This interim guidance was prepared by a Health Protection Agency (HPA) Working Group and is based on a review of the literature and experiences of colleagues in the UK, Europe and the USA. This guidance will be revisited following review of a number of recent cases in the UK.
A new pattern of disease due to Panton - Valentine Leukocidin (PVL) - positive strains of Staphylococcus aureus is emerging in the UK and world-wide. PVL is a toxin, which destroys white blood cells and is carried by <2% of clinical isolates of S. aureus [1]. PVL can be detected in both meticillin sensitive S. aureus (MSSA) and meticillin resistant S. aureus (MRSA) [1]. To date the majority of isolates causing infection in the UK have been MSSA. Community-associated MRSA (CA-MRSA) are more likely to produce PVL than hospital-associated MRSA. PVL-positive S. aureus are normally associated with necrotising pyogenic cutaneous infections and occasionally with cellulitis or tissue necrosis [2]. However, they can cause other severe invasive infections such as septic arthritis, bacteraemia, purpura fulminans [3] or community-acquired necrotising pneumonia [4, 5].
Suspect PVL-associated staphylococcal infection if a patient has recurrent furunculosis or abscesses, especially if in a high risk group e.g. participants in close-contact sports, the military or those in residential homes.
Abscesses should be drained surgically and then treated with systemic anti-staphylococcal antibiotics - choice depending on susceptibility testing.
Currently, most UK PVL-positive Staph aureus strains are susceptible to flucloxacillin and usually sensitive to erythromycin and clindamycin. Consider combinations of doxycycline and rifampicin for CA-MRSA.
Patients should be screened (nose, throat, perineum, axilla, skin lesions) for S. aureus carriage and decolonisation regimens such as those used for MRSA decolonisation may need to be used to eradicate skin or upper respiratory carriage [6].
N.B. Screening swabs should be cultured on non-selective media (e.g. blood agar) to ensure the recovery of S. aureus independent of their meticillin susceptibility.
PVL - positive strains of S. aureus have been associated with a rapidly progressive, haemorrhagic, necrotising community-acquired pneumonia in young immunocompetent patients, and a high fatality rate [4]. Most patients developing necrotising pneumonia have no history of skin sepsis but commonly have a preceding 'flu-like' illness.
Early clinical diagnosis is difficult but essential for survival. Typically the following features in a previously fit young patient suggest the diagnosis. In general practice, particularly haemoptysis, hypotension and severe sepsis following a 'flu like' illness warrants prompt referral to hospital. Once admitted, the constellation of findings strongly suggests the diagnosis:
N.B. The CURB score [7] may be misleadingly low in young adults on admission.
There is a wide range of potentially useful antibiotics for treatment. It is important to check the susceptibility of individual isolates. Several publications have reported the value of combination therapy.
Combinations including vancomycin, clindamycin, linezolid, rifampicin and/or co-trimoxazole in high doses have been used [4,5,8,9].
Vancomycin should not be used alone [10]. Intravenous flucloxacillin (2gm 4-6 hourly) may be useful for bactericidal action in combination with linezolid (600 mg bd iv) or rifampicin (300 mg bd iv).
Linezolid can be used to cover MRSA pending antibiotic susceptibility results; clindamycin (1.2 gm qds), like linezolid, has the added advantage of suppressing toxin production.
Surgical masks should be worn during intubation and physiotherapy. Closed tracheal suction should be used since secondary cases may occur.
Screening (nose, throat, perineum, axilla, skin lesions) of close contacts for carriage of PVL-positive S. aureus [6]. See note above on screening swabs.
IVIG should be considered in addition to intensive care support and high dose antibiotic therapy because of high mortality [4]. The dosage of 2g/kg of IVIG recommended in streptococcal toxic shock syndrome may be useful for PVL-positive S. aureus infections, neutralising exotoxins and superantigens [10,11,12].
Isolates of S. aureus from cases which may be PVL - related (including community - acquired skin infections or pneumonia) should be sent to Dr Angela Kearns at the HPA Laboratory of Healthcare Associated Infection (LHCAI) at Colindale, telephone 0208 327 7227.
Dr Christine McCartney (Chair), Interim Deputy Director, HPA Centre for Infections, Colindale.
Prof. Barry Cookson, Director Laboratory of Healthcare Associated Infections, Centre for Infections, Colindale.
Dr David Dance, Regional Microbiologist, HPA, South West.
Dr Chris Day, Consultant in Intensive Care, Royal Devon and Exeter Hospital, Exeter.
Prof. Brian Duerden, Inspector of Microbiology and Infection Control.
Dr Tony Elston, Consultant Microbiologist, Colchester General Hospital, Colchester.
Dr Angela Kearns, Staphylococcal Reference Unit, Laboratory of Healthcare Associated Infection, HPA Centre for Infections, Colindale.
Dr Marina Morgan, Consultant Microbiologist, Royal Devon and Exeter Hospital, Exeter.