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Common Bacterial Infections in Children 95

response, which includes increased blood flow in the tissue and attrac- Diagnosis
tion of inflammatory cells, especially leukocytes. The capillary becomes The diagnosis of a surface abscess is obvious by its classic appearance, local
porous, and plasma proteins, especially fibrinogen, is released into the pain, redness, tenderness, and central yellow punctum, from which it may
tissue spaces. Fibrinogen forms a fibrin plug to restrain the invading drain if not treated adequately. An internal abscess may be difficult to diag-
organism. The neutrophils start phagocytosis of bacteria, release proteo- nose due to overlapping symptoms with the preceding illness. The key diag-
lytic enzymes, and ultimately undergo necrosis. The abscess cavity is nostic features are persistent fluctuant pyrexia, chills, and lack of appetite.
isolated from the surrounding tissue by the formation of pyogenic mem- Treatment
brane. The proteolytic enzymes digest the dead tissue and give liquid Treatment of abscesses anywhere in the body is drainage. This holds
consistency to pus. With the progression of the inflammatory process, true for most abscesses except for small lesions. If not drained in time
granulation tissue is formed around the abscess cavity. The granulation an abscess tends to find its own path in the area of least resistance. It
tissue helps to prevent the spread of bacteria and inflammatory processes may therefore drain itself externally onto the surface, or internally as
into the surrounding tissue, but it also prevents adequate concentration seen in subcutaneous tissue abscesses, or internally into other hollow
of antibiotic penetration into the tissue, making antibiotics less effective. organs such as the gut or urinary bladder. Spontaneous drainage of
Bacteria have a limit to proliferation, and after the maximum number an abscess may have serious consequences, and every effort shall be
of bacteria per unit volume has been achieved, further proliferation is made to control infection and drain the abscess surgically. This may be
stopped. Bacteria become less active and thus less vulnerable to anti- achieved for surface abscesses by making an incision, or for internal
biotics. The production of various enzymes, such as beta-lactamase, abscesses, by percutaneous drainage by ultrasound or computed tomog-
also cause a breakdown of the antibiotics. As the inflammatory process raphy (CT) guidance. In some cases, an internal abscess will need
progresses, macrophages appear in the inflammatory zone and start the exploration if it is not in an accessible area for percutaneous drainage.
process of demolition. These macrophages then replace the neutrophils The surface abscess cavity should not be closed after drainage, as pus
within the pyogenic membrane and ultimately start healing by secondary continues to form for days and weeks, and even after adequate drainage
intention to leave a residual scar.
this may cause a recurrence in closed wounds. Repeated drainage of an
Locations internal abscess may be required. All abscesses must be sent for culture
Abscesses may form anywhere in the body (Figures 15.2 and 15.3). The and sensitivity to ensure proper antibiotic coverage after drainage.
main sources of abscess formation are open or penetrating wounds, local The role of antibiotics in an abscess is to control spread of infection.
extension from an adjacent focus of infection, haematogenous spread, or Once the abscess has been drained, the patient usually recovers rapidly,
infections via lymph vessels and lymph nodes. The infecting organism but antibiotics should be continued to prevent the spread of infection,
varies according to the site and source of infection. Most abscesses on especially in debilitated and immunocompromised patients.
the skin and subcutaneous tissue are caused by Staphylococcus aureus. Intraabdominal Abscess
Causative organisms in deep abdominal abscesses depend upon the Intraabdominal abscesses are commonly seen as a sequel of abdomi-
source of infection. In colon and appendix perforations, the abscess is nal surgery; however, gut conditions, such as Crohn’s disease, ulcer-
usually polymicrobial and may cause fulminant infection or serious ative colitis, and abdominal malignancies, may also cause a primary
necrotising fasciitis. This form of infection is not common in the paedi- intraabdominal abscess. Abdominal abscesses are also seen after gut
atric population; however, malnourished, immunocompromised children perforations secondary to trauma, penetrating injuries, and infective pro-
and those on chemotherapy are at a high risk of such infections.
cesses such as necrotising enterocolitis, enteric fever, and appendicitis.
Immunocompromised patients are at a high risk of developing abdominal
abscesses. In these patients, due to their altered immunological response,
gut flora may grow rapidly and bacterial translocation may cause
intraloop abscesses. The clinical features of intraabdominal abscesses
depend upon the causative factors. In postoperative cases and bowel
resection, the patient may initially show good recovery, but between 5
and 10 day postoperative, the patient develops intermittent fever, local
tenderness, abdominal distention, and a palpable lump in the abdomen.
In pelvic abscesses, rectal examination will reveal a tender bulge ante-
riorly. Subphrenic abscesses may also cause respiratory symptoms and
breathing difficulty. Abscesses have the history of incidence secondary
to penetrating injury or abdominal surgery, with or without gut perfora-
tion. Patients with inflammatory bowel disease (e.g., ulcerative colitis
Figure 15.3: Axillary abscess. and Crohn’s disease) will experience a deterioration in their general
condition. Plain abdominal x-ray will show dilated gut loops due to the
ileus and elevation of the hemidiaphragm in subphrenic collections.
Ultrasonography will show the size and dimension of collection, but an
abdominal CT scan may be required to evaluate the exact anatomy of the
abscess cavity and its extension. Most localised intraabdominal abscesses
may now be treated with ultrasound- or CT-guided aspiration along with
broad-spectrum antibiotics. Open external drainage may also be required
in patients who fail to improve after percutaneous aspiration or those
forming repeated abscesses.
Cold Abscess
Cold abscess is the name given to a specialised form of abscess caused
by Mycobacterium tuberculosis. Unlike acute pyogenic abscess, cold
abscess has an insidious onset. It usually affects the neck area but may
Figure 15.2: Groin abscess.
form abscess in areas such as the spine and psoas muscle. The patient