High antimicrobial resistance among bacterial isolates of blood stream infections (BSI) in a Nigerian University Teaching Hospital

The antimicrobial resistance profile of 220 bacteria isolated from 1,006 episodes of blood stream infections (BSI) between January 2004 and December 2005 in a University Teaching Hospital, Southwestern Nigeria, were analyzed. Gram positive bacteria constituted 47.3% while Gram negative constituted 52.7%. The most common organisms were Staphylococcus aureus (37.3%), Klebsiella (30%), Pseudomonas (8.2%), Proteus (6.4%), Escherichia coli (5.5%) and coagulase negative staphylococci (4.6%). The cumulative resistance of all the bacteria isolates to ampicillin was 79%, gentamicin 51%, ceftazidime 11% and ciprofloxacin 6%. About 85% of the Gram positive bacteria were resistant to penicillinG, 79% to methicillin and 37% to erythromycin while 74% of the Gram negative bacteria were resistant to cotrimoxazole, 69% to tetracycline and 38% to chloramphenicol. Among the 7 antibiotics tested for each group, 7 patterns of antibiotic resistance were observed for each; 6 were multi-drug pattern with number of antibiotics ranging from 2 to 7. This study demonstrates high antimicrobial resistance among clinical bacterial isolates of BSI to commonly prescribed antibiotics most especially penicillinG, ampicillin, methicillin, cotrimoxazole, tetracycline and gentamicin. Based on the result of this study, it is suggested that the combination of ampicillin and gentamicin normally employed for empirical treatment of BSI in our hospital should be stopped.     

Antibiotic sensitivity pattern; experience at University Hospital, Riyadh, Saudi Arabia

Results of sensitivity testing were discussed based on examination of 5192 isolates of the various bacteria isolated from clinical specimens from King Khalid University Hospital in Riyadh, Saudi Arabia. Streptococcus pyogenes and Streptococcus pneumoniae were sensitive to penicillin and erythromycin. The sensitivity pattern of Staphylococcus aureus was also predictable as they were fairly sensitive to both methicillin (98%) and erythromycin (96%). Neisseria gonorrhoeae (27%) showed a high level of resistance to penicillin. The resistance of Haemophilus influenzae to ampicillin and chloramphenicol was low. Brucella species was sensitive to tetracycline and rifampicin; resistance to streptomycin and cotrimoxazole was minimal being 1% and 6% respectively. The resistance of E. coli, Klebsiella species and Proteus species to second and third generation cephalosporins and amikacin was fairly low ranging from 1.3% to 3%. The gentamicin resistance for these organisms was also within the acceptable range (3%-10%). Gentamicin and amikacin resistance for Pseudomonas aeruginosa was low (2-8%). Salmonella typhi was sensitive to ampicillin, cotrimoxazole, and chloramphenicol. Salmonella enteritidis, Shigella species, and enteropathogenic E. coli were highly resistant to various antibiotics. Campylobacter jejuni was sensitive to gentamicin but 6% of isolates were resistant to erythromycin. Ninety six percent of Gram-negative rods except P. aeruginosa isolated from urine of patients having urinary tract infections were sensitive to amoxycillin-clavulanic acid. In addition, P. aeruginosa showed fairly low resistance to norfloxacin which is given orally to treat cystitis caused by this organism.     

Conditional probability analysis of multidrug resistance in Gram-negative bacilli isolated from tertiary medical institutions in South Korea during 1999–2009

Multidrug resistance of Gram-negative bacilli is a major problem globally. However, little is known about the combined probability of resistance to various antibiotics. In this study, minimum inhibitory concentrations of widely used antibiotics were determined using clinical isolates of Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii, randomly chosen from strain collections created during 1999–2009 in tertiary medical institutions in Seoul, South Korea. To analyze combined efficacy of antibiotics against a subgroup of isolates, conditional probabilities were determined based on arbitrary, non-independent patterns of antimicrobial susceptibility and resistance. Multidrug resistance, defined as resistance to three or more classes of antibiotics, was observed in the following order: A. baumannii (96%), P. aeruginosa (65%), E. coli (52%), and K. pneumoniae (7%). A. baumannii strains resistant to gentamicin were found to be resistant to a number of antibiotics, except for colistin and polymyxin B. Resistance to gentamicin following exposure to this antibiotic was highly likely to lead to multidrug resistance in all four microbes. This study shows a causal relationship between gentamicin resistance and the prevalence of multidrug resistance in clinical isolates of Gramnegative bacilli in South Korea during 1999–2009 and suggests the importance of prudent use of gentamicin in hospitals.     

Characteristics of clinical<Emphasis Type="Italic">Acinetobacter</Emphasis> spp. strains

Resistance to 13 antimicrobial agents, resistance to the bactericidal activity of human serum, hydrophobic properties, lipolytic activity and production of histamine were determined in a total of 50 clinicalAcinetobacter spp. strains (A. baumannii, A. lwoffii, A. calcoaceticus, A. haemolyticus). None of the tested isolates showed resistance to meropenem and none ofA. lwoffii, A. calcoaceticus andA. haemolyticus strains were resistant to amikacin. Forty-six strains (92 %) manifested resistance to ampicillin, 90 % to cefuroxime, 68 % to ciprofloxacin, 58 % to piperacillin, gentamicin and cotrimaxazole, 50 % to cefotaxime, 44 % to amikacin, 42 % to ceftazidime, 38 % to piperacillin/tazobactam, 24 % to netilmicin and 16 % to ampicillin/sulbactam. In particular,A. baumannii andA. calcoaceticus strains showed considerable antibiotic resistance. Thirty-one isolates (62 %) showed serum resistance; intermediate sensitivity was found in 19 isolates (38 %). The majority of the strains (72 %) demonstrated a strongly hydrophobic character; 16 % of isolates exhibited moderate hydrophobic properties. All strains showed lipolytic activity; production of histamine was detected in 14 of 43 strains examined.     

Antibiotic resistance and virulence traits in clinical and environmental Enterococcus faecalis and Enterococcus faecium isolates

This study compared virulence and antibiotic resistance traits in clinical and environmental Enterococcus faecalis and Enterococcus faecium isolates. E. faecalis isolates harboured a broader spectrum of virulence determinants compared to E. faecium isolates. The virulence traits Cyl-A, Cyl-B, Cyl-M, gel-E, esp and acm were tested and environmental isolates predominantly harboured gel-E (80% of E. faecalis and 31.9% of E. faecium) whereas esp was more prevalent in clinical isolates (67.8% of E. faecalis and 70.4% of E. faecium). E. faecalis and E. faecium isolated from water had different antibiotic resistance patterns compared to those isolated from clinical samples. Linezolid resistance was not observed in any isolates tested and vancomycin resistance was observed only in clinical isolates. Resistance to other antibiotics (tetracycline, gentamicin, ciprofloxacin and ampicillin) was detected in both clinical and water isolates. Clinical isolates were more resistant to all the antibiotics tested compared to water isolates. Multi-drug resistance was more prevalent in clinical isolates (71.2% of E. faecalis and 70.3% of E. faecium) compared to water isolates (only 5.7% E. faecium). tet L and tet M genes were predominantly identified in tetracycline-resistant isolates. All water and clinical isolates resistant to ciprofloxacin and ampicillin contained mutations in the gyrA, parC and pbp5 genes. A significant correlation was found between the presence of virulence determinants and antibiotic resistance in all the isolates tested in this study (p<0.05). The presence of antibiotic resistant enterococci, together with associated virulence traits, in surface recreational water could be a public health risk.     

A novel large plasmid carrying multiple beta-lactam resistance genes isolated from a Klebsiella pneumoniae strain

Klebsiella pneumoniae clinical isolates were selected according to the results of antibiotic susceptibility tests. Most of them were resistant to multiple antibiotics, including ampicillin, ceftazidime, cefotaxime and aminoglycosides. Large plasmids were observed in these Kl. pneumoniae strains by pulsed-field gel electrophoresis with S1 nuclease digestion. The Kl. pneumoniae strains investigated produced one to two extrachromosomal bands with a mobility corresponding to 97 approximately 145 kbp linear DNA molecules. A 100 kbp plasmid, designated pK1, was observed in the multiply resistant strain K250. pK1 had sequences homologous to both the TEM-1 and the aphD probe which were associated with beta-lactam and aminoglycoside resistance. pK1 was transformed into Escherichia coli strain DH5alpha and was found to confer resistance to ampicillin, ceftazidime, cefotaxime and kanamycin. A 8 kbp BamHI DNA fragment of pK1 that carried the ampicillin resistance gene (minimum inhibitory concentration > 1000 microgram ml-1) was cloned into the BamHI site of pACYC184. Sequence determination showed that this cloned fragment carried a TEM-1 gene. These findings suggest that pK1 is novel in that it appears to carry genes for resistance to ampicillin, cefotaxime and ceftazidime, as well as kanamycin.     

Effect of subtherapeutic administration of antibiotics on the prevalence of antibiotic-resistant Escherichia coli bacteria in feedlot cattle

Antibiotic-resistant Escherichia coli in 300 feedlot steers receiving subtherapeutic levels of antibiotics was investigated through the collection of 3,300 fecal samples over a 314-day period. Antibiotics were selected based on the commonality of use in the industry and included chlortetracycline plus sulfamethazine (TET-SUL), chlortetracycline (TET), virginiamycin, monensin, tylosin, or no antibiotic supplementation (control). Steers were initially fed a barley silage-based diet, followed by transition to a barley grain-based diet. Despite not being administered antibiotics prior to arrival at the feedlot, the prevalences of steers shedding TET- and ampicillin (AMP)-resistant E. coli were >40 and <30%, respectively. Inclusion of TET-SUL in the diet increased the prevalence of steers shedding TET- and AMP-resistant E. coli and the percentage of TET- and AMP-resistant E. coli in the total generic E. coli population. Irrespective of treatment, the prevalence of steers shedding TET-resistant E. coli was higher in animals fed grain-based compared to silage-based diets. All steers shed TET-resistant E. coli at least once during the experiment. A total of 7,184 isolates were analyzed for MIC of antibiotics. Across antibiotic treatments, 1,009 (13.9%), 7 (0.1%), and 3,413 (47.1%) E. coli isolates were resistant to AMP, gentamicin, or TET, respectively. In addition, 131 (1.8%) and 143 (2.0%) isolates exhibited potential resistance to extended-spectrum beta-lactamases, as indicated by either ceftazidime or cefpodoxime resistance. No isolates were resistant to ciprofloxacin. The findings of the present study indicated that subtherapeutic administration of tetracycline in combination with sulfamethazine increased the prevalence of tetracycline- and AMP-resistant E. coli in cattle. However, resistance to antibiotics may be related to additional environmental factors such as diet.     

Susceptibility of sixty-five non-oral clinical isolates of the Streptococcus milleri group to seven antimicrobial agents.

Antimicrobial susceptibilities of sixty-five non-oral Streptococcus milleri group clinical isolates to penicillin, gentamicin, lincomycin, ampicillin, chloramphenicol, tetracycline and erythromycin were determined by an agar dilution method. All strains were penicillin-sensitive (MIC < or = 0.031 microgram/ml) and the majority (64/65) were susceptible to erythromycin (MIC < or = 0.125 microgram/ml). Low-level resistance to gentamicin was observed, and the majority of strains possessed an MIC of 8 micrograms/ml. Lincomycin and ampicillin at 0.5 microgram/ml inhibited 52/65 and 61/65 strains, respectively. Of the isolates 92% were inhibited by chloramphenicol at < or = 2 micrograms/ml. Twenty-two S. milleri group strains (of which thirteen were vaginal isolates) were resistant to tetracycline (MIC > or = 8 micrograms/ml).     

Occurrence and susceptibility to antibiotics of carbapenem-resistant Pseudomonas aeruginosa strains between 1998 and 2009

P. aeruginosa rods are dangerous pathogens mainly responsible for nosocomial infections of different localization. Resistance to carbapenems, observed among them, is a serious threat due to ability to be transmitted between bacterial species. The aim of our study was to retrospectively evaluate the frequency of isolation and susceptibility to antibiotics of imipenem- and meropenem-resistant P. aeruginosa strains isolated between 1998 and 2009 from patients of University Hospital No 1 of dr A. Jurasz in Bydgoszcz. Study shows increasing number of isolation that type of strains from 19 in 1998 to 144 in 2009. Among all isolated P. aeruginosa strains majority was obtained from patients of the Intensive Care Units, Rehabilitation and Surgery Clinics. Examined strains of P. aeruginosa rods were mainly isolated from urine (20.5%), bronchoalveolar lavage (17.7%) and wound swabs (14.5%) samples. The isolates demonstrated frequently resistance to carbenicillin (> or 66.7%), ticarcillin (> or = 72.7%) and cefotaxime (> or = 75.6%). The lowest rate of resistant strains was observed in case of ceftazidime (< or = 68.8%), aztreonam (< or = 47.4%) and colistin (< or = 1.7%) suggesting the highest activity of that antimicrobials against infections caused by examined strains.     

Susceptibility of Pseudomonas aeruginosa to Gentamicin Sulfate In Vitro: Lack of Correlation Between Disc Diffusion and Broth Dilution Sensitivity Data

Seventy-eight of 420 clinical isolates of Pseudomonas aeruginosa yielded zones of inhibition of less than 12 mm in diameter around 10-mug discs of gentamicin sulfate when tested by the standardized Bauer-Kirby disc diffusion method. Of 153 strains chosen from these isolates, one strain (0.65%) required 25 mug of gentamicin per ml for inhibition; the remainder (99.35%) were inhibited by 6 mug/ml or less of the antibiotic. It is recommended that those isolates of P. aeruginosa that yield zones of inhibition less than 12 mm in diameter be disc susceptibility-tested once more; those isolates that give zones of inhibition of less than 12 mm upon repeated examination should then be subjected to the broth dilution test before they are designated as sensitive or resistant to gentamicin.     

The structure and antibiotic sensitivity of the causative agents of community-acquired infectious diseases of bacterial origin in children]

Four hundred and forty pediatric patients at the age of 7 days to 15 years with various infections admitted to the Hospital within a month were examined. The biological material was inoculated to blood agar on the first days of the patient admittance to the Hospital and after the growth the organisms were isolated and identified. Antibiotic susceptibility of the isolates was assayed with the disk diffusion method. 479 strains in all were tested. The most frequent cases requiring hospitalization and antibiotic therapy were those of respiratory tract infections (54.09 per cent), urinary tract infections (26.36 per cent), cutaneous and subcutaneous fat diseases, gastrointestinal diseases and others (about 25 per cent of the cases in all). The main pathogens were Streptococcus viridans, S.aureus and S.epidermidis, as well as Enterobacteriaceae (chiefly E.coli) whose frequencies were practically equal (in 25-35 per cent of the cases). The Pneumococcus isolates amounted to 6.3 per cent. Nonfermenting bacteria (Pseudomonas aeruginosa and Acinetobacter) and some representatives of Enterobacteriaceae (Citrobacter, Serratia, Morganella) were isolated from 7 per cent of the patients. The frequency of Klebsiella and Enterobacter was about 11 per cent. The main pathogens were tested for their susceptibility to amoxycillin/clavulanic acid, ampicillin, oxacillin and gentamicin. The least active antibiotic was ampicillin. 88.8 per cent of the E.coli isolates and 100 per cent of the Klebsiella, P.mirabilis, Morganella, Citrobacter, Enterobacter and Serratia isolates were resistant to it. 53.2 per cent of the Streptococcus isolates including 64.5 per cent of the Pneumococcus isolates were as well resistant to ampicillin. 59.5 per cent of the Streptococcus isolates (mainly S.viridans and Enterococcus) was susceptible to oxacillin, 22.2 per cent of them being moderately susceptible. 62.5 per cent of the Pneumococcus isolates and 78.1 per cent of the Staphylococcus isolates were also susceptible to oxacillin. The highest susceptibility of the isolates was that to amoxycillin/clavulanic acid, i.e. 90.1 per cent of the strains, 79.9 per cent of them being highly susceptible. All the isolates of Citrobacter, Serratia and Morganella and some isolates of P.aeruginosa, Acinetobacter, Enterobacter, Klebsiella and E.coli were resistant to amoxycillin/clavulanic acid. As for the latter 5 organisms their susceptibility to amoxycillin/clavulanic acid was comparable with that to gentamicin. The susceptibility of the Streptococcus and Staphylococcus isolates to amoxycillin/clavulanic acid was significantly much higher than that to oxacillin, gentamicin and ampicillin: 93 per cent of the Streptococcus isolates (62.7 per cent of the Pneumococcus isolates) and 90.7 per cent of the Staphylococcus isolates.     

An inexpensive infrared growth sensor array for detection of bacterial antibiotic susceptibility

Abstract An inexpensive infrared sensor was constructed and used for the rapid testing of bacterial antibiotic susceptibility by detection of changes in absorbance at 950 nm. By comparing cultures of clinical isolates together with control strains ( Escherichia coli NCTC 10418, Staphylococcus aureus NCTC 6571 or Pseudomonas aeruginosa NCTC 10662) after addition of an antibiotic, results on susceptibility were obtained within 3–5 h from the original plate culture. Representative strains of E. coli, P. aeruginosa , and S. aureus were tested successfully against ampicillin, penicillin, gentamicin or ciprofloxacin.     

The patterns and transmissibility of antibiotic resistance among clinical strains of Pseudomonas aeruginosa.

Four hundred and ninety-eight predominantly pyocin-type 10 clinical strains of Pseudomonas aeruginosa were analyzed for resistance to carbenicillin, cefoperazone, cefotaxime, ceftazidime, gentamicin, amikacin and netilmicin. Based on NCCLS-recommended MIC breakpoints, 245 strains were found to be resistant, of which 41.6% were resistant to carbenicillin, 38% to gentamicin, 37.8% to netilmicin, 26.3% to cefoperazone, 17.9% to cefotaxime, 0.6% to amikacin and none to ceftazidime. Quadruple resistance to carbenicillin, cefoperazone, gentamicin and netilmicin was the most frequent pattern observed. Resistance to older antibiotics (kanamycin, streptomycin and tetracycline) and to mercuric chloride were also common. Conjugation experiments suggested that self-transmissible and non-transmissible plasmids occurred in at least 66 strains.     

Detection of Salmonella spp. in retail raw food samples from Vietnam and characterization of their antibiotic resistance

A study was conducted to examine the levels of Salmonella spp. contamination in raw food samples, including chicken, beef, pork, and shellfish, from Vietnam and to determine their antibiotic resistance characteristics. A total of 180 samples were collected and examined for the presence of Salmonella spp., yielding 91 Salmonella isolates. Sixty-one percent of meat and 18% of shellfish samples were contaminated with Salmonella spp. Susceptibility of all isolates to a variety of antimicrobial agents was tested, and resistance to tetracycline, ampicillin/amoxicillin, nalidixic acid, sulfafurazole, and streptomycin was found in 40.7%, 22.0%, 18.7%, 16.5%, and 14.3% of the isolates, respectively. Resistance to enrofloxacin, trimethoprim, chloramphenicol, kanamycin, and gentamicin was also detected (8.8 to 2.2%). About half (50.5%) of the isolates were resistant to at least one antibiotic, and multiresistant Salmonella isolates, resistant to at least three different classes of antibiotics, were isolated from all food types. One isolate from chicken (serovar Albany) contained a variant of the Salmonella genomic island 1 antibiotic resistance gene cluster. The results show that antibiotic resistance in Salmonella spp. in raw food samples from Vietnam is significant.     

Antimicrobial susceptibilities of Campylobacter sp strains isolated from humans in 2005 to 2006 in Bielsko-Biala Region, Poland

Campylobacter jejuni and Campylobacter coli are frequent causes of bacterial gastroeneritis in humans worldwide. Campylobacteriois is usually a self-limiting disease and therapy with antibiotics is required in severe clinical infections. The objective [corrected] of this study was to determine the antibiotic resistance of C. jejuni and C. coli isolated from humans with diarrhea during 2005-2006 in Bielsko-Biala region in Poland. The MICs of ciprofloxacin, tetracycline, erythromycin, gentamicin and ampicillin were determined by the E-test method. It was observed that 23 % and 6% C. jejuni isolates were resistant to two and three antibiotics, respectively. All isolates of Campylobacter sp. were sensitive to erythromycin and gentamicin. From the 69 C. jejuni strains 58% were resistant to ciprofloxacin, 23% to tetracycline and 17% to ampicillin. From the 8 C. coli strains all were resistant to ciprofloxacin, 62,5% to ampicillin and 12,5% to tetracycline.     

Macrolides decrease the minimal inhibitory concentrations of anti-pseudomonal agents against Pseudomonas aeruginosa from cystic fibrosis patients in biofilm

ABSTRACT: BACKGROUND: Biofilm production is an important mechanism for bacterial survival and its association with antimicrobial resistance represents a challenge for the patient treatment. In this study we evaluated the in vitro action of macrolides in combination with anti-pseudomonal agents on biofilm-grown Pseudomonas aeruginosa recovered from cystic fibrosis (CF) patient. RESULTS: A total of 64 isolates were analysed. The (BIC) results were consistently higher than those minimal inhibitory concentration (MIC) for most anti-pseudomonal agents tested (ceftazidime: P = 0.001, ciprofloxacin: P = 0.234, tobramycin: P = 0.001, imipenem: P < 0.001, meropenem: P = 0.005). When macrolides were associated with the anti-pseudomonal agents, the BIC values were reduced significantly for ceftazidime (P < 0.001) and tobramycin (P < 0.001), regardless the concentration of macrolides. Strong (IQ) was observed when azithromycin at 8 mg/L was associated with all anti-pseudomonal agents tested in biofilm conditions. CONCLUSIONS: P. aeruginosa from CF patients within biofilms are highly resistant to antibiotics but macrolides proved to augment the in vitro activity of anti-pseudomonal agents.     

Changes in the rates of antimicrobial resistance among clinical isolates of Pseudomonas aeruginosa between 2002 and 2004 in a tertiary-care teaching hospital in Turkey

Pseudomonas aeruginosa is an important opportunistic pathogen usually resistant to most antimicrobials. We present changes in the resistance pattern of P. aeruginosa to amikacin (AK) and ciprofloxacin (CIP) between January 2002 and June 2004. The physicians of each unit were given information on antibiotic resistance rates of P. aeruginosa isolated from ward patients at regular intervals. The antibiotic resistance of 161 P. aeruginosa isolates isolated from intensive care units (ICUs) and non-ICUs were tested by disk diffusion method, and the results were interpreted according to the guidelines of National Committee for Clinical Laboratory Standards. Thirty-five percent of all the P. aeruginosa isolates were resistant to AK in 2002, 18% in 2003, and 20% in 2004. The CIP resistance rates were 4% in 2002, 26% in 2003, and 20% in 2004. In that period, resistance to AK decreased, whereas resistance to CIP increased. The usage rate of AK in 2002 was 32%, which fell to 26% in 2003 (p < 0.05). This rate increased to 27% in 2004 (p < 0.05). The usage rate of CIP was very low in 2002 (3%). Subsequently, it increased to 8% in 2003 and 2004 (p < 0.05). The changes in resistance rates may have been due to alteration in drug usage policy in our hospital. It is important to provide physicians with information on antibiotic resistance rates at regular intervals to guide therapy for critical P. aeruginosa infections.     

Prevalence and genotypic relatedness of carbapenem resistance among multidrug-resistant P. aeruginosa in tertiary hospitals across Thailand

ABSTRACT: BACKGROUND: Increased infection caused by multidrug resistant (MDR) Pseudomonas aeruginosa has raised awareness of the resistance situation worldwide. Carbapenem resistance among MDR (CR-MDR) P. aeruginosa has become a serious life-threatening problem due to the limited therapeutic options. Therefore, the objectives of this study were to determine the prevalence, the antibiotic susceptibility patterns and the relatedness of CR-MDR P. aeruginosa in tertiary hospitals across Thailand. METHODS: MDR P. aeruginosa from eight tertiary hospitals across Thailand were collected from 2007--2009. Susceptibility of P. aeruginosa clinical isolates was determined according to the Clinical and Laboratory Standards Institute guideline. Selected CR-MDR P. aeruginosa isolates were genetically analyzed by pulsed-field gel electrophoresis. RESULTS: About 261 clinical isolates were identified as MDR P. aeruginosa and approximately 71.65% were found to be CR-MDR P. aeruginosa. The result showed that the meropenem resistance rate was the highest reaching over 50% in every hospitals. Additionally, the type of hospitals was a major factor affecting the resistance rate, as demonstrated by significantly higher CR-MDR rates among university and regional hospitals. The fingerprinting map identified 107 clones with at least 95% similarity. Only 4 clones were detected in more than one hospital. CONCLUSIONS: Although the antibiotic resistance rate was high, the spreading of CR-MDR was found locally. Specific strains of CR-MDR did not commonly spread from one hospital to another. Importantly, clonal dissemination ratio indicated limited intra-hospital transmission in Thailand.     

Contribution of Pseudomonas Aeruginosa strains to infections in patients of specialistic outpatients clinics of the SP ZOZ in Nidzica

The aim of this study was to examine a frequency of isolation and analysis of drug susceptibility o P. aeruginosa strains cultured from clinical specimens obtained from patients treated in specialistic outpatient clinics of the Samodzielny Publiczny Zespó? Opieki Zdrowotnej (SP ZOZ) in Nidzica durin 40 months (01. 09. 2000 - 31. 12. 2003). Ninety six P. aeruginosa strains were cultured out of 829 clinical samples collected from ambulatory patients and processed in the Bacteriological Laboratory of SP ZOZ in Nidzica during over three years. P. aeruginosa strains were isolated from 11.6% of examined specimens. The greatest number of strains (49.0%) were cultured from urine samples obtained from children. Identification of strains was performed using biochemical tests (Becton Dickinson, Emapol, bio-Merieux). Susceptibility of strains to antimicrobial agents was determined with disc diffusion method according to NCCLS recommendations. Special tests were applied to detect extended-spectrum beta-lactamases (ESBL). The most active in vitro against isolated P. aeruginosa strains was a carbapenem - imipenem. All strains were susceptible to this antibiotic. Ciprofloxacin (94.8% of susceptible strains), ceftazidime (89.6%), gentamicin (86.5%), piperacillin (84.4%) and aztreonam (76.0%) were active against the majority of P. aeruginosa strains isolated from ambulatory patients. Six strains (6.25% of all strains) producing extended--spectrum beta--lactamases (ESBL) were detected. It is alarming, that the majority of P. aeruginosa strains from outpatients were cultured out of pediatric samples (61.5%). Because of an increase in resistance and appearance of new mechanisms of resistance to antibiotics/chemotherapeutics in P. aeruginosa strains, it is necessary to monitor a drug susceptibility of these strains causing infections in ambulatory patients.     

Antibiotic susceptibility of Listeria monocytogenes strains isolated in the Primor'e region]

Antibiotic susceptibility of the Listeria monocytogenes isolates from biotic and abiotic objects of the environment in the Primor'e region was estimated. 100% of the isolates proved to be susceptible to benzylpenicillin, ampicillin, carbenicillin, gentamicin, doxycycline, tetracycline, vancomycin, cefazolin and rifampicin. 96, 92 and 84% of the isolates were susceptible to roxithromycin, clarithromycin and ofloxacin respectively. No significant differences were detected in the susceptibility of the strains isolated from different objects of the environment. 100% of the Listeria monocytogenes isolates was resistant to lomofloxacin and ceftazidime.