Antibiotic susceptibility and occurrence of ESBL in Pseudomonas aeruginosa strains isolated from different clinical specimens

The aim of this study was to evaluate the drug susceptibility of 132 P. aeruginosa strains isolated from patients hospitalized in SPSK University Hospital in Bialystok. The isolates were obtained from clinical specimens over an 11-month period in 2001 and 2002. All the strains were identified in automatic ATB system using API 20 NE strips, and their susceptibility to antibiotics was tested by standard disc-diffusion method and agar dilution method. The minimal inhibitory concentration (MIC) was determined for five antibiotics: piperacillin, amikacin, ceftazidime, imipenem and ciprofloxacin. The majority of strains were susceptible to ceftazidime (91.7%), piperacillin combined with tazobactam (85.6%), amikacin (80.3%), meropenem and imipenem (81.8%). Many of our strains were resistant to cefotaxime (73.5%), ticarcillin (53%) and ciprofloxacin (48.5%). Also, the trial was undertaken to detect strains producing extended-spectrum beta-lactamases (ESBL) and inducible beta-lactamases (IBL) among P. aeruginosa rods isolated from different specimens. ESBL-producing strains were detected with double disc test (DDST) and combination double disc (CD) test. Clavulanate was applied as the inhibitor of these beta-lactamases. Strains producing ESBL were not found. On the other hand, as many as 127 P. aeruginosa strains (96.2%) produced inducible beta-lactamases (IBL).     

Antibiotic susceptibility and occurrence of ESBL, IBL and MBL in Pseudomonas aeruginosa strains

The aim of this study was to evaluate the drug susceptibility of P. aeruginosa strains and to detect strains producing inducible beta-lactamases (IBL), extended-spectrum beta-lactamases (ESBL), and metallo-beta-lactamases (MBL). During 6 month (October 2005 - March 2006), 66 strains of P. aeruginosa strains were cultured from clinical specimens obtained from patients of two of hospitals in Siedlce and from patients of outpatient clinics. All the strains were identified in the automatic ATB (bio Mérieux). The susceptibility of bacteria to antibiotics was tested by standard disc diffusion method. The majority of strains were susceptible to meropenem (89.4%), piperacillin combined with tazobactam (84.8%), ciprofloxacin (84.8%) and piperacillin (83.3%). Many of our strains were resistant to carbenicillin (69.7%), mezlocillin (45.5%), gentamicin (42.4%) and netylmicin (30.3%). 6 strains (9.1%) were multidrug-resistant (MDR). Inducible beta-lactamases were detected with the use double disc method according to Sanders and Sanders. ESBL-producing strains were detected with double disc test (DDST) according to Jarlier et al. These strains were identified as ESBL-positive on the basis of the DDST were also determined using a double disc (DD) test according to Appleton. Production of metallo-beta-lactamases (MBL) was examined with the use of Etest MBL (AB Biodisk, Sweden) and the double disc test according to Arakava et al. Sixty-five IBL-producing strains (98.5% of all strains) and three strains (4.5%) with MBL activity were detected. Strains producing extended beta-lactamases (ESBL) were not found.     

Antibmicrobial susceptibility of Serratia marcescens isolated from hospitalized patients in 2003 - 2005

500 strains of Serratia marcescens isolated in 2003-2005 were examined for drug susceptibility. By using several phenotypic methods it was shown that 67.6% of these strains produced ESBLs. Strains ESBL(-) and ESBL(+) were compared, paying special attention to their susceptibility to various antibiotics. It was revealed that strains ESBL(+) were much more resistant to majority of the investigated drugs. The biggest differences were in the case of amikacin and gentamicin, sensitive about 50% of ESBL(-) and 10% of ESBL(+), ciprofloxacin, sensitive 42% of ESBL(-) and 6.3% of ESBL(+) and trimethoprim/ sulphametoxazole, sensitive 45.8% of ESBL(-) and 9.4% of ESBL(+). Strains ESBL(-) retained a high susceptibility to ceftazidime (68.9%) and cefepime (71%). All strains ESBL(-) as well as ESBL(+) were susceptible to imipenem and meropenem. 78.9% of ESBL(-) and 67.3% of investigated ESBL(+) were susceptible to piperacillin/ tazobactam.     

Proteus-typing by proticin production and susceptibility

A Proteus-typing method based on proticin production and proticin susceptibility (c.f. Senior, 1977) has been modified to increase its sensitivity. Proticins were prepared in fluid medium and applied to agar-plates shortly before seeding the plates with indicator bacteria. A given 10 proticin producer strains, which are responsible for the susceptibility patterns of the indicator-bacteria (S-types), form the foundation for this typing method. Using this producer-set an indicator-set (28 strains) was selected which was suitable for the typing of strains with different proticin activities (P-types). Standardization of the temperature for proticin production proved to be necessary. The degree of similarity between proticins was further elaborated by testing all indicator strains for susceptibility to proticin titrations. In the group of 148 clinical Proteus-isolates (four species) used for the development of the typing system 28 S-types and 34 P-types were observed. By combining the S- and P-type parameters 86 S-P-types were obtained for the 4 species combined. Seven strains were not typable. A separate group of 100 clinical Proteus-isolates was tested in order to prove the usefulness of the method. 39 new S-P-types were found. Repeated isolations from the same patients yielded the same patterns. Proteus S-P-typing is a useful method for the typing of Proteux vulgaris and Proteus mirabilis, but proves inadequate for the typing of Proteus rettgeri and Proteus morganii.     

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.     

Occurrence of beta-lactamase type ESBL and IBL in Pseudomonas aeruginosa rods]

The aim of the study was to determine extended spectrum beta-lactamases (ESBL) and inducible beta-lactamases (IBL) among Pseudomonas aeruginosa strains. A total of 43 strains isolated from humans (6), hospital sink (1), fish (15), cattle (5), swine (5), dog (1), redder (1) fur animals (9) were studied. ESBL-producing strains were detected with double disc diffusion test according to Jarlier et al. (8). Clavulonate and tazobactam were used as the inhibitors of ESBL. Inducible beta-lactamases were determined using double disc method according to Sanders (15). Cefoxitin was the inductor of these beta-lactamases. The susceptibility study was carried out using the disc diffusion method according to NCCLS standards. A total of 8 ESBL (18.6% of all strains) and 31 (72%) IBL producing strains were detected. The obtained results indicate the necessity of monitoring of ESBL- and IBL-producing strains of Pseudomonas aeruginosa.     

Resistance pattern of extended-spectrum beta-lactamase producing Enterobacteriaceae isolates

Gram-negative pathogens harboring extended-spectrum beta-lactamases (ESBL) are becoming an increasing therapeutic problem in many wards. The aim of our work was to study ESBL production by Enterobacteriaceae strains from Eastern Romania and their antimicrobial resistance. We selected 54 clinical isolates among 1068 enterobacteria according to their susceptibility spectrum (National Committee for Clinical Laboratory Standards, 1999). Antimicrobial susceptibility tests were performed using the Rapid ATB E gallery of mini API system (BioMérieux) and by a macrodilution method in Mueller-Hinton agar following standard procedure of the National Committee for Clinical Laboratory Standards (NCCLS). ESBL production was established by using both double disk synergy test (DDT) and Expert computer program of mini API. The isoelectric point (pI) was determined by isoelectric focusing in polyacrylamide gel and revealed by nitrocefin. As references we used beta-lactamases with known pI. The Expert computer program of mini API confirms the positive DDT test for all selected strains. Almost all strains displayed resistance to ampicillin, ampicillin/sulbactam or third generation cephalosporins and aztreonam. By IEF we identified 51 strains which have a unique enzyme. IEF pattern showed presence of two enzymes in three Escherichia coli strains. According to our results, the ESBL TEM-type are the most common for the studied isolates. The production of extended-spectrum beta-lactamases and the presence of the multiresistant of antimicrobial agents reflect, probably, the over use of third generation cephalosporins in Eastern Romania.     

Assessment of the susceptibility of the gram-negative rods isolated from hospitalized patients to cefoperazone/sulbactam

The susceptibility to cefoperazone/sulbactam of 197 strains of Gram-negative rods demonstrating an ESBL-positive phenotype was determined. The assortment of the investigated strains was as follows (numbers of strains are given in the brackets): E. cloacae (63), S. marcescens (46), K. pneumoniae (21), P. mirabilis (17), E. coli (9), P. vulgaris (8), P. aeruginosa (20) and A. baumanni (13). 83 strains from 197 were susceptible (42.1%). The MIC values were determined and the disc-diffusion method was performed. The susceptibilities among particular species were as follows (the order of data in the brackets is: % of the susceptible strains/MIC50/MIC90): E. cloacae (54.0/16/64), S. marcescens (23.9/64/> or = 128), K. pneumoniae (38.1/32/64), P. mirabilis (41.2/32/64), E. coli (44.4/32/32), P. vulgaris (75.0/8/32), P. aeruginosa (35.0/32/64), A. baumannii (46.2/32/64). Using disc-diffusion method, for 184 strains the difference between diameter of the inhibition zone around the disc with cefoperazone and the disc with cefoperazone/sulbactam was calculated. This difference amounted 5 mm or more in the case of 76.6% of the investigated strains. The results indicate that the comparison of the inhibition zones around cefoperazone and cefoperazone/sulbactam discs may be an additional method useful for phenotypic detection of ESBL producing organisms. These results highly correlated with results obtained by using analogous test with cefpirome and cefpirome/clavulanic acid (85.6% of concordance).     

First description of Escherichia coli producing CTX-M-15- extended spectrum - lactamases (ESBL) in outpatients from south-eastern Nigeria

ABSTRACT: We studied the presence of extended spectrum beta lactamases (ESBLs) in 44 clinical isolates of Escherichia coli collected from two university teaching hospitals in South-Eastern Nigeria. Species identification was performed by standard microbiology methods and re-confirmed by MALDI-TOF technology. Phenotypic characterization of ESBL enzymes was done by double disc synergy test and presence of ESBL genes was determined by specific PCR followed by sequencing. Transfer of plasmid DNA was carried out by transformation using E. coli DH5 alpha as recipient strain. Phenotypic characterization identified all isolates to be ESBL positive. 77% of strains were from urine, 13.6% from vaginal swabs and 9.0% from wound swabs. 63.6% were from female patients, 68% were from outpatients and 95.5% from patients younger than 30 years. All ESBL producers were positive in a PCR for blaCTX-M-1 cluster, in exemplary strains blaCTX-M-15 was found by sequencing. In all strains ISEcp1 was found upstream and ORF477 downstream of blaCTX-M. PCR for blaTEM and blaOXA-1 was positive in 93.1% of strains, whereas blaSHV was not detected, aac(6')-Ib-cr was found in 97.7% of strains. RAPD analysis revealed seven different clonal groups named A through G with the majority of the strains (65.9%) belonging to clone A. Transfer of an ESBL plasmid with co-resistance to gentamicin, kanamycin, tobramycin, doxycycline and trimethropim-sulfamethoxazole was successful in 19 (43.2%) strains. This study showed a high rate of CTX-M-1 cluster - ESBLs in South-Eastern Nigeria and further confirms the worldwide spread of CTX-M ESBL in clinical isolates. KEYWORDS: Outpatients, ESBL, CTX-M, Escherichia coli.     

Multidrug resistance to antibacterial drugs of Salmonella enterica subsp. enterica strains isolated in Poland in the 1998-1999 period]

A total of 510 Salmonella enterica subsp. enterica strains representing 56 serotypes, isolated from human stool specimens during 1998-2000 in sanitary-epidemiological units in Poland were tested for their susceptibility by a standard disk diffusion method for: ampicillin, cefotaxime, chloramphenicol, tetracycline, streptomycin, gentamicin, kanamycin, nalidixic acid, ciprofloxacin, furazolidone, cotrimoxazole, sulfonamides and trimethoprim. For 201 of the investigated strains, belonging to 5 most common isolated serotypes (S. Enteritidis, S. Typhimurium, S. Hadar, S. Infantis and S. Virchow) the minimal inhibitory concentrations (MICs) for the aforementioned antibiotics, as well as for amoxicillin with clavulanian were determined. Selected strains were screened for production extended spectrum b-lactamases (ESBLs). It was observed that 42.9% of Salmonella enterica subsp. enterica strains were resistant to 2 or more antibiotics, with the highest prevalence of MDR strains among serotypes Typhimurium, Hadar and Virchow. Resistance to ampicillin, streptomycin, tetracycline, nalidixic acid, furazolidone and sulphonamides was observed most frequently. Over 93% of S. Virchow strains were resistant to furazolidone. No strains resistant to ciprofloxacin were detected according to the NCCLS guidelines, but 31.3% of isolates exhibiting reduced ciprofloxacin susceptibility (MICs ranging between 0.125 and 0.5 mg/l). Two strains S. Mbandaka and Salmonella group D (variant motility--) were resistant to cefotaxime and probably produced ESBL.     

Susceptibility and frequency of selected groups of bacteria isolated in 2001 from patients at the Holy Cross Cancer Center

The aim of the presented study was the analysis of microbiological data obtained from patients hospitalized in The Holly Cross Cancer Center in Kielce in 2001. The frequency of important nosocomial pathogens in selected specimens and their susceptibility to antibiotics were determined. The strains were identified by using commercial tests (bioMerieux) and their antibiotic susceptibility patterns were performed by disc diffusion technique. The most prevalent bacteria were Gram-negative rods of Enterobacteriaceae family (43%), mainly Escherichia coli. Only 2.7% strains of isolated Escherichia coli isolated from clinical specimens collected from hospitalized patients were beta-lactamase--positive (ESBL+). The second important group of microorganisms were Staphylococci, followed by Enterococcus spp., Pseudomonas aeruginosa and Candida spp. About twenty eight percent of Staphylococcus aureus isolates were resistant to methicillin.     

Prevalence of rectal carriage of extended-spectrum beta-lactamase-producing Escherichia coli among elderly people in community settings in China

The importance of community-acquired infections due to extended-spectrum beta-lactamase-producing (ESBL) Escherichia coli has been increasingly recognized in recent years. No comprehensive data are available on the prevalence, risk factors, and genotypes of ESBL production in community residents in China. Rectal samples from 270 elderly people were collected in four communities in Shenyang (China). Colonies were screened by double-disk synergy test for ESBL production and then, ESBLs were characterized by PCR and sequencing. The clonal relatedness of all ESBL-producing isolates was determined by pulsed-field gel electrophoresis. Potential risk factors for rectal carriage of ESBL producers were examined by multivariate analysis. The prevalence of rectal carriage of ESBL-producing E. coli was 7.0%. All 19 ESBL-producing isolates produced CTX-M-type ESBLs, including CTX-M-14 (11 strains), CTX-M-22 (3 strains), CTX-M-79 (3 strains), CTX-M-24 (1 strain), and CTX-M-24 and CTX-M-79 together (1 strain). CTX-M-79 ESBL was first detected worldwide. ESBL-producing strains were clonally unrelated. Appearance of ESBL producers is strongly associated with the use of antibiotics in the past 3 months (odds ratio 3.2, 95% CI 1.1-9.0, P = 0.03). Our results show the importance of the intestinal tract as a reservoir for ESBL-producing isolates in community settings in China and that the use of antibiotics in the past 3 months is clearly linked to rectal carriage of ESBL producers.     

Prevalence of multidrug resistant and extended spectrum beta-lactamase producing Pseudomonas aeruginosa in a tertiary care hospital

Resistance to broad-spectrum beta-lactams, mediated by extended-spectrum beta-lactamase enzymes (ESBL), is an increasing problem worldwide. The present study was undertaken to determine the incidence of ESBL-production among the clinical isolates of Pseudomonas aeruginosa and their susceptibility to selected antimicrobials. A total of one eighty-seven clinical specimens were tested for the presence of ESBL production using the double-disc synergy test. Of these, 25.13% (n = 47) isolates of P. aeruginosa were observed as ESBL positive. The maximum number of ESBL-producing strains were found in sputum (41.67%; n = 24) followed by pus (28.36%; n = 19), cerebrospinal fluid and other body fluids (21.74%; n = 5), urine (20.45%; n = 9) and blood (13.79%; n = 4). ESBL producing isolates exhibited co-resistance to an array of antibiotics tested. Imipenem and meropenem can be suggested as the drugs of choice in our study.     

Long-Term Colonization by blaCTX-M-Harboring Escherichia coli in Healthy Japanese People Engaged in Food Handling

The actual state of intestinal long-term colonization by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in healthy Japanese people remains unclear. Therefore, a total of 4,314 fecal samples were collected from 2,563 food handlers from January 2010 to December 2011. Approximately 0.1 g of each fecal sample was inoculated onto a MacConkey agar plate containing cefotaxime (1 μg/ml). The bacterial colonies that grew on each plate were checked for ESBL production by the double-disk synergy test, as recommended by the Clinical and Laboratory Standards Institute. The bacterial serotype, antimicrobial susceptibility, pulsotype, sequence type (ST), and ESBL genotype were checked, and the replicon types of plasmids harboring the ESBL gene were also determined after conjugation experiments. ESBL producers were recovered from 70 (3.1%) of 2,230 participants who were checked only once. On the other hand, ESBL producers were isolated at least once from 52 (15.6%) of 333 participants who were checked more than twice, and 13 of the 52 participants carried ESBL producers for from more than 3 months to up to 2 years. Fluoroquinolone (FQ)-resistant E. coli strains harboring bla_CTX-M were repeatedly recovered from 11 of the 13 carriers of bla_CTX-M-harboring E. coli. A genetically related FQ-resistant E. coli O25b:H4-ST131 isolate harboring bla_CTX-M-27 was recovered from 4 of the 13 carriers for more than 6 months. Three FQ-resistant E. coli O1:H6-ST648 isolates that harbored bla_CTX-M-15 or bla_CTX-M-14 were recovered from 3 carriers. Moreover, multiple CTX-M-14- or CTX-M-15-producing E. coli isolates with different serotypes were recovered from 2 respective carriers. These findings predict a provable further spread of ESBL producers in both community and clinical settings.     

Trends in the Epidemiology of Pandemic and Non-pandemic Strains of Vibrio parahaemolyticus Isolated from Diarrheal Patients in Kolkata,India

A total of 178 strains of V. parahaemolyticus isolated from 13,607 acute diarrheal patients admitted in the Infectious Diseases Hospital, Kolkata has been examined for serovar prevalence, antimicrobial susceptibility and genetic traits with reference to virulence, and clonal lineages. Clinical symptoms and stool characteristics of V. parahaemolyticus infected patients were analyzed for their specific traits. The frequency of pandemic strains was 68%, as confirmed by group-specific PCR (GS-PCR). However, the prevalence of non-pandemic strains was comparatively low (32%). Serovars O3:K6 (19.7%), O1:K25 (18.5%), O1:KUT (11.2%) were more commonly found and other serovars such as O3:KUT (6.7%), O4:K8 (6.7%), and O2:K3 (4.5%) were newly detected in this region. The virulence gene tdh was most frequently detected in GS-PCR positive strains. There was no association between strain features and stool characteristics or clinical outcomes with reference to serovar, pandemic/non-pandemic or virulence profiles. Ampicillin and streptomycin resistance was constant throughout the study period and the MIC of ampicillin among selected strains ranged from 24 to >256 µg/ml. Susceptibility of these strains to ampicillin increased several fold in the presence of carbonyl cyanide-m-chlorophenyldrazone. The newly reported ESBL encoding gene from VPA0477 was found in all the strains, including the susceptible ones for ampicillin. However, none of the strains exhibited the β-lactamase as a phenotypic marker. In the analysis of pulsed-field gel electrophoresis (PFGE), the pandemic strains formed two different clades, with one containing the newly emerged pandemic strains in this region.     

Drug susceptibility of Pseudomonas aeruginosa strains isolated from patients of a hospital and specialistic outpatients clinics of the SP ZOZ in Nidzica

The aim of this study was to evaluate a frequency of isolation and antimicrobial susceptibility testing (AST) of Pseudomonas aeruginosa strains cultured from clinical specimens collected from patients hospitalized in wards and specialistic outpatients clinics of a hospital in Nidzica (01. 09. 2000 -31. 12. 2003). During over three years 392 Pseudomonas aeruginosa strains were cultured from 16346 clinical samples provided to bacteriological laboratory. P. aeruginosa strains were isolated from 2.5% of examined specimens. Susceptibility of Pseudomonas aeruginosa strains to antimicrobial agents was tested. The highest in vitro activity against clinical P. aeruginosa strains demonstrated imipenem. One strain was resistant to imipenem. This strain was isolated from a patient of a surgical department. Metalo-beta-lactamase was not detected (MBL-negative strain).Twenty nine strains were ESBL producer (7.4% of all strains). The contribution of Pseudomonas aeruginosa strains to the etiology of nosoconial and ambulatory infections increases. In vitro activity of antibacterial agents against P. aeruginosa strains should be monitored during therapy of infections. Resistance to antibiotics/chemothe-rapeutics may be acquired during treatment with antibacterial agent to which P. aeruginosa strain was susceptible according to the antibiogram.     

Metallo-beta-lactamase-producing gram-negative rods isolated from inpatients and outpatients, detected using Etest MBL

The aim of presented study was to detect MBL-positive strains in a group of clinical carbapenem-resistant strains isolated from inpatients and outpatients during last four years. From the beginning of November 2001 to the end of October 2005, one hundred and four strains resistant to carbapenem antibiotics--imipenem and meropenem were cultured from clinical samples obtained from patients of the Infant Jesus Clinical Hospital Centre for Trauma Treatment in Warsaw and from patients of outpatient clinics. Strains were identified and their susceptibility to antibacterial agents was determined in the automatic ATB Expression system (bioMérieux). Resistance to imipenem and meropenem was confirmed with a disc diffusion method. Production of metallo-beta-lactamases (MBL) was examined with the use of Etest MBL (AB Biodisk, Sweden), and extended-spectrum beta-lactamases (ESBL) by means of following procedures: DDST and / or DD (four variants) (Oxoid Ltd., England). MBL-positive strains (36) were cultured in cases of infections in adult patients (35 strains) and in a child (1 strain). Majority of strains belonged to the species P. aeruginosa (27), several strains - to the species P. putida (6) and remaining strains--to P. stutzeri, A. xylosoxidans, and E. cloacae (1 strain of each species). Four strains were producers of MBL-type and ESBL-type beta-lactamases. According to our knowledge and accessible literature described strains (except one paediatric strain) are the first MBL-positive strains isolated from adult hospitalized patients and adult ambulatory patients in Poland. Additionally, MBL-positive E. cloacae strain is probably the first MBL producer isolated in Poland, which belongs to the group of enteric rods. MBL-producing strains of Gram-negative rods, detected by phenotypic Etest MBL method, will be verified with genetic procedures.     

Infectivity and resistance to antibiotics of bacterial strains isolated from patients hospitalised in intensive care units

The aim of this study was to evaluate the frequency of isolation and antimicrobial resistance testing of bacterial strains isolated from clinical specimens from patients hospitalized in three Intensive Care Units in Wroc?aw. The susceptibility of bacteria (107 strains) to selected antibiotics was determined. The results clearly show that non-fermentative rods were identified as the main agents causing pneumonia (58% of isolates). The second commonest pathogens were Gram-positive cocci (29%). The P. aeruginosa and E. cloacae strains were resistant to ampicillin, amoxicillin/clavulanate, cefuroxime and cefotaxime. All isolates of A. baumanii were susceptible only to imipenem. The rods of K. pneumoniae and E. coli were resistant to ampicillin, about 55% strains of both bacteria were sensitive to other antibiotics, except piperacillin/tazobactam, imipenem and ciprofloxacin. About 90% of methicillin resistant S. epidermidis strains were resistant to all antibiotics, except vancomycin (100% isolates were sensitive). ESBL were detected among E. cloace, K. pneumoniae and E. coli. We found P. aeruginosa rods producing MBL.     

Prevalence of multidrug-resistant Proteus spp. strains in clinical specimens and their susceptibility to antibiotics

Proteus sp. are opportunistic microorganisms which cause urinary tract and wounds infections, bacteriaemia and sepsis. The aim of this study was analysis of prevalence of multidrug-resistant Proteus sp. strains in clinical specimens and evaluation of their susceptibility to selected antibiotics. The study was carried out of 1499 Proteus sp. strains were isolated in 2000-2003 from patients of departments and dispensaries of the University Hospital CM in Bydgoszcz UMK in Torun. The strains were identified on the basis of appearance of bacterial colonies on bloody and McConkey's agars, movement ability, indole and urease production and in questionable cases biochemical profile in ID GN or ID E (bio-Mérieux) tests was also included. Antibiotic susceptibility was tested by disk diffusion method. Isolated strains were regarded as multidrug-resistant when they were resistant to three kinds of antibiotics at least. Received Proteus sp. the most frequently belonged to P. mirabilis species (92.3%). Most of these bacteria were isolated from urine from patients of Rehabilitation Clinic. All of multidrug-resistant strains were resistant to penicillins and cephalosporins, 98.9% to co-trimoxazole, 77.7% to quinolones, 63.8% to tetracyclines, 38.5% to aminoglycosides, 19.3% to monobactams and 3.4% to carbapenems. Almost 25% multidrug-resistant Proteus sp. produced ESBL.