Staphylococcal Disease

Clinical Description

Identification

Staphylococci produce a variety of syndromes, with clinical manifestations ranging from a single pustule to sepsis and death. A pus-containing lesion (or lesions) is the primary clinical finding, and abscess formation is the typical pathological manifestation; production of toxins may also lead to staphylococcal diseases, as in toxic shock syndrome. Virulence of bacterial strains varies greatly.

Staphylococcal disease has different clinical and epidemiological patterns in the general community, in newborns, in menstruating women and among hospitalized patients; each will be presented separately. Staphylococcal food poisoning, an intoxication and not an infection, is not discussed here.

Staphylococcal Disease on Hospital Medical and Surgical Wards

Lesions vary from simple furuncles or stitch abscesses to extensively infected bedsores or surgical wounds, septic phlebitis, acute or chronic osteomyelitis, pneumonia, meningitis, endocarditis or sepsis. Post-operative staphylococcal disease is a constant threat to the convalescence of the hospitalized surgical patient. The increasing complexity of surgical operations, greater organ exposure and more prolonged anesthesia promote entry of staphylococci. Increased use of prosthetic devices and indwelling catheters accounts for increased incidence of nosocomial staphylococcal infections. A toxic state can complicate infection (toxic shock syndrome) if the strain produces toxins (this is an ever-present risk). Frequent and sometimes injudicious use of antimicrobials has increased the prevalence of antibiotic-resistant staphylococci.

Staphylococcal Disease in the Community

The common bacterial skin lesions are impetigo, folliculitis, furuncles, carbuncles, abscesses and infected lacerations. The basic lesion of impetigo is described in section II, 1; a distinctive “scalded skin” syndrome is associated with certain strains of Staphylococcus aureus, which elaborate an epidermolytic toxin. Other skin lesions are localized and discrete. Constitutional symptoms are unusual; if lesions extend or are widespread, fever, malaise, headache and anorexia may develop. Usually, lesions are uncomplicated, but seeding of the bloodstream may lead to pneumonia, lung abscess, osteomyelitis, sepsis, endocarditis, arthritis or meningitis. In addition to primary skin lesions, staphylococcal conjunctivitis occurs in newborns and the elderly. Staphylococcal pneumonia is a well-recognized complication of influenza. Staphylococcal endocarditis and other complications of staphylococcal bacteremia may result from parenteral use of illicit drugs, or nosocomially from intravenous catheters and other devices. Embolic skin lesions are frequent complications of endocarditis and/or bacteremia.

Coagulase-negative staphylococci may cause sepsis, meningitis, endocarditis or urinary tract infections, and are increasing in frequency, usually in connection with prosthetic devices or indwelling catheters.

Staphylococcal Disease in Hospital Nurseries

Impetigo or pustulosis of the newborn and other purulent skin manifestations are the staphylococcal diseases most frequently acquired in nurseries. Characteristic skin lesions develop secondary to colonization of the nose, umbilicus, circumcision site, rectum or conjunctivae. Colonization of these sites with staphylococcal strains is a normal occurrence and does not imply disease.

Lesions most commonly occur in diaper and intertriginous areas, but also elsewhere on the body. They are initially vesicular, rapidly turning seropurulent, surrounded by an erythematous base; bullae may form (bullous impetigo). Rupture of pustules favors their spread. Complications are unusual, although lymphadenitis, furunculosis, breast abscess, pneumonia, sepsis, arthritis, osteomyelitis and others have been reported.

Though uncommon, staphylococcal scalded skin syndrome (SSSS or Ritter disease, pemphigus neonatorum) may occur; clinical manifestations range from diffuse scarlatiniform erythema to generalized bullous desquamation. Like bullous impetigo, it is caused by strains of S. aureus, usually phage type II, which produce an epidermolytic toxin.

Infectious Agents

The most important human pathogen is Staphylococcus aureus. Most strains ferment mannitol and are coagulase-positive. However, coagulase-negative strains are increasingly important, especially in bloodstream infections among patients with intravascular catheters or prosthetic materials, in female urinary tract infections, and in nosocomial infections.

Staphylococcal Disease on Hospital Medical and Surgical Wards and in Hospital Nurseries

Staphylococcus aureus. Resistance to penicillin occurs in 95% of strains and increasing proportions are resistant to semi-synthetic penicillins (e.g. methicillin), aminoglycosides (e.g. gentamicin), and quinolones.

Staphylococcal Disease in the Community

Various coagulase-positive strains of Staphylococcus aureus. Most strains of staphylococci may be characterized through molecular methods such as pulsed-field gel electrophoresis, phage type, or antibiotic resistance profile; epidemics are caused by relatively few specific strains. The majority of clinical isolates of Staphylococcus aureus, whether community- or hospital-acquired, are resistant to penicillin G, and multiresistant (including methicillin-resistant) strains have become widespread. Evidence suggests that slime-producing strains of coagulase-negative staphylococci may be more pathogenic, but the data are inconclusive. S. saprophyticus is a common cause of urinary tract infection in young women.


Diagnosis

Staphylococcal Disease on Hospital Medical and Surgical Wards

Verification depends on isolation of Staphylococcus aureus, associated with a clinical illness compatible with the bacteriological findings.

Staphylococcal Disease in the Community

Diagnosis is confirmed by isolation of the organism.


Epidemiology

Mode of Transmission

Staphylococcal Disease on Hospital and Medical Wards and in the Community

The major site of colonization is the anterior nares; 20%–30% of the general population are nasal carriers of coagulase-positive staphylococci. Autoinfection is responsible for at least one-third of infections. Persons with a draining lesion or purulent discharge are the most common sources of epidemic spread. Transmission is through contact with a person who has a purulent lesion or is an asymptomatic (usually nasal) carrier of a pathogenic strain. Some carriers are more effective disseminators of infection than others. The role of contaminated objects has been overstressed; hands are the most important instrument for transmitting infection. Airborne spread is rare, but has been demonstrated in patients with associated viral respiratory disease.

Staphylococcal Disease in Hospital Nurseries

Primary spread by hands of hospital personnel; rarely airborne.

Incubation Period

Staphylococcal Disease on Hospital and Medical Wards and in the Community

Variable and indefinite.

Staphylococcal Disease in Hospital Nurseries

Commonly 4–10 days; disease may not occur until several months after colonization.

Period of Communicability

As long as purulent lesions continue to drain or the carrier state persists. Autoinfection may continue for the period of nasal colonization or duration of active lesions.

Reservoir

Humans; rarely animals.

Susceptibility

Staphylococcal Disease on Hospital and Medical Wards

Widespread use of continuous intravenous treatment with indwelling catheters and parenteral injections has opened new portals of entry for infectious agents.

Staphylococcal Disease in the Community

Immune mechanisms depend mainly on an intact opsonization/phagocytosis axis involving neutrophils. Susceptibility is greatest among the newborn and the chronically ill. Elderly and debilitated people, drug abusers, and those with diabetes mellitus, cystic fibrosis, chronic renal failure, agammaglobulinemia, disorders of neutrophil function (e.g. agranulocytosis, chronic granulomatous disease), neoplastic disease and burns are particularly susceptible. Use of steroids and antimetabolites also increases susceptibility.

Staphylococcal Disease in Hospital Nurseries

Susceptibility of newborns appears to be general. For the duration of colonization with pathogenic strains, infants remain at risk of disease.


Occurrence

Staphylococcal Disease on Hospital Medical and Surgical Wards

Worldwide. Staphylococcal infection is a major form of acquired sepsis in the general wards of hospitals. Attack rates may assume epidemic proportions, and community spread may occur when hospital-infected patients are discharged.

Staphylococcal Disease in the Community

Worldwide. Highest incidence is in areas where hygiene conditions (especially the use of soap and water) are sub-optimal and people are crowded; common among children, especially in warm weather. The disease occurs sporadically and as small epidemics in families and summer camps, with various members developing recurrent illness due to the same staphylococcal strain (hidden carriers).

Staphylococcal Disease in Hospital Nurseries

Worldwide. Problems occur mainly in hospitals, are promoted by lax aseptic techniques, and are exaggerated by development of antibiotic-resistant strains (hospital strains).


Prevention and Control

Staphylococcal Disease on Hospital Medical and Surgical Wards

1)    Preventive measures:

a)    Educate hospital medical staff to use common, narrow-spectrum antimicrobials for simple staphylococcal infections for short periods, and to reserve certain antibiotics for specific situations (e.g. reserve cephalosporins for penicillin-resistant staphylococcal infections, and vancomycin for beta-lactam resistant staphylococcal infections).

b)    A hospital infection control committee must enforce strict aseptic technique and provide programs to monitor nosocomial infections.

c)    Change sites of IV needle infusions every 48 hours; establish a monitoring system for the examination of central venous lines.

2)    Control of patient, contacts and the immediate environment:

a)    Report to local health authority: Obligatory report of epidemics; no individual case report, Class 4.

b)    Isolation: Whenever staphylococci are known or suspected to be abundant in draining pus or the sputum of a patient with pneumonia, the patient should be placed in a private room. This is not required when wound drainage is scanty, provided an occlusive dressing is used and care is taken in changing dressings to prevent environmental contamination. Health care workers must practice appropriate hand-washing, gloving and gowning techniques.

c)    Concurrent disinfection: See Staphylococcal disease in the community.

d)    Quarantine: Not applicable.

e)    Immunization of contacts: Not applicable.

f)    Investigation of contacts and source of infection: Not practical for sporadic cases.

g)    Specific treatment: Appropriate antimicrobials as determined through antibiotic sensitivity tests. Life-threatening infections should be treated with vancomycin pending test results.

3)    Epidemic measures:

a)    The occurrence of 2 or more cases with epidemiological association is sufficient to suspect epidemic spread, and to initiate investigation.

b)    Review and enforce rigid aseptic techniques.

4)    Disaster implications:

None.

5)    International measures:

WHO Collaborating Centres can provide technical support as required. More information can be found at: http://www.who.int/collaboratingcentres/database/en/

Staphylococcal Disease in the Community

1)    Preventive measures:

a)    Educate the public and health personnel in personal hygiene, especially handwashing and the importance of not sharing toilet articles.

b)    Treat initial cases in children and families promptly.

2)    Control of patient, contacts and the immediate environment:

a)    Report to local health authority: Obligatory report of outbreaks in schools, summer camps and other population groups; also any recognized concentration of cases in the community for many industrialized countries. No individual case report, Class 4.

b)    Isolation: Not practical in most communities; infected people should avoid contact with infants and debilitated people.

c)    Concurrent disinfection: Place dressings from open lesions and discharges in disposable bags; dispose of these in a practical and safe manner.

d)    Quarantine: Not applicable.

e)    Immunization of contacts: Not applicable.

f)    Investigation of contacts and source of infection: Search for draining lesions; occasionally, determination of nasal carrier status of the pathogenic strain among family members or health care workers (as appropriate) is useful.

g)    Specific treatment: In localized skin infections, systemic antimicrobials are not indicated unless infection spreads significantly or complications ensue; local skin cleaning followed by application of an appropriate topical antimicrobial (such as mupirocin, 4 times a day) is adequate. Avoid wet compresses, which may spread infection; hot dry compresses may help localized infections. Incise abscesses to permit drainage of pus and possible removal of foreign bodies. For severe staphylococcal infections, use penicillinase-resistant penicillin; if there is hypersensitivity to penicillin, use a cephalosporin active against staphylococci (unless there is a history of immediate hypersensitivity to penicillin) or a macrolide. In severe systemic infections, choice of antibiotics should be governed by results of susceptibility tests on isolates. Vancomycin is the treatment of choice for severe infections caused by coagulase-negative staphylococci and methicillin-resistant S. aureus; prompt parenteral treatment is important.

Strains of Staphylococcus aureus with high-level resistance to vancomycin and other glycopeptide antibiotics are reported from many countries worldwide. These are usually recovered from patients treated with vancomycin for extended periods (months), and escalate in some healthcare settings.

3)    Epidemic measures:

a)    Search for and treat those with clinical illness, especially those with draining lesions; strict personal hygiene with emphasis on handwashing. Culture for nasal carriers of the epidemic strain and treat locally with mupirocin—and, if unsuccessful, orally administered antimicrobials.

b)    Investigate unusual or abrupt prevalence increases in community staphylococcal infections for a possible common source, e.g. an unrecognized hospital epidemic.

4)    Disaster implications:

None.

5)    International measures:

WHO Collaborating Centres can provide technical support as required. More information can be found at: http://www.who.int/collaboratingcentres/database/en/

Staphylococcal Disease in Hospital Nurseries

1)    Preventive measures:

a)    Use aseptic techniques when necessary, and wash hands before contact with each infant in nurseries.

b)    Personnel with minor lesions (pustules, boils, abscesses, paronychia, conjunctivitis, severe acne, otitis external or infected lacerations) must not be permitted to work in nurseries.

c)    Surveillance and supervision through an active hospital infection control committee, including a regular system for investigating, reporting and reviewing hospital-acquired infections. Illness developing after discharge from hospital must also be investigated and recorded, preferably through active surveillance of all discharged newborns after about 1 month.

d)    Some advocate routine application of antibacterial substances such as gentian violet, acriflavine, chlorhexidine or bacitracin ointment to the umbilical cord stump while in the hospital.

2)    Control of patient, contacts and the immediate environment:

a)    Report to local health authority: Obligatory report of epidemics; no individual case report, Class 4.

b)    Isolation: Without delay, place all known or suspected cases in the nursery on contact isolation precautions.

c)    Concurrent disinfection: See Staphylococcal disease in the community.

d)    Quarantine: Not applicable.

e)    Immunization of contacts: Not applicable.

f)    Specific treatment: Localized impetigo: cleanse skin and apply a topical antibiotic such as mupirocin ointment (4 times a day); widespread lesions may be treated orally with an anti-staphylococcal antimicrobial such as cephalexin or cloxacillin. Serious infections require parenteral treatment. Nasal decontamination with mupirocin is indicated to prevent recurrence.

3)    Epidemic measures:

a)    The occurrence of 2 or more concurrent cases of staphylococcal disease related to a nursery or a maternity ward is presumptive evidence of an outbreak and warrants investigation. Culture all lesions to determine antibiotic resistance pattern and type of epidemic strain. Laboratories should keep clinically important isolates for 6 months before discarding them, so as to support possible epidemiological investigation using antibiotic sensitivity patterns or pulsed-field gel electrophoresis.

b)    In nursery outbreaks, institute isolation precautions for cases and contacts until all have been discharged. Use a rotational system (“cohorting”) where one unit (A) is filled and subsequent babies are admitted to another nursery (B) while the initial unit (A) discharges infants and is cleaned before new admissions. If facilities are present for baby in-rooming, this may reduce risk. Colonized or infected infants should be grouped in another cohort. Assignments of nursing and other ward personnel should be restricted to specific cohorts.

Before admitting new patients, wash cribs, beds and other furniture with an approved disinfectant. Autoclave instruments that enter sterile body sites, wipe mattresses, and thoroughly launder bedding and diapers (or use disposable diapers).

c)    Examine all patient care personnel for draining lesions anywhere on the body. Perform an epidemiological investigation, and if one or more personnel are associated with the disease, culture nasal specimens from them and all others in contact with infants. It may become necessary to exclude and treat all carriers of the epidemic strain until cultures are negative. Treatment of asymptomatic carriers is directed at suppressing the nasal carrier state, usually through local application of appropriate antibiotic ointments to the nasal vestibule, sometimes with concurrent systemic rifampicin for 3–9 days.

d)    Investigate adequacy of nursing procedures, especially availability of handwashing facilities. Emphasize strict handwashing; if facilities are inaccessible or inadequate, consider use of a hand antiseptic agent (e.g. alcohol-based) at the bedside. Personnel assigned to infected or colonized infants should not work with non-colonized newborns.

4)    Disaster implications:

None.

5)    International measures:

WHO Collaborating Centres provide support as required. More information can be found at: http://www.who.int/collaboratingcentres/database/en/

Source: Heymann (Ed.). (2008). Control of Communicable Diseases Manual, 19th edition. Washington, DC: American Public Health Association.

 

Common Disease Taxonomy: