Jan, 2001. Staphylococcus aureus antibiotic prophylaxis [online]. Seacroft and St James's University Hospitals, Leeds, UK. Available from http://www.cysticfibrosismedicine.com

Use of antibiotics in the U.K. has been recently reviewed (Elborn et al, 1999). If S. aureus grows repeatedly from the sputum or throat swabs, antibody studies suggest that it is almost certainly present in the lower airways (Strandvik, 1990). Also comparison of cultures from the throat and bronchial tubes of the same patients supports this finding. Our present policy is to recommend long term prophylactic flucloxacillin (Floxapen) and this is continued indefinitely (50-100mg/kg/day in divided doses to a maximum of 1 gram four times a day in adults). When patients are receiving long term prophylactic flucloxacillin, S. aureus is no longer a significant problem and cultured infrequently (Southern et al, 1993; Littlewood et al, 1995).

A comparison of screened CF infants in East Anglia on long term flucloxacillin or episodic antibiotics from the time of diagnosis showed those on long term flucloxacillin had significantly less cough, fewer S. aureus isolates, less often required in-patient treatment, had shorter hospital admisions and needed fewer courses of additional antibiotics (Weaver et al, 1994). Although the CF Foundation's 4-year trial of cephalexin failed to demonstrate clinical differences between the treated and control children, the treated group had fewer positive cultures for S. aureus, 6% vs 30% but more P. aeruginosa, 25% vs 6% (Stutman & Martell, 1992). A recent systematic review of the diversity of treatments for S. aureus found that anti-staphylococcal treatment achieved sputum clearance of S. aureus and concluded that prophylactic treatment in young children is likely to be of clinical benefit (McCaffery et al, 1999).

Alternative to prophylactic: Some CF clinics (e.g., Copenhagen) do not recommend long term flucloxacillin, but perform regular throat swabs or sputum cultures. Any potentially harmful organisms isolated from the cultures, including S. aureus, are treated with a course of an appropriate antibiotic. Further cultures are taken in two or three weeks to ensure the organism has cleared (Szaff & Hoiby, 1981). A major disadvantage of this approach is that throat cultures are an insensitive method of detecting organisms in the lower airways. Recent studies comparing throat/sputum cultures and cultures obtained at bronchoscopy revealed many potential pathogens in the lower airways which had not been detected by cultures from the upper respiratory tract (Wood, 1989; Ramsey et al, 1991; Armstrong et al, 1995; Armstrong et al, 1996). Also cultures are performed infrequently in some clinics and therefore S. aureus or other pathogens are not identified and thus not treated.

Finally, if S. aureus grows repeatedly from a patient who is considered to be taking long term flucloxacillin one should first confirm that the patient is actually taking the drug. Another anti-staphylococcal antibiotic should be added for 2 weeks, e.g., clindamycin, fucidin, azithromycin or erythromycin. Before accepting that it is not possible to eradicate S. aureus the patient should receive a 2 week course of intravenous antibiotics which would include clindamycin and/or flucloxacillin. Some older patients have entrenched S. aureus for many years. It is reasonable to treat them with long term flucloxacillin to minimise tissue damage. Some clinics will not specifically treat the S. aureus unless its appearance is associated with an obvious change in symptoms and signs. In Leeds we do not agree with that policy. No clinical trial has yet answered the question whether prophylactic or intermittent anti-staphylococcal therapy results in improved lung function tests or chest x-rays, an increase in bacterial resistance or earlier P. aeruginosa infection (McCaffrey et al, 1999).

For more details see CF (UK) Trust antibiotic consensus section

References

Armstrong DS, Grimwood K, Carzino R, Carlin JB, Olinsky A, Phelan PD. Lower respiratory tract infection and inflammation in infants with newly diagnosed cystic fibrosis. BMJ 1995; 310: 1571-1572

Armstrong DS, Grimwood K, Carlin JB, Carzino A, Phelan PD. Bronchoalveolar lavage and oropharyngeal cultures to identify lower respiratory pathogens in infants with cystic fibrosis. Pediatr Pulmonol 1996; 21: 267-275

Elborn JS. Treatment of Staphylococcus aureus in cystic fibrosis. Thorax 1999; 54: 377-379 Elborn JS. Treatment of Staphylococcus aureus in cystic fibrosis. Thorax 1999; 54: 377-379

Littlewood JM, Littlewood AE, McLaughlin S, Shapiro L, Connolly S. 20 years continuous neonatal screening in one hospital; progress of the 37 patients and their families. Pediatr Pulmonol 1995; Suppl 12: 374

McCaffery K, Olver RE, Franklin M, Mukhopadhyay S. Systemic review of anti-staphylococcal antibiotic therapy in cystic fibrosis. Thorax 1999; 54: 380-383

Ramsay BW, Wentz KR, Smith AL, Richardson M, Williams-Warren J, Hedges DL, Gibson R, Redding GJ, Lent K, Harris K. Predictive value of oropharyngeal cultures for identifying lower airway bacteria in cystic fibrosis patients. Am Rev Respir Dis 1991; 144: 331-337

Southern KW, Littlewood AE, Littlewood JM. The prevalence and significance of chronic Staphylococcus aureus infection in patients with cystic fibrosis on long term flucloxacillin. In: Escobar H, Baquero CF, Svarez L, editors. Clinical Ecology of Cystic Fibrosis. Elsevier Science Publ. 1993: 129-130.

Strandvik B, Hollsing A, Mollby R, Granstrom M. Anti-staphylococcal antibodies in cystic fibrosis. Infection 1990; 18: 170-172

Stutman HR, Marks MI. Antibiotic Prophylaxis Study Group. Cephalexin prophylaxis in newly diagnosed infants with cystic fibrosis. Sixth Annual North American Cystic Fibrosis Conference; 1992 Washington DC

Szaff M, Hoiby N. Antibiotic treatment of S. aureus infection in cystic fibrosis. Monogr Paediatr 1981; 14: 108 -114

Wood RE, Piazza F. Survival in cystic fibrosis: correlation with treatment in three cystic fibrosis centres. 10th International Cystic Fibrosis Congress, Sydney 1988. Excerpta Medica Asia Pacific Services, 74, p79

Weaver LT, Green MG, Nicholson K, Mills J, Heeley ME, Kuzemko JA et al. Prognosis in cystic fibrosis treated with continuous flucloxacillin from the neonatal period. Arch Dis Child 1994; 70: 84-89

Copyright © cysticfibrosismedicine