Gram-negative bacilli as nontransient flora on the hands of hospital personnel.

The possibility that gram-negative bacilli (GNB) are part of the nontransient flora on hands was examined by using a broth rinse technique to detect low titers of GNB after a hygienic hand wash with soap and water. A total of 100 nurses who had direct patient contact and 40 controls without patient contact had a similar rate of recovery of GNB (46 and 55%, respectively). GNB persisted on the hands of 10 nurses throughout five successive hand washes with soap and water. Hand cultures were obtained daily from 12 nurses before and after a work shift in a surgical intensive care unit. GNB were recovered from 57% of individuals before patient contact and from only 24% after the work shift. Nontransient GNB on the hands of hospital personnel are a potential reservoir for hospital strains, and patient contact is not an obvious source for the acquisition of nontransient GNB.

Microbiologic studies of coagulase-negative staphylococci isolated from patients with nosocomial bacteraemias.

We studied 50 strains of coagulase-negative staphylococci (CNS) isolated from 50 patients with hospital-acquired bacteraemia, identified by prospective surveillance at the University of Virginia Hospital between March 1981 and September 1982. Using the Staph-Ident System for speciation, we found that 37 strains (74%) were Staphylococcus epidermidis, 7 (14%) Staph. hominis, 3 (6%) Staph. haemolyticus and 3 (6%) Staph. warneri. 33 (66%) of the strains produced slime and a higher proportion of the Staph. epidermidis group (75%) than the non-epidermidis group (46%), did so. Minimal inhibitory concentrations (MIC) were determined by a microdilution technique with 20 different antibiotics. There was no difference in geometric mean MICs between slime producers and non-slime producers within either the epidermidis or non-epidermidis group. The most potent antibiotics against Staph. epidermidis (MIC90 mg l-1) were rifampin (0.05), netilmicin (0.05), amikacin (2.9), thienamycin (0.75), teichomycin (0.85), vancomycin (1.0) and nafcillin (0.39). On the other hand strains were resistant to tobramycin (15), moxalactam (50), fosfomycin (greater than 64), and clindamycin (greater than 64). Overall, eight (16%) of the CNS strains were resistant to methicillin, three of which were Staph. haemolyticus. The non-epidermidis strains were more resistant than the Staph. epidermidis strains to most beta-lactam antibiotics. Differences in antibiograms indicate that speciation of CNS may prove useful for clinical and epidemiologic purposes.

Alteration of normal gastric flora in critical care patients receiving antacid and cimetidine therapy.

One hundred fifty-three critical care patients with documented cimetidine and antacid use were prospectively studied with serial gastric pH determinations and semiquantitative gastric fluid cultures. This study documents the abnormal gastric colonization of patients with therapeutically altered gastric acidity by hospital acquired gram negative rods (GNR). Three hundred twenty-four gastric fluid cultures from 153 patients revealed 152 (47%) positive cultures for GNR, 78 (24%) sterile specimens, and 94 (29%) positive for mixed oropharyngeal flora. One hundred forty (59%) of the 236 cultures at a pH of 4 or greater were positive for GNR. In contrast, only 12 (14%) of the 88 cultures at a pH of less than 4 were positive for GNR (p less than .001). Forty-six (52%) of 88 cultures at a pH of less than 4 were sterile as compared to only 32 (14%) of 236 sterile cultures at a pH of 4 or greater (p less than .001). At low pH, cultures are predominantly sterile and at a pH of 4 or greater the flora dramatically changes to hospital acquired GNR. This artificially maintained reservoir of gram negative rods in the critically ill patient is a potential reservoir of organisms causing nosocomial bacteremia or pneumonia in this high risk population.

Comparative activity of seven extended-spectrum cephalosporins against gram-negative bacilli from blood cultures.

One hundred sequential Gram-negative rod isolates from patients with hospital-acquired bloodstream infections were tested against seven new cephalosporins. Duplicate broth microdilution tests indicated superior activity for ceftazidime with 97% of strains susceptible to 16 mg/l. Less in-vitro activity was demonstrated cefotaxime (91% susceptible to 16 mg/l, P = 0.07), latamoxef (moxalactam) (90%, P = 0.04), cefoperazone (90%, P = 0.04), ceftriaxone (87%, P = 0.008), cefmenoxime (80%, P = 0.0001), and ceftizoxime (79%, P less than 0.0001). With the exception of cefoperazone, the newer drugs had mean MICs of less than or equal to 0.6 mg/l against Enterobacteriaceae. Ceftazidime and cefoperazone had highest activities against Pseudomonas aeruginosa with MIC90S of 4 and 16 mg/l, respectively. A comparison of recently published data shows important geographic differences in MIC90 data for the new cephalosporins against specific species.

In vitro activities of teichomycin, fusidic acid, flucloxacillin, fosfomycin, and vancomycin against methicillin-resistant Staphylococcus aureus.

Flucloxacillin, fosfomycin, fusidic acid, teichomycin, and vancomycin were tested against 50 clinical isolates of methicillin-resistant Staphylococcus aureus by a broth macrodilution technique. Teichomycin had a narrow range of activity, similar to that of vancomycin (0.5 to 2.0 micrograms/ml). Fusidic acid had the lowest range of inhibitory activity, with 50 and 90% MICs of 0.19 and 0.35 micrograms/ml, respectively. Flucloxacillin and fosfomycin showed less activity, with MICs up to 32 micrograms/ml.

Cefsulodin sodium therapy in cystic fibrosis patients.

Cefsulodin sodium is a narrow-spectrum cephalosporin with marked in vitro activity against clinical isolates of Pseudomonas aeruginosa. We have studied the antibiotic in a clinical trial in 10 patients admitted to the Pediatric Ward of the University of Virginia Medical Center with cystic fibrosis and recurrent acute lower respiratory tract infections with P. aeruginosa isolated from their sputa. The patients received 500 to 1,500 mg of cefsulodin every 6 hours by intravenous infusion for 10 to 22 days. Mean peak drug levels in plasma after 500, 1,000, and 1,500 mg were 46, 71, and 90 micrograms/ml, respectively, and the mean minimal inhibitory concentration of all organisms was 7.5 micrograms/ml. Detectable levels of cefsulodin in sputa were found in approximately half of the random samples and ranged from 2 to 5 micrograms/ml. The clinical response was satisfactory in nine (90%) of the patients. One patient gained weight and had improved pulmonary function tests but showed no reduction in sputum production and no improvement in arterial blood gas values. In pulmonary function tests, four of five patients tested showed an average 43% increase in forced vital capacity after initiation of therapy and five of five had an average 51% increase in forced expired volume in 1 s. No adverse effects were observed.