MEDICINE
current biofilm on the foreign object in less than 24
hours.7
Recognising Biofilms
Biofilms tend to develop in the urinary tract—but how
do we detect the presence of a biofilm?
Unfortunately, biofilms are difficult to detect. Visualisation techniques used in research include scanning
electron microscopy or confocal laser microscopy,
neither of which is readily available or useful to detect
infection in a live animal. A polymerase chain reaction
(PCR) test to search for a biofilm-specific gene is in
development but is not yet commercially available.8
How Biofilms Affect the Urinary Tract
Biofilms tend to develop in the urinary tract—but how do we
detect the presence of a biofilm? Unfortunately, biofilms are
difficult to detect. Visualisation techniques used in research
include scanning electron microscopy or confocal laser microscopy, neither of which is readily available or useful to
detect infection in a live animal. A polymerase chain reaction
(PCR) test to search for a biofilm-specific gene is in development but is not yet commercially available.8
Suspect the presence of a biofilm under the following conditions:
• Any chronic urinary tract infection, especially when the
patient presents with a low bacterial cell count.
• Relapses occur after theoretically successful treatment.
• Antibiotic use fails to clear signs in
culture-directed treatment.
• Any catheter-associated infection.5,9
While a foreign object is not necessary, the presence greatly increases
the likelihood of biofilm development.
• Urine culture is negative but the patient responds to antimicrobial treatment.
Treatment
If a biofilm infection is suspected,
treatment strategies include prompt
removal of implants or foreign material
in combination with appropriate antimicrobial therapy. There is no perfect
treatment strategy, but options include
prolonged antibiotic use (≥6 weeks
[this is a highly empirical therapy unsupported by clinical evidence]), higher
antibiotic dosages, and using a combination of antibiotics.6,9 Research suggests that β-lactams and aminoglycosides may help prevent the formation
of a biofilm but are less useful once a
colony has become established; fluoroquinolones, on the other hand, are
better able to penetrate an “older” biofilm colony (ie, a well-established colony that may have secondary bacteria
communities and decreased frequency of dividing and growing).1
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Issue 04 | JULY 2015 | 10
Although there is no clinical evidence
to support their effect on the biofilm,
the instillation of commensal bacteria shows promise in the treatment
of some infections (eg, commensal
strains of Staphyloccocus epidermidis
that secrete the EspA protease to prevent biofilm formation and nasal colonisation by S aureus in humans). These
low-virulence bacteria cause passive
interference with more pathogenic
strains, and this strategy has shown
success in human cases of recurrent
UTI and vaginitis (eg, with Lactobacillus
spp).4,10 Research in human medicine is