Differences among Providencia species in their in vitro susceptibilities to five antibiotics

Abstract

Significant differences among the three Providencia species (P. alcalifaciens, P. stuartii, and P. rettgeri) in antimicrobial susceptibilities to five antibiotics were shown. P. stuartii was the most resistant of the three species, and P. alcalifaciens was the most susceptible. P. rettgeri was similar to P. stuartii in susceptibilities to cefoxitin, cephalothin, and cefamandole but differed in showing greater susceptibilities to tobramycin and gentamicin. Cefoxitin (16 jAg/ml) and cefamandole (16 yg/ml) inhibited a greater proportion of P. stuartii isolates than did cephalothin, tobramycin, or gentamicin. The susceptibilities of urea-positive isolates of P. stuartii resembled more closely the susceptibilities of urea-negative isolates of this species than those of P. rettgeri isolates, a finding consistent with the recent recommendation for transferring such urea-positive strains to P. stuartii. Among P. stuartii isolates, marked resistance to cefoxitin accompanied by susceptibility to cefamandole was predominantly restricted to isolates of one serotype (055). The use of isolates that had been serotyped and clafied according to recent proposals for taxonomic changes in the Proteeae provided for clearer demonstration of species differences in susceptibility.The genus Providencia, according to recent proposals for reclasification (2), includes three species, namely, P. alcalifaciens, P. stuartii, and P. rettgeri. The latter species was previously included in the genus Proteus, and some ureapositive isolates now classified as P. stuartii were usually classified also as Proteus rettgeri (11). The bacteria of the genus Providencia are gram negative and rod shaped and belong to the family Enterobacteriaceae. They have been reported to cause infections of the intestinal tract (1, 12) and the urinary tract (6, 15) and have been implicated in the establishment of nosocomial infections (3,7,12,14,16,17).Our interest in these bacteria has led us to establish serotyping schemes, and we have serotyped numerous isolates ofeach species during the course of other investigations (8)(9)(10) (4). A collection of 630 P. stuartii isolates included both urea-negative and ureapositive isolates from different hospitals as described previously (10), and the 537 P. rettgeri isolates in our collection were mostly those that were described earlier (9) and included isolates from different hospitals, public health laboratories, animals, and polluted water. All isolates were serotyped in connection with previous studies or at the request of the contributors. Currently, 46, 17, and 93 0 serotypes have been reported for P. alcalifaciens (8), P. stuartii (10), and P. rettgeri (9), respectively, and isolates of each serotype were included in the respective collections. The distribution of the isolates according to their serotypes has been published previously (8)(9)(10).Antibiotics.

Antibiogram, Biochemical Reactions and Biotyping of Biofield Treated <i>Providencia rettgeri</i>

“…Certain antimicrobials such as amikacin, ampicillin/sulbactam, aztreonam, cefazolin, cefepime, cefotetan, cefoxitin, ceftazidime, and cephalothin showed two-fold reduction in MIC values in all the treated groups as compared to the control. The control MIC values of cefoxitin (>16 µg/mL) and cephalothin (>16 µg/mL) were well matched with literature reported data [17]. In this experiment, the MIC values of cefoxitin and cephalothin were reduced by two-fold after biofield energy treatment in both lyophilized as well as revived treated groups as compared to the control.…”

Molecular analysis of clinical isolates of Providencia alcalifaciens

“…In accordance with previous observations [25,26], most of the P. alcalifaciens isolates studied were sensitive to several antimicrobial drugs. Although multiple resistance to ampicillin, co-trimoxazole, sulphamethoxazole and tetracycline was observed in some isolates, no correlation between antibiotic resistance and the presence of a particular plasmid could be demonstrated.…”

Intrinsic Resistance: A Significant Characteristic in Evaluating Antibiotic Sensitivity Pattern [Response to Letter]

“… 4 More than 60% of P. stuartii isolates were found to be sensitive to aminoglycosides (gentamicin, streptomycin, and tobramycin), penicillin (amoxicillin, Augmentin, and ampicillin). 5–7 This substantial evidence revealed that P. stuartii is not intrinsically resistant to the aforementioned antibiotics (Ampicillin, Gentamicin, and Tobramycin) at this time. (b) Further, this study reported 16.7% (1 out of 6 strains) resistance in Streptococcus pneumoniae to penicillin.…”

“…2 Moreover, intrinsic resistance is highly important as it along with another resistance mechanism may result in poor clinical outcomes. 4 , 5 …”