Clinical, epidemiologic and bacteriologic observations of an outbreak of methicillin-resistant Staphylococcus aureus at a large community hospital.

Over a 12 month period, 61 isolates of methicillin-resistant Staphylococcus aureus (MR-SA) were obtained in 23 hospitalized patients. Eight-six per cent of the patients were over 50 years of age, and 91 per cent were in the postoperative period. In 10 patients (42 per cent), MR-SA was the major pathogen, producing either pneumonia, empyema, osteomyelitis, lung abscess, enterocolitis, wound infection or bacteremia with sepsis. Three patients in this group died despite therapy with antibiotics with in vitro activity against these organisms. All the patients probably acquired their MR-SA in the hospital, and five carriers of the organism were identified among hospital personnel. This outbreak demonstrates the ability of MR-SA not only to colonize many patients in a relatively brief period of time, but also to produce serious disease.

Evaluation of the variety of plasmid profiles in S epidermidis isolates from hospital patients and staff.

Plasmid profiling was used to determine the variability of normal flora isolates of Staphylococcus epidermidis in order to evaluate the usefulness of plasmid profiling for identifying pathogens. Fifteen hospital staff members and patients repeatedly had cultures taken from the hands and nares, and multiple isolates were examined for plasmid profiles. S epidermidis isolated from the nares of 15 neonates were also examined. The total number of isolates examined for plasmid profiles was 726. Repetition of profiles was common among the different isolates from a single sampling (one swab). The frequency of re-isolating similar profiles on different days varied from 7% to 13%. Simultaneous isolation of similar profiles from nares and hands on the same individual varied from 0% to 11%, the percentage being lower for personnel. Isolation of the same plasmid profile from different individuals occurred only twice and resulted in an assignment probability of Pa = 0.002 for isolates obtained from different individuals. Significantly more isolates from nares contained plasmids (97%) compared with isolates from hands (89%). Patients who had two or more isolates of coagulase-negative staphylococci with similar profiles were judged, clinically, to have infections in 12 of 13 cases. However, the likelihood of re-isolating an S epidermidis strain with a similar plasmid profile twice from the same person at different times was sufficiently high to prevent plasmid profiling from being used as an absolute criterion for infection.

Cerebral blastomycosis: an immunodiagnostic study.

Cerebral blastomycosis may simulate a brain tumor. Its diagnosis is sometimes very difficult. The morphologic identification of the fungus may be misleading because it shares some common features with many other dimorphic fungi. Culturing and conversion of the organism from mycelial phase to yeast phase are not always successful. Immunofluorescent staining of the biopsy tissue is useful in confirming the diagnosis. However, a combination of double immunodiffusion (DID) test and complement fixation (CF) test makes the diagnosis more accurate and reliable. The direct role of macrophages in defending the host against blastomycosis is illustrated by electron microscopy.

Use of the leukocyte esterase and nitrite tests to determine the need for culturing urine specimens from a pediatric and adolescent population.

Using a commercially available dip stick 601 urine specimens were screened for leukocytes and bacteria by testing for the presence of leukocyte esterase and nitrite. The screening method was found to have a sensitivity of 88.7% and a predictive value of negative results of 98.5%.

In-use testing of four glutaraldehyde disinfectants in the Cidematic washer.

Four glutaraldehyde disinfectants (Cidex, Glutarex, Sonacide, and Sporicidin) were tested in routine use in the Cidematic washer to identify the most economic, effective disinfectant among them. An in vitro killing test with Pseudomonas aeruginosa (10-min exposure) and Mycobacterium smegmatis (20-min exposure) was used. All four disinfectants were effective prior to first use. In the use tests, Cidex killed both organisms for its claimed effectiveness period of 2 weeks. Glutarex was effective against Pseudomonas for its claimed effectiveness period of 4 weeks but was effective against Mycobacterium only 3 weeks. Sonacide, claimed to be effective for 4 weeks, killed Pseudomonas for 2 weeks but was ineffective against Mycobacterium after 1 week. Sporicidin (1:15 dilution), claimed to be effective for 30 days, did not kill either test organism after 5 days. Glutarex used for a 3-week period was found to be the most economic, effective substitute for Cidex in the Cidematic machine.

Species identification and susceptibility to 17 antibiotics of coagulase-negative staphylococci isolated from clinical specimens.

A total of 299 isolates of gram-positive, catalase-positive, coagulase-negative cocci were isolated from a variety of specimens collected from patients at a large university hospital, and 281 (94%) were identified as staphylococci by established methods. Using the scheme of Kloos and Schleifer, we determined the species of the coagulase-negative staphylococci. Staphylococcus epidermidis was the cause of all bacteremias and the most commonly isolated species from bone, joint, and wound infections. Staphylococcus haemolyticus was the second most common isolate from wound infections, and Staphylococcus saprophyticus was the most commonly isolated species from urinary tract infections. Antibiograms to 17 antimicrobial agents were performed by a microdilution technique, and the results revealed that S. epidermidis was resistant to a water spectrum of antimicrobial agents than the other species of staphylococci were.

Significance of Staphylococcus epidermidis in the clinical laboratory.

Susceptibility to 11 antibiotics was determined for 63 cultures of Staphylococcus aureus and 63 cultures of Staphylococcus epidermidis obtained at random from the clinical laboratory. The incidence of resistance to nine of these antibiotics was greater for S. epidermidis than for S. aureus. Studies of the minimal inhibitory concentration of these cultures to clindamycin showed that 61 cultures of S. aureus were susceptible whereas only 46 cultures of S. epidermidis were susceptible to this antibiotic. Although cultures of S. aureus were more active in the production of seven virulence factors, some cultures of S. epidermidis produced virulence factors. By successive cultivation in increasing concentrations of clindamycin, resistant variants were obtained for 10 cultures of S. aureus and 3 cultures of S. epidermidis. The presence of subinhibitory concentrations of clindamycin inhibited the production of some virulence factors by the resistant variants. In view of the greater resistance of S. epidermidis to antibiotics and its ability to produce virulence factors, its isolation in the clinical laboratory should not be regarded lightly.

Atypical reactions of Escherichia coli on eosin methylene blue agar.

Evidence is presented that atypical reactions of Escherichia coli on eosin methylene blue agar are due to variations in pH in localized areas of the medium.

Bacteriophage types and O antigen groups of Escherichia coli from urine.

Urinary strains of Escherichia coli from seven geographical regions were typed serologically for O-specific antigens and with phages capable of lysing the majority of urinary isolated. The O antigen groups 4, 6, 75, 1, 50, 7, and 25 were the common ones found. Of the 454 cultures tested, 66.1% were phage typable and 65.2% were serotypable with the 48 antisera employed. Also, 71.6% of the cultures for which an O group could be determined were phage typable. Furthermore, of those seven O-antigen groups implicated in urinary tract infection, 80.2% exhibited a phage pattern. Various phage types were found within an O-antigen group, and, although one phage type associated a high percentage of the time with one O-antigen group, no correlation was observed between other O-antigen groups and phage types. Studies with bacteriuric patients by phage typing showed the presence of two strains of E. coli within an O-antigen group. Serogrouping and phage typing of fecal isolates of E. coli revealed the presence of some O-antigen groups and phage types also found as predominant types among urinary isolates. Phage typability correlated highly with hemolysis of human erythrocytes. Elevated temperatures of incubation and a chemical curing agent were used to enhance typability of cultures refractory to the typing phages. Phage typing, due to its rapidity, ease, and ability to distinguish strains of E. coli within an O-antigenic group, is suggested as a possible method by which a better insight into the epidemiology of urinary tract infections may be obtained.

Comparison of a rapid micromedia method to cystine trypticase agar (CTA) and fluorescent methods for the identification of pathogenic Neisseria.

A four-hour micromedia method which detects enzymes formed by bacteria for the degradion of carbohydrates was compared to the utilization of carbohydrates was compared to the utilization of carbohydrates in cystine tyrpticase agar (CTA) for the identification of Neisseria gonorrhoeae and Neisseria meningitidis. This rapid micromedia method (RMM) correlated 100% with the utilization of carbohydrates in CTA. Identification of N. gonorrhoeae by RMM was compared to the identification achieved by a commercially available coagglutination method and a fluorescent antibody (FA) technique. Of 144 isolates identified as N. gonorrhoeae by RMM, 122 (84.7%) were identified by coagglutination and 141 (97.9%) were identified by FA as N. gonorrhoeae. Five (13%) of 40 isolates identified as N. meningitidis by RMM were identified as N. gonorrhoeae by coagglutination while eleven (28%) were identified as N. gonorrhoeae by the FA technique. One (14%) and four (57%) of seven isolates identified as Neisseria species were identified as N. gonorrhoeae by coagglutination and the FA technique respectively. The rapid micromedia method was found to be a quick, sensitive, specific and economic way of identifying N. gonorrhoeae and N. meningitidis.

Methicillin-resistant Staphylococcus aureus: introduction and spread within a hospital.

In March 1978, a strain of methicillin-resistant Staphylococcus aureus was introduced from the community into a university hospital. Within 6 months of admission of the index case, methicillin-resistant S. aureus was isolated from 30 additional patients, 22 of whom were epidemiologically linked by a common phage type (6/47/54/75/83A) and roommate-to-roommate spread. Sixteen of 31 cases were infected, six with bacteremia. Patients with infections received cephalosporins more frequently before infection than did control subjects (p < 0.05). Patients acquiring methicillin-resistant S. aureus in the intensive care unit had a longer mean stay, had higher overall mortality, and received nafcillin and aminoglycosides more frequently than did cohorted control subjects. By mid-1979, methicillin-resistant S. aureus accounted for 38%, 31%, and 24% of all nosocomial S. aureus postoperative wound, pulmonary, and bloodstream infections, respectively. In hospitals with significant methicillin-resistant S. aureus isolation rates, initial empiric therapy of presumed S. aureus infection with vancomycin seems warranted.

Transmissible drug resistance of Escherichia coli and Salmonella from humans, animals, and their rural environments.

Isolates of Escherichia coli and Salmonella species obtained from humans, animals, and their rural environments were tested for their ability to transfer multiple drug resistance to competent recipients. In all, 125 (52.9%) of 242 isolates of E.coli transferred all or part of their resistance to E.coli CSH-2, and 103 (44.4%) of 232 isolates of E.coli transferred all or part of their resistance to Salmonella choleraesuis var. kuzendorf 214. The data suggest that the multiple drug resistance of E.coli transferred all or part of their resistance to Salmonella choleraesuis var kuzendorf 214. The data suggest that the multiple drug resistance of E. coli in the gut of humans who work with livestock may be due to the transfer of resistance determinants from animal strains to the resident flora of the human gut. Such transfer could occur during transient passage through the digestive tract. Multiple drug-resistant Salmonella were isolated from all sources. In all, 48 (80%) of 60 isolates of Salmonella transferred all or part of their resistance to E. coli CSH-2, and isolates of Salmonella transferred all or part of their resistance to E.coli CSH-2, and 42 (82.4%) of 51 isolates of Salmonella transferred all or part of their resistance to S. choleraesuis var, kuzendorf 214. Fifty-three (46.9%) of 113 antibiotic-sensitive isolates of E.coli possessed resistance transfer factor, and six (23.1%) of 26 isolates with resistance transfer factor mobilized resistance determinants in isolates unable to transfer drug resistance during conjugation experiments.

Serratia marcescens bacteremia from contaminated pressure transducers.

Primary Serratia marcescens bacteremia developed in 17 patients in an intensive care unit after exposure to pressure monitoring devices. A study showed that all of the transducer heads were contaminated with S marcescens, and prospective culturing of 110 pressure monitoring lines disclosed a 24% rate of contamination with the same organism. Hand contamination occurs at the time the equipment is initially assembled; in five of eight trials, transmission was shown experimentally to occur by direct inoculation of open ports. Routine disinfection of the transducer heads with glutaraldehyde not only effectively decontaminated all pressure monitoring lines in use, but also controlled the outbreak.

Contaminated breast milk: A source of Klebsiella bacteremia in a newborn intensive care unit.

Five patients in a newborn intensive care unit (NICU) developed primary bacteremia due to Klebsiella during a 12-day period, May 2 through June 2, 1979, after feeding for 24-96 hr with contaminated breast milk. All patients had been fed via nasoduodenal tube with milk obtained from a single donor. The donor milk collected via electric suction pump was positive by gram stain for gram-negative rods and by culture for Klebsiella pneumoniae. A culture of hand-expressed milk was negative for gram-negative rods. The breast-pump tubing and safety trap were grossly contaminated with K. pneumoniae. Institution of proper sterilization to the pump equipment controlled the outbreak. This outbreak is the first documentation of nosocomial bacteremia as a major infectious complication of feedings of premature infants with contaminated breast milk.