We retrospectively studied 24 adults with bacteremic pneumonia (25 episodes) due to penicillin-resistant pneumococci, for which the minimal inhibitory concentrations (MICs) of penicillin G were 0.12 to 8.0 micrograms per milliliter; 79 percent of the strains showed multiple antibiotic resistance. As compared with 48 control patients with bacteremic pneumonia caused by penicillin-sensitive pneumococci, the 24 patients with penicillin-resistant pneumococci had a significantly higher incidence of use of beta-lactam antibiotics during the previous three months (65 vs. 17 percent, P = 0.0008), hospitalization during the previous three months (58 vs. 21 percent, P = 0.0038), nosocomial pneumonia (37 vs. 6 percent, P = 0.0032), episodes of pneumonia during the previous year (29 vs. 4 percent, P = 0.010), and factors on initial presentation that were associated with a poor prognosis (an initially critical condition) (67 vs. 27 percent, P = 0.0030). Their overall mortality rate was significantly higher (54 vs. 25 percent, P = 0.0298). Eleven of 19 episodes of pneumonia due to organisms for which MICs were 0.12 to 2.0 micrograms per milliliter, which were treated with penicillin G (10 episodes) or another beta-lactam agent (9 episodes), resulted in recovery (2 of 10 patients in an initially critical condition recovered, as compared with all of 9 not initially in a critical condition, P = 0.0012). Two patients who had penicillin-resistant pneumococci for which MICs were 4.0 and 8.0 micrograms per milliliter did not respond to ampicillin and ticarcillin therapy, respectively. Our study suggests that pneumonia due to penicillin-resistant pneumococci may occur more often in a population with some identifiable risk factors, and may respond to intravenous high-dose penicillin therapy if MICs are less than or equal to 2 micrograms per milliliter. Cases involving higher resistance may require an alternative antibiotic.

The results of classic serological tests were compared with those of enzyme-linked immunosorbent assay in studies of immunoglobulins to Brucella in 761 serum samples from 75 patients with brucellosis. Except for five instances involving the IgM ELISA, all serological tests gave positive results at admission. Among the 63 patients without relapse, rates of persistent ELISA positivity (determined by the Kaplan-Meier method) 12 months after therapy were 25% for IgM, 69% for IgA, and 89% for IgG. Among the 12 patients with relapse, a second peak of ELISA IgG and IgA was often detected. The persistence of high serum antibody titers in patients without relapse was due mainly to IgG and was often associated with high titers at admission or with the presence of focal disease. Overall, serological changes were better detected by ELISA than by classic serological tests. While a second peak of ELISA IgG and IgA is a good marker of relapse, the persistence of high titers of IgG by itself is not a good predictor of chronic infection.

An outbreak due to extended-spectrum β-lactamase-producingKlebsiella pneumoniae (ESBL-KP) was detected from May 1993 to June 1995. A total of 145 patients, particularly patients in intensive care units (ICUs) (107 patients [72%]), were colonized or infected. Infection developed in 92 (63%) patients, and primary bacteremia caused by ESBL-KP was the most frequent infection (40 of 92 patients [43%]). A single clone of ESBL-KP was identified by pulsed-field gel electrophoresis analysis throughout the whole period, and no molecular epidemiological relationship could be found between the epidemic strain and non-ESBL-KP isolates. To determine risk factors for ESBL-KP infection weekly rectal swabs were obtained in three serial incidence surveys (470 patients); the probabilities of carriage of ESBL-KP in the digestive tract were 33% (October and November 1993), 40% (May and June 1994), and 0% (October and November 1995) at 10 days of ICU admission. A logistic regression model identified prior carriage of ESBL-KP in the digestive tract (odds ratio, 3.4; 95% confidence interval 1.1 to 10.4) as an independent variable associated with ESBL-KP infection. A statistically significant correlation was observed between the restricted use of oxyimino-β-lactams (189 defined daily doses [DDD]/1,000 patient-days to 24 DDD/1,000 patient-days) and the trends of ESBL-KP infection (r = 0.7; P = 0.03).