An Analysis of Resistance Patterns of Oral Streptococci Obtained from Orofacial Infections Against Beta-lactams, Clindamycin and Vancomycin over 2014-2018.

PURPOSE: Comparison of viridans group Streptococcus (VGS) susceptibility to benzylpenicillin, ampicillin, clindamycin and vancomycin in order to determine resistance rates to assess whether guidelines for prophylactic or therapeutic antibiotic treatment include the present resistance patterns. MATERIALS AND METHODS: A retrospective analysis of antimicrobial susceptibility testing (AST) over 4 consecutive years (2014-2017) and 4 months in 2018 for 779 VGS isolates (cumulative data). Isolates originated from pus from orofacial infections cases and tissue fragments from patients undergoing maxillofacial surgeries Results: The highest resistance rate was observed to clindamycin. The highest overall resistance rate was for Streptococcus parasanguinis 43% and S. constellatus 49%; the lowest was for S. anginosus 12%. All S. anginosus isolates were susceptible to ampicillin during tested period. All isolates of analysed species were susceptible to vancomycin through studied period. CONCLUSION: Due to high resistance levels, individual antibiotic susceptibility testing for strains should become mandatory.

Corynebacterium coyleae as potential urinary tract pathogen.

Corynebacterium coyleae is part of the commensal microflora of the skin, urethra, mucous membranes, and genital tract. Isolates from patients with urinary tract infection (UTI) were reported, but the pathogenic potential of this species has not been defined yet. The aim of the study is to determine whether C. coyleae could be the etiological agent of UTI and to analyze its antibiotic susceptibility. Urine samples were cultured quantitatively according to accepted laboratory procedures. The identification of bacterial isolates was carried out using the Vitek MS (bioMérieux) and antibiotic susceptibility was tested using disc diffusion according to EUCAST guidelines. Between 1 January 2017 and 30 October 2018, a total of 39 C. coyleae strains were isolated. This represented 0.32% of all urine samples cultured in the laboratory during the collection period. The strains were isolated from samples obtained from 35 women and 3 men (age median for all-64 years). One female patient presented with C. coyleae in her urine twice at an interval of 21 months. In six cases of UTI, C. coyleae was isolated in monoculture. The isolates had the same resistance pattern. A total of 11 strains were obtained from cases with a clinical diagnosis of UTI. In 13 cases, the strain was cultured in a monoculture and in 28 cases with accompanying species. All strains were susceptible to vancomycin. However, resistance to ciprofloxacin was observed for 58.4% of the strains. Urine isolates of C. coyleae must be considered as contamination or normal flora in most cases (28/39, 72%). In the remaining cases, it can be considered as potential etiologic agents, mostly in women and especially in the 6 UTI cases where C. coyleae was found as the single culture-positive species. Several of these isolates demonstrate resistance to antibiotics commonly used in empiric treatment of urinary tract infections.

The presence of antibiotic resistance genes and bft genes as well as antibiotic susceptibility testing of Bacteroides fragilis strains isolated from inpatients of the Infant Jesus Teaching Hospital, Warsaw during 2007-2012.

The purpose of this study was to assess drug susceptibility of clinical B. fragilis strains and to determine any correlation between drug resistance and the presence of specific genes. Antimicrobial susceptibility was assessed using E-tests. All isolates were analyzed with the PCR technique for the presence of antibiotic resistance genes (cepA, cfxA, cfiA, ermF, ermB, ermG, nim), insertion sequences elements (IS1186, IS1187, IS1188, IS942), and enterotoxin-encoding genes (bft). Susceptibility tests yielded the following rates of resistance to the evaluated antibiotics: penicillin G (100%), clindamycin (22.5%), cefoxitin (6.3%), amoxicillin/clavulanic acid (1.8%). All strain were susceptible to imipenem, and metronidazole. The following antibiotic resistance genes were detected in the evaluated isolates: cepA (in 96.4% of isolates), cfxA (in 12.6%), cfiA (in 1.8%), and ermF (in 25.2%). Genes ermB, ermG, and nim were not found. The presence of the cepA gene showed no correlation with the penicillin G MIC. However, we observed a high correlation between cefoxitin MIC values and the presence of gene cfxA as well as a nearly complete correlation between clindamycin MIC values and the presence of gene ermF. The presence of a bft gene was detected in 14.4% of the analyzed B. fragilis isolates; with the bft-1 allele found in 75%, bft-2 in 25%, and bft-3 in none of the isolates. Antibiotic susceptibility profiles of enterotoxin gene-positive isolates in our study did not differ from those of enterotoxin gene-negative isolates.

Difficulties in identifying the bacterial species from the genus Clostridium in a case of injury-related osteitis.

Most Clostridium species are part of saprophytic microflora in humans and animals; however, some are well-known human pathogens. We presented the challenges in identifying the Clostridium species isolated from a patient with an infected open dislocation of the proximal interphalangeal joint of the fourth digit of the right hand. The clinical materials were intraoperative samples collected from a patient diagnosed with an injury-related infection, with soft tissue loss and tendon sheath involvement. The available biochemical, molecular, and genetic techniques were used in identifying the isolated bacteria. The isolated bacterium was shown to have low biochemical activity; hence, it was not definitively identified via biochemical tests Api 20A or Rapid 32A. Vitek 2 and mass spectrometry methods were equally inconclusive. Clostridium tetani infection was strongly suspected based on the bacterium's morphology and the appearance of its colonies on solid media. It was only via the 16S rRNA sequencing method, which is non-routine and unavailable in most clinical laboratories, that this pathogen was excluded. Despite appropriate pre-laboratory procedures, which are critical for obtaining reliable test results, the routine methods of anaerobic bacterium identification are not always useful in diagnostics. Diagnostic difficulties occur in the case of environment-derived bacteria of low or not fully understood biological activity, which are absent from databases of automatic bacterial identification systems.

In vitro effect of clindamycin against Bacteroides and Parabacteroides isolates in Poland.

OBJECTIVES: The aims of this study were (i) to analyse strains of the genera Bacteroides and Parabacteroides isolated from clinical specimens for phenotypic resistance to clindamycin, (ii) to detect erm genes in the isolates and (iii) to determine any correlation between in vitro resistance and the presence of erm genes. METHODS: The Bacteroides and Parabacteroides isolates analysed were obtained from patients hospitalised at teaching hospitals in Poland. Antimicrobial susceptibility testing was performed by Etest and the results were interpreted according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. All isolates were analysed by PCR for the presence of the resistance genes ermF, ermB and ermG. RESULTS: Resistance to clindamycin was detected in 31.0% (62/200) of all evaluated isolates, with the ermF and ermB genes detected in 31.0% (62/200) and 0.5% (1/200) of isolates, respectively. No isolates with ermG were detected among the evaluated strains. Pearson's test showed an almost perfect correlation between clindamycin minimum inhibitory concentrations (MICs) and the presence of ermF in Bacteroides spp. and Parabacteroides distasonis isolates, although the ermF gene was also present in 10 clindamycin-susceptible isolates of Bacteroides spp. CONCLUSIONS: This study demonstrated a substantial proportion of Bacteroides (22.5-100% depending on the species) and 50.0% of Parabacteroides strains exhibiting resistance to clindamycin. The clindamycin MIC for resistant strains in each case was ≥256mg/L. Resistance to clindamycin in Bacteroides and Parabacteroides species is correlated mainly with the presence of the ermF gene.

Erythromycin or Clindamycin - is it Still an Empirical Therapy against Streptococcus agalactiae in Patients Allergic to Penicillin?

Retrospective analysis of Streptococcus agalactiae antibiotic susceptibility isolated in 2010-2013 was performed. Penicillin was still the first-line antibiotic. Due to the high percentage of strains resistant to erythromycin and clindamycin empirical treatment with these antibiotics may not be effective. Lower resistance rate to erythromycin and clindamycin among strains isolated from infected pregnant women and newborns were observed than among strains isolated from samples from patients hospitalized in other departments (29% and 47% v. 46% and 63%). The increasing resistance rate might give a rise to a new epidemiological situation.

Orthopedic infections caused by obligatory anaerobic Gram-negative rods: report of two cases.

Anaerobic bone and joint infections are uncommon, although the number of anaerobic infections is presumably underestimated because of difficulties with isolation and identification of obligate anaerobes. This study describes two cases of complicated Bacteroides fragilis peri-implant infection of the lumbar spine, infection of the hip and osteomyelitis. Bacteria were identified with the use of a mass spectrometer, VITEK MS system. Drug susceptibility was performed with the use of E-test. The EUCAST breakpoints were used for interpretation with B. fragilis ATCC 25285 as a control. In the two described cases clinical samples were collected for microbiological examination intraoperatively and simultaneously empirical treatment was applied. B. fragilis was isolated in monoculture or in a combination with other bacteria. The treatment was continued according to the susceptibility tests. In a case one clindamycin failure was observed and clindamycin resistance of the isolate was likely due to inadequate time of therapy. Difficulties in collecting an adequate samples and culturing anaerobic bacteria cause that not all infections are properly recognized. In a successful therapy, identification and determination of the susceptibility of the pathogen are essential as well as an appropriate surgical debridement.

[Microbiologic spectrum and susceptibility of bacteria isolated from patients with intra-abdominal infection].

the analyzed peritoneal fluid and bile specimens were comparable. Multiple bacterial species were significantly more common in bile isolates than in peritoneal fluid isolates. A total of 61,7% of aerobic Gram-negative bacillus isolates obtained from peritoneal fluid and bile produced ESBL. The proportions of vancomycin-resistant enterococci (VRE) and enterococci exhibiting high-level aminoglycoside resistance (HLAR) were 32,6% and 43,5%, respectively. Ertapenem-resistant K. pneumoniae was detected in 22,2% of peritoneal fluid cultures and 71,4% of biliary cultures. Methicillin resistance was detected in 85,7% of staphylococcal isolates. The proportion of anaerobes detected in peritoneal fluids was relatively high at approximately 17% and included predominantly Gram- negative species. All Gram-negative anaerobes showed resistance to benzylpenicillin. Conclusions: Etiologies and susceptibility pattern of IAls must be monitored on a ward, hospital, regional, and world-wide scale and the findings implemented into epidemiologic surveillance programs and proposed treatment protocols.

Surgical site infections after kidney transplantation--where do we stand now?

BACKGROUND: Kidney transplantation (KTx) is a widely accepted method of renal function replacement therapy. Surgical site infections (SSIs), along with urinary tract infections, are among the most common infective complications after KTx. The purpose of this study was to assess the incidence of SSI in patients after KTx, identify risk factors for SSI, and classify patients in which standard antibiotic prophylaxis could be avoided. METHODS: Between January 2010 and December 2011, 262 KTxs were performed in our center. Deceased donors', recipients' data, and data related to surgical procedures were collected. SSIs were diagnosed in accordance with the guidelines published by the U.S. Centers for Disease Control and Prevention. RESULTS: SSIs were diagnosed in 7.25% (19/262) of patients. Of nineteen SSI patients, two (10.5%) were diagnosed with organ-specific SSIs, which eventually led to graft loss; six (31.5%) developed deep incisional SSIs; and eleven (58%) developed superficial incisional SSIs. Through analysis of this extensive data set, we determined the following risk factors for the development of SSI: kidney from extended criteria donors, a cold ischemia time of more than 30 hr, time of surgical procedure longer than 200 min, confirmed diabetes in the recipients, a recipient body mass index higher than 27 kg/m, and occurrence of delayed graft function. CONCLUSIONS: It may be possible to reduce standard antibiotic prophylaxis to a single dose in patients without known risk factors for SSI. Any opportunity to reduce antibiotic use is crucial in preventing the development of multi-drug-resistant pathogens.

A comparison of Api 20A vs MALDI-TOF MS for routine identification of clinically significant anaerobic bacterial strains to the species level.

Adequate identification of anaerobic bacteria still presents a challenge for laboratories conducting microbiological diagnostics. The aim of this study was to compare the use of Api 20A and MALDI-TOF MS techniques for identification of obligate anaerobes. The results indicate that MALDI-TOF MS ensures a rapid and accurate identification of the species isolated from patients.

[Specificity of the anaerobic bacterial infections in the surgical and orthopedic wards]. / Specyfika zakazen bakteriami beztlenowymi na oddzialach chirurgicznych i ortopedycznych.

INTRODUCTION: The aim of this study was to estimate the contribution strictly anaerobic bacteria in the etiology of infections in patients on surgery and orthopedic wards. METHODS: We examined 159 samples taken from patients hospitalized in surgical wards and 179 clinical specimens taken from orthopedic patients. Clinical strains of obligate anaerobes were identified by API 20A biochemical tests (ATB Expression, bioMerieux S.A., France). Susceptibility of the clinical strains was examined by ATB ANA (bioMerieux S.A., France) system. The MIC values were determined by the gradient diffusion method, Etest (AB BIODISK, Sweden i bioMerieux S.A., France). RESULTS: Gram-negative bacteria predominant in the samples taken from surgical patients, Most frequently we isolated rods of the genus Bacteroides (26%): B. fragilis, B. ovatus/B. thetaiotaomicron, and B. distasonis. In 44 samples (28%) we identified only anaerobic bacteria. Multibacterial isolations, with the participation of anaerobic and aerobic flora, dominated among patients in the study. Overall 238 strictly anaerobic bacteria were cultured from patients hospitalized in orthopedic wards. Gram-positive bacteria accounted for 78%. The most frequently were isolated Peptostreptococcus (56%), Propionibacterium (10%) species. In this study all Bacteroides strains were resistant to penicillin G. Some species were resistant to clindamycin, as well. Overall 40% of Bacteroides strains taken from surgical and 50% isolated from orthopedic wards showed no sensitivity to this antibiotic. A similar phenomenon was observed among bacteria of the genus Prevotella. CONCLUSIONS: In samples taken from orthopedic patients we observed the predominance of Gram-positive anaerobic bacteria. Some of them were part of the normal flora but they should not be excluded as an etiology agents of infection. The specimens taken from patients treated in surgical wards showed the presence of a mixed microflora, which included aerobic and anaerobic bacteria, primarily Gram-negative rods. Rational empirical therapy of infections with anaerobes should be mainly based on the resistance pattern in each ward and hospital. In view of the increasing in the number of resistant strains is necessary to monitor drug resistance of anaerobic bacteria.

[Participation of gram-negative anaerobes in infections in hospitalized patients]. / Udzial beztlenowych Gram-ujemnych bakterii w zakazeniach hospitalizowanych pacjentów.

The aim of the study was to assess the prevalence and antibiotic susceptibility profiles of strictly anaerobic Gram-negative bacteria isolated from clinical samples taken from hospitalized patients from 01.01.2007 to 31.12.2008. The specimens were cultured using media, incubated at 37 degrees C under anaerobic conditions. Biochemical identification and antibiotic susceptibility were done in an automated system ATB Expression (bioMerieux S.A, France). For selected strains of Bacteroides sp. sensitivity was determined using E-test (AB BIODISK, Sweden). Overall 1274 strains of obligate anaerobes were isolated. Gram-negative bacteria were cultured in number of 333 strains. Most frequently isolated was Bacteroides sp. (46,9%) and Prevotella sp. (29,7%). Isolated bacteria are still susceptible to imipenem (100%), metronidazole (100%) and beta-lactam antibiotics with beta-lactamase inhibitors: amoxicillin/clavulanate (97,8%) piperacillin/tazobactam (99,1%), ticarcillin/clavulanate (99,1%).

Bacterial infections in the early period after liver transplantation: etiological agents and their susceptibility.

BACKGROUND: The study comprises an analysis of bacterial infections in the early period after liver transplantation (LT) in adults. MATERIAL/METHODS: Eighty-three patients were followed for four weeks after LT. Samples comprised mainly blood, urine, surgical-site specimens, sputum, and stool. Culture and identification of the isolated microorganisms was done in accordance with standard microbiological procedures. Susceptibility testing was carried out using CLSI guidelines. Statistical analysis was done with Medi-Stat. RESULTS: In total, 913 samples from LT recipients were cultured. Of the 469 isolated strains, 331 (70.6%) were Gram-positive bacteria, 133 (28.4%) were Gram-negative bacteria, and 5 (1.0%) were yeast-like fungal strains. Of the 284 surgical-site isolates, 222 (78%) were Gram-positive and 61 (21.5%) were Gram-negative bacteria. Of the 99 blood culture isolates, 75 (75.8%) were Gram-positive and 22 (22.2%) of Gram-negative bacterial strains. Of the 73 urine samples, 46 (63.0%) were strains of Gram-negative, 25 (34.0%) of Gram-positive bacteria, and 2 (3.0%) fungal strains. In the 13 respiratory tract samples were 9 (69.0%) Gram-positive and 4 (31.0%) Gram-negative strains. In the 54 stool samples, 63.0% and 16.7% were C. difficile toxin- and culture-positive, respectively. In total, 138 strains of MRCNS, 10 of MRSA, 80 of HLAR, and 19 ESBL(+) were detected. CONCLUSIONS: The isolation of MDR bacterial strains such as MRSA (52.6%), MRCNS (81.7%), HLAR (86.0%), and ESBL(+) Gram-negative rods (12.5%) from patients after LT indicates the need for strict adherence to infection control procedures.

[Enterobacter cloacae--antimicrobial susceptibility of strains isolated from hospitalized patients in 2004-2005]. / Enterobacter cloacae--wrazliwosc na antybiotyki szczepów izolowanych od chorych hospitalizowanych w latach 2004-2005.

The profiles of resistance of ESBL(-) and ESBL(+) strains of Enterobacter cloacae were analysed and compared. 466 Enterobacter cloacae strains isolated from different specimens obtained from patients of big Warsaw hospital in 2004-2005 were investigated. By using the several phenotypic methods 33.5% of strains was identified as ESBL(+). ESBL(+) strains were significantly less susceptible then ESBL(-). These two groups differed mostly in susceptibility to aminoglycosides and fluoroquinolones, e.g. 65.5% of ESBL(-) strains were susceptible to gentamicin, compared to only 25.0% ESBL(+), in case of ciprofloxacin 59.0% of ESBL(-) were susceptible whereas only 25.0% of ESBL(+) strains. The percentage of ESBL(+) grew from 26.4% in 2004 to 40.4% in 2005, whereas a tendency of growing susceptibility to aminoglycosides and fluoroquinolones was noted among all E.cloacae strains. Susceptibility to combinations of piperacillin or ticarcillin with beta-lactamase inhibitor was rather low among ESBL(+) strains.

Biofilm production by clinical strains of Acinetobacter baumannii isolated from patients hospitalized in two tertiary care hospitals.

Microbial biofilms are considered as virulence factors. During the present study, 34 clinical strains of Acinetobacter baumannii, isolated from patients hospitalized in two tertiary care hospitals, were examined for biofilm formation. These strains showed high variability in biofilm formation. Furthermore, no relation could be found between the ability of biofilm production and molecular type, carbapenem resistance, site of isolation of the clinical strains of A. baumannii and disease severity. Interestingly, in two cases an increase in biofilm formation could be detected in A. baumannii isolates cultured from the same patient upon prolonged hospitalization.

[Characteristic of clinical strains of gram-negative obligate anaerobes]. / Charakterystyka klinicznych szczepów gram-ujemnych bezwzglednych beztlenowców.

The aim of the study was to assess prevalence and antibiotic susceptibility profiles ofGram-negative strictly anaerobic bacteria isolated from clinical specimens taken from hospitalized patients in 2005-2006. Biochemical identification and antibiotic susceptibility were done in an automated system ATB Expression (bioMerieux sa). From 12262 specimens examined 867 strains of obligate anaerobes were isolated. Gram-negative strictly anaerobic bacteria were cultured in number of 138 strains (15,9%). All cultures were performed on Columbia agar and Schaedler agar media (bioMerieux sa) supplemented with 5% sheep blood and incubated at 37 degrees C for 48-120 h in 85% N2, 10% H2, 5% CO2. Most frequently isolated was Bacteroides spp. (41,3%). For this group beta-lactamase activity was evaluated by using nitrocefin disc test (Cefinase BBL, Becton Dickinson and Co., Cockeysville, MD, USA). Production of ESBLs was detected with the use of two disc diffusion methods: the double-disc synergy test (DDST) according to Jarlier et al. and the diagnostic disc (DD) test according to Appleton. ESBLs were produced by 5,3% strains of Bacteroides spp. For all Bacteroides spp. strains MIC values were determined by gradient diffusion method Etest (AB BIODISK, Sweden). ESBLs and MIC were performed on Wilkins-Chalgren solid medium supplemented with 5% sheep blood (Difco Lab., USA) and all plates were incubated at 35 degrees C for 48 hours in 85% N2, 10% H2, 5% CO2. Most Gram-negative obligate anaerobes isolated from clinical specimens are still susceptible to imipenem (100%), metronidazole (99,3%) and beta-lactam antibiotics with beta-lactamase inhibitors: piperacillin/tazobactam (99,3%), ticarcillin/clavulanate (99.3%), amoxicillin/clavulanate (97.8%).

[Metallo-beta-lactamase-producing gram-negative rods isolated from inpatients and outpatients, detected using Etest MBL]. / Paleczki gram-ujemne wytwarzajace metalo-beta-laktamazy izolowane od pacjentów szpitalnych i pozaszpitalnych, wykryte przy zastosowaniu metody 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.

[Role of obligate anaerobes in infections in hospitalized patients and therapeutic options]. / Udzial bakterii bezwzglednie beztlenowych w zakazeniach u hospitalizowanych pacjentów i mozliwosci terapii tych zakazen.

Monitoring of prevalence and antibiotic susceptibility of strictly anaerobic bacteria, causing infections in hospitalized patients, constitutes a part of a program for prudent use of antibiotics. The aim of the study was to assess prevalence of strictly anaerobic bacteria in patients hospitalized in a tertiary care hospital in 2001-2002 with reference to empiric antibiotic therapy. The most common gram-positive bacteria were Clostridium difficile--27.7%, Peptostreptococcus spp. and Peptoniphilus asaccharolyticus--21.9% and Actinomyces spp.--11.1%. There was an increase in the number of stool samples positive for C. difficile toxins A and B from 39.4% in 2001 to 59.0% in 2002. The results of susceptibility testing of gram-positive isolates showed the highest percentages of strains susceptible to piperacilin/tazobactam--99.6%, ticarcillin/clavulanate--98.5%, imipenem--98.5%, amoxicillin/clavulanate--97.4% and piperacillin--97.4%. The most prevalent gram-negative anaerobes were strains of Bacteroides spp.--43.1%, Prevotella spp.--35.8% and Fusobacterium spp.--11.0%. All tested strains of gram-negative bacteria were susceptible to metronidazole, piperacilin/tazobactam, ticarcillin/clavulanate and imipenem. In the analyzed population beta-lactam antibiotics with beta-lactamase inhibitors, carbapenems and metronidazole may be used in empiric therapy of infections caused by strictly anaerobic bacteria.

[Application of four variants of the diagnostic disc test (CD01, CD02, CD03, CD04) for detection of ESBL-positive strains of gram-negative rods]. / Zastosowanie czterech wariantów testu krazka diagnostycznego (CD01, CD02, CD03, CD04) do wykrywania ESBL-dodatnich szczepów gram-ujemnych paleczek.

The aim of this study was to evaluate the usefulness of four variants of the diagnostic disc test (DD) to detect extended-spectrum beta-lactamases (ESBLs) in nosocomial strains of gram-negative rods. Also, the diagnostic disc test (DD) was compared with the double-disc synergy test (DDST) for the effectivity of ESBLs identification. A total number of 111 ESBL-positive (DDST-positive) strains of gram-negative rods isolated from hospitalized patients in 2004 was examined. Ninety nine strains belonged to enteric rods (89.2%) and twelve strains--to nonfermentative rods (10.8%). Two reference strains: E. coli ATCC 25922 (ESBL-negative one) and K. pneumoniae ATCC 700603 (ESBL-positive one) were included in the study. Four variants of the diagnostic disc test (DD, Oxoid Ltd, UK) were applied for ESBLs detection: CPD/CD01, CAZ/CD02, CTX/CD03 and CPO/CD04. All examined strains (111) were DDST-positive. Positive results in the DD test (Oxoid Ltd) were as follows: CPD/CD01--59 strains (53.2%), CAZ/CD02--80 strains (72.1%), CTX/CD03--92 strains (82.9%) and CPO/CD04--110 strains (99.1%). Discs containing cefpirome (CPO) and cefpirome with clavulanic acid (CD04) were the best set for detection of ESBLs in our collection of clinical gram-negative rods. Results of this variant of the DD test were the most consistent with the results of the DDST. Application of several disc diffusion methods to detect ESBL producers increases the probability of proper identification of these strains.