3 - Infectious Disease 2025 (updated)

Edema phase

Phase of lobar pneumonia rarely seen in histopathology

Gray hepatization

Phase of lobar pneumonia corresponding to successful containment of the infection and has gas exchange improvement

Resolution

Phase of lobar pneumonia corresponding to inflammatory response clearance

Red blood cells

Predominant cell in red hepatization phase

Neutrophils

Predominant cell in gray hepatization phase

Macrophages

Predominant cell in resolution phase

Streptococcus pneumoniae

Most common cause of community acquired pneumonia across all ages

Klebsiella pneumoniae

Causes "currant jelly" sputum

Legionella spp.

Associated with stay in hotel or cruise ship for the past 2 weeks

Staphylococcus aureus

Most common associated etiology of pneumonia after local influenza infection

>25 neutrophils/low-power field AND <10 squamous epithelial cells/low-power field

Sputum sample is adequate and points to a lower respiratory source if:

With suspected lung abscess, With suspected empyema

According to 2020 PSMID CAP guidelines, indications for atypical coverage for aspiration pneumonia

Lungs

Most commonly involved organ in tuberculosis (TB)

Cavitary pulmonary TB

Laryngeal TB

Forms of TB that are considered most infectious

Lymphadenitis

Most common form of extrapulmonary TB

Lower thoracic area

Upper lumbar

Site of skeletal TB (Pott disease)

Choroidal tubercle in the eye

Pathognomonic findings in miliary TB

Ghon focus

In PTB, peripheral parenchymal lesion (with or without pleural lesion)

Ghon complex

In PTB, Ghon focus + regional lymphadenopathy

Ranke complex

In PTB, healed (calcified) Ghon complex

Pyrazinamide

Most hepatotoxic anti-TB medication

Ethambutol

Anti-TB medication causing optic neuritis

Pyrazinamide

Anti-TB medication causing hyperuricemia

Fever

Only symptomatology that is consistent and adequate to designate UTI as pyelonephritis

Empiric antibiotic treatment

Most effective approach in the management of uncomplicated UTI

• Pregnancy

• If patient will undergo urologic interventions

Indications for the treatment of asymptomatic bacteriuria

Foodborne or waterborne transmission

Most common mode of transmission of typhoid fever

Fever and abdominal pain

Hallmark features of typhoid fever

Prolonged Fever

Most prominent symptom of typhoid fever

3rd and 4th week of Illness

GI bleeding and perforation in typhoid fever

Bone marrow

Specimen with the highest sensitivity for isolating Salmonella typhi or Salmonella paratyphi

3rd week of illness

Stool culture for typhoid fever may be positive in this week

3rd generation cephalosporin (Ceftriaxone), Azithromycin

Preferred empiric antibiotics for typhoid fever

2.5 nanograms per kilogram body weight

Minimal lethal dose of tetanospasmin

Trismus, Opisthotonos, Risus sardonicus

Triad of tetanus

Metronidazole

Antibiotic of choice for tetanus

Penicillin

This antibiotic is an alternative for tetanus management but can cause exacerbations of spasms

Rats

Most important reservoir of Leptospira

Blood

Specimen that becomes positive during the leptospiremic phase of leptospirosis

Urine

Specimen that becomes positive during the immune phase of leptospirosis

• Jaundice

• Renal dysfunction

• Bleeding manifestation (pulmonary hemorrhage)

Components of Weil triad

Hyponatremia, Hypokalemia

Typical electrolyte abnormalities in leptospirosis

Magnesium

Loss of this electrolyte in the urine is uniquely associated with leptospiral nephropathy

Nonoliguric, hypokalemia AKI

Most common type of AKI seen in leptospirosis

1:200 – 1:800 single titer

Microagglutination test result that is diagnostic of leptospirosis (based on 21st HPIM)

1:1600 single titer

Microagglutination test result that is diagnostic of leptospirosis (based on PSMID 2010 Leptospirosis CPG)

Oral Doxycycline

Primary therapy for mild leptospirosis

IV Penicillin

Primary therapy for moderate/severe leptospirosis

Schistosoma japonicum

Most prevalent etiologic agent causing schistosomiasis in the Philippines

Oncomelania hupensis quadrasi

Intermediate host of Schistosoma japonicum in the Philippines

Swimmer’s itch

Dermatitis associated with cercarial invasion of Schistosoma

Katayama fever

Acute schistosomiasis

Detection of egg

Standard diagnostic tool for schistosomiasis

Praziquantel 60 mg/kg in 3 divided doses in 1 day, as single treatment

Drug of choice for schistosomiasis

Humans

Intermediate host of Plasmodium sp.

Anopheles mosquitoes

Definitive host of Plasmodium sp.

Coma

Characteristic and ominous feature of falciparum malaria

Discrete spots of retinal opacification

Most common fundoscopic feature of falciparum malaria

<40 mg/dL

Amount of glucose that can increase risk for clinical seizures in falciparum malaria

Quinine

Antimalarial drug that increases risk for hypoglycemia

Giemsa stain

Preferred staining technique in the diagnosis of malaria

Blood thick smear

Type of smear that can only detect the presence of Plasmodium but cannot speciate it

Blood thin smear

Type of smear that can speciate Plasmodium

Artesunate

Primary drug of choice for severe falciparum malaria

Mefloquine

Only antimalarial agent available for pregnant patients (2nd or 3rd trimester) going to areas endemic with malaria

Macrophages

Reservoirs of HIV virions

Helper T cells

Primary target of HIV virions

Blood transfusion

Parenteral mode conferring highest risk of HIV transmission

Receptive anal intercourse

Sexual mode conferring highest risk of HIV transmission

HIV enzyme immunoassay

Screening tool used in HIV diagnosis

Western blot

Confirmatory tool used in HIV diagnosis

CD4 count

Best predictor of the immediate state of immunologic competence of the HIV patient

HIV viral load

Best predictor of the long-term clinical outcome among HIV patients; used in the assessment of effectiveness of antiretroviral therapy

Pneumocystis jirovecii

Most common cause of pneumonia in HIV patients

Trimethoprim-Sulfamethoxazole

Regimen for the prophylaxis of Pneumocystis and Toxoplasma infection among HIV patients

Macrolides

Regimen for the prophylaxis of Mycobacterium avium complex (MAC) infection among HIV patients

RT-PCR of the nasopharynx

Gold standard in the diagnosis of COVID19