A survey of over 1000 bacterial isolates from Maltese patients with urinary tract infection was performed in order to investigate resistance patterns to commonly used oral antibiotics. Resistance was detected in high frequency, particularly for ampicillin, trimethoprim and sulphonamides, in samples originating from both community and hospital. A population comparison to a similar survey conducted in the UK showed local resistance rates to be twice as high.peer-reviewe

Borg, Michael Angelo

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Malte se Medical Journ al 25 Volume V Issue 2 1993 ANTIBIOTIC SENSITIVITIES OF URINARY TRACT PATHOGENES IN MALTESE PATIENTS M. A. BORG ABSTRACT A survey of over 1000 bacterial isolates from Maltese patients with urinary tract infection was performed in order to investigate resistance patterns to com­monly used oral antibiotics. Resistance was detected in high frequency, particularly for ampicillin, trimethoprim and sulphonamides, in samples origi­nating from both community and hospital. A popula­tion comparison to a similar survey conducted in the UK showed local resistance rates to be twice as high. INTRODUCTION The knowledge of current resistance patterns is vital to the successful treatment of urinary tract infections (UTI). Most community cases are treated without concurrent laboratory investigation. Even when a mid-stream urine specimen is sent to the laboratory, a result will not be available before a minimum of 48 hours. Local factors and prescribing patterns greatly int1uence the incidence of resistance and therefore regular monitoring of such trends is essential to formul ate proper antibiotic pre­scribing guide-lines. MATERIALS & METHODS The survey studied 1052 consecutive bacterial isolates from urine samples submitted to the Bacteriology Labo­ratory, SI. Luke 's Hospital over a three month period between February and A pri I 1991. Specimens were designated as "Community" or "Hospital" depending upon their origin ; the former comprised specimens sub­mitted from out-patient departments and health centres. Primary plating was carried out within 30 minutes of submission on Cystine Lactose Electrolyte Deficient (CLED) and MacConkey media. Isolates showing not more than two colonial morphologies at concentrations of > I 05 bacteria/ml of urine were interpreted as indicat­ing significant bacteruria. Bacterial identification up to species level was carried out according to morphological and biochemical characteristics. Antibiotic susceptibility was performed by means of a non-comparative disc diffu sion technique using IsoSensititest medium (Oxoid) . The antibiotics chosen .' were first line oral agents in most common local use and tested at the following concentrations: ampicillin (25ug) , trimethoprim (1.25ug), nalidixic acid (30ug), cefuroxime (30ug), sulphonamide (I OOug), nitrofurantoin (300ug) and amoxycillin/c\avulanic acid (30ug). Statistical analysis of probability limits was calculated from the standard error of difference between the two sets of percentages obtained. RESULTS Species isolated As was to be expected the maj ority of isol ates were obtained from ages of 60 years or more with a female predominance of 61.5%. Overall , the most common species isolated was Escherichia coli (35.4%) followed by Pseudomonas aeruginosa (9.2%), Proteus vulgaris (8 .3%), Klebsiella (7.4%), Enterobacter (7.1 %) and Enterococci (6 .9%). Figure I depicts the frequency distribution of isolates according to origin. Escherichia coli is the predominant organism particularly in community specimens; other members of the Enterobacteriacae are more frequently isolated from ho spitali sed patients particularly Pseudomonas, Klehsiella and Proteus. The resistance patterns in hospital and community strains investigated are seen in Table I. In the majority of isolates, particularly those originating from hospi talised patients, resistance levels of over 20% are evident for most antibiotics tested. In order to assess the severity or otherwise of the antibi­otic resistance problem in the local setting, data obtained for E. coli were compared with equivalent results ob­tained from a similar study performed at University College Hospital, London, England (I). This organism MICHAEL A. B ORG , MD, MSc (LOND) DEPT. OF P ATHOLOGY ST. L UKE'S HOS PITAL, GwARDAMANGA ___ _ ---- --- - - --- - ------- - - - -Maltese Medical Journal 26 Volume V Issue 2 1993 FIGURE 1 Species isolated by origin and frequency E. cou JIII. --------IIIII!I------Pseudomonas ,--. Proteus J••••••I_~--___. Klebsiella -1l••• Enterobacter --1l••• Serratia Staph. aureus Citrobacter Other G - rods COMMUNITY (n=245) Other G + cocci ~_ _ HOSPITAL (n=807) Yeast spp. o 5 10 15 20 25 30 35 40 45 50 55 60 TABLE I The overall proportion ofbacterial isolates ofcommunity (245 isolates) and hospital (807 isolates) origin showing resistance to specific antibiotics. l ANTIBIO~ __1_ COMMUNTTY HOSP~ I Ampicillin 44.1% 51.0% N.S. I Trimethoprim 39.6% 49.0% p<O.Ol Nalidixic Acid 20.8% 23.8% N.S. Cefuroxime 9.0% 19.5% p<O.OOOl Sulphonamides 69.8% 67.9% N.S. Nitrofurantoin 19.6% 30.4% p<O.OOI Amoxycillin + Clavulanic Acid 16.7% 2l.5%  N.S· _ I TABLE 11 Comparison ofresistance incidence in community E.coli strainsfrom Malta (127 isolates) and London (807 isolates). ANTIBIOTIC MALTA LONDON ~ --l Ampicillin 47.2% 24.0% p<O.OOOI Trimethoprim 33.1% 17.9% p<O.OOI Nalidixic Acid 11.0% 11.4% N.S. Cefuroxime 7.1%  * Sulphonamides 69.3% 29.5% p<O.OOOl Nitrofurantoin 3.9% 16.2% p<O.OOOII Amoxycillin + Clavulanic Acid 3.1% * _J _ _ J Maltese Medical Journal 27 Volume V Issue 2 1993 TABLE III Comparison of resistance incidence in hospital E.coli strains Malta (234 isolates) and London (4238 isolates). ANTIBIOTIC 	 I MALTA Ampicilliin 56.0% Trimethoprim 44.4% Nalidixic Acid 14.5% Cefuroxime 7.7% Sulphonamides 71.4% Nitrofurantoin 15.0% Amoxycillin + Clavulanic Acid 4.3% * no data available from London study. was chosen because it is by far the commonest pathogen in urinary tract infection and eliminates bias due to other organisms such as Pseudomonas, Klebsiella and Enterobacter that are inherently resistant to many first­line antibiotics. Both hospital and community strains isolated locally show markedly increased resistance when compared with those isolated in London, particularly with respect to trimethoprim, nalidixic acid, nitrofurantoin and sul­phonamides (Tables II & Ill). DISCUSSION The results show no significant difference in resistance levels between hospital and community strains for ampicillin, nalidixic acid, sulphonamides and amoxycillin/clavulanic acid. Highly significant differ­ences (p<O.OO 1) are only apparent for cefuroxime (avail­able in an oral form only recently) and nitrofurantoin (rapidly falling out of favour in general practice). This state of affairs strongly differs from most European countries where resistance in community strains is often much lower than equivalent hospital isolates (2). Such a situation would indicate a wide-spread use (and possibly mis-use) of antibiotics in the community. References 1. 	 Gruneberg RN. Changes in the antibiotic sensi­tivities of urinary pathogens, 1971-1989. J. of Antimicrobial Chemotherapy 1990; 26, Suppl F:3-11. 2. 	 Lionsquay G, Delaitre E, Pin P, Bourlioux P et al. LONDON 43.1% p<O.OOI 23.9% p<O.OOOI 2.1% p<O.OOOI * 40.9% p<O.OOOI 5.8% p<0.005 * The role of long-established drugs, such as ampicillin and co-trimoxazole, in the treatment of urinary tract infections needs to be evaluated. Antimicrobials that have in recent years fallen out of favour, particularly nalidixic acid and nitrofurantoin, remain useful alterna­tives particularly for uncomplicated UTI's out of hospi­tal. The overall resistance patterns are alarmingly higher than those found in the London study (1), sometimes with up to two-fold increase for practically all antibiotics compared. This is a very discouraging situation that can only be remedied by judicious use ofantibacterial agents in both the community and hospital setting. In this first comprehensive study of antibiotic resistance in Malta, the relative sensitivities of urinary isolates to a series of antimicrobials have been investigated. In the light of the findings it is clear that antibiotic treatment strategies, both at hospital and general practice levels, need to be reviewed and appropriate action taken if the high degree of resistance elucidated is to decrease appre­ciably in the near future. Incidence of isolation and antibiotic resistance of E. coli responsible for urinary infections outside hospitals, in specialised hospitals and in general hospitals. Path BioI Paris 1984; 32(5): 389-395. The copyright of this article belongs to the Editorial Board of the Malta Medical Journal. The Malta Medical Journal’s rights in respect of this work are as defined by the Copyright Act (Chapter 415) of the Laws of Malta or as modified by any successive legislation. Users may access this full-text article and can make use of the information contained in accordance with the Copyright Act provided that the author must be properly acknowledged.  Further distribution or reproduction in any format is prohibited without the prior permission of the copyright holder. This article has been reproduced with the authorization of the editor of the Malta Medical Journal (Ref. No 000001)  

Antibiotic sensitivities of urinary tract pathogenes in Maltese patients

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Antibiotic sensitivities of urinary tract pathogenes in Maltese patients

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