An observational study on the epidemiology of respiratory tract bacterial pathogens and their susceptibility to four injectable beta-lactam antibiotics: piperacillin, piperacillin/tazobactam, ceftazidime and ceftriaxone.

Bacterial infections of the respiratory tract account for a large proportion of total medical consultations in general practice. In recent years, antibiotic resistance has increased alarmingly in a number of bacterial species that are common causes of these infections. The aim of this observational study was to determine the antibiotic resistance of microbial agents isolated from patients with acute or acutely exacerbated respiratory infections. Subjects recruited as potential sources of bacteria were either outpatients seen in a number of specialized clinics and hospital practices, or hospitalized patients. Overall, 648 consecutive patients (67% male, mean age 48.1+/-27.0 years) with infection of the upper or lower respiratory tract were observed during a 13-month period. A total of 551 pathogenic microbial strains were isolated and tested for their in vitro susceptibility to piperacillin, piperacillin/tazobactam, ceftazidime, and ceftriaxone. Among all isolates, the four most frequent pathogens were Pseudomonas aeruginosa (132 isolates, 24%), Streptococcus pyogenes (99 isolates, 18%), Staphylococcus aureus (93 isolates, 17%), and Klebsiella pneumoniae (46 isolates, 8%). The susceptibility of gram-positive isolates ranged from 97.5% to 95.1%, and no remarkable difference was found in the antibacterial activity of tested b-lactam antibiotics. The susceptibility of gram-negative isolates to piperacillin and piperacillin/tazobactam was also similar: 96.5% and 97.1%, respectively. In contrast, differences were found between piperacillin (or piperacillin/tazobactam) and either ceftazidime (p=0.003) or ceftriaxone (p<0.0003) in gram-negative isolates. We conclude that, despite the extensive use of beta-lactam antibiotics (piperacillin, ceftazidime, and ceftriaxone) in medical practice during the past three decades, the susceptibility of the most common pathogens involved in the etiology of upper and lower respiratory tract infections to these antibiotics is still high. In particular, bacterial resistance developed by gram-positive organisms against piperacillin is negligible and not alarming.

In vitro antibacterial activity of men 10700, a new penem antibiotic.

We report here the antibacterial activity of the new penem antibiotic Men 10700 against a total of 740 gram-positive and gram-negative clinical isolates, in comparison to imipenem, meropenem, cefotaxime, ceftriaxone, ciprofloxacin and gentamicin. Men 10700 has shown a wide spectrum of antibacterial activity, with a potent activity both against gram-positive species (with the exception of methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis) as indicated by minimal inhibitory concentration (MIC(90)) values < or =0.5 mg/l, and gram-negative species, with MIC(90) values generally < or =2 mg/l. Men 10700 was the most potent antibiotic against methicillin-susceptible S. aureus and S. epidermidis, while the overall spectrum of activity resembled that of imipenem; meropenem was more active against most gram-negative species. In comparison with third-generation cephalosporins, Men 10700 demonstrated superior activity against methicillin-susceptible S. aureus and S. epidermidis and some gram-negative species such as Morganella morganii, Serratia spp. and Enterobacter cloacae; moreover, in contrast to third-generation cephalosporins, Men 10700 showed moderate activity against Enterococcus spp. The activity of Men 10700 against penicillin-resistant Streptococcus pneumoniae (10 strains) and some gram-negative strains selected for their resistance to cefotaxime (20 strains) was particularly interesting.

Antimicrobial resistance among clinical isolates of Haemophilus influenzae in northern Italy. Collaborative Study on Pediatric Infectious Diseases.

Only scanty data are available on the susceptibility of Haemophilus influenzae in Italy. The in vitro activity of ampicillin, ampicillin-sulbactam, cefaclor, cefuroxime, cefotaxime, chloramphenicol, erythromycin and trimethoprim-sulfamethoxazole against 327 strains of Haemophilus influenzae (55 encapsulated, 272 non-typeable) isolated from adults and children in northern Italy, between January 1984 and December 1989, was compared. Patients were affected by meningitis or other invasive infections, conjunctivitis, otitis, sinusitis, pneumonia or bronchitis. Minimal inhibiting concentrations were determined by a microdilution technique in Mueller Hinton broth supplemented with 10 microliters/ml NAD and 2-5% lysed horse blood. A concentration of 1 x 10(5) to 5 x 10(5) CFU/ml was used as the inoculum. The antibiotics were tested at concentrations ranging from 0.03 to 64 microliters/ml with the exception of trimethoprim-sulfamethoxazole, for which the range of concentrations examined were 0.01/0.25 to 32/512 microliters/ml. All the strains tested were susceptible to ampicillin-sulbactam, cefuroxime and cefotaxime, and more than 95% were susceptible to ampicillin, cefaclor and chloramphenicol. Only 4% were susceptible to erythromycin but most minimal inhibiting concentrations fell into the intermediate category. Strains isolated from adults were more susceptible to trimethoprim-sulfamethoxazole than strains isolated from children (85% vs 66%; p = 0.011).

In-vitro susceptibility of Haemophilus influenzae to loracarbef (LY 163892) and other oral antibiotics. Collaborative Study Group on Pediatric Infectious Disease in Lombardy.

Data on susceptibility of Haemophilus influenzae are scanty in Italy. We compared the activity of loracarbef (Ly 163892), a new carbacephem, with that of 4 other agents against 265 strains of H. influenzae (46 type b, 219 nontypable) isolated from adults and children at Istituti Clinici di Perfezionamento of Milano, between 1/1/84 and 1/1/89, and also from 7 children at pediatric departments in Lombardy during 1988. In adults 72 strains were all isolated from sputum of patients with pneumonia or chronic bronchitis; in children 199 strains were isolated from conjunctiva (53% of the patients had also a concomitant respiratory infection), 24 from middle ear, 18 from sputum and 32 from blood or cerebrospinal fluid. Minimal inhibiting concentrations (MIC) were determined by the broth microdilution technique. The incidence of resistance of H. influenzae to ampicillin was 3.8%; the lowest percentage of resistance was found for loracarbef (0%) and the highest for erythromycin (94% for strains isolated from children and 97% for strains isolated from adults).

In-vitro postantibiotic effects of miocamycin and erythromycin on gram-positive cocci.

The capability of miocamycin to induce a postantibiotic effect (PAE) on a Group A Streptococcus beta-haemolyticus clinical isolate and on Staphylococcus aureus ATCC 29213 has been studied. Erythromycin was chosen as a reference molecule. The exposure time to antibiotics was 90 min. The removal technique of the antibiotic agents consisted of a 1:200 dilution in cultural broth. Miocamycin displayed a PAE of 2 h 30 min in relation to the minimum inhibitory concentration (MIC) of Streptococcus and a PAE of 2 h 30 min in relation to the MIC of Staphylococcus. The PAE value lasting longer than the others was of 5 h 40 min towards Streptococcus and of 4 h 18 min towards Staphylococcus at a concentration eightfold the MIC. Erythromycin showed a PAE of 1 h 36 min in relation to the MIC of Streptococcus and a PAE of 1 h 30 min in relation to the MIC of Staphylococcus. The PAE value lasting longer than the others was of 3 h 15 min against Streptococcus and of 2 h 30 min against Staphylococcus at a concentration eightfold the MIC. In some cases a PAE was observed in relation to subinhibitory concentrations (1/2 MIC). Miocamycin therefore proved to possess a more evident capability to induce a PAE against the clinical isolate of Group A Streptococcus beta-haemolyticus and on Staphylococcus aureus ATCC 29213 than did erythromycin.

Clinical and microbiological evaluation of miocamycin activity against group A beta-hemolytic streptococci in pediatric patients. Three years' incidence of erythromycin-resistant group A streptococci.

The authors have evaluated the incidence of Group A streptococci, and the prevalence of erythromycin-resistant strains in the years 1985/86/87 at the I.C.P. of Milan. The minimum inhibitory concentrations (MICs) for erythromycin, penicillin and miocamycin of 40 erythromycin-resistant strains were also studied (MIC50-MIC90 = 4.5-8, 0.015-0.015, 0.041-0.186 micrograms/ml respectively). A clinical trial with miocamycin vs. erythromycin in the elimination of Group A streptococci (67 patients) showed good and comparable efficacy for both the antibiotics.

Treatment of lower urinary tract infections in children: single dose fosfomycin trometamol versus pipemidic acid.

Fifty-one children suffering from symptomatic and asymptomatic recurrent urinary tract infections were treated at random in a comparative study. A single dose of 2 g fosfomycin trometamol was administered to 24 children (2 males and 22 females, mean age 6.7 +/- 3.3 yr) and two 200 mg doses of pipemidic acid (400 mg in children weighing more than 25 kg) were administered daily to 27 children (3 males and 24 females, mean age 6.6 +/- 3 yr) for 7 days. Bacteriological results showed that at the end of followup (1 month) urine was sterile in 17 out of 24 children treated with fosfomycin trometamol (70.8%) and in 19 out of the 27 children treated with pipemidic acid (70.3%). One persistant infection and six reinfections were observed in the follow-up period in the fosfomycin group and 8 reinfections in the pipemidic acid group, usually in patients with urinary complications. No side effects were reported. The microbiological study of feces showed that neither of the drugs caused the emergence of resistant bacteria.

[Clinical use of latex tests. II. Evaluation of latex tests in C-reactive protein determination]. / L'impiego clinico dei tests al lattice. II. Valutazione dei metodi al lattice per la determinazione della proteina C reattiva (PCR).

We compared the most reliable and practical laboratory methods for the quantitative determination of serum C-reactive protein that is polistyrene latex particles together with purified anti-C-reactive protein rabbit globulin, the precipitation test using anti-C-reactive protein serum and finally, radial immunodiffusion on agar-gel plates. We examined 163 serum specimens from ambulatory patients and from various hospitalized patients in Istituti Clinici di Perfezionamento of Milan (Italy). All the methods tested showed a good qualitative discrimination for serum C-reactive protein presence or absence at pathological levels. We also compared the two latex methods. In conclusion, radial immunodiffusion confirmed to be the best method for accurate C-reactive protein dosage during inflammatory and degenerative processes.

[The clinical use of latex tests. I. Comparison of hemolytic and latex methods in the evaluation of the antistreptolysin antibody titer]. / L'impiego clinico dei tests al lattice. I. Confronto tra metodi emolitici ed al lattice nella valutazione del titolo anticorpale antistreptolisinico (TAS).

The TAS of 211 normo lipemic patients and of 84 hyperlipemic patients has been determined by the tube dilution hemolysis method of Rantz and Randall, the Aso Quantum hemolytic method (I.S.V.T. "Sclavo" S.p.A., Siena) and methods with streptolysin O antigen coated on the surface of biologically inert latex particles. A good correlation has been shown between all the analytical techniques considered and, moreover, the incidence of wrong positives and negatives has been showed in comparison with the hemolytic method by Rantz and Randall, considered test of reference. Finally, the greater influence of cholesterol on the classic hemolytic system, compared with the latex technique in causing an unspecific increase of TAS is proposed; this is evaluated before and after treatment of the hyperlipemic samples with ether.