Page 195 - Textbook of Pathology, 6th Edition

follicles. Impetigo is yet another staphylococcal skin infection 179
common in school children in which there are multiple
pustular lesions on face forming honey-yellow crusts. Breast
abscess may occur following delivery when staphylococci are
transmitted from infant having neonatal sepsis or due to
stasis of milk. CHAPTER 7
2. Infections of burns and surgical wounds. These are quite
common due to contamination from the patient’s own nasal
secretions or from hospital staff. Elderly, malnourished, obese
patients and neonates have increased susceptibility.

3. Infections of the upper and lower respiratory tract.
Small children under 2 years of age get staphylococcal
infections of the respiratory tract commonly. These include
pharyngitis, bronchopneumonia, staphylococcal
pneumonia and its complications.
4. Bacterial arthritis. Septic arthritis in the elderly is caused
Figure 7.3 Marked peripheral blood lymphocytosis in whooping by Staph. aureus.
cough. Infectious and Parasitic Diseases
5. Infection of bone (Osteomyelitis). Young boys having
or anal intercourse and by autoinoculation. The incubation history of trauma or infection may develop acute
period varies from 2 to 4 weeks. Initially, the lesion is in the staphylococcal osteomyelitis (Chapter 28).
form of a papule, a subcutaneous nodule or an ulcer. Within
a few weeks, it develops into a raised, soft, painless, reddish 6. Bacterial endocarditis. Acute and subacute bacterial
ulcer with exuberant granulation tissue. Depending upon endocarditis are complications of infection with Staph. aureus
and Staph. epidermidis (Chapter 16).
whether the individual is heterosexual or homosexual, the
lesions are located on the penis, scrotum, genito-crural folds 7. Bacterial meningitis. Surgical procedures on central
and inguinal folds, or in the perianal and anal area respecti- nervous system may lead to staphylococcal meningitis
vely. Regional lymphadenopathy generally does not occur. (Chapter 30).

Microscopically, the margin of the ulcer shows epithelial
hyperplasia. The ulcer bed shows neutrophilic abscesses.
The dermis and subcutaneous tissues are infiltrated by
numerous histiocytes containing many bacteria called
Donovan bodies, and lymphocytes, plasma cells and
neutrophils. These organisms are best demonstrated by
silver impregnation techniques.

STAPHYLOCOCCAL INFECTIONS
Staphylococci are gram-positive cocci which are present
everywhere—in the skin, umbilicus, nasal vestibule, stool
etc. Three species are pathogenic to human beings: Staph.
aureus, Staph. epidermidis and Staph. saprophyticus. Most
staphylococcal infections are caused by Staph. aureus.
Staphylococcal infections are among the commonest
antibiotic-resistant hospital-acquired infection in surgical
wounds.
A wide variety of suppurative diseases are caused by
Staph. aureus which includes the following (Fig. 7.4):
1. Infections of skin. Staphylococcal infections of the skin
are quite common. The infection begins from lodgement of
cocci in the hair root due to poor hygiene and results in
obstruction of sweat or sebaceous gland duct. This is termed
folliculitis. Involvement of adjacent follicles results in larger
lesions called furuncle. Further spread of infection
horizontally under the skin and subcutaneous tissue causes
carbuncle or cellulitis. Styes are staphylococcal infection of the
sebaceous glands of Zeis, the glands of Moll and eyelash Figure 7.4 Suppurative diseases caused by Staphylococcus aureus.