Dr. Kirsner
|
National report — Drug companies have begun responding to infectious diseases, which are growing not only in prevalence, but also, in some
cases, in virulence and drug resistance, an expert tells Dermatology Times.
"For a while, to a degree, people had an idea that bacterial infections, to a large extent, were conquered," says Robert S.
Kirsner, M.D., Ph.D., associate professor in the University of Miami's department of dermatology and cutaneous surgery. Accordingly,
he says researchers focused on other infectious processes such as those due to viruses, which were considered the biggest
public health scourge through the 1980s and 1990s.
"In fact," he says, "advances in treatments for common bacterial and skin infections have lagged behind. There were really
very few new antibiotics developed in the 1990s for skin infections, especially drug-resistant infections, while the resistance
has increased dramatically. There's been a significant rise in methicillin-resistant Staphylococcus aureus (MRSA), and more recently a different subtype of MRSA," namely, community-acquired MRSA (CA-MRSA).
Resistant organisms
Other resistant organisms causing concern include both S. aureus and enterococcus that are resistant to vancomycin, Dr. Kirsner adds.
"At our hospital and in many others," he says, "three-fourths of the patients who have S. aureus grown from their skin or wounds have MRSA. But an emerging number of patients in the community have CA-MRSA. CA-MRSA differs
because of different antibiotic sensitivities and mechanisms of action." Furthermore, he says that because CA-MRSA can produce
certain toxins that mimic symptoms of other conditions such as pyoderma gangrenosum, appropriate diagnosis is key.
"Fortunately," he adds, "the pharmaceutical companies have responded to some extent in recent years, developing a host
of new antibiotics treatments."
New antibiotics
New antibiotic treatments include Zyvox (linezolid, Pfizer) and, during the past year, drugs such as tigecycline, an intravenous
minocycline derivative that Dr. Kirsner says has proven comparable to vancomycin and aztreonam.
Other new IV antibiotics include ertapenem and dalbavancin, the latter of which he says offers "amazingly convenient dosing."
Two different weekly doses — the first week 1 g, then 500 mg in the second — performed as well as two weeks of twice-daily
linezolid for MRSA skin infections (Jauregui LE et al. Clin Infect Dis. 2005 Nov 15;41(10):1407-1415. Epub. 2005 Oct 6.), Dr. Kirsner says.
Bacterial infections rank among the most common infections dermatologists see, as well as the most potentially dangerous,
he adds.
Global society
In addition to the increasing prevalence and virulence of infectious disease, he says the global nature of modern society
is delivering a greater number of unusual infections to U.S. dermatologists' doorsteps.
"One of them is leishmaniasis among returning soldiers," Dr. Kirsner says. "It's important that clinicians add this to their
differential diagnosis because we are seeing and may continue to see these conditions more frequently."
Onychomycosis
Regarding onychomycosis, he says prevalence figures continue to rise because the U.S. population continues to change. "As
we have an older population — patients with increasing incidence of diabetes and vascular disease — there's an increasing
incidence of onychomycosis," he says.
Localized skin infections
For localized skin infections, Dr. Kirsner reports that development efforts continue on new antibiotic delivery systems. Examples
include the use of artificial skin to deliver antibiotics, which is the subject of ongoing research worldwide. One such system,
from Japan, is an experimental living-skin equivalent that contains both epidermis and dermis and has been impregnated with
tetracycline and chloramphenicol that is released into wounds over several hours, he says.
At the same time, he says pharmaceutical companies are incorporating very broad-spectrum agents into delivery systems such
as silver products in various dressings or matrices that deliver an antimicrobial effect within the context of advanced wound
care.
Technical advances
Other technical advances for treating infectious diseases include the VisualDx system (Logical Images), reports Art Papier,
M.D., an associate professor of dermatology and medical informatics at the University of Rochester College of Medicine and
chief scientific officer of Logical Images.
"The idea is that not only dermatologists, but all physicians, including emergency physicians, should have access to the best
information at the time the patient is evaluated," he says.
Because dermatologists aren't always available in emergency rooms, VisualDx incorporates a database containing thousands
of relationships critical in making rare as well as common diagnoses, Dr. Papier says.
"Healthcare information technology appears to be an invaluable tool for the dermatologist in these times of emerging and reemerging
infectious disease," he says.
We subscribe to the HONcode principles of the Health On the Net Foundation