José Romero-Vivas

Bacteremic Pneumonia Due to Staphylococcus aureus: A Comparison of Disease Caused by Methicillin-Resistant and Methicillin-Susceptible Organisms

We performed a prospective study of all patients with bacteremic pneumonia due to Staphylococcus aureus over a period of 6 years during an outbreak of methicillin-resistant S. aureus (MRSA). Patients with bacteremic pneumonia due to MRSA (32 cases) or methicillin-susceptible S. aureus (MSSA; 54 cases) were compared. The patients with MRSA pneumonia were older and were more likely than those with MSSA pneumonia to have predisposing factors for acquisition of the infection. There were no differences in clinical findings, radiological pattern, or complications in clinical evolution among patients with MRSA and MSSA pneumonia. Mortality was significantly higher among MSSA-infected patients treated with vancomycin than among those treated with cloxacillin (47% vs. none; P<.01). Multivariate analysis (stepwise logistic regression method) showed a relationship between mortality and the following variables: septic shock (odds ratio [OR], 61), vancomycin treatment (OR, 14), and respiratory distress (OR, 8).

Staphylococcus aureus bacteremic pneumonia: differences between community and nosocomial acquisition

OBJECTIVE The aim of the study was to ascertain the clinical and epidemiologic characteristics of patients with nosocomial or community-acquired Staphylococcus aureus bacteremic pneumonia. METHODS A prospective study of 134 cases diagnosed between January 1990 and December 1995 was performed. RESULTS Fifty cases involved primary bacteremic pneumonias, of which 80% were nosocomial (the majority, 72%, in intensive care unit patients, of whom 57% were post-surgery). Of the 84 cases of secondary pneumonia, 36 were non-intravenous drug users (78% nosocomial, of whom 43% were in the intensive care unit), and 48 cases were intravenous drug users (98% community-acquired). CONCLUSIONS Nosocomial S. aureus bacteremic pneumonia was especially frequent in intensive care unit patients (68.1%), and community-acquired pneumonia in intravenous drug users (72.3%). In non-intravenous drug users, clinical outcome and mortality were similar for nosocomial and community-acquired pneumonia.

Evaluation of aztreonam in the treatment of severe bacterial infections.

We investigated the clinical efficacy and safety of aztreonam in the treatment of 50 episodes of infection in 46 adult patients. The clinical condition of patients at the beginning of treatment was critical or poor in 28 of the episodes of infection. Episodes treated were 39 urinary tract infections (12 of them with concomitant bacteremia), 2 soft tissue infections, 8 patients with osteomyelitis (1 with concomitant bacteremia), and one episode of pneumonia. Significant isolated microorganisms were aerobic or facultative gram-negative rods and were responsible for the following episodes of infection (number of episodes): members of the family Enterobacteriaceae (49), Pseudomonas aeruginosa (5), and Haemophilus influenzae (1). The overall rate of clinical response to aztreonam was 94% of the treated episodes. Colonization or superinfection or both occurred in 29 episodes, but only 8 episodes required antimicrobial therapy. Aztreonam seems to be an effective single agent therapy for many bacterial infections. Colonization and superinfection by Candida sp., Streptococcus faecalis or Staphylococcus aureus must be monitored.

Temocillin. In vitro activity compared with other antibiotics.

Temocillin is a recently developed penicillin with a methoxy group in the 6-alpha position. The in vitro activity of temocillin was studied using 932 recent clinical isolates of aerobic and anaerobic Gram-negative bacilli and Gram-positive cocci, and its activity was compared with that of other beta-lactam antibiotics. Temocillin was active against the Enterobacteriaceae, with narrow ranges of MICs and MIC90 values (less than or equal to 8 mg/L) for all isolates except Serratia marcescens and Enterobacter species. Moreover, the compound was active against 46 multiresistant Enterobacteriaceae strains. The drug was also strongly active against Haemophilus influenzae, with beta-lactamase-producing strains being as susceptible as non-beta-lactamase-producing strains. Temocillin showed no useful activity against Pseudomonas aeruginosa, Acinetobacter or Gram-positive cocci, and had only discrete activity against the Bacteroides fragilis group. In general, temocillin displayed the same spectrum of activity against Enterobacteriaceae as third generation cephalosporins, but with a substantially lower intrinsic activity.

Brucellosis and parenteral drug abuse

The Centers for Disease Control has used a medium similar to those in this study for testing TMP-SMZ against Haemophilus influenzae and a variety of nonfastidious bacteria (4, 5). In our study, we attempted to find a single suitable medium for all drug-organism combinations, but hemin (X factor) inhibited Streptococcus pneumoniae and NAD (V factor) inhibited Streptococcus pyogenes. These supplements also alkalinized the media, which lowered erythromycin MIC% as has occurred with gram-negative enteric bacilli (6). The horse serum was not necessary for all organisms but was included because it minimized the number of medium modifications necessary without affecting the activities of the drugs.