edited_Taccetti_edit.qxp 4/2/09 12:13 pm Page 92
Bacterial Infections
Table 1: Drugs and Dosages for the Most Frequently Used Anti-MRSA Therapy in Cystic Fibrosis Patients
(assuming normal renal function)
5,6,9,50,511
Antibiotic Administration Route Dosage Number of Daily Administrations
Sodium Fusidate Oral <5 years 250mg/day 3
5–12 years 500mg/day
>12 years 750mg/day
Rifampin Oral, IV 15mg/kg/day 2
Vancomycin IV 40mg/kg/day 3
Teicoplanin IV 10mg/kg every 12 hours for 3 doses and then 1
10mg/kg/day as single doses
Linezolid Oral, IV (<5 years) 30mg/kg/day 3
Linezolid Oral, IV (>5 years) 20mg/kg/day 2
Ciprofloxacin Oral 20–30mg/kg/day 2
Ciprofloxacin IV 15–30mg/kg/day 2
Tobramycin IV 10mg/kg/day 3
TMP-SMX Oral Trimethoprim 8–10mg/kg/day 2
TMP-SMX IV Trimethoprim 10–20mg/kg/day 4
Minocycline Oral, IV 4mg/kg/day 2
Doxycycline Oral 4.4mg/kg/day 2
Clindamycin oral 20–30mg/kg/day 3–4
IV = intravenous; TMP-SMX = trimethoprim–sulfamethoxazole.
does not seem to be significantly associated to a worsening of the patient’s observation are not totally clear, but may be due to progressive structural
clinical condition, whereas other studies have shown that the presence of damage to the lungs caused by inflammation and chronic infection and the
the germ is associated with a more rapid decline in forced expiratory volume low sensitivity of FEV
1
as a marker of lung pathology in adults. The
in one second (FEV
1
) and with a higher percentage of hospitalisation and Dasembrook et al. study, although carried out in a large number of
greater use of antibiotics.
11,12,39–42
patients, does not provide indications about the molecular characteristics
of MRSA or the role of PVL virulence factor, and does not differentiate
Until now the difficulty in attributing a proper pathogenic role to MRSA in between the roles of CA-MRSA and HA-MRSA.
11
Altogether, these data
CF patients was due to multiple factors. Many patients present with present a peculiar picture of MRSA infection in CF patients. The potential
pulmonary infections due to polymicrobial flora, so it is problematic to negative effect of MRSA on pulmonary function in CF has been
attribute an exact pathogenic role to a single pathogen isolated in the demonstrated in ample numbers of patients, but further studies are
airways. Many studies on MRSA published to date are cross-sectional or needed to verify possible diverse pathogenic effects of MRSA on the lung
brief and conducted on limited numbers of patients.
12,14,39,42–44
Miall et al., in relation to different molecular characteristics of MRSA strains. Currently,
studying a limited number of children infected with MRSA, found a infection or colonisation with MRSA is not considered an absolute
deterioration in height, weight and body mass index in the MRSA group.
12
contraindication for organ transplantation.
46
Compared with the control group, these patients also required a greater
use of antibiotics. Medical Therapy
Obviously, it is best if CF patients do not contract MRSA infection, because
Ren et al., in a study on a large number of patients, observed that those it reduces their antibiotic therapy options and possibly causes deterioration
harbouring MRSA were more frequently hospitalised, necessitating a higher in their lung function. As for other pathogens, eradicating MRSA from the
use of antibiotics, and had lower FEV
1
values compared with a control group airways of patients affected by CF (see Table 1) can theoretically benefit the
who had methicillin-susceptible S. aureus (MSSA).
42
Also in this case, the patient and reduce the possibility of diffusion of this bacteria.
2
cross-sectional characteristics of the study do not permit us to assign an
absolute causal role between the presence of MRSA in the airways and A combination therapy of fusidic acid and rifampin for six months has been
pulmonary function. Because some of the pathogenic roles of MRSA on demonstrated to be efficacious in the eradication of MRSA from the airways
pulmonary function in CF patients could be attributable to virulence factors in five of seven CF adults in one study.
44
Treatment schedules with the same
produced by the germ itself, Elizur et al. recently speculated on the role of drugs, in combination with topical 2% mupirocin to the anterior nostrils for
the PVL virulence factor.
14
In one study conducted on a limited number five days and, possibly, repeated administrations, have been demonstrated
of patients, those with newly acquired PVL-positive MRSA required more to be effective.
47
Nebulised and topical vancomycin has been shown to be
frequent hospitalisation for pulmonary exacerbations. They presented with a efficacious in clearing MRSA.
39
The use of nebulised vancomycin has
higher number of pulmonary infiltrates as seen by chest X-ray and had more nevertheless been criticised because of the possibility of the selection of
rapid FEV
1
decline compared with those harbouring PVL-negative MRSA.
45
strains resistant to the drug, so this mode of administration is not included
in the guidelines regarding vancomycin.
48
Recently, the possibility of
Another clinical study recently published on 1,732 North American patients eradicating MRSA with oral linezolid, a bacteriostatic agent of the
with persistent MRSA infection in follow-up for 3.5 years indicated a more oxazolidinone family, has been reported.
10
A European consensus report
rapid FEV
1
decline (average decline 2.06% predicted/year) in patients eight suggests that it is important to try to eradicate MRSA, but the evidence on
to 21 years of age compared with those patients not harbouring MRSA which the recommendations are based is not derived from randomised
(average decline 1.44% predicted/year).
11
The effect of MRSA on the FEV
1
clinical studies.
2
Other authoritative publications reinforce suggestions
decline was not clinically significant in adults. The reasons for this regarding MRSA eradication.
24
92 EUROPEAN INFECTIOUS DISEASE
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