Morganella morganii
Revisión del 01:02 28 ene 2026 de Ostermayer (discusión | contribs.) (Created page with "==Background== *Gram-negative, facultative anaerobic rod *Member of the tribe Proteeae (along with ''Proteus'' and ''Providencia'') *Important cause of nosocomial infections, particularly CAUTIs *Typically affects immunocompromised, elderly, or nursing home residents *Possesses chromosomal AmpC $\beta$-lactamase (inducible resistance) ==Clinical Features== *Urinary Tract Infection **Most common presentation **Often ass...")
Background
- Gram-negative, facultative anaerobic rod
- Member of the tribe Proteeae (along with Proteus and Providencia)
- Important cause of nosocomial infections, particularly CAUTIs
- Typically affects immunocompromised, elderly, or nursing home residents
- Possesses chromosomal AmpC $\beta$-lactamase (inducible resistance)
Clinical Features
- Urinary Tract Infection
- Most common presentation
- Often associated with long-term indwelling urinary catheters
- Urease-producing organism (leads to alkaline urine and Struvite stone/Staghorn calculi formation)
- Purple urine bag syndrome (rare, but classic association)
- Skin and Soft Tissue Infection
- Surgical site infections
- Snake bites (Common isolate in oral flora of snakes, infections secondary to cobra/viper bites)
- Sepsis/Bacteremia
- High mortality rate with inadequate initial antibiotic coverage due to resistance profile
- Meningitis
- Rare, typically nosocomial or secondary to brain abscess/otogenic infection
- Chorioamnionitis (Rare)
Differential Diagnosis
Dysuria
- Genitourinary infection
- Acute cystitis ("UTI")
- Pyelonephritis
- Urethritis
- Chronic cystitis
- Infected nephrolithiasis
- Prostatitis
- Epididymitis
- Renal abscess/perinephric abscess
- Emphysematous pyelonephritis
- Nephrolithiasis
- Urethral issue
- Urethritis
- Urolithiasis
- Urethral foreign body
- Urethral diverticulum
- Allergic reaction (contact dermatitis)
- Chemical irritation
- Urethral stricture or obstruction
- Trauma to vagina, urethra, or bladder
- Gynecologic
- Vaginitis/cervicitis
- PID
- Genital herpes
- Pelvic organ prolapse
- Fistula
- Cystocele
- Other
- Diverticulitis
- Interstitial cystitis
- Behavioral symptom without detectable pathology
Evaluation
- Urinalysis: Alkaline pH (often > 7.5 due to urease)
- CBC: Leukocytosis
- Lactate: Elevated in sepsis
- Blood Cx: Mandatory if febrile or hypothermic
- Imaging:
- CT KUB if concern for struvite stones/obstruction
- CT Soft Tissue if concern for necrotizing fasciitis (snake bite/wound)
Management
- Source control
- Remove/replace indwelling urinary catheter
- Debridement of infected wounds/bites
- Antibiotic considerations relating to AmpC $\beta$-lactamase
- Intrinsic resistance to many $\beta$-lactams
- Avoid first/second generation cephalosporins and ampicillin
- Inducible resistance may occur with 3rd generation cephalosporins (Ceftriaxone)
- Preferred agents: Carbapenems, Cefepime, Fluoroquinolones, or Aminoglycosides
Antibiotic Sensitivities[1]
| Category | Antibiotic | Sensitivity |
| Penicillins | Penicillin G | R |
| Penicillin V | R | |
| Anti-Staphylocccal Penicillins | Methicillin | R |
| Nafcillin/Oxacillin | R | |
| Amino-Penicillins | AMP/Amox | R |
| Amox-Clav | R | |
| AMP-Sulb | R | |
| Anti-Pseudomonal Penicillins | Ticarcillin | S |
| Pip-Tazo | S | |
| Piperacillin | S | |
| Carbapenems | Doripenem | S |
| Ertapenem | S | |
| Imipenem | S | |
| Meropenem | S | |
| Aztreonam | S | |
| Fluoroquinolones | Ciprofloxacin | S |
| Levofloxacin | S | |
| Moxifloxacin | S | |
| 1st G Cephalo | Cefazolin | R |
| Cephalexin | R | |
| 2nd G. Cephalo | Cefotetan | R |
| Cefoxitin | R | |
| Cefuroxime | R | |
| 3rd G. Cephalo | Cefotaxime | X1 |
| CefTRIAXone | X1 | |
| CefTAZidime | S | |
| Cefdinir | X1 | |
| 4th G. Cephalo | Cefepime | S |
| Aminoglycosides | Gentamicin | S |
| Tobramycin | S | |
| Amikacin | S | |
| Clindamycin | R | |
| Macrolides | Erythromycin | R |
| Azithromycin | R | |
| Tetracyclines | Doxycycline | X1 |
| Tigecycline | R | |
| Glyco/Lipoglycopeptides | Vancomycin | R |
| Daptomycin | R | |
| Urinary Agents | Nitrofurantoin | R |
| Fosfomycin | R | |
| Other | Trimethoprim | R |
| TMP-SMX | S | |
| Metronidazole | R | |
| Linezolid | R | |
| Colistimethate | R | |
| Polymyxin B | R |
Key
- S susceptible/sensitive (usually)
- I intermediate (variably susceptible/resistant)
- R resistant (or not effective clinically)
- S+ synergistic with cell wall antibiotics
- U sensitive for UTI only (non systemic infection)
- X1 no data
- X2 active in vitro, but not used clinically
- X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
- X4 active in vitro, but not clinically effective for strep pneumonia
- Note: Morganella has intrinsic resistance to Oxacillin, Ampicillin, Amoxicillin, most 1st/2nd Gen Cephalosporins, Macrolides, Lincosamides, Glycopeptides, Nitrofurantoin, and Polymyxins (Colistin).
Table Overview
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References
- ↑ Sanford Guide to Antimicrobial Therapy