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Respiratory infections are the most frequent reason for primary health care consultation. The main causes of respiratory tract infections in children are viruses and the most common types are upper respiratory tract infections: common cold, pharyngitis, otitis media and sinusitis. Pneumonia is much more serious. As well as viruses, bacteria are often involved in respiratory tract infections. Three bacterial species are most commonly isolated: Streptococcus pneumoniae, non-encapsulated Haemophilus influenzae and Moraxella (Branhamella) catarrhalis. The most common bacterial cause of pharyngitis is Streptococcus pyogenes. Bacteria isolated from community-acquired infection usually are sensitive to the majority of suitable drugs, but during the past two decades, significant antibiotic resistance has emerged. Resistance to penicillins has spread among H. influenzae and S. pneumoniae. The mechanism of penicillin resistance in H. influenzae is mainly by production of beta-lactamases TEM-1 and ROB-1, whereas in S. pneumoniae resistance is an effect of the changes in penicillin binding proteins. Among respiratory pathogens, resistance to tetracyclines, macrolides, trimethoprim-sulphamethoxazole and fluoroquinolones has also appeared. Several mechanisms depending on changes in target, active efflux and modifying enzymes are involved.

For the study described in the paper, the effects of 10 days' chemotherapy with cefotaxime, clindamycin, mezlocillin, and piperacillin on local tumor growth and on spontaneous or artificial metastatic spread into the lungs were studied. For the animal tumor model Balb/c mice and the mouse sarcoma L-1 tumor were used. Chemotherapy was administered before, immediately after, or some time after the injection of tumor cells. The antibiotic dosage given to mice was calculated on a body weight basis from the doses recommended for humans. Cefotaxime and clindamycin did not influence the animal tumor model, whereas mezlocillin and piperacillin showed positive or negative effects depending on the chemotherapy schedule. In vitro none of the four antibiotics caused cytotoxic activity in cell cultures of mouse sarcoma L-1, human lung cancer E-14, or human malignant melanoma MEW.

Clumping reaction, using standard suspension of Staph. aureus Newman D-2-C strain and various substrates, was quantitatively tested. It has been shown that clumping occurs in fibrin lysate containing soluble fibrin monomer complexes unclottable by thrombin. The reaction was positive with staphylococcal strains possessing clumping factor regardless of staphylocoagulase production. Clumping reaction is similar to paracoagulation reaction induced by protamine sulfate. The substrate for both reactions is stable at 56°C but is destroyed at 60°C. The kinetics of substrate formation for both reactions during fibrin clot lysis is also similar. Clumping reaction with a strain of Staph. epidermidis possessing no clumping factor was positive when these bacteria were coated with protamine sulfate. The effect of heparin, sodium citrate, urea, 2-mercaptoethanol, merthiolate, and mucin on both reactions was tested. The present findings explain the clumping reaction in serum and emphasize the role of blood clotting and fibrinolytic systems in this phenomenon.

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