Identification of multiple clones of extended-spectrum cephalosporin-resistant Streptococcus pneumoniae isolates in the United States

We characterized 12 isolates of Streptococcus pneumoniae with various levels of susceptibility of penicillin and extended-spectrum cephalosporins by antimicrobial susceptibility patterns, serotypes, ribotypes, chromosomal DNA restriction patterns by pulsed-field gel electrophoresis, multilocus enzyme electrophoresis patterns, penicillin-binding protein (PBP) profiles, and DNA restriction endonuclease cleavage profiles of pbp1a, pbp2x, and pbp2b. Seven cefotaxime-resistant (MIC, > or = 2 micrograms/ml) serotype 23F isolates were related on the basis of ribotyping, pulsed-field gel electrophoresis, and multilocus enzyme electrophoresis, but they had two slightly different PBP patterns: one unique to strains for which the MIC of penicillin is high (4.0 micrograms/ml) and one unique to strains for which the MIC of penicillin is low (0.12 to 1.0 micrograms/ml). The pbp1a and pbp2x fingerprints were identical for the seven isolates; however, the pbp2b fingerprints were different. An eighth serotype 23F isolate with high-level resistance to cephalosporins was not related to the other seven isolates by typing data but was a variant of the widespread, multiresistant serotype 23F Spanish clone. The PBP profiles and fingerprints of pbp1a, pbp2x, and pbp2b were identical to those of the Spanish clone isolate. An additional serotype 6B isolate with high-level resistance to cephalosporins had unique typing profiles and was unrelated to the serotype 23F cephalosporin-resistant isolates but was related on the basis of genetic typing methods to a second serotype 6B isolate that was cephalosporin susceptible. The serotype 6B isolates had different PBP profiles and fingerprints for pbp1a, but the fingerprints for pbp2x and pbp2b were the same.     

Genotypic and phenotypic analysis of Salmonella strains associated with an outbreak of equine neonatal salmonellosis

Isolates of Salmonella choleraesuis serotype ohio (S. ohio) recovered during an outbreak of equine neonatal salmonellosis on a Thoroughbred farm were compared with isolates of the same serotype from various animal, feed and environmental sources. Biochemical profiles, antimicrobial susceptibility patterns, phage susceptibility, plasmid profiles, restriction endonuclease analysis and ribotyping were used to compare relatedness of the strains. A total of 46 outbreak and non-outbreak associated isolates of S. ohio were studied. Differences in antimicrobial susceptibility patterns, phage susceptibility and plasmid profiles were useful for differentiating outbreak isolates from other equine isolates as well as bovine, porcine and some poultry isolates. Feed and other poultry isolates, most in geographic proximity to the outbreak, were indistinguishable from outbreak isolates by any of the methods employed. Investigative studies on the farm along with results of genotypic and phenotypic analysis of isolates suggested that contaminated feed was the most likely source of Salmonella in this outbreak.     

"Sniffin'' sticks": screening of olfactory performance

OBJECTIVE: To study the loss of antimicrobial susceptibility in repeat (same patient, same bacterial species, and same site) aerobic gram-negative bacilli (AGNB) isolated from individual patients during their stay in the intensive-care unit (ICU). SETTING: A 792-bed, tertiary-care community hospital with a total of 107 adult, pediatric, and neonatal ICU beds. METHOD: An observational prospective study performed November 1992 through mid-July 1993. RESULTS: Of 594 consecutive AGNB from 287 ICU patients, 117 isolates (20%) from 55 patients (19%) were repeat isolates, with the majority obtained from respiratory secretions (83%). Pseudomonas aeruginosa and Enterobacter species accounted for 61% of the isolates. Forty-two (36%) of the repeat isolates from 24 patients (44%) had > or = 4-fold increase in minimum inhibitory concentration to at least one antibiotic and no longer were considered fully susceptible based on National Committee on Clinical Laboratory Standards criteria. Loss of antimicrobial susceptibility often developed within several (median 8) days and was associated only infrequently with simultaneous transition from colonization to infection in the individual patient. Use of certain beta-lactam antibiotics was associated with increasing resistance to several other antibiotics in the same class. Concurrent use of beta-lactams and aminoglycosides did not prevent loss of antimicrobial susceptibility to the former in repeat isolates. CONCLUSION: We conclude that loss of antimicrobial susceptibility in repeat AGNB isolated from ICU patients is common, usually is not associated with transition from colonization to infection, and often is associated with prior use of antibiotics. Minimizing antibiotic use in ICU patients should help reduce the risk of antimicrobial resistance in repeat AGNB isolates.     

Evaluation of a UDP-glucose-4-epimeraseless mutant of Salmonella typhi as a liver oral vaccine

A mutant (Ty21a) of Salmonella typhi, which lacks the enzyme uridine 5'-diphosphate-glucose-4-epimerase, was evaluated in volunteers for use as a live attenuated oral typhoid vaccine. Five to eight doses of vaccine (containing 3-10(10) viable organisms per dose) were given to 155 men without significant side effects. The rate of excretion of the vaccine strain in stools was low, and the majority of isolations occurred on day 1 after vaccination. Revertants able to fement galactose were not found in any of 958 stool isolates tested. The mutant, strain Ty21a, grown in brain-heart infusion broth (BHIB) with 0.1% galactose, produces more O side chain than the same vaccine strain cultivated without galactose. Volunteers vaccinated with strain Ty21a grown in galactose and then challenged with 10(5) virulen S. typhi were significantly protected from disease and also had decreased stool carriage of S. typhi as compared with controls. Strain Ty21a grown without galactose did not provide vaccinees significant protection nor decrease fecal excretion of S. typhi as compared with controls. Strain Ty21a, when grown in BHIB with 0.1% galactose, results in a safe, stable and protective oral vaccine that warrants further study in field trials.     

Shigellae isolated in 1997--plasmid profiles and antibiotic resistance

INTRODUCTION: Shigella spp is one of the most frequently isolated bacteria causing acute diarrhea with us. Genetics of pathogenicity of Shigella spp. includes chromosomal and plasmid genes. Most virulence factors are coded by invasion plasmid antigen genes residing on a 180-230 MDa plasmid. There is a big problem with multiple resistance of Shigella spp. strains, which is mostly plasmid-borne. Genetic analysis of bacterial cells, that is plasmid profile analysis, is important for investigation of sources and ways of spreading of the infection. All isolates originating from the same clone have identical plasmid profiles, i.e. number and size of plasmids. The aim of the investigation was: comparing the type of resistance to antimicrobical agents found in epidemic and nonepidemic. Shigella strains isolated in 1997, analyzing plasmid profiles of these isolates and confirming their epidemic connection. MATERIAL AND METHODS: Susceptibility to antibiotics was examined by a standard disc-diffusion method. Plasmid profiles of 40 strains (20 from the outbreak and 20 from sporadic cases) were tested using a method of alkaline lysis by Birnboim and Doly followed by electrophoresis in agarose gel. RESULTS: Shigella strains were resistant to antimicrobial agents which are most commonly used. Epidemic isolates shared the same resistance type, they were resistant to cephalexin, streptomycin and co-trimoxazole. The dominant type of resistance of nonepidemic strains was to ampicillin, streptomycin and co-trimoxazole. Strains isolated during the outbreak had identical plasmid profiles (2 plasmid bands of 55 and 1.5 MDa). Non-epidemic isolates had different plasmid profiles as well as type of resistance. CONCLUSION: Strains of Shigella spp. isolated during an outbreak had the same type of resistance and the same plasmid profiles, which indicated their origin from the same clone. The plasmid profile analysis is a reliable and precise method for determination of epidemic connection of Shigella isolates.     

Plasmid profiles and antimicrobial susceptibility of Campylobacter jejuni isolated from Israeli children with diarrhea

Thirty Campylobacter jejuni (C. jejuni) strains isolated from stools of Israeli children with enteritis were tested for sensitivity to eight antimicrobial agents (MIC) and the presence of plasmids. It was found that all the isolates were sensitive to ciprofloxacin, ofloxacin, furazolidone and erythromycin. Of the 30 strains tested, 21 (70%) were found to be tetracycline-resistant, a relatively high resistance rate as compared with data from other countries and previous reports from Israel. Plasmids were detected in 17 out of 30 C. jejuni isolates (55.6%). A total of nine different plasmid profiles could be distinguished; six profiles were represented by one strain each. Of the 21 tetracycline-resistant strains, plasmids were found in 17 isolates (80%) carrying from 1-2 to 5 plasmids of various sizes. No plasmids were found in tetracycline-sensitive strains, with the exception of one isolate which contained a 24.4 MDa plasmid and was co-trimoxazole-resistant. Our studies indicate a relatively high percentage of tetracycline-resistant C. jejuni isolates in the Tel Aviv area. In 80% of these strains, various plasmid profiles were detected.     

Finger lengthening by the modified Gillies method

Strains of Aeromonas hydrophila isolates from skin lesions of the common freshwater fish, Telapia mossambica, were screened for the presence of plasmid DNA by agarose gel electrophoresis and tested for susceptibility to 10 antimicrobial agents. Of the 21 fish isolates examined, all were resistant to ampicillin and sensitive to gentamycin. Most isolates were resistant to streptomycin (57%), tetracycline (48%) and erythromycin (43%). While seven of 21 isolates harboured plasmids, with sizes ranging from 3 to 63.4 kilobase pair (kb), it was only possible to associate the presence of a plasmid with antibiotic resistance (ampicillin and tetracycline) in strain AH11. Both the plasmid and the associated antimicrobial resistance could be transferred to an Escherichia coli recipient by single-step conjugation at a frequency of 4.3 x 10(-3) transconjugants per donor cell.     

Epidemiological study of an outbreak due to multidrug-resistant Enterobacter aerogenes in a medical intensive care unit

In 1993, 63 isolates of Enterobacter aerogenes were collected from 41 patients in a medical intensive care unit (ICU). During the same period, only 46 isolates from 32 patients were collected in the rest of the hospital. All isolates were analyzed by antibiotic resistance phenotype, and 77 representative isolates were differentiated by plasmid restriction analysis, ribotyping, and arbitrarily primed (AP)-PCR. The extended-spectrum beta-lactamases produced by 22 strains were characterized by determination of their isoelectric points and by hybridization of plasmid DNA with specific probes. The isolates were divided into 25 antibiotic resistance phenotypes, either susceptible (group I) or resistant (group II) to aminoglycosides, and exhibited three phenotypes of resistance to beta-lactams: chromosomally derepressed cephalosporinase alone or associated with either extended-spectrum beta-lactamases (mainly of the SHV-4 type) or imipenem resistance. The results of the tests divided the 77 representative isolates (group I, n = 21; group II, n = 56) into 15 plasmid profiles, 14 ribotypes, and 15 AP-PCR patterns. Although the resistant isolates (group II) exhibited different plasmid profiles, ribotyping and AP-PCR analysis demonstrated an identical chromosomal pattern, indicating an epidemiological relatedness. They were mainly found in the medical ICU and occasionally in other units. The susceptible strains (group I) had various and distinct markers and were mainly isolated in units other than the medical ICU. In conclusion, the presence of a nosocomial outbreak in an ICU and the spread of a multidrug-resistant epidemic strain throughout the hospital was confirmed. Ribotyping and AP-PCR represent discriminatory tools for the investigation of nosocomial outbreaks caused by E. aerogenes.     

Acute opioid dependence in the cardiovascular system of the spinal rat

A cluster of infections caused by Enterobacter cloacae was observed among preterm neonates in a neonatal intensive care unit (NICU) of a pediatric hospital in Osnabrück, Germany. The presence of similar antimicrobial susceptibility patterns among the bacterial isolates prompted an investigation to determine whether a limited spread of a single strain existed. All 12 E. cloacae isolates from the NICU and 50 nonrelated strains were fingerprinted by small-fragment restriction endonuclease analysis (SF-REA) of EcoRI DNA digests. Selected isolates were further characterized by pulsed-field gel electrophoresis (PFGE) of NotI- or XbaI-generated genomic restriction fragments. Epidemiologically unrelated strains were clearly discriminated by both methods. Results achieved by SF-REA and PFGE revealed that of the 12 isolates from the NICU, 11 belonged to the same genotypic cluster. Since all reagents and equipment for both techniques are commercially available, DNA fingerprinting by SF-REA or PFGE is proposed as a useful tool in the microbiology laboratory for investigating the epidemiological relatedness of E. cloacae strains of clinical and environmental origin.     

Persistence of Staphylococcus aureus strains among cystic fibrosis patients over extended periods of time

Pulsed-field gel electrophoresis (PFGE) of SmaI macrorestriction fragments of chromosomal DNA was used to confirm the persistence of methicillin-sensitive Staphylococcus aureus isolates in the sputum of 25 cystic fibrosis patients in five French hospitals. Three-to-eight consecutive isolates, with the same esterase electrophoretic type isolated from each patient over a period of 12-28 months, were analysed. Consecutive isolates with indistinguishable PFGE profiles were found in 12 patients (48%) and consecutive isolates with similar PFGE profiles showing minor differences of one-to-four fragments (similarity coefficient >/=84%) were found in 11 patients. Consecutive isolates with different PFGE profiles were obtained from only two patients, but the profiles found in each patient were more closely related to each other than to other profiles. The results were in agreement with esterase electrophoretic typing for 23 patients, and we considered that those patients were infected with a single persistent strain. For any given patient, variations in antibiotypes and phage types of consecutive isolates were not associated with major genotypic variations. PFGE is useful in confirming the persistence of S. aureus strains in cystic fibrosis patients over long periods.     

Molecular characterization of Vibrio cholerae O1 strains isolated during cholera outbreaks in Guinea-Bissau

In the present study, 19 strains of Vibrio cholerae O1 biotype El Tor isolated during outbreaks of cholera in Guinea-Bissau in 1987, 1994, and 1995 were characterized to investigate a possible epidemiological relationship among the isolates. On the basis of ribotyping with the restriction enzyme BglI, 5 strains isolated in 1987 showed two closely related ribotypes, while 14 strains isolated in 1994 and 1995 showed the same ribotype that was distinct from the ribotypes of strains isolated in 1987. Southern blot hybridization of BglI-digested genomic DNA with a cholera toxin probe demonstrated that the strains isolated in 1987 showed an identical cholera toxin genotype, whereas O1 strains isolated in 1994 and 1995 showed the same genotype that was distinct from the genotype of strains isolated in 1987. These results were supported by the results of antibiotic susceptibility testing, in which strains isolated in 1987 showed resistance to polymyxin B only, while each of the strains from 1994 and 1995 showed resistance to polymyxin B, trimethoprim-sulfamethoxazole, and the vibriostatic agent O/129. Although our results are based on a limited number of V. cholerae O1 strains, they suggest that the epidemic in Guinea-Bissau in 1994 and 1995 was due to the introduction of a new strain to the country.     

Analysis of an outbreak of non-phage-typeable methicillin-resistant Staphylococcus aureus by using a randomly amplified polymorphic DNA assay

A cluster of methicillin-resistant Staphylococcus aureus (MRSA) infections among patients on an intensive care unit (ICU) was detected by routine infection control surveillance. In the period from 5 January to 22 June 1995, 10 patients on the ICU and a further 6 patients (5 on one ward that had received colonized patients transferred from the ICU) were affected by MRSA strains with the same antibiotic susceptibility patterns. Seven (44%) of these 16 colonized patients developed MRSA bacteremia. MRSA isolates with the same characteristics were also found on the hands of one member of the ICU staff. The isolates were untypeable by phage typing, but 15 of 17 outbreak strains analyzed genetically had identical randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) profiles. A single strain of MRSA that was nontypeable by phage typing and that was isolated on the ICU on 1 January and six nontypeable and epidemiologically unrelated MRSA isolates all had RAPD profiles distinct from that of the outbreak strain. Implementation of strict infection control measures stopped the further spread of MRSA on the ICU, the affected general ward, and seven other wards that received MRSA carriers from the ICU. Although nontypeable by phage typing and not previously recognized as an epidemic strain, this strain of MRSA was readily transmissible and highly virulent. RAPD typing was found to be a simple, rapid, and effective method for the epidemiological investigation of this outbreak, and performance of typing by this method was simpler and less time-consuming than that of typing by PFGE. RAPD typing may have more general application for the study of S. aureus infections in hospitals.     

Molecular analysis of bovine spongiform encephalopathy and scrapie strain variation

Five mouse scrapie strains, a mouse-passaged scrapie isolate derived from a field case in sheep in Germany, and 2 mouse-passaged bovine spongiform encephalopathy (BSE) isolates were analyzed by immunoblot in regards to banding patterns of proteinase K-digested pathologic prion proteins (PrPres). To obtain reliable results, the photo-imager technique was used for measurement of staining band intensities. Distinct and reproducible profiles were observed for the different strains or isolates. A British and a German BSE isolate were similar, suggesting the same source of infection. The German scrapie isolate resembled scrapie strain ME7, which has frequently been isolated from sheep scrapie in the past. In selected strains or isolates, no influence of the mouse lines used was observed on PrPres profiles, nor were brain region-specific differences apparent. This investigation suggests that PrPres glycotyping can be an invaluable tool for the in vitro differentiation of BSE and scrapie isolates.     

Molecular typing of Klebsiella pneumoniae isolates from a neonatal intensive care unit

The epidemiological features of 60 multiresistant K. pneumoniae strains isolated from 1991 to 1995 in a neonatal ward are described. Antibiotic. Susceptibility testing and plasmid profile analysis were used as subtyping procedures. Antibiotic susceptibility typing was not informative enough since discrimination among isolates was typically poor. Plasmid profile analysis demonstrated that 58 out of 60 strains harboured one or more plasmid DNA bands, of different molecular weights ranging between 1.8 and 150 Mda. Small plasmids were best visualized after the alkaline lysis procedure, while large plasmids by the Kado and Liu method. A combination of plasmid patterns obtained by the two extraction procedures was used to define the final plasmid profile for each strain. Thirteen different plasmid profiles were identified among the collection of K. pneumoniae isolates from newborn patients of the same intensive care unit. The investigation showed that the strains were not responsible for a single outbreak.     

Evidence of nosocomial infection in Japan caused by high-level gentamicin-resistant Enterococcus faecalis and identification of the pheromone-responsive conjugative plasmid encoding gentamicin resistance

A total of 1,799 Enterococcus faecalis isolates were isolated from inpatients of Gunma University Hospital, Gunma, Japan, between 1992 and 1996. Four hundred thirty-two (22.3%) of the 1,799 isolates had high-level gentamicin resistance. Eighty-one of the 432 isolates were classified and were placed into four groups (group A through group D) with respect to the EcoRI restriction endonuclease profiles of the plasmid DNAs isolated from these strains. The 81 isolates were isolated from 36 patients. For 35 of the 36 patients, the same gentamicin-resistant isolates were isolated from the same or different specimens isolated from the same patient at different times during the hospitalization. For one other patient, two different groups of the isolates were isolated from the same specimen. Groups A, B, C, and D were isolated from 5, 14, 12, and 6 patients, respectively. The strains had multiple-drug resistance. The restriction endonuclease digestion patterns of the E. faecalis chromosomal DNAs isolated from isolates in the same group were also identical. The patients who had been infected with the gentamicin-resistant isolates from each group were geographically clustered on a ward(s). These results suggest that the isolates in each group were derived from a common source and had spread in the ward. The gentamicin-resistant isolates exhibited a clumping response upon exposure to pheromone (E. faecalis FA2-2 culture filtrate). The gentamicin resistance transferred at a high frequency to the recipient E. faecalis isolates by broth mating, and the pheromone-responsive plasmids encoding the gentamicin resistance were identified in these isolates.     

Variation in electrophoretic karyotype and antifungal susceptibility of clinical isolates of Cryptococcus neoformans at a university-affiliated teaching hospital from 1987 to 1994

Ninety-eight isolates of Cryptococcus neoformans were collected from 30 patients at the University of Iowa Hospitals and Clinics from December 1987 through December 1994. The susceptibility of each isolate was determined against fluconazole, itraconazole, amphotericin B, and flucytosine. Of the 98 isolates, 53 were recovered from blood, 19 were recovered from cerebrospinal fluid (CSF), and 26 were recovered from other sources. Although the strains were isolated from the same institution, DNA typing by electrophoretic karyotype (EK) revealed wide genetic variation. Overall, 23 different EK profiles were identified by computer-aided analysis. An isolate exhibiting a single EK was isolated from 24 of 30 patients (80%), whereas multiple strains with unique EKs were isolated from 6 of 30 (20%) patients. Of the six patients who had multiple strains recovered, only one individual had two strains isolated from unique body sites, one strain from the blood and the other from the CSF. Six strains were isolated from multiple patients. Nine patients had multiple sequential isolates recovered over periods of time ranging from 3 days to 4 months. EK analysis revealed persistence of the same genotype in six of the cases. Three patients, however, appeared to have an isolate with a second distinct EK emerge during therapy. Of the patients with sequential positive cultures, an increase in the MICs for test agents was observed in only one case. C. neoformans isolates were collected over a period of 7 years, during which time MICs at our institution remained stable.     

Mortality in geriatric psychiatric inpatients

OBJECTIVE: To report current information about invasive pneumococcal infections, capsular types and antimicrobial resistance in Canada. DESIGN: Retrospective analysis. SETTING: Canada. PATIENTS: A total of 976 patients from whom Streptococcus pneumoniae was isolated from blood or cerebrospinal fluid between Jan. 1, 1992, and Dec. 31, 1995. OUTCOME MEASURES: Capsular type and antimicrobial susceptibility. RESULTS: Twenty types accounted for 90.8% of the isolates from patients over 5 years of age; all but type 15A are covered by the currently available 23-valent vaccine. Nine types accounted for 92% of the isolates recovered from children 5 years and less. Reduced susceptibility to penicillin was found in 7.8% of the collection and was associated with types 6B, 9V and 19A. Full resistance to penicillin was observed most frequently during 1995 and was associated with type 9V. Rates of reduced susceptibility over one 12-month period were 19.5% for trimethoprim-sulfamethoxazole and 4.5% or less for each of cefotaxime, ceftriaxone, chloramphenicol, erythromycin, ofloxacin and tetracycline. CONCLUSIONS: Over 90% of invasive pneumococcal infections are covered by the currently available vaccines (for people over 2 years of age) and the pneumococcal protein-polysaccharide conjugate vaccines under development for young children. The high frequency of antimicrobial resistance observed requires more complete investigation and confirmation; however, taken from a global perspective, it supports the need to develop better control strategies, including greater use of new and existing vaccines.     

Spindle-cell thymic carcinoid occurring in multiple endocrine neoplasia I: fine-needle aspiration findings in a case

The biological properties and susceptibility to antimicrobial agents of Bacillus larvae were examined. Twenty-nine strains, 28 isolates from each outbreak of American foulbrood in Japan and a B. larvae type strain (ATCC 9545T) were used. our B. larvae isolates had almost the same biological properties as the type strain. The isolates were more susceptible to penicillins, macrolides and lincomycin, a lincosamide, than other antimicrobials. Microsamicin among the macrolides and ampicillin among the penicillins appeared to be the most effective agents.     

Application of a diagnostic DNA probe for the differentiation of the two types of Mycoplasma mycoides subspecies mycoides

Contagious bovine pleuropneumonia (CBPP), which is caused by Mycoplasma mycoides subspecies mycoides, is still a serious disease in some parts of the world. There is also a commonly occurring mycoplasma which is sufficiently related to the CBPP organism to bear the same name, even though this organism does not cause CBPP. Thus it is very important to be able to distinguish between these organisms and identify either with certainty. Fragments derived from M mycoides subspecies capri by restriction enzyme digestion of genomic DNA were cloned into the vector M13mp8. One resulting clone CAP-21, with a 1.5 kb insert was used as a probe in Southern hybridisation assays where genomic DNA was digested with the restriction endonuclease TaqI. This probe could differentiate a strain of M mycoides subspecies mycoides which does not cause CBPP. Subsequent tests on 14 other strains from cattle and goats showed that although they were isolated from diverse geographical areas, CAP-21 could clearly differentiate between these two types of M mycoides subspecies mycoides.     

Aspects of epidemiology of Campylobacter in poultry

The CPS ID 2 (CPS) chromogenic agar was compared to routine media for use in the isolation, enumeration, identification, and susceptibility testing of bacteria recovered from urine specimens. Of 487 urine specimens, 318 were culture negative, 12 were positive on CPS only, 16 positive on routine only, and 141 positive on both. The enumeration of microorganisms agreed for 96 of the 141 cultures. Fewer organisms were recovered on CPS for 25 cultures, more for 20 cultures. The identification of bacteria from CPS and routine media agreed for all isolates. Susceptibility testing was performed for 100 isolates. The categorical susceptibility test results from isolates grown on CPS agreed with results from routine media for 77 isolates. For the remaining 23 isolates, one or more discrepancies were seen involving 16 different antimicrobial agents; 27 minor, 1 major, and 6 very major errors. After additional testing, there were 10 confirmed errors, 7 minor and 3 very major errors. This study demonstrates that CPS agar is a reliable medium for culturing urine. Susceptibility testing directly from this medium resulted in low error rates for all antimicrobial agents tested.