-lasting fever, misery, and low-back or hip pain in an older man
Diagnosis must be based on a history of potential exposure, a
presentation consistent with the disease, and supporting laboratory
findings (Culture, PCR, serology)
Gold standard for the treatment of brucellosis in adults is IM streptomycin
(0.75?1 g daily for 14?21 days) together with doxycycline(100 mg twice
daily for 6 weeks)
Chemoprophylaxis; the administration of rifampin plus doxycycline for 3
weeks after a low-risk exposure (e.g., an unspecified laboratory accident)
and for 6 weeks after a major exposure to aerosol or injected material
Relapse occurs in up to 30% of poorly compliant patients
FRANCISELLA
Tularemia is a zoonosis caused by Francisella tularensis
Humans of any age, sex, or race are universally susceptible to this systemic
infection
It is primarily a disease of wild animals and persists in contaminated
environments, ectoparasites, and animal carriers
Human infection is incidental and usually results from interaction with biting or
blood-sucking insects, contact with wild or domestic animals, ingestion of
contaminated water or food, or inhalation of infective aerosols
Characterized by an ulcerative lesion at the site of inoculation, with regional
lymphadenopathy and lymphadenitis
Systemic manifestations, including pneumonia, typhoidal tularemia, meningitis,
and fever without localizing findings may occur
The diagnosis of tularemia is most frequently confirmed by agglutination testing
Only aminoglycosides, tetracyclines, chloramphenicol, and rifampin are
currently approved (7?10 days)
YERSINIA
Plague is a systemic zoonosis caused by Yersinia pestis
It predominantly affects small rodents and is usual y transmitted to humans by an
arthropod vector (the flea), Less often, contact with animal tissues or respiratory
droplets
Patients can present with the bubonic, septicemic, or pneumonic form of the
disease
Although there is concern among the general public about epidemic spread of
plague by the respiratory route, this is not the usual route of plague transmission
Initial presumptive diagnosis followed by reference laboratory confirmation
10-day course of antimicrobial therapy is recommended
Postexposure antimicrobial prophylaxis lasting 7 days is recommended following
household, hospital, or other close contact with persons with untreated
pneumonic plague. (Close contact is defined as contact with a patient at <2 m.)
Yersiniosis is a zoonotic infection with an enteropathogenic Yersinia species,
usually Yersinia enterocolitica or Y. pseudotuberculosis
BARTONELLA
Clinical presentation generally depends on both theinfecting Bartonella
species and the immune status of the infected individual
Usually a self-limited illness, cat-scratch disease (CSD) has two general clinical
presentations;
Typical CSD, the more common, is characterized by subacute regional
lymphadenopathy;
atypical CSD is the col ective designation for numerous extranodal manifestations
involving various organs.
B. henselae is the principal etiologic agent of CSD
A history of cat contact, a primary inoculation lesion, and regional
lymphadenopathy are highly suggestive of CSD
Azithromycin may be given, but limited role
Suppurative nodes should be drained by large-bore needle aspiration and not
by incision and drainage in order to avoid chronic draining tracts
Thank you
This post was last modified on 05 April 2022