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Year : 2002  |  Volume : 18  |  Issue : 2  |  Page : 123-128

Complicated nosocomial UTI caused by nonfermenters

Departments of Medical Microbiology and Urology, Postgraduate Institute of Medical Education & Research, Chandigarh, India

Correspondence Address:
Meera Sharma
Department of Medical Microbiology, PGIMER, Chandigarh- 160 012
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Source of Support: None, Conflict of Interest: None

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Aerobic nonfermenting gram-negative bacilli (nonfer­menters) usually considered as contaminants are emerg­ing as important nosocomial pathogens. 110 such strains obtained from 4200 consecutive urinary tract specimens were characterized by a battery of biochemical tests. Antibiotic susceptibility was tested against gentamicin, amikacin, netilmicin, ceftazidime, piperacillin and ciprof oxacin. Significance was assigned by taking into account clinical details and isolation of the same organ­ism in the repeat specimen. Pseudomonas spp. (45.5%) were the commonest followed by Acinetobacter spp. (39%), Alcaligenes spp. (8%) and Flavobacter spp. (3.63%). Two strains of Weeksella virosa, and one each of Xanthomonas rnaltophilia and CDCllg were also re­covered. Pseudomonas aeruginosa and Acinetobacter baumanii were the most common significant isolates (62.9% and 25.9% respectively). Alcaligenes spp. was found to be etiologically significant in 5 out of 7 cases. In only 2 cases (4%) isolation of a Pseudomonas spp other than Paeruginosa was considered significant. Out of 4 strains of Flavobacter spp. only one could be confirmed as significant. Postoperative period (42.6%) followed by obstructive uropathy (32%) and surgery on urinary tract (8%) were commonest risk factors. All strains except a few showed high level of drug resistance.

Keywords: Urinary Tract Infection; Nosocomial; Nonfermenters

How to cite this article:
Meharwal S K, Taneja N, Sharma S K, Sharma M. Complicated nosocomial UTI caused by nonfermenters. Indian J Urol 2002;18:123-8

How to cite this URL:
Meharwal S K, Taneja N, Sharma S K, Sharma M. Complicated nosocomial UTI caused by nonfermenters. Indian J Urol [serial online] 2002 [cited 2023 Mar 24];18:123-8. Available from:

   Introduction Top

Urinary tract infections are the second most common bacterial infections affecting humans throughout their lifetime. They are frequent cause of morbidity in outpa­tients as well as most frequent cause of nosocomial in­fection in many hospitals. [1] E.coli is the commonest urinary pathogen accounting for over 80% of commu­nity-acquired infection. Far less commonly Klebsiella spp, Proteus spp and Staphylococcus saprophyticus Scientific Name Search  are responsible for community-acquired infection. The distri­bution of urinary pathogens in hospitalized patients is dif­ferent, with E.coli accounting for about 50% of infections. Enterococcus, Klebsiella, Enterobacter, Citrobacter, Serra­tia, Pseudomonas aeruginosa, Providencia, and Staphylo­coccus epidermidis account for most of the rest. [2]

Aerobic nonfermenting gram-negative bacilli (nonfer­menters) are a heterogeneous group of organisms that are either incapable of utilizing carbohydrates as a source of energy or degrade them via oxidative rather than fermentative pathway. [3] This group includes organisms from diverse gen­era like Pseudomonas, Acinetobacter, Alcaligenes, Flavo­bacter, Oligella, Flavimonas, Agrobacter Weeksiella, etc. A few of these have not been named and are designated by CDC numbers like CDC11g. These organisms are common inhabitants of soil and water. They also exist as harmless parasites on the mucus membranes of humans and animals. Though primarily regarded as contaminants or incidental organisms, they are becoming increasingly important as opportunistic pathogens in immunocompromised patients. They can also cause infection by gaining access to normally sterile body sites through trauma. [4] Though these organisms vary in their potential to cause infection and antibiotic sus­ceptibility, there are common disease manifestations and risk factors. These organisms have been implicated in causing septicemia, meningitis, osteomyelitis, wound infections, pneumonias and urinary tract infections. Risk factors include immunosuppression, trauma, foreign body, broad-spectrum antibiotic use and infused body fluids like saline irrigations. [5]  Pseudomonas aeruginosa Scientific Name Search i>is the predominant and most well known organism out of this heterogeneous group. This is partly due to its easy recognition in the laboratory as it produces pyocyanin, a blue-green pigment. Other organisms usually get ignored as contaminants because identification up to species level is cumbersome and laborious and not possible in a busy routine microbiology laboratory. Evaluation of significance of isolating these organisms is com­plicated by the fact that they are usually present in mixed culture and the clinicians are rather unfamiliar with their names. The present study was taken up to characterize these organisms from urinary tract specimens and evalu­ate their role as pathogens.

   Materials and Methods Top

Four thousand and eight hundred urinary tract (UT) specimens were consecutively screened for the presence of nonfermenters over a three-month period from January 2000 to March 2000. Only those strains which were re­covered in pure culture and significant numbers (>10 5 cfu/ ml) were included. 110 such nonfermenters were charac­terized by using a battery of tests which included gram stain, oxidase reaction, catalase test, motility, pigment pro­duction, gelatin liquefaction, growth on MacConkey's me­dium, hemolysis on blood agar, Hugh Leifson's O-F test with 1% glucose, lactose and xylose each, lysine and or­nithine decarboxylase test, arginine dehydrolase test, ure­ase production, citrate utilization, aesculin hydrolysis, growth at 4°C and 42°C, gelatin liquefaction, nitrate re­duction and denitrification and H 2 S production in TSI. For seven strains, which were non-motile, oxidase and cata­lase positive and produced yellow coloured colonies (pro­visional Flavobacter group), further biochemicals were put to speciate them. These included Hugh Leifson's O-F with maltose (1%), sucrose (1%) and mannitol (1%), penicillin susceptibility (IOU) and polymyxin (300U) susceptibil­ity. The criteria laid down by CDC Atlanta' were used to identify these organisms. The strains were tested for in­vitro susceptibility to gentamicin (10 ug), amikacin (100 ug), netilmicin (30 ug), ceftazidime (30 ug), piperacillin (100 ug) and ciprofloxacin (5 ug) by modified Stoke's method. [8] All media and antibiotic discs were from Hi­media. A repeat sample was obtained in admitted patients. Following information was recorded for each patient: age, ward case, symptoms and risk factors for development of UTI. The strains were considered to be confirmed signifi­cance if patient was symptomatic with/without presence of pyuria and repeat specimen was positive for the same organism. The significance was assigned as probable but not confirmed if in such cases a repeat sample was nega­tive or could not be obtained. The strains were considered as contaminant if patients were asymptomatic, there was no pyuria, the repeat samples negative and no risk factors for development of complicated UTI were present.

   Results Top

110 strains of nonfermenters were obtained from 86 pa­tients. 65 patients were hospitalized and 21 were attend­ing the Outpatients Department at PGIMER, Chandigarh. 45 patients were males and 41 were females. Maximum number of patients belonged to the age groups 16-45 years [Table - 1]. Risk factors for development for complicated UTI were presented in 87.2% of cases. Postoperative pe­riod (42.6%) followed by obstructive uropathy (32%) and surgery on urinary tract (8%) were the commonest risk factors [Table - 2]. Pseudomonas spp. were the commonest (45.4%) followed by Acinetobacter spp. (39.0%), Alcali­genes spp. (8.1%) and Flavobacter spp. (3.63%). One strain (0.9%) of Weeksella virosa, Xanthomonas malto­philia and CDCllg were recovered [Table - 4]. Maximum resistance was observed for strains of Acinetobacter bau­manii. However, all the strains of nonfermenting bacilli except PP fluorescence showed very high level of resis­tance as depicted in [Table - 3]. Piperacillin (41.8% resist­ance) and amikacin (47.2% resistance) were the most effective in vitro antibiotics. In 39.5% of cases strains could be confirmed as etiological significant. For 47.6% of cases significance was probable and only 12% of the strains were contaminants. P.aeruginosa was the most significant spe­cies (17 patients-62.9%). In only 29.6% (7 patients), Acinetobacter spp. could be confirmed as significant. Vari­ous Alcaligenes spp. were significant in 55.5% of cases (5 patients). Only in 2 cases (4%) isolation of Pseudomonas spp. other than Pseudomonas aeruginosa was considered significant. Out of 4 strains of Flavobacter spp. only one could be confirmed as significant. The two strains of  Weeksella virosa Scientific Name Search were recovered from same patients and were considered significant [Table - 4].

   Discussion Top

Urinary tract infections are found in all age groups. One percent of all neonates have bacteria in bladder urine. [9] The incidence is higher in male infants due to presence of con­genital anomalies. [10] From adulthood to the age group of 65 years, the incidence of UTI is very high in women as com­pared to men. In older patients there is a progressive decrease in the female to male ratio due to development of obstructive uropathy from the prostatic enlargement. In the present study out of 7 male infants 5 had posterior urethral valves with hydronephrosis. In the sexually active age group (16-45 years) males and females were equally affected. This was due to the fact that most of the infections in this par­ticular study were complicated; risk factors being present in 87.2% of patients. Postoperative period (42.6%), fol­lowed by obstructive uropathy (32%) and surgery on uri­nary tract (8%) were the commonest risk factors. The high incidence in postoperative period was most probably re­lated to catheterization. Most of the patients were females (24 out of 37) undergoing caesarian section and gyneco­logical surgeries. Many of these infections were due to Acinetobacter spp, and patients improved after removal of catheter. This suggests that Acinetobacter spp. cause a colonization of urinary bladder as also observed in a pre­vious study. [11] In all the admitted patients infections were of nosocomial origin. Only 25% patients were from out­patient department (OPD) and most of these were attend­ing urology OPD because of problems like stricture urethra, vesicoureteral reflux and chronic renal failure. Though nosocomial origin of these infections cannot be proved, it was highly likely.

Pseudomonas aeruginosa is an established pathogen of urinary tract. [12] It was the commonest isolate in the present study being etiologically significant in 62.9% of cases. Pseudomonas spp. like P. fluorescence and P. putida have been recovered from urine samples [13],[14],[15],[16] but significance has been confirmed for only a few of these. In the present study none of the strains of P. putida, P pickettii and P vesicularis could be confirmed as significant. One strain of P putrifaciens was repeatedly isolated from two male infants who had bilateral vesicoureteral reflux. Signifi­cance of X.maltophilia was questionable.

Acinetobacters are ubiquitous in environment and in hospitals. [17] They account for I to 3 percent of nosocomial infections, being second only to Paeruginosa in their re­covery from clinical specimens. [5] Acinetobacters have been implicated in causation of a variety of illness including UTI. [16] Most of the infections are caused by A.baumanii. A.lwoffi is less virulent and its isolation most often indi­cates contamination rather than infection. In the study by Pederson et al [16] only 2 out of 24 strains of Acinetobacters appeared to be significant. In the current study 43 strains of Acinetobacter spp. were obtained. A.baumanni (31) were the commonest followed by A.lwoffi (7) and A.calcoaceticus (3). One strain each of A.hemolyticus and A. junii were recovered. Only 7 strains of A.baumanii and one strain of A.calcoaceticus could be confirmed as sig­nificant.

Alcaligenes fecalis has also been associated with cau­sation of serious infections like pyelonephritis and has been isolated from asymptomatic renal calculi. [6] Contamination of irrigating fluids used in the genitourinary procedures has resulted in common source epidemics of UTI due to this organism. [17] In the present study, 9 strains were ob­tained. Only 5 of these could be etiologically confirmed as urinary tract pathogens. These include  Alcaligenes xylosoxidans Scientific Name Search sub spp. xylosoxidans [2], A. fecalis (2) and A.xylosoxidans sub spp. piechaudii (1).

Reports in literature [16],[18] indicate that saccharolytic Flavobacteria are frequently recovered from clinical speci­mens. In the present study 2 each of F.indologenes, Fodoratum, Weeksella virosa and one of CDClIg were obtained. The strains of W.virosa belonged to the same patient and were repeatedly isolated from a patient who underwent surgery on urinary tract for nephrolithiasis. The strain was multidrug resistant in contrast to reports in literature. [19],[20] One of the Eindologenes was considered significant. This patient had stricture urethra. The two strains of Fodoratum were from males who had undergone sur­gery on gastrointestinal tract. None of these could be con­firmed as significant as repeat samples were negative. A very high level of drug resistance was observed in general for all strains. This could be due to the fact that most of these infections were of nosocomial origin. Some patients especially those who had surgery on urinary tract, devel­oped persistent infection and were treated with multiple antibiotics. Piperacillin and amikacin appeared to be the most effective antibiotics in vitro. From the present study it can be concluded that nonfermenters though regarded as contaminants are important agents causing complicated nosocomial infections. If recovered in pure culture, a re­peat specimen should be taken to confirm their presence, and the strain should be identified up to the species level.

   References Top

1.Sussman M. Urinary tract infections. In : Topley and Wilson's Micro­biology and Microbial infections. Hausler Jr, Sussman M eds. 9 th edn. Arnold 1998: 601-621.  Back to cited text no. 1    
2.Bryan CS. Reynolds KL. Community acquired bacteremic urinary tract infections: Epidemiology and outcome. J Urol 1984: 132: 490.  Back to cited text no. 2    
3.Koneman EW. Allen SD, Rowell Jr VR et al. In : Color atlas and textbook of diagnostic microbiology. 3' edn. Lippincott. Philadel­phia. 1988: 157-208, 493-534.  Back to cited text no. 3    
4.Nonfermentative gram-negative bacilli and coccobacilli. In : Bai­ley and Scott's Diagnostic microbiology. Baron EJ, Fine-old SM. eds. 8 th edn. Mosby 1990: 386-407.  Back to cited text no. 4    
5.Hall GS. Nonfermentative gram-negative bacilli and miscellane­ous gram negative rods. In : Textbook of diagnostic Microbiology. Conneie R Mahan. George Manuselis Jr. eds. Philadelphia 1995: 513-538.  Back to cited text no. 5    
6.Gardener P. Griffin W B, Morton NS. Lawrence JK. Nonfermentative gram-negative bacilli of nosocomial interest. Am J Med 1970: 48: 735-774.  Back to cited text no. 6    
7.Weyant SR, Moss CW, Weaver ER, Hollis GD et al. Identification of unusual pathogenic gram-negative aerobic and facultative anaero­bic bacteria. 2i' edn 1996. Williams and Wilkins. Baltimore.  Back to cited text no. 7    
8.Aggarwal KC. Antibiotic sensitivity test by disc diffusion method. IJPM 1994: 17: 149-159.  Back to cited text no. 8    
9.Wettergen B. Jodal U, Jonasson G. Epidemiology of bacteriuria during first year of life. Acta Paediatr Scandinavica 1985; 74: 925­-933.  Back to cited text no. 9    
10.Stansfeld JM. Clinical observation relating to incidence and etiology of urinary tract infections in children. Br Med J 1966: 1: 631-635.  Back to cited text no. 10    
11.Bal A, Bhalla P. Prevalence and clinical significance of nonfermen­tative bacteria in urinary tract infection in a Delhi Hospital. IJMR 1988; 87: 537-578.  Back to cited text no. 11    
12.Rambaugh KP, Griswold JA. Hamood AN. Pseudomonas aeruginosa: Strains obtained from patients with tracheal, urinary tract and wound infection; variation in virulence factors and viru­lence genes. J Hosp Infect 1999: 43: 211-215.  Back to cited text no. 12    
13.Gilardi LG. Infrequently encountered Pseudomonas spp. causing infection in humans. Ann Int Med 1972; 77: 211-215.  Back to cited text no. 13    
14.Veenu, Sikka R. Arora DR. Isolation and susceptibility pattern of nonfermentative gram-negative bacilli from clinical samples. IJMM 1998: 17: 14-18.  Back to cited text no. 14    
15.Yashodhara P. Shyamala S. Identification and characterization of nonfermenters from clinical specimens. IJMM 1997; 15: 195-197.  Back to cited text no. 15    
16.Pederson MB. Marso E, Pickett MJ. Nonfermentative bacilli asso­ciated with man; III. Pathogenicity and antibiotic susceptibility. Am J Clin Path 1970: 54: 178-192.  Back to cited text no. 16    
17.Quinn PJ. Clinical problems posed by multidrug resistant nonfer­menting gram-pathogens. CID 1998: 27(suppl): sl 17-124.  Back to cited text no. 17    
18.Igra S. Schwartz D. Soferman G, Konforti N. Flavobacterium group IIb bacteremia : report of a case and review of flavobacterium in­fections. Med Microbiol Immunol 1987; 176: 103-111.  Back to cited text no. 18    
19.Holmes B et al. Weeksella virosa spp (formerly group Ilf) found in human clinical specimens. Syst App] Microbiol 1986: 8: 185-190.  Back to cited text no. 19    
20.Reina J, Gil J Salva. Microbiological characteristics of Weeksella virosa (formerly group 11f) isolated from human genitourinary tract. J Clin Microbiol 1990; 28: 2357-2359.  Back to cited text no. 20    


  [Table - 1], [Table - 2], [Table - 3], [Table - 4]

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