| Abstract|| |
Indole negative Proteus species are invariably incorrectly identified as Proteus mirabilis, often missing out isolates of Proteus penneri. We report a case of extended spectrum beta lactamase producing and multidrug-resistant P. penneri isolated from pus from pressure sore of a patient of road traffic accident. Correct and rapid isolation and identification of such resistant pathogen are important as they are significant nosocomial threat.
Keywords: Extended spectrum beta lactamase producing, multidrug-resistant, Proteus penneri
|How to cite this article:|
Pandey A, Verma H, Asthana AK, Madan M. Extended spectrum beta lactamase producing Proteus penneri: A rare missed pathogen?. Indian J Pathol Microbiol 2014;57:489-91
|How to cite this URL:|
Pandey A, Verma H, Asthana AK, Madan M. Extended spectrum beta lactamase producing Proteus penneri: A rare missed pathogen?. Indian J Pathol Microbiol [serial online] 2014 [cited 2020 May 29];57:489-91. Available from: http://www.ijpmonline.org/text.asp?2014/57/3/489/138791
| Introduction|| |
The clinical significance of Proteus penneri, described in 1982 as a new species and previously known as Proteus vulgaris indole negative, is poorly documented. ,, Like P. vulgaris, P. penneri is naturally resistant to ampicillin, narrow spectrum cephalosporins, and cefuroxime by the production of beta lactamase commonly known as cefuroximase.  Extended spectrum beta lactamase (ESBL) positive and multidrug-resistant (MDR) P. penneri was isolated from pus from pressure sore of a patient of road traffic accident. The authors want to present this case with the objectives to highlight the conventional methods employed for identification of P. penneri up to species level so as that it is not missed out in routine microbiological practice and simultaneously create awareness regarding the clinical significance of such resistant pathogen as they are significant nosocomial threat. To the best of our knowledge wound infection due to ESBL producing P. penneri has not been reported from North India.
| Case report|| |
A 28-year-old male patient with alleged history of road traffic accident underwent spinal surgery in a private hospital. Two months later, he developed a pressure sore over the lateral aspect of thigh for which he was referred to our hospital. Grafting was done over the wound area and the patient was discharged from the hospital after a period of 1 month. He was readmitted again after 20 days with pressure sores over the same area [Figure 1]. Pus sample from pressure sore was collected and sent to clinical microbiology laboratory for culture and sensitivity. Swarming growth with beta hemolysis was seen on blood agar (BA) plate [Figure 2] and pure growth of nonlactose fermenting colonies was seen on MacConkey agar plate. Presumptive identification of Proteus species was made on the basis of swarming on BA and biochemical analysis was performed, which revealed the isolate to be negative for the following reactions: Oxidase, indole (24 h, 48 h), Voges-Proskauer, Simmons citrate, hydrogen sulphide. The following reactions were positive: Catalase, methyl red, urease, phenylalanine, maltose, sucrose and fermentation of glucose without production of gas. As the isolate was negative for indole as well as hydrogen sulphide in triple sugar iron (TSI) and gas in durrhams tube, a repeat of all the three tests were performed, which again showed negative reactions. Therefore, an extended biochemical analysis was performed to identify the species, which revealed the isolate also to be negative for salicin, aesculin (24 h, 48 h), mannitol, sorbitol, trehalose, malonate, arabinose and ornithine dcarboxylation reaction (5-7 days). On the basis of cultural characteristics and the extended biochemical reactions the isolate was identified conventionally as P. penneri,, which was also reconfirmed by Vitek 2C (bioMerieux, France). Using the Clinical Laboratory Standard Institute  approved phenotypic confirmatory test P. penneri isolated was an ESBL producer with resistance to more than three antibiotics, including tetracycline, chloramphenicol, gentamicin, amikacin, ciprofloxacin, and cotrimoxazole, but was sensitive only to meropenem and imipenem. Following the sensitivity report the patient was administered an 8 hourly dose of meropenem 1g in 100 ml as an infusion in normal saline along with management of bed sore. Unfortunately, the response to treatment and the clinical outcome of the infection could not be assessed and a repeat culture from the wound site could not be attempted as the patients relatives took him against medical advice and we lost him on follow-up.
|Figure 1: Pressure sore over the lateral aspect of thigh from which Proteus penneri was isolated|
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|Figure 2: Pure growth of Proteus penneri in blood agar plates showing swarming colonies|
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| Discussion|| |
Genus Proteus includes five named species: P. vulgaris, Proteus mirabilis, P. penneri, P. myxofaciens, and P. hauseri. Of which clinical infections are predominantly caused by P. mirabilis followed by P. vulgaris and rarely by P. penneri. The latter is invariably misidentified as P. mirabilis because both are indole negative in routine biochemical testing.  Although strains of P. penneri have been reported to be isolated from urine, stool and blood their clinical significance is largely unknown.  P. penneri has the ability to cause major infectious diseases and nosocomial outbreaks.  In the present case, we isolated P. penneri as a sole pathogen from pressure sore but because the sample was open pus, to judge whether the isolate was a pathogen or just a colonizer was difficult. Similarly, Kishore 2012  has reported in all the eight cases he has described that P. penneri was isolated as a sole pathogen in pure culture and all the cases had some underlying disease. A repeat pus sample from the same site or blood for culture could not be collected as we lost the patient on follow-up. Feglo et al. 2010  in a study of 200 species of Proteus isolates had shown P. penneri to be the most common isolate from wound followed by ear swab and reported 100% of their isolates of P. penneri to be MDR that is resistance to at least three antibiotics. Moreover, the P. penneri isolated in the present case was ESBL producing and MDR. Identification, treatment and management of such pathogen and/or colonizer is of utmost importance as such resistant strains may spread into various inpatient units in the hospital and be a significant nosocomial threat. To the best of our knowledge, this is the first report of ESBL positive P. penneri being isolated from North India. Owing to lack of awareness and inability of many laboratories across the country to identify P. penneri isolates correctly, there are limited reports of P. penneri from the country. 
Kishore 2012  has reported, that biochemically the strains of P. penneri are known to be nonproducer of the enzyme ornithine decarboxylase and are uniformly salicin negative, but acidify maltose, these characters were strictly adhered to and were seen among all the isolates. However, a few variations were seen in the reactions in their study, e.g., citrate positive and H 2 S negative. The key biochemical that initially motivated us was a negative test for indole and hydrogen sulphide in TSI followed by fermentation of glucose with no gas in durrhams tube. The variability in biochemical reactions could not be compared as ours was a single clinical isolate. Though biochemical tests for species identification were performed, a16sRNA sequencing for species identification may be needed in such cases. However, due to limited resources it could not be done. Thus by biotyping whenever P. penneri is suspected, a chloramphenicol susceptibility test should be performed for identification purposes. P. penneri is chloramphenicol resistant, whereas all other indole negative Proteus spp. are chloramphenicol sensitive. 
It has been reported that P. penneri strains are naturally resistant  to penicillin G, amoxicillin, cephalosporins (i.e., cefaclor, cefazoline, cefuroxime and cefdinir), oxacillin, most of the macrolides but are naturally sensitive to aminoglycosides, carbapenems, aztreonam, quinolones, and cotrimoxazole. The major mechanism of antimicrobial drug resistance is determined chromosomally  with hyperproduction of chrosomally encoded betalactamases occasssionally due to plasmids. However, typing by antibiogram found P. penneri to be highly heterogeneous MDR strains and was of limited value. Hence, efforts should be made to identify P. penneri by ribotyping and pulse field gel electrophoresis in order to find its incidence, predisposing host factors and the clinical significance of this missed bacterium. Further, patients with underlying disease going for abdominal or urogenital surgeries should be examined carefully for P. penneri infections because of their MDR nature with potential to spread drug resistant plasmid nosocomially. 
Following the isolation of ESBL and MDR P. penneri, the infection control team of the hospital was informed. Contact isolation and barrier nursing care of the patient was carried out. Surveillance cultures taken from the unit from which the isolate was recovered were sterile and cultures from the hands of health care personnel working in that unit also did not grow Proteus spp. We could not identify any reservoir of P. penneri in our patient or from his surroundings. Thus, to pinpoint the source of P. penneri was difficult. Species identification and surveillance of antimicrobial resistance is essential in management and control of infections. However, such practices are usually absent in most of our hospitals mainly due to high costs involved. 
| Conclusion|| |
First, the microbiologists are advised to be suspicious of any Proteus isolates that are indole negative and hydrogen sulphide negative because these may possibly be isolates of P. penneri. Second, rapid and correct identification of such resistant strains are of utmost importance as they are significant nosocomial threat.
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Department of Microbiology, Subharti Medical College, Swami Vivekanand Subharti University, Meerut - 250 005, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
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