Virulence in Rats of Gentamicin-Carbenicillin-Resistant Pseudomonas

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Pseudomonas aeruginosa resistant to both gentamicin and carbenicillin was isolated with increasing frequency at the Cincinnati Veterans Administration Hospital during the period 1971 to 1974. A comparison of patients from whom P. aeruginosa was isolated during this period failed to reveal any significant clinical differences between the patients colonized or infected with resistant organisms and those colonized or infected with susceptible organisms. Overt clinical infection attributable to either organism was rare. The antibiotic-resistant organisms were isolated most frequently from urine. Isolation of the antibiotic-resistant organisms was more frequent from patients who had previously received gentamicin.

Section: Discussionsupporting

confidence: 78%

mentioning

confidence: 99%

Nosocomial Infection with Gentamicin-Carbenicillin-Resistant Pseudomonas aeruginosa

Baird

Slepack

Kauffman

et al. 1976

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“…Others have verified the greater incidence of Gr Klebsiella and Enterobacter infection when compared with Gr Pseudomonas (17). Although Gr Pseudomonas appears to cause less symptomatic infection than G' Klebsiella, Gr Pseudomonas is fully capable of causing serious disease, as shown in this study as well as others (1,13) and in an experimental rat model (19). The clinical characteristics of patients developing infection or colonization with Gr organisms were similar to those described by others; this possibly reflects the fact that several of the previous studies have come from institutions very similar to ours (13,17,20).…”

Section: Methodssupporting

confidence: 48%

Surveillance of Gentamicin-Resistant Gram-Negative Bacilli in a General Hospital

Kauffman

Ramundo

Williams

et al. 1978

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gentamicin and tobramycin resistance by standardized disk testing. For Pseudomonas isolates, gentamicin resistance was 17.1% and tobramycin resistance was 2.8%. For other gram-negative bacilli, gentamicin resistance was 5.5% and tobramycin resistance was 5.4%. Seventy-four patients from whom gentamicin-resistant organisms were isolated from 1 January to 30 June 1976 were studied prospectively. These patients were elderly, had serious underlying diseases, and had received prior antibiotic therapy. Eleven patients carried gentamicin-resistant organisms at the time of transfer to our hospital from community hospitals or nursing homes. Of the 82 isolates from these 74 patients, 52 were from the urine. Pseudomonas was found most frequently (32 isolates), followed by Klebsiella (15 isolates), Enterobacter (10 isolates), Serratia (10 isolates), and Proteus (9 isolates). Only 3 of 32 Pseudomonas isolates caused symptomatic infection, while 16 of 50 other gram-negative bacilli were responsible for symptomatic infection. Although amikacin was the most active drug against gentamicin-resistant gram-negative bacilli and had not been used in our hospital at the time of this study, 25% of Pseudomonas and 18% of all gram-negative bacilli showed resistance to this aminoglycoside.

“…Despite the high incidence of resistant pseudomonas in the urinary tracts of these patients, it appears that these strains are relatively low in virulence. Slepack et al have shown that RPLll has no antivirulent effects in a test system using rats (14). The clinical signif-VOL.…”

Section: Resultsmentioning

confidence: 99%

Resistance Plasmids of Pseudomonas aeruginosa: Change from Conjugative to Nonconjugative in a Hospital Population

Korfhagen

Ferrel

Menefee

et al. 1976

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Properties ofa population ofcarbenicillin-and gentamicin-resistant, tobramycin-susceptible Pseudomonas aeruginosa at Veteran's Administration Hospital, Cincinnati, Ohio, have been followed during a 16-month period. As originally described, the strains were isolated from patients with urinary tract colonizations and were predominantly Parke-Davis immunotype 7. For the majority of these organisms, antibiotic resistance was correlated with the presence of a selfconjugative plasmid of incompatibility group P-2. The source and relative incidence of multiply resistant isolates have remained constant during the current study, but the immunotype has shifted form type 7 to type 2. Concomitantly, the population has lost the property of conjugative transfer of resistance, and resistant strains are now compatible with P-2 plasmids. A group P-2 R plasmid, pMG5, will mobilize resistance markers, demonstrating that the multiple resistance of the nonconjugative strains is mediated by R plasmids. Additionally, gentamicin resistance due to either conjugative or nonconjugative plasmids is correlated with the presence of similar gentamicin acetyltransferase activity. pMG5-mobilized plasmids are shown to be incompatible with pMG5. pMG5 is also shown to mobilize resistance markers from nontransferring antibioticresistant strains representing populations from Parkland Memorial Hospital, Dallas, Texas, and Cleveland Clinic Foundation, Cleveland, Ohio.