Clinicians continue to question the usefulness of microscopic examination of Gram-stained sputum specimens ("Gram staining") and sputum culture for diagnosis of pneumonia. We analyzed the sensitivity of these techniques in 105 patients with pneumococcal pneumonia proven by blood culture. Gram staining revealed gram-positive cocci in pairs and chains, and culture yielded pneumococci in only 31% and 44% of all cases, respectively. However, sputum specimens were never submitted for examination in 31 cases; in 16 others, the specimen was inadequate and a culture was not done. Excluding these cases, the sensitivities of Gram staining and culture were 57% and 79%, respectively. If patients receiving antibiotics for >24 h had been excluded, Gram staining would have suggested pneumococci in 63%, and culture results would have been positive in 86%. Sensitivity increased in inverse proportion to the duration of antibiotic therapy (P<.05). Microscopic examination of sputum samples before antibiotics were administered and performance of culture within 24 h of receipt of such treatment yielded the correct diagnosis in >80% of cases of pneumococcal pneumonia.

Previous studies of the antibiotic susceptibility of Streptococcus milleri group organisms have distinguished among species by using phenotypic techniques. Using 44 isolates that were speciated by 16S rRNA gene sequencing, we studied the MICs and minimum bactericidal concentrations of penicillin, ampicillin, ceftriaxone, and clindamycin for Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus. None of the organisms was resistant to beta-lactam antibiotics, although a few isolates were intermediately resistant; one strain of S. anginosus was tolerant to ampicillin, and another was tolerant to ceftriaxone. Six isolates were resistant to clindamycin, with representation from each of the three species. Relatively small differences in antibiotic susceptibilities among species of the S. milleri group show that speciation is unlikely to be important in selecting an antibiotic to treat infection caused by one of these isolates.Three species compose the Streptococcus milleri group: Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus (5,12,13). Investigators who have used phenotypically differentiated strains within the S. milleri group have suggested that these three species have similar antibiotic susceptibilities (1,4,7,8). Phenotypic identification to the species level, however, has been shown to be difficult and at times unreliable (3,6,9). In order to compare the antibiotic susceptibilities of species within the S. milleri group, we determined the MICs and minimum bactericidal concentrations (MBCs) of four clinically relevant antibiotics for 44 genotypically characterized strains of the S. milleri group. MATERIALS AND METHODSBacteria. Forty-four clinically significant isolates of the S. milleri group that had been isolated from different patients between 1985 and 2000 were studied. All had been implicated as the causative organisms in infection (2). Their sources of isolation are summarized in Table 1. These strains were assigned to the S. milleri group based on the results of API 20 Strep system (bioMérieux Vitek, Hazelton, Mo.) tests and were further speciated by PCR amplification and sequence analysis of a segment of the 16S rRNA gene (3). They were stored at Ϫ70°C after having been passaged no more than two or three times. In addition to two well-characterized strains of Streptococcus pneumoniae that have been studied repeatedly in our laboratory, the following American Type Culture Collection (ATCC) strains were included as reference strains: ATCC 27335 (S. intermedius), ATCC 9895 and ATCC 33397 (S. anginosus), and ATCC 29213 (Staphylococcus aureus).MIC and MBC testing. Todd-Hewitt broth (Difco, Detroit, Mich.) containing 0.5% yeast extract (Difco) (THY), a broth medium previously shown by our laboratory to be optimal for testing the MICs of S. pneumoniae (10), was used in this study. Preliminary studies showed that this medium supported the growth of S. milleri group isolates more reliably than Mueller-Hinton or tryptic soy broth. Penicillin G (Sigma...

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Few modern studies have enumerated the conditions associated with leukocytosis. Our clinical experience has implicated Clostridium difficile infection in a substantial proportion of patients with leukocytosis. In a prospective, observational study of 400 inpatients with WBC counts of >/=15,000 cells/mm(3), we documented >/=1 infection in 207 patients (53%). Of these 207 patients, 97 (47%) had pneumonia, 60 (29%) had urinary tract infection, 34 (16%) had soft-tissue infection, and 34 (16%) had C. difficile infection. C. difficile infection was present in 25% of patients with WBC counts of >30,000 cells/mm(3) who did not have hematological malignancy. Other causes of leukocytosis in the 400 patients included physiological stress, in 152 patients (38%); medications or drugs, in 42 (11%); hematological disease, in 22 (6%); and necrosis or inflammation, in 22 (6%). C. difficile infection is a prominent cause of leukocytosis and this diagnosis should be considered for patients with WBC counts of >/=15,000 cells/mm(3), even in the absence of diarrheal symptoms.

Because Streptococcus milleri group (SMG) bacteria--Streptococcus constellatus, Streptococcus intermedius, and Streptococcus anginosus--exhibit a striking propensity to cause abscesses, the interaction of these organisms with human polymorphonuclear leukocytes (PMNL) was examined. After incubation in pooled normal human serum, SMG stimulated less chemotaxis than did Staphylococcus aureus, in contrast to viridans streptococci, which caused greater chemotaxis than did S. aureus. PMNL ingested greater numbers of SMG and viridans streptococci than S. aureus but killed these organisms more slowly and less completely. Relative resistance to killing by PMNL is expected in organisms that cause abscesses, and inhibition of chemotaxis may contribute to pathogenicity, because delayed arrival of PMNL gives a head start to proliferating bacteria. This study helps explain the capacity of SMG to cause abscesses. It is unclear, however, why viridans streptococci, bacteria that rarely produce abscesses, share some of these same properties.