[Beta-lactam-resistance patterns of some gram-negative rods]. / Wzory opornosci na antybiotyki beta-laktamowe niektórych paleczek gram-ujemnych.

Antibiotic susceptibility to ampicillin of 290 E. coli, 56 Klebsiella sp. And 167 P.mirabilis strains was evaluated by the disk diffusion method. Data were interpreted according to the NCCLS criteria. 37.9% of E. coli, 85.7% of Klebsiella sp. And 65.9% of P. mirabilis strains were resistant to ampicillin. In all resistant to ampicillin strains were performed resistance patterns to following antibiotics: piperacillin, amoxicillin/clavulanic acid, cefoxitin, cefuroxime, ceftazidime, cefotaxime and imipenem. The strains resistant to ampicillin were divided into four groups depending on resistance patterns.

[Susceptibility to cefazolin, cefamandole and ceftazidime in Staphylococcus strains]. / Wrazliwosc na cefazoline, cefamandol i ceftazydym metycylinowrazliwych i metycylinoopornych szczepów z rodzaju Staphylococcus.

365 S. aureus and 165 Coagulase Negative Staphylococci were tested for susceptibility to methicillin, cefazolin, cefamandole and ceftazidime by standard broth microdilution and disc method. In staphylococci resistance to methicillin normally parallels resistance to beta-lactams, and it has been suggested that cephalosporins are not be used clinically if susceptbility tests show resistance to methicillin. Populations of methicillin resistant staphylococci are made up of a mixture of methicillin-susceptible and methicillin-resistant cells (heteroresistant isolates). This phenomenon is the cause of differences in resistance in vitro to methicillin and tested cephalosporins. Cefamandole was the cephalosporin which retained most antibacterial activity against some methicillin-resistant isolates (MICm MRSA = 63.2 mg/L, MICm MRCNS = 67.4 mg/L). This antibiotic has extremely small resistant subpopulations, only detectable by high-inoculum screening or prolonged incubation of isolates in the presence of the drug. Cefazolin was the cephalosporin which had most antibacterial activity against all methicillin-susceptible isolates (MICm MSSA = 1.3 mg/L, MICm MSCNS = 1.6 mg/L). Among the 3 studied cephalosporins ceftazidime was found to be the least active against methicillin-resistant and methicillin-susceptible Staphylococci (MICm MSSA = 25 mg/L, MICm MRSA = 334.5 mg/L, MICm MRCNS = 414.6 mg/L, MICm MSCNS = 26.7 mg/L).

[Incidence of methicillin-resistant and methicillin-susceptible Staphylococcus strains in clinical materials]. / Czestosc wystepowania metycylinoopornych i metycylinowrazliwych szczepów z rodzaju Staphylococcus w materiale klinicznym.

365 S. aureus and 165 CNS were evaluated for susceptibility to methicillin. They were received from various clinic of Clinical Hospital in Bydgoszcz. The bacterial cells that grew in the presence of 25 mg methicillin/L were evaluated as methicillin-resistant. It was found that the 129 MRSA and MRCNS. Incidence depended on the kind of clinic and material. Most often they were isolated from clinic: Surgery, Neurosurgery, Intensive Care Unit, Neurology and Ortopedics. They were from: intubation tube, catheters and vascular grafts. The methicillin-resistant S. epidermidis and S. haemolyticus showed above 50% resistance to methicillin.

[Susceptibility to antibiotics of Staphylococcus aureus strains]. / Wrazliwosc na antybiotyki szczepów Staphylococcus aureus.

Staphylococcus aureus is a very important pathogen in humans about 20% of all bacterial infections are caused by S. aureus. Because the staphylococcal sensitivity patterns have changed, the aim of this study was to investigate the current susceptibility of the S. aureus strains to 9 antibiotics: penicillin (P), amoxacillin/clavulanic acid (AMC), erythromycin (E), cortimoxazole (SXT), tetracycline (T), chloramphenicol (C), mupirocin (MUP), gentamicin (Ge) and vancomycin (Va). Susceptibility testing was performed by disc diffusion technique, by the procedure outlined by the National Committe for Clinical Laboratory Standards (NCCLS). Susceptibility to methicillin was determined using 5 micrograms methicillin disks. beta-lactamase production in the penicillin-resistant strains was detected with nitrocefin impregnated disk (Cefinase, BBL Microbiology system). The microbiological characteristics of the samples: 338 of the isolates were derived, from noses and the throats 382--from surgical wound secretions. The analysis of the results showed that most S. aureus strains (82.8%) are penicillin resistant and beta-lactamase producing 13.5% of all strains were methicillin-resistant. 16.5%--were erythromycin resistant; 3.2%--were cotrimoxazole resistant; 51.4%--were mupirocin resistant; 20.6%--were gentamicin resistant. All of the strains were vancomycin sensitive.