Antibiotics and resistance: the two-faced Janus of antibiotic therapy
Abstract
Stefania Stefani, Professor of Microbiology (Department of Biomedical and Biotechnological Sciences, University of Catania), introduced the the subject of antibiotic resistance with a concise report identifying the causes and mechanisms behind this worrying phenomenon.
Among the causes of Multi-Drug Resistance (MDR) are identified: the use of prolonged empirical therapies, the administration of sub-optimal dosages and the first-line use of molecules with a high capacity to generate resistance.
Moreover, antibiotics have been used and abused, not only for human use, but also in animal and livestock husbandry, food production and the environment - so much so that microbial strains have acquired multiple resistances, i.e. towards many (if not all) antibiotic families.
This phenomenon, which often arises within hospitals, is increasing exponentially in many countries around the world, affecting our ability to treat common infections, such as pneumonia, tuberculosis, bacteremia, gonorrhoea, which are becoming almost impossible to treat.
The phenomenon of so-called "superbugs" then takes on some specificities and problematic aspects in the case of diseases affecting the eye and this special paper of 'l'Oculista italiano' is dedicated to this topic.
Problems of antibiotic therapy in ophthalmologyÂ
Abstract
Giuseppe Grandi, Director of the Complex Structure of Clinical Pathology of ASL1 in Turin and specialist in Microbiology, Clinical Pathology, offers an in-depth analysis of the problems of antibiotic therapy in ophthalmology.
The ocular surface, as is well known, is not sterile, but characterised by the presence of a microbiomewhich plays an important role in the defence against colonisation by other pathogens and creates a balance within it such that opportunistic germs do not emerge.
Today, the worrying phenomenon of antibiotic resistance calls for a targeted use of antibiotics that is based on a careful assessment of the characteristics of the bacterial flora that cause the various eye diseases. In mild forms (conjunctivitis), the bacteria primarily responsible are generally those belonging to the microbiome that, for some reason, take over and become pathogenic (primarily Staphylococci and Streptococci). In these cases, which tend to be self-limiting, one could also rule out any kind of treatment, but the use of broad-spectrum topical antibiotics is helpful in reducing their duration, allowing a more rapid recovery.
However, in the case of conjunctival infections in immunocompromised patients, patients with altered adnexa, patients with altered tear film, and patients with contact lenses in whom the lesions may evolve, it is advisable to perform a conjunctival smear before starting therapy, which is then examined and interpreted at a reference centre. This is the only way to avoid the indiscriminate use of the latest generation of antibiotics and use those specific to the isolated germ.
In the case of keratitis, therapy should be started immediately, but at the same time, the corneal lesion should always be sampled and analysed using molecular biology techniques and/or a classical technique. Upon identification of the germ and/or antibiogram, therapy should be carried out with the best possible antibiotic against the isolated germ.
Today, the greatest concerns come from the growing resistance of CoNS and the decreasing sensitivity of Staphylococcus aureus to the older aminoglycosides, but especially to fluoroquinolones. This means a progressive loss of important weapons against the germs most present in both conjunctivitis and keratitis, and also in the majority of serious ocular infections, since together with the problem of methicillin resistance, the problem of multiresistance is becoming increasingly evident. In contrast, the excellent performance of the netilmicin on methicillin-resistant Staphylococcus aureus (MRSA) and multi-resistant CoNS (MRSE) and even more so the maintenance over the last 20 years of the drug's efficacy on Staphylococci - Staphylococcus aureus and CoNS.
Netilmycin, a current and responsible choice
Abstract
Rita Mencucci, Adjunct Professor of Ophthalmology and Diseases of the Visual Apparatus (A.O.U. of Careggi - University of Florence) was invited to draft the conclusions of this paper dedicated to the correct use of antibiotic therapy in Ophthalmology in the face of increasing antibiotic resistance.
The main clinical indications for the use of antibiotics in ophthalmology are infections of the outer eye (mainly conjunctivitis e keratitis) and on the other the prophylaxis of post-surgical infections.
In the case of external infections, a detailed anamnesis and a thorough specialist examination make it possible in most cases to precisely define the cause and to institute appropriate therapy.
However, there is no general rule for choosing the most suitable antibiotic, but it is of great importance to take into account the saprophytic flora and consequently the local pattern of resistance.
Regarding post-surgical infections (endophthalmitis), Although they have a very low incidence today (0.04%-0.13), they remain the most feared and devastating complications in ophthalmology, so it is common practice among surgeons to use pre-, intra- and post-operative antibiotic prophylaxis.
From the careful examination of the microbiological considerations set out in this paper and the latest scientific evidence, the Netilmicin, after 20 years of use in ophthalmology, is confirmed as an optimal antibiotic, associated with a reduced incidence of resistance cases.
Dr. Carmelo Chines
Direttore responsabile
English 
Italian